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Sample records for 26al 36cl 41ca

  1. Erosion rate study at the Allchar deposit (Macedonia) based on radioactive and stable cosmogenic nuclides (26 Al, 36 Cl, 3 He, and 21 Ne)

    PubMed Central

    Cvetković, V.; Niedermann, S.; Pejović, V.; Amthauer, G.; Boev, B.; Bosch, F.; Aničin, I.; Henning, W. F.

    2016-01-01

    Abstract This paper focuses on constraining the erosion rate in the area of the Allchar Sb‐As‐Tl‐Au deposit (Macedonia). It contains the largest known reserves of lorandite (TlAsS2), which is essential for the LORanditeEXperiment (LOREX), aimed at determining the long‐term solar neutrino flux. Because the erosion history of the Allchar area is crucial for the success of LOREX, we applied terrestrial in situ cosmogenic nuclides including both radioactive (26Al and 36Cl) and stable (3He and 21Ne) nuclides in quartz, dolomite/calcite, sanidine, and diopside. The obtained results suggest that there is accordance in the values obtained by applying 26Al, 36Cl, and 21Ne for around 85% of the entire sample collection, with resulting erosion rates varying from several tens of m/Ma to ∼165 m/Ma. The samples from four locations (L‐8 CD, L1b/R, L1c/R, and L‐4/ADR) give erosion rates between 300 and 400 m/Ma. Although these localities reveal remarkably higher values, which may be explained by burial events that occurred in part of Allchar, the erosion rate estimates mostly in the range between 50 and 100 m/Ma. This range further enables us to estimate the vertical erosion rate values for the two main ore bodies Crven Dol and Centralni Deo. We also estimate that the lower and upper limits of average paleo‐depths for the ore body Centralni Deo from 4.3 Ma to the present are 250–290 and 750–790 m, respectively, whereas the upper limit of paleo‐depth for the ore body Crven Dol over the same geological age is 860 m. The estimated paleo‐depth values allow estimating the relative contributions of 205Pb derived from pp‐neutrino and fast cosmic‐ray muons, respectively, which is an important prerequisite for the LOREX experiment. PMID:27587984

  2. Depth-dependent Concentrations of Cosmogenic 10Be, 26Al, 36Cl, HEc, NEc, and ARc in the Old Woman Iron Meteorite

    NASA Astrophysics Data System (ADS)

    Lavielle, B.; Nishiizumi, K.; Marti, K.; Jeannot, J.-P.; Caffee, M. W.; Finkel, R. C.

    1995-09-01

    We report measurements of 1OBe7 26AI, 36CI, and of light noble gases in 6 samples of the type IIB Old Woman iron meteorite. The aim of this work is to study the depth dependence of the production rates of cosmogenic nuclides in iron meteorites. Old Woman is a large single mass of 2753 kg. Five samples have been taken from a slice of about 100 cm x 50 cm. One other sample was located roughly 40 cm above the center of the slice in a perpendicular direction. The distances between any two samples vary from 36.5 cm to 57.5 cm. Studies of cosmogenic nuclides in samples of known locations are very useful for the validation of models describing the production of cosmogenic nuclides in meteorites. Cosmogenic radionuclides were measured by accelerator mass spectrometry at Lawrence Livermore National Laboratory. Partial results have been reported earlier [1]. Concentrations of 4He, 21Ne and 38Ar in aliquots of the samples were determined by conventional mass spectrometry using an isotopic dilution method. The ratio 3He/4He appears to be almost constant with a value of 0.12 - ().13. This is about half the value generally observed in iron meteorites. Similar low ratios have been previously observed in some irons and in chondritic metal and reflect diffusion losses of 3H 12,31. The ratios 4He/38Ar, 4He/21Ne and 36Ar/38Ar are similar to those observed in iron meteorites indicating no significant losses of 4He. The measured ratio S = 4He/21Ne which represents one of the best indicators of shielding depth in iron meteorites, varies from 310 to 375 in samples from the slice. By using this as a shielding parameter, profiles were obtained for the different nuclides investigated in this work. Systematic decreases from the surface to the center of the meteorite are observed and the center of the meteoroid can be determined. As expected from nuclear systematics, the ratio 36Cl/36Ar is almost constant. The ratio 36Cl/10Be is relatively constant with a mean value of 4.7 indicating that the

  3. The 41Ca bomb pulse and atmospheric transport of radionuclides

    NASA Astrophysics Data System (ADS)

    Zerle, L.; Faestermann, T.; Knie, K.; Korschinek, G.; Nolte, E.; Beer, J.; Schotterer, U.

    1997-08-01

    For the first time, the 41Ca signal from the nuclear weapon tests has been measured. Calcium 41 concentrations have been determined in alpine ice of the Fiescherhorn glacier (Switzerland) with accelerator mass spectrometry. The peak concentrations have been observed to be about 3×106 atoms of 41Ca per kilogram of ice in. the 1950s. It has been found that 41Ca is produced essentially by the atoll bombs. A universal box model, able to describe atmospheric transport of radionuclides that are in gaseous form or attached to aerosols, has been developed. The model has been applied to calculate the bomb pulses of 14C, 36Cl, 41Ca, 90Sr, and 137Cs, For the transport of radionuclides that are attached to aerosols such as 41Ca, 90Sr, and 137Cs, sedimentation (gravitational settling) in the upper stratosphere has been taken into account. It has been found that the deposition of bomb-produced 36Cl on the Earth's surface is delayed compared to that of 90Sr by about 1 year because 36Cl stays gaseous in the stratosphere. The model can also be used to calculate the deposition of cosmogenic radionuclides, e.g., 36Cl and 10Be, in their natural archives, such as polar ice sheets.

  4. The Cosmic-Ray Radioactive Nuclide 36Cl and Its Propagation in the Galaxy

    NASA Astrophysics Data System (ADS)

    Connell, J. J.; DuVernois, M. A.; Simpson, J. A.

    1998-12-01

    Radioactive 36Cl has been resolved from 35Cl and 37Cl for the first time in the cosmic radiation with measurements obtained from the high-resolution High-Energy Telescope (HET) carried on the NASA-ESA Ulysses spacecraft. Within the framework of a homogeneous propagation model wherein all 36Cl is of spallation origin, the average density of the interstellar gas ρ, through which all cosmic-ray nuclei propagate, was determined. Heliospheric modulation was included in the analysis. The abundance ratio 36Cl/Cl=5.2+/-1.8% at an average energy of 238 MeV u-1 yields ρ=0.28+0.12-0.10 atoms cm-3. Although 36Cl has a relatively short half-life (τ1/2=3.01×105 yr) compared with the approximately 20 Myr confinement or escape time Tesc for cosmic rays in the Galaxy derived from 10Be or 26Al analysis, it is shown that the confinement time based on 36Cl analysis is 18+10-6 Myr. Radioactive 10Be, 26Al, and 36Cl are all produced by nuclear interactions during propagation from Galactic sources to the observer. However, 10Be, 26Al, and 36Cl are each predominantly products of different primary cosmic-ray nuclei. 54Mn is the fourth radioactive isotope measured by the Ulysses HET. Unfortunately, its decay half-life to 54Fe is difficult to determine. Recent measurements yielded τ1/2=6.3×105 yr, leading to ρ=0.40+0.23-0.15 atoms cm-3 with a confinement time Tesc=11 Myr.

  5. The French accelerator mass spectrometry facility ASTER after 4 years: Status and recent developments on 36Cl and 129I

    NASA Astrophysics Data System (ADS)

    Arnold, Maurice; Aumaître, Georges; Bourlès, Didier L.; Keddadouche, Karim; Braucher, Régis; Finkel, Robert C.; Nottoli, Emmanuelle; Benedetti, Lucilla; Merchel, Silke

    2013-01-01

    Since the acceptance tests of the French 5 MV accelerator mass spectrometry facility ASTER in 2007, routine measurement conditions for the long-lived radionuclides 10Be and 26Al have been established. Yearly sample throughput as high as over 3300 unknowns has been reached for 10Be in 2010. Cross-contamination for volatile elements has been largely solved by an ion source upgrade allowing 36Cl measurements at ASTER. However, recent long-term tests using 35Cl/37Cl samples with strongly varying ratios have shown that identical targets lead to different 35Cl/37Cl results at the 2-4% level when being measured after a time gap of 24 h while the source is running other samples. Besides time dependent mass fractionation, another likely reason for this effect might be source memory, thus, asking for sophisticated measurement strategies and improved data evaluation and eventually further ion source improvement. Finally, after establishing quality assurance by cross-calibration of secondary in-house 26Al and 41Ca standards and taking part in round-robin exercises of 10Be and 36Cl, a two-step cross-calibration of secondary in-house 129I standards has been performed. The NIST 3231 standard containing 129I/127I at (0.981 ± 0.012) × 10-6 has been used for step-wise dilution with NaI to produce gram-quantities of lower-level standards for every-day use. The resulting material SM-I-9 (129I/127I: ∼1 × 10-9) has been measured vs. AgI produced using minimum chemistry from the two NIST ampoules containing a solution with a nominal ratio 129I/127I of (0.982 ± 0.012) × 10-8. In a second stage, SM-I-10 and SM-I-11 with ratios of ∼1 × 10-10 and ∼1 × 10-11, respectively, have been cross-calibrated against SM-I-9. Individual uncertainties of the traceable secondary standards are 1.3-1.4% (2σ), mainly originating from the given uncertainty of the primary NIST 3231 at the 10-8 level. The cross-contamination for iodine is in the range of 0.4-0.6% within the first 20 h of running

  6. Formation of the Short-lived Radionuclide 36Cl in the Protoplanetary Disk During Late-stage Irradiation of a Volatile-rich Reservoir

    NASA Astrophysics Data System (ADS)

    Jacobsen, Benjamin; Matzel, Jennifer; Hutcheon, Ian D.; Krot, Alexander N.; Yin, Qing-Zhu; Nagashima, Kazuhide; Ramon, Erick C.; Weber, Peter K.; Ishii, Hope A.; Ciesla, Fred J.

    2011-04-01

    Short-lived radionuclides (SLRs) in the early solar system provide fundamental insight into protoplanetary disk evolution. We measured the 36Cl-36S-isotope abundance in wadalite (<15 μm), a secondary chlorine-bearing mineral found in calcium-aluminum-rich inclusions (CAIs) in the Allende CV chondrite, to decipher the origin of the SLR 36Cl (τ 1/2 ~ 3 × 105 yr) in the early solar system. Its presence, initial abundance, and the noticeable decoupling from 26Al raise serious questions about the origin of SLRs. The inferred initial 36Cl abundance for wadalite, corresponding to a 36Cl/35Cl ratio of (1.81 ± 0.13) × 10-5, is the highest 36Cl abundance ever reported in any early solar system material. The high level of 36Cl in wadalite and the absence of 26Al (26Al/27Al <= 3.9 × 10-6) in co-existing grossular (1) unequivocally support the production of 36Cl by late-stage solar energetic particle irradiation in the protoplanetary disk and (2) indicates that the production of 36Cl, recorded by wadalite, is unrelated to the origin of 26Al and other SLRs (10Be, 53Mn) recorded by primary minerals of CAIs and chondrules. We infer that 36Cl was largely produced by irradiation of a volatile-rich reservoir in an optically thin protoplanetary disk adjacent to the region in which the CV chondrite parent asteroid accreted while the Sun was a weak T Tauri star. Subsequently, 36Cl accreted into the Allende CV chondrite together with condensed water ices.

  7. FORMATION OF THE SHORT-LIVED RADIONUCLIDE {sup 36}Cl IN THE PROTOPLANETARY DISK DURING LATE-STAGE IRRADIATION OF A VOLATILE-RICH RESERVOIR

    SciTech Connect

    Jacobsen, Benjamin; Yin Qingzhu; Matzel, Jennifer; Hutcheon, Ian D.; Ramon, Erick C.; Weber, Peter K.; Krot, Alexander N.; Nagashima, Kazuhide; Ishii, Hope A.; Ciesla, Fred J.

    2011-04-20

    Short-lived radionuclides (SLRs) in the early solar system provide fundamental insight into protoplanetary disk evolution. We measured the {sup 36}Cl-{sup 36}S-isotope abundance in wadalite (<15 {mu}m), a secondary chlorine-bearing mineral found in calcium-aluminum-rich inclusions (CAIs) in the Allende CV chondrite, to decipher the origin of the SLR {sup 36}Cl ({tau}{sub 1/2} {approx} 3 x 10{sup 5} yr) in the early solar system. Its presence, initial abundance, and the noticeable decoupling from {sup 26}Al raise serious questions about the origin of SLRs. The inferred initial {sup 36}Cl abundance for wadalite, corresponding to a {sup 36}Cl/{sup 35}Cl ratio of (1.81 {+-} 0.13) x 10{sup -5}, is the highest {sup 36}Cl abundance ever reported in any early solar system material. The high level of {sup 36}Cl in wadalite and the absence of {sup 26}Al ({sup 26}Al/{sup 27}Al {<=} 3.9 x 10{sup -6}) in co-existing grossular (1) unequivocally support the production of {sup 36}Cl by late-stage solar energetic particle irradiation in the protoplanetary disk and (2) indicates that the production of {sup 36}Cl, recorded by wadalite, is unrelated to the origin of {sup 26}Al and other SLRs ({sup 10}Be, {sup 53}Mn) recorded by primary minerals of CAIs and chondrules. We infer that {sup 36}Cl was largely produced by irradiation of a volatile-rich reservoir in an optically thin protoplanetary disk adjacent to the region in which the CV chondrite parent asteroid accreted while the Sun was a weak T Tauri star. Subsequently, {sup 36}Cl accreted into the Allende CV chondrite together with condensed water ices.

  8. Aluminum 26, {sup 10}Be, and {sup 36}Cl depth profiles in the Canyon Diablo iron meteorite

    SciTech Connect

    Michlovich, E.S.; Elmore, D.; Vogt, S.; Lipschutz, M.E.; Masarik, J.; Reedy, R.C.

    1994-11-25

    The authors have measured activities of the long-lived cosmogenic radionuclides {sup 26}Al, {sup 10}Be, and {sup 36}Cl in 12 fragments of the iron meteorite Canyon Diablo and have constructed production rate-versus-depth profiles of those radionuclides. Profiles determined using differential particle fluxes calculated with the LAHET code system are in good agreement with {sup 26}Al, {sup 10}Be, and {sup 36}Cl experimental data, but the agreement for {sup 36}Cl was obtained only after neutron-induced cross sections were modified. Profiles calculated with lunar particle fluxes are much lower than experimental Canyon Diablo profiles. The cosmic ray exposure ages of most samples are near 540 m.y. 34 refs., 4 figs., 2 tabs.

  9. Search for extinct 36Cl: Vigarano CAIs, the Pink Angel from Allende, and a Ningqiang chondrule

    NASA Astrophysics Data System (ADS)

    Nakashima, Daisuke; Ott, Ulrich; Hoppe, Peter; El Goresy, Ahmed

    2008-12-01

    We have searched for excesses of 36S derived from the decay of extinct 36Cl in sodalite, a secondary Cl-rich mineral, in Ca-Al-rich inclusions (CAIs) from the Vigarano and Allende CV3 chondrites and in a chondrule from the Ningqiang carbonaceous chondrite. The presence of sodalite in two CAIs from Vigarano and its absence from surrounding CAI fragments suggests sodalite formation after CAI fragmentation. As for sodalite in the Allende Pink Angel CAI, oxygen isotopic compositions have been interpreted as indicative of high temperature interactions, thus suggesting formation prior to accretion to the parent body, probably in a nebular setting. Sodalite in the Ningqiang chondrule is considered to have formed via alkali-Ca exchange, which is believed to have occurred before accretion to the parent body. Sodalites in the Vigarano CAIs and in the Ningqiang chondrule show no clear evidence for the presence of radiogenic 36S. The inferred 2 σ upper limits for 36Cl/ 35Cl at the time of sodalite formation are 1.6 × 10 -6 (Vigarano CAIs) and 3.3 × 10 -6 (Ningqiang chondrule), respectively. In the Pink Angel CAI sodalite exhibits small 36S excesses which weakly correlate with 35Cl/ 34S ratios. The inferred 36Cl/ 35Cl ratio of (1.8 ± 2.2) × 10 -6 (2 σ error) is lower than that found by Hsu et al. [Hsu, W., Guan, Y., Leshin, L. A., Ushikubo, T. and Wasserburg, G. J. (2006) A late episode of irradiation in the early solar system: Evidence from extinct 36Cl and 26Al in meteorites. Astrophys. J. 640, 525-529], thus indicative of heterogeneous distribution of 36Cl in this CAI. Spallation reactions induced by energetic particles from the young Sun are suggested for the origin of 36Cl, similar to the case of 10Be. While 10Be appears to be present in roughly equal abundance in all studied CAIs, our study indicates the level of 36Cl abundances to be variable so that there seems to be no simple relationship between 10Be and 36Cl. This would be expected if trapped cosmic rays rather

  10. Temporal evolution of (36)Cl abundances in the Great Lakes.

    PubMed

    Poghosyan, Armen; Sturchio, Neil C

    2015-06-01

    The observed (36)Cl isotopic abundance in Great Lakes water decreases from west to east, with the highest (36)Cl/Cl ratio of 1332 × 10(-15) in Lake Superior and the lowest (36)Cl/Cl ratio of 151 × 10(-15) in Lake Erie, whereas the (36)Cl concentration ((36)Cl atoms/L) is lowest in Lake Superior and higher in the other Great Lakes. The (36)Cl concentration in Lake Superior is much higher than expected from normal atmospheric deposition over the basin, consistent with deposition of nuclear bomb-produced (36)Cl during 1952-1964. A conservative mass-balance model constrained by hydrological parameters and available (36)Cl fluence measurements predicts the (36)Cl abundances in the Great Lakes from 1945 to 2015, in excellent agreement with available data for Lakes Superior, Michigan, and Huron, but the model underestimates (36)Cl abundances for Lakes Erie and Ontario. However, assuming that (36)Cl demonstrates non-conservative behavior and is significantly retained in the drainage basins, a model incorporating a delayed input parameter successfully predicts observed (36)Cl concentrations in all of the Great Lakes.

  11. Cosmogenic 10Be, 21Ne and 36Cl in sanidine and quartz from Chilean ignimbrites

    NASA Astrophysics Data System (ADS)

    Ivy-Ochs, S.; Kober, F.; Alfimov, V.; Kubik, P. W.; Synal, H.-A.

    2007-06-01

    Our initial results indicate that three cosmogenic nuclides: 10Be, 21Ne and 36Cl can be analyzed in sanidine. To uncover complex exposure histories or marked changes in denudation rates over time several nuclides with different half-lives (or stable) must be measured. Because of its shorter half-life, the combination of 36Cl and a long-lived nuclide 10Be or stable nuclide 21Ne will provide more information than the pairs 10Be and 26Al or 10Be and 21Ne (in quartz). Sanidine (alkali feldspar) is a common high temperature mineral and often dominates the phenocryst assemblage in silicic to intermediate volcanic rocks. Bedrock surfaces studied come from the Oxaya (erupted 19-23 Ma) and Lauca (erupted 2.7 Ma) ignimbrites of northern Chile. Quartz and sanidine phenocrysts coexist; therefore, we can check the viability of sanidine through direct comparison with nuclide concentrations in quartz. In addition, as quartz has no target for 36Cl in significant abundance we show that the unique power of sanidine is that 36Cl can be measured. We have obtained very good agreement between 10Be and 21Ne concentrations measured in sanidine and coexisting quartz. No meteoric 10Be was apparent in these sanidines. Concentrations of all three nuclides in mineral separates from rock sample CN309 from the Lauca ignimbrite in the Western Cordillera agree well and correspond to minimum exposure ages of 30-50 ka. 10Be and 21Ne measured in both sanidine and quartz from three rock samples from the Oxaya ignimbrite (CN19, CN23, CN104a) in the Western Escarpment record low average landscape modification rates (<0.70 m/Ma) over the last several million years. In contrast, 36Cl data from sanidine in CN23 seem to indicate shorter minimum exposures and more rapid maximum erosion rates.

  12. Infiltration at yucca mountain, nevada, traced by 36Cl

    NASA Astrophysics Data System (ADS)

    Norris, A. E.; Wolfsberg, K.; Gifford, S. K.; Bentley, H. W.; Elmore, D.

    1987-11-01

    Measurements of chloride and 36Cl in soils from two locations near Yucca Mountain, Nevada, have been used to trace the infiltration of precipitation in this arid region. The results show that the 36Cl fallout from nuclear-weapons testing formed a well-defined peak at one location, with a maximum 36Cl/Cl ratio 0.5 m below the surface. The structure of the 36Cl bomb pulse at the other location was much more complex, and the quantity of 36Cl in the bomb pulse was < 1% of the 6 × 10 12 atoms {36Cl }/{m 2} in the bomb pulse at the first location. The data indicate hydrologic activity subsequent to the 36Cl bomb-pulse fallout at one location, but none at the other location.

  13. Medical application of 26Al

    NASA Astrophysics Data System (ADS)

    Steinhausen, C.; Gerisch, P.; Heisinger, B.; Hohl, Ch.; Kislinger, G.; Korschinek, G.; Niedermayer, M.; Nolte, E.; Dumitru, M.; Alvarez-Brückmann, M.; Schneider, M.; Ittel, T. H.

    1996-06-01

    Accelerator mass spectrometry (AMS) measurements with 26Al as tracer were performed in order to study the aluminium metabolism and anomalies in the human body and in rats. In particular, the differences between healthy volunteers and patients with renal failure were investigated. The obtained data points of 26Al in blood and urine were described by an open compartment model with three peripheral compartments. It was found that the minimum of peripheral compartments needed to describe 26Al concentrations in blood and urine over a time period of three years is at least three.

  14. Efficient 41Ca measurements for biomedical applications

    NASA Astrophysics Data System (ADS)

    Vockenhuber, C.; Schulze-König, T.; Synal, H.-A.; Aeberli, I.; Zimmermann, M. B.

    2015-10-01

    We present the performance of 41Ca measurements using low-energy Accelerator Mass Spectrometry (AMS) at the 500 kV facility TANDY at ETH Zurich. We optimized the measurement procedure for biomedical applications where reliability and high sample throughput is required. The main challenge for AMS measurements of 41Ca is the interfering stable isobar 41K. We use a simplified sample preparation procedure to produce calcium fluoride (CaF2) and extract calcium tri-fluoride ions (CaF3-) ions to suppress the stable isobar 41K. Although 41K is not completely suppressed we reach 41Ca/40Ca background level in the 10-12 range which is adequate for biomedical studies. With helium as a stripper gas we can use charge state 2+ at high transmission (∼50%). The new measurement procedure with the approximately 10 × improved efficiency and the higher accuracy due to 41K correction allowed us to measure more than 600 samples for a large biomedical study within only a few weeks of measurement time.

  15. Infiltration at Yucca Mountain, Nevada, traced by {sup 36}Cl

    SciTech Connect

    Norris, A.E.; Wolfsberg, K.; Gifford, S.K.; Bentley, H.W.; Elmore, D.

    1987-04-01

    Measurements of chloride and {sup 36}Cl in soils from two locations near Yucca Mountain, Nevada, have been used to trace the infiltration of precipitation in this arid region. The results show that the {sup 36}Cl fallout from nuclear weapons testing formed a well-defined peak at one location, with a maximum 0.5m below the surface. The structure of the {sup 36}Cl bomb pulse at the other location was much more complex, and quantity of {sup 36}Cl in the bomb pulse was <1% of the 6 x 10{sup 12} atoms {sup 36}Cl/m{sup 2} in the bomb pulse at the first location. The data indicate hydrologic activity subsequent to the {sup 36}Cl bomb pulse fallout at one location, but none at the other location. 11 refs.

  16. Detection of 36Cl with accelerator mass spectrometry

    NASA Astrophysics Data System (ADS)

    Jiang, Songsheng; Ma, Tiejung; Jiang, Shan; Yang, Bingfan; Wang, Xun; Huang, Qi

    1989-12-01

    An accelerator mass spectrometry (AMS) system based on the HI-13 tandem accelerator at the Institute of Atomic Energy (IAE) is described, and the first detection of 36Cl with our AMS system is reported. The electrostatic deflector completely rejects isotopic background, 35Cl and 37Cl. The ioinzation chamber distinguishs 36Cl from isobaric background, 36S. The measurement of 36Cl with two samples is presented.

  17. {sup 36}Cl bomb fallout at mid latitudes

    SciTech Connect

    Synal, H.A.; Beer, J.; Gaeggeler, H.

    1995-12-01

    Large amounts of {sup 36}Cl have been produced during the atmospheric test of nuclear weapons in the late fifties and early sixties. During this time the {sup 36}Cl fallout was about three orders of magnitudes larger than during previous times. The well defined {sup 36}Cl pulse has a great potential for hydrological investigations, especially as a tracer for groundwater studies. Detailed measurements of bomb produced {sup 36}Cl were carried out earlier on ice cores from Dye-3 (Greenland). To adopt the {sup 36}Cl pulse measured in Greenland as an input function to other locations its latitude dependence has to be known. So far, atmospheric transport models and the measured distribution of {sup 90}Sr and {sup 137}Cs fallout are used to estimate the latitude dependence of meteoric and bomb produced {sup 36}Cl fallout. In this contribution, {sup 36}Cl measurements on an ice core from an Alpine Glacier (Fiescher Horn, Switzerland) are presented. The results are compared with earlier measurements from a Greenland ice core and implications for the global {sup 36}Cl transport are discussed.

  18. Atmospheric transport of bomb-produced 36Cl

    NASA Astrophysics Data System (ADS)

    Synal, H.-A.; Beer, J.; Bonani, G.; Suter, M.; Wölfli, W.

    1990-12-01

    36Cl measurements have been made in an arctic ice core drilled near the Dye-3 site (65°11'N, 43°50'W). The samples analyzed cover the period between 1945 and 1985 with annual resolution. Due to the release of 36Cl to the atmosphere from nuclear bomb tests, the data shown a peak in the late fifties with 36Cl fallout rates about three orders of magnitude higher than expected from cosmic ray production. The time resolution is now precise enough to resolve the structure of the descending part of the fallout pattern. From the fallout rates obtained, a stratospheric residence time for bomb-produced 36Cl could be derived. A detailed interpretation of the data is done with a four-box atmospheric transport model. The large and well-defined 36Cl bomb pulse provides an excellent tracer for ground water studies.

  19. Determination of 36Cl in nuclear waste from reactor decommissioning.

    PubMed

    Hou, Xiaolin; Ostergaard, Lars Frøsig; Nielsen, Sven P

    2007-04-15

    An analytical method for the determination of 36Cl in nuclear waste such as graphite, heavy concrete, steel, aluminum, and lead was developed. Several methods were investigated for decomposing the samples. AgCl precipitation was used to separate 36Cl from the matrix elements, followed by ion-exchange chromatography to remove interfering radionuclides. The purified 36Cl was then measured by liquid scintillation counting. The chemical yield of chlorine, as measured by ICPMS, is above 70% and the decontamination factors for all interfering radionuclides are greater than 10(6). The detection limit of this analytical method for 36Cl is 14 mBq. The method has been used to determine 36Cl in heavy concrete, aluminum, and graphite from the Danish DR-2 research reactor.

  20. Determination of 36Cl in nuclear waste from reactor decommissioning.

    PubMed

    Hou, Xiaolin; Ostergaard, Lars Frøsig; Nielsen, Sven P

    2007-04-15

    An analytical method for the determination of 36Cl in nuclear waste such as graphite, heavy concrete, steel, aluminum, and lead was developed. Several methods were investigated for decomposing the samples. AgCl precipitation was used to separate 36Cl from the matrix elements, followed by ion-exchange chromatography to remove interfering radionuclides. The purified 36Cl was then measured by liquid scintillation counting. The chemical yield of chlorine, as measured by ICPMS, is above 70% and the decontamination factors for all interfering radionuclides are greater than 10(6). The detection limit of this analytical method for 36Cl is 14 mBq. The method has been used to determine 36Cl in heavy concrete, aluminum, and graphite from the Danish DR-2 research reactor. PMID:17375901

  1. A LOWER INITIAL ABUNDANCE OF SHORT-LIVED {sup 41}Ca IN THE EARLY SOLAR SYSTEM AND ITS IMPLICATIONS FOR SOLAR SYSTEM FORMATION

    SciTech Connect

    Liu, Ming-Chang; Chaussidon, Marc; Srinivasan, Gopalan; McKeegan, Kevin D.

    2012-12-20

    The short-lived radionuclide {sup 41}Ca plays an important role in constraining the immediate astrophysical environment and the formation timescale of the nascent solar system due to its extremely short half-life (0.1 Myr). Nearly 20 years ago, the initial ratio of {sup 41}Ca/{sup 40}Ca in the solar system was determined to be (1.41 {+-} 0.14) Multiplication-Sign 10{sup -8}, primarily based on two Ca-Al-rich Inclusions (CAIs) from the CV chondrite Efremovka. With an advanced analytical technique for isotopic measurements, we reanalyzed the potassium isotopic compositions of the two Efremovka CAIs and inferred the initial ratios of {sup 41}Ca/{sup 40}Ca to be (2.6 {+-} 0.9) Multiplication-Sign 10{sup -9} and (1.4 {+-} 0.6) Multiplication-Sign 10{sup -9} (2{sigma}), a factor of 7-10 lower than the previously inferred value. Considering possible thermal processing that led to lower {sup 26}Al/{sup 27}Al ratios in the two CAIs, we propose that the true solar system initial value of {sup 41}Ca/{sup 40}Ca should have been {approx}4.2 Multiplication-Sign 10{sup -9}. Synchronicity could have existed between {sup 26}Al and {sup 41}Ca, indicating a uniform distribution of the two radionuclides at the time of CAI formation. The new initial {sup 41}Ca abundance is 4-16 times lower than the calculated value for steady-state galactic nucleosynthesis. Therefore, {sup 41}Ca could have originated as part of molecular cloud materials with a free decay time of 0.2-0.4 Myr. Alternative possibilities, such as a last-minute input from a stellar source and early solar system irradiation, could not be definitively ruled out. This underscores the need for more data from diverse CAIs to determine the true astrophysical origin of {sup 41}Ca.

  2. High (36)Cl/Cl ratios in Chernobyl groundwater.

    PubMed

    Roux, Céline; Le Gal La Salle, Corinne; Simonucci, Caroline; Van Meir, Nathalie; Fifield, L Keith; Diez, Olivier; Bassot, Sylvain; Simler, Roland; Bugai, Dmitri; Kashparov, Valery; Lancelot, Joël

    2014-12-01

    After the explosion of the Chernobyl Nuclear Power Plant in April 1986, contaminated material was buried in shallow trenches within the exclusion zone. A (90)Sr plume was evidenced downgradient of one of these trenches, trench T22. Due to its conservative properties, (36)Cl is investigated here as a potential tracer to determine the maximal extent of the contamination plume from the trench in groundwater. (36)Cl/Cl ratios measured in groundwater, trench soil water and leaf leachates are 1-5 orders of magnitude higher than the theoretical natural (36)Cl/Cl ratio. This contamination occurred after the Chernobyl explosion and currently persists. Trench T22 acts as an obvious modern point source of (36)Cl, however other sources have to be involved to explain such contamination. (36)Cl contamination of groundwater can be explained by dilution of trench soil water by uncontaminated water (rainwater or deep groundwater). With a plume extending further than that of (90)Sr, radionuclide which is impacted by retention and decay processes, (36)Cl can be considered as a suitable tracer of contamination from the trench in groundwater provided that modern release processes of (36)Cl from trench soil are better characterized. PMID:25128774

  3. High (36)Cl/Cl ratios in Chernobyl groundwater.

    PubMed

    Roux, Céline; Le Gal La Salle, Corinne; Simonucci, Caroline; Van Meir, Nathalie; Fifield, L Keith; Diez, Olivier; Bassot, Sylvain; Simler, Roland; Bugai, Dmitri; Kashparov, Valery; Lancelot, Joël

    2014-12-01

    After the explosion of the Chernobyl Nuclear Power Plant in April 1986, contaminated material was buried in shallow trenches within the exclusion zone. A (90)Sr plume was evidenced downgradient of one of these trenches, trench T22. Due to its conservative properties, (36)Cl is investigated here as a potential tracer to determine the maximal extent of the contamination plume from the trench in groundwater. (36)Cl/Cl ratios measured in groundwater, trench soil water and leaf leachates are 1-5 orders of magnitude higher than the theoretical natural (36)Cl/Cl ratio. This contamination occurred after the Chernobyl explosion and currently persists. Trench T22 acts as an obvious modern point source of (36)Cl, however other sources have to be involved to explain such contamination. (36)Cl contamination of groundwater can be explained by dilution of trench soil water by uncontaminated water (rainwater or deep groundwater). With a plume extending further than that of (90)Sr, radionuclide which is impacted by retention and decay processes, (36)Cl can be considered as a suitable tracer of contamination from the trench in groundwater provided that modern release processes of (36)Cl from trench soil are better characterized.

  4. Distribution and Origin of 36Cl In Allende CAIs

    SciTech Connect

    Matzel, J P; Jacobsen, B; Hutcheon, I D; Krot, A N; Nagashima, K; Yin, Q; Ramon, E C; Weber, P; Wasserburg, G J

    2009-12-11

    The abundance of short-lived radionuclides (SLRs) in early solar system materials provide key information about their nucleosynthetic origin and can constrain the timing of early solar system events. Excesses of {sup 36}S ({sup 36}S*) correlated with {sup 35}Cl/{sup 34}S ratios provide direct evidence for in situ decay of {sup 36}Cl ({tau}{sub 1/2} {approx} 0.3 Ma) and have been reported in sodalite (Na{sub 8}Al{sub 6}Si{sub 6}O{sub 24}Cl{sub 2}) and wadalite (Ca{sub 6}Al{sub 5}Si{sub 2}O{sub 16}Cl{sub 3}) in CAIs and chondrules from the Allende and Ningqiang CV carbonaceous chondrites. While previous studies demonstrate unequivocally that {sup 36}Cl was extant in the early solar system, no consensus on the origin or initial abundance of {sup 36}Cl has emerged. Understanding the origin of {sup 36}Cl, as well as the reported variation in the initial {sup 36}Cl/{sup 35}Cl ratio, requires addressing when, where and how chlorine was incorporated into CAIs and chondrules. These factors are key to distinguishing between stellar nucleosynthesis or energetic particle irradiation for the origin of {sup 36}Cl. Wadalite is a chlorine-rich secondary mineral with structural and chemical affinities to grossular. The high chlorine ({approx}12 wt%) and very low sulfur content (<<0.01 wt%) make wadalite ideal for studies of the {sup 36}Cl-{sup 36}S system. Wadalite is present in Allende CAIs exclusively in the interior regions either in veins crosscutting melilite or in zones between melilite and anorthite associated with intergrowths of grossular, monticellite, and wollastonite. Wadalite and sodalite most likely resulted from open-system alteration of primary minerals with a chlorine-rich fluid phase. We recently reported large {sup 36}S* correlated with {sup 35}Cl/{sup 34}S in wadalite in Allende Type B CAI AJEF, yielding a ({sup 36}Cl/{sup 35}Cl){sub 0} ratio of (1.7 {+-} 0.3) x 10{sup -5}. This value is the highest reported {sup 36}Cl/{sup 35}Cl ratio and is {approx}5 times

  5. Measurement campaign for astrophysically relevant 36Cl production cross sections

    NASA Astrophysics Data System (ADS)

    Anderson, Tyler; Skulski, Michael; Ostdiek, Karen; Lu, Wenting; Beard, Mary; Collon, Philippe

    2015-10-01

    The short-lived radionuclide 36Cl (t1/2 = 0.301 Ma) is known to have existed in the Early Solar System (ESS), and evaluating its production sources can lead to better understanding of the processes taking place in ESS formation and their timescales. The x-wind production model is used to explain 36Cl production via solar energetic particles from the young Sun, but is lacking empirical data for many relevant reactions. Bowers et al. (2013) measured the cross section of 33S(α,p)36Cl at various energies in the range of 0.70-2.42 MeV/A, and found them to be systematically under predicted by statistical Hauser-Feshbach model codes TALYS and NON-SMOKER, highlighting the need for more empirical data for these cross sections. A recent paper by Mohr (2013) called these results in to question, prompting the re-measurement of the cross section for 33S(α,p)36Cl at new energies in the same energy range as Bowers et al. This talk will also discuss two further planned measurements of cross sections suggested by Bowers et al. to be the next most significant in 36Cl production.

  6. Accretion rate of extraterrestrial 41Ca in Antarctic snow samples

    NASA Astrophysics Data System (ADS)

    Gómez-Guzmán, J. M.; Bishop, S.; Faestermann, T.; Famulok, N.; Fimiani, L.; Hain, K.; Jahn, S.; Korschinek, G.; Ludwig, P.; Rodrigues, D.

    2015-10-01

    Interplanetary Dust Particles (IDPs) are small grains, generally less than a few hundred micrometers in size. Their main source is the Asteroid Belt, located at 3 AU from the Sun, between Mars and Jupiter. During their flight from the Asteroid Belt to the Earth they are irradiated by galactic and solar cosmic rays (GCR and SCR), thus radionuclides are formed, like 41Ca and 53Mn. Therefore, 41Ca (T1/2 = 1.03 × 105 yr) can be used as a key tracer to determine the accretion rate of IDPs onto the Earth because there are no significant terrestrial sources for this radionuclide. The first step of this study consisted to calculate the production rate of 41Ca in IDPs accreted by the Earth during their travel from the Asteroid Belt. This production rate, used in accordance with the 41Ca/40Ca ratios that will be measured in snow samples from the Antarctica will be used to calculate the amount of extraterrestrial material accreted by the Earth per year. There challenges for this project are, at first, the much longer time for the flight needed by the IDPs to travel from the Asteroid Belt to the Earth in comparison with the 41Ca half-life yields an early saturation for the 41Ca/40Ca ratio, and second, the importance of selecting the correct sampling site to avoid a high influx of natural 40Ca, preventing dilution of the 41Ca/40Ca ratio, the quantity measured by AMS.

  7. 41Ca - a possible neutron specific biomarker in tooth enamel

    NASA Astrophysics Data System (ADS)

    Wallner, A.; Arazi, A.; Faestermann, T.; Knie, K.; Korschinek, G.; Maier, H. J.; Nakamura, N.; Rühm, W.; Rugel, G.

    2004-08-01

    The measurement of long-lived radionuclides, produced by neutrons originating from the atomic-bomb explosions, offers the possibility to reconstruct neutron fluences to which survivors in Hiroshima and Nagasaki were exposed. The long-lived radionuclide, 41Ca (T1/2=103 000 years), is suggested here as a means for a retrospective determination of thermal neutron fluences, directly within the human body of a survivor. As proper material tooth enamel is proposed. The 41Ca signal in tooth enamel may be correlated with the exposure to A-bomb induced thermal neutron fluences, provided the natural background level of 41Ca/Ca is significantly lower. Therefore, tooth samples of unexposed survivors of the A-bomb explosions have been examined by means of accelerator mass spectrometry, in order to quantify the natural background level of 41Ca/Ca. Measured 41Ca/Ca ratios were confirmed to be as low as about 2 × 10-15. Thus, the A-bomb induced additional signal should be detectable for survivors at epidemiological relevant distances. Since tooth enamel had already been used as a dosemeter for gamma radiation from the A-bomb explosion, the detection of 41Ca in tooth enamel would allow, for the first time, an assessment of both, γ-ray and neutron exposures in the same biological material.

  8. Survey on Cosmogenic 26Al in Lewis Cliff Meteorites

    NASA Astrophysics Data System (ADS)

    Welten, K. C.; Alderliesten, C.; Lindner, L.

    1992-07-01

    levels of 56 +- 7 and 60 +- 7 for H and L chondrites, respectively [3], range up to 800 ka with an average of about 290 ka. Altogether this may indicate that the Lewis Cliff blue-ice region is a relatively old meteorite stranding area. This is supported by preliminary conclusions based on ^36Cl, measured in 8 Lewis Cliff meteorites [4]. However, it is likely that some of our terrestrial ages have been overestimated due to (i) lower ^26Al saturation values for meteorites with preatmospheric radii less than 20 cm [3] and (ii) low exposure ages, resulting in initial ^26Al levels below 90-95% of the saturation level. These effects make individual terrestrial age determinations solely based on ^26Al content speculative as long as additional cosmogenic nuclide data are lacking. Dramatic changes in the overall picture are not expected, because (i) we have measured relatively large samples with an average recovered weight of about 500 g (one 11-kg sample excluded) and (ii) anomalously low exposure ages occur in about only 5% of the cases [5,6]. Possible correlations between terrestrial age and place of find will be discussed. UNUSUAL EXPOSURE HISTORIES: We excluded samples with extremely low NTL (<1 krad) from the above discussion, because these may have been exposed to high SCR-fluxes due to smallperihelia orbits (<0.7 A.U.) [7]. This hypothesis is supported by LEW 87169 and 87143, which have extremely low NTL-values in combination with high ^26Al contents. PAIRING CRITERIA: In order to impose additional constraints on pairing possibilities we critically used--besides classification, location of find and TL-properties--the cosmogenic ^26Al and also the natural ^40K content of ordinary chondrites. As an example we will show that the 15 measured Lewis Cliff L6 chondrites are representing at least 10 separate falls. Acknowledgements. This work was performed with financial support from the "Nederlandse Organisatie voor Wetenschappelijk Onderzoek" (NWO). References: 1. Komura K. et

  9. Survey on Cosmogenic 26Al in Lewis Cliff Meteorites

    NASA Astrophysics Data System (ADS)

    Welten, K. C.; Alderliesten, C.; Lindner, L.

    1992-07-01

    levels of 56 +- 7 and 60 +- 7 for H and L chondrites, respectively [3], range up to 800 ka with an average of about 290 ka. Altogether this may indicate that the Lewis Cliff blue-ice region is a relatively old meteorite stranding area. This is supported by preliminary conclusions based on ^36Cl, measured in 8 Lewis Cliff meteorites [4]. However, it is likely that some of our terrestrial ages have been overestimated due to (i) lower ^26Al saturation values for meteorites with preatmospheric radii less than 20 cm [3] and (ii) low exposure ages, resulting in initial ^26Al levels below 90-95% of the saturation level. These effects make individual terrestrial age determinations solely based on ^26Al content speculative as long as additional cosmogenic nuclide data are lacking. Dramatic changes in the overall picture are not expected, because (i) we have measured relatively large samples with an average recovered weight of about 500 g (one 11-kg sample excluded) and (ii) anomalously low exposure ages occur in about only 5% of the cases [5,6]. Possible correlations between terrestrial age and place of find will be discussed. UNUSUAL EXPOSURE HISTORIES: We excluded samples with extremely low NTL (<1 krad) from the above discussion, because these may have been exposed to high SCR-fluxes due to smallperihelia orbits (<0.7 A.U.) [7]. This hypothesis is supported by LEW 87169 and 87143, which have extremely low NTL-values in combination with high ^26Al contents. PAIRING CRITERIA: In order to impose additional constraints on pairing possibilities we critically used--besides classification, location of find and TL-properties--the cosmogenic ^26Al and also the natural ^40K content of ordinary chondrites. As an example we will show that the 15 measured Lewis Cliff L6 chondrites are representing at least 10 separate falls. Acknowledgements. This work was performed with financial support from the "Nederlandse Organisatie voor Wetenschappelijk Onderzoek" (NWO). References: 1. Komura K. et

  10. 36Cl-36Ar Exposure Ages of Chondritic Metals

    NASA Astrophysics Data System (ADS)

    Graf, Th.; Caffee, M. W.; Finkel, R. C.; Marti, K.; Nishiizumi, K.; Ponganis, K. V.

    1995-09-01

    Metal separates were prepared to determine ^36Cl-^36Ar exposure ages for six H4 p.m. falls (with reported bulk exposure ages of 4 to 10Ma), for ten H5 a.m. falls (T(sub)e = 4-10 Ma) and for the Acapulco meteorite (T(^36Cl-^36Ar)= 5.7 Ma). This dating method uses production rate ratios P(^36Cl)/P(^36Ar) and is independent of the shielding-sensitive absolute production rates. It is also known that for protons the production rate ratio is rather insensitive to changes in the energy spectrum; the dependence of this ratio for secondary neutrons is at present less understood. First results were already reported [1]. The cosmic-ray-produced ^3He/^38Ar ratios show a bimodal distribution with two clusters at about 15 and about 9 (Fig. 1). About half of the ^3He is produced via ^3H which is known to diffuse in metal at relatively low temperatures. Therefore, Fig. 1 provides evidence for a quasi-continuous loss of ^3H from such metals. If this loss mechanism is due to solar heating, perihelia <1 AU are indicated for these meteorites. Losses are prominent for H5 a.m. falls, but not for H4 p.m. falls. The orbital implications are consistent with those already known from the time-of-fall parameter (p.m. falls / total falls) which was used in the selection of the H4,H5 sample sets [2]. The exposure age histograms of both H groups show the well known clusters at about 7 Ma. The width of the exposure age peaks differ, however, and the collisional break-up event can be further constrained. Except for Nassirah, all members of the H4 p.m. group fall into the range 7.0 +/- 0.3 Ma. Bulk rock ages (8.2-9.3 Ma) [3] as well as the ^36Cl-^36Ar age (8.3 Ma) of Nassirah are higher and may indicate that this meteorite does not belong to the collisional event. We observe a small but systematic difference in calculated exposure ages by the ^36Cl-^36Ar method, when compared with ages obtained by conventional noble gas production rates. This shift (about 10%) does not appear to be dependent on

  11. Progress on Atom Trap Trace Analysis of 41Ca

    NASA Astrophysics Data System (ADS)

    Li, Yimin; Bailey, Kevin; Du, Xu; Lu, Zheng-Tian; O'Connor, Thomas; Young, Linda

    2000-06-01

    A new method of ultrasensitive trace-isotope analysis, based on the techniques of laser cooling and trapping, has recently been used to detect the rare 81Kr atoms in atmospheric krypton samples [1]. We are working on applying this method to another important tracer - 41Ca, which has a half-life of 1.0 x 105 years and a natural isotope abundance of about 10-15. As a tracer, 41Ca is ideal for dating bones as old as a few hundred thousand years. This is an important era of human development, but too old for radiocarbon dating. It is also a useful medical tracer that can be applied to monitor bone-loss rates in the diagnosis and treatment of osteoporosis. We are setting up a MOT-system for the efficient trapping and counting of 41Ca atoms. The details of the system and experimental results will be presented at this poster. This work is supported by the U.S. Department of Energy, Nuclear Physics Division; L.Young is supported by the Office of Basic Energy Sciences, Division of Chemical Sciences (Contract W-31-109-ENG-38). [1] C.Y. Chen et. al., Science 286, 1139 (1999).

  12. SPI measurements of Galactic 26Al

    NASA Astrophysics Data System (ADS)

    Diehl, R.; Knödlseder, J.; Lichti, G. G.; Kretschmer, K.; Schanne, S.; Schönfelder, V.; Strong, A. W.; von Kienlin, A.; Weidenspointner, G.; Winkler, C.; Wunderer, C.

    2003-11-01

    The precision measurement of the 1809 keV gamma-ray line from Galactic 26Al is one of the goals of the SPI spectrometer on INTEGRAL with its Ge detector camera. We aim for determination of the detailed shape of this gamma-ray line, and its variation for different source regions along the plane of the Galaxy. Data from the first part of the core program observations of the first mission year have been inspected. A clear detection of the 26Al line at =~ 5-7 sigma significance demonstrates that SPI will deepen 26Al studies. The line intensity is consistent with expectations from previous experiments, and the line appears narrower than the 5.4 keV FWHM reported by GRIS, more consistent with RHESSI's recent value. Only preliminary statements can be made at this time, however, due to the multi-component background underlying the signal at =~ 40 times higher intensity than the signal from Galactic 26Al.

  13. {sup 36}Cl studies of water movements deep within unsaturated tuffs

    SciTech Connect

    Norris, A.E.; Bentley, H.W.; Cheng, S.; Kubik, P.W.; Sharma, P.; Gove, H.E.

    1990-05-01

    Measurements of {sup 36}Cl in cuttings from a borehole that was drilled 387 m into unsaturated tuffs indicate the possible detection of significant radioactive decay of cosmogenic {sup 36}Cl in two of the samples. However, the {sup 36}Cl/Cl ratio was found to vary with the amount of pulverization of the cuttings. Work is in progress to separate the {sup 36}Cl/Cl data into cosmogenic and in situ components. The cosmogenic component will be used to trace very slow water movements through the unsaturated zone. Bomb pulse {sup 36}Cl was observed as deep as 153 m, and this identification is not constrained by the problem with pulverization. This work shows the efficacy of {sup 36}Cl measurements for detecting modern water movements deep in the unsaturated zone. 9 refs., 3 tabs.

  14. Observable Proxies For 26 Al Enhancement

    SciTech Connect

    Fryer, Christopher L; Young, Patrick A; Ellinger, Carola I; Arnett, William D

    2008-01-01

    We consider the cospatial production of elements in supernova explosions to find observationally detectable proxies for enhancement of {sup 26}Al in supernova ejecta and stellar systems. Using four progenitors we explore a range of 1D explosions at different energies and an asymmetric 3D explosion. We find that the most reliable indicator of the presence of {sup 26}Al in unmixed ejecta is a very low S/Si ratio ({approx} 0.05). Production of N in O/S/Si-rich regions is also indicative. The biologically important element P is produced at its highest abundance in the same regions. Proxies should be detectable in supernova ejecta with high spatial resolution multi wavelength observations, but the small absolute abundance of material injected into a proto-planetary disk makes detection unlikely in existing or forming stellar/planetary systems.

  15. Evidence that 26Al Did Not Melt Asteroids

    NASA Astrophysics Data System (ADS)

    Wasson, J. T.

    2016-08-01

    26Al/27Al initial ratios in achondrites are much lower than expected if 26Al was the only heat source responsible for melting the parental materials. Impacts provided a substantial fraction of the heat.

  16. Determination of 36Cl in biological shield concrete using pyrohydrolysis and liquid scintillation counting.

    PubMed

    Itoh, Mitsuo; Watanabe, Kazuo; Hatakeyama, Mutsuo; Tachibana, Mitsuo

    2002-07-01

    A method for the determination of 36Cl in biological shield concrete of nuclear reactors was developed. Cl in the concrete sample was extracted quantitatively by pyrohydrolysis at 900 degrees C and recovered in Na2CO3 solution for subsequent measurement of 36Cl by liquid scintillation counting. WO3 was used as an accelerator in the pyrohydrolysis. The Cl extraction procedure was optimized by investigating experimental conditions with the use of ion chromatography and its recovery was evaluated by the analysis of the geochemical reference samples. The detection limit of 36Cl was 0.02 Bq g(-1) for a sample weight of 2 g. The relative standard deviation was 3-7% for the samples containing 0.5 Bq g(-1) levels of 36Cl. The method was applied to determine 36Cl in biological shield concrete of the Japan Power Demonstration Reactor. PMID:12173658

  17. The Hiroshima thermal-neutron discrepancy for (36)Cl at large distances. Part I: New (36)Cl measurements in granite samples exposed to A-bomb neutrons.

    PubMed

    Huber, Thomas; Rühm, Werner; Kato, Kazuo; Egbert, Stephen D; Kubo, Florian; Lazarev, Vitali; Nolte, Eckehart

    2005-10-01

    The long-lived radioisotope (36)Cl (half-life: 301,000 years) was measured in granite samples exposed to A-bomb neutrons at distances from 94 to 1,591 m from the hypocenter in Hiroshima, by means of accelerator mass spectrometry (AMS). Measured (36)Cl/Cl ratios decrease from 1.6 x 10(-10) close to the hypocenter to about 1-2 x 10(-13), at a distance of 1,300 m from the hypocenter. At this distance and beyond the measured (36)Cl/Cl ratios do not change significantly and scatter around values of 1-2 x 10(-13). These findings suggest that the (36)Cl had been predominantly produced by thermalized neutrons from the A-bomb via neutron capture on stable (35)Cl, at distances from the hypocenter smaller than about 1,200 m. At larger distances, however, confounding processes induced by cosmic rays or neutrons from the decay of uranium and thorium become important. This hypothesis is theoretically and experimentally supported in a consecutive paper. The results are compared to calculations that are based on the most recent dosimetry system DS02. Close to the hypocenter, measured (36)Cl/Cl ratios are lower than those calculated, while they are significantly higher at large distances from the hypocenter. If the contribution of the cosmic rays and of the neutrons from the decay of uranium and thorium in the sample was subtracted, however, no significant deviation from the DS02 calculations was observed, at those distances. Thus, the Hiroshima neutron discrepancy reported in the literature for (36)Cl for samples from large distances from the hypocenter, i.e., higher measured (36)Cl/Cl ratios than predicted by the previous dosimetry system DS86, was not confirmed.

  18. 182Hf-182W age dating of a 26Al-poor inclusion and implications for the origin of short-lived radioisotopes in the early Solar System.

    PubMed

    Holst, Jesper C; Olsen, Mia B; Paton, Chad; Nagashima, Kazuhide; Schiller, Martin; Wielandt, Daniel; Larsen, Kirsten K; Connelly, James N; Jørgensen, Jes K; Krot, Alexander N; Nordlund, Ake; Bizzarro, Martin

    2013-05-28

    Refractory inclusions [calcium-aluminum-rich inclusions, (CAIs)] represent the oldest Solar System solids and provide information regarding the formation of the Sun and its protoplanetary disk. CAIs contain evidence of now extinct short-lived radioisotopes (e.g., (26)Al, (41)Ca, and (182)Hf) synthesized in one or multiple stars and added to the protosolar molecular cloud before or during its collapse. Understanding how and when short-lived radioisotopes were added to the Solar System is necessary to assess their validity as chronometers and constrain the birthplace of the Sun. Whereas most CAIs formed with the canonical abundance of (26)Al corresponding to (26)Al/(27)Al of ∼5 × 10(-5), rare CAIs with fractionation and unidentified nuclear isotope effects (FUN CAIs) record nucleosynthetic isotopic heterogeneity and (26)Al/(27)Al of <5 × 10(-6), possibly reflecting their formation before canonical CAIs. Thus, FUN CAIs may provide a unique window into the earliest Solar System, including the origin of short-lived radioisotopes. However, their chronology is unknown. Using the (182)Hf-(182)W chronometer, we show that a FUN CAI recording a condensation origin from a solar gas formed coevally with canonical CAIs, but with (26)Al/(27)Al of ∼3 × 10(-6). The decoupling between (182)Hf and (26)Al requires distinct stellar origins: steady-state galactic stellar nucleosynthesis for (182)Hf and late-stage contamination of the protosolar molecular cloud by a massive star(s) for (26)Al. Admixing of stellar-derived (26)Al to the protoplanetary disk occurred during the epoch of CAI formation and, therefore, the (26)Al-(26)Mg systematics of CAIs cannot be used to define their formation interval. In contrast, our results support (182)Hf homogeneity and chronological significance of the (182)Hf-(182)W clock. PMID:23671077

  19. 182Hf-182W age dating of a 26Al-poor inclusion and implications for the origin of short-lived radioisotopes in the early Solar System.

    PubMed

    Holst, Jesper C; Olsen, Mia B; Paton, Chad; Nagashima, Kazuhide; Schiller, Martin; Wielandt, Daniel; Larsen, Kirsten K; Connelly, James N; Jørgensen, Jes K; Krot, Alexander N; Nordlund, Ake; Bizzarro, Martin

    2013-05-28

    Refractory inclusions [calcium-aluminum-rich inclusions, (CAIs)] represent the oldest Solar System solids and provide information regarding the formation of the Sun and its protoplanetary disk. CAIs contain evidence of now extinct short-lived radioisotopes (e.g., (26)Al, (41)Ca, and (182)Hf) synthesized in one or multiple stars and added to the protosolar molecular cloud before or during its collapse. Understanding how and when short-lived radioisotopes were added to the Solar System is necessary to assess their validity as chronometers and constrain the birthplace of the Sun. Whereas most CAIs formed with the canonical abundance of (26)Al corresponding to (26)Al/(27)Al of ∼5 × 10(-5), rare CAIs with fractionation and unidentified nuclear isotope effects (FUN CAIs) record nucleosynthetic isotopic heterogeneity and (26)Al/(27)Al of <5 × 10(-6), possibly reflecting their formation before canonical CAIs. Thus, FUN CAIs may provide a unique window into the earliest Solar System, including the origin of short-lived radioisotopes. However, their chronology is unknown. Using the (182)Hf-(182)W chronometer, we show that a FUN CAI recording a condensation origin from a solar gas formed coevally with canonical CAIs, but with (26)Al/(27)Al of ∼3 × 10(-6). The decoupling between (182)Hf and (26)Al requires distinct stellar origins: steady-state galactic stellar nucleosynthesis for (182)Hf and late-stage contamination of the protosolar molecular cloud by a massive star(s) for (26)Al. Admixing of stellar-derived (26)Al to the protoplanetary disk occurred during the epoch of CAI formation and, therefore, the (26)Al-(26)Mg systematics of CAIs cannot be used to define their formation interval. In contrast, our results support (182)Hf homogeneity and chronological significance of the (182)Hf-(182)W clock.

  20. The distribution of meteoric 36Cl/Cl in the United States: A comparison of models

    USGS Publications Warehouse

    Moysey, S.; Davis, S.N.; Zreda, M.; Cecil, L.D.

    2003-01-01

    The natural distribution of 36Cl/Cl in groundwater across the continental United States has recently been reported by Davis et al. (2003). In this paper, the large-scale processes and atmospheric sources of 36Cl and chloride responsible for controlling the observed 36Cl/Cl distribution are discussed. The dominant process that affects 36Cl/Cl in meteoric groundwater at the continental scale is the fallout of stable chloride from the atmosphere, which is mainly derived from oceanic sources. Atmospheric circulation transports marine chloride to the continental interior, where distance from the coast, topography, and wind patterns define the chloride distribution. The only major deviation from this pattern is observed in northern Utah and southern Idaho where it is inferred that a continental source of chloride exists in the Bonneville Salt Flats, Utah. In contrast to previous studies, the atmospheric flux of 36Cl to the land surface was found to be approximately constant over the United States, without a strong correlation between local 36Cl fallout and annual precipitation. However, the correlation between these variables was significantly improved (R 2=0.15 to R 2=0.55) when data from the southeastern USA, which presumably have lower than average atmospheric 36Cl concentrations, were excluded. The total mean flux of 36Cl over the continental United States and total global mean flux of 36Cl are calculated to be 30.5??7.0 and 19.6??4.5 atoms m-2 s-1, respectively. The 36Cl/Cl distribution calculated by Bentley et al. (1996) underestimates the magnitude and variability observed for the measured 36Cl/Cl distribution across the continental United States. The model proposed by Hainsworth (1994) provides the best overall fit to the observed 36Cl/Cl distribution in this study. A process-oriented model by Phillips (2000) generally overestimates 36Cl/Cl in most parts of the country and has several significant local departures from the empirical data.

  1. 182Hf–182W age dating of a 26Al-poor inclusion and implications for the origin of short-lived radioisotopes in the early Solar System

    PubMed Central

    Holst, Jesper C.; Olsen, Mia B.; Paton, Chad; Nagashima, Kazuhide; Schiller, Martin; Wielandt, Daniel; Larsen, Kirsten K.; Connelly, James N.; Jørgensen, Jes K.; Krot, Alexander N.; Nordlund, Åke; Bizzarro, Martin

    2013-01-01

    Refractory inclusions [calcium–aluminum-rich inclusions, (CAIs)] represent the oldest Solar System solids and provide information regarding the formation of the Sun and its protoplanetary disk. CAIs contain evidence of now extinct short-lived radioisotopes (e.g., 26Al, 41Ca, and 182Hf) synthesized in one or multiple stars and added to the protosolar molecular cloud before or during its collapse. Understanding how and when short-lived radioisotopes were added to the Solar System is necessary to assess their validity as chronometers and constrain the birthplace of the Sun. Whereas most CAIs formed with the canonical abundance of 26Al corresponding to 26Al/27Al of ∼5 × 10−5, rare CAIs with fractionation and unidentified nuclear isotope effects (FUN CAIs) record nucleosynthetic isotopic heterogeneity and 26Al/27Al of <5 × 10−6, possibly reflecting their formation before canonical CAIs. Thus, FUN CAIs may provide a unique window into the earliest Solar System, including the origin of short-lived radioisotopes. However, their chronology is unknown. Using the 182Hf–182W chronometer, we show that a FUN CAI recording a condensation origin from a solar gas formed coevally with canonical CAIs, but with 26Al/27Al of ∼3 × 10−6. The decoupling between 182Hf and 26Al requires distinct stellar origins: steady-state galactic stellar nucleosynthesis for 182Hf and late-stage contamination of the protosolar molecular cloud by a massive star(s) for 26Al. Admixing of stellar-derived 26Al to the protoplanetary disk occurred during the epoch of CAI formation and, therefore, the 26Al–26Mg systematics of CAIs cannot be used to define their formation interval. In contrast, our results support 182Hf homogeneity and chronological significance of the 182Hf–182W clock. PMID:23671077

  2. High temperature pyrolysis to extract 36Cl for Accelerator Mass Spectrometry measurements

    NASA Astrophysics Data System (ADS)

    Cornett, R. J.; Andrews, H. R.; Chant, L.; Chaput, T.; Imahori, Y.; Jirovec, J.; Kramer, S.; Koslowsky, V. T.; Milton, G. M.; Milton, J. C. D.

    1996-10-01

    36Cl and stable Cl were extracted from solids by high temperature pyrolysis and then analyzed by Accelerator Mass Spectrometry (AMS). Cl was quantitatively extracted from rock, ore, vegetation and freshwater sediments in samples weighing from 100 mg to 2 g. 36Cl:Cl activity ratios measured following Cl extraction by pyrolysis agreed with those measured following Cl extraction by acid leaching. The simple pyrolysis extraction has the additional advantages that stable Cl - can be measured on the same sample along with other anions, the 36Cl:Cl ratio can be adjusted by diluting the known Cl - concentration in the collection solution to control the activity of 36Cl in the target and the potential interference of 36S can also be assessed prior to the AMS measurements.

  3. Direct Determination of the Half-Life of ^4^1Ca

    NASA Astrophysics Data System (ADS)

    Jörg, G.; Amelin, Y.; Kossert, K.; v. Gostomski, C. L.

    2012-03-01

    The half-life of ^4^1Ca is determined at 9937 ± 146 years using double spike isotope dilution TIMS, and liquid scintillation counting using triple-to-double coincidence ratio method on a radiochemically pure, carrier-free ^4^1Ca.

  4. 26Al uptake and accumulation in the rat brain

    NASA Astrophysics Data System (ADS)

    Yumoto, S.; Nagai, H.; Imamura, M.; Matsuzaki, H.; Hayashi, K.; Masuda, A.; Kumazawa, H.; Ohashi, H.; Kobayashi, K.

    1997-03-01

    To investigate the cause of Alzheimer's disease (senile dementia), 26Al incorporation in the rat brain was studied by accelerator mass spectrometry (AMS). When 26Al was injected into healthy rats, a considerable amount of 26Al entered the brain (cerebrum) through the blood-brain barrier 5 days after a single injection, and the brain 26Al level remained almost constant from 5 to 270 days. On the other hand, the level of 26Al in the blood decreased remarkably 75 days after injection. Approximately 89% of the 26Al taken in by the brain cell nuclei bound to chromatin. This study supports the theory that Alzheimer's disease is caused by irreversible accumulation of aluminium (Al) in the brain, and brain cell nuclei.

  5. Cosmogenic {sup 36}Cl accumulation in unstable landforms 2. Simulations and measurements on eroding moraines

    SciTech Connect

    Zreda, M.G.; Phillips, F.M.; Elmore, D.

    1994-11-01

    Cosmogenic {sup 36}Cl ages of boulders from late Pleistocene moraines in Bishop Creek, Sierra Nevada, California, provided valuable details about {sup 36}Cl surface exposure dating and the nature of post depositional processes that modify glacial landforms. The natural variability of the apparent {sup 36}Cl ages among morainal boulders is due to soil erosion and gradual exposure of boulders at the surface. Two mechanisms are responsible for the resulting distributions of the apparent {sup 36}Cl ages. Variability of the initial burial depth among boulders and variability in the chemical composition of boulders from the same depth both result in different {sup 36}Cl ages due to the dependence of the depth production profile on the boulder chemistry. The authors measured cosmogenic {sup 36}Cl in boulders from a late Pleistocene moraine. The distribution of the calculated apparent ages allowed them to calculate the true age of 85 kyr and the erosion rate of 570 g cm{sup -2}. These results are in excellent agreement with independently estimated values of 87 kyr and 600 g cm{sup -2} for the age and erosion depth, respectively. These results indicate that the model satisfactorily simulates effects of erosion processes and can thus aid in surface exposure dating of eroding landforms.

  6. Comparison of 36Cl and 3He measurements in glacial surfaces on the tropical Altiplano (Cerro Tunupa volcano, 20°S)

    NASA Astrophysics Data System (ADS)

    Schimmelpfennig, Irene; Blard, Pierre-Henri; Lavé, Jérôme; Benedetti, Lucilla; Aster Team

    2016-04-01

    The combination of two or more cosmogenic nuclides measured in the same rock samples allow complex landscape exposure histories to be quantified, due to the nuclide-specific production and decay rates. In supposedly simple exposure scenarios, such as moraine chronologies, the use of more than one nuclide can also help identify outliers caused by geomorphological bias (e.g. "inheritance") or analytical problems (e.g. nuclide loss or contamination during chemical extraction). The two cosmogenic in situ nuclides 3He and 36Cl are potentially very useful to be simultaneously measured in quartz-lacking lithologies, but their application is more challenging than that of combined 10Be and 26Al measurements, which are routinely employed in quartz-bearing rocks. This is, amongst other things, because the production of 3He and 36Cl depend on various compositional factors. Therefore, 3He and 36Cl have rarely been measured in the same samples so far. Here, we present 36Cl measurements in plagioclases extracted from four moraine boulders and one roche moutonnée on the southern flank of Cerro Tunupa volcano, located in the tropical Bolivian Andes (3800-4500 m, 20°S). In pyroxenes of these samples, 3He has previously been measured to gain insights into the local deglaciation history and climate conditions about 15 kyr ago during the Lake Tauca highstand (Blard et al., 2009, 2013). The ages calculated from the measured 3He and 36Cl concentrations of the 5 samples range from 12 kyr to 180 kyr and are generally in good agreement. The good age agreement of a boulder surface (TU-1C) that is significantly older than the other boulder ages from this moraine confirm the suspicion, that it was exposed to cosmic radiation previous to its last deposition (Blard et al., 2009, 2013). In contrast, the 36Cl age of the roche moutonnée surface (TU2) is significantly younger than the corresponding 3He age, but fits well with the adjacent moraine mean age. It thus arises the question if the 3He

  7. Quality assurance and 36Cl program at SUERC: Implications to landscape evolution research

    NASA Astrophysics Data System (ADS)

    Wilcken, Klaus; Freeman, Stewart; Phillips, Richard; Schnabel, Christoph; Binnie, Steven; Dougans, Andrew; Dunai, Tibor; Cowie, Patience; Roberts, Gerald

    2010-05-01

    In situ-produced cosmogenic nuclei, made by cosmic ray induced nuclear reactions cumulatively on exposed surfaces, are natural chronometers and valuable tools for environmental and geological research. Cosmogenic 36Cl (t1-2=3e5 yr) is dominantly produced in spallation reactions on Ca and K, and via neutron capture on 35Cl, and hence is applicable to a range of lithologies for studying events within the last 1 Myr or so. The different 36Cl production mechanisms result in versatility but also challenging data interpretation when unravelling the measured 36Cl concentrations. The main difficulty in utilising 36Cl for environmental and geological research arises from the stable isobar 36S. However, if high enough ion energies are available, these two isotopes can be separated based upon their different rate of energy loss in matter. This has typically required large (10-15 MV) legacy nuclear physics particle accelerators but recently it has been shown that sufficient separation can be achieved with much lower ion energies than before (~30 MeV); the detector resolution being improved by using uniform thin (~30 nm) Silicon rich Nitride membranes as a detector window to minimise energy losses and peak broadening. As a consequence, measurements can now be done with 5 MV, or even smaller, modern accelerator mass spectrometers utilising gas stripping to produce the highest possible quality beams. Accordingly a new class of commercial purpose-build 5-6 MV 36Cl-capable spectrometers is being deployed around the globe with additional measurement capacity greater than that of the installed base. This should increase accessibility and promote wider and more varied 36Cl use. However, laborious sample preparation chemistry and production rate uncertainties remain difficulties. An example 36Cl programme utilising the 5 MV accelerator mass spectrometer at SUERC will be presented. Our internal quality assurance program shows that no external uncertainty beyond 3% counting statistics is

  8. A study of 36Cl production in the early Solar System

    NASA Astrophysics Data System (ADS)

    Bowers, Matthew R.

    Short-lived radionuclides (SLRs) with lifetimes tau < 100 Ma are known to have been extant when the Solar System formed 4.568 billion years ago from meteoritic studies of their decay products. Identifying the origins of SLRs can provide insight into the origins and timescales of our Solar System and the processes that shaped it. There are two proposed production scenarios for the origins of SLRs with tau < 5 Ma. Freshly synthesized material could be incorporated in the Solar System by a nearby stellar source (e.g., supernova, AGB star, Wolf-Rayet star), or SLRs could have also been produced by the bombardment of gas and dust by solar energetic particles (SEP) emitted by our young Sun. The origin of extinct 36Cl (t1/2 = 0.301 Ma) in the early Solar System is thought to have been produced by local particle irradiation. However the models that attempt to recreate the production of 36Cl in the early Solar System lack experimental data for the nuclear reactions considered. The first measurement of the 33S(alpha,p) 36Cl reaction, an important reaction in the production of 36Cl , was performed. The cross section measurement was performed by bombarding a target and collecting the recoiled 36Cl atoms produced in the reaction, chemically processing the samples, and measuring the 36Cl/Cl concentration of the samples with accelerator mass spectrometry (AMS). The cross section was measured at six energies that ranged from 0.70 up to 2.42 MeV/A, within the SEP energy spectrum. The experimental results were found to be systematically higher than the predicted cross sections. However, the deviations lead to < 7 % increase in total production of 36Cl under the x-wind model. From the experimental measurement and a study of the other reactions' contributions to 36Cl production, 36Cl could have been produced close to the protoSun by reactions on Ca targets using the x-wind model, or in a late-stage irradiation event on a volatile-rich reservoir by 3He and alpha reactions on S targets.

  9. Further Exploration of the 33S(α,p)36Cl Reaction Cross Section

    NASA Astrophysics Data System (ADS)

    Skulski, Michael; Anderson, Tyler; Beard, Mary; Collon, Philippe; Lu, Wenting; Ostdiek, Karen

    2015-10-01

    Short-lived radionuclides (SLRs) are extant from the Early Solar System (ESS) and useful for dating products of ESS processes. The SLR 36Cl was potentially produced by solar energetic particles incident on gas and dust in the protoplanetary disk. Measurement of the cross section of the reaction 33S(α,p)36Cl, which contributes significantly to the abundance of 36Cl, is an important input in solar irradiation models regarding the determination of elemental abundances, and is thus of great interest. In a previous measurement performed by Bowers et al. (2013), the cross section of this reaction was studied using a combination of activation of a 4He gas cell and analyzing the produced 36Cl via Accelerator Mass Spectrometry (AMS) over an energy range of 0.7 - 2.42 MeV/A. The result of this measurement was a significantly higher yield of 36Cl than predicted by Hauser-Feshbach cross section calculations. In light of the paper by Mohr (2013), the same activation was repeated at the University of Notre Dame at intermediate energies to study the cross section further, using the same combination of activation and AMS. The results of this measurement will be presented.

  10. Study of nuclear reactions producing 36Cl by micro-AMS

    NASA Astrophysics Data System (ADS)

    Luís, H.; Jesus, A. P.; Fonseca, M.; Cruz, J.; Galaviz, D.; Franco, N.; Alves, E.

    2016-01-01

    36Cl is one of several short to medium lived isotopes (as compared to the earth age) whose abundances at the earlier solar system may help to clarify its formation process. There are two generally accepted possible models for the production of this radionuclide: it originated from the ejecta of a nearby supernova (where 36Cl was most probably produced in the s-process by neutron irradiation of 35Cl) and/or it was produced by in-situ irradiation of nebular dust by energetic particles (mostly, p, a, 3He -X-wind irradiation model). The objective of the present work is to measure the cross section of the 37Cl(p,d)36Cl and 35Cl(d,p)36Cl nuclear reactions, by measuring the 36Cl content of AgCl samples (previously bombarded with high energy protons and deuterons) with AMS, taking advantage of the very low detection limits of this technique for chlorine measurements. For that, the micro-AMS system of the LF1/ITN laboratory had to be optimized for chlorine measurements, as to our knowledge this type of measurements had never been performed in such a system (AMS with micro-beam). Here are presented the first results of these developments, namely the tests in terms of precision and reproducibility that were done by comparing AgCl blanks irradiated at the Portuguese National Reactor with standards produced by the dilution of the NIST SRM 4943 standard material.

  11. Measurement of 26Al for atmospheric and climate research and the potential of 26Al/ 10Be ratios

    NASA Astrophysics Data System (ADS)

    Auer, M.; Kutschera, W.; Priller, A.; Wagenbach, D.; Wallner, A.; Wild, E. M.

    2007-06-01

    The measurement of the paired cosmogenic radionuclides 26Al and 10Be in environmental samples has potential applications in atmospheric and climate research. For this study, we report the first measurements of the 26Al/10Be atomic ratio in tropospheric aerosol samples from sites in Europe and Antarctica performed at the Vienna Environmental Research Accelerator (VERA). These initial results show that the 26Al/10Be atomic ratio in tropospheric aerosols averages 1.78 × 10-3 and does not vary significantly between the different locations. We also report results of systematic investigations of the ionization and detection efficiency which we performed to improve the measurement precision for 26Al by AMS. Maximum detection efficiencies of up to 9 × 10-4 (in units of 26Al atoms detected/initial) were achieved for chemically pure Al2O3, while for atmospheric samples we reached efficiencies of up to 2.2 × 10-4.

  12. Study on bone resorption behavior of osteoclast under drug effect using 41Ca tracing

    NASA Astrophysics Data System (ADS)

    Kejun, Dong; Liyan, Lu; Ming, He; Yinggen, Ouyang; Yan, Xue; Chaoli, Li; Shaoyong, Wu; Xianggao, Wang; Hongtao, Shen; Jianjun, Gao; Wei, Wang; Dafu, Chen; Yonggang, Xing; Jian, Yuan; Shan, Jiang

    2013-01-01

    The mechanisms governing calcium fluxes during bone remodeling processes in Osteoporosis (OP) patients are poorly known. Understanding the changes of Osteoclasts (OC) during this dynamic transition is important to prevent and cure OP. The exploration of long-lived 41Ca (T1/2 = 1.04 × 105 years) tracer combined with AMS measurements leads to the possibility of monitoring the bone resorption behavior of OC in OP patients. In this work, the behavior of OC with the administration of Strontium Ranelate (SR), a drug for OP, was studied by using 41Ca labeled hydroxyapatite (HAP) to simulate the bone. AMS on the HI-13 tandem accelerator at CIAE was used to determine trace amounts of 41Ca. The results show that the technique of 41Ca tracing with AMS can be used to quantitatively monitor the behavior of OC in bone resorption under the effects of drugs. Experimental details and preliminary results will be presented.

  13. The sup 36 Cl ages of the brines in the Magadi-Natron basin, east Africa

    SciTech Connect

    Kaufman, A.; Margaritz, M.A.; Hollos, G. ); Paul, M.; Boaretto, E. ); Hillaire-Marcel, C. ); Taieb, M. )

    1990-10-01

    The depression in the East African Rift which includes both Lake Magadi and Lake Natron forms a closed basin within which almost all the dissolved chloride originates in precipitation, since there is no important source of very ancient sedimentary chloride. This provides an ideal setting for the evaluation of the {sup 36}Cl methodology as a geochemical and hydrological tracer. The main source of recent water, as represented by the most dilute samples measured, is characterized by a {sup 36}Cl/Cl ratio of 2.5 {times} 10{sup {minus}14}, in agreement with the calculated value expected in precipitation. Surface evaporation increases the chlorinity of the local freshwater inflow by about a factor of 110 without changing the isotopic ratio, indicating that little chloride enters the system in the form of sediment leachate. A second type of brine found in the basin occurs in a hot deep groundwater reservoir and is characterized by lower {sup 36}Cl/Cl ratios (<1.2 {times} 10{sup {minus}14}). By comparing this value with the 2.5 {times} 10{sup {minus}14} in recent recharge, one obtains an approximate salt accumulation age of 760 Ka which is consistent with thee time of the first appearance of the lake. These older brines also have lower {sup 18}O and {sup 2}H values which indicate that they were recharged during a climatically different era. The {sup 36}Cl/Cl ratios in the inflowing waters and in the accumulated brine, together with the known age of the Lake Magadi basin, may be used to estimate the importance of the hypogene and epigene, as opposed to the meteoric, mode of {sup 36}Cl production. Such a calculation shows that the hypogene and epigene processes together contribute less than 6% of the total {sup 36}Cl present in the lake.

  14. The study of skeletal calcium metabolism with 41Ca and 45Ca

    NASA Astrophysics Data System (ADS)

    Freeman, Stewart P. H. T.; Beck, Belinda; Bierman, June M.; Caffee, Marc W.; Heaney, Robert P.; Holloway, Leah; Marcus, Robert; Southon, John R.; Vogel, John S.

    2000-10-01

    The living skeleton can be labeled for life by the administration of radiologically trivial amounts of 41Ca tracer. After initial elimination of tracer from the readily exchangeable calcium pools subsequent skeletal calcium turnover maintains and modulates the urine 41Ca content. Uniquely, bone calcium metabolism may then be studied with tracer in near equilibrium with the body's calcium and resorbing calcium directly measured by accelerator mass spectrometry (AMS) of excreta. Our experiments with 25 41Ca labeled subjects demonstrate excellent diurnal stability and remarkable response to intervention of the urine signal. Thus the tracer method may prove a competitive means of measuring the effects of antiresorptive osteoporosis treatments, for therapy development or even clinical monitoring. Novel studies of long-term skeletal evolution are also possible. We realize that routinely administered short-lived calcium radiotracers contain 41Ca impurities and that thousands of experimental participants have been historically inadvertently 41Ca labeled. The 41Ca urine index might now rapidly further be characterized by contemporary measurements of these one-time subjects, and with their by now thoroughly skeleton-equilibrated tracer they might be ideal participants in other new experiments. We are also investigating 45Ca AMS. It may prove preferable to label the skeleton with this radiotracer already familiar to bioscientists, but new to AMS.

  15. Probing Galactic 26Al with Exotic Ion Beams

    SciTech Connect

    Chen, Alan A.

    2006-07-12

    The goal of understanding the production of galactic 26Al brings together progress in nuclear astrophysics from observations, theory, meteoritics, and laboratory experiments. In the case of experimental work, nuclear reactions involving unstable isotopes are being studied to elucidate the production of 26Al in stellar explosive nucleosynthesis. We discuss a direct measurement of the 26Al(p,{gamma})27Si reaction with the DRAGON collaboration at TRIUMF, and a measurement of 25Al+p elastic scattering with the CRIB (CNS-U.Tokyo) collaboration, toward constraining the 25Al(p,{gamma})26Si reaction.

  16. Probing Galactic 26Al with Exotic Ion Beams

    NASA Astrophysics Data System (ADS)

    Chen, Alan A.

    2006-07-01

    The goal of understanding the production of galactic 26Al brings together progress in nuclear astrophysics from observations, theory, meteoritics, and laboratory experiments. In the case of experimental work, nuclear reactions involving unstable isotopes are being studied to elucidate the production of 26Al in stellar explosive nucleosynthesis. We discuss a direct measurement of the 26Al(p,γ)27Si reaction with the DRAGON collaboration at TRIUMF, and a measurement of 25Al+p elastic scattering with the CRIB (CNS-U.Tokyo) collaboration, toward constraining the 25Al(p,γ)26Si reaction.

  17. Production rates of 36Cl in basalts from the calibration site of Fuerteventura, Canary Islands

    NASA Astrophysics Data System (ADS)

    Mai, K.

    2009-09-01

    Age determination based on cosmogenic nuclides is an important tool to investigate landscape development and age relations of geologically very young materials. The aim of this study is to contribute data to establish age determination of the basis of cosmogenic 36Cl production as a generally reliable method. 36Cl is a radionuclide that is in situ produced by cosmic radiation at the earth surface. It is formed by spallation from Ca, K, Ti, and Fe, by thermal neutron capture in 35Cl, and by muogenic production from Ca and K. The concentration of the cosmogenic nuclide provides a measure of the exposure age of the surface, but also of the exposure history which may include periods of burial or erosion. Several factors such as the geographic position of the site, the topographic shielding of the surrounding hillside and the sample thickness or sampling depth influence the effective amount of radiation hitting the surface and are taken into account by applying appropriate scaling factors. Basalt samples from the mid-latitude, low altitude calibration site of Fuerteventura, Canary Islands were collected and the production rates of 36Cl were determined. Geologically young samples covering an age range of approximately 50 to 400 ka could be collected from a number of flows, which suit the time span that can be covered with 36Cl age determination. The age was independently determined with the 40Ar/39Ar method. From nine lava flows 7 or 8 samples were collected whose surface structures indicated as little erosion as possible. ICP and XRF measurements proved that the basalts were very similar in chemical composition. The preparation of the AMS samples followed generally the procedure established by Stone et al. (1996b). The measurements were performed at the AMS facility at the University of Utrecht. From the results of the measurements total chlorine concentrations the amount of 36Cl, and the production rates were deduced. The high variability of the production rates for

  18. Radiocarbon dating and the 36Cl/Cl evolution of three Great Artesian Basin wells at Dalhousie, South Australia

    NASA Astrophysics Data System (ADS)

    Abu Risha, Usama A.

    2016-06-01

    The use of 14C (half-life = 5,730 years) in modeling the evolution of the 36Cl/Cl ratios in groundwater is reported for the first time. The complexity of the Cl-36Cl system due to the occurrence of different Cl and 36Cl sources and the difficulty of the determination of the initial groundwater 36Cl/Cl ratios have raised concerns about the reliability of using 36Cl (half-life = 301 thousand years, a) as a groundwater-dating tool. This work uses groundwater 14C age as a calibrating parameter of the Cl-36Cl/Cl decay-mixing models of three wells from the southwestern Great Artesian Basin (GAB), Australia. It aims to allow for the different sources of Cl and 36Cl in the southwestern GAB aquifer. The results show that the initial Cl concentrations range from 245 to 320 mg/l and stable Cl is added to groundwater along flowpaths at rates ranging from 1.4 to 3.5 mg/l/ka. The 36Cl content of the groundwater is assumed to be completely of atmospheric origin. The samples have different Cl-36Cl/Cl mixing-decay models reflecting recharge under different conditions as well as the heterogeneity of the aquifer.

  19. Shielding Effects on 10Be and 26Al in Diogenites

    NASA Astrophysics Data System (ADS)

    Welten, K. C.; Lindner, L.; van der Borg, K.; Loeken, Th.; Schultz, L.

    1995-09-01

    Due to the attenuation of primary particles and the variations in secondary part fluxes with depth, production rates of cosmogenic nuclides are affected by the s shape of the irradiated object. The effects of shielding conditions on the produduction rates of noble gases can be estimated on the basis of the cosmogenic 22Ne/21Ne r [1]. For the production of cosmogenic radionuclides, shielding studies mainly fo on large meteorites like St. Severin [2], Knyahinya [3], Chico [4] and Jilin [5] estimated preatmospheric radii between 25 and 85 cm. The 10Be and 26Al production were also measured in three smaller meteorites, but the cosmogenic 22Ne/21Ne rat were obscured by large amounts of trapped neon [6]. Therefore we carried out a systematic study on the 10Be and 26Al activities as a function of the 22Ne/21Ne in 7 non-Antarctic and 15 Antarctic diogenite samples. Diogenites show exposure long enough (>10 Ma) to have reached saturation levels for 10Be and 26Al and are similar to ordinary chondrites with respect to the target element composition fo production of 10Be, 26Al and Ne isotopes. The measured 10Be and 26Al activities were normalized to average diogenite compo on the basis of ICP and XRF measurements and the experimental production rate eq of [7] and [8]. For the Antarctic samples with known terrestrial ages [9] correc were made for radioactive decay. In figure 1, the resulting 10Be and 26Al production rates are plotted against the 22Ne/21Ne ratios, which were measured on the same The solid lines represent the results of an exponential fitting procedure, from two samples were excluded: EET83246 because of SCR-produced 26Al and LEW88008 be of an anomalously low 26Al/10Be ratio, which is not yet understood. Figure 1 illustrates that the 10Be and 26Al production rates are similarly affect shielding conditions: both 10Be and 26Al decrease about 30 - 40% when going from objects with low 22Ne/21Ne ratios (<1.10) to small objects with high 22Ne/21Ne r (>1.25). Recently

  20. Distribution and chemical fate of 36Cl-chlorine dioxide gas during the fumigation of tomatoes and cantaloupe

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The distribution and chemical fate of 36Cl-ClO2 gas subsequent to fumigation of tomatoes or cantaloupe was investigated as was major factors that affect the formation of chloroxyanion byproducts. Approximately 22% of the generated 36Cl-ClO2 was present on fumigated tomatoes after a 2-hour exposure t...

  1. Measurement of cosmogenic /sup 36/Cl/Cl in young volcanic rocks: An application of accelerator mass spectrometry in geochronology

    SciTech Connect

    Leavy, B.D.; Phillips, F.M.; Elmore, D.; Kubik, P.W.

    1987-01-01

    We have measured /sup 36/Cl/Cl ratios in a number of young volcanic rocks in order to test the feasibility of using /sup 36/Cl buildup as a geochronometer for materials less than about 700,000 years old. All of the analyzed rocks have been dated independently using K-Ar or other radiometric dating methods and have exposure histories that are known or can be reasonably assumed. Measured /sup 36/Cl/Cl ratios in these rocks are in good agreement with the calculated in-situ /sup 36/Cl buildup curve. These analyses indicate that AMS measurement of /sup 36/Cl buildup in young rocks is a potentially powerful new method for dating materials that had previously been undatable, and as such will have broad applications in volcanology, tectonics, geophysics, and Quaternary research.

  2. Human calcium metabolism including bone resorption measured with {sup 41}Ca tracer

    SciTech Connect

    Freeman, S.P.H.T.; King, J.C.; Vieira, N.E.; Woodhouse, L.R.; Yergey, A.L.

    1996-08-01

    Accelerator mass spectrometry is so sensitive to small quantities of {sup 41}Ca that it might be used as a tracer in the study of human calcium kinetics to generate unique kinds of data. In contrast with the use of other Ca isotopic tracers, {sup 41}Ca tracer can be so administered that the tracer movements between the various body pools achieve a quasi steady state. Resorbing bone may thus be directly measured. We have tested such a protocol against a conventional stable isotope experiment with good agreement.

  3. 36Cl: A tracer in groundwater in the aquia formation of Southern Maryland

    USGS Publications Warehouse

    Purdy, C.B.; Mignerey, A.C.; Helz, G.R.; Drummond, D.D.; Kubik, P.W.; Elmore, D.; Hemmick, T.

    1987-01-01

    The Aquia Formation (Paleocene) of Southern Maryland, a marine unit consisting predominantly of quartz sands, but containing 20-40% glauconite, represents one of the many productive, heavily pumped aquifers of the Southeastern Coastal Plain. An unusually high 36Cl activity ( ~ 15 ?? modem water) measured in an outcrop sample is interpreted as a result of the bomb pulse input. About 25 km downdip from the recharge area, a minimum in total chloride concentration occurs. This minimum is thought to correlate with the latest low-stand of sea-level, and thus to provide time information which is in general agreement with ages calculated from hydrodynamic data. However, significant increases in the 36Cl concentrations are observed along the flow path which may be due to ion filtration or to leakage of modem, bomb-contaminated water into the Aquia aquifer. ?? 1987.

  4. Long-term measurements of 36Cl to investigate potential solar influence on the decay rate

    NASA Astrophysics Data System (ADS)

    Kossert, Karsten; Nähle, Ole J.

    2014-03-01

    Recently, Jenkins et al. [6] reported on fluctuations in the detected decay events of 36Cl which were measured with a Geiger-Müller counter. Experimental data of 32Si measured by means of an end-window gas-flow proportional counter at the Brookhaven National Laboratory show similar periodicity, albeit a different amplitude. Jenkins et al. interpret the fluctuations as evidence of solar influence on the decay rates of beta-decaying radionuclides.

  5. Calcium Isolation from Large-Volume Human Urine Samples for 41Ca Analysis by Accelerator Mass Spectrometry

    PubMed Central

    Miller, James J; Hui, Susanta K; Jackson, George S; Clark, Sara P; Einstein, Jane; Weaver, Connie M; Bhattacharyya, Maryka H

    2013-01-01

    Calcium oxalate precipitation is the first step in preparation of biological samples for 41Ca analysis by accelerator mass spectrometry. A simplified protocol for large-volume human urine samples was characterized, with statistically significant increases in ion current and decreases in interference. This large-volume assay minimizes cost and effort and maximizes time after 41Ca administration during which human samples, collected over a lifetime, provide 41Ca:Ca ratios that are significantly above background. PMID:23672965

  6. 36Cl ages of deep saline groundwater in coastal sedimentary areas in Japan

    NASA Astrophysics Data System (ADS)

    Tosaki, Y.; Morikawa, N.; Kazahaya, K.; Yasuhara, M.; Takahashi, H.; Horiguchi, K.; Sato, T.; Takahashi, M.; Inamura, A.

    2015-12-01

    Climate-induced sea-level fluctuations can have impacts on groundwater flow regimes, especially in coastal areas. A sea level decline leads to a seaward movement of the discharge area of regional groundwater flow system, accompanying increased hydraulic heads in aquifers that enhances deeper groundwater flow. It also brings drastic changes in shorelines and associated topography of coastal areas, which potentially affect groundwater flow regimes. Therefore, an assessment of the influence of sea-level change on groundwater system is especially important. In this study, we focus on several sedimentary basins in Japan, including the Ishikari Plain, the Tsugaru Plain, and the Kanto Plain. Saline groundwater samples were collected from deep boreholes located over the plains, and analyzed for 36Cl/Cl ratios. Several rock samples taken from each area were measured for whole-rock chemical compositions to determine the secular equilibrium 36Cl/Cl ratios in deep aquifers. The obtained 36Cl ages are generally greater than 100 kyr, and tend to become older in inland areas. These age distribution patterns for each area are compared with the locations of past shorelines. The results may show some factors, including topography and geology, which may control the influence of sea-level change on groundwater systems in coastal sedimentary areas. Acknowledgement: Main part of this research project has been conducted as the regulatory supporting research funded by the Secretariat of the Nuclear Regulation Authority, Japan.

  7. Cosmogenic {sup 36}Cl accumulation in unstable landforms 1. Effects of the thermal neutron distribution

    SciTech Connect

    Liu, B.; Phillips, F.M.; Stone, W.D.; Fabryka-Martin, J.T.; Fowler, M.M.

    1994-11-01

    Cosmogenic nuclides produced in situ within minerals at the surface of the Earth are proving to be an effective means of assessing geomorphic histories. The use of multiple cosmogenic nuclides permits both exposure times and erosion rates to be determined. However, if two nuclides are produced only by spallation reactions, the systematic differences in their accumulation rates depend only on the differences in their production rates and half-lives. The relatively small differences that result require a high degree of analytical precision to yield useful results. In contrast to other spallogenic nuclides, {sup 36}Cl is also produced by low-energy neutron, absorption, which creates a different pattern of production as a function of depth. We have measured the thermal flux with depth in a concrete block using {sup 3}He-filled neutron detectors. The measured thermal neutron profile agrees well with predictions from a simple diffusion-based thermal neutron distribution model. Calculations of {sup 36}Cl production using the model suggest that the use of {sup 36}Cl along with a purely spallogenic nuclide to determine erosion rates and exposure times should be less sensitive to analytical error than are determinations from two purely spallogenic nuclides. 31 refs., 7 figs., 3 tabs.

  8. Some possible evolutionary scenarios suggested by 36Cl measurements in Guarani aquifer groundwaters.

    PubMed

    Cresswell, R G; Bonotto, D M

    2008-08-01

    The Guarani aquifer underlies 1.2 M km2 in the Paraná sedimentary basin of South America and is an important source of water for industry, agriculture, and domestic supplies. To determine the sustainability of this aquifer we need to understand the dynamics of the groundwater system. This paper describes the first 36Cl measurements on aquifer groundwaters and some measurements on South American rainwaters, thought to be indicative of the recharge water. The results are compared to previous work in the region, including other radioisotope analyses. A simple model is developed, incorporating radioactive decay, allowing scenarios to be developed for mixing different waters at different mixing rates. Thus, mixing scenarios consistent with other hydrogeological and hydrogeochemical data could be assessed. A model that mixes fresh recharging waters with formational waters, that contain elevated chloride levels, but low (in situ) 36Cl levels, can explain most of the results presented here. The expectation that rainwater samples would provide a good end-member for modelling recharge proved problematic, however. As a consequence, it is suggested that either: the recharge waters are not sourced from the same locations as the rains; that the current rainfall and fallout conditions were significantly different in the past; or that the low levels of chloride in rainfall may have allowed some contamination of the samples by old (36Cl-free) chloride during the recharge process.

  9. Cosmogenic 36Cl ages of Quaternary basalt flows in the Mojave Desert, California, USA

    NASA Astrophysics Data System (ADS)

    Phillips, Fred M.

    2003-07-01

    Basalt flows provide excellent opportunities for calibration and intercomparison of Quaternary dating methods, remote sensing methods, and rates of geomorphic processes. The immediate motivation for this study was to provide chronology for a blind test of the utility of rock varnish microstratigraphy as an indicator of the age of flow emplacement. Five basaltic eruptive centers in the Mojave Desert of California were sampled for cosmogenic 36Cl analysis. Multiple samples were taken from most centers and, with one exception, produced good agreement. Assuming a surficial erosion rate of 1 mm/kyr -1, the flows yielded the following ages: Amboy Crater, 79±5 ka; Pisgah Crater, 22.5±1.3 ka; Cima field, I-Cone, 27±1.3 ka; Cima field, A-Cone, 21±1.6 ka and 11.5±1.5 ka; Cima field, flow of unidentified origin, 46±2 ka. The ages from the Cima I and A cones are in good agreement with previous cosmogenic 3He dating. Ages from the three previously undated flows are significantly older than previous estimates based on flow appearance. Tanzhou Liu performed varnish microstratigraphic analysis on samples collected from the same sites. His results were submitted for publication without knowledge of the 36Cl ages. His age estimates agree well with the 36Cl ages for the three previously undated flows, strongly supporting the validity of varnish microstratigraphy as a chronological correlation tool.

  10. 41Ca ultratrace determination with isotopic selectivity > 10(12) by diode-laser-based RIMS.

    PubMed

    Müller, P; Bushaw, B A; Blaum, K; Diel, S; Geppert, C; Nähler, A; Trautmann, N; Nörtershäuser, W; Wendt, K

    2001-07-01

    41Ca ultratrace determination by diode-laser-based resonance ionization mass spectrometry with extremely high isotopic selectivity is presented. Application to environmental dosimetry of nuclear reactor components, to cosmochemical investigations of production cross sections, and biomedical isotope-tracer studies of human calcium kinetics are discussed. Future investigations are possible use in 41Ca-radiodating. Depending on the application, 41Ca isotopic abundances in the range of 10(-9) to 10(-15) relative to the dominant stable isotope 40Ca must be determined. Either double- or triple-resonance optical excitation with narrow-band extended cavity diode lasers and subsequent non-resonant photoionization of calcium in a collimated atomic beam were used. The resulting photoions are detected with a quadrupole mass spectrometer optimized for background reduction and neighboring mass suppression. Applying the full triple-resonance scheme provides a selectivity of approximately 5 x 10(12) in the suppression of neighboring isotopes and > 10(8) for isobars, together with an overall detection efficiency of approximately 5 x 10(-5). Measurements on a variety of sample types are discussed; the accuracy and reproducibility of the resulting 41Ca/40Ca isotope ratios was better than 5%.

  11. Cosmogenic 36Cl in karst waters from Bunker Cave North Western Germany - A tool to derive local evapotranspiration?

    NASA Astrophysics Data System (ADS)

    Münsterer, C.; Fohlmeister, J.; Christl, M.; Schröder-Ritzrau, A.; Alfimov, V.; Ivy-Ochs, S.; Wackerbarth, A.; Mangini, A.

    2012-06-01

    Monthly rain and drip waters were collected over a period of 10 months at Bunker Cave, Germany. The concentration of 36Cl and the 36Cl/Cl-ratios were determined by accelerator mass spectrometry (AMS), while stable (35+37)Cl concentrations were measured with both, ion chromatography (IC) and AMS. The measured 36Cl-fluxes of (0.97 ± 0.57) × 104 atoms cm-2 month-1 (0.97 atoms m-2 month-1) in precipitation were on average twice as high as the global mean atmospheric production rate. This observation is consistent with the local fallout pattern, which is characterized by a maximum at mid-latitudes. The stable chloride concentration in drip waters (ranging from 13.2 to 20.9 mg/l) and the 36Cl-concentrations (ranging from 16.9 × 106 to 35.3 × 106 atoms/l) are a factor of 7 and 10 above the values expected from empirical evapotranspiration formulas and the rain water concentrations, respectively. Most likely the additional stable Cl is due to human impact from a nearby urban conglomeration. The large 36Cl-enrichment is attributed to the local evapotranspiration effect, which appears to be higher than the calculated values and to additional bomb-derived 36Cl from nuclear weapons tests in the 1950s and 60s stored in the soil above the cave. In the densely vegetated soil above Bunker Cave, 36Cl seems not to behave as a completely conservative tracer. The bomb derived 36Cl might be retained in the soil due to uptake by minerals and organic material and is still being released now. Based on our data, the residence time of 36Cl in the soil is estimated to be about 75-85 years.

  12. Final report-98-ERI-003 identification of population with lifetime 41Ca-labeled skeletons

    SciTech Connect

    Freeman, S P

    1999-02-25

    In 1997 we first postulated the existence of a special human population that had had their skeletons inadvertently isotopically adulterated in the past. We theorized that the population, and the necessary LLNL accelerator mass spectrometer (AMS) measurement technology, would prove a significant resource in the fight to combat osteoporosis. This LDRD project was to establish such. The project was significantly successful in its initial year, but was not renewed for another and the research is now ended at LLNL. We proposed a three-year program to (1) confirm the magnitude and extent of historical 41 Ca dosing, (2) exactly characterize the long-term 41 Ca signal by comparing it with conventional measurements of skeletal health, and (3) demonstrate the utility of the historically labeled population in evaluating an actual potential therapy for osteoporosis. However, rather than investigate historical records to learn the identity of those inadvertently dosed, find them, and if possible enroll them into a new protocol, this project was to be particularly efficient by making use of a multiyear archive of samples from original, inadvertent 41 Ca-dosing experiments at Creighton University in Omaha, Nebraska. Because the subjects had been dosed in conventional studies of calcium kinetics, much important correlating historical data would also be available for comparison. Measurements of contemporary urine samples specifically provided for this project by selected identified subjects would follow. We discovered a second archive at the University of Texas Southwestern Medical Center. This is potentially a better source of material as the samples were generated in numerous historical evaluations of actual osteoporosis therapies in which 41 Ca-impure radiotracers were used. The therapies might now powerfully be retrospectively evaluated, both to contribute to our understanding of the therapies and to highlight the potential of the use of 41 Ca tracer and LLNL measurement.

  13. Study on 41Ca-AMS for diagnosis and assessment of cancer bone metastasis in rats

    NASA Astrophysics Data System (ADS)

    Shen, Hongtao; Pang, Fangfang; Jiang, Shan; He, Ming; Dong, Kejun; Dou, Liang; Pang, Yijun; Yang, Xianlin; Ruan, Xiangdong; Liu, Manjun; Xia, Chunbo

    2015-10-01

    The annual incidence of new cancer patients in China is about 2 million, 30-40% of which will end up with bone metastasis. Profound study on the preclinical model and early diagnosis of cancer bone metastasis in rats are very significant for the drug development, better understanding and treatment of bone metastases. In order to monitor the process of bone metabolism and early detection of bone metastasis of cancer cells, a technique of 41Ca isotope tracer combined with AMS has been developed and applied in the study on the bone metastasis of cancer cells by rat model. In this work, 3-month-old female Sprague-Dawley (SD) rats were randomly divided into different groups, and tumor cells injected respectively into the tail vein, femoral artery, femoral cavity and the thigh muscle to establish the rat models for bone metastases. The most appropriate model, i.e., the thigh muscle group, was finally adopted in our real metastases experiment. Each rat in this group was intramuscularly (i.m.) injected with 250 μl CaCl2 solution (containing 1.4 mg Ca and 5nCi 41Ca). About 40 days later, the rat mammary gland carcinoma cells (Walker 256) were injected into these rats following the established protocol. After bone metastasis, medicine interventions were performed. The sequential urine and blood samples were collected and analyzed for 41Ca (by AMS) and N-terminal telopeptide (Ntx), respectively. Bone Mineral Density (BMD) values in the femur and the tibia were measured by CT scan. The results of 41Ca/Ca in longitudinal urinary samples can sensitively reveal the skeletal perturbations caused by bone metastasis of rats, suggests that 41Ca might be similarly developed for human use and improve clinical management through the assessment of the curative effect and non-invasive detection of the earliest stages of cancer growth in bone.

  14. Determination of paleoseismic activity over a large time-scale: Fault scarp dating with 36Cl

    NASA Astrophysics Data System (ADS)

    Mozafari Amiri, Nasim; Tikhomirov, Dmitry; Sümer, Ökmen; Özkaymak, Çaǧlar; Uzel, Bora; Ivy-Ochs, Susan; Vockenhuber, Christof; Sözbilir, Hasan; Akçar, Naki

    2016-04-01

    Bedrock fault scarps are the most direct evidence of past earthquakes to reconstruct seismic activity in a large time-scale using cosmogenic 36Cl dating if built in carbonates. For this method, a surface along the fault scarp with a minimum amount of erosion is required to be chosen as an ideal target point. The section of the fault selected for sampling should cover at least two meters of the fault surface from the lower part of the scarp, where intersects with colluvium wedge. Ideally, sampling should be performed on a continuous strip along the direction of the fault slip direction. First, samples of 10 cm high and 15 cm wide are marked on the fault surface. Then, they are collected using cutters, hammer and chisel in a thickness of 3 cm. The main geometrical factors of scarp dip, scarp height, top surface dip and colluvium dip are also measured. Topographic shielding in the sampling spot is important to be estimated as well. Moreover, density of the fault scarp and colluvium are calculated. The physical and chemical preparations are carried in laboratory for AMS and chemical analysis of the samples. A Matlab® code is used for modelling of seismically active periods based on increasing production rate of 36Cl following each rupture, when a buried section of a fault is exposed. Therefore, by measuring the amount of cosmogenic 36Cl versus height, the timing of major ruptures and their offsets are determined. In our study, Manastır, Mugırtepe and Rahmiye faults in Gediz graben, Priene-Sazlı, Kalafat and Yavansu faults in Büyük Menderes graben and Ören fault in Gökava half-graben have been examined in the seismically active region of Western Turkey. Our results reconstruct at least five periods of high seismic activity during the Holocene time, three of which reveal seismic ruptures beyond the historical pre-existing data.

  15. FINDING TRACERS FOR SUPERNOVA PRODUCED {sup 26}Al

    SciTech Connect

    Young, Patrick A.; Ellinger, Carola I.; Arnett, David; Fryer, Chris L.; Rockefeller, Gabriel

    2009-07-10

    We consider the cospatial production of elements in supernova explosions to find observationally detectable proxies for enhancement of {sup 26}Al in supernova ejecta and stellar systems. Using four progenitors, we explore a range of one-dimensional explosions at different energies and an asymmetric three-dimensional explosion. We find that the most reliable indicator of the presence of {sup 26}Al in unmixed ejecta is a very low S/Si ratio ({approx}0.05). Production of N in O/S/Si-rich regions is also indicative. The biologically important element P is produced at its highest abundance in the same regions. Proxies should be detectable in supernova ejecta with high spatial resolution multiwavelength observations, but the small absolute abundance of material injected into a proto-planetary disk makes detection unlikely in existing or forming stellar/planetary systems.

  16. Depth dependence of soil carbonate accumulation based on cosmogenic [sup 36]Cl dating

    SciTech Connect

    Liu, B.; Phillips, F.M. ); Elmore, D.; Sharma, P. )

    1994-12-01

    Indurated pedogenic carbonate layers (calcretes) are common in soils on stable surfaces in arid to semiarid climates. The morphology and composition of calcretes provide important information on the geomorphic and climatic histories of the regions where they are formed, but they have proved difficult to date with conventional radiometric methods. We report cosmogenic [sup 36]Cl-buildup ages from three fractions (leachable Cl, carbonate, silicate) of a calcrete from the surface of an alluvial slope below the Ajo Mountains in southern Arizona. All three fractions give reasonably concordant ages, ranging from 700 ka at the base of the calcrete horizon to 200 ka at its top. These ages are in good agreement both with estimates of age based on correlation with similar, independently dated, soils in the region and with [sup 36]Cl-buildup ages on surficial boulders. These results support the ideas that calcretes accumulate upward with time and that water movement through the carbonate matrix is very limited after induration. 19 refs., 2 figs., 1 tab.

  17. 36Cl/Cl ratios in geothermal systems: preliminary measurements from the Coso Field

    SciTech Connect

    Nimz, G.J.; Moore, J.N.; Kasameyer, P.W.

    1997-07-01

    The {sub 36}Cl/Cl isotopic composition of chlorine in geothermal systems can be a useful diagnostic tool in characterizing hydrologic structure, in determining the origins and age of waters within the systems, and in differentiating the sources of chlorine (and other solutes) in the thermal waters. The {sub 36}Cl/Cl values for several geothermal water samples and reservoir host rock samples from the Coso, California geothermal field have been measured for these purposes. The results indicate that most of the chlorine is not derived from the dominant granitoid that host the geothermal system. If the chlorine was originally input into the Coso subsurface through meteoric recharge, that input occurred at least 1-1.25 million years ago. The results suggest that the thermal waters could be connate waters derived from sedimentary formations, presumably underlying and adjacent top the granitic rocks, which have recently migrated into the host rocks. Alternatively, most of the chlorine but not the water, may have recently input into the system from magmatic sources. In either case, the results indicate that most of the chlorine in the thermal waters has existed within the granitoid host rocks for no more than about 100,00-200,00 years. this residence time for the chlorine is similar to residence times suggested by other researchers for chlorine in deep groundwaters of the Mono Basin north of the Coso field.

  18. 36Cl measurements in Hiroshima granite samples as part of an international intercomparison study. Results from the Munich group.

    PubMed

    Huber, T; Rühm, W; Hoshi, M; Egbert, S D; Nolte, E

    2003-04-01

    Within the effort to resolve the so-called Hiroshima neutron discrepancy, an international intercomparison study has been carried out on granite samples from Hiroshima, with participating institutions from Japan, the US, and Germany. (36)Cl and (152)Eu produced in these samples by thermal neutrons from the A-bomb explosion were assessed independently by means of different techniques. At the Maier-Leibnitz-Laboratory near Munich, Germany, (36)Cl concentrations were measured by accelerator mass spectrometry. Measured (36)Cl/Cl ratios ranged from 1,670 x 10(-13) (at a distance of 146 m from the hypocenter) to 2.2 x 10(-13) (at a distance of 1,163 m from the hypocenter). One granite sample not exposed to A-bomb neutrons was measured as a control, and a (36)Cl/Cl ratio of 2.6 x 10(-13) was obtained. On average, our experimental results are 20-30% lower than those provided by model calculations based on the dosimetry system DS86. The results presented here do not support previous assessments of (36)Cl, (60)Co, and (152)Eu which had suggested much larger thermal neutron fluences than those calculated on the basis of DS86 for distances from the hypocenter of more than 1,000 m.

  19. Short lived 36Cl and its decay products 36Ar and 36S in the early solar system

    NASA Astrophysics Data System (ADS)

    Turner, G.; Crowther, S. A.; Burgess, R.; Gilmour, J. D.; Kelley, S. P.; Wasserburg, G. J.

    2013-12-01

    Variable excesses of 36S have previously been reported in sodalite in the Allende and Ningqiang meteorites and used to infer the presence of 36Cl in the early solar system. Until now no unambiguous evidence of the major decay product, 36Ar (98%), has been found. Using low fluence fast neutron activation we have measured small amounts of 36Ar in the Allende sodalite Pink Angel, corresponding to 36Cl/35Cl = (1.9 ± 0.5) × 10-8. This is a factor of 200 lower than the highest value inferred from 36S excesses in sodalite. High resolution I-Xe analyses confirm that the sodalite formed between 4561 and 4558 Ma ago. The core of Pink Angel sodalite yielded a precise formation age of 4559.4 ± 0.6 Ma. Deposition of sodalite containing live 36Cl, seven million years or so after the formation of the CAI, appears to require a local production mechanism involving intense neutron irradiation within the solar nebula. The constraint imposed by the near absence of neutron induced 128Xe is most easily satisfied if the 36Cl were produced in a fluid precursor of the sodalite. The low level of 36Ar could be accounted for as a result of residual in-situ36Cl decay, up to 1-2 Ma after formation of the sodalite, and/or later diffusive loss, in line with the low activation energy for Ar diffusion in sodalite.

  20. (26)Al investigations at the AMS-laboratory in Lund.

    PubMed

    Faarinen, M; Magnusson, C E; Hellborg, R; Mattsson, S; Kiisk, M; Persson, P; Schütz, A; Skog, G; Stenström, K

    2001-11-01

    At the accelerator mass spectrometry (AMS) laboratory in Lund, a facility for (26)Al analysis is under development. The sensitivity is expected to be several orders of magnitude higher than with standard mass spectrometry. The planned biomedical program includes studies of aluminium uptake, distribution and retention in man. The initial work has been concentrated on the construction and testing of a new dedicated injector for the accelerator and on the preparation of biological samples for aluminium analysis. The current quality of the facility is presented and the first experimental results reported. PMID:11709214

  1. Improving AMS Detection of the Biomedical Radiotracer 41Ca with Segmented Radio-Frequency Quadrupoles

    NASA Astrophysics Data System (ADS)

    Alary, Jean-Francois; Javahery, Gholamreza; Kieser, William E.; Litherland, Albert E.; Cousins, Lisa M.

    41Ca is an important biomedical radiotracer finding many applications in biological, nutritional and medical studies. The detection of 41Ca by AMS is however limited by an important background signal of 41K originating from biological samples and from contaminated cesium in the source. An approach consisting of using PbF2-assisted in-source fluorination in combination with an Isobar Separator for Anions (ISA), a device incorporating a low energy radio frequency quadrupole (RFQ) gas cell, promises to push down the limit of detection of 41Ca attainable on small (<3 MV) accelerator mass spectrometry (AMS) systems by several orders of magnitude. Such on-line reduction of 41K should also result in a simplification of biological sample preparation and less concern about variable 41K contamination of the cesium beam. The selective collision-induced fragmentation of KF3- versus CaF3-, occurring in the gas cell of an ISA equipped with a double segment RFQ, have been reported earlier1), leading to K being suppressed by a factor of 1e4 over Ca. We present here the future configuration of the ISA, redesigned using multi-segmented RFQ to enhance further this effect and improve transmission through the gas cell. A segmented RFQ is an appropriate tool to finely control ion energy down to the few eV's separating the fragmentation energies of the two fluoride species. This pre-commercial ISA destined to be used at the newly established A. E. Lalonde AMS laboratory at University of Ottawa (Canada) will be presented. Some practicalities of integrating a low energy RFQ-based device in a high energy AMS system will also be discussed.

  2. Inventory of site-derived {sup 36}Cl in the Snake River plain aquifier, Idaho National Engineering Laboratory, Idaho

    SciTech Connect

    Beasley, T.M.

    1995-02-01

    Radioactive waste management practices at the U.S. Department of Energy`s Idaho National Engineering Laboratory (INEL) in Idaho have introduced {sup 36}Cl (T{sub 1/2} = 301,000 yr) into the Snake River Plain aquifer underlying the site. The {sup 36}Cl is believed to originate from neutron activation of stable {sup 35}Cl in nuclear fuels (principally) and in reactor cooling/process water. Wastewater releases of {sup 3}H at the INEL have been documented by the site operators for the period 1952 to 1988. During this time, approximately 1.2 PBq of {sup 3}H (30,000 Ci) were introduced to the subsurface through disposal wells and seepage ponds. By sampling a number of monitoring and production wells downgradient from points of introduction, {sup 3}H movement and dispersion in the groundwater have been documented by the U.S. Geological Survey. The present report uses these historical {sup 3}H release and monitoring data to choose hydrologic parameters (matrix porosity and plume penetration depth) that produce concordance between the {sup 3}H release estimates and the inventory calculated from measurements of {sup 3}H in the subsurface. These parameters are then applied to {sup 36}Cl isopleths to generate an estimated {sup 36}Cl inventory in the subsurface. Using assumptions about irradiation times, neutron fluxes, and total fuel processed, as little as 23 g of stable chloride impurity in fuel elements would be adequate to produce the amount of {sup 36}Cl estimated to be in the groundwaters underlying the site. The highest atom concentration of {sup 36}Cl measured onsite (222x10{sup 10} atoms 1{sup -1}) corresponds to an activity level of {approximately}4 pCi 1{sup -1} and represents 0.2 percent of the U.S. Environmental Protection Agency`s (EPA) drinking water standard for this radionuclide (2000 pCi 1{sup -1}).

  3. Age and geomorphic history of Meteor Crater, Arizona, from cosmogenic 36Cl and 14C in rock varnish

    USGS Publications Warehouse

    Phillips, F.M.; Zreda, M.G.; Smith, S.S.; Elmore, D.; Kubik, P.W.; Dorn, R.I.; Roddy, D.J.

    1991-01-01

    Using cosmogenic 36Cl buildup and rock varnish radiocarbon, we have measured the exposure age of rock surfaces at Meteor Crater, Arizona. Our 36Cl measurements on four dolomite boulders ejected from the crater by the impact yield a mean age of 49.7 ?? 0.85 ka, which is in excellent agreement with an average age of 49 ?? 3 ka obtained from thermoluminescence studies on shock-metamorphosed dolomite and quartz. These ages are supported by undetectably low 14C in the oldest rock varnish sample. ?? 1991.

  4. Precise and direct determination of the half-life of 41Ca

    NASA Astrophysics Data System (ADS)

    Jörg, Gerhard; Amelin, Yuri; Kossert, Karsten; Lierse v. Gostomski, Christoph

    2012-07-01

    Calcium-41 plays an important role in the long-term evaluation of the safety of final repositories for nuclear waste and is used to study the fine-scale chronology of the formation of the Solar System. Both applications are hindered by insufficient precision and poor consistency of previous determinations of the half-life. This work reports a half-life for 41Ca of (9.94 ± 0.15) × 104 years, which was determined with a combination of methods, chosen to provide the best possible precision. The activity was measured by liquid scintillation counting (LSC) exploiting the triple-to-double coincidence ratio method (TDCR); the absolute isotopic composition was determined by thermal ionization mass spectrometry (TIMS) and isotope dilution. Enhanced precision and accuracy of the 41Ca half-life will allow the improvement of safety analyses for final deposit sites of nuclear waste and of dating first solids, and better constrain the stellar environment of the formation of the Solar System.

  5. Biological sample preparation and {sup 41}Ca AMS measurement at LLNL

    SciTech Connect

    Freeman, S.P.H.T.; Southon, J.R.; Bench, G.S.; McAninch, J.E.; Serfass, R.E.; Fang, Y.; King, J.C.; Woodhouse, L.R.

    1994-10-10

    Calcium metabolism in biology may be better understood by the use of {sup 41}Ca labels, although detection by accelerator mass spectrometry (AMS) is required. Methodologies for preparation of urine samples and subsequent AMS measurement were investigated. Novel attempts at preparing CaH{sub 2} were unsuccessful, but CaF{sub 2} of sufficient purity could be produced by precipitation of calcium from urine as oxalate, followed by separation of calcium by cation exchange chromatography and washing the CaF{sub 2} precipitate. The presence of some remaining impurities could be compensated for by selecting the appropriate accelerated ion charge state for AMS. The use of projectile x rays for isobar discrimination was explored as an alternative to the conventional dE/dx device.

  6. (41)Ca in tooth enamel. Part I: a biological signature of neutron exposure in atomic bomb survivors.

    PubMed

    Wallner, A; Rühm, W; Rugel, G; Nakamura, N; Arazi, A; Faestermann, T; Knie, K; Maier, H J; Korschinek, G

    2010-08-01

    The detection of (41)Ca atoms in tooth enamel using accelerator mass spectrometry is suggested as a method capable of reconstructing thermal neutron exposures from atomic bomb survivors in Hiroshima and Nagasaki. In general, (41)Ca atoms are produced via thermal neutron capture by stable (40)Ca. Thus any (41)Ca atoms present in the tooth enamel of the survivors would be due to neutron exposure from both natural sources and radiation from the bomb. Tooth samples from five survivors in a control group with negligible neutron exposure were used to investigate the natural (41)Ca content in tooth enamel, and 16 tooth samples from 13 survivors were used to estimate bomb-related neutron exposure. The results showed that the mean (41)Ca/Ca isotope ratio was (0.17 +/- 0.05) x 10(-14) in the control samples and increased to 2 x 10(-14) for survivors who were proximally exposed to the bomb. The (41)Ca/Ca ratios showed an inverse correlation with distance from the hypocenter at the time of the bombing, similar to values that have been derived from theoretical free-in-air thermal-neutron transport calculations. Given that gamma-ray doses were determined earlier for the same tooth samples by means of electron spin resonance (ESR, or electron paramagnetic resonance, EPR), these results can serve to validate neutron exposures that were calculated individually for the survivors but that had to incorporate a number of assumptions (e.g. shielding conditions for the survivors).

  7. (41)Ca in tooth enamel. Part I: a biological signature of neutron exposure in atomic bomb survivors.

    PubMed

    Wallner, A; Rühm, W; Rugel, G; Nakamura, N; Arazi, A; Faestermann, T; Knie, K; Maier, H J; Korschinek, G

    2010-08-01

    The detection of (41)Ca atoms in tooth enamel using accelerator mass spectrometry is suggested as a method capable of reconstructing thermal neutron exposures from atomic bomb survivors in Hiroshima and Nagasaki. In general, (41)Ca atoms are produced via thermal neutron capture by stable (40)Ca. Thus any (41)Ca atoms present in the tooth enamel of the survivors would be due to neutron exposure from both natural sources and radiation from the bomb. Tooth samples from five survivors in a control group with negligible neutron exposure were used to investigate the natural (41)Ca content in tooth enamel, and 16 tooth samples from 13 survivors were used to estimate bomb-related neutron exposure. The results showed that the mean (41)Ca/Ca isotope ratio was (0.17 +/- 0.05) x 10(-14) in the control samples and increased to 2 x 10(-14) for survivors who were proximally exposed to the bomb. The (41)Ca/Ca ratios showed an inverse correlation with distance from the hypocenter at the time of the bombing, similar to values that have been derived from theoretical free-in-air thermal-neutron transport calculations. Given that gamma-ray doses were determined earlier for the same tooth samples by means of electron spin resonance (ESR, or electron paramagnetic resonance, EPR), these results can serve to validate neutron exposures that were calculated individually for the survivors but that had to incorporate a number of assumptions (e.g. shielding conditions for the survivors). PMID:20681780

  8. Using 36Cl data to quantify the paleorecharge in arid region. Example of the North Western Saharan Aquifer System.

    NASA Astrophysics Data System (ADS)

    Oriane Petersen, Jade; Deschamps, Pierre; Gonçalvès, Julio; Hamelin, Bruno; Michelot, Jean-Luc; Guendouz, Abdelhamid; Zouari, Kamel

    2014-05-01

    A comprehensive understanding of large-scale systems such as multi-layer aquifers in sedimentary basins (e.g. North Western Saharan Aquifer System -NWSAS- or the Great Artesian Basin) requires to investigate the recharge history to Quaternary timescale. In fact, for such systems, the residence time of groundwater is often in the order of 100 000 years to 1 million years, the recharge occurring during past, intermittent humid periods paced by the quaternary climatic cycles. In this study, we propose to reconstruct the history of the recharge over the Continental Intercalaire (CI) aquifer, one of the two main aquifers of the NWSAS. It extends over 1 million km2, shared between Algeria, Tunisia and Libya. We focus on the main recharge area of the CI aquifer located in the Algerian Atlas Mountains. Existing chlorine-36 data (36Cl half-life: 301 ka) indicate that groundwater residence time in this system is around 1 million years. A set of modeling approaches is combined to model the theoretical 36Cl/Cl distribution within the aquifer as a function of different recharge scenarios. Seventeen 36Cl/Cl data from two distinct flowpaths provide temporal constraints on groundwater ages. A simple piston model is used to simulate the distribution of theoretical 36Cl along these flowlines as a function of the distance from the outcrop with respect to a recharge scenario. Simplified climatic scenarios are constructed considering humid periods only during interglacial cycles. This allows to define 9 recharge rates (Rh(i)) associated to last interglacials (from marine isotope stages MIS1 to MIS19). In addition, a constant recharge Rg was considered during glacial periods. For each recharge scenario, the recharge values are constrained by using a Markov Chain Monte Carlo (MCMC) inversion, which yields the best agreement between measured and modeled 36Cl/Cl. This MCMC probabilistic inversion approach allows identifying plausible sets of the 10 parameters (9 Rh(i) and Rg) involved in

  9. Effective determination of the long-lived nuclide 41Ca in nuclear reactor bioshield concretes: comparison of liquid scintillation counting and accelerator mass spectrometry.

    PubMed

    Warwick, P E; Croudace, I W; Hillegonds, D J

    2009-03-01

    The routine application of liquid scintillation counting to (41)Ca determination has been hindered by the absence of traceable calibration standards of known (41)Ca activity concentrations. The introduction of the new IRMM (41)Ca mass-spectrometric standards with sufficiently high (41)Ca activities for radiometric detection has partly overcome this although accurate measurement of stable Ca concentrations coupled with precise half-life data are still required to correct the certified (41)Ca:(40)Ca ratios to (41)Ca activity concentrations. In this study, (41)Ca efficiency versus quench curves have been produced using the IRMM standard, and their accuracy validated by comparison with theoretical calculations of (41)Ca efficiencies. Further verification of the technique was achieved through the analysis of (41)Ca in a reactor bioshield core that had been previously investigated for other radionuclide variations. Calcium-41 activity concentrations of up to 25 Bq/g were detected. Accelerator mass spectrometry (AMS) measurements of the same suite of samples showed a very good agreement, providing validation of the procedure. Calcium-41 activity concentrations declined exponentially with distance from the core of the nuclear reactor and correlated well with the predicted neutron flux.

  10. Evidence from cosmic-ray exposure dating based on 36Cl for the pre-Minoan caldera on Santorini, Greece

    NASA Astrophysics Data System (ADS)

    Athanassas, Constantin; Bourlès, Didier; Braucher, Regis; Druitt, Tim; Nomikou, Paraskevi; Léanni, Laetitia

    2016-04-01

    The physiography of Santorini prior to the Minoan (Late Bronze Age) eruption (17th century BCE) is of great archaeological interest, given the importance of Santorini as a commercial centre and port in the Minoan empire. However, the paleogeography of the pre-Minoan caldera has been a point of controversy: Heiken and McCoy (1984) advocated the existence, in the southern part of the present-day caldera, of a pre-existing caldera formed during the 172 ka Lower Pumice eruption, whereas Druitt and Francaviglia (1992), based on the presence of in situ plinian pumice from the Minoan eruption adhering to the modern cliff, conceived the pre-Minoan (22 ka) caldera as having occupied much of the northern basin of the present-day caldera. With the goal of settling the debate we performed cosmic ray exposure dating employing in situ-produced cosmogenic 36Cl to date different generations of caldera cliffs at Santorini, and hence to identify those cliffs predating the Minoan eruption. Our methodology involved the determination of the in situ-produced cosmogenic 36Cl in basaltic and andesitic rocks cropping out in the cliffs. The samples returned 36Cl CRE ages consistent with previously published field mapping of cliff populations based on geomorphological and stratigraphic arguments (Druitt and Francaviglia 1992), suggesting that much of the present cliff line of northern Santorini predated the Minoan eruption, or was superficially modified by landslips and rockfalls during that eruption. The 36Cl CRE ages enable us to better define the paleogeography of the pre-Minoan caldera. References [1] Druitt, T. H. and Francaviglia, V.1992. Caldera formation on Santorini and the physiography of the islands in the Late Bronze Age. Bulletin of Volcanology 54, 484-493. [2] Heiken G and McCoy F (1984) Caldera development during the Minoan eruption, Thira, Cyclades, Greece. Journal of Geophysical Research: 89 (B10), 8841-8862.

  11. Total radioactive residues and residues of [36Cl]chlorate in market size broilers.

    PubMed

    Smith, David J; Byrd, James A; Anderson, Robin C

    2007-07-11

    The oral administration of chlorate salts reduces the numbers of Gram-negative pathogens in gastrointestinal tracts of live food animals. Although the efficacy of chlorate salts has been demonstrated repeatedly, the technology cannot be introduced into commercial settings without first demonstrating that chlorate residues, and metabolites of chlorate remaining in edible tissues, represent a negligible risk to consumers. Typically, a first step in this risk assessment is to quantify the parent compound and to identify metabolites remaining in edible tissues of animals treated with the experimental compound. The objectives of this study were to determine the pathway(s) of chlorate metabolism in market broilers and to determine the magnitude of chlorate residues remaining in edible tissues. To this end, 12 broilers (6 weeks; 2.70+/-0.34 kg) were randomly assigned to three treatments of 7.4, 15.0, and 22.5 mM sodium [36Cl]chlorate dissolved in drinking water (n=4 broilers per treatment). Exposure to chlorate, dissolved in drinking water, occurred at 0 and 24 h (250 mL per exposure), feed was withdrawn at hour 38, water was removed at hour 48, and birds were slaughtered at hour 54 (16 h after feed removal and 8 h after water removal). The radioactivity was rapidly eliminated in excreta with 69-78% of the total administered radioactivity being excreted by slaughter. Total radioactive residues were proportional to dose in all edible tissues with chloride ion comprising greater than 98.5% of the radioactive residue for the tissue (9.4-97.8 ppm chlorate equivalents). Chlorate residues were typically greatest in the skin (0.33-0.82 ppm), gizzard (0.1-0.137 ppm), and dark muscle (0.05-0.14 ppm). Adipose, liver, and white muscle tissue contained chlorate concentrations from 0.03 to 0.13 ppm. In contrast, chlorate concentrations in excreta eliminated during the 6 h period prior to slaughter ranged from 53 to 71 ppm. Collectively, these data indicate that broilers rapidly

  12. Total radioactive residues and residues of [36Cl]chlorate in market size broilers.

    PubMed

    Smith, David J; Byrd, James A; Anderson, Robin C

    2007-07-11

    The oral administration of chlorate salts reduces the numbers of Gram-negative pathogens in gastrointestinal tracts of live food animals. Although the efficacy of chlorate salts has been demonstrated repeatedly, the technology cannot be introduced into commercial settings without first demonstrating that chlorate residues, and metabolites of chlorate remaining in edible tissues, represent a negligible risk to consumers. Typically, a first step in this risk assessment is to quantify the parent compound and to identify metabolites remaining in edible tissues of animals treated with the experimental compound. The objectives of this study were to determine the pathway(s) of chlorate metabolism in market broilers and to determine the magnitude of chlorate residues remaining in edible tissues. To this end, 12 broilers (6 weeks; 2.70+/-0.34 kg) were randomly assigned to three treatments of 7.4, 15.0, and 22.5 mM sodium [36Cl]chlorate dissolved in drinking water (n=4 broilers per treatment). Exposure to chlorate, dissolved in drinking water, occurred at 0 and 24 h (250 mL per exposure), feed was withdrawn at hour 38, water was removed at hour 48, and birds were slaughtered at hour 54 (16 h after feed removal and 8 h after water removal). The radioactivity was rapidly eliminated in excreta with 69-78% of the total administered radioactivity being excreted by slaughter. Total radioactive residues were proportional to dose in all edible tissues with chloride ion comprising greater than 98.5% of the radioactive residue for the tissue (9.4-97.8 ppm chlorate equivalents). Chlorate residues were typically greatest in the skin (0.33-0.82 ppm), gizzard (0.1-0.137 ppm), and dark muscle (0.05-0.14 ppm). Adipose, liver, and white muscle tissue contained chlorate concentrations from 0.03 to 0.13 ppm. In contrast, chlorate concentrations in excreta eliminated during the 6 h period prior to slaughter ranged from 53 to 71 ppm. Collectively, these data indicate that broilers rapidly

  13. Heterogeneous Distribution of 26Al at the Birth of the Solar System

    NASA Astrophysics Data System (ADS)

    Makide, Kentaro; Nagashima, Kazuhide; Krot, Alexander N.; Huss, Gary R.; Ciesla, Fred J.; Hellebrand, Eric; Gaidos, Eric; Yang, Le

    2011-06-01

    It is believed that 26Al, a short-lived (t 1/2 = 0.73 Ma) and now extinct radionuclide, was uniformly distributed in the nascent solar system (SS) with the initial 26Al/27Al ratio of ~5.2 × 10-5, suggesting an external, stellar origin rather than local, solar source. However, the stellar source of 26Al and the manner in which it was injected into the SS remain controversial: the 26Al could have been produced by an asymptotic giant branch star, a supernova, or a Wolf-Rayet star and injected either into the protosolar molecular cloud, protosolar cloud core, or protoplanetary disk. Corundum (Al2O3) is predicted to be the first condensate from a cooling gas of solar composition. Here we show that micron-sized corundum condensates from 16O-rich (Δ17O ~ -25‰) gas of solar composition recorded heterogeneous distribution of 26Al at the birth of the SS: the inferred initial 26Al/27Al ratio ranges from ~6.5×10-5 to <2×10-6 52% of corundum grains measured are 26Al-poor. Abundant 26Al-poor, 16O-rich refractory objects include grossite- and hibonite-rich calcium-aluminum-rich inclusions (CAIs) in CH (high metal abundance and high iron concentration) chondrites, platy hibonite crystals in CM (Mighei-like) chondrites, and CAIs with fractionation and unidentified nuclear effects CAIs chondrites. Considering the apparently early and short duration (<0.3 Ma) of condensation of refractory 16O-rich solids in the SS, we infer that 26Al was injected into the collapsing protosolar molecular cloud and later homogenized in the protoplanetary disk. The apparent lack of correlation between 26Al abundance and O-isotope composition of corundum grains constrains the stellar source of 26Al in the SS.

  14. 3H-tetracycline as a proxy for 41Ca for measuring dietary perturbations of bone resorption

    NASA Astrophysics Data System (ADS)

    Weaver, Connie; Cheong, Jennifer; Jackson, George; Elmore, David; McCabe, George; Martin, Berdine

    2007-06-01

    Our group is interested in evaluating early effects of dietary interventions on bone loss. Postmenopausal women lose bone following reduction in estrogen which leads to increased risk of fracture. Traditional means of monitoring bone loss and effectiveness of treatments include changes in bone density, which takes 6 months to years to observe effects, and changes in biochemical markers of bone turnover, which are highly variable and lack specificity. Prelabeling bone with 41Ca and measuring urinary 41Ca excretion with accelerator mass spectrometry provides a sensitive, specific, and rapid approach to evaluating effectiveness of treatment. To better understand 41Ca technology as a tool for measuring effective treatments on reducing bone resorption, we perturbed bone resorption by manipulating dietary calcium in rats. We used 3H-tetracycline (3H-TC) as a proxy for 41Ca and found that a single dose is feasible to study bone resorption. Suppression of bone resorption, as measured by urinary 3H-TC, by dietary calcium was observed in rats stabilized after ovariectomy, but not in recently ovariectomized rats.

  15. {sup 41}Ca as a tracer for calcium uptake and deposition in heart tissue during ischemia and reperfusion

    SciTech Connect

    Southon, J.R.; Bishop, M.S.; Kost, G.J.

    1993-09-17

    We have developed techniques and are commencing experiments using enriched {sup 41}Ca as a tracer in isolated rabbit heart preparations. The aims of the study are to measure calcium uptake and deposition in response to cardiac ischemia and reperfusion, and to investigate events and mechanism leading to irreversible myocyte injury.

  16. Production of 26Al by super-AGB stars

    NASA Astrophysics Data System (ADS)

    Siess, L.; Arnould, M.

    2008-10-01

    Context: Super AGB (SAGB) stars have initial masses ranging between 7-11 {M_⊙} and develop efficient hydrogen burning at the base of their convective envelope during their AGB evolution, leading to a substantial production of {}26Alg. Aims: We present the first discussion of the contribution of the SAGB stars to the galactic {}26Alg production, and we estimate the main uncertainties that affect the determination of the {}26Alg yields. Methods: The results of full stellar evolution computations are presented, with special emphasis on the {}26Alg yields from SAGB stars. We also use a postprocessing nucleosynthesis code to quantify the uncertainties associated with the nuclear reaction rates and with the treatment of convection that modifies the thermodynamical conditions at the base of the convective envelope. Results: Hot bottom burning leads to individual SAGB {}26Alg yields that are larger than those from intermediate mass stars, amounting to typical values as high as 5 × 10-5 {M_⊙}. The overall SAGB contribution remains modest, however, not exceeding 0.3 {M_⊙} of the estimated galactic content of 2.8 {M_⊙}. On the other hand, the SAGB 26Al/27Al ratios always exceed 0.01, which is commensurable with the values measured in some SiC grains considered to originate in C-rich AGB stars. However, the isotopic composition of some other elements, particularly nitrogen, is clearly at variance with the observations. We find that the {}26Alg yields are not affected by the pollution induced by the third dredge-ups, but that they strongly depend on the evolution of the temperature at the base of the convective envelope, the determination of which remains highly dependent on the specific convection model used in the stellar computations. Modifications of T_env by ± 10% leads to variations in the {}26Alg yields by a factor of 0.2 to 6. In comparison, the nuclear reaction rate uncertainties have less of an impact, altering the yields by less than a factor of 2.

  17. "Groundwater ages" of the Lake Chad multi-layer aquifers system inferred from 14C and 36Cl data

    NASA Astrophysics Data System (ADS)

    Bouchez, Camille; Deschamps, Pierre; Goncalves, Julio; Hamelin, Bruno; Seidel, Jean-Luc; Doumnang, Jean-Claude

    2014-05-01

    Assessment of recharge, paleo-recharge and groundwater residence time of aquifer systems of the Sahel is pivotal for a sustainable management of this vulnerable resource. Due to its stratified aquifer system, the Lake Chad Basin (LCB) offers the opportunity to assess recharge processes over time and to link climate and hydrology in the Sahel. Located in north-central Africa at the fringe between the Sahel and the Sahara, the lake Chad basin (LCB) is an endorheic basin of 2,5.106 km2. With a monsoon climate, the majority of the rainfall occurs in the southern one third of the basin, the Chari/Logone River system transporting about 90% of the runoff generated within the drainage basin. A complex multi-layer aquifer system is located in the central part of the LCB. The Quaternary unconfined aquifer, covering 500 000 km2, is characterized by the occurrence of poorly understood piezometric depressions. Artesian groundwaters are found in the Plio-Pleistocene lacustrine and deltaic sedimentary aquifers (early Pliocene and Continental Terminal). The present-day lake is in hydraulic contact with the Quaternary Aquifer, but during past megalake phases, most of the Quaternary aquifer was submerged and may experience major recharge events. To identify active recharge area and assess groundwater dynamics, one hundred surface and groundwater samples of all layers have been collected over the southern part of the LCB. Major and trace elements have been analyzed. Measurements of 36Cl have been carried out at CEREGE, on the French 5 MV AMS National Facility ASTER and 14C activities have been analyzed for 17 samples on the French AMS ARTEMIS. Additionally, the stable isotopic composition was measured on the artesian aquifer samples. In the Quaternary aquifer, results show a large scatter with waters having very different isotopic and geochemical signature. In its southern part and in the vicinity of the surface waters, groundwaters are predominantly Ca-Mg-HCO3 type waters with very

  18. 26Al-containing acidic and basic sodium aluminum phosphate preparation and use in studies of oral aluminum bioavailability from foods utilizing 26Al as an aluminum tracer

    NASA Astrophysics Data System (ADS)

    Yokel, Robert A.; Urbas, Aaron A.; Lodder, Robert A.; Selegue, John P.; Florence, Rebecca L.

    2005-04-01

    We synthesized 26Al-containing acidic and basic (alkaline) sodium aluminum phosphates (SALPs) which are FDA-approved leavening and emulsifying agents, respectively, and used them to determine the oral bioavailability of aluminum incorporated in selected foods. We selected applicable methods from published syntheses (patents) and scaled them down (∼3000- and 850-fold) to prepare ∼300-400 mg of each SALP. The 26Al was incorporated at the beginning of the syntheses to maximize 26Al and 27Al equilibration and incorporate the 26Al in the naturally-occurring Al-containing chemical species of the products. Near infrared spectroscopy (NIR) and X-ray powder diffraction (XRD) were used to characterize the two SALP samples and some intermediate samples. Multi-elemental analysis (MEA) was used to determine Na, Al and P content. Commercial products were included for comparison. Satisfactory XRD analyses, near infrared spectra and MEA results confirmed that we synthesized acidic and basic SALP, as well as some of the syntheses intermediates. The 26Al-containing acidic and basic SALPs were incorporated into a biscuit material and a processed cheese, respectively. These were used in oral bioavailability studies conducted in rats in which the 26Al present in blood after its oral absorption was quantified by accelerator mass spectrometry. The results showed oral Al bioavailability from acidic SALP in biscuit was ∼0.02% and from basic SALP in cheese ∼0.05%, lower than our previous determination of Al bioavailability from drinking water, ∼0.3%. Both food and water can appreciably contribute to the Al absorbed from typical human Al intake.

  19. Timing of maximum glacial extent and deglaciation from HualcaHualca volcano (southern Peru), obtained with cosmogenic 36Cl.

    NASA Astrophysics Data System (ADS)

    Alcalá, Jesus; Palacios, David; Vazquez, Lorenzo; Juan Zamorano, Jose

    2015-04-01

    Andean glacial deposits are key records of climate fluctuations in the southern hemisphere. During the last decades, in situ cosmogenic nuclides have provided fresh and significant dates to determine past glacier behavior in this region. But still there are many important discrepancies such as the impact of Last Glacial Maximum or the influence of Late Glacial climatic events on glacial mass balances. Furthermore, glacial chronologies from many sites are still missing, such as HualcaHualca (15° 43' S; 71° 52' W; 6,025 masl), a high volcano of the Peruvian Andes located 70 km northwest of Arequipa. The goal of this study is to establish the age of the Maximum Glacier Extent (MGE) and deglaciation at HualcaHualca volcano. To achieve this objetive, we focused in four valleys (Huayuray, Pujro Huayjo, Mollebaya and Mucurca) characterized by a well-preserved sequence of moraines and roches moutonnées. The method is based on geomorphological analysis supported by cosmogenic 36Cl surface exposure dating. 36Cl ages have been estimated with the CHLOE calculator and were compared with other central Andean glacial chronologies as well as paleoclimatological proxies. In Huayuray valley, exposure ages indicates that MGE occurred ~ 18 - 16 ka. Later, the ice mass gradually retreated but this process was interrupted by at least two readvances; the last one has been dated at ~ 12 ka. In the other hand, 36Cl result reflects a MGE age of ~ 13 ka in Mollebaya valley. Also, two samples obtained in Pujro-Huayjo and Mucurca valleys associated with MGE have an exposure age of 10-9 ka, but likely are moraine boulders affected by exhumation or erosion processes. Deglaciation in HualcaHualca volcano began abruptly ~ 11.5 ka ago according to a 36Cl age from a polished and striated bedrock in Pujro Huayjo valley, presumably as a result of reduced precipitation as well as a global increase of temperatures. The glacier evolution at HualcaHualca volcano presents a high correlation with

  20. Seismic slip history of the Pizzalto fault (Central Apennines, Italy) using in situ 36Cl cosmogenic dating

    NASA Astrophysics Data System (ADS)

    Delli Rocioli, Mattia; Pace, Bruno; Benedetti, Lucilla; Visini, Francesco; Guillou, Valery; Bourlès, Didier; Arnorld, Maurice; Aumaître, Georges; Keddadouche, Karim

    2013-04-01

    A prerequisite to constrain fault-based and time-dependent earthquake rupture forecast models is to acquire data on the past large earthquake frequency on an individual seismogenic source. Here we present a paleoseismological study on the Pizzalto fault using the in situ produced cosmogenic nuclide 36Cl (Schlagenhauf et al., 2011). The Pizzalto fault, located in central Italy about 50 km southeast of the epicenter of L'Aquila 2009 earthquake, is about 12 km long, SW dipping and belongs to the 30 km long Rotella-Aremogna active normal fault system. Recent activity along the Pizzalto fault is suggested by the presence of a continuous and linear 2 to 5 m high limestone fault scarp that was sampled every 10 cm at a site located in its particularly well-preserved central portion. 49 samples have been chemically processed and measured, and their 36Cl and Cl concentrations have been determined using isotope dilution mass spectrometry at the French AMS national facility ASTER located at CEREGE. Modeling the in situ 36Cl concentration with the scarp height allow deciphering the age and slip of the last major earthquake events on the fault. To derive those earthquake parameters, we used the published Matlab code from Schlagenhauf et al. (2011) that we implemented with a Monte Carlo approach to explore a large number of earthquake recurrence scenarios varying both the number of events, their slip and their ages. The "a priori" constraints input in the Monte Carlo code were: 1-the number of events, which is given by the stacking of individual probability density functions (assumed to be Gaussian) of each sample concentration; and, 2-the cumulative slip that should be equal to the height of the fault scarp. The first results show that 36Cl concentrations are reproduced better considering five events occurring over the last 5 ka and a previous one at about 13 ka. This suggests that most earthquake events clustered during a period of intense seismic activity preceded by a longer

  1. Translocation of 125I, 75Se and 36Cl to wheat edible parts following wet foliar contamination under field conditions.

    PubMed

    Hurtevent, P; Thiry, Y; Levchuk, S; Yoschenko, V; Henner, P; Madoz-Escande, C; Leclerc, E; Colle, C; Kashparov, V

    2013-07-01

    Apart from radiocaesium and radiostrontium, there have been few studies on the foliar transfer of radionuclides in plants. Consequently, specific translocation factor (ftr) values for (129)I, (79)Se and (36)Cl are still missing from the IAEA reference databases. The translocation of short - lived isotopes, (125)I and (75)Se, and of (36)Cl to wheat grain were measured under field conditions following acute and chronic wet foliar contamination at various plant growth stages in the absence of leaching caused by rain. The translocation factors ranged from 0.02% to 1.1% for (125)I (a value similar to Sr), from 0.1% to 16.5% for (75)Se, and from 1% to 14.9% for (36)Cl. Both (36)Cl and (75)Se were as mobile as Cs. The phenomenological analysis showed that each element displayed a specific behavior. Iodide showed the lowest apparent mobility because of its preferential fixation in or on the leaves and a significant amount probably volatilized. Selenite internal transfer was significant and possibly utilized the sulphur metabolic pathway. However bio - methylation of selenite may have led to increased volatilization. Chloride was very mobile and quickly diffused throughout the plant. In addition, the analysis underlined the importance of plant growth responses to annual variations in weather conditions that can affect open field experiments because plant growth stage played a major role in ftr values dispersion. The chronic contamination results suggested that a series of acute contamination events had an additive effect on translocated elements. The highest translocation value obtained for an acute contamination event was shown to be a good conservative assessment of chronic contamination if data on chronic contamination translocation are lacking. The absence of rain leaching during the experiment meant that this investigation avoided potential radionuclide transfer by the roots, which also meant that radionuclide retention on or in the leaves was maximized. This study was

  2. PRIME Lab Radiocarbon Measurements

    NASA Astrophysics Data System (ADS)

    Hillegonds, D. J.; Mueller, K. A.; Ma, X.; Lipschutz, M. E.

    1996-03-01

    The Purdue Rare Isotope Measurement Laboratory (PRIME Lab) is one of three NSF national facilities for accelerator mass spectrometry (AMS), and is the only one capable of determining six cosmogenic radionuclides: 10Be, 14C, 26Al, 36Cl, 41Ca, and 129I. This abstract describes the current status of the radiocarbon analysis program at PRIME Lab.

  3. A pilot study of the feasibility of long-term human bone balance during perimenopause using a 41Ca tracer

    NASA Astrophysics Data System (ADS)

    Hui, S. K.; Prior, J.; Gelbart, Z.; Johnson, R. R.; Lentle, B. C.; Paul, M.

    2007-06-01

    The mechanisms governing calcium fluxes during bone remodeling processes in perimenopausal women are poorly known. Despite higher, albeit erratic, estradiol levels in perimenopause, spine bone loss is greater than during the first five years past the final menstrual flow when estradiol becomes low. Understanding changes during this dynamic transition are important to prevent fragility fractures in midlife and older women. The exploration of long-lived 41Ca (T1/2 = 1.04 × 105 yrs) tracer measurements using accelerator mass spectrometry (AMS) leads to the possibility of monitoring bone remodeling balance. With this new technology, we explored a pilot long-term feasibility study of bone health by measuring the 41Ca trace element in urine for six years from premenopausal to later perimenopausal phases in one midlife woman. We measured bone mineral density in parallel.

  4. Tritium and 36Cl as constraints on fast fracture flow and percolation flux in the unsaturated zone at Yucca Mountain

    NASA Astrophysics Data System (ADS)

    Guerin, Marianne

    2001-10-01

    An analysis of tritium and 36Cl data collected at Yucca Mountain, Nevada suggests that fracture flow may occur at high velocities through the thick unsaturated zone. The mechanisms and extent of this "fast flow" in fractures at Yucca Mountain are investigated with data analysis, mixing models and several one-dimensional modeling scenarios. The model results and data analysis provide evidence substantiating the weeps model [Gauthier, J.H., Wilson, M.L., Lauffer, F.C., 1992. Proceedings of the Third Annual International High-level Radioactive Waste Management Conference, vol. 1, Las Vegas, NV. American Nuclear Society, La Grange Park, IL, pp. 891-989] and suggest that fast flow in fractures with minimal fracture-matrix interaction may comprise a substantial proportion of the total infiltration through Yucca Mountain. Mixing calculations suggest that bomb-pulse tritium measurements, in general, represent the tail end of travel times for thermonuclear-test-era (bomb-pulse) infiltration. The data analysis shows that bomb-pulse tritium and 36Cl measurements are correlated with discrete features such as horizontal fractures and areas where lateral flow may occur. The results presented here imply that fast flow in fractures may be ubiquitous at Yucca Mountain, occurring when transient infiltration (storms) generates flow in the connected fracture network.

  5. Tritium and 36Cl as constraints on fast fracture flow and percolation flux in the unsaturated zone at Yucca Mountain.

    PubMed

    Guerin, M

    2001-10-01

    An analysis of tritium and 36Cl data collected at Yucca Mountain, Nevada suggests that fracture flow may occur at high velocities through the thick unsaturated zone. The mechanisms and extent of this "fast flow" in fractures at Yucca Mountain are investigated with data analysis, mixing models and several one-dimensional modeling scenarios. The model results and data analysis provide evidence substantiating the weeps model [Gauthier, J.H., Wilson, M.L., Lauffer, F.C., 1992. Proceedings of the Third Annual International High-level Radioactive Waste Management Conference, vol. 1, Las Vegas, NV. American Nuclear Society, La Grange Park, IL, pp. 891-989] and suggest that fast flow in fractures with minimal fracture-matrix interaction may comprise a substantial proportion of the total infiltration through Yucca Mountain. Mixing calculations suggest that bomb-pulse tritium measurements, in general, represent the tail end of travel times for thermonuclear-test-era (bomb-pulse) infiltration. The data analysis shows that bomb-pulse tritium and 36Cl measurements are correlated with discrete features such as horizontal fractures and areas where lateral flow may occur. The results presented here imply that fast flow in fractures may be ubiquitous at Yucca Mountain, occurring when transient infiltration (storms) generates flow in the connected fracture network. PMID:11588829

  6. Tritium and 36Cl as constraints on fast fracture flow and percolation flux in the unsaturated zone at Yucca Mountain.

    PubMed

    Guerin, M

    2001-10-01

    An analysis of tritium and 36Cl data collected at Yucca Mountain, Nevada suggests that fracture flow may occur at high velocities through the thick unsaturated zone. The mechanisms and extent of this "fast flow" in fractures at Yucca Mountain are investigated with data analysis, mixing models and several one-dimensional modeling scenarios. The model results and data analysis provide evidence substantiating the weeps model [Gauthier, J.H., Wilson, M.L., Lauffer, F.C., 1992. Proceedings of the Third Annual International High-level Radioactive Waste Management Conference, vol. 1, Las Vegas, NV. American Nuclear Society, La Grange Park, IL, pp. 891-989] and suggest that fast flow in fractures with minimal fracture-matrix interaction may comprise a substantial proportion of the total infiltration through Yucca Mountain. Mixing calculations suggest that bomb-pulse tritium measurements, in general, represent the tail end of travel times for thermonuclear-test-era (bomb-pulse) infiltration. The data analysis shows that bomb-pulse tritium and 36Cl measurements are correlated with discrete features such as horizontal fractures and areas where lateral flow may occur. The results presented here imply that fast flow in fractures may be ubiquitous at Yucca Mountain, occurring when transient infiltration (storms) generates flow in the connected fracture network.

  7. HETEROGENEOUS DISTRIBUTION OF {sup 26}Al AT THE BIRTH OF THE SOLAR SYSTEM

    SciTech Connect

    Makide, Kentaro; Nagashima, Kazuhide; Krot, Alexander N.; Huss, Gary R.; Ciesla, Fred J.; Yang, Le; Hellebrand, Eric; Gaidos, Eric

    2011-06-01

    It is believed that {sup 26}Al, a short-lived (t{sub 1/2} = 0.73 Ma) and now extinct radionuclide, was uniformly distributed in the nascent solar system (SS) with the initial {sup 26}Al/{sup 27}Al ratio of {approx}5.2 x 10{sup -5}, suggesting an external, stellar origin rather than local, solar source. However, the stellar source of {sup 26}Al and the manner in which it was injected into the SS remain controversial: the {sup 26}Al could have been produced by an asymptotic giant branch star, a supernova, or a Wolf-Rayet star and injected either into the protosolar molecular cloud, protosolar cloud core, or protoplanetary disk. Corundum (Al{sub 2}O{sub 3}) is predicted to be the first condensate from a cooling gas of solar composition. Here we show that micron-sized corundum condensates from {sup 16}O-rich ({Delta}{sup 17}O {approx} -25 per mille ) gas of solar composition recorded heterogeneous distribution of {sup 26}Al at the birth of the SS: the inferred initial {sup 26}Al/{sup 27}Al ratio ranges from {approx}6.5x10{sup -5} to <2x10{sup -6}; 52% of corundum grains measured are {sup 26}Al-poor. Abundant {sup 26}Al-poor, {sup 16}O-rich refractory objects include grossite- and hibonite-rich calcium-aluminum-rich inclusions (CAIs) in CH (high metal abundance and high iron concentration) chondrites, platy hibonite crystals in CM (Mighei-like) chondrites, and CAIs with fractionation and unidentified nuclear effects CAIs chondrites. Considering the apparently early and short duration (<0.3 Ma) of condensation of refractory {sup 16}O-rich solids in the SS, we infer that {sup 26}Al was injected into the collapsing protosolar molecular cloud and later homogenized in the protoplanetary disk. The apparent lack of correlation between {sup 26}Al abundance and O-isotope composition of corundum grains constrains the stellar source of {sup 26}Al in the SS.

  8. {sup 26}Al IN THE EARLY SOLAR SYSTEM: NOT SO UNUSUAL AFTER ALL

    SciTech Connect

    Jura, M.; Xu, S.; Young, E. D. E-mail: sxu@astro.ucla.edu

    2013-10-01

    Recently acquired evidence shows that extrasolar asteroids exhibit over a factor of 100 variation in the iron to aluminum abundance ratio. This large range likely is a consequence of igneous differentiation that resulted from heating produced by radioactive decay of {sup 26}Al with an abundance comparable to that in the solar system's protoplanetary disk at birth. If so, the conventional view that our solar system began with an unusually high amount of {sup 26}Al should be discarded.

  9. 26Al- 26Mg and 207Pb- 206Pb systematics of Allende CAIs: Canonical solar initial 26Al/ 27Al ratio reinstated

    NASA Astrophysics Data System (ADS)

    Jacobsen, Benjamin; Yin, Qing-zhu; Moynier, Frederic; Amelin, Yuri; Krot, Alexander N.; Nagashima, Kazuhide; Hutcheon, Ian D.; Palme, Herbert

    2008-07-01

    The precise knowledge of the initial 26Al/ 27Al ratio [( 26Al/ 27Al) 0] is crucial if we are to use the very first solid objects formed in our Solar System, calcium-aluminum-rich inclusions (CAIs) as the "time zero" age-anchor and guide future work with other short-lived radio-chronometers in the early Solar System, as well as determining the inventory of heat budgets from radioactivities for early planetary differentiation. New high-precision multi-collector inductively-coupled plasma mass spectrometry (MC-ICP-MS) measurements of 27Al/ 24Mg ratios and Mg-isotopic compositions of nine whole-rock CAIs (six mineralogically characterized fragments and three micro-drilled inclusions) from the CV carbonaceous chondrite, Allende yield a well-defined 26Al- 26Mg fossil isochron with an ( 26Al/ 27Al) 0 of (5.23 ± 0.13) × 10 - 5 . Internal mineral isochrons obtained for three of these CAIs ( A44A, AJEF, and A43) are consistent with the whole-rock CAI isochron. The mineral isochron of AJEF with ( 26Al/ 27Al) 0 = (4.96 ± 0.25) × 10 - 5 , anchored to our precisely determined absolute 207Pb- 206Pb age of 4567.60 ± 0.36 Ma for the same mineral separates, reinstate the "canonical" ( 26Al/ 27Al) 0 of 5 × 10 - 5 for the early Solar System. The uncertainty in ( 26Al/ 27Al) 0 corresponds to a maximum time span of ± 20 Ka (thousand years), suggesting that the Allende CAI formation events were culminated within this time span. Although all Allende CAIs studied experienced multistage formation history, including melting and evaporation in the solar nebula and post-crystallization alteration likely on the asteroidal parent body, the 26Al- 26Mg and U-Pb-isotopic systematics of the mineral separates and bulk CAIs behaved largely as closed-system since their formation. Our data do not support the "supra-canonical" 26Al/ 27Al ratio of individual minerals or their mixtures in CV CAIs, suggesting that the supra-canonical 26Al/ 27Al ratio in the CV CAIs may have resulted from post

  10. Millennial strain partitioning and fault interaction revealed by 36Cl cosmogenic nuclide datasets from Abruzzo, Central Italy

    NASA Astrophysics Data System (ADS)

    Gregory, L. C.; Phillips, R. J.; Roberts, G.; Cowie, P. A.; Shanks, R. P.; McCaffrey, K. J. W.; Wedmore, L. N. J.; Zijerveld, L.

    2015-12-01

    In zones of distributed continental faulting, it is critical to understand how slip is partitioned onto brittle structures over both long-term millennial time scales and shorter-term individual earthquake cycles. The comparison of slip distributions on different timescales is challenging due to earthquake repeat-times being longer or similar to historical earthquake records, and a paucity of data on fault activity covering millennial to Quaternary scales in detail. Cosmogenic isotope analyses from bedrock fault scarps have the potential to bridge the gap, as these datasets track the exposure of fault planes due to earthquakes with better-than-millennial resolution. In this presentation, we will use an extensive 36Cl dataset to characterise late Holocene activity across a complicated network of normal faults in Abruzzo, Italy, comparing the most recent fault behaviour with the historical earthquake record in the region. Extensional faulting in Abruzzo has produced scarps of exposed bedrock limestone fault planes that have been preserved since the last glacial maximum (LGM). 36Cl accumulates in bedrock fault scarps as the plane is progressively exhumed by earthquakes and thus the concentration of 36Cl measured up the fault plane reflects the rate and patterns of slip. In this presentation, we will focus on the most recent record, revealed at the base of the fault. Utilising new Bayesian modelling techniques on new and previously collected data, we compare evidence for this most recent period of slip (over the last several thousands of years) across 5-6 fault zones located across strike from each other. Each sampling site is carefully characterised using LiDAR and GPR. We demonstrate that the rate of slip on individual fault strands varies significantly, between having periods of accelerated slip to relative quiescence. Where data is compared between across-strike fault zones and with the historical catalogue, it appears that slip is partitioned such that one fault

  11. Heating and melting of small icy satellites by the decay of 26Al

    NASA Technical Reports Server (NTRS)

    Prialnik, D.; Bar-Nun, A.; Owen, T. (Principal Investigator)

    1990-01-01

    We study the effect of radiogenic heating due to 26Al on the thermal evolution of small icy satellites. Our object is to find the extent of internal melting as a function of the satellite radius and of the initial 26Al abundance. The implicit assumption, based on observations of young stars, is that planet and satellite accretion occurred on a time scale of approximately 10(6) yr (comparable with the lifetime of 26Al). The icy satellites are modeled as spheres of initially amorphous ice, with chondritic abundances of 40K, 232Th, 235U, 238U, corresponding to an ice/dust mass ratio of 1. Evolutionary calculations are carried out, spanning 4.5 x 10(9) yr, for different combinations of the two free parameters. Heat transfer by subsolidus convection is neglected for these small satellites. Our main conclusion is that the initial 26Al abundance capable of melting icy bodies of satellite size to a significant extent is more than 10 times lower than that prevailing in the interstellar medium (or that inferred from the Ca-Al rich inclusions of the Allende meteorite, approximately 7 x 10(-7) by mass). We find, for example, that an initial 26Al mass fraction of approximately 4 x 10(-8) is sufficient for melting almost completely icy spheres with radii of 800 km, typical of the larger icy planetary satellites. We also find that for any given 26Al abundance, there is a narrow range of radii below which only marginal melting occurs and above which most of the ice melts (and refreezes later). Since extensive melting may have important consequences, such as differentiation, gas release, and volcanic activity, the effect of 26Al should be included in future studies of satellite interiors.

  12. Early accretion of protoplanets inferred from a reduced inner solar system 26Al inventory

    NASA Astrophysics Data System (ADS)

    Schiller, Martin; Connelly, James N.; Glad, Aslaug C.; Mikouchi, Takashi; Bizzarro, Martin

    2015-06-01

    The mechanisms and timescales of accretion of 10-1000 km sized planetesimals, the building blocks of planets, are not yet well understood. With planetesimal melting predominantly driven by the decay of the short-lived radionuclide 26Al (26Al→26Mg; t1/2 = 0.73 Ma), its initial abundance determines the permissible timeframe of planetesimal-scale melting and its subsequent cooling history. Currently, precise knowledge about the initial 26Al abundance [(26Al/27Al)0] exists only for the oldest known solids, calcium aluminum-rich inclusions (CAIs) - the so-called canonical value. We have determined the 26Al/27Al of three angrite meteorites, D'Orbigny, Sahara 99555 and NWA 1670, at their time of crystallization, which corresponds to (3.98 ± 0.15) ×10-7, (3.64 ± 0.18) ×10-7, and (5.92 ± 0.59) ×10-7, respectively. Combined with a newly determined absolute U-corrected Pb-Pb age for NWA 1670 of 4564.39 ± 0.24 Ma and published U-corrected Pb-Pb ages for the other two angrites, this allows us to calculate an initial (26Al/27Al)0 of (1.33-0.18+0.21) ×10-5 for the angrite parent body (APB) precursor material at the time of CAI formation, a value four times lower than the accepted canonical value of 5.25 ×10-5. Based on their similar 54Cr/52Cr ratios, most inner solar system materials likely accreted from material containing a similar 26Al/27Al ratio as the APB precursor at the time of CAI formation. To satisfy the abundant evidence for widespread planetesimal differentiation, the subcanonical 26Al budget requires that differentiated planetesimals, and hence protoplanets, accreted rapidly within 0.25 ± 0.15 Ma of the formation of canonical CAIs.

  13. Heating and melting of small icy satellites by the decay of 26Al.

    PubMed

    Prialnik, D; Bar-Nun, A

    1990-05-20

    We study the effect of radiogenic heating due to 26Al on the thermal evolution of small icy satellites. Our object is to find the extent of internal melting as a function of the satellite radius and of the initial 26Al abundance. The implicit assumption, based on observations of young stars, is that planet and satellite accretion occurred on a time scale of approximately 10(6) yr (comparable with the lifetime of 26Al). The icy satellites are modeled as spheres of initially amorphous ice, with chondritic abundances of 40K, 232Th, 235U, 238U, corresponding to an ice/dust mass ratio of 1. Evolutionary calculations are carried out, spanning 4.5 x 10(9) yr, for different combinations of the two free parameters. Heat transfer by subsolidus convection is neglected for these small satellites. Our main conclusion is that the initial 26Al abundance capable of melting icy bodies of satellite size to a significant extent is more than 10 times lower than that prevailing in the interstellar medium (or that inferred from the Ca-Al rich inclusions of the Allende meteorite, approximately 7 x 10(-7) by mass). We find, for example, that an initial 26Al mass fraction of approximately 4 x 10(-8) is sufficient for melting almost completely icy spheres with radii of 800 km, typical of the larger icy planetary satellites. We also find that for any given 26Al abundance, there is a narrow range of radii below which only marginal melting occurs and above which most of the ice melts (and refreezes later). Since extensive melting may have important consequences, such as differentiation, gas release, and volcanic activity, the effect of 26Al should be included in future studies of satellite interiors.

  14. A comparison of groundwater dating with 81Kr, 36Cl and 4He in four wells of the Great Artesian Basin, Australia

    NASA Astrophysics Data System (ADS)

    Lehmann, B. E.; Love, A.; Purtschert, R.; Collon, P.; Loosli, H. H.; Kutschera, W.; Beyerle, U.; Aeschbach-Hertig, W.; Kipfer, R.; Frape, S. K.; Herczeg, A.; Moran, J.; Tolstikhin, I. N.; Gröning, M.

    2003-06-01

    The isotopic ratios 81Kr/Kr and 36Cl/Cl and the 4He concentrations measured in groundwater from four artesian wells in the western part of the Great Artesian Basin (GAB) in Australia are discussed. Based on radioactive decay along a water flow path the 81Kr/Kr ratios are directly converted to groundwater residence times. Results are in a range of 225-400 kyr with error bars in the order of 15% primarily due to counting statistics in the cyclotron accelerator mass spectrometer measurement. Additional uncertainties from subsurface production and/or exchange with stagnant porewaters in the confining shales appear to be of the same order of magnitude. These 81Kr ages are then used to calibrate the 36Cl and the 4He dating methods. Based on elemental analyses of rock samples from the sandstone aquifer as well as from the confining Bulldog shale the in situ flux of thermal neutrons and the corresponding 3He/ 4He and 36Cl/Cl ratios are calculated. From a comparison of: (i) the 3He/ 4He ratios measured in the groundwater samples with the calculated in situ ratios in rocks and (ii) the measured δ 37Cl ratios with the 4He concentrations measured in groundwater it is concluded that both helium and chloride are most likely added to the aquifer from sources in the stagnant porewaters of the confining shale by diffusion and/or mixing. Based on this 'working hypothesis' the 36Cl transport equation in groundwater is solved taking into account: (i) radioactive decay, (ii) subsurface production in the sandstone aquifer (with an in situ 36Cl/Cl ratio of 6×10 -15) and (iii) addition of chloride from a source in the confining shale (with a 36Cl/Cl ratio of 13×10 -15). Lacking better information it is assumed that the chloride concentration increased linearly with time from an (unknown) initial value Ci to its measured present value C= Ci+ Ca, where Ca represents the (unknown) amount of chloride added from subsurface sources. Using the 81Kr ages of the four groundwater samples and a

  15. Measurement of 26Al in Iron Meteorites by Thermal Ionization Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Langellier, C.; Birck, J. L.; Allegre, C. J.

    1992-07-01

    We report here the measurement of ^26Al by thermal ionization mass spectrometry in iron meteorites. Nuclides produced by the interaction of galactic cosmic rays with meteoritic bodies are widely used to reconstruct the parental history of meteorites and also to address the problem of constancy of cosmic rays in the past. In iron meteorites the half life of ^26Al is much shorter than the exposure age and saturation is reached. Its concentration is then directly related to the preatmospheric shielding of the analyzed sample. It can be also used together, with other short-lived nuclides, to calculate the terrestrial residence time for found meteorites. Natural contents of ^26Al in iron meteorites are very small (a few dpm per kg) and have been measured earlier by counting techniques and AMS. For thermal ionization the difficulty resides mostly in the measurement of the ^26Al/^27Al ratio. ^27Al may be contained in the sample and also is introduced by the chemical separation. ^27Al beams of 10^-11 A are readily obtained with a few ng of aluminium and are measured on a standard faraday cup. ^26Al was measured on a low background electron multiplier operated in the ion counter mode. ^27Al content was measured by isotope dilution using a ^26Al spike. The ^26Al ion beam can be interfered by traces of ^26Mg. Usually the ^26Mg background could be brought lower than 10^-9 relative to ^27Al. This is sufficient for the present experiment. No organic interference was present at the same level. The abundance sensitivity stemming from the ^27Al beam on mass 26 is 3 10^-9. Results: Samples sizes for this study range from 100 to 300 mg of iron. Ratios are measured with a precision of about 1% thereby leading to a final ^26Al content with an accuracy around 2%. Two meteorites were investigated so far: Grant and Canyon Diablo. Grant is one of the best documented meteorites with regard to spallation effects. The result on Grant is an agreement with literature AMS data (Graf et al., 1987

  16. 26Al production: The Allende meteorite (Chihuahua) stellar nucleosynthesis and solar models

    NASA Astrophysics Data System (ADS)

    Araujo-Escalona, V.; Andrade, E.; Barrón-Palos, L.; Canto, C.; Favela, F.; Huerta, A.; de Lucio, O.; Ortiz, M. E.; Solís, C.; Chávez, E.

    2015-07-01

    In 1969 a meteorite fell near the small town of Allende, state of Chihuahua in the north of Mexico. Its study yielded information that changed the current understanding of the solar model. In particular traces of 26Al were found. Abundances of that isotope had been seen in the universe and were related to regions of active heavy nucleosynthesis. Its presence on the solar system was unexpected. It is now understood that cosmic rays induce nuclear reactions on materials to produce 26Al, on Earth this is well known and it is the basis of many environmental studies, so it is not only the product of some high metalicity star collapse. Taking advantage of the recently reinforced laboratory infrastructure of the Instituto de Física, at UNAM in Mexico City, we proposed to measure the cross section for 26Al production via some of the most likely reactions, from the nuclear physics point of view (highest Q-values). In this paper the study of the 28Si(d,α)26 Al nuclear reaction is shown. A target is prepared by a mixture of silicon and aluminum powders. It is irradiated with a deuteron beam (≈1 µA current) at the MV CN-Van de Graaff accelerator laboratory. The number of projectiles is deduced by Rutherford Backscattering Spectrometry (RBS). The produced 26Al nuclei are then counted at the Accelerator Mass Spectrometry Laboratory.

  17. {sup 26}Al production: The Allende meteorite (Chihuahua) stellar nucleosynthesis and solar models

    SciTech Connect

    Araujo-Escalona, V.; Andrade, E.; Barrón-Palos, L.; Canto, C.; Favela, F.; Huerta, A.; Lucio, O. de; Ortiz, M. E.; Solís, C.; Chávez, E.

    2015-07-23

    In 1969 a meteorite fell near the small town of Allende, state of Chihuahua in the north of Mexico. Its study yielded information that changed the current understanding of the solar model. In particular traces of {sup 26}Al were found. Abundances of that isotope had been seen in the universe and were related to regions of active heavy nucleosynthesis. Its presence on the solar system was unexpected. It is now understood that cosmic rays induce nuclear reactions on materials to produce {sup 26}Al, on Earth this is well known and it is the basis of many environmental studies, so it is not only the product of some high metalicity star collapse. Taking advantage of the recently reinforced laboratory infrastructure of the Instituto de Física, at UNAM in Mexico City, we proposed to measure the cross section for {sup 26}Al production via some of the most likely reactions, from the nuclear physics point of view (highest Q-values). In this paper the study of the {sup 28}Si(d,α){sup 26} Al nuclear reaction is shown. A target is prepared by a mixture of silicon and aluminum powders. It is irradiated with a deuteron beam (≈1 µA current) at the MV CN-Van de Graaff accelerator laboratory. The number of projectiles is deduced by Rutherford Backscattering Spectrometry (RBS). The produced {sup 26}Al nuclei are then counted at the Accelerator Mass Spectrometry Laboratory.

  18. Improvement of the 36Cl-AMS system at MALT using a Monte Carlo ion-trajectory simulation in a gas-filled magnet

    NASA Astrophysics Data System (ADS)

    Aze, Takahiro; Matsuzaki, Hiroyuki; Matsumura, Hiroshi; Nagai, Hisao; Fujimura, Masatsugu; Noguchi, Mayumi; Hongo, Yayoi; Yokoyama, Yusuke

    2007-06-01

    We developed and experimentally confirmed a Monte Carlo simulation code to describe the trajectories of 36Cl and 36S ions in a gas-filled magnet (GFM) at the MALT, the University of Tokyo. The simulation revealed that the central trajectories of the ions in the GFM are almost spiral and most of the 36S ions collided with the interior wall of the GFM. Based on this property of the trajectories, we have found a more advantageous condition for suppressing 36S. As a result, the background level of the 36Cl/Cl ratio was lowered to 10-15.

  19. Heterogeneous distribution of 26Al at the birth of the solar system: Evidence from refractory grains and inclusions

    NASA Astrophysics Data System (ADS)

    Krot, A. N.; Makide, K.; Nagashima, K.; Huss, G. R.; Ogliore, R. C.; Ciesla, F. J.; Yang, L.; Hellebrand, E.; Gaidos, E.

    2012-12-01

    Abstract-We review recent results on O- and Mg-isotope compositions of refractory grains (corundum, hibonite) and calcium, aluminum-rich inclusions (CAIs) from unequilibrated ordinary and carbonaceous chondrites. We show that these refractory objects originated in the presence of nebular gas enriched in 16O to varying degrees relative to the standard mean ocean water value: the Δ17OSMOW value ranges from approximately -16‰ to -35‰, and recorded heterogeneous distribution of <span class="hlt">26</span><span class="hlt">Al</span> in their formation region: the inferred (<span class="hlt">26</span><span class="hlt">Al</span>/27Al)0 ranges from approximately 6.5 × 10-5 to <2 × 10-6. There is no correlation between O- and Mg-isotope compositions of the refractory objects: <span class="hlt">26</span><span class="hlt">Al</span>-rich and <span class="hlt">26</span><span class="hlt">Al</span>-poor refractory objects have similar O-isotope compositions. We suggest that <span class="hlt">26</span><span class="hlt">Al</span> was injected into the <span class="hlt">26</span><span class="hlt">Al</span>-poor collapsing protosolar molecular cloud core, possibly by a wind from a neighboring massive star, and was later homogenized in the protoplanetary disk by radial mixing, possibly at the canonical value of <span class="hlt">26</span><span class="hlt">Al</span>/27Al ratio (approximately 5 × 10-5). The <span class="hlt">26</span><span class="hlt">Al</span>-rich and <span class="hlt">26</span><span class="hlt">Al</span>-poor refractory grains and inclusions represent different generations of refractory objects, which formed prior to and during the injection and homogenization of <span class="hlt">26</span><span class="hlt">Al</span>. Thus, the duration of formation of refractory grains and CAIs cannot be inferred from their <span class="hlt">26</span><span class="hlt">Al</span>-26Mg systematics, and the canonical (<span class="hlt">26</span><span class="hlt">Al</span>/27Al)0 does not represent the initial abundance of <span class="hlt">26</span><span class="hlt">Al</span> in the solar system; instead, it may or may not represent the average abundance of <span class="hlt">26</span><span class="hlt">Al</span> in the fully formed disk. The latter depends on the formation time of CAIs with the canonical <span class="hlt">26</span><span class="hlt">Al</span>/27Al ratio relative to the timing of complete delivery of stellar <span class="hlt">26</span><span class="hlt">Al</span> to the solar system, and the degree of its subsequent homogenization in the disk. The injection of material containing <span class="hlt">26</span><span class="hlt">Al</span> resulted in no observable changes in O-isotope composition of the solar system. Instead, the variations in O-isotope compositions between individual</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeCoA.192..279H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeCoA.192..279H"><span id="translatedtitle">Characterization of a diffusion-dominant system using chloride and chlorine isotopes (<span class="hlt">36</span><span class="hlt">Cl</span>, 37Cl) for the confining layer of the Great Artesian Basin, Australia</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hasegawa, Takuma; Nakata, Kotaro; Mahara, Yasunori; Habermehl, M. A.; Oyama, Takahiro; Higashihara, Tomohiro</p> <p>2016-11-01</p> <p>The Great Artesian Basin (GAB), Australia, one of the largest confined aquifer systems in the world, attracts great attention for groundwater dating. However, there is little information about the confining layers. Therefore, core drilling investigations were conducted to characterize the main confining layer using chloride (Cl) and chlorine isotopes (<span class="hlt">36</span><span class="hlt">Cl</span>, 37Cl) at Marree (South Australia) and Richmond (Queensland), which are near the discharge and recharge areas in the GAB, respectively. Pore water samples were collected from rock cores by squeezing and leaching. The Cl concentration, <span class="hlt">36</span><span class="hlt">Cl</span>/Cl ratio, and δ37Cl value in the confining layer decreased with depth at both Marree and Richmond. The <span class="hlt">36</span><span class="hlt">Cl</span>/Cl ratios at the shallower part of the confining layer are significantly higher than the in situ secular equilibrium (<span class="hlt">36</span><span class="hlt">Cl</span>/Clse) calculated from the chemical compositions of the rock. The <span class="hlt">36</span><span class="hlt">Cl</span>/Cl ratio logarithmically decreased with depth. The calculated <span class="hlt">36</span><span class="hlt">Cl</span>/Clse is equivalent to the lowest <span class="hlt">36</span><span class="hlt">Cl</span>/Cl ratio at Richmond. In contrast, the <span class="hlt">36</span><span class="hlt">Cl</span>/Cl ratios at Marree are higher than the calculated <span class="hlt">36</span><span class="hlt">Cl</span>/Clse. The <span class="hlt">36</span><span class="hlt">Cl</span>/Clse was reached at Richmond, but not at Marree. This probably reflects the transport time due to the difference in diffusion coefficients. The δ37Cl value becomes more negative toward the deeper levels, reaching -4.5‰ and -6.1‰ at Marree and Richmond, respectively. These results suggest that the Cl is of meteoric origin and is transported by diffusion in the confining layer. Analytical simulations using diffusion equations were conducted to reproduce excess <span class="hlt">36</span><span class="hlt">Cl</span> (36Clex), Cl, and δ37Cl. The 36Clex profile, which logarithmically decreased with depth, was reproduced by steady-state diffusion equations with radioactive decay, and the diffusion coefficients derived from the 36Clex profile were equivalent to those from the laboratory experiments. A grid-search simulation using an unsteady-state diffusion equation was conducted to reproduce the Cl and δ37Cl</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li class="active"><span>6</span></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_6 --> <div id="page_7" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li class="active"><span>7</span></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="121"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003EAEJA.....9292C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003EAEJA.....9292C"><span id="translatedtitle">B and Mg isotopic variations in Leoville mrs-06 type B1 cai:origin of 10Be and <span class="hlt">26</span><span class="hlt">Al</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chaussidon, M.; Robert, F.; Russel, S. S.; Gounelle, M.; Ash, R. D.</p> <p>2003-04-01</p> <p>The finding [1-3] in Ca-Al-rich refractory inclusions (CAI) of primitive chondrites of traces of the in situ decay of radioactive 10Be (half-life 1.5Myr) indicates that irradiation of the protosolar nebula by the young Sun in its T-Tauri phase has produced significant amounts of the Li-Be-B elements. This irradiation may have produced also some or all of the short-lived <span class="hlt">26</span><span class="hlt">Al</span> (half-life 0.7Myr) and <span class="hlt">41</span><span class="hlt">Ca</span> (half-life 0.1Myr) previously detected in CAIs. To constrain the origin of 10Be and 10Al it is important to look for coupled variations in the 10Be/9Be and <span class="hlt">26</span><span class="hlt">Al</span>/27Al ratios in CAIs and to understand the processes responsible for these variations (e.g. variations in the fluences of irradiation, secondary perturbations of the CAIs, ...) We have thus studied the Li and B isotopic compositions and the Be/Li and Be/B concentration ratios in one CAI (MRS-06) from the Leoville CV3 chondrite in which large variations of the Mg isotopic compositions showing both the in situ decay of <span class="hlt">26</span><span class="hlt">Al</span> and the secondary redistribution of Mg isotopes have been observed [4]. The results show large variations for the Li and B isotopic compositions (^7Li/^6Li ranging from 11.02±0.21 to 11.82±0.07, and 10B/11B ratios ranging from 0.2457±0.0053 to 0.2980±0.0085). The ^7Li/^6Li ratio tend to decrease towards the rim of the inclusion. The 10B/11B ratios are positively correlated with the ^9Be/11B ratios indicating the in situ decay of 10Be. However perturbations of the 10Be/B system are observed. They would correspond to an event which occurred approximately 2Myr after the formation of the CAI and the irradiation of the CAI precursors which is responsible for the 10Be observed in the core of the CAI. These perturbations seem compatible with those observed for the <span class="hlt">26</span><span class="hlt">Al</span>/Mg system but they might be due to an irradiation of the already-formed, isolated CAI which would have resulted in increased 10Be/^9Be ratios and low ^7Li/^6Li ratios in the margin of the CAI. [1] McKeegan K. D. et al. (2000</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007NIMPB.259..625H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007NIMPB.259..625H"><span id="translatedtitle">Measurement of <span class="hlt">26</span><span class="hlt">Al</span> in Antarctic ice with the MALT-AMS system at the University of Tokyo</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Horiuchi, Kazuho; Matsuzaki, Hiroyuki; Ohta, Aoi; Shibata, Yasuyuki; Motoyama, Hideaki</p> <p>2007-06-01</p> <p>We have attempted to determine the <span class="hlt">26</span><span class="hlt">Al</span> concentration of Antarctic ice sampled from the vicinity of the Dome Fuji Research Station using accelerator mass spectrometry (AMS) at MALT (MicroAnalysis Laboratory, Tandem accelerator) of the University of Tokyo. Because the expected concentration of <span class="hlt">26</span><span class="hlt">Al</span> in ice is very low, our standard procedure for the AMS measurement was re-examined and refined. The observed <span class="hlt">26</span><span class="hlt">Al</span> concentration ranged between 160 and 210 atoms g-1. The averaged value of the <span class="hlt">26</span><span class="hlt">Al</span>/10Be ratio from two samples was 1.75 ± 0.19 × 10-3, which agrees well with recently reported values for the meteoric <span class="hlt">26</span><span class="hlt">Al</span>/10Be ratio from Antarctic ice and air filter residues. This result implies the possibility of future <span class="hlt">26</span><span class="hlt">Al</span>/10Be dating of old Antarctic ice.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70016363','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70016363"><span id="translatedtitle">In situ 10Be-<span class="hlt">26</span><span class="hlt">Al</span> exposure ages at Meteor Crater, Arizona</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Nishiizumi, K.; Kohl, C.P.; Shoemaker, E.M.; Arnold, J.R.; Klein, J.; Fink, D.; Middleton, R.</p> <p>1991-01-01</p> <p>A new method of dating the surface exposure of rocks from in situ production of 10Be and <span class="hlt">26</span><span class="hlt">Al</span> has been applied to determine the age of Meteor Crater, Arizona. A lower bound on the crater age of 49,200 ?? 1,700 years has been obtained by this method. ?? 1991.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4946628','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4946628"><span id="translatedtitle">Early accretion of protoplanets inferred from a reduced inner solar system <span class="hlt">26</span><span class="hlt">Al</span> inventory</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Schiller, Martin; Connelly, James N.; Glad, Aslaug C.; Mikouchi, Takashi; Bizzarro, Martin</p> <p>2016-01-01</p> <p>The mechanisms and timescales of accretion of 10–1000 km sized planetesimals, the building blocks of planets, are not yet well understood. With planetesimal melting predominantly driven by the decay of the short-lived radionuclide <span class="hlt">26</span><span class="hlt">Al</span> (26Al→26Mg; t1/2 = 0.73 Ma), its initial abundance determines the permissible timeframe of planetesimal-scale melting and its subsequent cooling history. Currently, precise knowledge about the initial <span class="hlt">26</span><span class="hlt">Al</span> abundance [(<span class="hlt">26</span><span class="hlt">Al</span>/27Al)0] exists only for the oldest known solids, calcium aluminum-rich inclusions (CAIs) – the so-called canonical value. We have determined the <span class="hlt">26</span><span class="hlt">Al</span>/27Al of three angrite meteorites, D’Orbigny, Sahara 99555 and NWA 1670, at their time of crystallization, which corresponds to (3.98 ± 0.15)×10−7, (3.64 ± 0.18)×10−7, and (5.92 ± 0.59)×10−7, respectively. Combined with a newly determined absolute U-corrected Pb–Pb age for NWA 1670 of 4564.39 ± 0.24 Ma and published U-corrected Pb–Pb ages for the other two angrites, this allows us to calculate an initial (<span class="hlt">26</span><span class="hlt">Al</span>/27Al)0 of (1.33−0.18+0.21)×10−5 for the angrite parent body (APB) precursor material at the time of CAI formation, a value four times lower than the accepted canonical value of 5.25 × 10−5. Based on their similar 54Cr/52Cr ratios, most inner solar system materials likely accreted from material containing a similar <span class="hlt">26</span><span class="hlt">Al</span>/27Al ratio as the APB precursor at the time of CAI formation. To satisfy the abundant evidence for widespread planetesimal differentiation, the subcanonical <span class="hlt">26</span><span class="hlt">Al</span> budget requires that differentiated planetesimals, and hence protoplanets, accreted rapidly within 0.25 ± 0.15 Ma of the formation of canonical CAIs. PMID:27429474</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16151825','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16151825"><span id="translatedtitle">The Hiroshima thermal-neutron discrepancy for (<span class="hlt">36</span>)<span class="hlt">Cl</span> at large distances. Part II: Natural in situ production as a source.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nolte, Eckehart; Huber, Thomas; Rühm, Werner; Kato, Kazuo; Lazarev, Vitali; Schultz, Ludolf</p> <p>2005-10-01</p> <p>For Hiroshima, a large discrepancy between calculated and measured thermal-neutron fluences had been reported in the past, for distances to the epicenter larger than about 1,000 m. To be more specific, measured (<span class="hlt">36</span>)<span class="hlt">Cl</span> concentrations in environmental samples from Hiroshima were too large at these distances, and the ratio of measured to calculated values reached about 70, at a distance of 1,800 m. In an attempt to identify other sources that might also produce (<span class="hlt">36</span>)<span class="hlt">Cl</span> in Hiroshima samples, the role of cosmic rays and of neutrons from natural terrestrial sources was investigated. Four reaction mechanisms were taken into account: spallation reactions of the nucleonic (hadronic) component of the cosmic rays on potassium (K) and calcium (Ca) in the sample material, particle emission after nuclear capture of negative muons by K and Ca, reactions of fast-muon induced electromagnetic, and hadronic showers with K and Ca, and neutron capture reactions with (35)Cl in the sample where the neutrons originate from the above three reaction mechanisms and from uranium and thorium decay. These mechanisms are physically described and mathematically quantified. It is shown that among those parameters important for the production of (<span class="hlt">36</span>)<span class="hlt">Cl</span> in granite, the chemical composition of the sample, the depth in the quarry where the sample had initially been taken, and the erosion rate at the site of the quarry are most important. Based on these physical, chemical, and geological parameters, (<span class="hlt">36</span>)<span class="hlt">Cl</span> concentrations were calculated for different types of granite that are typical for the Hiroshima area. In samples that were of these granite types and that had not been exposed to atomic bomb(A-bomb) neutrons, the (<span class="hlt">36</span>)<span class="hlt">Cl</span> concentration was also determined experimentally by means of accelerator mass spectrometry, and good agreement was found with the calculated values. The (<span class="hlt">36</span>)<span class="hlt">Cl</span> signal due to natural in situ production was also calculated in granite samples that had been exposed to A-bomb neutrons at</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/16151825','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/16151825"><span id="translatedtitle">The Hiroshima thermal-neutron discrepancy for (<span class="hlt">36</span>)<span class="hlt">Cl</span> at large distances. Part II: Natural in situ production as a source.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nolte, Eckehart; Huber, Thomas; Rühm, Werner; Kato, Kazuo; Lazarev, Vitali; Schultz, Ludolf</p> <p>2005-10-01</p> <p>For Hiroshima, a large discrepancy between calculated and measured thermal-neutron fluences had been reported in the past, for distances to the epicenter larger than about 1,000 m. To be more specific, measured (<span class="hlt">36</span>)<span class="hlt">Cl</span> concentrations in environmental samples from Hiroshima were too large at these distances, and the ratio of measured to calculated values reached about 70, at a distance of 1,800 m. In an attempt to identify other sources that might also produce (<span class="hlt">36</span>)<span class="hlt">Cl</span> in Hiroshima samples, the role of cosmic rays and of neutrons from natural terrestrial sources was investigated. Four reaction mechanisms were taken into account: spallation reactions of the nucleonic (hadronic) component of the cosmic rays on potassium (K) and calcium (Ca) in the sample material, particle emission after nuclear capture of negative muons by K and Ca, reactions of fast-muon induced electromagnetic, and hadronic showers with K and Ca, and neutron capture reactions with (35)Cl in the sample where the neutrons originate from the above three reaction mechanisms and from uranium and thorium decay. These mechanisms are physically described and mathematically quantified. It is shown that among those parameters important for the production of (<span class="hlt">36</span>)<span class="hlt">Cl</span> in granite, the chemical composition of the sample, the depth in the quarry where the sample had initially been taken, and the erosion rate at the site of the quarry are most important. Based on these physical, chemical, and geological parameters, (<span class="hlt">36</span>)<span class="hlt">Cl</span> concentrations were calculated for different types of granite that are typical for the Hiroshima area. In samples that were of these granite types and that had not been exposed to atomic bomb(A-bomb) neutrons, the (<span class="hlt">36</span>)<span class="hlt">Cl</span> concentration was also determined experimentally by means of accelerator mass spectrometry, and good agreement was found with the calculated values. The (<span class="hlt">36</span>)<span class="hlt">Cl</span> signal due to natural in situ production was also calculated in granite samples that had been exposed to A-bomb neutrons at</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/11539739','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11539739"><span id="translatedtitle">Radiogenic heating of comets by <span class="hlt">26</span><span class="hlt">Al</span> and implications for their time of formation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Prialnik, D; Bar-Nun, A; Podolak, M</p> <p>1987-08-15</p> <p>The effect of radiogenic heating on the thermal evolution of spherical icy bodies with radii 1 km < R < 100 km was investigated. The radioisotopes considered were <span class="hlt">26</span><span class="hlt">Al</span>, 40K, 232Th, 235U, and 238U. Except for the <span class="hlt">26</span><span class="hlt">Al</span> abundance, which was varied, the other initial abundances were kept fixed, at values derived from those of chondritic meteorites and corresponding to a gas-to-dust ratio of 1. The initial models were homogeneous and isothermal (To = 10 K) amorphous ice spheres, in a circular orbit at 10(4) AU from the Sun. The main object of this study was to examine the conditions under which the transition temperature from amorphous into cubic ice (Ta = 137 K) would be reached. It was shown that the influence of the short-lived radionuclide <span class="hlt">26</span><span class="hlt">Al</span> dominates the effect of other radioactive species for bodies of radii up to approximately 50 km. Consequently, if we require comets to retain their ice in amorphous form, as suggested by observations, an upper limit of approximately 4 x 10(-9) is obtained for the initial <span class="hlt">26</span><span class="hlt">Al</span> abundance in comets, a factor of 100 lower than that of the inclusions in the Allende meteorite. A lower limit for the formation time of comets may thus be derived. The possibility of a coexistence of molten cometary cores and extended amorphous ice mantles is ruled out. Larger icy spheres (R > 100 km) reached Ta even in the absence of <span class="hlt">26</span><span class="hlt">Al</span>, due to the decay of the other radionuclides. As a result, a crystalline core formed whose relative size depended on the composition assumed. Thus the outermost icy satellites in the solar system, which might have been formed of ice in the amorphous state, have probably undergone crystallization and may have exhibited eruptive activity when the gas trapped in the amorphous ice was released (e.g., Miranda).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ApJ...826...22K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ApJ...826...22K"><span id="translatedtitle">Tracking the Distribution of <span class="hlt">26</span><span class="hlt">Al</span> and 60Fe during the Early Phases of Star and Disk Evolution</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kuffmeier, Michael; Frostholm Mogensen, Troels; Haugbølle, Troels; Bizzarro, Martin; Nordlund, Åke</p> <p>2016-07-01</p> <p>The short-lived <span class="hlt">26</span><span class="hlt">Al</span> and 60Fe radionuclides are synthesized and expelled into the interstellar medium by core-collapse supernova events. The solar system’s first solids, calcium-aluminum refractory inclusions (CAIs), contain evidence for the former presence of the <span class="hlt">26</span> <span class="hlt">Al</span> nuclide defining the canonical <span class="hlt">26</span><span class="hlt">Al</span>/27 Al ratio of ˜ 5× {10}-5. A different class of objects temporally related to canonical CAIs are CAIs with fractionation and unidentified nuclear effects (FUN CAIs), which record a low initial <span class="hlt">26</span><span class="hlt">Al</span>/27Al of 10-6. The contrasting level of <span class="hlt">26</span><span class="hlt">Al</span> between these objects is often interpreted as reflecting the admixing of the <span class="hlt">26</span><span class="hlt">Al</span> nuclides during the early formative phase of the Sun. We use giant molecular cloud scale adaptive mesh-refinement numerical simulations to trace the abundance of <span class="hlt">26</span><span class="hlt">Al</span> and 60Fe in star-forming gas during the early stages of accretion of individual low-mass protostars. We find that the <span class="hlt">26</span><span class="hlt">Al</span>/27Al and 60Fe/56Fe ratios of accreting gas within a vicinity of 1000 au of the stars follow the predicted decay curves of the initial abundances at the time of star formation without evidence of spatial or temporal heterogeneities for the first 100 kyr of star formation. Therefore, the observed differences in <span class="hlt">26</span><span class="hlt">Al</span>/27Al ratios between FUN and canonical CAIs are likely not caused by admixing of supernova material during the early evolution of the proto-Sun. Selective thermal processing of dust grains is a more viable scenario to account for the heterogeneity in <span class="hlt">26</span><span class="hlt">Al</span>/27Al ratios at the time of solar system formation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22130650','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22130650"><span id="translatedtitle">ABUNDANCE OF {sup <span class="hlt">26</span>}<span class="hlt">Al</span> AND {sup 60}Fe IN EVOLVING GIANT MOLECULAR CLOUDS</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Vasileiadis, Aristodimos; Nordlund, Ake; Bizzarro, Martin</p> <p>2013-05-20</p> <p>The nucleosynthesis and ejection of radioactive {sup <span class="hlt">26</span>}<span class="hlt">Al</span> (t{sub 1/2} {approx} 0.72 Myr) and {sup 60}Fe, (t{sub 1/2} {approx} 2.5 Myr) into the interstellar medium is dominated by the stellar winds of massive stars and supernova type II explosions. Studies of meteorites and their components indicate that the initial abundances of these short-lived radionuclides in the solar protoplanetary disk were higher than the background levels of the galaxy inferred from {gamma}-ray astronomy and models of the galactic chemical evolution. This observation has been used to argue for a late-stage addition of stellar debris to the solar system's parental molecular cloud or, alternatively, the solar protoplanetary disk, thereby requiring a special scenario for the formation of our solar system. Here, we use supercomputers to model-from first principles-the production, transport, and admixing of freshly synthesized {sup <span class="hlt">26</span>}<span class="hlt">Al</span> and {sup 60}Fe in star-forming regions within giant molecular clouds. Under typical star formation conditions, the levels of {sup <span class="hlt">26</span>}<span class="hlt">Al</span> in most star-forming regions are comparable to that deduced from meteorites, suggesting that the presence of short-lived radionuclides in the early solar system is a generic feature of the chemical evolution of giant molecular clouds. The {sup 60}Fe/{sup <span class="hlt">26</span>}<span class="hlt">Al</span> yield ratio of Almost-Equal-To 0.2 calculated from our simulations is consistent with the galactic value of 0.15 {+-} 0.06 inferred from {gamma}-ray astronomy but is significantly higher than most current solar system measurements indicate. We suggest that estimates based on differentiated meteorites and some chondritic components may not be representative of the initial {sup 60}Fe abundance of the bulk solar system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1997NIMPB.123..259K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1997NIMPB.123..259K"><span id="translatedtitle">Investigations of the human aluminium biokinetics with <span class="hlt">26</span><span class="hlt">Al</span> and AMS</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kislinger, G.; Steinhausen, C.; Alvarez-Brückmann, M.; Winklhofer, C.; Ittel, T.-H.; Nolte, E.</p> <p>1997-03-01</p> <p>Continuing the investigations on two healthy volunteers and on two patients with renal failure, the aluminium biokinetics in humans was studied by administering oral and intravenous doses of <span class="hlt">26</span><span class="hlt">Al</span> to three further healthy volunteers. Blood samples were drawn at times between 20 min and half a year after administration of the doses. The complete daily urine was collected during the first nine days, spot urine samples were taken at later times when blood samples were obtained. Creatinin renal clearances and haematocrit values were also obtained in the time period of the investigations. The <span class="hlt">26</span><span class="hlt">Al</span> concentrations of the samples were measured using the Munich Tandem accelerator. An open compartment model was developed to describe the time dependences of the measured <span class="hlt">26</span><span class="hlt">Al</span> concentrations in blood and urine and to establish the human Al biokinetics. The model comprises stomach and duodenum for oral administration, a central compartment consisting of blood plasma and interstitial fluid with transferrin and citrate binding and three peripheral compartments which are needed to describe the time dependence for the long observation period of up to three years. Excretion of Al was mainly described from plasma citrate via the kidneys into the urine and to a lesser extent from the plasma transferrin via the liver into the stool. Time constants between the compartments, fractional intestinal absorption factors and aluminium renal clearances were derived. It was found that the sizes of two peripheral compartments of the patients with renal failure were different to those of the healthy volunteers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/publication/?seqNo115=320549','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=320549"><span id="translatedtitle">Is bone equally responsive to calcium and vitamins D intake from food vs. supplements? Use of <span class="hlt">41</span><span class="hlt">Ca</span> tracer kinetic model</span></a></p> <p><a target="_blank" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p></p> <p></p> <p>Background: Few interventions directly compare equivalent calcium and vitamin D from dairy vs. supplements on the same bone outcomes. The radioisotope calcium-41 (<span class="hlt">41</span><span class="hlt">Ca</span>) holds promise as a tracer method to directly measure changes in bone resorption with differing dietary interventions. Objective: U...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeCoA.176..295L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeCoA.176..295L"><span id="translatedtitle">Accretion timescales and style of asteroidal differentiation in an <span class="hlt">26</span><span class="hlt">Al</span>-poor protoplanetary disk</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Larsen, K. K.; Schiller, M.; Bizzarro, M.</p> <p>2016-03-01</p> <p>The decay of radioactive <span class="hlt">26</span><span class="hlt">Al</span> to 26Mg (half-life of 730,000 years) is postulated to have been the main energy source promoting asteroidal melting and differentiation in the nascent solar system. High-resolution chronological information provided by the <span class="hlt">26</span><span class="hlt">Al</span>-26Mg decay system is, therefore, intrinsically linked to the thermal evolution of early-formed planetesimals. In this paper, we explore the timing and style of asteroidal differentiation by combining high-precision Mg isotope measurements of meteorites with thermal evolution models for planetesimals. In detail, we report Mg isotope data for a suite of olivine-rich [Al/Mg ∼ 0] achondritic meteorites, as well as a few chondrites. Main Group, pyroxene and the Zinder pallasites as well as the lodranite all record deficits in the mass-independent component of μ26Mg (μ26Mg∗) relative to chondrites and Earth. This isotope signal is expected for the retarded ingrowth of radiogenic 26Mg∗ in olivine-rich residues produced through partial silicate melting during <span class="hlt">26</span><span class="hlt">Al</span> decay and consistent with their marginally heavy Mg isotope composition relative to ordinary chondrites, which may reflect the early extraction of isotopically light partial melts from the source rock. We propose that their parent planetesimals started forming within ∼250,000 years of solar system formation from a hot (>∼500 K) inner protoplanetary disk region characterized by a reduced initial (<span class="hlt">26</span><span class="hlt">Al</span>/27Al)0 abundance (∼1-2 × 10-5) relative to the (<span class="hlt">26</span><span class="hlt">Al</span>/27Al)0 value in CAIs of 5.25 × 10-5. This effectively reduced the total heat production and allowed for the preservation of solid residues produced through progressive silicate melting with depth within the planetesimals. These 'non-carbonaceous' planetesimals acquired their mass throughout an extended period (>3 Myr) of continuous accretion, thereby generating onion-shell structures of incompletely differentiated zones, consisting of olivine-rich residues, overlaid by metachondrites and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1816190M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1816190M"><span id="translatedtitle">The rock avalanche of the Mt. Peron (Eastern Alps, Italy): new insights from <span class="hlt">36</span><span class="hlt">Cl</span> exposure dating</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Martin, Silvana; Ivy-ochs, Susan; Alfimov, Vasili; Vockenhuber, %Christof; Surian, Nicola; Campedel, Paolo; Rigo, Manuel; Viganò, Alfio; De Zorzi, Manuel</p> <p>2016-04-01</p> <p>In the Late Pleistocene, in the southern side of the Eastern Alps (Veneto region, Italy), when the glacier tongues retreated from the end moraine system areas towards the Dolomitic region, large rock avalanches took place. In the Belluno Valley, occupied by the Piave river, the left side is represented by the Belluno Prealps range, corresponding to the northern flank of a km-scale WSW-ENE oriented alpine syncline formed by rocks from Late Triassic to Late Tertiary in age. The Mt. Peron, belonging to this mountain range, shows its southern lower slope covered by debris cones with scattered boulders and its higher slope, corresponding to the scarp, made of vertical rock strata. At the foot of Mt. Peron, at a distance varying from 500 to 4500 m, there is a 4.5 km2 fan like area delimited by a perimeter of about 15 km. This is a hilly area of poortly sorted, chaotic deposits composed of heterogeneous debris, sandy and silty gravels, angular blocks and very large boulders of carbonatic rocks up to 20 m in diameter. The average thickness of the deposit was estimated to be 80 m, with maximum of 120 m. According to previous works, the main event occurred during the first phases of deglaciation, between 17,000 and 15,000 years BP. Popular stories narrate about two legendary villages destroyed by a mass of stones rolling down in the valley. This is confirmed by archeological findings in the Piave valley which indicate the presence of almost one pre-historic settlement dating 40000-20000 years a B.P., (i.e. before the Last Glacial Maximum).. Recent <span class="hlt">36</span><span class="hlt">Cl</span> exposure dating have yielded historical ages for both the boulders at the foot of the Mt Peron and those located a few km far from the main scarp. According to these exposure ages we can not exclude the hypothesis that earthquakes related to the Venetian faults could have played a key role for triggering of the rock avalanche and that the main gravitational event took place in historical times rather than during the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015GGG....16.2812V&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015GGG....16.2812V&link_type=ABSTRACT"><span id="translatedtitle">Late Pleistocene ages for the most recent volcanism and glacial-pluvial deposits at Big Pine volcanic field, California, USA, from cosmogenic <span class="hlt">36</span><span class="hlt">Cl</span> dating</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vazquez, J. A.; Woolford, J. M.</p> <p>2015-09-01</p> <p>The Big Pine volcanic field is one of several Quaternary volcanic fields that poses a potential volcanic hazard along the tectonically active Owens Valley of east-central California, and whose lavas are interbedded with deposits from Pleistocene glaciations in the Sierra Nevada Range. Previous geochronology indicates an ˜1.2 Ma history of volcanism, but the eruption ages and distribution of volcanic products associated with the most-recent eruptions have been poorly resolved. To delimit the timing and products of the youngest volcanism, we combine field mapping and cosmogenic <span class="hlt">36</span><span class="hlt">Cl</span> dating of basaltic lava flows in the area where lavas with youthful morphology and well-preserved flow structures are concentrated. Field mapping and petrology reveal approximately 15 vents and 6 principal flow units with variable geochemical composition and mineralogy. Cosmogenic <span class="hlt">36</span><span class="hlt">Cl</span> exposure ages for lava flow units from the top, middle, and bottom of the volcanic stratigraphy indicate eruptions at ˜17, 27, and 40 ka, revealing several different and previously unrecognized episodes of late Pleistocene volcanism. Olivine to plagioclase-pyroxene phyric basalt erupted from several vents during the most recent episode of volcanism at ˜17 ka, and produced a lava flow field covering ˜35 km2. The late Pleistocene <span class="hlt">36</span><span class="hlt">Cl</span> exposure ages indicate that moraine and pluvial shoreline deposits that overlie or modify the youngest Big Pine lavas reflect Tioga stage glaciation in the Sierra Nevada and the shore of paleo-Owens Lake during the last glacial cycle.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70157344','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70157344"><span id="translatedtitle">Late Pleistocene ages for the most recent volcanism and glacial-pluvial deposits at Big Pine volcanic field, California, USA, from cosmogenic <span class="hlt">36</span><span class="hlt">Cl</span> dating</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Vazquez, Jorge A.; Woolford, Jeff M</p> <p>2015-01-01</p> <p>The Big Pine volcanic field is one of several Quaternary volcanic fields that poses a potential volcanic hazard along the tectonically active Owens Valley of east-central California, and whose lavas are interbedded with deposits from Pleistocene glaciations in the Sierra Nevada Range. Previous geochronology indicates an ∼1.2 Ma history of volcanism, but the eruption ages and distribution of volcanic products associated with the most-recent eruptions have been poorly resolved. To delimit the timing and products of the youngest volcanism, we combine field mapping and cosmogenic <span class="hlt">36</span><span class="hlt">Cl</span> dating of basaltic lava flows in the area where lavas with youthful morphology and well-preserved flow structures are concentrated. Field mapping and petrology reveal approximately 15 vents and 6 principal flow units with variable geochemical composition and mineralogy. Cosmogenic <span class="hlt">36</span><span class="hlt">Cl</span> exposure ages for lava flow units from the top, middle, and bottom of the volcanic stratigraphy indicate eruptions at ∼17, 27, and 40 ka, revealing several different and previously unrecognized episodes of late Pleistocene volcanism. Olivine to plagioclase-pyroxene phyric basalt erupted from several vents during the most recent episode of volcanism at ∼17 ka, and produced a lava flow field covering ∼35 km2. The late Pleistocene <span class="hlt">36</span><span class="hlt">Cl</span> exposure ages indicate that moraine and pluvial shoreline deposits that overlie or modify the youngest Big Pine lavas reflect Tioga stage glaciation in the Sierra Nevada and the shore of paleo-Owens Lake during the last glacial cycle.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..15.3563Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..15.3563Z"><span id="translatedtitle">Dating chert using in-situ produced 10Be: Possible complications revealed on landslide scarps through a comparison with <span class="hlt">36</span><span class="hlt">Cl</span> applied to coexisting limestone.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zerathe, Swann; Braucher, Régis; Lebourg, Thomas; Leani, Leatitia; Manetti, Michel; Bourles, Didier</p> <p>2013-04-01</p> <p>This abstract and presentation highlights potential complications that may arise while using in situ produced 10Be to date diagenetic silica (chert)exposure or burial event. The initiation and evolution of large gravitational collapses in sedimentary rocks were constrained using cosmic ray exposure dating. Because these collapses occurred in a stratigraphic level composed of chert (diagenetic silica) concretions interbedded in limestone layers, their development was studied by performing in situ-produced <span class="hlt">36</span><span class="hlt">Cl</span> and 10Be concentration measurements in both the limestone and coexisting diagenetic silica (chert), respectively. Following the routinely used decontamination and preparation protocols for 10Be produced in diagenetic silica, large discrepancies were observed with exposure ages determined by <span class="hlt">36</span><span class="hlt">Cl</span> within carbonate for samples originating from the same scarp. While <span class="hlt">36</span><span class="hlt">Cl</span> exposure ages were clustered as expected for a unique single gravitational event, 10Be exposure ages were scattered along the same studied scarps. To determine the origin of such a bias, petrological investigations were carried out for chert (diagenetic silica). Thin sections highlighted a complex mineralogical texture characterized by remnant silicified ooids showing calcitic cores, calcite inclusions and a dominant amorphous hydrated silica (grain > 20 μm). To decipher and characterize the potential origins of the excess measured 10Be within diagenetic silica, all samples were first reprocessed following the routine decontamination protocol (HCL-H2SiF6 leachings and three partial HF dissolutions) but starting from three different grain size fractions (GS1: 1000-500, GS2: 500-250 and GS3: 250-50 μm). The resulting concentrations clearly showed a decreasing 10Be content as a function of the grain size, but still yielded 10Be exposure ages significantly higher than <span class="hlt">36</span><span class="hlt">Cl</span> counterparts. Because potential adsorption of 10Be at the surface of amorphous silica grains was suspected, partial dissolution</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4950964','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4950964"><span id="translatedtitle">Accretion timescales and style of asteroidal differentiation in an <span class="hlt">26</span><span class="hlt">Al</span>-poor protoplanetary disk</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Larsen, K.K.; Schiller, M.; Bizzarro, M.</p> <p>2016-01-01</p> <p>The decay of radioactive <span class="hlt">26</span><span class="hlt">Al</span> to 26Mg (half-life of 730,000 years) is postulated to have been the main energy source promoting asteroidal melting and differentiation in the nascent solar system. High-resolution chronological information provided by the 26Al−26Mg decay system is, therefore, intrinsically linked to the thermal evolution of early-formed planetesimals. In this paper, we explore the timing and style of asteroidal differentiation by combining high-precision Mg isotope measurements of meteorites with thermal evolution models for planetesimals. In detail, we report Mg isotope data for a suite of olivine-rich [Al/Mg ~ 0] achondritic meteorites, as well as a few chondrites. Main Group, pyroxene and the Zinder pallasites as well as the lodranite all record deficits in the mass-independent component of μ26Mg (μ26Mg*) relative to chondrites and Earth. This isotope signal is expected for the retarded ingrowth of radiogenic 26Mg* in olivine-rich residues produced through partial silicate melting during <span class="hlt">26</span><span class="hlt">Al</span> decay and consistent with their marginally heavy Mg isotope composition relative to ordinary chondrites, which may reflect the early extraction of isotopically light partial melts from the source rock. We propose that their parent planetesimals started forming within ~250,000 years of solar system formation from a hot (>~500 K) inner protoplanetary disk region characterized by a reduced initial (<span class="hlt">26</span><span class="hlt">Al</span>/27Al)0 abundance (~1–2 × 10−5) relative to the (<span class="hlt">26</span><span class="hlt">Al</span>/27Al)0 value in CAIs of 5.25 × 10−5. This effectively reduced the total heat production and allowed for the preservation of solid residues produced through progressive silicate melting with depth within the planetesimals. These ‘non-carbonaceous’ planetesimals acquired their mass throughout an extended period (>3 Myr) of continuous accretion, thereby generating onion-shell structures of incompletely differentiated zones, consisting of olivine-rich residues, overlaid by metachondrites and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001M%26PS...36..301W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001M%26PS...36..301W"><span id="translatedtitle">Cosmic-ray exposure history of two Frontier Mountain H-chondrite showers from spallation and neutron-capture products</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Welten, K. C.; Nishiizumi, K.; Masarik, J.; Caffee, M. W.; Jull, A. J. T.; Klandrud, S. E.; Wieler, R.</p> <p>2001-02-01</p> <p>We measured the concentrations of 10Be, <span class="hlt">26</span><span class="hlt">Al</span>, <span class="hlt">36</span><span class="hlt">Cl</span>, <span class="hlt">41</span><span class="hlt">Ca</span> and 14C in the metal and/or stone fractions of 27 Antarctic chondrites from Frontier Mountain (FRO), including two large H-chondrite showers. To estimate the pre-atmospheric size of the two showers, we determined the contribution of neutron-capture produced <span class="hlt">36</span><span class="hlt">Cl</span> (half-life = 3.01 ´ 105 years) and <span class="hlt">41</span><span class="hlt">Ca</span> (1.04 ´ 105 years) in the stone fraction. The measured activities of neutron-capture <span class="hlt">36</span><span class="hlt">Cl</span> and <span class="hlt">41</span><span class="hlt">Ca</span>, as well as spallation produced 10Be and <span class="hlt">26</span><span class="hlt">Al</span>, were compared with Monte Carlo-based model calculations. The largest shower, FRO 90174, includes eight fragments with an average terrestrial age of (100 ~ 30) ´ 103 years; the neutron-capture saturation activities extend to 27 dpm/kg stone for <span class="hlt">36</span><span class="hlt">Cl</span> and 19 dpm/kg stone for <span class="hlt">41</span><span class="hlt">Ca</span>. The concentrations of spallation produced 10Be, <span class="hlt">26</span><span class="hlt">Al</span> and <span class="hlt">36</span><span class="hlt">Cl</span> constrain the radius (R) to 80-100 cm, while the neutron-capture <span class="hlt">41</span><span class="hlt">Ca</span> activities indicate that the samples originated from the outer 25 cm. With a pre-atmospheric radius of 80-100 cm, FRO 90174 is among the largest of the Antarctic stony meteorites. The large pre-atmospheric size supports our hypothesis that at least 50 of the ~150 classified H5/H6-chondrites from the Frontier Mountain stranding area belong to this single fall; this hypothesis does not entirely account for the high H/L ratio at Frontier Mountain. The smaller shower, FRO 90001, includes four fragments with an average terrestrial age of (40 ~ 10) ´ 103 years; they contain small contributions of neutron-capture <span class="hlt">36</span><span class="hlt">Cl</span>, but no excess of <span class="hlt">41</span><span class="hlt">Ca</span>. FRO 90001 experienced a complex exposure history with high shielding conditions in the first stage (150 < R < 300 cm) and much lower shielding in the second stage (R < 30 cm), the latter starting ~1.0 million years (Ma) ago. Based on the measured 10Be/21Ne and <span class="hlt">26</span><span class="hlt">Al</span>/21Ne ratios, the cosmic-ray exposure ages of the two showers are 7.2 ~ 0.5 Ma for FRO 90174 and 8 ~ 1 Ma for FRO 90001. These ages coincide with the well-established H</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005AGUFM.P32A..01C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005AGUFM.P32A..01C"><span id="translatedtitle"><span class="hlt">26</span><span class="hlt">Al</span> in the Saturnian System - New Interior Models for the Saturnian satellites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Castillo, J. C.; Matson, D. L.; Johnson, T. V.; Lunine, J. I.; McCord, T. B.; Sotin, C.; Thomas, P. C.; Turtle, E. B.</p> <p>2005-12-01</p> <p>Recent study of Iapetus' spin rate evolution highlights the need to form this satellite between between 1.0+/- 0.2 to 1.6+/- 0.4 My after the production of Calcium-Aluminum Inclusions (CAIs). We study the implications of this time constraint on the thermal evolution of other "icy" Saturnian satellites, assuming that they formed at the same time as Iapetus and from the same rocky material in proportion to their densities. Heat provided by <span class="hlt">26</span><span class="hlt">Al</span> decay contributes to partial to full melting and thus differentiation of all Saturn's medium-sized satellites, except Tethys. We also consider the effect of silicate hydration on the internal and geological evolution of these satellites. These results are compared with classical models (that do not include short-lived radiogenic species), in the light of the observational constraints available for these satellites. Including <span class="hlt">26</span><span class="hlt">Al</span> decay in the heat budget of the satellites allows to explain the observation of geological activity in silicate-poor satellites such as Tethys. We note that in Enceladus and Titan conditions might have been such that the boiling point of water was reached and water might have been lost very early in the history of these satellites. This opens the door to some explanation for the variations in density within the Saturnian system. Part of this work was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract to NASA.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25459713','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25459713"><span id="translatedtitle">Vibrations and reorientations of NH3 molecules in [Mn(NH3)6](ClO4)2 studied by infrared spectroscopy and theoretical (DFT) calculations.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hetmańczyk, Joanna; Hetmańczyk, Łukasz; Migdał-Mikuli, Anna; Mikuli, Edward</p> <p>2015-02-01</p> <p>The vibrational and reorientational motions of NH3 ligands and ClO4(-) anions were investigated by Fourier transform middle-infrared spectroscopy (FT-IR) in the high- and low-temperature phases of [Mn(NH3)6](ClO4)2. The temperature dependencies of full width at half maximum (FWHM) of the infrared bands at: 591 and 3385cm(-1), associated with: ρr(NH3) and νas(N-H) modes, respectively, indicate that there exist fast (correlation times τR≈10(-12)-10(-13)s) reorientational motions of NH3 ligands, with a mean values of activation energies: 7.8 and 4.5kJmol(-1), in the phase I and II, respectively. These reorientational motions of NH3 ligands are only slightly disturbed in the phase transition region and do not significantly contribute to the phase transition mechanism. Fourier transform far-infrared and middle-infrared spectra with decreasing of temperature indicated characteristic changes at the vicinity of PT at TC(c)=137.6K (on cooling), which suggested lowering of the crystal structure symmetry. Infrared spectra of [Mn(NH3)6](ClO4)2 were recorded and interpreted by comparison with respective theoretical spectra calculated using DFT method (B3LYP functional, LANL2DZ ECP basis set (on Mn atom) and 6-311+G(d,p) basis set (on H, N, Cl, O atoms) for the isolated equilibrium two models (Model 1 - separate isolated [Mn(NH3)6](2+) cation and ClO4(-) anion and Model 2 - [Mn(NH3)6(ClO4)2] complex system). Calculated optical spectra show a good agreement with the experimental infrared spectra (FT-FIR and FT-MIR) for the both models. PMID:25459713</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li class="active"><span>7</span></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_7 --> <div id="page_8" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active"><span>8</span></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="141"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18389270','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18389270"><span id="translatedtitle">Intercomparison study on (152)Eu gamma ray and (<span class="hlt">36</span>)<span class="hlt">Cl</span> AMS measurements for development of the new Hiroshima-Nagasaki Atomic Bomb Dosimetry System 2002 (DS02).</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hoshi, M; Endo, S; Tanaka, K; Ishikawa, M; Straume, T; Komura, K; Rühm, W; Nolte, E; Huber, T; Nagashima, Y; Seki, R; Sasa, K; Sueki, K; Fukushima, H; Egbert, S D; Imanaka, T</p> <p>2008-07-01</p> <p>In the process of developing a new dosimetry system for atomic bomb survivors in Hiroshima and Nagasaki (DS02), an intercomparison study between (152)Eu and (<span class="hlt">36</span>)<span class="hlt">Cl</span> measurements was proposed, to reconcile the discrepancy previously observed in the Hiroshima data between measurements and calculations of thermal neutron activation products. Nine granite samples, exposed to the atomic-bomb radiation in Hiroshima within 1,200 m of the hypocenter, as well as mixed standard solutions containing known amounts of europium and chlorine that were neutron-activated by a (252)Cf source, were used for the intercomparison. Gamma-ray spectrometry for (152)Eu was carried out with ultra low-background Ge detectors at the Ogoya Underground Laboratory, Kanazawa University, while three laboratories participated in the (<span class="hlt">36</span>)<span class="hlt">Cl</span> measurement using accelerator mass spectrometry (AMS): The Technical University of Munich, Germany, the Lawrence Livermore National Laboratory, USA and the University of Tsukuba, Japan. Measured values for the mixed standard solutions showed good agreement among the participant laboratories. They also agreed well with activation calculations, using the neutron fluences monitored during the (252)Cf irradiation, and the corresponding activation cross-sections taken from the JENDL-3.3 library. The measured-to-calculated ratios obtained were 1.02 for (152)Eu and 0.91-1.02 for (<span class="hlt">36</span>)<span class="hlt">Cl</span>, respectively. Similarly, the results of the granite intercomparison indicated good agreement with the DS02 calculation for these samples. An average measured-to-calculated ratio of 0.98 was obtained for all granite intercomparison measurements. The so-called neutron discrepancy that was previously observed and that which included increasing measured-to-calculated ratios for thermal neutron activation products for increasing distances beyond 1,000 m from the hypocenter was not seen in the results of the intercomparison study. The previously claimed discrepancy could be explained by</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AcSpA.136.1515H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AcSpA.136.1515H"><span id="translatedtitle">Vibrations and reorientations of NH3 molecules in [Mn(NH3)6](ClO4)2 studied by infrared spectroscopy and theoretical (DFT) calculations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hetmańczyk, Joanna; Hetmańczyk, Łukasz; Migdał-Mikuli, Anna; Mikuli, Edward</p> <p>2015-02-01</p> <p>The vibrational and reorientational motions of NH3 ligands and ClO4- anions were investigated by Fourier transform middle-infrared spectroscopy (FT-IR) in the high- and low-temperature phases of [Mn(NH3)6](ClO4)2. The temperature dependencies of full width at half maximum (FWHM) of the infrared bands at: 591 and 3385 cm-1, associated with: ρr(NH3) and νas(N-H) modes, respectively, indicate that there exist fast (correlation times τR ≈ 10-12-10-13 s) reorientational motions of NH3 ligands, with a mean values of activation energies: 7.8 and 4.5 kJ mol-1, in the phase I and II, respectively. These reorientational motions of NH3 ligands are only slightly disturbed in the phase transition region and do not significantly contribute to the phase transition mechanism. Fourier transform far-infrared and middle-infrared spectra with decreasing of temperature indicated characteristic changes at the vicinity of PT at TCc = 137.6 K (on cooling), which suggested lowering of the crystal structure symmetry. Infrared spectra of [Mn(NH3)6](ClO4)2 were recorded and interpreted by comparison with respective theoretical spectra calculated using DFT method (B3LYP functional, LANL2DZ ECP basis set (on Mn atom) and 6-311 + G(d,p) basis set (on H, N, Cl, O atoms) for the isolated equilibrium two models (Model 1 - separate isolated [Mn(NH3)6]2+ cation and ClO4- anion and Model 2 - [Mn(NH3)6(ClO4)2] complex system). Calculated optical spectra show a good agreement with the experimental infrared spectra (FT-FIR and FT-MIR) for the both models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JNuM..464..405T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JNuM..464..405T"><span id="translatedtitle">Ion irradiation of 37Cl implanted nuclear graphite: Effect of the energy deposition on the chlorine behavior and consequences for the mobility of <span class="hlt">36</span><span class="hlt">Cl</span> in irradiated graphite</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Toulhoat, N.; Moncoffre, N.; Bérerd, N.; Pipon, Y.; Blondel, A.; Galy, N.; Sainsot, P.; Rouzaud, J.-N.; Deldicque, D.</p> <p>2015-09-01</p> <p>Graphite is used in many types of nuclear reactors due to its ability to slow down fast neutrons without capturing them. Whatever the reactor design, the irradiated graphite waste management has to be faced sooner or later regarding the production of long lived or dose determining radioactive species such as 14C, 3H or <span class="hlt">36</span><span class="hlt">Cl</span>. The first carbon dioxide cooled, graphite moderated nuclear reactors resulted in a huge quantity of irradiated graphite waste for which the management needs a previous assessment of the radioactive inventory and the radionuclide's location and speciation. As the detection limits of usual spectroscopic methods are generally not adequate to detect the low concentration levels (<1 ppm) of the radionuclides, we used an indirect approach based on the implantation of 37Cl, to simulate the presence of <span class="hlt">36</span><span class="hlt">Cl</span>. Our previous studies show that temperature is one of the main factors to be considered regarding the structural evolution of nuclear graphite and chlorine mobility during reactor operation. However, thermal release of chlorine cannot be solely responsible for the depletion of the <span class="hlt">36</span><span class="hlt">Cl</span> inventory. We propose in this paper to study the impact of irradiation and its synergetic effects with temperature on chlorine release. Indeed, the collision of the impinging neutrons with the graphite matrix carbon atoms induces mainly ballistic collisions. However, a small part of the recoil carbon atom energy is also transferred to the lattice through electronic excitation. This paper aims at elucidating the effects of the different irradiation regimes (ballistic and electronic) using ion irradiation, on the mobility of implanted 37Cl, taking into account the initial disorder level of the nuclear graphite.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.2151L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.2151L"><span id="translatedtitle">Multi-isotope comparison of 3He, 21Ne, and <span class="hlt">36</span><span class="hlt">Cl</span> moraine ages from the high-altitude central Puna Plateau, NW Argentina (24°S)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Luna, Lisa; Bookhagen, Bodo; Niedermann, Samuel; Merchel, Silke; Rugel, Georg; Scharf, Andreas; Strecker, Manfred</p> <p>2016-04-01</p> <p>Glacial deposits on the high-altitude, arid Puna Plateau of northwestern Argentina document past changes in climate, but the associated geomorphic features have never been directly dated. The plateau is situated in the "Arid Diagonal," the hyper-arid transition zone between the Westerlies precipitation dominated southern Andes, and the South American Summer Monsoon controlled central Andes. Despite the climatically critical position of the Puna Plateau, paleoclimate data for the region is extremely sparse. This study provides direct age control of glacial moraine deposits from the central Puna Plateau (24°S) at elevations of 4500-5000 m through cosmogenic surface exposure dating. The volcanic lithologies of the deposits additionally allow for comparison of production rates from multiple cosmogenic isotope systems at low latitude and high elevation. Moraine boulders were dated using cosmogenic 3He from pyroxene, 21Ne from quartz, and <span class="hlt">36</span><span class="hlt">Cl</span> from feldspars. Preliminary data suggests that the most extensive glaciation occurred more than 80 ka ago, and that an additional prominent advance occurred at ~39 ka. In addition, comparison of isotope production ratios from low latitude and high elevation will contribute to better constrained production rates, particularly for <span class="hlt">36</span><span class="hlt">Cl</span>, for which global production rate estimates are highly variable. This study documents Quaternary climate changes on the Puna Plateau, while at the same time improving production rate agreement between multiple cosmogenic isotope systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015A%26A...578A.113K&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015A%26A...578A.113K&link_type=ABSTRACT"><span id="translatedtitle"><span class="hlt">26</span><span class="hlt">Al</span> kinematics: superbubbles following the spiral arms?. Constraints from the statistics of star clusters and HI supershells</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Krause, Martin G. H.; Diehl, Roland; Bagetakos, Yiannis; Brinks, Elias; Burkert, Andreas; Gerhard, Ortwin; Greiner, Jochen; Kretschmer, Karsten; Siegert, Thomas</p> <p>2015-06-01</p> <p>Context. High-energy resolution spectroscopy of the 1.8 MeV radioactive decay line of <span class="hlt">26</span><span class="hlt">Al</span> with the SPI instrument onboard the INTEGRAL satellite has recently revealed that diffuse <span class="hlt">26</span><span class="hlt">Al</span> has higher velocities than other components of the interstellar medium in the Milky Way. <span class="hlt">26</span><span class="hlt">Al</span> shows Galactic rotation in the same sense as the stars and other gas tracers, but reaches excess velocities of up to 300 km s-1. Aims: We investigate whether this result can be understood in the context of superbubbles, taking into account the statistics of young star clusters and HI supershells as well as the association of young star clusters with spiral arms. Methods: We derived energy output and <span class="hlt">26</span><span class="hlt">Al</span> mass of star clusters as a function of the cluster mass by population synthesis from stellar evolutionary tracks of massive stars. Using the limiting cases of weakly and strongly dissipative superbubble expansion, we linked this to the size distribution of HI supershells and assessed the properties of possible <span class="hlt">26</span><span class="hlt">Al</span>-carrying superbubbles. Results: <span class="hlt">26</span><span class="hlt">Al</span> is produced by star clusters of all masses above ≈200 M⊙, is roughly equally contributed over a logarithmic star cluster mass scale and strongly linked to the injection of feedback energy. The observed superbubble size distribution cannot be related to the star cluster mass function in a straightforward manner. To avoid the added volume of all superbubbles exceeding the volume of the Milky Way, individual superbubbles have to merge frequently. If any two superbubbles merge, or if <span class="hlt">26</span><span class="hlt">Al</span> is injected off-centre into a larger HI supershell, we expect the hot <span class="hlt">26</span><span class="hlt">Al</span>-carrying gas to obtain velocities of the order of the typical sound speed in superbubbles, ≈300 km s-1 before decay. For star formation coordinated by the spiral arm pattern which, inside co-rotation, is overtaken by the faster moving stars and gas, outflows from spiral arm star clusters would preferentially flow into the cavities that are inflated by previous star formation</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015NIMPB.361..346F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015NIMPB.361..346F"><span id="translatedtitle">Towards improvement of aluminium assay in quartz for in situ cosmogenic <span class="hlt">26</span><span class="hlt">Al</span> analysis at ANSTO</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fujioka, Toshiyuki; Fink, David; Mifsud, Charles</p> <p>2015-10-01</p> <p>Accuracy and precision in the measurement of natural aluminium abundances in quartz can affect the reliability of <span class="hlt">26</span><span class="hlt">Al</span> exposure dating and <span class="hlt">26</span><span class="hlt">Al</span>/10Be burial dating. At ANSTO, aliquots extracted from the HF solutions of dissolved quartz are treated in our laboratory, whereas ICP-OES analysis is performed at a commercial laboratory. The long-term inter-run reproducibility of our in-house standards show a limiting precision in Al measurements of 3-4% (1σ), which is lower than the claimed precision of Al analysis by ICP-OES. This indicates that unaccounted random errors are incorporated during our aliquot preparation. In this study, we performed several controlled tests to investigate effects of possible inconsistencies and variances during our aliquot preparation procedure. The results indicate that our procedure is robust against any subtle change in the preparation procedure, e.g., fuming temperatures, fuming reagents, and drying conditions. We found that the density of the solutions dispatched for ICP analysis is occasionally variable due to the presence of residual fuming reagents in the solution. A comparison of the results between the calibration curve and standard addition methods show that the former results are consistently lower than the latter by up to ∼14%. Similar offsets have been reported by previous studies. The reason for these discrepancies is mostly likely matrix effect, which is not accounted for by the calibration curve method. Further tests by varying matrix with impurities such as HF, HClO4, H2SO4 and Si identified that Si could cause lower offset in Al measurements; however, our ICP solutions are confirmed to be free from Si and the cause of matrix effect remains to be investigated. Hence, care must be taken for the measurement of Al concentrations in quartz by ICP-OES, either by ensuring that matrix effect is fully accounted for or by routinely employing standard additions when required.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/pages/biblio/1255183-feasibility-isobaric-suppression-via-post-accelerator-foil-stripping-measurement-feasibility-isobaric-suppression-via-post-accelerator-foil-stripping-measurement','SCIGOV-DOEP'); return false;" href="http://www.osti.gov/pages/biblio/1255183-feasibility-isobaric-suppression-via-post-accelerator-foil-stripping-measurement-feasibility-isobaric-suppression-via-post-accelerator-foil-stripping-measurement"><span id="translatedtitle">The feasibility of isobaric suppression of 26Mg via post-accelerator foil stripping for the measurement of <span class="hlt">26</span><span class="hlt">Al</span> [The feasibility of isobaric suppression of 26Mg via post-accelerator foil stripping for the measurement of <span class="hlt">26</span><span class="hlt">Al</span>.</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Tumey, Scott J.; Brown, Thomas A.; Finkel, Robert C.; Rood, Dylan H.</p> <p>2012-09-13</p> <p>Most accelerator mass spectrometry measurements of <span class="hlt">26</span><span class="hlt">Al</span> utilize the Al- ion despite lower source currents compared with AlO- since the stable isobar 26Mg does not form elemental negative ions. A gas-filled magnet allows sufficient suppression of 26Mg thus enabling the use of the more intense <span class="hlt">26</span><span class="hlt">Al</span>O- ion. However, most AMS systems do not include a gas-filled magnet. We therefore explored the feasibility of suppressing 26Mg by using a post-accelerator stripping foil. With this approach, combined with the use of alternative cathode matrices, we were able to suppress 26Mg by a factor of twenty. This suppression was insufficient to enable themore » use of <span class="hlt">26</span><span class="hlt">Al</span>O-, however further refinement of our system may permit its use in the future.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/835912','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/835912"><span id="translatedtitle">Activation Measurements for Thermal Neutrons, U.S. Measurements of <span class="hlt">36</span><span class="hlt">Cl</span> in Mineral Samples from Hiroshima and Nagasaki; and Measurement of 63 Ni in Copper Samples From Hiroshima by Accelerator Mass Spectrometry</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Tore Straume; Alfredo A. Marchetti; Stephen D. Egbert; James A. Roberts; Ping Men; Shoichiro Fujita; Kiyoshi Shizuma; Masaharu Hoshi; G. Rugel; W. Ruhm; G. Korschinek; J. E. McAninch; K. L. Carroll; T. Faestermann; K. Knie; R. E. Martinelli; A. Wallner; C. Wallner</p> <p>2005-01-14</p> <p>The present paper presents the {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> measurement effort in the US. A large number of {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> measurements have been made in both granite and concrete samples obtained from various locations and distances in Hiroshima and Nagasaki. These measurements employed accelerator mass spectrometry (AMS) to quantify the number of atoms of {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> per atom of total Cl in the sample. Results from these measurements are presented here and discussed in the context of the DS02 dosimetry reevaluation effort for Hiroshima and Nagasaki atomic-bomb survivors. The production of {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> by bomb neutrons in mineral samples from Hiroshima and Nagasaki was primarily via the reaction {sup 35}Cl(n,{gamma}){sup <span class="hlt">36</span>}<span class="hlt">Cl</span>. This reaction has a substantial thermal neutron cross-section (43.6 b at 0.025 eV) and the product has a long half-life (301,000 y). hence, it is well suited for neutron-activation detection in Hiroshima and Nagasaki using AMS more than 50 years after the bombings. A less important reaction for bomb neutrons, {sup 39}K(n,{alpha}){sup <span class="hlt">36</span>}<span class="hlt">Cl</span>, typically produces less than 10% of the {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> in mineral samples such as granite and concrete, which contain {approx} 2% potassium. In 1988, only a year after the publication of the DS86 final report (Roesch 1987), it was demonstrated experimentally that {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> measured using AMS should be able to detect the thermal neutron fluences at the large distances most relevant to the A-bomb survivor dosimetry. Subsequent measurements in mineral samples from both Hiroshima and Nagasaki validated the experimental findings. The potential utility of {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> as a thermal neutron detector in Hiroshima was first presented by Haberstock et al. who employed the Munich AMS facility to measure {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>/Cl ratios in a gravestone from near the hypocenter. That work subsequently resulted in an expanded {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> effort in Germany that paralleled the US work. More recently, there have also been {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> measurements made by a Japanese</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70029102','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70029102"><span id="translatedtitle">Dating Plio-Pleistocene glacial sediments using the cosmic-ray-produced radionuclides 10Be and <span class="hlt">26</span><span class="hlt">Al</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Balco, G.; Stone, J.O.H.; Jennings, C.</p> <p>2005-01-01</p> <p>We use the cosmic-ray-produced radionuclides <span class="hlt">26</span><span class="hlt">Al</span> and 10Be to date Plio-Pleistocene glacial sediment sequences. These two nuclides are produced in quartz at a fixed ratio, but have different decay constants. If a sample is exposed at the surface for a time and then buried by overburden and thus removed from the cosmic-ray flux, the <span class="hlt">26</span><span class="hlt">Al</span>/10Be ratio is related to the duration of burial. We first attempted to date pre-Wisconsinan tills by measuring <span class="hlt">26</span><span class="hlt">Al</span> and 10Be in fluvial sediments beneath them and applying the method of "burial dating," which previous authors have used to date river sediment carried into caves. This method, however, requires simplifying assumptions about the <span class="hlt">26</span><span class="hlt">Al</span> and 10Be concentrations in the sediment at the time of burial. We show that these assumptions are not valid for river sediment in glaciated regions. <span class="hlt">26</span><span class="hlt">Al</span> and 10Be analyses of such sediment do not provide accurate ages for these tills, although they do yield limiting ages in some cases. We overcome this difficulty by instead measuring <span class="hlt">26</span><span class="hlt">Al</span> and 10Be in quartz from paleosols that are buried by tills. We use a more general mathematical approach to determine the initial nuclide concentrations in the paleosol at the time it was buried, as well as the duration of burial. This technique provides a widely applicable improvement on other means of dating Plio-Pleistocene terrestrial glacial sediments, as well as a framework for applying cosmogenic-nuclide dating techniques in complicated stratigraphic settings. We apply it to pre-Wisconsinan glacial sediment sequences in southwest Minnesota and eastern South Dakota. Pre-Wisconsinan tills underlying the Minnesota River Valley were deposited 0.5 to 1.5 Ma, and tills beneath the Prairie Coteau in eastern South Dakota and adjacent Minnesota were deposited 1 to 2 Ma.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/756734','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/756734"><span id="translatedtitle">Update on terrestrial ages of Antarctic meteorites</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Welten, K C; Nishiizumi, K; Caffee, M W</p> <p>2000-01-14</p> <p>Terrestrial ages of Antarctic meteorites are one of the few parameters that will help us to understand the meteorite concentration mechanism on blue-ice fields. Traditionally, terrestrial ages were determined on the basis of {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> in the metal phase, which has an uncertainty of about 70 ky. For young meteorites (< 40 ky), the terrestrial age is usually and most accurately determined using {sup 14}C in the stone phase. In recent years two methods have been developed which are independent of shielding effects, the {sup 10}Be-{sup <span class="hlt">36</span>}<span class="hlt">Cl</span>/{sup 10}Be method and the {sup <span class="hlt">41</span>}<span class="hlt">Ca</span>/{sup <span class="hlt">36</span>}<span class="hlt">Cl</span> method. These methods have reduced the typical uncertainties in terrestrial ages by a factor of 2, to about 30 ky. The {sup 10}Be-{sup <span class="hlt">36</span>}<span class="hlt">Cl</span>/{sup 10}Be method is quite dependent on the exposure age, which is unknown for most Antarctic meteorites. The authors therefore also attempt to use the relation between {sup <span class="hlt">26</span>}<span class="hlt">Al</span> and {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>/{sup <span class="hlt">26</span>}<span class="hlt">Al</span> to derive a terrestrial age less dependent on the exposure age. The authors have measured the concentrations of cosmogenic {sup 10}Be, {sup <span class="hlt">26</span>}<span class="hlt">Al</span> and {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> in the metal phase of {approximately} 70 Antarctic meteorites, from more than 10 different ice-fields, including many new ones. They then discuss the trends in terrestrial ages of meteorites from different ice-fields.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23811127','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23811127"><span id="translatedtitle">Translocation of (125)I, (75)Se and (<span class="hlt">36</span>)<span class="hlt">Cl</span> to edible parts of radish, potato and green bean following wet foliar contamination under field conditions.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Henner, P; Hurtevent, P; Thiry, Y; Levchuk, S; Yoschenko, V; Kashparov, V</p> <p>2013-10-01</p> <p>Specific translocation factor values (ftr) for (129)I, (79)Se and (<span class="hlt">36</span>)<span class="hlt">Cl</span> following foliar transfer are still missing from the IAEA reference databases. The translocation of the short-lived isotopes, (125)I, (75)Se, and (<span class="hlt">36</span>)<span class="hlt">Cl</span>, to radish, potato and green bean edible parts was measured under field conditions following acute and chronic wet foliar contamination at various plant growth stages in the absence of leaching caused by rain. The translocation factors obtained for (125)I ranged from 0.8 to 2.6% for radish, from 0.1 to 2.3% for potato and from 0.1 to 2.6% for bean. The translocation factors obtained for (75)Se ranged from 6.3 to 21% for radish, from 1.6 to 32.6% for potato and from 7.7 to 22.8% for bean (values similar to Cs or even higher). The translocation factors obtained for (<span class="hlt">36</span>)<span class="hlt">Cl</span> were close to those for (75)Se and ranged from 4.3 to 28.8% for radish, from 0.5 to 31.5% for potato and from 4.3 to 16.3% for bean. Iodide showed the lowest apparent mobility because of its preferential fixation in or on the leaves and a significant amount was probably volatilized. Selenite internal transfer was significant and possibly followed the sulfur metabolic pathway. Chloride was very mobile and quickly diffused throughout the plant. The translocation factors varied with the growth stage and depended on the development state of the edible tissue and its associated sink strength for nutrients and assimilates. For radish, translocation was high during the early vegetative stages. For potato, wheat and bean, a major peak in translocation was seen during the flowering growth stage and the concomitant growth of potato tubers. An additive effect of successive contamination events on translocated elements was shown in radish but not in bean and potato. The highest translocation value obtained for an acute contamination event was shown to be an adequate, conservative indicator of chronic contamination in absence of specific values. Due to the absence of rain leaching during</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1814251Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1814251Y"><span id="translatedtitle">Deriving earthquake history of the Knidos Fault Zone, SW Turkey, using cosmogenic <span class="hlt">36</span><span class="hlt">Cl</span> surface exposure dating of the fault scarp.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yildirim, Cengiz; Ersen Aksoy, Murat; Akif Sarikaya, Mehmet; Tuysuz, Okan; Genc, S. Can; Ertekin Doksanalti, Mustafa; Sahin, Sefa; Benedetti, Lucilla; Tesson, Jim; Aster Team</p> <p>2016-04-01</p> <p>Formation of bedrock fault scarps in extensional provinces is a result of large and successive earthquakes that ruptured the surface several times. Extraction of seismic history of such faults is critical to understand the recurrence intervals and the magnitude of paleo-earthquakes and to better constrain the regional seismic hazard. Knidos on the Datca Peninsula (SW Turkey) is one of the largest cities of the antique times and sits on a terraced hill slope formed by en-echelon W-SW oriented normal faults. The Datça Peninsula constitutes the southern boundary of the Gulf of Gökova, one of the largest grabens developed on the southernmost part of the Western Anatolian Extensional Province. Our investigation relies on cosmogenic <span class="hlt">36</span><span class="hlt">Cl</span> surface exposure dating of limestone faults scarps. This method is a powerful tool to reconstruct the seismic history of normal faults (e.g. Schlagenhauf et al 2010, Benedetti et al. 2013). We focus on one of the most prominent fault scarp (hereinafter Mezarlık Fault) of the Knidos fault zone cutting through the antique Knidos city. We collected 128 pieces of tablet size (10x20cm) 3-cm thick samples along the fault dip and opened 4 conventional paleoseismic trenches at the base of the fault scarp. Our <span class="hlt">36</span><span class="hlt">Cl</span> concentration profile indicates that 3 to 4 seismic events ruptured the Mezarlık Fault since Last Glacial Maximum (LGM). The results from the paleoseismic trenching are also compatible with <span class="hlt">36</span><span class="hlt">Cl</span> results, indicating 3 or 4 seismic events that disturbed the colluvium deposited at the base of the scarp. Here we will present implications for the seismic history and the derived slip-rate of the Mezarlık Fault based on those results. This project is supported by The Scientific and Technological Research Council of Turkey (TUBITAK, Grant number: 113Y436) and it was conducted with the Decision of the Council of Ministers with No. 2013/5387 on the date 30.09.2013 and was done with the permission of Knidos Presidency of excavation in</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001M%26PS...36..963L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001M%26PS...36..963L"><span id="translatedtitle">Cosmic-ray production rates of He-, Ne- and Ar-isotopes in H-chondrites based on <span class="hlt">36</span><span class="hlt">Cl</span>-36Ar-ages</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Leya, I.; Graf, Th.; Nishiizumi, K.; Wieler, R.</p> <p>2001-07-01</p> <p>We present the concentrations and isotopic compositions of He, Ne, and Ar for non-magnetic fractions and bulk samples of 17 H-chondrites which were recently investigated for their <span class="hlt">36</span><span class="hlt">Cl</span>-36Ar cosmic-ray exposure ages (Graf et al., 2001). All selected meteorites are observed falls with cosmic-ray exposure ages close to the 7 Ma peak. The rare gas data are consistent with 10Be and <span class="hlt">36</span><span class="hlt">Cl</span> production rates in the metal phase. Remarkably, only one out of the 17 H-chondrites, Bath, shows clear indications for a complex exposure history. Based on rare gas concentrations and <span class="hlt">36</span><span class="hlt">Cl</span>-36Ar exposure ages, 21Ne production rates as a function of 22Ne/21Ne and a mean 38Ar production rate are determined. The results confirm model calculations which predict that the relationship between 21Ne production rates and 22Ne/21Ne is ambiguous for high shielding. Besides the mean 38Ar production rate we also give production rate ratios P(38Ar from Ca) / P(38Ar from Fe). They vary between 10 and 77, showing no significant correlation with 38Ar-concentrations or 22Ne/21Ne. By investigating the metal-separates, Graf et al. (2001) found significant 3He deficits for six out of the 17 meteorites. For the non-magnetic fractions and bulk samples investigated here the data points in a 3He/21Ne versus 22Ne/21Ne diagram plot in the area defined by most of the H-chondrites. This means that 3He deficits in the metal phase are much more pronounced than in silicate minerals and we will argue that 3H diffusive losses in meteorites should be the rule rather than the exception. The 21Ne exposure ages, calculated on the basis of modeled 21Ne production rates, confirm the assumption by Graf et al. (2001) that the H5-chondrites with low 3He/38Ar in the metal formed in a separate event than those with normal 3He/38Ar ratios. The data can best be interpreted by assuming that the prominent 7 Ma exposure age peak of the H-chondrites is due to at least two events about 7.0 and 7.6 Ma ago.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004E%26PSL.225..163P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004E%26PSL.225..163P"><span id="translatedtitle">Slip history of the Magnola fault (Apennines, Central Italy) from <span class="hlt">36</span><span class="hlt">Cl</span> surface exposure dating: evidence for strong earthquakes over the Holocene</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Palumbo, Luigi; Benedetti, Lucilla; Bourlès, Didier; Cinque, Aldo; Finkel, Robert</p> <p>2004-08-01</p> <p>To better understand the mechanics of deformation in the Mediterranean and the role that the convergence between Africa and Europe plays, it is necessary to know the deformation field at different time scales. Here we use in situ <span class="hlt">36</span><span class="hlt">Cl</span> surface exposure dating of exposed bedrock fault scarps to determine earthquake time-slip histories and to quantify slip rates over the last several thousand years. This information allows us to delineate the seismic history of normal faulting within the Mediterranean area over that time period. We have studied the limestone scarp produced by the Magnola fault in the Central Apennines, Italy. The Magnola fault, in the Fucino area, is an active, 15-km long, normal fault striking WNW and dipping SSW. The range front morphology, characterised by steep triangular facets separated by V-shaped valleys and wine-glass canyons, suggests that the Magnola fault has been active for at least the last several hundred thousand years. At the base of the facets, the fault cuts limestone bedrock to produce a well-preserved normal fault scarp 10 to 12 m high. The distribution of <span class="hlt">36</span><span class="hlt">Cl</span> concentration versus the height along that scarp is best explained by a minimum of five and a maximum of seven successive earthquake exhumations, with slips varying between 1.5 and 3 m. An age of ˜5 ka at the base of the scarp and of ˜12 ka at the top yields a slip rate of ˜0.8 mm/year. The absence of any event on this fault during the last 5000 years suggests either that a future event is imminent on the Magnola fault or that the fault has entered a quiescent period with much longer recurrence time. Our study confirms that the Magnola fault scarp is post-glacial and supports the hypothesis that similar scarps in the Mediterranean are also post-glacial.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25706272','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25706272"><span id="translatedtitle"><span class="hlt">26</span><span class="hlt">Al</span>/10Be burial dating of Xujiayao-Houjiayao site in Nihewan Basin, northern China.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tu, Hua; Shen, Guanjun; Li, Haixu; Xie, Fei; Granger, Darryl E</p> <p>2015-01-01</p> <p>The Xujiayao-Houjiayao site in Nihewan Basin is among the most important Paleolithic sites in China for having provided a rich collection of hominin and mammalian fossils and lithic artifacts. Based on biostratigraphical correlation and exploratory results from a variety of dating methods, the site has been widely accepted as early Upper Pleistocene in time. However, more recent paleomagnetic analyses assigned a much older age of ∼500 ka (thousand years). This paper reports the application of <span class="hlt">26</span><span class="hlt">Al</span>/10Be burial dating as an independent check. Two quartz samples from a lower cultural horizon give a weighted mean age of 0.24 ± 0.05 Ma (million years, 1σ). The site is thus younger than 340 ka at 95% confidence, which is at variance with the previous paleomagnetic results. On the other hand, our result suggests an age of older than 140 ka for the site's lower cultural deposits, which is consistent with recent post-infrared infrared stimulated luminescence (pIR-IRSL) dating at 160-220 ka.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19279636','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19279636"><span id="translatedtitle">Age of Zhoukoudian Homo erectus determined with (<span class="hlt">26</span>)<span class="hlt">Al</span>/(10)Be burial dating.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Shen, Guanjun; Gao, Xing; Gao, Bin; Granger, Darryl E</p> <p>2009-03-12</p> <p>The age of Zhoukoudian Homo erectus, commonly known as 'Peking Man', has long been pursued, but has remained problematic owing to the lack of suitable dating methods. Here we report cosmogenic (<span class="hlt">26</span>)<span class="hlt">Al</span>/(10)Be burial dating of quartz sediments and artefacts from the lower strata of Locality 1 in the southwestern suburb of Beijing, China, where early representatives of Zhoukoudian Homo erectus were discovered. This study marks the first radioisotopic dating of any early hominin site in China beyond the range of mass spectrometric U-series dating. The weighted mean of six meaningful age measurements, 0.77 +/- 0.08 million years (Myr, mean +/- s.e.m.), provides the best age estimate for lower cultural layers 7-10. Together with previously reported U-series dating of speleothem calcite and palaeomagnetic stratigraphy, as well as sedimentological considerations, these layers may be further correlated to S6-S7 in Chinese loess stratigraphy or marine isotope stages (MIS) 17-19, in the range of approximately 0.68 to 0.78 Myr ago. These ages are substantially older than previously supposed and may imply early hominin's presence at the site in northern China through a relatively mild glacial period corresponding to MIS 18.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4338100','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4338100"><span id="translatedtitle"><span class="hlt">26</span><span class="hlt">Al</span>/10Be Burial Dating of Xujiayao-Houjiayao Site in Nihewan Basin, Northern China</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Tu, Hua; Shen, Guanjun; Li, Haixu; Xie, Fei; Granger, Darryl E.</p> <p>2015-01-01</p> <p>The Xujiayao-Houjiayao site in Nihewan Basin is among the most important Paleolithic sites in China for having provided a rich collection of hominin and mammalian fossils and lithic artifacts. Based on biostratigraphical correlation and exploratory results from a variety of dating methods, the site has been widely accepted as early Upper Pleistocene in time. However, more recent paleomagnetic analyses assigned a much older age of ∼500 ka (thousand years). This paper reports the application of <span class="hlt">26</span><span class="hlt">Al</span>/10Be burial dating as an independent check. Two quartz samples from a lower cultural horizon give a weighted mean age of 0.24 ± 0.05 Ma (million years, 1σ). The site is thus younger than 340 ka at 95% confidence, which is at variance with the previous paleomagnetic results. On the other hand, our result suggests an age of older than 140 ka for the site’s lower cultural deposits, which is consistent with recent post-infrared infrared stimulated luminescence (pIR-IRSL) dating at 160–220 ka. PMID:25706272</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6967766','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6967766"><span id="translatedtitle">Examination of surface exposure age of Antarctic moraines using in situ produced [sup 10]Be and [sup <span class="hlt">26</span>]<span class="hlt">Al</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Brown, E.T.; Edmond, J.M. ); Raisbeck, G.M.; Yiou, F. ); Kurz, M.D.; Brook, E.J. )</p> <p>1991-08-01</p> <p>Concentrations of [sup 10]Be (t[sub 1/2] = 1.5 [times] 10[sup 6]y) and [sup <span class="hlt">26</span>]<span class="hlt">Al</span> (t[sub 1/2] = 0.72 [times] 10[sup 6]y) have been determined by accelerator mass spectrometry (AMS) in a suite of quartz samples taken from sandstone boulders in several moraines in Arena Valley, a dry valley adjacent to the Taylor Glacier in the Quatermain Mountains, Southern Victoria Land, East Antarctica. These isotopes are produced in surficial quartz by cosmic ray spallation of O and Si. The concentrations in these samples ranged from 6.1 [times] 10[sup 5] to 3.0 [times] 10[sup 7] at g[sup [minus]1] for [sup 10]Be and from 9.4 [times] 10[sup 6] to 1.2 [times] 10[sup 8] at g[sup [minus]1] for [sup <span class="hlt">26</span>]<span class="hlt">Al</span>, depending upon the extent of exposure at the surface. Production rates of 17[sub [minus]4][sup +16] at g[sup [minus]1]y[sup [minus]1] for [sup 10]Be and 113[sub [minus]16][sup +54] at g[sup [minus]1]y[sup [minus]1] for [sup <span class="hlt">26</span>]<span class="hlt">Al</span> at 1300 m and 87[degree]S and a [sup <span class="hlt">26</span>]<span class="hlt">Al</span>:[sup 10]Be production ratio of 6.5[sub [minus]1.3][sup +1.3] were calculated from the data. These values correspond to sea-level production rates at high geomagnetic latitude of 6.4 at g[sup [minus]1]y[sup [minus]1] and 41.7 at g[sup [minus]1]y[sup [minus]1] for [sup 10]Be and [sup <span class="hlt">26</span>]<span class="hlt">Al</span>, respectively, consistent with determinations based on [approximately]11 Ky glacially polished surfaces in the Sierra Nevada in California. These production rates imply exposure ages for the various moraines ranging from 50 Ky to 2.5 My, in accordance with other geological evidence. The [sup 10]Be and [sup <span class="hlt">26</span>]<span class="hlt">Al</span> ages of these rocks compare favorably with those found using a similar dating method based on in situ production of [sup 3]He.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012LPI....43.2255K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012LPI....43.2255K"><span id="translatedtitle">Heterogeneous Distribution of ^2^6Al at the Birth of the Solar System: Evidence from Corundum-Bearing Refractory Inclusions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Krot, A. N.; Makide, K.; Nagashima, K.; Huss, G. R.; Hellebrand, E.; Petaev, M. I.</p> <p>2012-03-01</p> <p>Corundum-bearing CAIs recorded heterogeneous distribution of ^2^6Al at the birth of the solar system. We suggest that ^2^6Al was injected into the protosolar molecular cloud core by a wind from a massive star and was later homogenized through the disk.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1814159T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1814159T"><span id="translatedtitle">Toward determining the uncertainties associated with the seismic histories retrieved from in situ <span class="hlt">36</span><span class="hlt">Cl</span> cosmogenic nuclide fault scarp dating: model reappraisal.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tesson, Jim; Benedetti, Lucilla</p> <p>2016-04-01</p> <p>How the past seismic activity of faults has varied over the last 20 ky is a crucial information for seismic hazard assessment and for the understanding of fault-interaction processes. Chlorine 36 in situ produced cosmogenic nuclide is increasingly used to retrieve past earthquakes histories on seismically exhumed limestone normal fault-scarps. Schlagenhauf et al. in 2010 developed a modeling code with a forward approach enabling the test of scenarii generated with a priori constraints (number of events, age and slip of events and pre-exposure time). The main shortcomings of this forward approach were the limited number of testable scenarii and the difficulty to derive the associated uncertainties. We present here a reappraisal methodology with an inverse approach using an optimization algorithm. This modelling approach enables 1-exploring the parameter space (age and slip of events), 2-finding the best scenario without a priori constraints and 3-precisely quantifying the associated uncertainties by determining the range of plausible models. Through a series of synthetic tests, we observed that the algorithm revealed a great capacity to constrain event slips and ages in a short computational time (several hours) with an accuracy that can reach 0.1 ky and 0.5 m for the age and slip of exhumation event, respectively. We also explore the influence of the pre-exposure history (amount of <span class="hlt">36</span><span class="hlt">Cl</span> accumulated when the sampled fault-plane was still buried under the colluvial wedge) and show that it has an important impact on the generated scenarii. This new modeling also allows now to accurately determining this parameter. Finally, the results show that any given [<span class="hlt">36</span><span class="hlt">Cl</span>] profile results in a unique exhumation solution. We then apply this new model to the Magnola fault (Italy) dataset (Schlgenhauf et al. 2011). In agreement the previously published results, our model also results in 3 intense periods of seismic activity. However, the contribution of the pre-exposure history is</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active"><span>8</span></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_8 --> <div id="page_9" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="161"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70030141','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70030141"><span id="translatedtitle">Cosmogenic 10Be and <span class="hlt">36</span><span class="hlt">Cl</span> geochronology of offset alluvial fans along the northern Death Valley fault zone: Implications for transient strain in the eastern California shear zone</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Frankel, K.L.; Brantley, K.S.; Dolan, J.F.; Finkel, R.C.; Klinger, R.E.; Knott, J.R.; Machette, M.N.; Owen, L.A.; Phillips, F.M.; Slate, J.L.; Wernicke, B.P.</p> <p>2007-01-01</p> <p>The northern Death Valley fault zone (NDVFZ) has long been recognized as a major right-lateral strike-slip fault in the eastern California shear zone (ECSZ). However, its geologic slip rate has been difficult to determine. Using high-resolution digital topographic imagery and terrestrial cosmogenic nuclide dating, we present the first geochronologically determined slip rate for the NDVFZ. Our study focuses on the Red Wall Canyon alluvial fan, which exposes clean dextral offsets of seven channels. Analysis of airborne laser swath mapping data indicates ???297 ?? 9 m of right-lateral displacement on the fault system since the late Pleistocene. In situ terrestrial cosmogenic 10Be and 36C1 geochronology was used to date the Red Wall Canyon fan and a second, correlative fan also cut by the fault. Beryllium 10 dates from large cobbles and boulders provide a maximum age of 70 +22/-20 ka for the offset landforms. The minimum age of the alluvial fan deposits based on <span class="hlt">36</span><span class="hlt">Cl</span> depth profiles is 63 ?? 8 ka. Combining the offset measurement with the cosmogenic 10Be date yields a geologic fault slip rate of 4.2 +1.9/-1.1 mm yr-1, whereas the <span class="hlt">36</span><span class="hlt">Cl</span> data indicate 4.7 +0.9/-0.6 mm yr-1 of slip. Summing these slip rates with known rates on the Owens Valley, Hunter Mountain, and Stateline faults at similar latitudes suggests a total geologic slip rate across the northern ECSZ of ???8.5 to 10 mm yr-1. This rate is commensurate with the overall geodetic rate and implies that the apparent discrepancy between geologic and geodetic data observed in the Mojave section of the ECSZ does not extend north of the Garlock fault. Although the overall geodetic rates are similar, the best estimates based on geology predict higher strain rates in the eastern part of the ECSZ than to the west, whereas the observed geodetic strain is relatively constant. Copyright 2007 by the American Geophysical Union.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFM.T43D..05S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFM.T43D..05S"><span id="translatedtitle">Three time scales of earthquake clustering inferred from in-situ <span class="hlt">36</span><span class="hlt">Cl</span> cosmogenic dating on the Velino-Magnola fault (Central Italy)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schlagenhauf, A.; Manighetti, I.; Benedetti, L.; Gaudemer, Y.; Malavieille, J.; Finkel, R. C.; Pou, K.</p> <p>2010-12-01</p> <p>Using in-situ <span class="hlt">36</span><span class="hlt">Cl</span> cosmogenic exposure dating, we determine the earthquake slip release pattern over the last ~ 14 kyrs along one of the major active normal fault systems in Central Italy. The ~ 40 km-long Velino-Magnola fault (VMF) is located ~ 20 km SW from the epicenter of the devastating April 2009 l’Aquila earthquake. We sampled the VMF at five well-separated sites along its length, and modeled the <span class="hlt">36</span><span class="hlt">Cl</span> concentrations measured in the 400 samples (Schlagenhauf et al. 2010). We find that the fault has broken in large earthquakes which clustered at three different time scales -monthly, centennial and millennial. More precisely, the fault sustained phases of intense seismic activity, separated by ~ 3 kyr-long periods of relative quiescence. The phases of strong activity lasted 3-4 kyrs (millennial scale) and included 3-4 ‘rupture events’ that repeated every 0.5-1 kyr (centennial scale). Each of these ‘rupture events’ was likely a sequence of a few large earthquakes cascading in a very short time, a few months at most (monthly scale), to eventually break the entire VMF. Each earthquake apparently broke a section of the fault of 10-20 km and produced maximum surface displacements of 2-3.5 meters. The fault seems to enter a phase of intense activity when the accumulated strain reaches a specific threshold. Based on this observation, the Velino-Magnola fault seems presently in a stage of relative quiescence. Yet, it may soon re-enter a phase of paroxysmal seismic activity. If its forthcoming earthquakes are similar to those we have documented, several may occur in cascade over a short time, each with a magnitude up to 6.5-6.9. Seismic hazard is thus high in the Lazio-Abruzzo region, especially in the Fucino area. References: Schlagenhauf A., Y. Gaudemer, L. Benedetti, I. Manighetti, L. Palumbo, I. Schimmelpfennig, R. Finkel, and K. Pou (2010). Using in-situ Chlorine-36 cosmonuclide to recover past earthquake histories on limestone normal fault scarps: A</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016EGUGA..1815392T&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016EGUGA..1815392T&link_type=ABSTRACT"><span id="translatedtitle">Slip rate variability over the Holocene period in the middle Aterno fault system (Italy), retrieved from in situ <span class="hlt">36</span><span class="hlt">Cl</span> cosmogenic nuclide dating of exhumed fault-plane.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tesson, Jim; Benedetti, Lucilla; Pucci, Stefano; Villani, Fabio; Bourles, Didier; Keddadouche, Karim; Aumaitre, Georges</p> <p>2016-04-01</p> <p>Numerous numerical modeling studies have described and quantified non-stochastic spatio-temporal variations of earthquake occurrences within fault-networks, such as temporal clustered earthquakes or fault synchronization. However, very few long-enough paleoseismological and geological records are available to test those models against well-constrained dataset and thus account for such variability in the fault behavior. The prerequisites for improving our understanding of fault-rupture processes and thus our capacity to better assess seismic hazard are to acquire paleoseismological records that enable to derive both long-term slip-rate and short-term variability, on a large population of faults and/or within a fault system. These conditions met in Central Apennines, an extensional province where substantial paleoseismological dataset accurately described the Holocene seismic history of a dense network of normal faults. In this study we use <span class="hlt">36</span><span class="hlt">Cl</span> in situ cosmogenic nuclide to retrieve the seismic history of 3 faults belonging to the Middle Aterno fault system, from north to south: the Bazzano fault, the Roccapreturo fault and the Sulmona fault, a portion of which ruptured during the 2009 L'Aquila earthquake in Italy. We use a new modeling approach to determine the age and slip of past seismic events from the <span class="hlt">36</span><span class="hlt">Cl</span> concentration profiles. This model is based on an inverse approach and uses an optimization algorithm enabling all the parameter space (number of events, age and slip of events, pre-exposure) to be explored without a priori constraints (see Tesson et al. in session TS4.2/NH4.16/SM3.8). Using this new approach, we precisely determine the slip events occurrences over the Holocene period of those three faults. The results indicate that the three studied faults have ruptured between 4.5 and 5.5 ka, while the southernmost part of the system has also ruptured between at 1.5-3 ka (Sulmona fault and southern segment of Roccapreturo). Those results are in agreement</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21199603','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21199603"><span id="translatedtitle">Lowest l=0 proton resonance in {sup 26}Si and implications for nucleosynthesis of {sup <span class="hlt">26</span>}<span class="hlt">Al</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Peplowski, P. N.; Baby, L. T.; Wiedenhoever, I.; Diffenderfer, E.; Hoeflich, P.; Rojas, A.; Volya, A.; Dekat, S. E.; Gay, D. L.; Grubor-Urosevic, O.; Kaye, R. A.; Keeley, N.</p> <p>2009-03-15</p> <p>Using a beam of the radioactive isotope {sup 25}Al, produced with the new RESOLUT facility, we measured the direct (d,n) proton-transfer reaction leading to low-lying proton resonances in {sup 26}Si. We observed the lowest l=0 proton resonance, identified with the 3{sup +} state at 5.914-MeV excitation energy. This result eliminates the largest uncertainty in astrophysical reaction rates involved in the nucleosynthesis of {sup <span class="hlt">26</span>}<span class="hlt">Al</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26274415','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26274415"><span id="translatedtitle">Measurement of 23Na(α,p)26Mg at Energies Relevant to <span class="hlt">26</span><span class="hlt">Al</span> Production in Massive Stars.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tomlinson, J R; Fallis, J; Laird, A M; Fox, S P; Akers, C; Alcorta, M; Bentley, M A; Christian, G; Davids, B; Davinson, T; Fulton, B R; Galinski, N; Rojas, A; Ruiz, C; de Séréville, N; Shen, M; Shotter, A C</p> <p>2015-07-31</p> <p><span class="hlt">26</span><span class="hlt">Al</span> is an important radioisotope in astrophysics that provides evidence of ongoing nucleosynthesis in the Galaxy. The 23Na(α, p)26Mg reaction has been identified by a sensitivity study as being one of the most important reactions for the production of <span class="hlt">26</span><span class="hlt">Al</span> in the convective C/Ne burning shell of massive stars. Owing to large uncertainties in previous experimental data, model calculations are used for the reaction rate of 23Na(α, p)26Mg in this sensitivity study. Current experimental data suggest a reaction rate a factor of ∼40 higher than model calculations. However, a new measurement of this reaction cross section has been made in inverse kinematics in the energy range E(c.m.)=1.28-3.15  MeV at TRIUMF, and found to be in reasonable agreement with the model calculation. A new reaction rate is calculated and tight constraints on the uncertainty in the production of <span class="hlt">26</span><span class="hlt">Al</span>, due to this reaction, are determined. PMID:26274415</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26274415','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26274415"><span id="translatedtitle">Measurement of 23Na(α,p)26Mg at Energies Relevant to <span class="hlt">26</span><span class="hlt">Al</span> Production in Massive Stars.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tomlinson, J R; Fallis, J; Laird, A M; Fox, S P; Akers, C; Alcorta, M; Bentley, M A; Christian, G; Davids, B; Davinson, T; Fulton, B R; Galinski, N; Rojas, A; Ruiz, C; de Séréville, N; Shen, M; Shotter, A C</p> <p>2015-07-31</p> <p><span class="hlt">26</span><span class="hlt">Al</span> is an important radioisotope in astrophysics that provides evidence of ongoing nucleosynthesis in the Galaxy. The 23Na(α, p)26Mg reaction has been identified by a sensitivity study as being one of the most important reactions for the production of <span class="hlt">26</span><span class="hlt">Al</span> in the convective C/Ne burning shell of massive stars. Owing to large uncertainties in previous experimental data, model calculations are used for the reaction rate of 23Na(α, p)26Mg in this sensitivity study. Current experimental data suggest a reaction rate a factor of ∼40 higher than model calculations. However, a new measurement of this reaction cross section has been made in inverse kinematics in the energy range E(c.m.)=1.28-3.15  MeV at TRIUMF, and found to be in reasonable agreement with the model calculation. A new reaction rate is calculated and tight constraints on the uncertainty in the production of <span class="hlt">26</span><span class="hlt">Al</span>, due to this reaction, are determined.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21448880','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21448880"><span id="translatedtitle">{sup 60}Fe AND {sup <span class="hlt">26</span>}<span class="hlt">Al</span> IN CHONDRULES FROM UNEQUILIBRATED CHONDRITES: IMPLICATIONS FOR EARLY SOLAR SYSTEM PROCESSES</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Mishra, R. K.; Goswami, J. N.; Rudraswami, N. G.; Tachibana, S.; Huss, G. R.</p> <p>2010-05-10</p> <p>The presence of about a dozen short-lived nuclides in the early solar system, including {sup 60}Fe and {sup <span class="hlt">26</span>}<span class="hlt">Al</span>, has been established from isotopic studies of meteorite samples. An accurate estimation of solar system initial abundance of {sup 60}Fe, a distinct product of stellar nucleosynthesis, is important to infer the stellar source of this nuclide. Previous studies in this regard suffered from the lack of exact knowledge of the time of formation of the analyzed meteorite samples. We present here results obtained from the first combined study of {sup 60}Fe and {sup <span class="hlt">26</span>}<span class="hlt">Al</span> records in early solar system objects to remove this ambiguity. Chondrules from unequilibrated ordinary chondrites belonging to low petrologic grades were analyzed for their Fe-Ni and Al-Mg isotope systematics. The Al-Mg isotope data provide the time of formation of the analyzed chondrules relative to the first solar system solids, the Ca-Al-rich inclusions. The inferred initial {sup 60}Fe/{sup 56}Fe values of four chondrules, combined with their time of formation based on Al-Mg isotope data, yielded a weighted mean value of (6.3 {+-} 2) x 10{sup -7} for solar system initial {sup 60}Fe/{sup 56}Fe. This argues for a high-mass supernova as the source of {sup 60}Fe along with {sup <span class="hlt">26</span>}<span class="hlt">Al</span> and several other short-lived nuclides present in the early solar system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JGRD..121.8125P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JGRD..121.8125P"><span id="translatedtitle">Production of cosmogenic isotopes 7Be, 10Be, 14C, 22Na, and <span class="hlt">36</span><span class="hlt">Cl</span> in the atmosphere: Altitudinal profiles of yield functions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Poluianov, S. V.; Kovaltsov, G. A.; Mishev, A. L.; Usoskin, I. G.</p> <p>2016-07-01</p> <p>New consistent and precise computations of the production of five cosmogenic radioisotopes, 7Be, 10Be, 14C, 22Na, and <span class="hlt">36</span><span class="hlt">Cl</span>, in the Earth's atmosphere by cosmic rays are presented in the form of tabulated yield functions. For the first time, a detailed set of the altitude profiles of the production functions is provided which makes it possible to apply the results directly as input for atmospheric transport models. Good agreement with most of the earlier published works for columnar and global isotopic production rates is shown. Altitude profiles of the production are important, in particular for such tasks as studies of strong solar particle events in the past, precise reconstructions of solar activity on long-term scale, tracing air mass dynamics using cosmogenic radioisotopes, etc. As an example, computations of the 10Be deposition flux in the polar region are shown for the last decades and also for a period around 780 A.D. and confronted with the actual measurements in Greenland and Antarctic ice cores.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1018000','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1018000"><span id="translatedtitle">Formation of short-lived radionuclides in the protoplanetary disk during late-stage irradiation of a volatile-rich reservoir</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Jacobsen, B; Matzel, J; Hutcheon, I D; Krot, A N; Yin, Q -; Nagashima, K; Ramon, E; Weber, P; Ishii, H; Ciesla, F</p> <p>2010-11-30</p> <p>The origin of short-lived (t{sub 1/2} < 5 Myr) and now extinct radionuclides ({sup 10}Be, {sup <span class="hlt">26</span>}<span class="hlt">Al</span>, {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>, {sup <span class="hlt">41</span>}<span class="hlt">Ca</span>, {sup 53}Mn, {sup 60}Fe; hereafter SLRs) is fundamental to understanding the formation of the early solar system. Two distinct classes of models have been proposed to explain the origin of SLRs: (1) injection from a nearby stellar source (e.g., supernova, asymptotic giant branch star or Wolf-Rayet star) and (2) solar energetic particle irradiation of dust and gas near the proto-Sun. Recent studies have demonstrated that {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> was extant in the early solar system. However, its presence, initial abundance and the noticeable decoupling from {sup <span class="hlt">26</span>}<span class="hlt">Al</span> raise serious questions about the origin of SLRs. Here we report {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>-{sup 36}S and {sup <span class="hlt">26</span>}<span class="hlt">Al</span>-{sup 26}Mg systematics for wadalite and grossular, secondary minerals in a calcium-aluminum-rich inclusion (CAI) from the CV chondrite Allende that allow us to reassess the origin of SLRs. The inferred abundance of {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> in wadalite, corresponding to a {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>/{sup 35}Cl ratio of (1.81 {+-} 0.13) x 10{sup -5}, is the highest {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> abundance reported in any early solar system material. The high level of {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> in wadalite and the absence of {sup <span class="hlt">26</span>}<span class="hlt">Al</span> ({sup <span class="hlt">26</span>}<span class="hlt">Al</span>/{sup 27}Al {le} 3.9 x 10{sup -6}) in co-existing grossular indicates that (1) {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> formed by late-stage solar energetic particle irradiation and (2) the production of {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>, recorded by secondary minerals, is unrelated to the origin of {sup <span class="hlt">26</span>}<span class="hlt">Al</span> and other SLRs ({sup 10}Be, {sup 53}Mn) recorded by primary minerals of CAIs and chondrules. We conclude that <span class="hlt">36</span><span class="hlt">Cl</span> was produced by solar energetic particle irradiation of a volatile-rich reservoir in an optically thin protoplanetary disk adjacent to the accretion region of the CV chondrite parent asteroid.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.6633R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.6633R"><span id="translatedtitle">Multiple dating approach (14C, U/Th and <span class="hlt">36</span><span class="hlt">Cl</span>) of tsunami-transported reef-top megaclasts on Bonaire (Leeward Antilles) - potential and current limitations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rixhon, Gilles; May, Simon Matthias; Engel, Max; Mechernich, Silke; Keulertz, Rebecca; Schroeder-Ritzrau, Andrea; Fohlmeister, Jens; Frank, Norbert; Dunai, Tibor; Brueckner, Helmut</p> <p>2016-04-01</p> <p>Coastal hazard assessment depends on reliable information on the magnitude and frequency of past high-energy wave events (EWE: tsunamis, storms). For this purpose onshore sedimentary records represent promising geo-archives for the mid- and late-Holocene EWE history. In comparison to fine-grained sediments which have been extensively studied in the recent past, supralittoral megaclasts are less investigated, essentially due to the difficulties related to the dating of corresponding depositional events, and thus their limited value for inferring the timing of major events. On Bonaire (Leeward Antilles, Caribbean), supratidal coarse-clast deposits form prominent landforms all around the island. Fields of large boulders (up to 150 t) are among the best-studied reef-top megaclasts worldwide. Transport by Holocene tsunamis is assumed at least for the largest boulders (Engel and May, 2012). Although a large dataset of 14C and electron spin resonance (ESR) ages is available for major coral rubble ridges and ramparts, showing some age clusters during the Late Holocene, it is still debated whether these data reflect the timing of major depositional/transport event(s), and how these data sets are biased by reworking of coral fragments. In addition, different processes may be responsible for the deposition of the coral rubble ridges and ramparts (storm) and the solitary megaclasts (tsunami). As an attempt to overcome the current challenges for dating the dislocation of the megaclasts, three distinct dating methods were implemented: (i) 14C dating of boring bivalves (Lithophaga) attached to the boulders; (ii) uranium-series (U/Th) dating of post-depositional, secondary calcitic flowstone at the underside of the boulders; and (iii) surface exposure dating of overturned boulders via <span class="hlt">36</span><span class="hlt">Cl</span> concentration measurements in corals. The three 14C datings yield age estimates >37 ka, i.e. most probably beyond the applicability of the method, which sheds doubt on the usefulness of this</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016QSRv..150..130S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016QSRv..150..130S"><span id="translatedtitle">Implications of <span class="hlt">36</span><span class="hlt">Cl</span> exposure ages from Skye, northwest Scotland for the timing of ice stream deglaciation and deglacial ice dynamics</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Small, David; Rinterknecht, Vincent; Austin, William E. N.; Bates, Richard; Benn, Douglas I.; Scourse, James D.; Bourlès, Didier L.; Hibbert, Fiona D.</p> <p>2016-10-01</p> <p>Geochronological constraints on the deglaciation of former marine based ice streams provide information on the rates and modes by which marine based ice sheets have responded to external forcing factors such as climate change. This paper presents new <span class="hlt">36</span><span class="hlt">Cl</span> cosmic ray exposure dating from boulders located on two moraines (Glen Brittle and Loch Scavaig) in southern Skye, northwest Scotland. Ages from the Glen Brittle moraines constrain deglaciation of a major marine terminating ice stream, the Barra-Donegal Ice Stream that drained the former British-Irish Ice Sheet, depending on choice of production method and scaling model this occurred 19.9 ± 1.5-17.6 ± 1.3 ka ago. We compare this timing of deglaciation to existing geochronological data and changes in a variety of potential forcing factors constrained through proxy records and numerical models to determine what deglaciation age is most consistent with existing evidence. Another small section of moraine, the Scavaig moraine, is traced offshore through multibeam swath-bathymetry and interpreted as delimiting a later stillstand/readvance stage following ice stream deglaciation. Additional cosmic ray exposure dating from the onshore portion of this moraine indicate that it was deposited 16.3 ± 1.3-15.2 ± 0.9 ka ago. When calculated using the most up-to-date scaling scheme this time of deposition is, within uncertainty, the same as the timing of a widely identified readvance, the Wester Ross Readvance, observed elsewhere in northwest Scotland. This extends the area over which this readvance has potentially occurred, reinforcing the view that it was climatically forced.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003AGUFM.T51C..06D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003AGUFM.T51C..06D"><span id="translatedtitle">First Constraints On the Slip Rate of the Yammouneh Fault (Levant Fault System) Determined by Cosmogenic \\textsuperscript{<span class="hlt">36</span>}<span class="hlt">Cl</span> Exposure Dating of Offset Alluvial Fans</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Daëron, M.; Benedetti, L.; Tapponnier, P.; Sursock, A.; Finkel, R.</p> <p>2003-12-01</p> <p>The most active seismogenic structure along the eastern shore of the Mediterranean is the left-lateral strike-slip Levant fault, plate boundary between Arabia and Africa. To this day there is consensus neither on its present slip rate and segmentation, nor on the exact size and frequence of the earthquakes it generates. Between latitudes 33\\textsuperscript{o} N and 35\\textsuperscript{o} N in Lebanon, the Levant fault's trace veers eastwards by 24\\textsuperscript{o}, forming a 160km-long restraining bend, responsible for the uplift of Mount Lebanon (3083m). Most of the resulting transpressive deformation is partitioned between two main structures: the offshore Tripoli-Beirut thrust and the Yammouneh strike-slip fault, whose degree of seismogenic activity has been questioned (various estimations of its modern slip rate range from 0 to 8mm/yr). Using aerial photographs, satellite images, topographic maps and field observations, we mapped and measured left-laterally offset alluvial fans and gullies along the Yammouneh fault. The measured offsets range from less than 10m to about 3km. To constrain the slip rate of the Yammouneh fault, limestone cobbles were sampled on three alluvial fans, each offset by 40--50m. The concentrations of \\textsuperscript{<span class="hlt">36</span>}<span class="hlt">Cl</span>\\ and stable Chlorine in the 48 samples were measured by accelerator mass spectrometry at the LLNL-CAMS. The first results suggest an average slip rate of 5--10mm/yr along the Yammouneh fault in the last 8,000 years.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014Geomo.219..201F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014Geomo.219..201F"><span id="translatedtitle"><span class="hlt">26</span><span class="hlt">Al</span>/10Be dating of an aeolian dust mantle soil in western New South Wales, Australia</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fisher, Adrian; Fink, David; Chappell, John; Melville, Michael</p> <p>2014-08-01</p> <p>Aeolian dust mantle soils are an important element of many landscapes in south-eastern Australia, though the age of these aeolian deposits has not been radiometrically determined. At Fowlers Gap in western New South Wales, surface cobbles of silcrete and quartz overlie a stone-free, aeolian dust mantle soil, which has a thickness of about 1.6 m. The clay-rich aeolian dust deposit in turn lies upon a buried silcrete and quartz stone layer. Modelling in-situ cosmogenic <span class="hlt">26</span><span class="hlt">Al</span> and 10Be concentrations measured in both the surface quartz stones and in the buried quartz layer of rocks, reveals that each has experienced a complex exposure-burial history. Due to the absence of quartz stones or sand at intermediate depths, our cosmogenic <span class="hlt">26</span><span class="hlt">Al</span> and 10Be modelling was not able to determine a definitive mechanism of stone pavement formation and stone burial. Various scenarios of stone formation, transport, burial and exhumation were tested that constrain the age of the deposit to range from 0.9 ± 0.2 Ma to 1.8 ± 0.2 Ma, based largely on different assumptions taken for the time-dependency of the net sedimentation rate. This corresponds with the initiation of the Simpson Desert dune fields and the deflation of lakes in central Australia, which probably responded to the shift to longer-wavelength, larger-amplitude Quaternary glacial cycles at around 1 Ma. Sensitivity analyses were carried out to identify those parameters which better constrained model outputs. Within model errors, which largely are the result of analytical errors in measured <span class="hlt">26</span><span class="hlt">Al</span> and 10Be concentrations, all three competing theories of colluvial wash, upward displacement of stones, and cumulic pedogenesis are possible mechanisms for the formation of the surface stone pavement.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21596675','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21596675"><span id="translatedtitle">Precise measurement of the half-life of the Fermi {beta} decay of {sup <span class="hlt">26</span>}<span class="hlt">Al</span>{sup m}</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Scott, Rebecca J.; Thompson, Maxwell N.; Rassool, Roger P.; O'Keefe, Graeme J.</p> <p>2011-08-15</p> <p>State-of-the-art signal digitization and analysis techniques have been used to measure the half-life of the Fermi {beta} decay of {sup <span class="hlt">26</span>}<span class="hlt">Al</span>{sup m}. The half-life was determined to be 6347.8 {+-} 2.5 ms. This new datum contributes to the experimental testing of the conserved-vector-current hypothesis and the required unitarity of the Cabibbo-Kobayashi-Maskawa matrix: two essential components of the standard model. Detailed discussion of the experimental techniques and data analysis and a thorough investigation of the statistical and systematic uncertainties are presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70029271','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70029271"><span id="translatedtitle">Dating offset fans along the Mojave section of the San Andreas fault using cosmogenic <span class="hlt">26</span><span class="hlt">Al</span> and 10Be</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Matmon, A.; Schwartz, D.P.; Finkel, R.; Clemmens, S.; Hanks, T.</p> <p>2005-01-01</p> <p>Analysis of cosmogenic 10Be and <span class="hlt">26</span><span class="hlt">Al</span> in samples collected from exposed boulders (n = 20) and from buried sediment (n = 3) from offset fans along the San Andreas fault near Little Rock, California, yielded ages, ranging from 16 to 413 ka, which increase with distance from their source at the mouth of Little Rock Creek. In order to determine the age of the relatively younger fans, the erosion rate of the boulders and the cosmogenic nuclide inheritance from exposure prior to deposition in the fan were established. Cosmogenic nuclide inheritance values that range between 8.5 ?? 103 and 196 ?? 103 atoms 10Be g-1 quartz were determined by measuring the concentrations and ratios of 10Be and <span class="hlt">26</span><span class="hlt">Al</span> in boulders (n = 10) and fine sediment (n = 7) at the outlet of the present active stream. Boulder erosion rate, ranging between 17 and 160 mm k.y.-1, was estimated by measuring 10Be and <span class="hlt">26</span><span class="hlt">Al</span> concentrations in nearby bedrock outcrops (n = 8). Since the boulders on the fans represent the most resistant rocks in this environment, we used the lowest rate for the age calculations. Monte Carlo simulations were used to determine ages of 16 ?? 5 and 29 ?? 7 ka for the two younger fan surfaces. Older fans (older than 100 ka) were dated by analyzing 10Be and <span class="hlt">26</span><span class="hlt">Al</span> concentrations in buried sand samples. The ages of the three oldest fans range between 227 ?? 242 and 413 ?? 185 ka. Although fan age determinations are accompanied by large uncertainties, the results of this study show a clear trend of increasing fan ages with increasing distance from the source near Little Rock Creek and provide a long-term slip rate along this section of the San Andreas fault. Slip rate along the Mojave section of the San Andreas fault for the past 413 k.y. can be determined in several ways. The average slip rate calculated from the individual fan ages is 4.2 ?? 0.9 cm yr-1. A linear regression through the data points implies a slip rate of 3.7 ?? 1.0 cm yr-1. A most probable slip rate of 3.0 ?? 1.0 cm yr-1 is</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1992Metic..27Q.241K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1992Metic..27Q.241K"><span id="translatedtitle">The Prediction of the Saturated Activity of <span class="hlt">26</span><span class="hlt">Al</span> in Non-Antarctic Stony Meteorites from their Chemical Compositions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Keith, J. E.; Heydegger, H. R.</p> <p>1992-07-01</p> <p>We have assembled from the literature a database of over 300 non-Antarctic stony meteorites, containing information about their chemical composition, date of fall, total mass, and gas exposure age, etc. We have developed an iterative algorithm using weighted linear multivariate regression, which surveys all the independent variables in the database, recommends the best 26 models (combinations of variables) for the prediction of Al activity, and using those models, performs weighted linear multivariate regressions. By requiring that the residuals be normally distributed, under- and super-saturated meteorites are discovered and eliminated. This process is iterated until a stable solution is obtained. As a result, we obtained a set of 128 saturated, 50 unsaturated, and 10 supersaturated meteorites. We find that the expression: ^<span class="hlt">26</span><span class="hlt">Al</span> = (5.28+-0.81) . Al + (2.59+- 0.06) . Si + (1.57+-0.39) . S + (1.52+-0.59) . Ca, Chi^2(sub)nu = 2.59, where the elemental concentration is given in weight 26%, is the best predictor of the saturated ^<span class="hlt">26</span><span class="hlt">Al</span> content of a stony meteorite. We find no evidence of bias or crippling multicollinearity in this expression. About one half of the remaining variability cannot be attributed to uncertainties in the determination of the ^<span class="hlt">26</span><span class="hlt">Al</span> content and thus must be attributed to variations in orbit, shielding, etc. We compare our results (see figure) with those of other workers (1,2,3,4), and examine the probable causes of the disagreements displayed there. We show that saturated ^<span class="hlt">26</span><span class="hlt">Al</span> is distributed among all classes of meteorites in about the same way, with the exception of the carbonaceous chondrites and the eucrites, which both have about the same excess proportion of unsaturation. We examine the question of the convergence of expressions derived from regressions on chemical composition to the predictive expressions derived from integrals of particle fluxes and nuclear reaction cross sections and show that they need not converge. We examine the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014QSRv...90..106Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014QSRv...90..106Z"><span id="translatedtitle">Mid-Holocene cluster of large-scale landslides revealed in the Southwestern Alps by <span class="hlt">36</span><span class="hlt">Cl</span> dating. Insight on an Alpine-scale landslide activity</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zerathe, Swann; Lebourg, Thomas; Braucher, Régis; Bourlès, Didier</p> <p>2014-04-01</p> <p>Although it is generally assumed that the internal structure of a slope (e.g. lithology and rock mass properties, inherited faults and heterogeneities, etc.) is preponderant for the progressive development of large-scale landslides, the ability to identify triggering factors responsible for final slope failures such as glacial debuttressing, seismic activities or climatic changes, especially when considering landslide cluster at an orogen-scale, is still debated. Highlighting in this study the spatial and temporal concordant clustering of deep-seated slope failures in the external Southwestern Alps, we discuss and review the possible causes for such wide-spread slope instabilities at both local and larger (Alpine) scale. High resolution field mapping coupled with electrical resistivity tomography first allows establishing an inventory of large landslides in the Southwestern Alps, determining their structural model, precising their depth limit (100-200 m) as well as the involved rock volumes (>107 m3). We show that they developed in the same geostructural context of thick mudstone layers overlain by faulted limestone and followed a block-spread model of deformation that could evolve in rock-collapse events. Cosmic ray exposure dating (CRE), using both <span class="hlt">36</span><span class="hlt">Cl</span> and 10Be in coexisting limestone and chert, respectively, has been carried out from the main scarps of six Deep Seated Landslides (DSL) and leads to landslide-failure CRE ages ranging from 3.7 to 4.7 ka. They highlighted: (i) mainly single and fast ruptures and (ii) a possible concomitant initiation with a main peak of activity between 3.3 and 5.1 ka, centered at ca 4.2 ka. Because this region was not affected by historical glaciations events, landslide triggering by glacial unloading can be excluded. The presented data combined with field observations preferentially suggest that these failures were climatically driven and were most likely controlled by high pressure changes in the karstic medium. In effect, the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015GeCoA.169...99K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015GeCoA.169...99K"><span id="translatedtitle"><span class="hlt">26</span><span class="hlt">Al</span>-26Mg chronology and oxygen isotope distributions of multiple melting for a Type C CAI from Allende</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kawasaki, Noriyuki; Kato, Chizu; Itoh, Shoichi; Wakaki, Shigeyuki; Ito, Motoo; Yurimoto, Hisayoshi</p> <p>2015-11-01</p> <p>Disequilibrium oxygen isotopic distributions of Ca-Al-rich inclusions (CAIs) correspond to multiple melting events in the solar nebula. <span class="hlt">26</span><span class="hlt">Al</span>-26Mg systematics may be applicable for age differences among such melting events. We have carried out a coordinated study of detailed petrographic observations and in-situ oxygen and magnesium isotope measurements for a Type C CAI, EK1-04-2, from the Allende CV3 meteorite to determine the melting events and their ages. The CAI consists mainly of spinel, anorthite, olivine, and pyroxene, and has a core and mantle structure. Petrography of the core suggests that the crystallization sequence of the core minerals is from spinel, anorthite, olivine, and to pyroxene. The mantle has the same mineral assemblage as the core, and shows incomplete melting and solidification textures. Oxygen isotopic compositions of the minerals are distributed along the carbonaceous chondrite anhydrous mineral (CCAM) line (δ18O = -44‰ to +9‰), which indicates to preserve a chemical disequilibrium status in the CAI. Spinel shows a 16O-rich signature (δ18O ∼ -43‰), while anorthite is 16O-poor (δ18O ∼ +8‰). Olivine and pyroxene in the core have the same oxygen isotopic composition (δ18O ∼ -15‰), which indicates their equilibrium. Olivine and pyroxene in the mantle have variable oxygen isotopic compositions and are slightly depleted in 16O (δ18O = -13‰ to -4‰) compared with the same minerals in the core. The <span class="hlt">26</span><span class="hlt">Al</span>-26Mg systematics is consistent with the disequilibrium status observed according to the petrography and oxygen isotopes. Spinel is plotted on a line of (<span class="hlt">26</span><span class="hlt">Al</span>/27Al)0 = (3.5 ± 0.2) × 10-5, anorthite is plotted on a line of (-1 ± 5) × 10-7, and olivine and pyroxene in the core are plotted on a line of (-1 ± 7) × 10-6. Plots of olivine and pyroxene in the mantle are scattered below the isochron of these minerals in the core. This study indicates that the EK1-04-2 Type C CAI underwent multiple heating events after the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22167129','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22167129"><span id="translatedtitle">IMPACT OF A REVISED {sup 25}Mg(p, {gamma}){sup <span class="hlt">26</span>}<span class="hlt">Al</span> REACTION RATE ON THE OPERATION OF THE Mg-Al CYCLE</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Straniero, O.; Cristallo, S.; Imbriani, G.; DiLeva, A.; Limata, B.; Strieder, F.; Bemmerer, D.; Broggini, C.; Caciolli, A.; Corvisiero, P.; Costantini, H.; Lemut, A.; Formicola, A.; Gustavino, C.; Junker, M.; Elekes, Z.; Fueloep, Zs.; Gyuerky, Gy.; Gervino, G.; Guglielmetti, A.; and others</p> <p>2013-02-15</p> <p>Proton captures on Mg isotopes play an important role in the Mg-Al cycle active in stellar H-burning regions. In particular, low-energy nuclear resonances in the {sup 25}Mg(p, {gamma}){sup <span class="hlt">26</span>}<span class="hlt">Al</span> reaction affect the production of radioactive {sup <span class="hlt">26</span>}<span class="hlt">Al</span>{sup gs} as well as the resulting Mg/Al abundance ratio. Reliable estimations of these quantities require precise measurements of the strengths of low-energy resonances. Based on a new experimental study performed at the Laboratory for Underground Nuclear Astrophysics, we provide revised rates of the {sup 25}Mg(p, {gamma}){sup <span class="hlt">26</span>}<span class="hlt">Al</span>{sup gs} and the {sup 25}Mg(p, {gamma}){sup <span class="hlt">26</span>}<span class="hlt">Al</span> {sup m} reactions with corresponding uncertainties. In the temperature range 50-150 MK, the new recommended rate of {sup <span class="hlt">26</span>}<span class="hlt">Al</span> {sup m} production is up to five times higher than previously assumed. In addition, at T = 100 MK, the revised total reaction rate is a factor of two higher. Note that this is the range of temperature at which the Mg-Al cycle operates in a H-burning zone. The effects of this revision are discussed. Due to the significantly larger {sup 25}Mg(p, {gamma}){sup <span class="hlt">26</span>}<span class="hlt">Al</span> {sup m} rate, the estimated production of {sup <span class="hlt">26</span>}<span class="hlt">Al</span>{sup gs} in H-burning regions is less efficient than previously obtained. As a result, the new rates should imply a smaller contribution from Wolf-Rayet stars to the galactic {sup <span class="hlt">26</span>}<span class="hlt">Al</span> budget. Similarly, we show that the asymptotic giant branch (AGB) extra-mixing scenario does not appear able to explain the most extreme values of {sup <span class="hlt">26</span>}<span class="hlt">Al</span>/{sup 27}Al, i.e., >10{sup -2}, found in some O-rich presolar grains. Finally, the substantial increase of the total reaction rate makes the hypothesis of self-pollution by massive AGBs a more robust explanation for the Mg-Al anticorrelation observed in globular-cluster stars.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007NIMPB.259..600F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007NIMPB.259..600F"><span id="translatedtitle">An inter-comparison of 10Be and <span class="hlt">26</span><span class="hlt">Al</span> AMS reference standards and the 10Be half-life</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fink, David; Smith, Andrew</p> <p>2007-06-01</p> <p>We have completed a survey and inter-comparison of several 10Be and <span class="hlt">26</span><span class="hlt">Al</span> standard reference materials (SRMs) that are in routine use at various AMS laboratories to assess their relative values and the accuracy of their quoted nominal ratios. The accelerator measurement cycle, analysis procedure and setup used at the ANTARES AMS facility for this survey are described. We focused on a new set of 10Be and <span class="hlt">26</span><span class="hlt">Al</span> serial dilutions of standard reference materials (SRMs) prepared by Kuni Nishiizumii at the University of California, Berkeley, and found excellent systematic reproducibility and internal consistency. For other standard materials, minor deviations are evident even when the results have been recalibrated to a common half-life. In particular, we confirm that the NIST 10Be SRM-4325 has a 14% greater 10Be/Be ratio than that certified by NIST when it is calibrated against other SRMs whose ratios have been normalized to a common 1.5 Ma 10Be half-life. In order to investigate this apparent discrepancy, we report on the results of an absolute, normalization independent, measure of the NIST-4325 10Be/Be ratio. Within the constraints of this type of measurement and its systematic errors, we determine an absolute value for the 10Be/Be SRM-4325 ratio in the range 26,050 to 24,800 × 10-15 in support of the certified value of 26,800 × 10-15 given by NIST. We hesitate to directly infer as a consequence that the 10Be half-life is 1.34 Ma because such an inference is contingent on a direct and accurate specific activity in the parent solution, which at present is not available.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_9 --> <div id="page_10" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="181"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/460041','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/460041"><span id="translatedtitle">Quaternary downcutting rate of the new river, Virginia, measured from differential decay of cosmogenic {sup <span class="hlt">26</span>}<span class="hlt">Al</span> and {sup 10}Be in cave-deposited alluvium</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Granger, D.E.; Kirchner, J.W.; Finkel, R.C.</p> <p>1997-02-01</p> <p>The concentrations of the cosmogenic radionuclides {sup <span class="hlt">26</span>}<span class="hlt">Al</span> and {sup 10}Be in quartz can be used to date sediment burial. Here we use {sup <span class="hlt">26</span>} <span class="hlt">Al</span> and {sup 10}Be in cave-deposited river sediment to infer the time of sediment emplacement. Sediment burial dates from a vertical sequence of caves along the New River constrain its Quaternary downcutting rate to 27.3{+-}4.5 m/m.y. and may provide evidence of regional tectonic tilt. 32 refs., 3 figs., 1 tab.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2000NIMPB.172..112S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000NIMPB.172..112S"><span id="translatedtitle">PRIME lab AMS performance, upgrades and research applications</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sharma, P.; Bourgeois, M.; Elmore, D.; Granger, D.; Lipschutz, M. E.; Ma, X.; Miller, T.; Mueller, K.; Rickey, F.; Simms, P.; Vogt, S.</p> <p>2000-10-01</p> <p>The Purdue Rare Isotope Measurement Laboratory (PRIME Lab) is a dedicated research and service facility for AMS that provides the scientific community with timely, reliable and high quality chemical processing (~600 samples/year) and AMS measurements (~3000 samples/year) of 10Be, 14C, <span class="hlt">26</span><span class="hlt">Al</span>, <span class="hlt">36</span><span class="hlt">Cl</span>, <span class="hlt">41</span><span class="hlt">Ca</span> and 129I. The AMS system is based on an upgraded FN (7 MV) tandem accelerator that has recently been modified to improve performance. The precision is 1% for 14C and it is 3-5% for the other nuclides for radioisotope/stable isotope ratios at the 10-12 levels. System background for 10Be, 14C, <span class="hlt">26</span><span class="hlt">Al</span>, <span class="hlt">36</span><span class="hlt">Cl</span> and <span class="hlt">41</span><span class="hlt">Ca</span> is 1-10×10-15 while for 129I the natural abundance limits it to 20×10-15. Research is being carried out in Earth, planetary, and biomedical sciences. Geoscience applications include determination of exposure ages of glacial moraines, volcanic eruptions, river terraces, and fault scarps. Burial histories of sand are being determined to decipher the timing of human expansion and climatic history. Environmental applications are tracing the release of radioactivity from nuclear fuel reprocessing plants, water tracing, and neutron dosimetry. The applications using meteoric nuclides are oil field brines, sediment subduction, radiocarbon dating, and groundwater <span class="hlt">36</span><span class="hlt">Cl</span> mapping. Radionuclide concentrations are also determined in meteorites and tektites for deciphering space and terrestrial exposure histories.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013GeCoA.110..190M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013GeCoA.110..190M"><span id="translatedtitle">Heterogeneous distribution of <span class="hlt">26</span><span class="hlt">Al</span> at the birth of the Solar System: Evidence from corundum-bearing refractory inclusions in carbonaceous chondrites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Makide, Kentaro; Nagashima, Kazuhide; Krot, Alexander N.; Huss, Gary R.; Hutcheon, Ian D.; Hellebrand, Eric; Petaev, Michail I.</p> <p>2013-06-01</p> <p>We report on the mineralogy, petrology, and in situ oxygen- and magnesium-isotope measurements using secondary ion mass spectrometry of 10 corundum-bearing calcium-aluminum-rich inclusions (CAIs) from the Adelaide (ungrouped), Murray and Murchison (CM) carbonaceous chondrites. We also measured in situ oxygen-isotope compositions of several isolated corundum grains in the matrices of Murray and Murchison. Most of the corundum-bearing objects studied are uniformly 16O-rich [Δ17O values range from -17‰ to -28‰ (2σ = ±2.5‰) (Δ17Oavr = -23 ± 5‰)], suggesting that they formed in a 16O-rich gas of approximately solar composition and largely avoided subsequent thermal processing in an 16O-poor gaseous reservoir. There is a large spread of the initial <span class="hlt">26</span><span class="hlt">Al</span>/27Al ratio [(<span class="hlt">26</span><span class="hlt">Al</span>/27Al)0] in the corundum-bearing CAIs. Two Adelaide CAIs show no resolvable excess of radiogenic 26Mg (δ26Mg∗): the inferred (<span class="hlt">26</span><span class="hlt">Al</span>/27Al)0 are (0.6 ± 2.0) × 10-6 and (-0.9 ± 1.2) × 10-6, respectively. Slopes of the model <span class="hlt">26</span><span class="hlt">Al</span>-26Mg isochrons in five CAIs from Murray and Murchison are (4.4 ± 0.2) × 10-5, (3.3 ± 0.3) × 10-5, (4.1 ± 0.3) × 10-5, (3.9 ± 0.4) × 10-5, and (4.0 ± 2.0) × 10-6, respectively. These values are lower than the canonical (<span class="hlt">26</span><span class="hlt">Al</span>/27Al)0 ratio of (5.23 ± 0.13) × 10-5 inferred from the whole-rock magnesium-isotope measurements of the CV CAIs, but similar to the (<span class="hlt">26</span><span class="hlt">Al</span>/27Al)0 ratio of (4.1 ± 0.2) × 10-5 in the corundum-bearing CAI F5 from Murray. Five other previously studied corundum-bearing CAIs from Acfer 094 (ungrouped) and CM carbonaceous chondrites showed no resolvable δ26Mg∗. We conclude that the corundum-bearing CAIs, as well as the solar corundum grains from matrices and acid-resistant residues of unequilibrated ordinary and carbonaceous chondrites, recorded heterogeneous distribution of <span class="hlt">26</span><span class="hlt">Al</span> in the Solar System during an epoch of CAI formation. The <span class="hlt">26</span><span class="hlt">Al</span>-rich and <span class="hlt">26</span><span class="hlt">Al</span>-poor corundum-bearing CAIs and solar corundum grains represent different</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFMEP33D..07H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFMEP33D..07H"><span id="translatedtitle">Eroding and Inflating the Atacama Desert, Chile: Insights Through Cosmogenic 10-Be, <span class="hlt">26</span>-<span class="hlt">Al</span> and 21-Ne</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Heimsath, A. M.; Jungers, M. C.; Amundson, R.; Balco, G.; Shuster, D. L.</p> <p>2010-12-01</p> <p>Enigmas of the Atacama Desert are as abundant as the hypotheses formulated to explain them. This fascinating and extreme landscape attracts scientists from disparate disciplines, spawning remarkable insights into the connections between climate, tectonics, biota and landscape evolution. Recent work explores such connections on timescales ranging from millions to thousands of years. Both the timing of the onset of hyperaridity in the Atacama and its relationship to the uplift of the Andes are especially well-debated topics. Similarly enigmatic, but less widely studied, are the connections between the timing of hyperaridity and the surface morphology of the region. Specifically, the extent, nature, and timing of formation for the extensive salars across the Atacama are undeniably linked to the climate history of the region. Adjacent to the extensive salars are landscapes that appear to be shaped by processes more typically associated with temperate landscapes: rilling and gullying, extensive terrace deposition, steep fault scarps, landslide deposits, and extensive fan and paleosurface deposits. Our primary goal in this project is to establish chronologies and rates for the surface processes driving landscape evolution for two field regions in the Atacama. To achieve this goal we are also testing and expanding upon the burial dating methodology (Balco and Shuster, 2009) that couples the stable cosmogenic nuclide, 21Ne, with the radiogenic nuclides, 10Be and <span class="hlt">26</span><span class="hlt">Al</span>. Here we present new results from remarkably different field settings from the north-central Atacama. The southern region, inland from Antofagasta, is relatively well studied to determine how the onset of hyperaridity impacted water-driven processes. The northern region, north of the Rio Loa and Calama, differs most notably by the enormous basin fills of salt (e.g. Salar de Llamara and Salar Grande) and evidence of more extensive recently active salars. Across both regions we use in 10Be, <span class="hlt">26</span><span class="hlt">Al</span>, and 21Ne to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014HydJ...22.1359K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014HydJ...22.1359K"><span id="translatedtitle">Testing the 14C ages and conservative behavior of dissolved 14C in a carbonate aquifer in Yucca Flat, Nevada (USA), using <span class="hlt">36</span><span class="hlt">Cl</span> from groundwater and packrat middens</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kwicklis, Edward; Farnham, Irene</p> <p>2014-09-01</p> <p>Corrected groundwater 14C ages from the carbonate aquifer in Yucca Flat at the former Nevada Test Site (now the Nevada National Security Site), USA, were evaluated by comparing temporal variations of groundwater <span class="hlt">36</span><span class="hlt">Cl</span>/Cl estimated with these 14C ages with published records of meteoric <span class="hlt">36</span><span class="hlt">Cl</span>/Cl variations preserved in packrat middens (piles of plant fragments, fecal matter and urine). Good agreement between these records indicates that the groundwater 14C ages are reasonable and that 14C is moving with chloride without sorbing to the carbonate rock matrix or fracture coatings, despite opposing evidence from laboratory experiments. The groundwater 14C ages are consistent with other hydrologic evidence that indicates significant basin infiltration ceased 8,000 to 10,000 years ago, and that recharge to the carbonate aquifer is from paleowater draining through overlying tuff confining units along major faults. This interpretation is supported by the relative age differences as well as hydraulic head differences between the alluvial and volcanic aquifers and the carbonate aquifer. The carbonate aquifer 14C ages suggest that groundwater velocities throughout much of Yucca Flat are about 2 m/yr, consistent with the long-held conceptual model that blocking ridges of low-permeability rock hydrologically isolate the carbonate aquifer in Yucca Flat from the outlying regional carbonate flow system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70094758','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70094758"><span id="translatedtitle">Rates of sediment supply to arroyos from upland erosion determined using in situ produced cosmogenic 10Be and <span class="hlt">26</span><span class="hlt">Al</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Clapp, Erik M.; Bierman, Paul R.; Nichols, Kyle K.; Pavich, Milan; Caffee, Marc A.</p> <p>2001-01-01</p> <p>Using 10Be and <span class="hlt">26</span><span class="hlt">Al</span> measured in sediment and bedrock, we quantify rates of upland erosion and sediment supply to a small basin in northwestern New Mexico. This and many other similar basins in the southwestern United States have been affected by cycles of arroyo incision and backfilling several times in the past few millennia. The sediment generation (275 ± 65 g m−2 yr−1) and bedrock equivalent lowering rates (102 ± 24 m myr−1) we determine are sufficient to support at least three arroyo cycles in the past 3,000 years, consistent with rates calculated from a physical sediment budget within the basin and regional rates determined using other techniques. Nuclide concentrations measured in different sediment sources and reservoirs suggest that the arroyo is a good spatial and temporal integrator of sediment and associated nuclide concentrations from throughout the basin, that the basin is in steady-state, and that nuclide concentration is independent of sediment grain size. Differences between nuclide concentrations measured in sediment sources and reservoirs reflect sediment residence times and indicate that subcolluvial bedrock weathering on hillslopes supplies more sediment to the basin than erosion of exposed bedrock.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012JPhG...39j5201D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JPhG...39j5201D"><span id="translatedtitle">44Ti, <span class="hlt">26</span><span class="hlt">Al</span> and 53Mn samples for nuclear astrophysics: the needs, the possibilities and the sources</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dressler, R.; Ayranov, M.; Bemmerer, D.; Bunka, M.; Dai, Y.; Lederer, C.; Fallis, J.; StJ Murphy, A.; Pignatari, M.; Schumann, D.; Stora, T.; Stowasser, T.; Thielemann, F.-K.; Woods, P. J.</p> <p>2012-10-01</p> <p>Exploration of the physics involved in the production of cosmogenic radionuclides requires experiments using the same rare, radioactive nuclei in sufficient quantities. For this work, such exotic radionuclides have been extracted from previously proton-irradiated stainless steel samples using wet chemistry separation techniques. The irradiated construction material has arisen from an extended material research programme at the Paul Scherrer Institute, called STIP (SINQ Target Irradiation Program), where several thousand samples of different materials were irradiated with protons and neutrons of energies up to 570 MeV. In total, 8 × 1017 atoms of 44Ti, ˜1016 atoms of <span class="hlt">26</span><span class="hlt">Al</span> and ˜1019 atoms of 53Mn are available from selected samples. These materials may now be used to produce targets or radioactive beams for nuclear reaction studies with protons, neutrons and α-particles. The work is part of the ERAWAST initiative (Exotic Radionuclides from Accelerator Waste for Science and Technology), aimed at facilitating new collaborations between the isotope producers and users from different scientific fields including nuclear astrophysics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/449829','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/449829"><span id="translatedtitle">The Center for Accelerator Mass Spectrometry, Lawrence Livermore National Laboratory</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Roberts, M.L.; Heikkinen, D.W.; Southon, J.R.; Proctor, I.D.</p> <p>1996-10-01</p> <p>CAMS operates an HVEC FN tandem accelerator for use in both basic research and technology development. The accelerator is operated under a distributed computer control system with sophisticated auto-scaling, beam flat-topping, archiving, and recall capabilities, which makes possible rapid and precise switching between experimental configurations daily. Using the spectrometer, the AMS group can routinely measure the isotopes {sup 3}H, {sup 9}Be, {sup 10}Be, {sup 14}C, {sup <span class="hlt">26</span>}<span class="hlt">Al</span>, {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>, {sup <span class="hlt">41</span>}<span class="hlt">Ca</span>, and {sup 129}I at abundances as low as 1 part in 10{sup 16}.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012GeCoA..77..415B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012GeCoA..77..415B"><span id="translatedtitle"><span class="hlt">26</span><span class="hlt">Al</span>- 26Mg deficit dating ultramafic meteorites and silicate planetesimal differentiation in the early Solar System?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Baker, Joel A.; Schiller, Martin; Bizzarro, Martin</p> <p>2012-01-01</p> <p>Meteorites with significantly sub-chondritic Al/Mg that formed in the first 2 million years of the Solar System should be characterised by deficits in the abundance of 26Mg (δ26Mg∗) due to the absence of in-growth of 26Mg from the decay of short-lived <span class="hlt">26</span><span class="hlt">Al</span> (t1/2 = 0.73 Myr). However, these 26Mg deficits will be small (δ26Mg∗ >-0.037‰) even for material that formed at the same time as the Solar System’s oldest solids - calcium-aluminium-rich inclusions - and thus measurement of these deficits is analytically challenging. Here, we report on a search for 26Mg deficits in three types of ultramafic meteorites (pallasites, ureilites and aubrites) by multiple-collector inductively coupled plasma mass spectrometry. A range of analytical tests were carried out including analysis of: (1) a range of synthetic Mg solution standards; (2) Mg gravimetrically doped with a high purity 26Mg spike; (3) Mg cuts collected sequentially from cation exchange separation columns with fractionated stable Mg isotope compositions; (4) Mg separated from samples that was bracketed by analyses of both DSM-3 and Mg separated from a natural olivine sample subjected to the same chemical processing as the samples. These tests confirm it is possible to resolve differences in δ26Mg∗ from the terrestrial materials that are ⩽0.005‰. However, if Mg yields from chemical separation are low or an inappropriate equilibrium-isotopically fractionated standard is used this will generate analytical artefacts on δ26Mg∗ when this is calculated with the kinetic/exponential mass fractionation law as is the case when correcting for instrumental mass bias during mass spectrometric analysis. Olivine from four different main group pallasites and four bulk ureilites have small deficits in the abundance of 26Mg with δ26MgDSM-3∗=-0.0120±0.0018‰ and δ26MgDSM-3∗=-0.0062±0.0023‰, respectively, relative to terrestrial olivine (δ26MgDSM-3∗=+0.0029±0.0028‰). Six aubrites have δ26MgDSM-3</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/277041','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/277041"><span id="translatedtitle">Measurement of proton production cross sections of {sup 10}Be and {sup <span class="hlt">26</span>}<span class="hlt">Al</span> from elements found in lunar rocks</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Sisterson, J.M.; Kim, K.; Englert, P.A.J.</p> <p>1996-07-01</p> <p>Cosmic rays penetrate the lunar surface and interact with the lunar rocks to produce both radionuclides and stable nuclides. Production depth profiles for long-lived radionuclides produce in lunar rocks are measured using Accelerator Mass Spectrometry (AMS). For a particular radionuclide these production depth profiles can be interpreted to give an estimate for the solar proton flux over a time period characterized by the half life of the radionuclide under study. This analysis is possible if and only if all the cross sections for the interactions of all cosmic ray particles with all elements found in lunar rocks are well known. In practice, the most important cross sections needed are the proton production cross sections, because 98% of solar cosmic rays and {similar_to}87% of galactic cosmic rays are protons. The cross sections for the production of long-lived radionuclides were very difficult to measure before the development of AMS and only in recent years has significant progress been made in determining these essential cross sections. Oxygen and silicon are major constituents of lunar rocks. We have reported already {sup 14}C production cross sections from O and Si for proton energies 25-500 MeV, and O(p,x){sup 10}Be from 58 160 MeV[6]. Here we present new measurements for the cross sections O(p,x){sup 10}Be,O(p,x){sup 7}Be, Si(p,x){sup 7}Be,Si(p,x){sup <span class="hlt">26</span>}<span class="hlt">Al</span>, and Si(p,x){sup 22}Na from {approximately}30 - 500 MeV.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.9718N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.9718N"><span id="translatedtitle"><span class="hlt">26</span><span class="hlt">Al</span> - 10Be cosmogenic nuclide isochron burial dating in combination with luminescence dating of two Danube terraces</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Neuhuber, Stephanie; Braumann, Sandra; Lüthgens, Christopher; Fiebig, Markus; Häuselmann, Philipp; Schäfer, Jörg</p> <p>2016-04-01</p> <p>The Quaternary sediment record in the Vienna Basin is influenced by two main factors: (1) the tectonic development of a pull apart basin along a sinistral strike slip fault system between the Eastern Alps and the West Carpathians and by (2) strongly varying sediment supply during the Plio- and Pleistocene. From the Late Pannonian (8.8 Ma) onward a large-scale regional uplift (Decker et al., 2005) controls terrace formation in the Vienna Basin. The main sediment supply into the Vienna Basin originates from the Danube, and subordinately from tributaries to the south such as Piesting, Fischa, Leitha and from the north by the river March. Today the Danube forms a large floodplain that is bordered to the north by one large Pleistocene terrace, the Gänserndorf Terrace that is situated 17 m above todays water level. Farther to the east a smaller terrace, the Schlosshof Terrace, reaches 25 m above todays water level. These terrace levels are tilted by movement of underlying blocks (Peresson, 2006). Both, the Schlosshof and Gänserndorf terraces consist of successions of up to 2 m thick gravel beds with intercalated sand layers or -lenses that may locally reach thicknesses up to 0.8 m. At each terrace one gavel pit was selected to calculate the time of terrace deposition by luminescence dating in combination with <span class="hlt">26</span><span class="hlt">Al</span>/10Be cosmogenic nuclide isochrone dating (Balco and Rovery, 2008). Five quartz stones from the base of each terrace were physically and chemically processed to obtain Al and Be oxides for Acceleration Mass Spectrometry. Sand samples for luminescence dating were taken above the cosmogenic nuclide samples from the closest suitable sand body. Decker et al., 2005. QSR 24, 307-322 Peresson, 2006 Geologie der österreichischen Bundesländer Niederösterreich 255-258 Balco and Rovey, 2008. AJS 908, 1083-1114 Thanks to FWF P 23138-N19, OMAA 90öu17</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.P34C..03N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.P34C..03N"><span id="translatedtitle">Formation age and geomorphologic history of the Lonar impact crater deduced from in- situ cosmogenic 10Be and <span class="hlt">26</span><span class="hlt">Al</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nakamura, A.; Yokoyama, Y.; Sekine, Y.; Goto, K.; Komatsu, G.; Kumar, P.; Matsuzaki, H.; Matsui, T.</p> <p>2013-12-01</p> <p>Impact cratering is a dominant surface modification process on planetary surfaces. In the inner solar system, the large majority of impacts occur on bodies covered by primitive igneous rocks. However, most of the impacts remaining on Earth surface are on different rock types than that of the inner planet and hence geologic knowledge derived from Earth's surface cannot be translated readily. The Lonar crater is a 1.88-km-diameter crater located on the Deccan basaltic traps in India (ca. 65 Ma), and is one of a few craters on Earth bombarded directly on basaltic lava flows. Thus, the Lonar crater provides a rare opportunity to study impact structures on the basaltic surfaces of other terrestrial planets and the Moon. Since the ages of terrestrial impact structures is a key to understand geomorphological processes after the impact, various dating methods have been applied to the Lonar Crater such as fission track (Storzer and Koeberl, 2004), radiocarbon (Maloof, 2010), thermoluminescence (Sengupta et al., 1997), and 40Ar/39Ar (Jourdan et al., 2011). Yet, a large discrepancy between these methods ranging from ca. 1.79 to 570 ka has been resulted. Here we report surface exposure ages based on in-situ cosmogenic 10Be and <span class="hlt">26</span><span class="hlt">Al</span> in order to obtain a precise age of the Lonar crater formation as well as to study the geomorphologic evolution. The samples are collected from the topographic highs on the rim of the crater and from the ejecta blanket. Exposure ages together with newly obtained radiocarbon age of pre-impact soil indicate much younger ages than that of obtained from 40Ar/39Ar method. This suggests the potential bias because of inherited 40Ar in impact glass. Systematically young exposure age from the rim samples compared to the samples from the ejecta blanket indicate that the rim of the Lonar crater is being actively eroded. Spatial distributions of geomorphic ages observed from the Lonar creator is not the same as the pattern reported from the well</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015QSRv..126..140B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015QSRv..126..140B"><span id="translatedtitle">Cosmogenic <span class="hlt">36</span><span class="hlt">Cl</span> exposure ages reveal a 9.3 ka BP glacier advance and the Late Weichselian-Early Holocene glacial history of the Drangajökull region, northwest Iceland</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Brynjólfsson, Skafti; Schomacker, Anders; Ingólfsson, Ólafur; Keiding, Jakob K.</p> <p>2015-10-01</p> <p>We present twenty-four new cosmogenic isotope (<span class="hlt">36</span><span class="hlt">Cl</span>) surface exposure ages from erratic boulders, moraine boulders and glacially eroded bedrock that constrain the late Weichselian to Holocene glacial history of the Drangajökull region, northwest Iceland. The results suggest a topographically controlled ice sheet over the Vestfirðir (Westfjords) peninsula during the last glaciation. Cold based non-erosive sectors of the ice sheet covered most of the mountains while fjords and valleys were occupied with erosive, warm-based ice. Old<span class="hlt">36</span><span class="hlt">Cl</span> exposure ages from highlands and mountain plateaux (L8; 76.5 ka and H1; 41.6 ka) in combination with younger erratic boulders (L7; 26.2 and K1-K4; 15.0-13.8 ka) superimposed on such surfaces suggest the presence of non-erosive ice over uplands and plateaux in the Vestfirðir peninsula during the last glaciation. Glacially scoured terrain and erratic boulders yielding younger exposure ages (L1-L6; 11.3-9.1 ka and R1, R6-R7; 10.6-9.4 ka) in the lowland areas indicate that the valleys and fjords of the Vestfirðir peninsula were occupied by warm-based, dynamic ice during the last glaciation. The deglaciation of mountain Leirufjall by 26.2 ka BP suggests that ice thinning and deglaciation of some mountains and plateaux preceded any significant lateral retreat of the ice sheet. Subsequently this initial ice thinning was followed by break-up of the shelf based ice sheet off Vestfirðir about 15 ka BP. Hence, the new exposure ages suggest a stepwise asynchronous deglaciation on land, following the shelf break-up with some valleys and most of the highlands, ice free by 14-15 ka BP. The outermost moraine at the mouth of Leirufjörður is dated to 9.3 ka BP, and we suggest the moraine to be formed by a glacier re-advance in response to a cooler climate forced by the reduced Atlantic Meridional Overturning Circulation at around 9.3 ka BP. A system of moraines proximal to the 9.3 ka moraine in Leirufjörður as well as a 9.4 ka deglaciation age</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016NIMPB.370...94R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016NIMPB.370...94R"><span id="translatedtitle">The first four years of the AMS-facility DREAMS: Status and developments for more accurate radionuclide data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rugel, Georg; Pavetich, Stefan; Akhmadaliev, Shavkat; Enamorado Baez, Santiago Miguel; Scharf, Andreas; Ziegenrücker, René; Merchel, Silke</p> <p>2016-03-01</p> <p>DREAMS, the DREsden AMS-facility, is performing routine accelerator mass spectrometry of 10Be, <span class="hlt">26</span><span class="hlt">Al</span>, <span class="hlt">36</span><span class="hlt">Cl</span>, <span class="hlt">41</span><span class="hlt">Ca</span>, and 129I for a wide range of applications. All DREAMS-data is normalised directly to primary standards or traceable to those via cross-calibration of secondary standards. Recent technical developments such as a low-memory ion source for <span class="hlt">36</span><span class="hlt">Cl</span> and 129I and sophisticated tuning strategies for 129I led to improved-accuracy data. Tests of ion source output have been performed with different metal binders, sample-to-binder mixing ratios, and compaction pressures in order to find optimal parameters. The highest and most stable outputs have been obtained for 10Be, <span class="hlt">26</span><span class="hlt">Al</span>, and <span class="hlt">41</span><span class="hlt">Ca</span> for the following binders and mixing ratios (by weight): BeO:Nb, 1:4; Al2O3:Ag, 1:1; CaF2:Ag, 1:4. Higher beam currents generally result in reduced statistical uncertainty. Cross-contamination and long-term memory seem to be underestimated problems asking for further tests and improvements such as the development of low-level in-house-standards.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeCoA.184..151K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeCoA.184..151K"><span id="translatedtitle">New constraints on the relationship between <span class="hlt">26</span><span class="hlt">Al</span> and oxygen, calcium, and titanium isotopic variation in the early Solar System from a multielement isotopic study of spinel-hibonite inclusions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kööp, Levke; Nakashima, Daisuke; Heck, Philipp R.; Kita, Noriko T.; Tenner, Travis J.; Krot, Alexander N.; Nagashima, Kazuhide; Park, Changkun; Davis, Andrew M.</p> <p>2016-07-01</p> <p>We report oxygen, calcium, titanium and <span class="hlt">26</span><span class="hlt">Al</span>-26Mg isotope systematics for spinel-hibonite inclusions (SHIBs), a class of calcium-aluminum-rich inclusions (CAI) common in CM chondrites. In contrast to previous studies, our analyses of 33 SHIBs and four SHIB-related objects obtained with high spatial resolution demonstrate that these CAIs have a uniform Δ17O value of approximately -23‰, similar to many other mineralogically pristine CAIs from unmetamorphosed chondrites (e.g., CR, CV, and Acfer 094). Five SHIBs studied for calcium and titanium isotopes have no resolvable anomalies beyond 3σ uncertainties. This suggests that nucleosynthetic anomalies in the refractory elements had been significantly diluted in the environment where SHIBs with uniform Δ17O formed. We established internal <span class="hlt">26</span><span class="hlt">Al</span>-26Mg isochrons for eight SHIBs and found that seven of these formed with uniformly high levels of <span class="hlt">26</span><span class="hlt">Al</span> (a multi-CAI mineral isochron yields an initial <span class="hlt">26</span><span class="hlt">Al</span>/27Al ratio of ∼4.8 × 10-5), but one SHIB has a smaller initial <span class="hlt">26</span><span class="hlt">Al</span>/27Al of ∼ 2.5 × 10-5, indicating variation in <span class="hlt">26</span><span class="hlt">Al</span>/27Al ratios when SHIBs formed. The uniform calcium, titanium and oxygen isotopic characteristics found in SHIBs with both high and low initial <span class="hlt">26</span><span class="hlt">Al</span>/27Al ratios allow for two interpretations. (1) If subcanonical initial <span class="hlt">26</span><span class="hlt">Al</span>/27Al ratios in SHIBs are due to early formation, as suggested by Liu et al. (2012), our data would indicate that the CAI formation region had achieved a high degree of isotopic homogeneity in oxygen and refractory elements before a homogeneous distribution of <span class="hlt">26</span><span class="hlt">Al</span> was achieved. (2) Alternatively, if subcanonical ratios were the result of <span class="hlt">26</span><span class="hlt">Al</span>-26Mg system resetting, the clustering of SHIBs at a Δ17O value of ∼-23‰ would imply that a 16O-rich gaseous reservoir existed in the nebula until at least ∼0.7 Ma after the formation of the majority of CAIs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFM.H43A1216M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFM.H43A1216M"><span id="translatedtitle">Pore water dating by 129I: What do <span class="hlt">36</span><span class="hlt">Cl</span>/Cl ratio, dissolved 4He concentration, δ37Cl and 129I/127I ratio suggest in the Mobara Gas field, Japan?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mahara, Y.; Ohta, T.; Tokunaga, T.</p> <p>2010-12-01</p> <p>Total 24-brine samples were collected from hot springs and the Mobara gas wells in the Southern Kanto Gas field, where is not only the major production area for dissolved natural gas in Japan but for iodine in the world. Isotopic ratios of 129I/127I and <span class="hlt">36</span><span class="hlt">Cl</span>/Cl, and noble gases concentration dissolved into pore water were measured for estimating residence time of brine. Iodine concentration in brines increases from 10 mg/L in the northern Kanto plain to more than 100 mg/L in the south edge of the gas field, and finally reaches 170 mg/L. In contrast, the isotopic ratio of 129I/127I decreases 5×10-13 in north to 1.7×10-13 in south. Both distributions were presumably controlled by the thickness of the Kazusa group as natural gas reservoirs. The average 129I/127I ratio was estimated to be 2.33 ± 0.11×10-13 at the Mobara area. Average ages of brines are estimated to be 42 Ma by using the initial 129I/127I ratio (1.5×10-12), if the origin of 129I were cosmogenic. On the other hand, we deduced 0.2 - 0.9 Ma as the residence time of brine from comparison with the secular equilibrium <span class="hlt">36</span><span class="hlt">Cl</span>/Cl ratio (6.46 ± 2.24×10-15) for the reservoir formation of Pleistocene. The concentration of 4He dissolved in pore water in the bored rock core suggests that residence time of brines vertically ranges 0.12 - 1.05 Ma and it is also harmonized with the formation age (of 0.45 - 2.5 Ma). Furthermore, δ37Cl (- 0.14±0.13 ~ + 0.45±0.07 ‰) in pore water were measured under the chloride concentration increasing 5000 mg/L to 17000 mg/L at the depth from 642 m to 1902 m below the ground surface. The simulating analyses of δ37Cl was conducted under the boundary conditions of washing out by freshwater at the depth of 600 m below the ground surface, chloride concentration gradient of 17000/500 (mg/L/m) and diffusion alone without advection flow during the past 0.12 Ma. The fractionation factor for 35Cl and 37Cl was 1.0012 (Desauliniers et al., 1986). The analyses indicated that the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24909078','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24909078"><span id="translatedtitle">Biosynthesis of steroidal alkaloids in Solanaceae plants: incorporation of 3β-hydroxycholest-5-en-<span class="hlt">26</span>-<span class="hlt">al</span> into tomatine with tomato seedlings.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ohyama, Kiyoshi; Okawa, Akiko; Fujimoto, Yoshinori</p> <p>2014-08-01</p> <p>The C-26 amino group of tomatine, a representative Solanaceae steroidal alkaloid, is introduced in an early step of its biosynthesis from cholesterol. We recently proposed a transamination mechanism for the C-26 amination as opposed to the previously proposed mechanism involving a nitrogen nucleophilic displacement. In the present study, a deuterium labeled C-26 aldehyde, (24,24,27,27,27-(2)H5)-3β-hydroxycholest-5-en-<span class="hlt">26</span>-<span class="hlt">al</span>, was synthesized and fed to a tomato (Solanum lycopersicum) seedling. LC-MS analysis of the biosynthesized tomatine indicated that the labeled aldehyde was incorporated into tomatine. The finding strongly supports the intermediacy of the aldehyde and the transamination mechanism during C-26 amination.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/20863727','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/20863727"><span id="translatedtitle">Measurements of the {sup 25}Mg({sup 11}B,{sup 12}C){sup 24}Na and {sup 25}Mg({sup 11}B,{sup 10}Be){sup <span class="hlt">26</span>}<span class="hlt">Al</span> proton transfer reactions</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Faria, P. N. de; Lichtenthaeler, R.; Guimaraes, V.; Lepine-Szily, A.; Benjamim, E. A.; Lima, G. F.; Moro, A. M.</p> <p>2006-08-15</p> <p>Angular distributions for the {sup 11}B+{sup 25}Mg elastic scattering, {sup 25}Mg({sup 11}B,{sup 12}C){sup 24}Na proton pickup, and {sup 25}Mg({sup 11}B,{sup 10}Be){sup <span class="hlt">26</span>}<span class="hlt">Al</span> stripping reactions have been measured at E{sub {sup 11}B}=35 MeV. The angular distributions have been analyzed by the distorted-waves Born approximation calculations using the code fresco. The spectroscopic factors for the overlaps <{sup 25}Mg|{sup <span class="hlt">26</span>}<span class="hlt">Al</span>>,<{sup 25}Mg|{sup 24}Na> for the ground state and excited states of {sup <span class="hlt">26</span>}<span class="hlt">Al</span> and {sup 24}Na have been obtained and compared to previous measurements and shell-model calculations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.C51B0694S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.C51B0694S"><span id="translatedtitle">Deciphering the Glacial-Interglacial Landscape History in Greenland Based on Markov Chain Monte Carlo Inversion of Existing 10Be-<span class="hlt">26</span><span class="hlt">Al</span> Data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Strunk, A.; Knudsen, M. F.; Larsen, N. K.; Egholm, D. L.; Jacobsen, B. H.</p> <p>2015-12-01</p> <p>Surface exposure dating with cosmogenic nuclides is a dating method under continuous development. It is particularly useful for dating ice-sheet fluctuations in glacial environments, which is essential to increase our understanding of past climate fluctuations and glacial dynamics. Constraining the landscape history in previously glaciated terrains may be difficult, however, due to unknown erosion rates and the presence of inherited nuclides. The potential use of cosmogenic nuclides in landscapes with a complex history of exposure and erosion is therefore often quite limited. In this study, we investigate the landscape history in eastern and western Greenland by applying a novel Markov Chain Monte Carlo (MCMC) inversion approach to the existing 10Be-<span class="hlt">26</span><span class="hlt">Al</span> data from these regions. The new MCMC approach allows us to constrain the most likely landscape history based on comparisons between simulated and measured cosmogenic nuclide concentrations. It is a fundamental assumption of the model approach that the exposure history at the site/location can be divided into two distinct regimes: i) interglacial periods characterized by zero shielding due to overlying ice and a uniform interglacial erosion rate, and ii) glacial periods characterized by 100 % shielding and a uniform glacial erosion rate. We incorporate the exposure/burial history in the model framework by applying a threshold value to the global marine benthic d18O record and include the threshold value as a free model parameter, hereby taking into account global changes in climate. The other free parameters include the glacial and interglacial erosion rates as well as the timing of the Holocene deglaciation. The model essentially simulates numerous different landscape scenarios based on these four parameters and zooms in on the most plausible combination of model parameters. Here, we apply the MCMC-model to the concentrations of 10Be and <span class="hlt">26</span><span class="hlt">Al</span> measured in three previous studies of glacial fluctuations in Greenland</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/352651','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/352651"><span id="translatedtitle">Quantifying denudation rates on inselbergs in the central Namib Desert using in situ-produced cosmogenic {sup 10}Be and {sup <span class="hlt">26</span>}<span class="hlt">Al</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Cockburn, H.A.P.; Summerfield, M.A.; Seidl, M.A.</p> <p>1999-05-01</p> <p>In situ-produced cosmogenic isotope concentrations in bedrock surfaces provide valuable estimates of site-specific, long-term rates of denudation and provide constraints for numerical landscape-evolution models. Measurements of cosmogenic {sup 10}Be and {sup <span class="hlt">26</span>}<span class="hlt">Al</span> from graphite inselbergs in the arid to hyperarid central Namib Desert, Namibia, indicate a mean rate of summit lowering of 5.07 {+-} 1.1 m/m.y. over the past {ge} 10{sup 5} yr. The persistence of an arid climate in the region suggests that a similar rate may have prevailed for the past {approximately} 10 m.y. and possibly throughout much of the Cenozoic. Some samples have complex exposure histories that can be explained by the mode of inselberg weathering and mass wasting. The denudation rates estimated here are an order of magnitude higher than those reported for inselbergs in a significantly more humid environment in South Australia. This difference may largely be due to active salt weathering in the central Namib as a result of high levels of coastal fog precipitation.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_10 --> <div id="page_11" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="201"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/902293','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/902293"><span id="translatedtitle">Long-term slip rate of the southern San Andreas Fault, from 10Be-<span class="hlt">26</span><span class="hlt">Al</span> surface exposure dating of an offset alluvial fan</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>der Woerd, J v; Klinger, Y; Sieh, K; Tapponnier, P; Ryerson, F; M?riaux, A</p> <p>2006-01-13</p> <p>We determine the long-term slip rate of the southern San Andreas Fault in the southeastern Indio Hills using {sup 10}Be and {sup <span class="hlt">26</span>}<span class="hlt">Al</span> isotopes to date an offset alluvial fan surface. Field mapping complemented with topographic data, air photos and satellite images allow to precisely determine piercing points across the fault zone that are used to measure an offset of 565 {+-} 80 m. A total of twenty-six quartz-rich cobbles from three different fan surfaces were collected and dated. The tight cluster of nuclide concentrations from 19 samples out of 20 from the offset fan surface implies a simple exposure history, negligible prior exposure and erosion, and yield an age of 35.5 {+-} 2.5 ka. The long-term slip rate of the San Andreas Fault south of Biskra Palms is thus 15.9 {+-} 3.4 mm/yr. This rate is about 10 mm/yr slower than geological (0-14 ka) and short-term geodetic estimates for this part of the San Andreas Fault implying changes in slip rate or in faulting behavior. This result puts new constraints on the slip rate of the San Jacinto and on the Eastern California Shear Zone for the last 35 ka. Our study shows that more sites along the major faults of southern California need to be targeted to better constrain the slip-rates over different time scales.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/pages/biblio/1235049-measurements-production-cross-sections-gev-mev-proton-bombardment-natcu-targets','SCIGOV-DOEP'); return false;" href="http://www.osti.gov/pages/biblio/1235049-measurements-production-cross-sections-gev-mev-proton-bombardment-natcu-targets"><span id="translatedtitle">Measurements of production cross sections of 10Be and <span class="hlt">26</span><span class="hlt">Al</span> by 120 GeV and 392 MeV proton bombardment of 89Y, 159Tb, and natCu targets</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Sekimoto, S.; Okumura, S.; Yashima, H.; Matsushi, Y.; Matsuzaki, H.; Matsumura, H.; Toyoda, A.; Oishi, K.; Matsuda, N.; Kasugai, Y.; et al</p> <p>2015-08-12</p> <p>The production cross sections of 10Be and <span class="hlt">26</span><span class="hlt">Al</span> were measured by accelerator mass spectrometry using 89Y, 159Tb, and natCu targets bombarded by protons with energies Ep of 120 GeV and 392 MeV. The production cross sections obtained for 10Be and <span class="hlt">26</span><span class="hlt">Al</span> were compared with those previously reported using Ep = 50 MeV–24 GeV and various targets. It was found that the production cross sections of 10Be monotonically increased with increasing target mass number when the proton energy was greater than a few GeV. On the other hand, it was also found that the production cross sections of 10Be decreased asmore » the target mass number increased from that of carbon to those near the mass numbers of nickel and zinc when the proton energy was below approximately 1 GeV. They also increased as the target mass number increased from near those of nickel and zinc to that of bismuth, in the same proton energy range. Similar results were observed in the production cross sections of <span class="hlt">26</span><span class="hlt">Al</span>, though the absolute values were quite different between 10Be and <span class="hlt">26</span><span class="hlt">Al</span>. As a result, the difference between these production cross sections may depend on the impact parameter (nuclear radius) and/or the target nucleus stiffness.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1814508R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1814508R"><span id="translatedtitle">Potentials and pitfalls of depth profile (10Be), burial isochron (<span class="hlt">26</span><span class="hlt">Al</span>/10Be) and palaeomagnetic techniques for dating Early Pleistocene terrace deposits of the Moselle valley (Germany)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rixhon, Gilles; Cordier, Stéphane; May, Simon Matthias; Kelterbaum, Daniel; Szemkus, Nina; Keulertz, Rebecca; Dunai, Tibor; Binnie, Steven; Hambach, Ulrich; Scheidt, Stephanie; Brueckner, Helmut</p> <p>2016-04-01</p> <p>Throughout the river network of the Rhenish Massif the so-called main terraces complex (MTC) forms the morphological transition between a wide upper palaeovalley and a deeply incised lower valley. The youngest level of this complex (YMT), directly located at the edge of the incised valley, represents a dominant geomorphic feature; it is often used as a reference level to identify the beginning of the main middle Pleistocene incision episode (Demoulin & Hallot, 2009). Although the main terraces are particularly well preserved in the lower Moselle valley, a questionable age of ca. 800 ka is assumed for the YMT, mainly based on the uncertain extrapolation of controversially interpreted palaeomagnetic data obtained in the Rhine valley. In this study, we applied terrestrial cosmogenic nuclide (TCN) dating (10Be/<span class="hlt">26</span><span class="hlt">Al</span>) and palaeomagnetic dating to Moselle fluvial sediments of the MTC. To unravel the spatio-temporal characteristics of the Pleistocene evolution of the valley, several sites along the lower Moselle were sampled following two distinct TCN dating strategies: depth profiles where the original terrace (palaeo-) surface is well preserved and did not experience a major post-depositional burial (e.g., loess cover); and the isochron technique, where the sediment thickness exceeds 4.5-5 m. One terrace deposit was sampled for both approaches (reference site). In addition, palaeomagnetic sampling was systematically performed in each terrace sampled for TCN measurements. The TCN dating techniques show contrasting results for our reference site. Three main issues are observed for the depth profile method: (i) an inability of the modeled profile to constrain the 10Be concentration of the uppermost sample; (ii) an overestimated density value as model output; and (iii) a probable concentration steady state of the terrace deposits. By contrast, the isochron method yields a burial age estimate of 1.26 +0.29/-0.25 Ma, although one sample showed a depleted <span class="hlt">26</span><span class="hlt">Al</span>/10Be ratio</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014EGUGA..16.8081R&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014EGUGA..16.8081R&link_type=ABSTRACT"><span id="translatedtitle">Unraveling the Quaternary river incision in the Moselle valley (Rhenish Massif, Germany): new insights from cosmogenic nuclide dating (10Be/<span class="hlt">26</span><span class="hlt">Al</span>) of the Main Terrace complex</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rixhon, Gilles; Cordier, Stéphane; Harmand, Dominique; May, Simon Matthias; Kelterbaum, Daniel; Dunai, Tibor; Binnie, Steven; Brückner, Helmut</p> <p>2014-05-01</p> <p>Throughout the whole river network of the Rhenish Massif, the terrace complex of the so-called Main Terrace forms the morphological transition between a wide upper palaeovalley (plateau valley) and a deeply incised lower valley. The youngest level of this Main Terrace complex (YMT), directly located at the edge of the incised valley, represents a dominant geomorphic feature in the terrace flight; it is often used as a reference level to identify the start of the main middle Pleistocene incision episode (Demoulin & Hallot, 2009). The latter probably reflects the major tectonic pulse that affected the whole Massif and was related to an acceleration of the uplift rates (Demoulin & Hallot, 2009). The Main terraces are particularly well preserved in the lower Moselle valley and are characterized by a constant absolute elevation of their base along a 150 km-long reach. Despite that various hypotheses have been proposed to explain this horizontality (updoming, faulting...), all studies assumed an age of ca. 800 ka for the YMT, mainly based on the questionable extrapolation of palaeomagnetic data obtained in the Rhine valley. Therefore, a reliable chronological framework is still required to unravel the spatio-temporal characteristics of the Pleistocene evolution of the Moselle valley. In this study, we apply cosmogenic nuclide dating (10Be/<span class="hlt">26</span><span class="hlt">Al</span>) to fluvial sediments pertaining to the Main Terrace complex or to the upper Middle Terraces. Several sites along the lower Moselle were sampled following two distinct sampling strategies: (i) depth profiles where the original terrace (palaeo-)surface is well preserved and did not experience much postdepositional burial (e.g., loess cover); and (ii) the isochron technique where the sediment thickness exceeds 3 m. Cosmogenic nuclide ages recently obtained for three rivers in the Meuse catchment in the western Rhenish Massif demonstrated that the Main Terraces were younger than expected and their abandonment was diachronic along the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002Geomo..45...89C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002Geomo..45...89C"><span id="translatedtitle">Using 10Be and <span class="hlt">26</span><span class="hlt">Al</span> to determine sediment generation rates and identify sediment source areas in an arid region drainage basin</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Clapp, Erik M.; Bierman, Paul R.; Caffee, Marc</p> <p>2002-06-01</p> <p>We measured 10Be and <span class="hlt">26</span><span class="hlt">Al</span> in 64 sediment and bedrock samples collected throughout the arid, 187 km 2 Yuma Wash drainage basin, southwestern Arizona. From the measurements, we determine long-term, time-integrated rates of upland sediment generation (81±5 g m -2 year -1) and bedrock equivalent lowering (30±2 m Ma -1) consistent with other estimates for regions of similar climate, lithology, and topography. In a small (˜8 km 2), upland sub-basin, differences in nuclide concentrations between bedrock outcrops and hillslope colluvium suggest weathering of bedrock beneath a colluvial cover is a more significant source of sediment (40×10 4 kg year -1) than weathering of exposed bedrock surfaces (10×10 4 kg year -1). Mixing models constructed from nuclide concentrations of sediment reservoirs identify important sediment source areas. Hillslope colluvium is the dominant sediment source to the upper reaches of the sub-basin channel; channel cutting of alluvial terraces is the dominant source in the lower reaches. Similarities in nuclide concentrations of various sediment reservoirs indicate short sediment storage times (<10 3 years). Nuclide concentrations, measured in channel sediment from tributaries of Yuma Wash and in samples collected along the length of the Wash, were used to construct mixing models and determine sediment sources to the main stem channel. We find an exponential decrease in the channel nuclide concentrations with distance downstream, suggesting that as much as 40% of sediment discharged from Yuma Wash has been recycled from storage within basin fill alluvium. Sediment generation and denudation rates determined from the main stem are greater (25%) than rates determined from upland sub-basins suggesting that, currently, sediment may be exported from the basin more quickly than it is being generated in the uplands. Independence of nuclide concentration and sediment grain size indicates that channels transport sediment in discrete pulses before rapidly</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.2925F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.2925F"><span id="translatedtitle">Deglaciation of Antarctica since the Last Glacial Maximum - what can we learn from cosmogenic 10Be and <span class="hlt">26</span><span class="hlt">Al</span> exposure ages?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fink, David</p> <p>2015-04-01</p> <p>Ice volume changes at the coastal margins of Antarctica during the global LGM are uncertain. The little evidence available suggests that behaviour of the East and West Antarctic Ice Sheets are markedly different and complex. It is hypothesised that during interglacials, thinning of the Ross Ice Shelf, a more open-water environment and increased precipitation, allowed outlet glaciers draining the Transantarctic Mnts and fed by interior Ice Sheets to advance during moist warmer periods, out of phase with colder arid periods. In contrast, glacier dynamics along the vast coastal perimeter of East Antarctica is strongly influenced by Southern Ocean conditions. Cosmogenic 10Be and <span class="hlt">26</span><span class="hlt">Al</span> chronologies, although restricted to ice-free oasis and mountains flanking drainage glaciers, has become an invaluable, if not unique, tool to quantify spatial and temporal Pleistocene ice sheet variability over the past 2 Ma. Despite an increasing number of well documented areas, extracting reliable ages from glacial deposits in polar regions is problematic. Recycling of previously exposed/ buried debris and continual post-depositional modification leads to age ambiguities for a coeval glacial landform. More importantly, passage of cold-based ice can leave a landform unmodified resulting in young erratics deposited on ancient bedrock. Advances in delivering in-situ radiocarbon to routine application offer some relief. Exposure ages from different localities throughout East Antarctica (Framnes Mnts, Lutzow-Holm Bay, Vestfold Hills) and West Antarctica (Denton Ranges, Hatherton Glacier, Shackleton Range) highlight some of the new findings. This talk presents results which quantify the magnitude and timing of paleo-ice sheet thickness changes, questions the validity of an Antarctic LGM and discusses the complexities encountered in the often excessive spread in exposure ages.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1992Metic..27Q.244K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1992Metic..27Q.244K"><span id="translatedtitle">Roter Kamm Impact Crater, Namibia: Age Constraints from K-Ar, Rb-Sr, Fission Track, 10Be-<span class="hlt">26</span><span class="hlt">Al</span> Studies</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Koeberl, C.; Klein, J.; Matsuda, J.; Nagao, K.; Reimold, W. U.; Storzer, D.</p> <p>1992-07-01</p> <p>INTRODUCTION. The Roter Kamm impact crater is located in the Namib Desert in Namibia. The impact occurred in Precambrian granitic-granodioritic orthogneisses of the 1200-900-Ma-old Namaqualand Metamorphic Complex. The granites are invaded by quartz veins and quartz-feldspar-pegmatites. Gariep metasediments probably overlaid the Namaqualand complex at the time of the impact (Reimold and Miller, 1989). Previous estimates for the crater age are not well constrained: regional geology suggests an age of 5-10 Ma, while the only available ^40Ar-^39Ar age (Hartung et al., 1991) is 3.7 Ma. Fission tracks measured in apatites from granites found on or near the crater rim were not completely reset by the impact and suggest an uplift event around 20 Ma ago (Storzer et al., 1990). We are using several approaches to bracket the age of the crater: we have measured melt breccia and pseudotachylite K-Ar ages, and apatite fission track ages in several rim granites. We are comparing Rb-Sr isotope data for rim granites with known ages of regional resetting events (Allsopp et al., 1979). Finally, we are using ^10Be-^<span class="hlt">26</span><span class="hlt">Al</span> measured by accelerator mass spectrometry to determine surface exposure ages for quartz excavated during the impact event. RESULTS AND DISCUSSION. The target rock composition and stratigraphy at Roter Kamm is relatively complicated. Melt breccias formed from pegmatites, gneisses, or schists, while pseudotachylites probably formed from gneissic basement or quartz-feldspar-pegmatites (Reimold and Miller, 1989). Whole rock Rb-Sr data for several granites yield 1498 Ma, and mineral separates from sample URK-M indicate an "age" of 466 Ma; these ages are similar to those of country rocks from the general area of the northwestern Cape/southern Namibia (Allsopp et al., 1979) which indicate two widespread regional resetting events at ca. 700 Ma (related to the Pan-African orogenic deformation), and ca. 500 Ma, related to a subsequent metamorphic event. For K-Ar ages, we</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeCoA.189...70K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeCoA.189...70K"><span id="translatedtitle">A link between oxygen, calcium and titanium isotopes in <span class="hlt">26</span><span class="hlt">Al</span>-poor hibonite-rich CAIs from Murchison and implications for the heterogeneity of dust reservoirs in the solar nebula</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kööp, Levke; Davis, Andrew M.; Nakashima, Daisuke; Park, Changkun; Krot, Alexander N.; Nagashima, Kazuhide; Tenner, Travis J.; Heck, Philipp R.; Kita, Noriko T.</p> <p>2016-09-01</p> <p>PLACs (platy hibonite crystals) and related hibonite-rich calcium-, aluminum-rich inclusions (CAIs; hereafter collectively referred to as PLAC-like CAIs) have the largest nucleosynthetic isotope anomalies of all materials believed to have formed in the solar system. Most PLAC-like CAIs have low inferred initial <span class="hlt">26</span><span class="hlt">Al</span>/27Al ratios and could have formed prior to injection or widespread distribution of <span class="hlt">26</span><span class="hlt">Al</span> in the solar nebula. In this study, we report <span class="hlt">26</span><span class="hlt">Al</span>-26Mg systematics combined with oxygen, calcium, and titanium isotopic compositions for a large number of newly separated PLAC-like CAIs from the Murchison CM2 chondrite (32 CAIs studied for oxygen, 26 of these also for <span class="hlt">26</span><span class="hlt">Al</span>-26Mg, calcium and titanium). Our results confirm (1) the large range of nucleosynthetic anomalies in 50Ti and 48Ca (our data range from -70‰ to +170‰ and -60‰ to +80‰, respectively), (2) the substantial range of Δ17O values (-28‰ to -17‰, with Δ17O = δ17O - 0.52 × δ18O), and (3) general <span class="hlt">26</span><span class="hlt">Al</span>-depletion in PLAC-like CAIs. The multielement approach reveals a relationship between Δ17O and the degree of variability in 50Ti and 48Ca: PLAC-like CAIs with the highest Δ17O (∼-17‰) show large positive and negative 50Ti and 48Ca anomalies, while those with the lowest Δ17O (∼-28‰) have small to no anomalies in 50Ti and 48Ca. These observations could suggest a physical link between anomalous 48Ca and 50Ti carriers and an 16O-poor reservoir. We suggest that the solar nebula was isotopically heterogeneous shortly after collapse of the protosolar molecular cloud, and that the primordial dust reservoir, in which anomalous carrier phases were heterogeneously distributed, was 16O-poor (Δ17O ⩾ -17‰) relative to the primordial gaseous (CO + H2O) reservoir (Δ17O < -35‰). However, other models such as CO self-shielding in the protoplanetary disk are also considered to explain the link between oxygen and calcium and titanium isotopes in PLAC-like CAIs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70030794','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70030794"><span id="translatedtitle">Cosmogenic 10Be and <span class="hlt">26</span><span class="hlt">Al</span> exposure ages of tors and erratics, Cairngorm Mountains, Scotland: Timescales for the development of a classic landscape of selective linear glacial erosion</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Phillips, W.M.; Hall, A.M.; Mottram, R.; Fifield, L.K.; Sugden, D.E.</p> <p>2006-01-01</p> <p>The occurrence of tors within glaciated regions has been widely cited as evidence for the preservation of relic pre-Quaternary landscapes beneath protective covers of non-erosive dry-based ice. Here, we test for the preservation of pre-Quaternary landscapes with cosmogenic surface exposure dating of tors. Numerous granite tors are present on summit plateaus in the Cairngorm Mountains of Scotland where they were covered by local ice caps many times during the Pleistocene. Cosmogenic 10Be and <span class="hlt">26</span><span class="hlt">Al</span> data together with geomorphic relationships reveal that these landforms are more dynamic and younger than previously suspected. Many Cairngorm tors have been bulldozed and toppled along horizontal joints by ice motion, leaving event surfaces on tor remnants and erratics that can be dated with cosmogenic nuclides. As the surfaces have been subject to episodic burial by ice, an exposure model based upon ice and marine sediment core proxies for local glacial cover is necessary to interpret the cosmogenic nuclide data. Exposure ages and weathering characteristics of tors are closely correlated. Glacially modified tors and boulder erratics with slightly weathered surfaces have 10Be exposure ages of about 15 to 43 ka. Nuclide inheritance is present in many of these surfaces. Correction for inheritance indicates that the eastern Cairngorms were deglaciated at 15.6 ?? 0.9 ka. Glacially modified tors with moderate to advanced weathering features have 10Be exposure ages of 19 to 92 ka. These surfaces were only slightly modified during the last glacial cycle and gained much of their exposure during the interstadial of marine Oxygen Isotope Stage 5 or earlier. Tors lacking evidence of glacial modification and exhibiting advanced weathering have 10Be exposure ages between 52 and 297 ka. Nuclide concentrations in these surfaces are probably controlled by bedrock erosion rates instead of discrete glacial events. Maximum erosion rates estimated from 10Be range from 2.8 to 12.0 mm/ka, with</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/15011576','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/15011576"><span id="translatedtitle">Neuroscience and Accelerator Mass Spectrometry</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Palmblad, M N; Buchholz, B A; Hillegonds, D J; Vogel, J S</p> <p>2004-08-02</p> <p>Accelerator mass spectrometry (AMS) is a mass spectrometric method for quantifying rare isotopes. It has had great impact in geochronology and archaeology and is now being applied in biomedicine. AMS measures radioisotopes such as {sup 3}H, {sup 14}C, {sup <span class="hlt">26</span>}<span class="hlt">Al</span>, {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> and {sup <span class="hlt">41</span>}<span class="hlt">Ca</span>, with zepto- or attomole sensitivity and high precision and throughput, enabling safe human pharmacokinetic studies involving: microgram doses, agents having low bioavailability, or toxicology studies where administered doses must be kept low (<1 {micro}g/kg). It is used to study long-term pharmacokinetics, to identify biomolecular interactions, to determine chronic and low-dose effects or molecular targets of neurotoxic substances, to quantify transport across the blood-brain barrier and to resolve molecular turnover rates in the human brain on the timescale of decades. We will here review how AMS is applied in neurotoxicology and neuroscience.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/10114774','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/10114774"><span id="translatedtitle">Production rates of terrestrial in-situ-produced cosmogenic nuclides</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Reedy, R.C.; Tuniz, C.; Fink, D.</p> <p>1993-12-31</p> <p>Production rates of cosmogenic nuclides made in situ in terrestrial samples and how they are applied to the interpretation of measured radionuclide concentrations were discussed at a one-day Workshop held 2 October 1993 in Sydney, Australia. The status of terrestrial in-situ studies using the long-lived radionuclides {sup 10}Be, {sup 14}C, {sup <span class="hlt">26</span>}<span class="hlt">Al</span>, {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>, and {sup <span class="hlt">41</span>}<span class="hlt">Ca</span> and of various modeling and related studies were presented. The relative uncertainties in the various factors that go into the interpretation of these terrestrial in-situ cosmogenic nuclides were discussed. The magnitudes of the errors for these factors were estimated and none dominated the final uncertainty.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4350738','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4350738"><span id="translatedtitle">Synthèse et structure cristalline d’un matériau noir AgMnII 3(MnIII 0,<span class="hlt">26</span><span class="hlt">Al</span>0,74)(MoO4)5</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Bouzidi, Chahira; Frigui, Wafa; Zid, Mohamed Faouzi</p> <p>2015-01-01</p> <p>A new silver aluminium trimangan­ese penta­molybdate {silver(I) trimanganese(II) aluminium penta­kis­[tetra­oxidomolybdate(VI)]}, AgMnII 3(MnIII 0,<span class="hlt">26</span><span class="hlt">Al</span>0,74)(MoO4)5, has been synthesized using solid-state methods. The structure is composed of M 2O10 dimers, M 3O14 (M = Mn, Al) trimers and MoO4 tetra­hedra sharing corners and forming three types of layers A, B and B′. The sequence of the constituting layers is A–BB′–A–BB′, with B′ obtained from B by inversion symmetry, forming a three-dimensional structure with large channels in which the positionally disordered and partially occupied Ag+ ions reside. The MnIII and AlIII atoms share the same site, M. AgMnII 3(MnIII 0,<span class="hlt">26</span><span class="hlt">Al</span>0,74)(MoO4)5 is isotypic with the NaMg3 X(MoO4)5 (X = Al, In) family and with NaFe4(MoO4)5. A comparative structural description is provided between the structure of the title compound and those of related phases containing dimers, trimers and tetra­mers. PMID:25844193</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004M%26PS...39..481W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004M%26PS...39..481W"><span id="translatedtitle">Exposure history and terrestrial ages of ordinary chondrites from the Dar al Gani region, Libya</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Welten, K. C.; Nishiizumi, K.; Finkel, R. C.; Hillegonds, D. J.; Jull, A. J. T.; Franke, L.; Schultz, L.</p> <p>2004-03-01</p> <p>We measured the concentrations of noble gases in 32 ordinary chondrites from the Dar al Gani (DaG) region, Libya, as well as concentrations of the cosmogenic radionuclides 14C, 10Be, <span class="hlt">26</span><span class="hlt">Al</span>, <span class="hlt">36</span><span class="hlt">Cl</span>, and <span class="hlt">41</span><span class="hlt">Ca</span> in 18 of these samples. Although the trapped noble gases in five DaG samples show ratios typical of solar or planetary gases, in all other DaG samples, they are dominated by atmospheric contamination, which increases with the degree of weathering. Cosmic ray exposure (CRE) ages of DaG chondrites range from ~1 Myr to 53 Myr. The CRE age distribution of 10 DaG L chondrites shows a cluster around 40 Myr due to four members of a large L6 chondrite shower. The CRE age distribution of 19 DaG H chondrites shows only three ages coinciding with the main H chondrite peak at ~7 Myr, while seven ages are <5 Myr. Two of these H chondrites with short CRE ages (DaG 904 and 908) show evidence of a complex exposure history. Five of the H chondrites show evidence of high shielding conditions, including low 22Ne/21Ne ratios and large contributions of neutron-capture <span class="hlt">36</span><span class="hlt">Cl</span> and <span class="hlt">41</span><span class="hlt">Ca</span>. These samples represent fragments of two or more large pre-atmospheric objects, which supports the hypothesis that the high H/L chondrite ratio at DaG is due to one or more large unrecognized showers. The 14C concentrations correspond to terrestrial ages <35 kyr, similar to terrestrial ages of chondrites from other regions in the Sahara but younger than two DaG achondrites. Despite the loss of cosmogenic <span class="hlt">36</span><span class="hlt">Cl</span> and <span class="hlt">41</span><span class="hlt">Ca</span> during oxidation of metal and troilite, concentrations of <span class="hlt">36</span><span class="hlt">Cl</span> and <span class="hlt">41</span><span class="hlt">Ca</span> in the silicates are also consistent with 14C ages <35 kyr. The only exception is DaG 343 (H4), which has a <span class="hlt">41</span><span class="hlt">Ca</span> terrestrial age of 150 ± 40 kyr. This old age shows that not only iron meteorites and achondrites but also chondrites can survive the hot desert environment for more than 50 kyr. A possible explanation is that older meteorites were covered by soils during wetter periods and were recently exhumed by removal of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22267765','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22267765"><span id="translatedtitle">Use of Arrott plots to identify Néel temperature (T{sub N}) in metamagnetic Ni{sub 48}Co{sub 6}Mn{sub <span class="hlt">26</span>}<span class="hlt">Al</span>{sub 20} polycrystalline ribbons</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Singh, Rohit; Kumar Srivastava, Saurabh; Chatterjee, Ratnamala E-mail: rmala@physics.iitd.ac.in; Nigam, Arun K.; Khovaylo, Vladimir V.; Varga, Lajos K.</p> <p>2013-12-28</p> <p>(Ni{sub 48}Co{sub 6})Mn{sub <span class="hlt">26</span>}<span class="hlt">Al</span>{sub 20} polycrystalline ribbons with B2 structure at room temperature are investigated. Considering the presence of competing magnetic interactions, Arrott-plot analysis gives T{sub N} ∼ 170 K. A broad ferromagnetic-paramagnetic transition (T{sub C}) is observed at ∼200 K. H-T phase-diagram is used to validate the presence of competing exchange interactions that persist till very close to T{sub C}. Based on Néel theory, a cluster model is used to explain the presence of ferromagnetic and antiferromagnetic clusters in the sample. Formation of ferromagnetic clusters can be understood in terms of positive exchange interactions among the Mn atoms that are neighboring Co atoms located at Ni sites.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001ApJ...549.1151G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001ApJ...549.1151G"><span id="translatedtitle">Did Solar Energetic Particles Produce the Short-lived Nuclides Present in the Early Solar System?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Goswami, J. N.; Marhas, K. K.; Sahijpal, S.</p> <p>2001-03-01</p> <p>Production of the short-lived nuclides <span class="hlt">41</span><span class="hlt">Ca</span>, <span class="hlt">36</span><span class="hlt">Cl</span>, <span class="hlt">26</span><span class="hlt">Al</span>, and 53Mn by solar energetic particles (SEP) interacting with dust grains of chondritic (=solar) composition is estimated considering a broad range of spectral parameters for the SEP and appropriate nuclear reaction cross sections. The dust grains are assumed to follow a power-law size distribution and to range in size from 10 μm to 1 cm. The possibility that an enhanced flux of SEP from an active early (T Tauri) Sun could have been responsible for the production of these short-lived nuclides in the early solar system is investigated. SEP production of <span class="hlt">41</span><span class="hlt">Ca</span> and <span class="hlt">36</span><span class="hlt">Cl</span> will match their abundances in the early solar system inferred from meteorite data if the SEP irradiation duration was ~5×105-106 yr and the SEP flux was higher by a factor of more than 5×103 than the contemporary long-term averaged value of Nproton (E>10 MeV)~100 cm-2 s-1. However, corresponding production of <span class="hlt">26</span><span class="hlt">Al</span> will be much below the level needed to match its inferred abundance in the early solar system. SEP production, therefore, fails to explain the observed correlated presence of <span class="hlt">41</span><span class="hlt">Ca</span> and <span class="hlt">26</span><span class="hlt">Al</span> with canonical initial abundances in early solar system solids. The abundance of 53Mn in the early solar system is not tightly constrained by the meteorite data, and the various estimates differ by a factor of 5. Coproduction of <span class="hlt">41</span><span class="hlt">Ca</span>, <span class="hlt">36</span><span class="hlt">Cl</span>, and 53Mn that will match the meteorite data for the higher initial abundance of 53Mn is possible if the SEP irradiation persisted for about a million years or more with a flux enhancement factor of ~5000-10,000. On the other hand, the lower initial value of 53Mn can also be matched by a flux enhancement factor of ~1000 and an irradiation duration of a few million years; the corresponding production of the other nuclides will be <=10% of the level needed to match their abundances in the early solar system. Target abundance consideration rules out the possibility of SEP production of 60Fe, another short</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016E%26PSL.452..258W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016E%26PSL.452..258W"><span id="translatedtitle">The cosmogenic record of mountain erosion transmitted across a foreland basin: Source-to-sink analysis of in situ10Be, <span class="hlt">26</span><span class="hlt">Al</span> and 21Ne in sediment of the Po river catchment</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wittmann, Hella; Malusà, Marco G.; Resentini, Alberto; Garzanti, Eduardo; Niedermann, Samuel</p> <p>2016-10-01</p> <p>We analyze the source-to-sink variations of in situ10Be, <span class="hlt">26</span><span class="hlt">Al</span> and 21Ne concentrations in modern sediment of the Po river catchment, from Alpine, Apennine, floodplain, and delta samples, in order to investigate how the cosmogenic record of orogenic erosion is transmitted across a fast-subsiding foreland basin. The in situ10Be concentrations in the analyzed samples range from ∼ 0.8 ×104 at /gQTZ to ∼ 6.5 ×104 at /gQTZ. The 10Be-derived denudation rates range from 0.1 to 1.5 mm/yr in the Alpine source areas and from 0.3 to 0.5 mm/yr in the Apenninic source areas. The highest 10Be-derived denudation rates are found in the western Central Alps (1.5 mm/yr). From these data, we constrain a sediment flux leaving the Alpine and the Apenninic source areas (>27 Mt/yr and ca. 5 Mt/yr, respectively) that is notably higher than the estimates of sediment export provided by gauging (∼10 Mt/yr at the Po delta). We observe a high variability in 10Be concentrations and 10Be-derived denudation rates in the source areas. In the Po Plain, little variability is observed, and at the same time, the area-weighed 10Be concentration of (2.29 ± 1.57) ×104 at /gQTZ (±1 SD of the dataset) from both the Alps and the Apennines is poorly modified (by tributary input) in sediment of the Po Plain ((2.68 ± 0.78 , ± 1 SD) ×104 at /gQTZ). The buffering effect of the Po floodplain largely removes scatter in 10Be signals. We test for several potential perturbations of the cosmogenic nuclide record during source to sink transfer in the Po basin. We find that sediment trapping in deep glacial lakes or behind dams does not significantly change the 10Be-mountain record. For example, similar 10Be concentrations are measured upstream and downstream of the postglacial Lake Maggiore, suggesting that denudation rates prior to lake formation were similar to today's. On the scale of the entire basin, the 10Be concentration of basins with major dams is similar to those without major dams. A potential</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001AGUFM.S52D0673V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001AGUFM.S52D0673V"><span id="translatedtitle">First Long-Term slip-Rate Along the San Andreas Fault Based on 10Be-<span class="hlt">26</span><span class="hlt">Al</span> Surface Exposure Dating : The Biskra Palms Site, 23 mm/yr for the last 30,000 years.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>van der Woerd, J.; Klinger, Y.; Sieh, K.; Tapponnier, P.; Ryerson, F.</p> <p>2001-12-01</p> <p>Slip-rate along the San Andreas fault is known precisely at only two locations : at Wallace Creek, 34 +/- 3 mm/yr for the past 13,500 yrs and at Cajon Creek, 24.5+/- 3 mm/yr for the past 14,500 yrs. When compared to the long-term and far-field plate motion, these rates provide important constraint on how and where strain is accommodated across the plate boundary. Here we present a new determination of the slip-rate along the San Andreas Fault at Biskra Palms, based on 10Be-<span class="hlt">26</span><span class="hlt">Al</span> surface exposure dating. The studied area is located southeast of the San Gorgonio restraining bend, a complex section of the fault which has not produced a large earthquake in historical time. At Biskra Palms, the San Andreas Fault offsets an alluvial fan (T2) about 700 m. Keller et al. (1982) recognized the importance of this site and estimated the age of the offset fan surfaces based on degree of soil development between 20 and 70 kyrs, providing a very loosely constraint slip-rate between 10 and 35 mm/yr. We have analyzed 21 quartz rich cobbles from the surface of the fan, upstream, downstream and within the fault zone. 10Be and <span class="hlt">26</span><span class="hlt">Al</span> measurements yield consistent results implying simple exposure at the surface. 7 samples collected on the T2 fan surface downstream yield an average exposure age of 30.7 +/- 2.1 kyrs. The tight cluster of these ages indicate no or minor pre-exposition during transport in the small catchment upstream. 7 samples from T2 upstream from the fault yield an average exposure age of 29.5 +/- 2.8 kyrs. One additional sample of this surface (38.4+/-3.6 kyrs) is older than the others and may have been pre-exposed before deposition on the fan. 2 samples from a T2 remnant within the fault zone yield an average age of 29.6 +/- 2.6 kyrs. 4 additional samples were collected from two smaller alluvial surfaces (T3 and T4) remnant found only upstream from the fault zone and yield average ages of 33.3 and 27.3 kyrs that are similar to the age of T2. This suggest that these</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006ApJ...640.1163G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006ApJ...640.1163G"><span id="translatedtitle">The Irradiation Origin of Beryllium Radioisotopes and Other Short-lived Radionuclides</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gounelle, Matthieu; Shu, Frank H.; Shang, Hsien; Glassgold, A. E.; Rehm, K. E.; Lee, Typhoon</p> <p>2006-04-01</p> <p>Two explanations exist for the short-lived radionuclides (T1/2<=5 Myr) present in the solar system when the calcium-aluminum-rich inclusions (CAIs) first formed. They originated either from the ejecta of a supernova or by the in situ irradiation of nebular dust by energetic particles. With a half-life of only 53 days, 7Be is then the key discriminant, since it can be made only by irradiation. Using the same irradiation model developed earlier by our group, we calculate the yield of 7Be. Within model uncertainties associated mainly with nuclear cross sections, we obtain agreement with the experimental value. Moreover, if 7Be and 10Be have the same origin, the irradiation time must be short (a few to tens of years), and the proton flux must be of order F~2×1010 cm-2 s-1. The X-wind model provides a natural astrophysical setting that gives the requisite conditions. In the same irradiation environment, <span class="hlt">26</span><span class="hlt">Al</span>, <span class="hlt">36</span><span class="hlt">Cl</span>, and 53Mn are also generated at the measured levels within model uncertainties, provided that irradiation occurs under conditions reminiscent of solar impulsive events (steep energy spectra and high 3He abundance). The decoupling of the <span class="hlt">26</span><span class="hlt">Al</span> and 10Be observed in some rare CAIs receives a quantitative explanation when rare gradual events (shallow energy spectra and low 3He abundance) are considered. The yields of <span class="hlt">41</span><span class="hlt">Ca</span> are compatible with an initial solar system value inferred from the measured initial <span class="hlt">41</span><span class="hlt">Ca</span>/40Ca ratio and an estimate of the thermal metamorphism time (from Young et al.), alleviating the need for two-layer proto-CAIs. Finally, we show that the presence of supernova-produced 60Fe in the solar accretion disk does not necessarily mean that other short-lived radionuclides have a stellar origin.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JApA...35..121S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JApA...35..121S"><span id="translatedtitle">Evolution of the Galaxy and the Birth of the Solar System: The Short-Lived Nuclides Connection</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sahijpal, S.</p> <p>2014-06-01</p> <p>An attempt is made, probably for the first time, to understand the origin of the solar system in context with the evolution of the galaxy as a natural consequence of the birth of several generations of stellar clusters. The galaxy is numerically simulated to deduce the inventories of the short-lived nuclides, <span class="hlt">26</span><span class="hlt">Al</span>, <span class="hlt">36</span><span class="hlt">Cl</span>, <span class="hlt">41</span><span class="hlt">Ca</span>, 53Mn and 60Fe, from the stellar nucleosynthetic contributions of the various stellar clusters using an N-body simulation with updated prescriptions of the astrophysical processes. The galaxy is evolved by considering the discreteness associated with the stellar clusters and individual stars. We estimate the steady state abundance of the radionuclides around 4.56 billion years ago at the time of formation of the solar system. Further, we also estimate the present <span class="hlt">26</span><span class="hlt">Al</span>/27Al and 60Fe/56Fe of the interstellar medium that match within a factor of two with the observed estimates. In contrary to the conventional Galactic Chemical Evolution (GCE) model, the present adopted numerical approach provides a natural framework to understand the astrophysical environment related with the origin of the solar system. We deduce the nature of the two stellar clusters; the one that formed and evolved prior to the solar system formation, and the other within which the solar system that was probably formed. The former could have contributed to the short-lived nuclides 129I and 53Mn, whereas, the supernova associated with the most massive star in the latter contributed <span class="hlt">26</span><span class="hlt">Al</span> and 60Fe to the solar system. The analysis was performed with the revised solar metallicity of 0.014.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006A%26A...453..653A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006A%26A...453..653A"><span id="translatedtitle">The production of short-lived radionuclides by new non-rotating and rotating Wolf-Rayet model stars</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Arnould, M.; Goriely, S.; Meynet, G.</p> <p>2006-07-01</p> <p>Context.It has been speculated that WR winds may have contaminated the forming solar system, in particular with short-lived radionuclides (half-lives in the approximate 10^5{-}108 y range) that are responsible for a class of isotopic anomalies found in some meteoritic materials.Aims.We revisit the capability of the WR winds to eject these radionuclides using new models of single non-exploding WR stars with metallicity Z = 0.02.Methods. The earlier predictions for non-rotating WR stars are updated, and models for rotating such stars are used for the first time in this context.Results. We find that (1) rotation has no significant influence on the short-lived radionuclide production by neutron capture during the core He-burning phase, and (2) {}<span class="hlt">26</span>{<span class="hlt">Al</span>},{}<span class="hlt">36</span>{<span class="hlt">Cl</span>}, {}<span class="hlt">41</span>{<span class="hlt">Ca</span>}, and {}107{Pd} can be wind-ejected by a variety of WR stars at relative levels that are compatible with the meteoritic analyses for a period of free decay of around 105 y between production and incorporation into the forming solar system solid bodies.Conclusions.We confirm the previously published conclusions that the winds of WR stars have a radionuclide composition that can meet the necessary condition for them to be a possible contaminating agent of the forming solar system. Still, it remains to be demonstrated from detailed models that this is a sufficient condition for these winds to have provided a level of pollution that is compatible with the observations.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_11 --> <div id="page_12" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="221"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18470926','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18470926"><span id="translatedtitle">Accelerator mass spectrometry.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hellborg, Ragnar; Skog, Göran</p> <p>2008-01-01</p> <p>In this overview the technique of accelerator mass spectrometry (AMS) and its use are described. AMS is a highly sensitive method of counting atoms. It is used to detect very low concentrations of natural isotopic abundances (typically in the range between 10(-12) and 10(-16)) of both radionuclides and stable nuclides. The main advantages of AMS compared to conventional radiometric methods are the use of smaller samples (mg and even sub-mg size) and shorter measuring times (less than 1 hr). The equipment used for AMS is almost exclusively based on the electrostatic tandem accelerator, although some of the newest systems are based on a slightly different principle. Dedicated accelerators as well as older "nuclear physics machines" can be found in the 80 or so AMS laboratories in existence today. The most widely used isotope studied with AMS is 14C. Besides radiocarbon dating this isotope is used in climate studies, biomedicine applications and many other fields. More than 100,000 14C samples are measured per year. Other isotopes studied include 10Be, <span class="hlt">26</span><span class="hlt">Al</span>, <span class="hlt">36</span><span class="hlt">Cl</span>, <span class="hlt">41</span><span class="hlt">Ca</span>, 59Ni, 129I, U, and Pu. Although these measurements are important, the number of samples of these other isotopes measured each year is estimated to be less than 10% of the number of 14C samples.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19980211596','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19980211596"><span id="translatedtitle"><span class="hlt">26</span><span class="hlt">Al</span> Emission Structure Along the Galactic Plane</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Purcell, William R.</p> <p>1996-01-01</p> <p>During the grant period (February 1995 - February 1996), the NU team members worked to analyze the available data. Results of this analysis were presented at the 24(th) international Cosmic Ray Conference held in Rome, Italy, August 28 - September 8, 1995, and at the 1996 meeting of the AAS/High Energy Astrophysics Division held in San Diego, California, April 30 - May 3, 1996. The results were also published in the conference proceedings of the Cosmic Ray Conference. As a result of this work, subsequent proposals have been submitted to continue this effort and to develop enhanced capabilities for OSSE observations of high energy emission.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUSM.A11C..09E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUSM.A11C..09E"><span id="translatedtitle">A New Technology for Elimination of Isobaric Interferences in Ultra-Sensitive Isotope Measurements</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Eliades, J.; Zhao, X.; Litherland, T.; Kieser, L.; Cousins, L.; Ye, J.</p> <p>2009-05-01</p> <p>Accelerator Mass Spectrometry (AMS) is a technique used for ultra-sensitive abundance ratio measurements. Applications in the earth sciences typically involve the measurement of 10Be, 14C, <span class="hlt">26</span><span class="hlt">Al</span>, <span class="hlt">36</span><span class="hlt">Cl</span>, <span class="hlt">41</span><span class="hlt">Ca</span> and 129I, for example in exposure dating and ground water studies, sometimes yielding ratios of unstable to stable isotope at 10-15 or less. AMS is most effective when the stable atomic isobar does not form a stable negative ion. When this is not the case larger accelerators have been required. Here we report preliminary tests of a prototype radio-frequency quadrupole collision cell system for the removal of isobaric interferences for Accelerator Mass Spectrometry (AMS) and for studies of anion-gas interactions at low energy. A fully developed ISA could allow smaller AMS systems to handle a wider range of samples. This system, known as an Isobar Separator for Anions (ISA), decelerates a mass-analyzed beam of anions from an energy typically generated by an AMS ion source (˜20 keV) down to < 10 eV. Radiofrequency quardrupoles and electrostatic lenses then guide the ions through the collision cell where ion-gas reactions attenuate most of the unwanted isobars and ion-gas elastic collisions reduce the ion energy and energy spread of the ion beam (cool the ions). The anions are then reaccelerated to their original energy for injection into the rest of the AMS system. With the ISA installed on a full 3MV AMS system, attenuations of 32S-, 12C3-, and 39K- by six, seven, and > ten orders of magnitude respectively have been achieved using NO2 gas in the collision cell. Transmission of a non-reactive anion is approximately 10-20% through the ISA. Further measurements of four <span class="hlt">36</span><span class="hlt">Cl</span> standards (4 x 10-13 < <span class="hlt">36</span><span class="hlt">Cl</span>/Cl < 4 x 10-11) and an estimate of the attenuation of the interfering isobars 36S-and 12C3-is also described.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19860022897','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19860022897"><span id="translatedtitle">Neutron capture production rates of cosmogenic 60Co, 59Ni and <span class="hlt">36</span><span class="hlt">Cl</span> in stony meteorites</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Spergel, M. S.; Reedy, R. C.; Lazareth, O. W.; Levy, P. W.</p> <p>1986-01-01</p> <p>Results for neutron flux calculations in stony meteoroids (of various radii and compositions) and production rates for Cl-36, Ni-59, and Co-60 are reported. The Ni-59/Co-60 ratio is nearly constant with depth in most meteorites: this effect is consistent with the neutron flux and capture cross section properties. The shape of the neutron flux energy spectrum, varies little with depth in a meteorite. The size of the parent meteorite can be determined from one of its fragments, using the Ni-59/Co-60 ratios, if the parent meteorite was less than 75 g/cm(2) in radius. If the parent meteorite was larger, a lower limit on the size of the parent meteorite can be determined from a fragment. In C3 chondrites this is not possible. In stony meteorites with R less than 50 g/cm(2) the calculated Co-60 production rates (mass less than 4 kg), are below 1 atom/min g-Co. The highest Co-60 production rates occur in stony meteorites with radius about 250 g/cm(2) (1.4 m across). In meteorites with radii greater than 400 g/cm(2), the maximum Co-60 production rate occurs at a depth of about 175 g/cm(2) in L-chondrite, 125 g/cm(2) in C3 chrondrite, and 190 g/cm(2) in aubrites.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014NIMPB.329...22P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014NIMPB.329...22P"><span id="translatedtitle">Interlaboratory study of the ion source memory effect in <span class="hlt">36</span><span class="hlt">Cl</span> accelerator mass spectrometry</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pavetich, Stefan; Akhmadaliev, Shavkat; Arnold, Maurice; Aumaître, Georges; Bourlès, Didier; Buchriegler, Josef; Golser, Robin; Keddadouche, Karim; Martschini, Martin; Merchel, Silke; Rugel, Georg; Steier, Peter</p> <p>2014-06-01</p> <p>Understanding and minimization of contaminations in the ion source due to cross-contamination and long-term memory effect is one of the key issues for accurate accelerator mass spectrometry (AMS) measurements of volatile elements. The focus of this work is on the investigation of the long-term memory effect for the volatile element chlorine, and the minimization of this effect in the ion source of the Dresden accelerator mass spectrometry facility (DREAMS). For this purpose, one of the two original HVE ion sources at the DREAMS facility was modified, allowing the use of larger sample holders having individual target apertures. Additionally, a more open geometry was used to improve the vacuum level. To evaluate this improvement in comparison to other up-to-date ion sources, an interlaboratory comparison had been initiated. The long-term memory effect of the four Cs sputter ion sources at DREAMS (two sources: original and modified), ASTER (Accélérateur pour les Sciences de la Terre, Environnement, Risques) and VERA (Vienna Environmental Research Accelerator) had been investigated by measuring samples of natural 35Cl/37Cl-ratio and samples highly-enriched in 35Cl (35Cl/37Cl ∼ 999). Besides investigating and comparing the individual levels of long-term memory, recovery time constants could be calculated. The tests show that all four sources suffer from long-term memory, but the modified DREAMS ion source showed the lowest level of contamination. The recovery times of the four ion sources were widely spread between 61 and 1390 s, where the modified DREAMS ion source with values between 156 and 262 s showed the fastest recovery in 80% of the measurements.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/publication/?seqNo115=209973','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=209973"><span id="translatedtitle">Total radioactive residues and residues of [<span class="hlt">36</span><span class="hlt">Cl</span>]chlorate in market size broilers.</span></a></p> <p><a target="_blank" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p></p> <p></p> <p>The oral administration of chlorate salts reduces the numbers of Gram-negative pathogens in gastrointestinal tracts of live food animals. Although the efficacy of chlorate salts has been demonstrated repeatedly, the technology cannot be introduced into commercial settings without first demonstrating...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009GeCoA..73.4963K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009GeCoA..73.4963K"><span id="translatedtitle">Origin and chronology of chondritic components: A review</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Krot, A. N.; Amelin, Y.; Bland, P.; Ciesla, F. J.; Connelly, J.; Davis, A. M.; Huss, G. R.; Hutcheon, I. D.; Makide, K.; Nagashima, K.; Nyquist, L. E.; Russell, S. S.; Scott, E. R. D.; Thrane, K.; Yurimoto, H.; Yin, Q.-Z.</p> <p>2009-09-01</p> <p>Mineralogical observations, chemical and oxygen-isotope compositions, absolute 207Pb- 206Pb ages and short-lived isotope systematics ( 7Be- 7Li, 10Be- 10B, <span class="hlt">26</span><span class="hlt">Al</span>- 26Mg, <span class="hlt">36</span><span class="hlt">Cl</span>- 36S, <span class="hlt">41</span><span class="hlt">Ca</span>- 41K, 53Mn- 53Cr, 60Fe- 60Ni, 182Hf- 182W) of refractory inclusions [Ca,Al-rich inclusions (CAIs) and amoeboid olivine aggregates (AOAs)], chondrules and matrices from primitive (unmetamorphosed) chondrites are reviewed in an attempt to test (i) the x-wind model vs. the shock-wave model of the origin of chondritic components and (ii) irradiation vs. stellar origin of short-lived radionuclides. The data reviewed are consistent with an external, stellar origin for most short-lived radionuclides ( 7Be, 10Be, and <span class="hlt">36</span><span class="hlt">Cl</span> are important exceptions) and a shock-wave model for chondrule formation, and provide a sound basis for early Solar System chronology. They are inconsistent with the x-wind model for the origin of chondritic components and a local, irradiation origin of <span class="hlt">26</span><span class="hlt">Al</span>, <span class="hlt">41</span><span class="hlt">Ca</span>, and 53Mn. 10Be is heterogeneously distributed among CAIs, indicating its formation by local irradiation and precluding its use for the early solar system chronology. <span class="hlt">41</span><span class="hlt">Ca</span>- 41K, and 60Fe- 60Ni systematics are important for understanding the astrophysical setting of Solar System formation and origin of short-lived radionuclides, but so far have limited implications for the chronology of chondritic components. The chronological significance of oxygen-isotope compositions of chondritic components is limited. The following general picture of formation of chondritic components is inferred. CAIs and AOAs were the first solids formed in the solar nebula ˜4567-4568 Myr ago, possibly within a period of <0.1 Myr, when the Sun was an infalling (class 0) and evolved (class I) protostar. They formed during multiple transient heating events in nebular region(s) with high ambient temperature (at or above condensation temperature of forsterite), either throughout the inner protoplanetary disk (1-4 AU) or in a localized region</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.V31G..09C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.V31G..09C"><span id="translatedtitle">The Gas-Filled-Magnet at PRIME Lab: Increased Sensitivity of Cosmogenic Nuclide Measurements</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Caffee, M. W.; Granger, D. E.; Woodruff, T. E.</p> <p>2015-12-01</p> <p>Abstract: Using accelerator mass spectrometry (AMS), radionuclides produced either by cosmic-ray interactions or by nucleogenic means can be measured. Typical isotopic abundance ratios range from 1 x 10-10 to 1 x 10-15. The routinely measured radionuclides are 10Be, 14C, <span class="hlt">26</span><span class="hlt">Al</span>, <span class="hlt">36</span><span class="hlt">Cl</span>, and 129I. Be-10, <span class="hlt">26</span><span class="hlt">Al</span>, and <span class="hlt">36</span><span class="hlt">Cl</span> have isobaric interferences that cannot be eliminated mass through mass analysis, but dE/dx techniques suppresses these isobars enough to allow successful measurements. There are compromises, the isobar for <span class="hlt">26</span><span class="hlt">Al</span>, 26Mg, precludes successful measurement of <span class="hlt">26</span><span class="hlt">Al</span> if AlO- is injected into the accelerator. Mg- doesn't form a stable negative ion so a <span class="hlt">26</span><span class="hlt">Al</span> measurement requires injection of <span class="hlt">26</span><span class="hlt">Al</span>-. But the Al- ion is formed inefficiently; secondary ion currents using Al- are ~ 10 times less than an AlO- secondary ion beam. Precision scales with count rate so precise measurement of the <span class="hlt">26</span><span class="hlt">Al</span>/Al for all but higher ratio samples is difficult. It has long been recognized that a gas-filled-magnet (GFM) could potentially improve the measurement of those radionuclides with intractable isobar interferences. A GFM works on the principle that each element of an isobar pair, e.g. 26Mg and <span class="hlt">26</span><span class="hlt">Al</span>, has a different average charge state as it traverses a gas (3-4 Torr of N2) contained within the vacuum jacket of a magnet. The magnet steers each species with its own momentum-to-charge ratio on its own distinct radius of curvature. The magnet can be tuned to allow the isotope of interest into a dE/dx detector; most of the isobar doesn't make it into the detector. Using the PRIME Lab GFM we are now able to routinely run <span class="hlt">26</span><span class="hlt">Al</span> with a precision that is comparable to that obtained with 10Be. We are also using the GFM for routine measurements of 10Be and <span class="hlt">36</span><span class="hlt">Cl</span>. Although the improvement for these nuclides is not as pronounced as it is for <span class="hlt">26</span><span class="hlt">Al</span>, the GFM has improved the detection sensitivity for both. Our 10Be background is now ~ 5 x 10-16 and for <span class="hlt">36</span><span class="hlt">Cl</span> we can now run the source more</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1998IAUS..191P.121G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1998IAUS..191P.121G"><span id="translatedtitle">Short-lived Isotopes from a Close-by AGB Star Triggering the Protosolar Nebula</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gallino, R.; Busso, M.; Wasserburg, G. J.; Straniero, O.</p> <p></p> <p>The presence of short-lived isotopes in the early solar system, in particular <span class="hlt">26</span><span class="hlt">Al</span>, <span class="hlt">41</span><span class="hlt">Ca</span>, 60Fe, and 107Pd, point to a close-by and fresh nucleosynthesis source, possibly triggering the collapse of the protosolar nebula. We present the results of nucleosynthesis calculations based on an AGB polluting hypothesis. A general concordance of the predicted yields of the above radioactivities relative to <span class="hlt">26</span><span class="hlt">Al</span> can be obtained in the case of an intermediate mass AGB star with hot bottom burning in the envelope (thus producing <span class="hlt">26</span><span class="hlt">Al</span>), and mixing through a series of third dredge-up episodes a fraction of the C-rich and s-processed material from the He intershell with the extended envelope. Polution of the protosolar nebula with freshly synthesized material may derive from the efficient winds of the AGB star. In AGB stars, the s-process nucleosynthesis occurs both during the maximum phase of every thermal runaway, driven by the partial activation of the 22Ne(alpha,n)25Mg reaction, and in the interpulse phase, where the 13C nuclei are fully consumed in radiative conditions by the activation of the 13C(alpha,n)16O reaction. We have used different prescriptions for the amount of the 13C nuclei present in the intershell. A minimum amount of 13C is naturally expected in the ashes of H-shell burning. Possible formation of an extra "13C-pocket" derives from the injection of a small amount of protons from the envelope into the 12C-rich intershell during any third dredge-up episode, when the H-shell is inactivated. Prediction for other short-lived, <span class="hlt">36</span><span class="hlt">Cl</span>, 135Cs, and 205Pb, are given. General consequences for the pollution of the protosolar nebula with newly synthesized stable isotopes from the AGB winds are outlined. The origin of other detected short-lived nuclei, in particular 53Mn, 129I, and 182Hf, which cannot come from an AGB source, is analysed. The alternative trigger hypothesis by a close-by Supernova is discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/803429','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/803429"><span id="translatedtitle">Exposure Histories of Lunar Meteorites Northwest Africa 032 and DHOFAR 081</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Nishiizumi, K.; Caffee, M.</p> <p>2001-04-01</p> <p>Recent additions to the list of lunar meteorites include Northwest Africa (NWA) 032 and Dhofar 081. NWA 032 is an unbrecciated basalt, found in Morocco; Dhofar 081 is a fragmented feldspathic breccia, found in Oman. Our goal is the determination of the cosmic ray exposure history of these objects. Most lunar meteorites have complex cosmic ray exposure histories, having been exposed both at some depth on the lunar surface (2{pi} irradiation) before their ejection and as small bodies in space (4{pi} irradiation) during transport from the Moon to the Earth. These exposures were then followed by residence on the Earth's surface, the terrestrial residence time. Unraveling the complex history of these objects requires the measurement of at least four cosmogenic nuclides. The specific goals of these measurements are to constrain the depth of the sample at the time of ejection from the Moon, the transit time from the time of ejection to the time of capture by the Earth, and the residence time on the Earth's surface. These exposure durations in conjunction with the sample depth on the Moon can then be used to model impact and ejection mechanisms. To investigate the complex exposure histories of lunar meteorites, we measured cosmogenic nuclides, {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> (half-life = 3.01 x 10{sup 5} yr), {sup <span class="hlt">26</span>}<span class="hlt">Al</span> (7.05 x 10{sup 5} yr), and {sup 10}Be (1.5 x 10{sup 6} yr) in NWA 032 and Dhofar 081. The measurements of {sup <span class="hlt">41</span>}<span class="hlt">Ca</span> (1.04 x 10{sup 5} yr) are in progress.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006M%26PSA..41..217A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006M%26PSA..41..217A"><span id="translatedtitle">Shisr 043 (IIIAB medium octahedrite): The first iron meteorite from the Oman desert</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Al-Kathiri, A.; Hofmann, B. A.; Gnos, E.; Eugster, O.; Welten, K. C.; Krähenbühl, U.</p> <p>2006-08-01</p> <p>The iron meteorite Shi?r 043 is a single mass of 8267 g found in the south Oman desert 42 km NE of the Shi?r village. It is the first iron identified among the >1400 individual meteorites reported from Oman. The meteorite is a slightly elongated mass showing only minor rusting, a partially smooth and partially rough surface with octahedral cleavage, and a partially preserved metallic fusion crust typically 0.75 mm thick. The undeformed Widmanstätten pattern with a mean kamacite bandwidth of 1.0 +/- 0.1 mm (n = 97) indicates structural classification as a medium octahedrite. From the bulk composition, Ni = 8.06 wt%, Ga = 18.8 ppm, Ge = 37.25 ppm, and Ir = 3.92 ppm, the meteorite is classified as IIIAB, the most common group of iron meteorites. The cosmic-ray exposure (CRE) age based on 3He, 21Ne, 38Ar concentrations and 10Be-21Ne, <span class="hlt">26</span><span class="hlt">Al</span>-21Ne, and <span class="hlt">36</span><span class="hlt">Cl</span>-36Ar ratios is 290 +/- 20 Ma. This age falls within the range observed for type IIIAB iron meteorites, but does not coincide with the main cluster. The cosmogenic noble gas and radionuclide data indicate that Shi?r 043 had a relatively small pre-atmospheric mass. The low degree of weathering is consistent with a young terrestrial age of <10,000 years based on the saturated <span class="hlt">41</span><span class="hlt">Ca</span> concentration. Shi?r 043 is not paired with any of the other eight known iron meteorites from the Arabian Peninsula.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006M%26PS...41.1081W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006M%26PS...41.1081W"><span id="translatedtitle">Terrestrial ages, pairing, and concentration mechanism of Antarctic chondrites from Frontier Mountain, Northern Victoria Land</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Welten, K. C.; Nishiizumi, K.; Caffee, M. W.; Hillegonds, D. J.; Johnson, J. A.; Jull, A. J. T.; Wieler, R.; Folco, L.</p> <p></p> <p>We report concentrations of cosmogenic 10Be, <span class="hlt">26</span><span class="hlt">Al</span>, <span class="hlt">36</span><span class="hlt">Cl</span>, and <span class="hlt">41</span><span class="hlt">Ca</span> in the metal phase of 26 ordinary chondrites from Frontier Mountain (FRO), Antarctica, as well as cosmogenic 14C in eight and noble gases in four bulk samples. Thirteen out of 14 selected H chondrites belong to two previously identified pairing groups, FRO 90001 and FRO 90174, with terrestrial ages of ˜40 and ˜100 kyr, respectively. The FRO 90174 shower is a heterogeneous H3-6 chondrite breccia that probably includes more than 300 individual fragments, explaining the high H/L chondrite ratio (3.8) at Frontier Mountain. The geographic distribution of 19 fragments of this shower constrains ice fluctuations over the past 50-100 kyr to less than ˜40 m, supporting the stability of the meteorite trap over the last glacial cycle. The second H-chondrite pairing group, FRO 90001, is much smaller and its geographic distribution is mainly controlled by wind-transport. Most L-chondrites are younger than 50 kyr, except for the FRO 93009/01172 pair, which has a terrestrial age of ˜500 kyr. These two old L chondrites represent the only surviving members of a large shower with a similar preatmospheric radius (˜80 cm) as the FRO 90174 shower. The find locations of these two paired L-chondrite fragments on opposite sides of Frontier Mountain confirm the general glaciological model in which the two ice flows passing both ends of the mountain are derived from the same source area on the plateau. The 50 FRO meteorites analyzed so far represent 21 different falls. The terrestrial ages range from 6 kyr to 500 kyr, supporting the earlier proposed concentration mechanism.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/5860136','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/5860136"><span id="translatedtitle">The use of AMS to the biomedical sciences</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Vogel, J.S.</p> <p>1991-04-01</p> <p>The Center for Accelerator Mass Spectroscopy (AMS) began making AMS measurements in 1989. Biomedical experiments were originally limited by sample preparation techniques, but we expect the number of biomedical samples to increase five-fold. While many of the detailed techniques for making biomedical measurements resemble those used in other fields, biological tracer experiments differ substantially from the observational approaches of earth science investigators. The role of xenobiotius in initiating mutations in cells is of particular interest. One measure of the damage caused to the genetic material is obtained by counting the number of adducts formed by a chemical agent at a given dose. AMS allows direct measurement of the number of adducts through stoichiometric quantification of the {sup 14}C label attached to the DNA after exposure to a labelled carcinogen. Other isotopes of interest include tritium, {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>, {sup 79}SE, {sup <span class="hlt">41</span>}<span class="hlt">Ca</span>, {sup <span class="hlt">26</span>}<span class="hlt">Al</span> and {sup 129}I. Our experiments with low dose environmental carcinogens reflect the protocols which will become a common part of biomedical AMS. In biomedical experiments, the researcher defines the carbon to be analyzed through dissection and/or chemical purification; thus the sample is merely'' combusted and graphitized at the AMS facility. However, since biomedical samples can have a {sup 14}C range of five orders of magnitude, preparation of graphite required construction of a special manifold to prevent cross-contamination. Additionally, a strain of {sup 14}C-depleted C57BL/6 mice is being developed to further reduce background in biomedical experiments. AMS has a bright and diverse future in radioisotope tracing. Such work requires a dedicated amalgamation of AMS scientists and biomedical researchers who will redesign experimental protocols to maximize the AMS technique and minimize the danger of catastrophic contamination. 18 refs., 4 figs., 1 tab.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2000SSRv...92..133M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000SSRv...92..133M"><span id="translatedtitle">Short-Lived Radioactivities and the Birth of the sun</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Meyer, Bradley S.; Clayton, Donald D.</p> <p>2000-04-01</p> <p>Now extinct short-lived radioactive isotopes were apparently extant in the early solar system. Their abundances can be inferred from isotopic effects in their daughter nuclei in primitive meteorites, and the deviation of these abundances from expectations from continuous galactic nucleosynthesis yields important information on the last nucleosynthetic events that contributed new nuclei to the solar system and on the general circumstances of the Sun's birth. In this paper we present a rudimentary model that attempts to reconcile the abundances of ten short-lived radioactivities in the early solar system. In broad outlines, the picture requires 1) that Type Ia supernovae maintained a steady ISM supply of 53Mn and 146Sm, 2) that the r-process events that slowly admixed new 107Pd, 129I, 182Hf, and 244Pu nuclei to the solar system occurred over an interval of several hundred million years prior to solar system formation, and 3) that a massive star, by injecting only material outside its helium-exhausted core into the proto-solar nebula, contributed <span class="hlt">26</span><span class="hlt">Al</span>, <span class="hlt">36</span><span class="hlt">Cl</span>, <span class="hlt">41</span><span class="hlt">Ca</span>, 60Fe, and 182Hf no more than one million years prior to the Sun's birth. In this picture, the live 182Hf present in the early solar system was not due to r-process production but rather to a fast s-process in helium or carbon burning shell in the massive star. We conclude with a possible chemical-memory explanation for the putative 53Cr/52Cr gradient in the solar system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/12481135','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12481135"><span id="translatedtitle">Short-lived nuclides in hibonite grains from Murchison: evidence for solar system evolution.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Marhas, K K; Goswami, J N; Davis, A M</p> <p>2002-12-13</p> <p>Records of now-extinct short-lived nuclides in meteorites provide information about the formation and evolution of the solar system. We have found excess 10B that we attribute to the decay of short-lived 10Be (half-life 1.5 million years) in hibonite grains from the Murchison meteorite. The grains show no evidence of decay of two other short-lived nuclides-<span class="hlt">26</span><span class="hlt">Al</span> (half-life 700,000 years) and <span class="hlt">41</span><span class="hlt">Ca</span> (half-life 100,000 years)-that may be present in early solar system solids. One plausible source of the observed 10Be is energetic particle irradiation of material in the solar nebula. An effective irradiation dose of approximately 2 x 10(18) protons per square centimeter with a kinetic energy of >/=10 megaelectronvolts per atomic mass unit can explain our measurements. The presence of 10Be, coupled with the absence of <span class="hlt">41</span><span class="hlt">Ca</span> and <span class="hlt">26</span><span class="hlt">Al</span>, may rule out energetic particle irradiation as the primary source of <span class="hlt">41</span><span class="hlt">Ca</span> and <span class="hlt">26</span><span class="hlt">Al</span> present in some early solar system solids and strengthens the case of a stellar source for <span class="hlt">41</span><span class="hlt">Ca</span> and <span class="hlt">26</span><span class="hlt">Al</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMEP53B1025S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMEP53B1025S"><span id="translatedtitle">Exploring the cliff retreat response to base level change using SFM photogrammetry and cosmogenic <span class="hlt">36</span><span class="hlt">Cl</span>, Coal Cliffs, Utah, USA</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sheehan, C.; Ward, D.</p> <p>2015-12-01</p> <p>The retreat of cliffbands is an important erosional process within the relatively undeformed sedimentary layers of the Colorado Plateau. Many iconic cliff landforms, including those of Monument Valley and Grand Canyon, are maintained by the interaction of these different rock types. A several kilometer thickness of incised sandstone and shale formations allow this region to act as a natural laboratory for studying the effects of variable lithologies on landscape evolution. Cliffband morphology and retreat on the plateau are controlled by several factors that may vary over time and space, including lithology, rate and distribution of rockfall debris, bedrock structure, baselevel, and climate. The relative importance of each factor in setting rates of cliff retreat are not entirely clear. Because regional headwaters are commonly sourced at cliff bases, these landforms are often the final and slowest areas to respond to baselevel changes, allowing rockfall and other local stochastic processes to overwhelm the erosional response to a baselevel forcing. The roles of these processes are difficult to assess because very few measurements of retreat rates over geomorphic timescales (103-106 years) have been produced, and thus changes in cliffband position through time have only been constrained by inferences made from the regional erosional history. Here, we control for climate and rock type by focusing on a continuous, 40-kilometer section of the lithologically consistent Coal Cliffs in Emery County, Utah. This area presents several natural experiments illustrating cliffband response to different forcings, including relict surfaces reflecting a baselevel change, drainage divides across which the adjustment to base level change may be asynchronous, a zone wherein the caprock layer has been removed by backscarp erosion, and a generally continuous gradient in cliff height from 50 to >200 meters along the cliffline. We employ terrestrial Cl36 exposure dating on terraces, talus flatirons, and perched boulders to constrain the rate of cliffband movement over the most recent period of retreat. Field mapping, relative weathering measurements, and high-resolution DEMs created from structure-from-motion (SFM) photogrammetry are used to evaluate the morphological response in each case.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1993Metic..28R.429S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1993Metic..28R.429S"><span id="translatedtitle">Cross Sections for the Production of Cosmogenic Nuclides with Protons up to 400 MeV for the Interpretation of Cosmic-Ray-produced Nuclides</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schiekel, Th.; Rosel, R.; Herpers, U.; Bodemann, R.; Leya, I.; Gloris, M.; Michel, R.; Dittrich, B.; Kubik, P.; Suter, M.</p> <p>1993-07-01</p> <p>Integral excitation functions of the cosmogenic nuclides are the basic requirement for the interpretation of interactions between cosmic ray particles and extraterrestrial and terrestrial matter. Together with the knowledge of primary and secondary particle fields inside an irradiated body, model calculations can be developed to interpret abundances of cosmogenic nuclides in dependencies of the irradiation history of the irradiated body and of the cosmic particle ray itself. The quality of those model calculations depends on the quality of the available cross-section database, which is neither comprehensive nor reliable for the most important nuclides like the long-lived radionuclides (i.e., 10Be, <span class="hlt">26</span><span class="hlt">Al</span>, <span class="hlt">36</span><span class="hlt">Cl</span>, <span class="hlt">41</span><span class="hlt">Ca</span>) and the stable rare gas isotopes. For a systematic investigation in this field of science we carried out several irradiation experiments with protons in the energy region between 45 MeV and 400 MeV at the Paul Scherrer Institut (Villigen, Switzerland) and the Laboratoire Nationale Saturne (Saclay, France) using the stacked foil technique. We included 21 different target elements with Z between 6 and 79 (C, N as Si3N4, O as SiO2, Mg, Al, Si, Ca as CaC2H2O4, Ti, V, Mn as Mn/Ni alloy, Fe, Co, Ni, Cu, Sr as SrF2, Y, Zr, Nb, Rh, Ba as Ba containing glass and Au) in our experiments. The proton fluxes were monitored via the reaction 27Al(p,3p3n)22Na using the evaluated data of [1]. Residual nuclides were measured by X-, gamma-, and after a chemical separation by accelerator mass spectrometry. In order to check the quality of our experimental procedures we included some target elements in our new experiments for which consistent excitation functions have already been determined [2,3,4]. Our new data show excellent agreement with the earlier measurements. We measured cross sections for more than 120 different reactions. Here we report on the results for target elements with Z up to 28. The exsisting database of experimental excitation functions for the production</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/126698','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/126698"><span id="translatedtitle">Biomedical applications of AMS at ANU</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Fifield, L.K.; Cresswell, R.G.; Day, J.P.; King, S.J.</p> <p>1995-12-01</p> <p>Studies utilising {sup <span class="hlt">26</span>}<span class="hlt">Al</span> have constituted the bulk of the biomedical AMS program at the ANU`s 14UD accelerator. Projects underway or completed include: the dependence on chemical form of aluminum uptake from the gut; the partitioning of Al among the various components of cells and blood; and uptake of Al by Alzheimer`s patients. In addition, capabilities for measuring {sup 32}Si, {sup <span class="hlt">41</span>}<span class="hlt">Ca</span> and plutonium in a biomedical context have been established during the past year. Results of the {sup <span class="hlt">26</span>}<span class="hlt">Al</span> studies and an outline of the methodology for the other isotopes will be presented and discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/7629443','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/7629443"><span id="translatedtitle">Neutron spectrum and yield of the Hiroshima A-bomb deduced from radionuclide measurements at one location.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rühm, W; Kato, K; Korschinek, G; Morinaga, H; Nolte, E</p> <p>1995-07-01</p> <p>In this paper measurements of the radionuclides of <span class="hlt">36</span><span class="hlt">Cl</span>, <span class="hlt">41</span><span class="hlt">Ca</span>, 60Co, 152Eu and 154Eu in samples from Hiroshima, which were exposed to neutrons of the A-bomb explosion, are interpreted. In order to calculate the neutron spectrum at the sample site, neutron transport calculations using Monte Carlo techniques were carried out. Activation profiles in a granite mock-up irradiated with reactor neutrons could be reproduced by this method using DS86 input parameters. The calculated neutron spectrum at the sample site for non-thermal neutrons is identical to that obtained in DS86, but contains some 50% more thermal neutrons. The influence of parameters like soil composition, source terms and air humidity on the activation of these radioisotopes is discussed. The granite-covered earth at the sample site, for example, hardens the spectrum in comparison with DS86 values. Even when using a fission spectrum pointing downward and neglecting air humidity one cannot explain our <span class="hlt">36</span><span class="hlt">Cl</span> measurements. If the effective thermal neutron fluences, that have a similar ratio of resonance integral to thermal neutron capture cross sections obtained from <span class="hlt">36</span><span class="hlt">Cl</span>, <span class="hlt">41</span><span class="hlt">Ca</span> and 152Eu, are averaged, a bomb yield of about 16 kt is deduced in agreement with a bomb yield of (15 +/- 3) kt estimated in DS86.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014ApJ...796..124T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014ApJ...796..124T"><span id="translatedtitle">Light-element Nucleosynthesis in a Molecular Cloud Interacting with a Supernova Remnant and the Origin of Beryllium-10 in the Protosolar Nebula</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tatischeff, Vincent; Duprat, Jean; de Séréville, Nicolas</p> <p>2014-12-01</p> <p>-atom cm-3, and eventually interacted with the presolar molecular cloud only during the radiative stage. This model naturally provides an explanation for the injection of other short-lived radionuclides of stellar origin into the cold presolar molecular cloud (<span class="hlt">26</span><span class="hlt">Al</span>, <span class="hlt">41</span><span class="hlt">Ca</span>, and <span class="hlt">36</span><span class="hlt">Cl</span>) and is in agreement with the solar system originating from the collapse of a molecular cloud shocked by a supernova blast wave.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_12 --> <div id="page_13" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="241"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1022895','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1022895"><span id="translatedtitle">Extremely NA and CL Rich Chondrule AL3509 from the Allende Meteorite</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Wasserburg, G J; Hutcheon, I D; Aleon, J; Ramon, E C; Krot, A N; Nagashima, K; Brearley, A J</p> <p>2011-04-07</p> <p>We report on the mineralogy, petrology, chemistry, oxygen isotopes, {sup <span class="hlt">26</span>}<span class="hlt">Al</span>-{sup 26}Mg and {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>-{sup 36}S isotope systematics of the Allende chondrule Al3509 discovered and described by [1] and [2]. This spherical object ({approx}1cm {phi}) contains {approx}10% Na and 1% Cl, and nearly pure {sup 129}Xe [({sup 129}Xe/{sup 127}I) = 1.1 x 10{sup -4} (3)]. This high enrichment in halogens makes it of interest in searching for radiogenic {sup 36}S from {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> (t{sub 1/2} {approx} 0.3 Ma) decay. While there is strong evidence for the presence of {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> in sodalite and wadalite in CV CAIs [4,5], some sodalites show no evidence for excesses of {sup 36}S ({sup 36}S*). In contrast, high inferred initial {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>/{sup 35}Cl = 2 x 10{sup -5} has been found in wadalite from the Allende CAI AJEF [5]. The observed {sup 36}S excesses in sodalite are not correlated with radiogenic {sup 26}Mg, decay product of {sup <span class="hlt">26</span>}<span class="hlt">Al</span> (t{sub 1/2} {approx} 0.72 Ma) [4]. From the inferred initial {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>/{sup 35}Cl ratios and consideration of both AGB and SNe stellar sources, {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> must be the product of charged particle irradiation within the early solar system. However, neither the specific nuclear production mechanism nor the irradiation site have been identified. Both sodalite and wadalite are found as late stage alteration products of CAIs together with grossular, monticellite, Al-rich pyroxene, wollastonite, nepheline, ferroan olivine, and ferroan pyroxenes. This late-stage alteration has been found to extensively change some CAIs in Allende, but clear residues of spinel, hibonite and Wark-Lovering rims are recognizable remnants of the original CAIs. The nature of the widespread volatile alteration process as well as that of the fluid phase remain controversial.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/7132822','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/7132822"><span id="translatedtitle">Persistence and transfer of /sup <span class="hlt">36</span>/<span class="hlt">Cl</span>-DDT in the soil and biota of an old-field ecosystem: a six-year balance study</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Forsyth, D.J.; Peterle, T.J.; Bandy, L.W.</p> <p>1983-12-01</p> <p>The fate of a 1 kg/ha application of granular chlorine-36-labeled DDT made by helicopter on 10 June 1969 to a 4-ha old-field study area near Urbana, Ohio was traced and quantified in soil and biota through November 1974. Between 1970 and 1974, residues of DDT (DDTR, includes DDT plus metabolites) declined from 22.0 to 3.8 mg/kg tissue in earthworms (Lumbricus terrestris) and from 9.3 to 2.1 mg/kg in slugs (Deroceras laeve). Levels of DDTR in foliage of grasses and forbs increased from 2-3 mg/kg in 1970 to 7.6 mg/kg in 1974, but remained relatively constant at 1.6 mg/kg in roots. Amounts of residues in samples of air collected at the surface of the soil were positively correlated with amounts in soil and with air temperature. The total quantity of DDTR in the top 12 cm of soil was estimated to be 1779 g in October 1974, or 38% of the amount applied in 1969. Earthworms, which comprised the largest component of animal biomass, contained 5% of the total DDTR in the ecosystem in 1969, compared to 3% in the plants and other biota. As residues declined in earthworms and increased in plants over time, the total DDTR bound in the biota increased until it accounted for 22% of the total DDTR in the ecosystem in 1974. Losses of DDTR from the ecosystem each year were attributed primarily to volatilization from soil, because losses in runoff and emigrating insects and small mammals were negligible. 12 references, 7 figures, 6 tables.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008PhDT........25L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008PhDT........25L"><span id="translatedtitle">Short-lived radionuclides and early solar system chronology -- A hibonite perspective</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liu, Ming-Chang</p> <p></p> <p>Examination of the <span class="hlt">41</span> <span class="hlt">Ca</span>- 41 K, <span class="hlt">26</span> <span class="hlt">Al</span>- 26 Mg, 10 Be- 10 B, oxygen and titanium iso-topic systems in 26 hibonite-bearing inclusions extracted from the CM meteorite Murchison provide important constraints for origins of short-lived radionuclides, early solar system chronology, and chemical evolution. Magnesium isotopic compositions divide these hibonite grains into two distinct populations which correlate perfectly with their mineralogy and morphology, as previously discovered by Ireland (1988): Spinel-HIBonite spherules (SHIBs) bear evidence of in-situ decay of <span class="hlt">26</span> <span class="hlt">Al</span>, whereas PLAty hibonite Crystals (PLACs) and Blue AGgregates (BAGs) either lack resolvable D 26 Mg* excesses or exhibit 26 Mg deficits by up to ~4[per thousand]. High precision, multiple collector SIMS analyses show that 6 of 7 SHIBs investigated fall on a single correlation line implying <span class="hlt">26</span> <span class="hlt">Al</span>/ 27 Al = (4.4±0.2) × 10 -5 (2s) at the time of isotopic closure, consistent with the "canonical" <span class="hlt">26</span> <span class="hlt">Al</span> abundance characteristic of internal isochrons in many calcium-aluminum-rich inclusions (CAIs). One SHIB sample exhibits D 26 Mg* corresponding to a "supra-canonical" <span class="hlt">26</span> <span class="hlt">Al</span>/ 27 Al ratio 6.3 × 10 -5 which is close to the highest ratios observed in solar system materials. Eight out of 11 <span class="hlt">26</span> <span class="hlt">Al</span>-free PLAC hibonite grains record excesses of radiogenic 10 B which correlate with Be/B; the inferred initial 10 Be/ 9 Be ratio of (5.1 ± 1.4) × 10 -4 is substantially lower than the best-constrained 10 Be/ 9 Be of (8.8±0.6) × 10 -4 in a CV CAI. The data demonstrate that 10 Be cannot be used as a relative chronometer for these objects and that most of the 10 Be observed in CAIs must be produced by energetic particle irradiation of refractory dust precursors in the early solar system. The lack of <span class="hlt">26</span> <span class="hlt">Al</span> in PLAC hibonites containing Mg isotope anomalies and 10 Be indicates that significant amounts of <span class="hlt">26</span> <span class="hlt">Al</span> was not formed in the same spallogenic processes that made 10 Be in PLAC precursors. Except for few hibonite grains</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016LPICo1921.6485L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016LPICo1921.6485L"><span id="translatedtitle">High Precision Mg-Isotope Measurements of Bulk Chondrites and the Homogeneity of <span class="hlt">26</span><span class="hlt">Al</span> in the Solar Nebula</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Luu, T.-H.; Hin, R. C.; Coath, C. D.; Elliott, T.</p> <p>2016-08-01</p> <p>We have re-examined the debated issue regarding the origin of the variability in the mass-independent 26Mg compositions between bulk solar system reservoirs by making a new set of high precision Mg isotopic measurements on a suite of bulk chondrites.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=67706&keyword=mcnamara&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=80669682&CFTOKEN=57811231','EPA-EIMS'); return false;" href="http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=67706&keyword=mcnamara&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=80669682&CFTOKEN=57811231"><span id="translatedtitle">ENTRY, HALF-LIFE, AND DESFERRIOXAMINE-ACCELERATED CLEARANCE OF BRAIN ALUMINUM AFTER A SINGLE (<span class="hlt">26</span>)<span class="hlt">AL</span> EXPOSURE. (R825357)</span></a></p> <p><a target="_blank" href="http://oaspub.epa.gov/eims/query.page">EPA Science Inventory</a></p> <p></p> <p></p> <p>The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19960054326&hterms=1921&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3D1921','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19960054326&hterms=1921&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3D1921"><span id="translatedtitle">Measurement of proton production cross sections of (sup 10)Be and (sup <span class="hlt">26</span>)<span class="hlt">Al</span> from elements found in lunar rocks</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Sisterson, J. M.; Kim, K.; Englert, P. A. J.; Caffee, M.; Jull, A. J. T.; Donahue, D. J.; McHargue, L.; Castaneda, C.; Vincent, J.; Reedy, R. C.</p> <p>1996-01-01</p> <p>Cosmic rays penetrate the lunar surface and interact with the lunar rocks to produce both radionuclides and stable nuclides. Production depth profiles for long-lived radionuclides produce in lunar rocks are measured using Accelerator Mass Spectrometry (AMS). For a particular radionuclide these production depth profiles can be interpreted to give an estimate for the solar proton flux over a time period characterized by the half life of the radionuclide under study. This analysis is possible if and only if all the cross sections for the interactions of all cosmic ray particles with all elements found in lunar rocks are well known. In practice, the most important cross sections needed are the proton production cross sections, because 98% of solar cosmic rays and (similar to)87% of galactic cosmic rays are protons. The cross sections for the production of long-lived radionuclides were very difficult to measure before the development of AMS and only in recent years has significant progress been made in determining these essential cross sections. Oxygen and silicon are major constituents of lunar rocks. We have reported already C-14 production cross sections from O and Si for proton energies 25-500 MeV, and O(p,x)(sup 10)Be from 58 160 MeV[6]. Here we present new measurements for the cross sections O(p,x)Be-10,O(p,x)Be-7, Si(p,x)Be-7,Si(p,x)Al-26, and Si(p,x)Na-22 from approximately 30 - 500 MeV.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMEP53A3641M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMEP53A3641M"><span id="translatedtitle">Initial Test Determination of Cosmogenic Nuclides in Magnetite</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Matsumura, H.; Caffee, M. W.; Nagao, K.; Nishiizumi, K.</p> <p>2014-12-01</p> <p>Long-lived radionuclides, such as 10Be, <span class="hlt">26</span><span class="hlt">Al</span>, and <span class="hlt">36</span><span class="hlt">Cl</span>, are produced by cosmic rays in surficial materials on Earth, and used for determinations of cosmic-ray exposure ages and erosion rates. Quartz and limestone are routinely used as the target minerals for these geomorphological studies. Magnetite also contains target elements that produce abundant cosmogenic nuclides when exposed to the cosmic rays. Magnetite has several notable merits that enable the measurement of cosmogenic nuclides: (1) the target elements for production of cosmogenic nuclides in magnetite comprise the dominant mineral form of magnetite, Fe3O4; (2) magnetite can be easily isolated, using a magnet, after rock milling; (3) multiple cosmogenic nuclides are produced by exposure of magnetite to cosmic-ray secondaries; and (4) cosmogenic nuclides produced in the rock containing the magnetite, but not within the magnetite itself, can be separated using nitric acid and sodium hydroxide leaches. As part of this initial study, magnetite was separated from a basaltic sample collected from the Atacama Desert in Chili (2,995 m). Then Be, Al, Cl, Ca, and Mn were separated from ~2 g of the purified magnetite. We measured cosmogenic 10Be, <span class="hlt">26</span><span class="hlt">Al</span>, and <span class="hlt">36</span><span class="hlt">Cl</span> concentrations in the magnetite by accelerator mass spectrometry at PRIME Lab, Purdue University. Cosmogenic 3He and 21Ne concentrations of aliquot of the magnetite were measured by mass spectrometry at the University of Tokyo. We also measured the nuclide concentrations from magnetite collected from a mine at Ishpeming, Michigan as a blank. The 10Be and <span class="hlt">36</span><span class="hlt">Cl</span> concentrations as well as 3He concentration produce concordant cosmic ray exposure ages of ~0.4 Myr for the Atacama basalt. However, observed high <span class="hlt">26</span><span class="hlt">Al</span> and 21Ne concentrations attribute to those nuclides incorporation from silicate impurity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1996LPI....27..357F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1996LPI....27..357F"><span id="translatedtitle">Cosmogenic-radionuclide Profile of the Mocs Meteorite Strewnfield</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ferko, T. E.; Lipschutz, M. E.</p> <p>1996-03-01</p> <p>Cosmic-ray produced nuclides were measured in samples from eight pieces of the L5-6 chondrite Mocs from known locations in the strewnfield. We measured 10Be and <span class="hlt">26</span><span class="hlt">Al</span> in the bulk phase along with <span class="hlt">36</span><span class="hlt">Cl</span> in both the metal and silicate phases. Relationships of the activities of these radionuclides from various meteorite pieces in the Mocs strewnfield provide new insight into the association of meteorite fragments to each other in the pre-atmospheric parent body. Results suggest a >2pi irradiation for the Mocs meteoroid which was less than 1 meter in radius.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/783154','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/783154"><span id="translatedtitle">NEW CALCULATION OF RADIOACTIVE SECONDARIES IN COSMIC RAYS</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>I. V. MOSKALENKO; S. G. MASHNIK; A. W. STRONG</p> <p>2001-06-01</p> <p>We use a new version of our numerical model for particle propagation in the Galaxy to study radioactive secondaries. For evaluation of the production cross sections we use the Los Alamos compilation of all available experimental cross sections together with calculations using the improved Cascade-Exciton Model code CEM2k. Using the radioactive secondary ratios {sup <span class="hlt">26</span>}<span class="hlt">Al</span>/{sup 27}Al, {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>/Cl, {sup 54}Mn/Mn, we show how the improved cross-section calculations together with the new propagation code allow us to better constrain the size of the CR halo.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2000NIMPB.172..790H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000NIMPB.172..790H"><span id="translatedtitle">Cosmogenic in situ production of radionuclides: Exposure ages and erosion rates</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Heisinger, B.; Nolte, E.</p> <p>2000-10-01</p> <p>Experimental data for the cosmogenic in situ production of radionuclides and its depth dependence are used for two applications, the determination of exposure ages and of erosion rates. Concentrations of the long-lived radionuclides 10Be, 14C and <span class="hlt">26</span><span class="hlt">Al</span> in quartz are presented as function of exposure age, depth before exposure and erosion rate after exposure. It is shown that the cosmogenic production before exposure can introduce important corrections to the representation without consideration of pre-exposure production. Depth profiles of 10Be, 14C and <span class="hlt">26</span><span class="hlt">Al</span> in quartz and sulfur, of <span class="hlt">36</span><span class="hlt">Cl</span> in K 2O, CaCO 3, granite and concrete and of 53Mn in Fe 2O 3 are given as function of erosion rate. Consequences to determinations of neutron fluences in Hiroshima are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22370139','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22370139"><span id="translatedtitle">Light-element nucleosynthesis in a molecular cloud interacting with a supernova remnant and the origin of beryllium-10 in the protosolar nebula</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Tatischeff, Vincent; Duprat, Jean; De Séréville, Nicolas</p> <p>2014-12-01</p> <p> association, expanded during most of its adiabatic phase in an intercloud medium of density of about 1 H-atom cm{sup –3}, and eventually interacted with the presolar molecular cloud only during the radiative stage. This model naturally provides an explanation for the injection of other short-lived radionuclides of stellar origin into the cold presolar molecular cloud ({sup <span class="hlt">26</span>}<span class="hlt">Al</span>, {sup <span class="hlt">41</span>}<span class="hlt">Ca</span>, and {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>) and is in agreement with the solar system originating from the collapse of a molecular cloud shocked by a supernova blast wave.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16059873','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16059873"><span id="translatedtitle">Applications of accelerator mass spectrometry for pharmacological and toxicological research.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Brown, Karen; Tompkins, Elaine M; White, Ian N H</p> <p>2006-01-01</p> <p>The technique of accelerator mass spectrometry (AMS), known for radiocarbon dating of archeological specimens, has revolutionized high-sensitivity isotope detection in pharmacology and toxicology by allowing the direct determination of the amount of isotope in a sample rather than measuring its decay. It can quantify many isotopes, including <span class="hlt">26</span><span class="hlt">Al</span>, 14C, <span class="hlt">41</span><span class="hlt">Ca</span>, and 3H with detection down to attomole (10(-18)) amounts. Pharmacokinetic data in humans have been achieved with ultra-low levels of radiolabel. One of the most exciting biomedical applications of AMS with 14C-labeled potential carcinogens is the detection of modified proteins or DNA in tissues. The relationship between low-level exposure and covalent binding of genotoxic chemicals has been compared in rodents and humans. Such compounds include heterocyclic amines, benzene, and tamoxifen. Other applications range from measuring the absorption of <span class="hlt">26</span><span class="hlt">Al</span> to monitoring <span class="hlt">41</span><span class="hlt">Ca</span> turnover in bone. In epoxy-embedded tissue sections, high-resolution imaging of 14C label in cells is possible. The uses of AMS are becoming more widespread with the availability of instrumentation dedicated to the analysis of biomedical samples.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18215644','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18215644"><span id="translatedtitle">Critical comparison of radiometric and mass spectrometric methods for the determination of radionuclides in environmental, biological and nuclear waste samples.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hou, Xiaolin; Roos, Per</p> <p>2008-02-11</p> <p>The radiometric methods, alpha (alpha)-, beta (beta)-, gamma (gamma)-spectrometry, and mass spectrometric methods, inductively coupled plasma mass spectrometry, accelerator mass spectrometry, thermal ionization mass spectrometry, resonance ionization mass spectrometry, secondary ion mass spectrometry, and glow discharge mass spectrometry are reviewed for the determination of radionuclides. These methods are critically compared for the determination of long-lived radionuclides important for radiation protection, decommissioning of nuclear facilities, repository of nuclear waste, tracer application in the environmental and biological researches, these radionuclides include (3)H, (14)C, (<span class="hlt">36</span>)<span class="hlt">Cl</span>, (<span class="hlt">41</span>)<span class="hlt">Ca</span>, (59,63)Ni, (89,90)Sr, (99)Tc, (129)I, (135,137)Cs, (210)Pb, (226,228)Ra, (237)Np, (241)Am, and isotopes of thorium, uranium and plutonium. The application of on-line methods (flow injection/sequential injection) for separation of radionuclides and automated determination of radionuclides is also discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/18215644','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/18215644"><span id="translatedtitle">Critical comparison of radiometric and mass spectrometric methods for the determination of radionuclides in environmental, biological and nuclear waste samples.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hou, Xiaolin; Roos, Per</p> <p>2008-02-11</p> <p>The radiometric methods, alpha (alpha)-, beta (beta)-, gamma (gamma)-spectrometry, and mass spectrometric methods, inductively coupled plasma mass spectrometry, accelerator mass spectrometry, thermal ionization mass spectrometry, resonance ionization mass spectrometry, secondary ion mass spectrometry, and glow discharge mass spectrometry are reviewed for the determination of radionuclides. These methods are critically compared for the determination of long-lived radionuclides important for radiation protection, decommissioning of nuclear facilities, repository of nuclear waste, tracer application in the environmental and biological researches, these radionuclides include (3)H, (14)C, (<span class="hlt">36</span>)<span class="hlt">Cl</span>, (<span class="hlt">41</span>)<span class="hlt">Ca</span>, (59,63)Ni, (89,90)Sr, (99)Tc, (129)I, (135,137)Cs, (210)Pb, (226,228)Ra, (237)Np, (241)Am, and isotopes of thorium, uranium and plutonium. The application of on-line methods (flow injection/sequential injection) for separation of radionuclides and automated determination of radionuclides is also discussed. PMID:18215644</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22364021','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22364021"><span id="translatedtitle">ON THE INJECTION OF SHORT-LIVED RADIONUCLIDES FROM A SUPERNOVA INTO THE SOLAR NEBULA: CONSTRAINTS FROM THE OXYGEN ISOTOPES</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Liu, Ming-Chang</p> <p>2014-02-01</p> <p>Injection of short-lived radionuclides from a nearby core-collapse Type II supernova into the already-formed solar protoplanetary disk was proposed to account for the former presence of {sup <span class="hlt">26</span>}<span class="hlt">Al</span>, {sup <span class="hlt">41</span>}<span class="hlt">Ca</span>, and {sup 60}Fe in the early solar system inferred from isotopic analysis of meteoritic samples. One potential corollary of this ''late-injection'' scenario is that the disk's initial (pre-injection) oxygen isotopic composition could be significantly altered, as supernova material that carried the short-lived radionuclides would also deliver oxygen components synthesized in that given star. Therefore, the change in the oxygen isotopic composition of the disk caused by injection could in principle be used to constrain the supernova injection models. Previous studies showed that although supernova oxygen could result in a wide range of shifts in {sup 17}O/{sup 16}O and {sup 18}O/{sup 16}O of the disk, a couple of cases existed where the calculated oxygen changes in the disk would be compatible with the meteoritic and solar wind data. Recently, the initial abundances of {sup <span class="hlt">41</span>}<span class="hlt">Ca</span> and {sup 60}Fe in the solar system were revised to lower values, and the feasibility of supernova injection as a source for the three radionuclides was called into question. In this study, supernova parameters needed for matching {sup <span class="hlt">26</span>}<span class="hlt">Al</span>, {sup <span class="hlt">41</span>}<span class="hlt">Ca</span>, and {sup 60}Fe to their early solar system abundances were reinvestigated and then were used to infer the pre-injection O-isotope composition of the disk. The result suggested that a supernova undergoing mixing fallback might be a viable source for the three radionuclides.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014ApJ...781L..28L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014ApJ...781L..28L"><span id="translatedtitle">On the Injection of Short-lived Radionuclides from a Supernova into the Solar Nebula: Constraints from the Oxygen Isotopes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liu, Ming-Chang</p> <p>2014-02-01</p> <p>Injection of short-lived radionuclides from a nearby core-collapse Type II supernova into the already-formed solar protoplanetary disk was proposed to account for the former presence of <span class="hlt">26</span><span class="hlt">Al</span>, <span class="hlt">41</span><span class="hlt">Ca</span>, and 60Fe in the early solar system inferred from isotopic analysis of meteoritic samples. One potential corollary of this "late-injection" scenario is that the disk's initial (pre-injection) oxygen isotopic composition could be significantly altered, as supernova material that carried the short-lived radionuclides would also deliver oxygen components synthesized in that given star. Therefore, the change in the oxygen isotopic composition of the disk caused by injection could in principle be used to constrain the supernova injection models. Previous studies showed that although supernova oxygen could result in a wide range of shifts in 17O/16O and 18O/16O of the disk, a couple of cases existed where the calculated oxygen changes in the disk would be compatible with the meteoritic and solar wind data. Recently, the initial abundances of <span class="hlt">41</span><span class="hlt">Ca</span> and 60Fe in the solar system were revised to lower values, and the feasibility of supernova injection as a source for the three radionuclides was called into question. In this study, supernova parameters needed for matching <span class="hlt">26</span><span class="hlt">Al</span>, <span class="hlt">41</span><span class="hlt">Ca</span>, and 60Fe to their early solar system abundances were reinvestigated and then were used to infer the pre-injection O-isotope composition of the disk. The result suggested that a supernova undergoing mixing fallback might be a viable source for the three radionuclides.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMEP13C0851P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMEP13C0851P"><span id="translatedtitle">Chlorine-36 Production Rate Calibration by the CRONUS-Earth Project</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Phillips, F. M.; Marrero, S.; Stone, J. O.; Lifton, N. A.</p> <p>2012-12-01</p> <p>Among the cosmogenic nuclides commonly used for Quaternary geochronology and geomorphology (<span class="hlt">36</span><span class="hlt">Cl</span>, 10Be, <span class="hlt">26</span><span class="hlt">Al</span>, 3He, and 14C), the production rate of <span class="hlt">36</span><span class="hlt">Cl</span> has proved particularly difficult to calibrate because of the multiple nuclear reactions that lead to its production (3 major reactions and 5 minor ones). Achieving a consensus on the production constants for <span class="hlt">36</span><span class="hlt">Cl</span> has therefore been a major emphasis of the NSF-funded Cosmic Ray Produced Nuclide Systematics on Earth (CRONUS-Earth) Project. The most suitable for <span class="hlt">36</span><span class="hlt">Cl</span> calibration of the sites sampled by CRONUS-Earth proved to be ignimbrites from Younger Dryas-correlative moraines near the Quelccaya Ice Cap in Peru, basalts from the similar-aged Tabernacle Hill flow in Utah, and granodiorite boulders on a similar-aged moraine at Baboon Lakes in the Sierra Nevada, California. Production rates were estimated by minimizing <span class="hlt">36</span><span class="hlt">Cl</span> concentration residuals, with production scaled between the sites using the recently developed Lifton-Sato formulation. The scaling parameters employed were cut-off rigidity of 0 GV, solar modulation parameter of 587.4 MV, and air pressure of 1013.25 hPa; production-rate parameters obtained using this scaling approach are not directly comparable to those previously estimated using alternative scaling methods. This approach yielded sea-level high-latitude production rates of 55±2 atoms <span class="hlt">36</span><span class="hlt">Cl</span> (g Ca)-1 yr-1, 157±5 atoms <span class="hlt">36</span><span class="hlt">Cl</span> (g K)-1 yr-1, and 704±140 neutrons (g air)-1 yr-1. The results from the minimization did not meet tests for statistical significance and therefore the parameter-rate uncertainties could not be determined directly from the calibration data set. An independent secondary data set consisting of 82 samples from 16 localities and compiled from 7 separate published studies was therefore employed for this purpose. Average deviations of calculated <span class="hlt">36</span><span class="hlt">Cl</span> ages from independently determined ages increased from about 10% for samples where <span class="hlt">36</span><span class="hlt">Cl</span> production was nearly all from spallation</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=67703&keyword=preparation+AND+Physics&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=78811212&CFTOKEN=32996584','EPA-EIMS'); return false;" href="http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=67703&keyword=preparation+AND+Physics&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=78811212&CFTOKEN=32996584"><span id="translatedtitle">ALUMINUM AND PHOSPHORUS SEPARATION: APPLICATION TO PREPARATION OF TARGET FROM BRAIN TISSUE FOR <span class="hlt">26</span><span class="hlt">AL</span> DETERMINATION BY ACCELERATOR MASS SPECTROMETRY. (R825357)</span></a></p> <p><a target="_blank" href="http://oaspub.epa.gov/eims/query.page">EPA Science Inventory</a></p> <p></p> <p></p> <p>The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/10108632','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/10108632"><span id="translatedtitle">Accelerator mass spectrometry in biomedical research</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Vogel, J.S.; Turteltaub, K.W.</p> <p>1993-10-20</p> <p>Biological effects occur in natural systems at chemical concentrations of parts per billion (1:10{sup 9}) or less. Affected biomolecules may be separable in only milligram or microgram quantities. Quantification at attomole sensitivity is needed to study these interactions. AMS measures isotope concentrations to parts per 10{sup 13--15} on milligram-sized samples and is ideal for quantifying long-lived radioisotopic labels that are commonly used to trace biochemical pathways in natural systems. {sup 14}C-AMS has now been coupled to a variety of organic separation and definition technologies. The primary research investigates pharmacokinetics and genotoxicities of toxins and drugs at very low doses. Human subject research using AMS includes nutrition, toxicity and elemental balance studies. {sup 3} H, {sup <span class="hlt">41</span>}<span class="hlt">Ca</span> and {sup <span class="hlt">26</span>}<span class="hlt">Al</span> are also traced by AMS for fundamental biochemical kinetic research. Expansion of biomedical AMS awaits further development of biochemical and accelerator technologies designed specifically for these applications.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/211461','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/211461"><span id="translatedtitle">Radioanalytical technology for 10 CFR Part 61 and other selected radionuclides: Literature review</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Thomas, C.W.; Thomas, V.W.; Robertson, D.E.</p> <p>1996-03-01</p> <p>A comprehensive literature review and assessment was conducted to identify and evaluate radioanalytical technology and procedures used for measuring 10CFR61 radionuclides and other long-lived isotopes. This review evaluated radiochemical procedures currently in use at a number of laboratories in the US, as well as identifying new advanced methods and techniques which could be adapted for routine radiochemical analyses of low-level radioactive waste. The 10CFR61 radionuclides include {sup 14}C, {sup 60}Cl, {sup 59,63}Ni, {sup 90}Sr, {sup 94}Nb, {sup 99}Tc, {sup 129}I, {sup 137}Cs, and TRU isotopes with half lives greater than 5 years. Other low-level radionuclides of interest include {sup 7,10}Be, {sup <span class="hlt">26</span>}<span class="hlt">Al</span>, {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>, {sup 93}Mo, {sup 109,113m}Cd, and {sup 121m,126}Sn, which may be present in various types of waste streams from nuclear power stations.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_13 --> <div id="page_14" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="261"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.6116M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.6116M"><span id="translatedtitle">Using Multiple Cosmogenic Nuclides to Investigate Ice Elevation Changes in the Ellsworth Mountains, Antarctica</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Marrero, Shasta; Hein, Andy; Sugden, David; Woodward, John; Dunning, Stuart; Freeman, Stewart; Shanks, Richard</p> <p>2015-04-01</p> <p>Well-dated geologic data points provide important indicators that can be used for the reconstruction of ice sheet dynamics and as constraints in ice sheet models predicting future change. Cosmogenic nuclides, which accumulate in rocks exposed at the earth's surface, can be used to directly date the exposure age of the rock surfaces that have been created through glacial erosion or deposition. The technique requires a detailed understanding of the local geomorphology as well as awareness of the post-depositional processes that may affect the interpretation of exposure ages. Surface exposure ages (10Be, <span class="hlt">26</span><span class="hlt">Al</span>, 21Ne, and <span class="hlt">36</span><span class="hlt">Cl</span>) from local limestone bedrock and other glacially deposited exotic lithologies provide a history spanning from 0 to more than 1 million years in the Patriot, Independence, and Marble Hills in the southern Ellsworth Mountains, Antarctica. Using the new surface exposure ages combined with geomorphological mapping, we will discuss the implications for the glacial history of the southern Ellsworth Mountains.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.C13B0445M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.C13B0445M"><span id="translatedtitle">Ice Elevation Changes in the Ellsworth Mountains, Antarctica Using Multiple Cosmogenic Nuclides</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Marrero, S.; Hein, A.; Sugden, D.; Woodward, J.; Dunning, S.; Reid, K.</p> <p>2014-12-01</p> <p>Well-dated geologic data points provide important indicators that can be used for the reconstruction of ice sheet dynamics and as constraints in ice sheet models predicting future change. Cosmogenic nuclides, which accumulate in rocks exposed at the earth's surface, can be used to directly date the exposure age of the rock surfaces that have been created through glacial erosion or deposition. The technique requires a detailed understanding of the local geomorphology as well as awareness of the post-depositional processes that may affect the interpretation of exposure ages. Initial surface exposure ages (10Be, <span class="hlt">26</span><span class="hlt">Al</span>, 21Ne, and <span class="hlt">36</span><span class="hlt">Cl</span> ) from local limestone bedrock and other glacially deposited exotic lithologies provide a history spanning from 0 to 1.1 Ma in the Patriot, Independence, and Marble Hills in the southern Ellsworth Mountains, Antarctica. Using the new surface exposure ages combined with geomorphological mapping, we will discuss the implications for the glacial history of the southern Ellsworth Mountains.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22126771','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22126771"><span id="translatedtitle">ISOCHRONS IN PRESOLAR GRAPHITE GRAINS FROM ORGUEIL</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Zinner, Ernst; Jadhav, Manavi</p> <p>2013-05-10</p> <p>Primitive meteorites contain tiny dust grains that condensed in stellar outflows and explosions. These stardust grains can be extracted from their host meteorites and studied in detail in the laboratory. We investigated depth profiles of the Al-Mg, Ca-K, and Ti-Ca isotopic systems obtained during NanoSIMS isotopic analysis of presolar graphite grains from the CI carbonaceous meteorite Orgueil. Large {sup <span class="hlt">26</span>}<span class="hlt">Al</span>/{sup 27}Al, {sup <span class="hlt">41</span>}<span class="hlt">Ca</span>/{sup 40}Ca, and {sup 44}Ti/{sup 48}Ti ratios, inferred from {sup 26}Mg, {sup 41}K, and {sup 44}Ca excesses from the decay of the short-lived radioisotopes {sup <span class="hlt">26</span>}<span class="hlt">Al</span>, {sup <span class="hlt">41</span>}<span class="hlt">Ca</span>, and {sup 44}Ti, indicate a supernova (SN) origin. From the depth distribution of the radiogenic isotopes and the stable isotopes of their parent elements we constructed isochron-type correlation plots. The plots indicate quantitative retention of radiogenic {sup 26}Mg, {sup 41}K, and {sup 44}Ca in most grains. Deviations from straight lines in the Al-Mg and Ca-K plots can be explained by contamination with {sup 27}Al and isotopically normal Ca, respectively. For the Ti-Ca system in some grains, the lack of parent-daughter correlation indicates either redistribution of radiogenic {sup 44}Ca or heterogeneity in the initial {sup 44}Ti/{sup 48}Ti ratio. We also obtained Si isotopic depth profiles in three graphite grains with large {sup 29}Si and {sup 30}Si excesses, for which a SN origin has been proposed. In two grains no Si-rich subgrains are observed; in the third grain with an apparent Si-rich subgrain the anomalous Si isotopic ratios in the subgrain are the same as in the rest of the graphite host. Our studies show that by measuring depth profiles, information on presolar grains can be obtained that cannot be obtained by whole-grain analysis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008E%26PSL.270..308W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008E%26PSL.270..308W"><span id="translatedtitle">Meteoritic and bedrock constraints on the glacial history of Frontier Mountain in northern Victoria Land, Antarctica</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Welten, K. C.; Folco, L.; Nishiizumi, K.; Caffee, M. W.; Grimberg, A.; Meier, M. M. M.; Kober, F.</p> <p>2008-06-01</p> <p>In 2001, a small H4 chondrite, Frontier Mountain (FRO) 01149, was found on a glacially eroded surface near the top of Frontier Mountain, Antarctica, about 600 m above the present ice level. The metal and sulphides are almost completely oxidized due to terrestrial weathering. We used a chemical leaching procedure to remove weathering products, which contained atmospheric 10Be and <span class="hlt">36</span><span class="hlt">Cl</span> in a ratio similar to that found in Antarctic ice. The FRO 01149 meteorite has a terrestrial age of 3.0 ± 0.3 Myr based on the concentrations of the cosmogenic radionuclides 10Be, <span class="hlt">26</span><span class="hlt">Al</span> and <span class="hlt">36</span><span class="hlt">Cl</span>. This age implies that FRO 01149 is the oldest stony meteorite (fossil meteorites excluded) discovered on Earth. The noble gas cosmic ray exposure age of FRO 01149 is ~ 30 Myr. The meteorite thus belongs to the 33 Myr exposure age peak of H-chondrites. The bedrock surface on which FRO 01149 was found has wet-based glacial erosional features recording a former high-stand of the East Antarctic ice sheet. This ice sheet evidently overrode the highest peaks (> 2800 m a.s.l.) of the inland sector of the Transantarctic Mountains in northern Victoria Land. We argue that FRO 01149 was a local fall and that its survival on a glacially eroded bedrock surface constrains the age of the last overriding event to be older than ~ 3 Myr. The concentrations of in-situ produced cosmogenic 10Be, <span class="hlt">26</span><span class="hlt">Al</span> and 21Ne in a glacially eroded bedrock sample taken from near the summit of Frontier Mountain yield a surface exposure age of 4.4 Myr and indicate that the bedrock was covered by several meters of snow. The exposure age is also consistent with bedrock exposure ages of other summit plateaus in northern Victoria Land.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=547833','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=547833"><span id="translatedtitle">Short-lived chlorine-36 in a Ca- and Al-rich inclusion from the Ningqiang carbonaceous chondrite</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Lin, Yangting; Guan, Yunbin; Leshin, Laurie A.; Ouyang, Ziyuan; Wang, Daode</p> <p>2005-01-01</p> <p>Excesses of sulfur-36 in sodalite, a chlorine-rich mineral, in a calcium- and aluminum-rich inclusion from the Ningqiang carbonaceous chondrite linearly correlate with chorine/sulfur ratios, providing direct evidence for the presence of short-lived chlorine-36 (with a half-life of 0.3 million years) in the early solar system. The best inferred (<span class="hlt">36</span><span class="hlt">Cl</span>/35Cl)o ratios of the sodalite are ≈5 × 10-6. Different from other short-lived radionuclides, chlorine-36 was introduced into the inclusion by solid-gas reaction during secondary alteration. The alteration reaction probably took place at least 1.5 million years after the first formation of the inclusion, based on the correlated study of the <span class="hlt">26</span><span class="hlt">Al</span>-26Mg systems of the relict primary minerals and the alteration assemblages, from which we inferred an initial ratio of (<span class="hlt">36</span><span class="hlt">Cl</span>/35Cl)o > 1.6 × 10-4 at the time when calcium- and aluminum-rich inclusions formed. This discovery supports a supernova origin of short-lived nuclides [Cameron, A. G. W., Hoeflich, P., Myers, P. C. & Clayton, D. D. (1995) Astrophys. J. 447, L53; Wasserburg, G. J., Gallino, R. & Busso, M. (1998) Astrophys. J. 500, L189–L193], but presents a serious challenge for local irradiation models [Shu, F. H., Shang, H., Glassgold, A. E. & Lee, T. (1997) Science 277, 1475–1479; Gounelle, M., Shu, F. H., Shang, H., Glassgold, A. E., Rehm, K. E. & Lee, T. (2001) Astrophys. J. 548, 1051–1070]. Furthermore, the short-lived <span class="hlt">36</span><span class="hlt">Cl</span> may serve as a unique fine-scale chronometer for volatile-rock interaction in the early solar system because of its close association with aqueous and/or anhydrous alteration processes. PMID:15671168</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/15671168','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/15671168"><span id="translatedtitle">Short-lived chlorine-36 in a Ca- and Al-rich inclusion from the Ningqiang carbonaceous chondrite.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lin, Yangting; Guan, Yunbin; Leshin, Laurie A; Ouyang, Ziyuan; Wang, Daode</p> <p>2005-02-01</p> <p>Excesses of sulfur-36 in sodalite, a chlorine-rich mineral, in a calcium- and aluminum-rich inclusion from the Ningqiang carbonaceous chondrite linearly correlate with chorine/sulfur ratios, providing direct evidence for the presence of short-lived chlorine-36 (with a half-life of 0.3 million years) in the early solar system. The best inferred (<span class="hlt">36</span><span class="hlt">Cl</span>/35Cl)o ratios of the sodalite are approximately 5 x 10(-6). Different from other short-lived radionuclides, chlorine-36 was introduced into the inclusion by solid-gas reaction during secondary alteration. The alteration reaction probably took place at least 1.5 million years after the first formation of the inclusion, based on the correlated study of the <span class="hlt">26</span><span class="hlt">Al</span>-26Mg systems of the relict primary minerals and the alteration assemblages, from which we inferred an initial ratio of (<span class="hlt">36</span><span class="hlt">Cl</span>/35Cl)o > or = 1.6 x 10(-4) at the time when calcium- and aluminum-rich inclusions formed. This discovery supports a supernova origin of short-lived nuclides [Cameron, A. G. W., Hoeflich, P., Myers, P. C. & Clayton, D. D. (1995) Astrophys. J. 447, L53; Wasserburg, G. J., Gallino, R. & Busso, M. (1998) Astrophys. J. 500, L189-L193], but presents a serious challenge for local irradiation models [Shu, F. H., Shang, H., Glassgold, A. E. & Lee, T. (1997) Science 277, 1475-1479; Gounelle, M., Shu, F. H., Shang, H., Glassgold, A. E., Rehm, K. E. & Lee, T. (2001) Astrophys. J. 548, 1051-1070]. Furthermore, the short-lived <span class="hlt">36</span><span class="hlt">Cl</span> may serve as a unique fine-scale chronometer for volatile-rock interaction in the early solar system because of its close association with aqueous and/or anhydrous alteration processes. PMID:15671168</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2000M%26PS...35.1215F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000M%26PS...35.1215F"><span id="translatedtitle">Exposure history of the Mocs (L6) chondrite: A study of strewn field samples</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ferko, T. E.; Schultz, L.; Franke, L.; Bogard, D. D.; Garrison, D. H.; Hutchison, R.; Lipschutz, M. E.</p> <p>2000-11-01</p> <p>We measured cosmogenic radionuclides (10Be, <span class="hlt">26</span><span class="hlt">Al</span>, <span class="hlt">36</span><span class="hlt">Cl</span>) and noble gases (He, Ne and Ar) in 10 specimens of the L6 chondrite Mocs to determine the exposure history and pre-atmospheric relationship among fragments from known locations in the strewn field. Cosmogenic noble gas contents alone are consistent with a simple irradiation exposure of 15.2 Ma. However, Mocs has very low 22Ne/21Ne ratios indicative of deep burial in a large meteoroid, but radionuclide levels at saturation values typical for much smaller meteoroids: this paradox suggests a possible complex exposure. For the latter case, we propose a two-stage exposure history in which Mocs initially was buried deeply in a large object for 110 Ma followed by exposure in a 65 cm object for 10.5 Ma. Relative shielding was inferred from the measured 22Ne/21Ne ratios assuming constant 22Ne/21Ne production for all samples during the first stage. These shielding levels, which are supported by estimates based on <span class="hlt">36</span><span class="hlt">Cl</span> production by neutron capture, indicate a possible relationship between depth of samples in the Mocs meteoroid and fall location in the strewn field.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21513434','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21513434"><span id="translatedtitle">Can-AMS: The New Accelerator Mass Spectrometry Facility At The University Of Ottawa</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kieser, W. E.; Zhao, X.-L.; Clark, I. D.; Kotzer, T.; Litherland, A. E.</p> <p>2011-06-01</p> <p>The Canadian Centre for Accelerator Mass Spectrometry (AMS) at the University of Ottawa will be equipped with a new, 3 MV tandem accelerator with peripheral equipment for the analysis of elements ranging from tritium to the actinides. This facility, along with a wide array of support instrumentation recently funded by the Canada Foundation for Innovation, will be located in a new science building on the downtown campus of the University of Ottawa. In addition to providing the standard AMS measurements on {sup 14}C, {sup 10}Be, {sup <span class="hlt">26</span>}<span class="hlt">Al</span>, {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> and {sup 129}I for earth, environmental, cultural and biomedical sciences, this facility will incorporate the new technologies of anion isobar separation at low energies using RFQ chemical reaction cells for {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> and new heavy element applications, integrated sample combustion and gas ion source for biomedical and environmental {sup 14}C analysis and the use of novel target matrices for expanding the range of applicable elements and simplifying sample preparation, all currently being developed at IsoTrace. This paper will outline the design goals for the new facility, present some details of the new AMS technologies, in particular the Isobar Separator for Anions and discuss the design of the AMS system resulting from these requirements.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/303923','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/303923"><span id="translatedtitle">Center for accelerator mass spectrometry Lawrence Livermore National Laboratory</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Roberts, M.L.; Southon, J.R.; Proctor, I.D.</p> <p>1997-09-01</p> <p>The Center for Accelerator Mass Spectrometry (CAMS) at Lawrence Livermore National Laboratory (LLNL) is a multi-disciplinary research organization that conducts both technological and applications research. CAMS operates both an HVEC FN tandem and a NEC Model 5SDH-2 tandem accelerator. Using highly sensitive accelerator-based element and isotope detection methods, staff at CAMS collaborate with a broad scope of external and internal researchers to solve problems for LLNL, the University of California, the U.S. Department of Energy, and other academic, government, and industrial laboratories. The HVEC FN tandem is used by the LLNL Accelerator Mass Spectrometry (AMS) group. AMS is a technique that uses isotope ratio mass spectrometry at MeV energies to quantify long lived radioisotopes. For AMS, the FN tandem is operated under a distributed computer control system that makes possible rapid and precise switching between experimental configurations on a daily basis. The accelerator and beam lines are unshielded with radiation protection provided by a computer supervised radiation monitoring system and proximity shielding. With AMS, we routinely measure the isotopes {sup 3} H, {sup 7} Be, {sup 10} Be, {sup 14} C, {sup <span class="hlt">26</span>} <span class="hlt">Al</span>, {sup <span class="hlt">36</span>} <span class="hlt">Cl</span>, {sup <span class="hlt">41</span>} <span class="hlt">Ca</span>, {sup 59} Ni, and {sup 129} I at abundances as low as 1 part in 10{sup 15} . Research programs are as diverse as archaeology, dosimetry of carcinogens and mutagens, oceanic and atmospheric chemistry, paleoclimatology, and detection of signatures of nuclear fuel reprocessing for non-proliferation purposes. During the past year our AMS group has run approximately 20,000 research samples. The NEC Model 5SDH-2 tandem accelerator is used by the Ion Micro Analysis Group (IMAG), a joint collaboration between LLNL and Sandia National Laboratories/California in biological and materials science research. The 1.7 MV accelerator and an Oxford Microbeams Quadrupole Triplet Lens System are used to create a 3 MeV micron scale focused ion</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002NIMPB.190..177G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002NIMPB.190..177G"><span id="translatedtitle">The novel HVEE 5 MV Tandetron™</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gottdang, A.; Mous, D. J. W.; Haitsma, R. G.</p> <p>2002-05-01</p> <p>Recently, HVEE has extended the voltage range for its Tandetron™ accelerators from 3 MV terminal voltage to 5 MV terminal voltage with the development of an entirely new coaxial Tandetron™. The new 5 MV system is presently in the final test phase and will shortly be installed at the Universidad Autonoma de Madrid (Spain) as part of their new IBA facility. The all-solid-state power supply (parallel-fed Cockroft-Walton type) is constructed around the high-energy accelerator tubes, thereby avoiding the T-shaped tank that was so far characteristic for the HVEE Tandetrons™. During the design of the system special emphasis has been put to minimize the electrical field strength in the complete structure. Using three-dimensional electrostatic field simulations, we were able to identify possible hot spots and to reduce the maximum field strength to 80% compared to that of older designs. This reduction in field strength guarantees more reliable operation at or even above the guaranteed terminal voltage of 5 MV. The electrical power for beam transport is generated by a 10 kW version of a recently in-house developed range of all-solid-state drivers with output powers of up to 25 kW. Apart from IBA applications like heavy element ERDA and NRA, the system is very well suited for other applications like positron emission tomography, deep implants in semiconductors as well as accelerator mass spectrometry of various elements, including <span class="hlt">36</span><span class="hlt">Cl</span> and <span class="hlt">41</span><span class="hlt">Ca</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016cosp...41E.735G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016cosp...41E.735G"><span id="translatedtitle">First solar system solids to proto-planets: A Rapid growth in a few million years</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Goswami, Jitendranath</p> <p>2016-07-01</p> <p>First solar system solids to proto-planets: A Rapid growth in a few million years J. N. Goswami Physical Research Laboratory Ahmedabad-380009, India Collapse of a dense molecular cloud led to the formation of the proto-Sun surrounded by a high temperature gaseous nebula. The nebula settled down to the mid-plane and formation of the first solar system solids, refractory oxides and silicates, such as Corundum, Perovskite, Melilite took place, that was followed by formation of more common silicate minerals. Laboratory studies of primitive meteorites support this scenario and also provide evidence for correlated presence of several now-extinct short-lived nuclides (e.g. <span class="hlt">41</span><span class="hlt">Ca</span>, <span class="hlt">26</span><span class="hlt">Al</span>, 60Fe) at the time of formation of the first solar system solids. Presence of 60Fe in early solar system solids suggests injection of freshly synthesized nuclides from a stellar source (a supernova) into the proto-solar cloud that also triggered its collapse and led to formation of our solar system. Presence of <span class="hlt">41</span><span class="hlt">Ca</span> (half-life: 0.1Ma) in early solar system solids suggest a time scale of less than a million years for the collapse of the proto-solar cloud and formation of proto-Sun and the first solar system solids. The gradual evolution of larger solar system objects, up to planetesimals (represented by the asteroids), took place at a rapid pace within a time scale of a few million years. Some of the asteroids retain their pristine nature (e.g. parent bodies of carbonaceous chondrite), while others, underwent melting and differentiation due to internal heating. Harold Urey proposed radioactive <span class="hlt">26</span><span class="hlt">Al</span> as a possible heat source that was confirmed by experiment only in 1999. Irons and stony iron meteorites are fragments from core regions of differentiated asteroids. Extensive computer simulation studies suggest that an explosive stellar event (e.g. supernova) can indeed trigger the collapse of the proto-solar cloud and also inject freshly synthesized short-lived nuclides into it within a relatively</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3228481','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3228481"><span id="translatedtitle">Cosmochemical evidence for astrophysical processes during the formation of our solar system</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>MacPherson, Glenn J.; Boss, Alan</p> <p>2011-01-01</p> <p>Through the laboratory study of ancient solar system materials such as meteorites and comet dust, we can recognize evidence for the same star-formation processes in our own solar system as those that we can observe now through telescopes in nearby star-forming regions. High temperature grains formed in the innermost region of the solar system ended up much farther out in the solar system, not only the asteroid belt but even in the comet accretion region, suggesting a huge and efficient process of mass transport. Bi-polar outflows, turbulent diffusion, and marginal gravitational instability are the likely mechanisms for this transport. The presence of short-lived radionuclides in the early solar system, especially 60Fe, <span class="hlt">26</span><span class="hlt">Al</span>, and <span class="hlt">41</span><span class="hlt">Ca</span>, requires a nearby supernova shortly before our solar system was formed, suggesting that the Sun was formed in a massive star-forming region similar to Orion or Carina. Solar system formation may have been “triggered” by ionizing radiation originating from massive O and B stars at the center of an expanding HII bubble, one of which may have later provided the supernova source for the short-lived radionuclides. Alternatively, a supernova shock wave may have simultaneously triggered the collapse and injected the short-lived radionuclides. Because the Sun formed in a region where many other stars were forming more or less contemporaneously, the bi-polar outflows from all such stars enriched the local region in interstellar silicate and oxide dust. This may explain several observed anomalies in the meteorite record: a near absence of detectable (no extreme isotopic properties) presolar silicate grains and a dichotomy in the isotope record between <span class="hlt">26</span><span class="hlt">Al</span> and nucleosynthetic (nonradiogenic) anomalies. PMID:22106251</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22106251','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22106251"><span id="translatedtitle">Cosmochemical evidence for astrophysical processes during the formation of our solar system.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>MacPherson, Glenn J; Boss, Alan</p> <p>2011-11-29</p> <p>Through the laboratory study of ancient solar system materials such as meteorites and comet dust, we can recognize evidence for the same star-formation processes in our own solar system as those that we can observe now through telescopes in nearby star-forming regions. High temperature grains formed in the innermost region of the solar system ended up much farther out in the solar system, not only the asteroid belt but even in the comet accretion region, suggesting a huge and efficient process of mass transport. Bi-polar outflows, turbulent diffusion, and marginal gravitational instability are the likely mechanisms for this transport. The presence of short-lived radionuclides in the early solar system, especially (60)Fe, (<span class="hlt">26</span>)<span class="hlt">Al</span>, and (<span class="hlt">41</span>)<span class="hlt">Ca</span>, requires a nearby supernova shortly before our solar system was formed, suggesting that the Sun was formed in a massive star-forming region similar to Orion or Carina. Solar system formation may have been "triggered" by ionizing radiation originating from massive O and B stars at the center of an expanding HII bubble, one of which may have later provided the supernova source for the short-lived radionuclides. Alternatively, a supernova shock wave may have simultaneously triggered the collapse and injected the short-lived radionuclides. Because the Sun formed in a region where many other stars were forming more or less contemporaneously, the bi-polar outflows from all such stars enriched the local region in interstellar silicate and oxide dust. This may explain several observed anomalies in the meteorite record: a near absence of detectable (no extreme isotopic properties) presolar silicate grains and a dichotomy in the isotope record between (<span class="hlt">26</span>)<span class="hlt">Al</span> and nucleosynthetic (nonradiogenic) anomalies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001M%26PS...36.1479L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001M%26PS...36.1479L"><span id="translatedtitle">Exposure History of the St-Robert (H5) Fall</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Leya, I.; Wieler, R.; Aggrey, K.; Herzog, G. F.; Schnabel, C.; Metzler, K.; Hildebrand, A. R.; Bouchard, M.; Jull, A. J. T.; Andrews, H. R.; Wang, M.-S.; Ferko, T. E.; Lipschutz, M. E.; Wacker, J. F.; Neumann, S.; Michel, R.</p> <p>2001-11-01</p> <p>The compositionally typical H5 chondrite St-Robert has an exposure age, 7.8 Ma, indistinguishable from that of the main cluster of H-chondrites. Small values of the cosmogenic 22Ne/21Ne ratio in interior samples imply a preatmospheric radius on the order of 40 cm. Sample depths based on tracks and the production rates of Bhattacharya et al. (1973) range from 6 to ~40 cm and are generally larger than depths estimated from published 60Co activities, perhaps because the track production rates adopted are too high. Depth profiles of the production rates of 14C, <span class="hlt">36</span><span class="hlt">Cl</span>, <span class="hlt">26</span><span class="hlt">Al</span>, 10Be, and 21Ne in stony material show increases with depth and reach levels 5% to 15% higher than expected from modeling calculations. The maximum concentrations in St-Robert are, however, generally comparable to those measured for the L5 chondrite, Knyahinya, whose preatmospheric radius of ~45 cm is thought to lead to the maximum possible production rates in chondrites. We infer that the pre-atmospheric radius of St-Robert was within 5 cm of the value that supports maximum production rates, i.e., 45+/-5 cm. With the measured density of 3.4+/-0.05 g/cm3 we obtain a pre-atmospheric mass of (1.3+/-0.4) ( 103 kg. The agreement of exposure ages for St-Robert obtained in several different ways and the similarity of the depth profiles for 14C, <span class="hlt">26</span><span class="hlt">Al</span>, 10Be, and 21Ne argue against a lengthy pre-exposure of St-Robert on the parent body and against a two-stage exposure after launch from the parent body. Following Morbidelli and Gladman (1998), we suggest that St-Robert was chipped from deep in its parent body, spent the next 7-8 Ma without undergoing a major collision, was nudged gradually into an orbital resonance with Jupiter, and then traveled quickly to Earth.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003TrGeo...1..347H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003TrGeo...1..347H"><span id="translatedtitle">Cosmic-ray Exposure Ages of Meteorites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Herzog, G. F.</p> <p>2003-12-01</p> <p>The classic idea of a cosmic-ray exposure (CRE) age for a meteorite is based on a simple but useful picture of meteorite evolution, the one-stage irradiation model. The precursor rock starts out on a parent body, buried under a mantle of material many meters thick that screens out cosmic rays. At a time ti, a collision excavates a precursor rock - a "meteoroid." The newly liberated meteoroid, now fully exposed to cosmic rays, orbits the Sun until a time tf, when it strikes the Earth, where the overlying blanket of air (and possibly of water or ice) again shuts out almost all cosmic rays (cf. Masarik and Reedy, 1995). The quantity tf-ti is called the CRE age, t. To obtain the CRE age of a meteorite, we measure the concentrations in it of one or more cosmogenic nuclides (Table 1), which are nuclides that cosmic rays produce by inducing nuclear reactions. Many shorter-lived radionuclides excluded from Table 1 such as 22Na (t1/2=2.6 yr) and 60Co (t1/2=5.27 yr) can also furnish valuable information, but can be measured only in meteorites that fell within the last few half-lives of those nuclides (see, e.g., Leya et al. (2001) and references therein). Table 1. Cosmogenic nuclides used for calculating exposure ages NuclideHalf-lifea (Myr) Radionuclides 14C0.005730 59Ni0.076 <span class="hlt">41</span><span class="hlt">Ca</span>0.1034 81Kr0.229 <span class="hlt">36</span><span class="hlt">Cl</span>0.301 <span class="hlt">26</span><span class="hlt">Al</span>0.717 10Be1.51 53Mn3.74 129I15.7 Stable nuclides 3He 21Ne 38Ar 83Kr 126Xe a http://www2.bnl.gov/ton. CRE ages have implications for several interrelated questions. From how many different parent bodies do meteorites come? How well do meteorites represent the population of the asteroid belt? How many distinct collisions on each parent body have created the known meteorites of each type? How often do asteroids collide? How big and how energetic were the collisions that produced meteoroids? What factors control the CRE age of a meteorite and how do meteoroid orbits evolve through time? We will touch on these questions below as we examine the data.By 1975, the CRE ages of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1995IJMSI.143..247F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1995IJMSI.143..247F"><span id="translatedtitle">Biomedical accelerator mass spectrometry</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Freeman, Stewart P. H. T.; Vogel, John S.</p> <p>1995-05-01</p> <p>Ultrasensitive SIMS with accelerator based spectrometers has recently begun to be applied to biomedical problems. Certain very long-lived radioisotopes of very low natural abundances can be used to trace metabolism at environmental dose levels ( [greater-or-equal, slanted] z mol in mg samples). 14C in particular can be employed to label a myriad of compounds. Competing technologies typically require super environmental doses that can perturb the system under investigation, followed by uncertain extrapolation to the low dose regime. <span class="hlt">41</span><span class="hlt">Ca</span> and <span class="hlt">26</span><span class="hlt">Al</span> are also used as elemental tracers. Given the sensitivity of the accelerator method, care must be taken to avoid contamination of the mass spectrometer and the apparatus employed in prior sample handling including chemical separation. This infant field comprises the efforts of a dozen accelerator laboratories. The Center for Accelerator Mass Spectrometry has been particularly active. In addition to collaborating with groups further afield, we are researching the kinematics and binding of genotoxins in-house, and we support innovative uses of our capability in the disciplines of chemistry, pharmacology, nutrition and physiology within the University of California. The field can be expected to grow further given the numerous potential applications and the efforts of several groups and companies to integrate more the accelerator technology into biomedical research programs; the development of miniaturized accelerator systems and ion sources capable of interfacing to conventional HPLC and GMC, etc. apparatus for complementary chemical analysis is anticipated for biomedical laboratories.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015NIMPB.361...13C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015NIMPB.361...13C"><span id="translatedtitle">Status report of the 1 MV AMS facility at the Centro Nacional de Aceleradores</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Calvo, Elena Chamizo; Santos, Francisco Javier; López-Gutiérrez, José María; Padilla, Santiago; García-León, Manuel; Heinemeier, Jan; Schnabel, Christoph; Scognamiglio, Grazia</p> <p>2015-10-01</p> <p>SARA (Spanish Accelerator for Radionuclides Analysis) was the first multielemental AMS facility installed in Spain in 2005. Since then it has been dedicated to the routine analysis of several radionuclides, such as 10Be, 14C, <span class="hlt">26</span><span class="hlt">Al</span>, 129I and Pu isotopes. Tests have been carried out with other isotopes, such as <span class="hlt">41</span><span class="hlt">Ca</span>, 236U and 237Np, and several changes have been made to the original facility to improve performance. First, an upgraded version of the ion source SO-110 has allowed us more stable measurement conditions for volatile elements (i.e. iodine), and a better general performance. Besides, changes in the target geometry have improved the ionization efficiency and long-term stability of the source output. Moreover, different software upgrades have been introduced to meet our routine operational needs. Finally, changing the movable Faraday-cup associated electronics now allows the measurement of smaller currents (in the range of pA), which has been key for the study of 236U/238U atomic ratio in environmental samples. Apart from these modifications it has to be noted that routine radiocarbon measurements have been moved to a Micadas system (200 kV) installed at CNA in 2012. In this paper we will illustrate the evolution of the facility up to now, and our future prospects will be introduced.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2000M%26PS...35..713M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000M%26PS...35..713M"><span id="translatedtitle">Cosmogenic radionuclides and noble gases in Antarctic H chondrites with high and normal natural thermoluminescence levels</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mokos, Jennifer L.; Franke, Luitgard; Scherer, Peter; Schultz, Ludolf; Lipschutz, Michael E.</p> <p>2000-07-01</p> <p>We report noble gas data for 37 H chondrites collected from the Allan Hills by EUROMET in the 1988/1989 Field Season. Among these are 16 specimens with high levels (>100 krad) of natural thermoluminescence (NTL), originally interpreted as signaling their derivation from a single meteoroid with an orbit that became Earth-crossing -~100 ka ago. One of these 16 is an H3 with a cosmic ray exposure age of ~33 Ma and clearly represents a separate fall. The other 15 H4-6 chondrites derive from 3 separate meteoroids, each of which is represented by a 5- or 6-member group. These groups have mean exposure ages of 3.7, 4.1 and 6.6 Ma: the middle-group members all contain solar Ne. The 2 younger groups also seem to each include a few H chondrites with normal NTL levels. Measurements of cosmogenic 10Be (1.5 Ma), <span class="hlt">26</span><span class="hlt">Al</span> (710 ka) and <span class="hlt">36</span><span class="hlt">Cl</span> (301 ka) in 14 of the high NTL chondrites indicate that all reflect a simple irradiation history. In contrast, many of a different, 38-member, randomly-selected suite of Antarctic H chondrites seem to have different cosmic ray irradiation histories. The 3.7 and 6.6 Ma groups from the 37-member Allan Hills suite come, respectively, from about 5-30 cm and about 5-10 cm depths in 80-125 cm and 60-125 cm-radius meteoroids.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002JGRE..107.5077F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002JGRE..107.5077F"><span id="translatedtitle">Chemical studies of H chondrites 11. Cosmogenic radionuclides in falls</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ferko, T. E.; Wang, M.-S.; Lipschutz, M. E.</p> <p>2002-10-01</p> <p>We measured the long-lived cosmogenic radionuclides 10Be, <span class="hlt">26</span><span class="hlt">Al</span>, and <span class="hlt">36</span><span class="hlt">Cl</span> in 47 H chondrite falls: 13 ``Cluster 1'' members, 9 ``Cluster 5'' members, and 25 random falls. From the date and time of fall, Clusters 1 and 5 were previously identified as possible coorbital meteoroid streams with distinctive thermal histories being confirmed by contents of volatile trace elements. Here, we use model data, including a three-radionuclide plot (10Bebulk/26Albulk versus 36Clmetal/26Albulk) and the multivariate statistical techniques of logistic regression and linear discriminant analysis to compare radionuclide levels and their utility to differentiate specific suites from other H chondrites. From our radionuclide results and from noble gas data from other workers, we identified 35 falls with simple irradiation histories and cosmic ray exposure ages >4 Ma. Eight others exhibit evidence for shorter (<=4 Ma) exposure, three of which had complex exposure histories (two having been reported by others previously); three others may have had such a history. In any event, the small proportion of H chondrite falls with complex exposure histories supports recent suggestions that they are not commonly encountered, as earlier workers suggested. Although cosmogenic radionuclides do not differentiate between Cluster 1 and a random set of H chondrites, H chondrites that lost 3He from solar heating are distinguishable from those with normal 3He levels.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1997M%26PS...32..769S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1997M%26PS...32..769S"><span id="translatedtitle">Allan Hills 88019: an Antarctic H-chondrite with a very long terrestrial age.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Scherer, P.; Schultz, L.; Neupert, U.; Knauer, M.; Neumann, S.; Leya, I.; Michel, R.; Mokos, J.; Lipschutz, M. E.; Metzler, K.; Suter, M.; Kubik, P. W.</p> <p>1997-11-01</p> <p>We have measured the concentrations of the cosmogenic radionuclides 10Be, <span class="hlt">26</span><span class="hlt">Al</span> and <span class="hlt">36</span><span class="hlt">Cl</span> (half-lives 1.51 Ma, 716 ka, 300 ka, respectively) in two different laboratories by AMS techniques, as well as concentrations and isotopic compositions of stable helium, neon and argon in the Antarctic H-chondrite Allan Hills 88019. In addition, nuclear track densities were measured. From these results it is concluded that the meteoroid ALH 88019 had a pre-atmospheric radius of (20 ( 5) cm and a shielding depth for the analyzed samples of between 4 and 8 cm. Using calculated and experimentally determined production rates of cosmogenic nuclides, an exposure age of about 40 Ma is obtained from cosmogenic 21Ne and 38Ar. The extremely low concentrations of radionuclides are explained by a very long terrestrial age for this meteorite of (2.2 ( 0.4) Ma. A similarly long terrestrial age was found so far only for the Antarctic L-chondrite Lewis Cliff 86360. Such long ages establish one boundary condition for the history of meteorites in Antarctica.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_14 --> <div id="page_15" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="281"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20050185664','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20050185664"><span id="translatedtitle">Numerical Model for Cosmic Rays Species Production and Propagation in the Galaxy</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Farahat, Ashraf; Zhang, Ming; Rassoul, Hamid; Connell, J. J.</p> <p>2005-01-01</p> <p>In recent years, considerable progress has been made in studying the propagation and origin of cosmic rays, as new and more accurate data have become available. Many models have been developed to study cosmic ray interactions and propagation showed flexibility in resembling various astrophysical conditions and good agreement with observational data. However, some astrophysical problems cannot be addressed using these models, such as the stochastic nature of the cosmic rays source, small-scale structures and inhomogeneities in the interstellar gas that can affect radioactive secondary abundance in cosmic rays. We have developed a new model and a corresponding computer code that can address some of these limitations. The model depends on the expansion of the backward stochastic solution of the general diffusion transport equation (Zhang 1999) starting from an observer position to solve a group of diffusion transport equations each of which represents a particular element or isotope of cosmic ray nuclei. In this paper we are focusing on key abundance ratios such as B/C, sub-Fe/Fe, (10)Be/(9)Be, (<span class="hlt">26</span>)<span class="hlt">Al</span>/(27)Al, (<span class="hlt">36</span>)<span class="hlt">Cl</span>/(37)Cl and (54)Mn/(55)Mn, which all have well established cross sections, to evaluate our model. The effect of inhomogeneity in the interstellar medium is investigated. The contribution of certain cosmic ray nuclei to the production of other nuclei is addressed. The contribution of various galactic locations to the production of cosmic ray nuclei observed at solar system is also investigated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012M%26PS...47..186W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012M%26PS...47..186W"><span id="translatedtitle">Cosmic-ray exposure age and preatmospheric size of the Bunburra Rockhole achondrite</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Welten, Kees C.; Meier, Matthias M. M.; Caffee, Marc W.; Laubenstein, Matthias; Nishizumi, Kunihiko; Wieler, Rainer; Bland, Phil A.; Towner, Martin C.; Spurný, Pavel</p> <p>2012-02-01</p> <p>Bunburra Rockhole is the first meteorite fall photographed and recovered by the Desert Fireball Network in Australia. It is classified as an ungrouped achondrite similar in mineralogical and chemical composition to eucrites, but it has a distinct oxygen isotope composition. The question is if achondrites like Bunburra Rockhole originate from the same parent body as the howardite-eucrite-diogenite (HED) meteorites or from several separate, differentiated parent bodies. To address this question, we measured cosmogenic radionuclides and noble gases in the Bunburra Rockhole achondrite. The short-lived radionuclides 22Na and 54Mn confirm that Bunburra Rockhole is a recent fall. The concentrations of 10Be, <span class="hlt">26</span><span class="hlt">Al</span> and <span class="hlt">36</span><span class="hlt">Cl</span> as well as the 22Ne/21Ne ratio indicate that Bunburra Rockhole was a relatively small object (R approximately 15 cm) in space, consistent with the photographic fireball observations. The cosmogenic 38Ar concentration yields a cosmic-ray exposure (CRE) age of 22 ± 3 Myr, whereas 21Ne and 3He yield approximately 30% and approximately 60% lower ages, respectively, due to loss of cosmogenic He and Ne, mainly from plagioclase. With a CRE age of 22 Myr, Bunburra Rockhole is the first anomalous eucrite that overlaps with the main CRE peak of the HED meteorites. The radiogenic K-Ar age of 4.1 Gyr is consistent with the U-Pb age, while the young U,Th-He age of approximately 1.4 Gyr indicates that Bunburra Rockhole lost radiogenic 4He more recently.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007NIMPB.259...36M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007NIMPB.259...36M"><span id="translatedtitle">Multi-nuclide AMS performances at MALT</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Matsuzaki, Hiroyuki; Nakano, Chuichiro; Tsuchiya, Yoko (Sunohara); Kato, Kazuhiro; Maejima, Yuji; Miyairi, Yosuke; Wakasa, Sachi; Aze, Takahiro</p> <p>2007-06-01</p> <p>MALT (Micro Analysis Laboratory, Tandem accelerator, The University of Tokyo) is a service and research facility for elemental and isotopic micro-analysis using a tandem accelerator, which was constructed in 1991-1993 and has been in operation since 1994. Since then, AMS, NRA and PIXE systems have been developed and highly refined. The accelerator of MALT is a 5UD Pelletron™ tandem van de Graaf (produced by National Electrostatics Corporation, USA) and maximum 5 MV voltage is available. MALT is equipped with two MC-SNICS ion sources (one of them dedicated for 14C-AMS), a sequential injection system and multi-Faraday cup systems. These equipment are all indispensable for a high precision and high efficiency AMS system. At MALT, high quality AMS of 7Be, 10Be, 14C, <span class="hlt">26</span><span class="hlt">Al</span> has been available. Recently, a <span class="hlt">36</span><span class="hlt">Cl</span>-AMS system using a gas-filled magnet was also greatly refined, and a new 129I-AMS system was developed and shows good performance. Now MALT is the only facility with multi-nuclide AMS in the Asian area. Over 40 projects are running at MALT every year. The total accelerator operation time in the 2004 season was 6363 h. In November 2004, the total operation time of the pelletron chain system since the construction of MALT went over 40,000 h without replacement.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015NIMPB.361...63M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015NIMPB.361...63M"><span id="translatedtitle">The status of the AMS system at MALT in its 20th year</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Matsuzaki, Hiroyuki; Nakano, Chuichiro; Tsuchiya, Yoko S.; Ito, Seiji; Morita, Akira; Kusuno, Haruka; Miyake, Yasuto; Honda, Maki; Bautista VII, Angel T.; Kawamoto, Marina; Tokuyama, Hironori</p> <p>2015-10-01</p> <p>MALT (Micro Analysis Laboratory, Tandem accelerator, The University of Tokyo) was designed for a 'highly sensitive and precise elemental and isotopic microanalysis system' using an ion-beam generated by a Pelletron™ 5UD tandem accelerator. Currently, a multi-nuclide AMS (10Be, 14C, <span class="hlt">26</span><span class="hlt">Al</span>, <span class="hlt">36</span><span class="hlt">Cl</span>, 129I) system is available and shows good performance in both precision and sensitivity, and the accelerator serves for PIXE, NRA, ERDA/RBS measurements as well. The total operation time of the accelerator has been over 95,000 hours since the start of MALT, 20 years ago. After the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident, many projects related to 129I have been conducted. The retrospective reconstruction of the 131I distribution at the accident from 129I is one of the most important missions for dose evaluation of the residents. The accident-derived 129I is also quite useful as a tracer for the general iodine dynamics in the environment. As a new tool for environmental assessment related to nuclear activity, including the global fallout from past atmospheric nuclear bomb testing, effects from the spent fuel reprocessing plant, and nuclear accidents such as Chernobyl and FDNPP, a 236U-AMS system is now under development.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002AGUFM.U11A0002C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002AGUFM.U11A0002C"><span id="translatedtitle">Purdue Rare Isotope Measurement Laboratory</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Caffee, M.; Elmore, D.; Granger, D.; Muzikar, P.</p> <p>2002-12-01</p> <p>The Purdue Rare Isotope Measurement Laboratory (PRIME Lab) is a dedicated research and service facility for accelerator mass spectrometry. AMS is an ultra-sensitive analytical technique used to measure low levels of long-lived cosmic-ray-produced and anthropogenic radionuclides, and rare trace elements. We measure 10Be (T1/2 = 1.5 My), <span class="hlt">26</span><span class="hlt">Al</span> (.702 My), <span class="hlt">36</span><span class="hlt">Cl</span> (.301 My), and 129I (16 My), in geologic samples. Applications include dating the cosmic-ray-exposure time of rocks on Earth's surface, determining rock and sediment burial ages, measuring the erosion rates of rocks and soils, and tracing and dating ground water. We perform sample preparation and separation chemistries for these radio-nuclides for our internal research activities and for those external researchers not possessing this capability. Our chemical preparation laboratories also serve as training sites for members of the geoscience community developing these techniques at their institutions. Research at Purdue involves collaborators among members of the Purdue Departments of Physics, Earth and Atmospheric Sciences, Chemistry, Agronomy, and Anthropology. We also collaborate and serve numerous scientists from other institutions. We are currently in the process of modernizing the facility with the goals of higher precision for routinely measured radio-nuclides, increased sample throughput, and the development of new measurement capabilities for the geoscience community.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007GGG.....8.8003V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007GGG.....8.8003V"><span id="translatedtitle">CosmoCalc: An Excel add-in for cosmogenic nuclide calculations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vermeesch, Pieter</p> <p>2007-08-01</p> <p>As dating methods using Terrestrial Cosmogenic Nuclides (TCN) become more popular, the need arises for a general-purpose and easy-to-use data reduction software. The CosmoCalc Excel add-in calculates TCN production rate scaling factors (using Lal, Stone, Dunai, and Desilets methods); topographic, snow, and self-shielding factors; and exposure ages, erosion rates, and burial ages and visualizes the results on banana-style plots. It uses an internally consistent TCN production equation that is based on the quadruple exponential approach of Granger and Smith (2000). CosmoCalc was designed to be as user-friendly as possible. Although the user interface is extremely simple, the program is also very flexible, and nearly all default parameter values can be changed. To facilitate the comparison of different scaling factors, a set of converter tools is provided, allowing the user to easily convert cut-off rigidities to magnetic inclinations, elevations to atmospheric depths, and so forth. Because it is important to use a consistent set of scaling factors for the sample measurements and the production rate calibration sites, CosmoCalc defines the production rates implicitly, as a function of the original TCN concentrations of the calibration site. The program is best suited for 10Be, <span class="hlt">26</span><span class="hlt">Al</span>, 3He, and 21Ne calculations, although basic functionality for <span class="hlt">36</span><span class="hlt">Cl</span> and 14C is also provided. CosmoCalc can be downloaded along with a set of test data from http://cosmocalc.googlepages.com.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005NuPhA.758..276C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005NuPhA.758..276C"><span id="translatedtitle">The Search for Supernova Signatures in an Ice Core</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cole, A. L.; Boyd, R. N.; Davis, M. E.; Thompson, L. G.; Davis, A. M.; Lewis, R. S.; Zinner, E.</p> <p>2005-07-01</p> <p>It has been suggested that ice cores may preserve detectable enhancements of some terrestrially rare radioisotopes, 10Be, <span class="hlt">26</span><span class="hlt">Al</span>, <span class="hlt">36</span><span class="hlt">Cl</span>, resulting from a near-Earth core-collapse supernova(SN) [J. Ellis, B.D. Fields and D.N. Schramm, Astrophys. J. 470 (1996) 1227]. Both 10Be and <span class="hlt">36</span><span class="hlt">Cl</span> are also produced by atmospheric cosmic ray spallation and hence are influenced by processes that modulate the Earth's cosmic ray flux. Previous studies [G.M. Raisbeck, F. Yiou, D. Bourles, C. Lorius, J. Jouzel and N. I. Barkov, Nature 326 (1987) 273], [L.G. Thompson, T. Yao, M.E. Davis, K.A. Henderson, E. Mosley-Thompson, P.-N. Lin, J. Beer, H.-A. Synal, J. Cole-Dai and J.F. Bolzan, Science 276 (1997) 1821] have suggested that enhancements occurred in the 10Be and <span class="hlt">36</span><span class="hlt">Cl</span> fluxes at ˜35 ky and at ˜60 ky for 10Be. Thus we have searched for potential SN condensates with <span class="hlt">26</span><span class="hlt">Al</span> amongst grains filtered from the 308.6m Guliya ice core recovered from the Qinghai-Tibetan plateau in China [L.G. Thompson, T. Yao, M.E. Davis, K.A. Henderson, E. Mosley-Thompson, P.-N. Lin, J. Beer, H.-A. Synal, J. Cole-Dai and J.F. Bolzan, Science 276 (1997) 1821].We searched for potential core-collapse SN condensate grains corundum (Al2O3), hibonite (CaAl12O19) and spinel (MgAl2O4) (see [D.S. Ebel and L. Grossman, Geochim. Cosmochim. Acta 65 (2001) 469]) in Guliya grain samples from the following time periods: ˜2-10 ky, ˜25-27 ky, ˜34-36 ky, ˜53-57 ky, ˜59-62 ky and ˜68-72 ky. These minerals are rare among terrestrial rocks and fine-grained atmospheric dust of terrestrial origin. Furthermore, they are insoluble in the acids employed in the sample preparation process and therefore separable from other minerals, such as silicates, that have high terrestrial abundances. Candidate SN condensate grains were identified among their terrestrial diluents employing a procedure developed at the University of Chicago for detecting presolar grains in meteoritic samples [S. Amari, R.S. Lewis and E. Anders, Geochim. Cosmochim</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/10052679','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/10052679"><span id="translatedtitle">The dosimetry system DS86 and the neutron discrepancy in Hiroshima--historical review, present status, and future options.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rühm, W; Kellerer, A M; Korschinek, G; Faestermann, T; Knie, K; Rugel, G; Kato, K; Nolte, E</p> <p>1998-12-01</p> <p>The historical development of the dosimetry systems for Hiroshima and Nagasaki is outlined from the time immediately after the A-bomb explosions to the publication of the dosimetry system DS86 in 1987, and the present status of the so-called Hiroshima neutron discrepancy is summarized. Several long-lived radionuclides are discussed with regard to their production by neutrons from the A-bomb explosions. With the exception of 63Ni, these radionuclides have not, up to now, been measured in samples from Hiroshima and Nagasaki. Two of them, 63Ni in copper samples and 39Ar in granite samples, were predominantly produced by fast neutrons. 63Ni can be determined by accelerator mass spectrometry with a gas-filled analyzing magnet. It should be measurable, in the near future, in copper samples up to 1500 m from the hypocenter in Hiroshima. 39Ar can be measured in terms of low-level beta-counting. This should be feasible up to a distance of about 1000 m from the hypocenter. Three radionuclides, 10Be, 14C, and 59Ni, were produced predominantly by thermal neutrons with smaller fractions due to the epithermal and fast neutrons, which contribute increasingly more at larger distances from the hypocenter. State-of-the-art accelerator mass spectrometry is likely to permit the determination of 10Be close to the hypocenter and of 14C up to a distance of about 1000 m. 59Ni should be detectable up to a distance of about 1000 m in terms of accelerator mass spectrometry with a gas-filled magnet. The measurements of 10Be, 14C, 39Ar, 59Ni -- and potentially of 131Xe -- can be performed in the same granitic sample that was already analyzed for <span class="hlt">36</span><span class="hlt">Cl</span>, <span class="hlt">41</span><span class="hlt">Ca</span>, 6Co, 152Eu, and 154Eu. This will provide extensive information on the neutron spectrum at the specified location, and similarly complete analyses can conceivably be performed on granite samples at other locations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006E%26PSL.248..209F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006E%26PSL.248..209F"><span id="translatedtitle">Meteorites constrain the age of Antarctic ice at the Frontier Mountain blue ice field (northern Victoria Land)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Folco, L.; Welten, K. C.; Jull, A. J. T.; Nishiizumi, K.; Zeoli, A.</p> <p>2006-08-01</p> <p>We show that meteorites can provide chronological constraints upon the age of the ice cropping out at the Frontier Mountain meteorite trap (Antarctica) when their terrestrial age is placed in a glaciological context. Amongst the over 700 meteorites found so far, Frontier Mountain (FRO) 84001, 99028, 93005 and 93054 were most likely not wind-drifted across the ice field, since their masses (772-1665 g) are much heavier than the local ˜ 200 g wind transport threshold. The four meteorites were found along a stretch of ice where a representative section of the Frontier Mountain blue ice crops out. Based on the bedding of englacial tephra layers, the structure of the ice along the section appears to be essentially an up-glacier dipping monocline. The 14C terrestrial age of FRO 8401, 99028 and 93005 are 13 ± 2, 21 ± 3 and 27 ± 2 ky, respectively; the <span class="hlt">41</span><span class="hlt">Ca</span>/ <span class="hlt">36</span><span class="hlt">Cl</span> age of FRO 93054 is 40 ± 10 ky. The terrestrial ages of the four meteorites increase from the top to the bottom layers of the monocline. This geographic distribution is best explained by delivery of meteorites at the ice surface through the "ice-flow model" (i.e., englacial transport from the snow accumulation zone and exhumation in the blue ice area through ablation) rather than direct fall. Since the effect of ablation in decoupling terrestrial ages of meteorites and the age of the ice on which they sit must have been minor (most likely ≤ 7 ky) based on the local ice dynamics, we conclude that the age of the bulk of the ice body currently under ablation at Frontier Mountain is up to ˜ 50 ky old. This result has implications on both the meteorite concentrations mechanism at Frontier Mountain and the regional ice dynamics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/17643260','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/17643260"><span id="translatedtitle">DS02 fluence spectra for neutrons and gamma rays at Hiroshima and Nagasaki with fluence-to-kerma coefficients and transmission factors for sample measurements.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Egbert, Stephen D; Kerr, George D; Cullings, Harry M</p> <p>2007-11-01</p> <p>Fluence spectra at several ground distances in Hiroshima and Nagasaki are provided along with associated fluence-to-kerma coefficients from the Dosimetry System 2002 (DS02). Also included are transmission factors for calculating expected responses of in situ sample measurements of neutron activation products such as (32)P,(<span class="hlt">36</span>)<span class="hlt">Cl</span>,(39)Ar,(<span class="hlt">41</span>)<span class="hlt">Ca</span>, (60)Co,(63)Ni,(152)Eu, and (154)Eu. The free-in-air (FIA) fluences calculated in 2002 are available for 240 angles, 69 energy groups, 101 ground distances, 5 heights, 4 radiation source components, 2 cities. The DS02 code uses these fluences partitioned to a prompt and delayed portion, collapsed to 58 energy groups and restricted to 97 ground distances. This is because the fluence spectra were required to be in the same format that was used in the older Dosimetry System 1986 (DS86) computer code, of which the DS02 computer code is a modification. The 2002 calculation fluences and the collapsed DS02 code fluences are presented and briefly discussed. A report on DS02, which is available on the website at the Radiation Effects Research Foundation, provides tables and figures of the A-bomb neutron and gamma-ray output used as the sources in the 2002 radiation transport calculations. While figures illustrating the fluence spectra at several ground ranges are presented in the DS02 Report, it does not include any tables of the calculated fluence spectra in the DS02 report. This paper provides, at several standard distances from the hypocenter, the numerical information which is required to translate the FIA neutron fluences given in DS02 to a neutron activation measurement or neutron and gamma-ray soft-tissue dose. PMID:17643260</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1994PhDT.......218H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1994PhDT.......218H"><span id="translatedtitle">Spatial and Temporal Variations in CHLORINE-36 Deposition in the Northern United States</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hainsworth, Laura J.</p> <p></p> <p>Chlorine-36, a cosmogenic radioisotope, has been developed for use as a tracer in hydrological systems. The deposition of atmospheric ^{<span class="hlt">36</span>} <span class="hlt">Cl</span>, although of primary importance to hydrological applications, has not been well studied. To begin to address this problem, ^{<span class="hlt">36</span>}<span class="hlt">Cl</span> has been measured in monthly, wet-only, precipitation samples collected from February, 1991, to January, 1993, at the Elms Environmental Education Center in St. Mary's County, Maryland. In addition, bulk deposition samples were collected over a 1 y period at seven sites across the Northern United States and analyzed for ^{<span class="hlt">36</span>} <span class="hlt">Cl</span>. The mean, wet-only ^{<span class="hlt">36</span>} <span class="hlt">Cl</span>/Cl ratio for the 2 y sampling period is 68 +/- 19 (x10^{-15} ) and the mean ^{<span class="hlt">36</span>}<span class="hlt">Cl</span> concentration is 1.2 +/- 0.1 (x10 ^6) atoms/L. The ^ {<span class="hlt">36</span>}<span class="hlt">Cl</span> wet deposition flux data reveal a distinct seasonal deposition pattern, with peaks occurring in March and April. This pattern is attributed to stratospheric/tropospheric exchange. The mean ^{<span class="hlt">36</span>}<span class="hlt">Cl</span> wet deposition flux is 38.2 +/- 5 atoms/m^2s. Comparison between wet-only and bulk deposition samples indicates that the difference accounts for approximately 25% of the total ^{<span class="hlt">36</span>}<span class="hlt">Cl</span> deposition flux at the Elms site. A new model, using ^{90} Sr to predict the ^{<span class="hlt">36</span>} <span class="hlt">Cl</span> deposition pattern, is developed to predict ^{<span class="hlt">36</span>}<span class="hlt">Cl</span>/Cl ratios across the United States. Chlorine-<span class="hlt">36</span>/<span class="hlt">Cl</span> ratios in bulk deposition samples collected across the northern United States agree well with the model predictions. A mean global ^{<span class="hlt">36</span>}<span class="hlt">Cl</span> production rate of approximately 28 to 38 atoms/m^2s is indicated by these samples. A comparison between ^{<span class="hlt">36</span> }<span class="hlt">Cl</span> concentrations in the Aquia and Magothy aquifers in southern Maryland and bulk deposition samples collected at the Elms, MD, site indicated that modern precipitation can account for the ^{<span class="hlt">36</span>}<span class="hlt">Cl</span> content in the youngest water in these aquifers. Surface water samples from the Susquehanna River basin reveal ^{<span class="hlt">36</span>}<span class="hlt">Cl</span> and stable chloride concentrations an order of magnitude higher than in bulk</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1255183','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1255183"><span id="translatedtitle">The feasibility of isobaric suppression of <sup>26</sup>Mg via post-accelerator foil stripping for the measurement of <sup>26</sup>Al [The feasibility of isobaric suppression of 26Mg via post-accelerator foil stripping for the measurement of <span class="hlt">26</span><span class="hlt">Al</span>.</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Tumey, Scott J.; Brown, Thomas A.; Finkel, Robert C.; Rood, Dylan H.</p> <p>2012-09-13</p> <p>Most accelerator mass spectrometry measurements of <sup>26</sup>Al utilize the Al- ion despite lower source currents compared with AlO- since the stable isobar <sup>26</sup>Mg does not form elemental negative ions. A gas-filled magnet allows sufficient suppression of <sup>26</sup>Mg thus enabling the use of the more intense <sup>26</sup>AlO- ion. However, most AMS systems do not include a gas-filled magnet. We therefore explored the feasibility of suppressing <sup>26</sup>Mg by using a post-accelerator stripping foil. With this approach, combined with the use of alternative cathode matrices, we were able to suppress <sup>26</sup>Mg by a factor of twenty. This suppression was insufficient to enable the use of <sup>26</sup>AlO-, however further refinement of our system may permit its use in the future.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009ApJ...702.1118L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009ApJ...702.1118L"><span id="translatedtitle">New Titanium Isotope Data for Allende and Efremovka CAIs</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Leya, Ingo; Schönbächler, Maria; Krähenbühl, Urs; Halliday, Alex N.</p> <p>2009-09-01</p> <p>We measured the titanium (Ti) isotope composition, i.e., 50Ti/47Ti, 48Ti/47Ti, and 46Ti/47Ti, in five calcium-rich-aluminum-rich refractory inclusions (CAIs) from the oxidized CV3 chondrite Allende and in two CAIs from the reduced CV3 chondrite Efremovka. Our data indicate that CAIs are enriched in 50Ti/47Ti and 46Ti/47Ti and are slightly depleted in 48Ti/47Ti compared to normal Ti defined by ordinary chondrites, eucrites, ureilites, mesosiderites, Earth, Moon, and Mars. Some CAIs have an additional 50Ti excess of ~8ɛ relative to bulk carbonaceous chondrites, which are enriched in 50Ti by ~2ɛ relative to terrestrial values, leading to a total excess of ~10ɛ. This additional 50Ti excess is correlated with nucleosynthetic anomalies found in 62Ni and 96Zr, all indicating an origin from a neutron-rich stellar source. Bulk carbonaceous chondrites show a similar trend, however, the extent of the anomalies is either less than or similar to the smallest anomalies seen in CAIs. Mass balance calculations suggest that bulk Allende Ti possibly consists of a mixture of at least two Ti components, anomalous Ti located in CAIs and a normal component possibly for matrix and chondrules. This argues for a heterogeneous distribution of Ti isotopes in the solar system. The finding that anomalous Ti is concentrated in CAIs suggests that CAIs formed in a specific region of the solar system and were, after their formation, not homogeneously redistributed within the solar system. Combining the CAI data with improved model predictions for early solar system irradiation effects indicates that a local production scenario for the relatively short lived radionuclides can be excluded, because the production of, e.g., 10Be, <span class="hlt">26</span><span class="hlt">Al</span>, and <span class="hlt">41</span><span class="hlt">Ca</span>, would result in a significant collateral shift in Ti isotopes, which is not seen in the measured data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005ASPC..341..548J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005ASPC..341..548J"><span id="translatedtitle">The Birth of the Solar System in a Molecular Cloud: Evidence from the Isotopic Pattern of Short-lived Nuclides in the Early Solar System</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jacobsen, S. B.</p> <p>2005-12-01</p> <p>A good positive correlation between the initial solar abundances of short-lived (now extinct) nuclides (when normalized to their nucleosynthetic production ratios) and their mean lifetimes on a logarithmic plot has been well known for some time. Here I show that: (i) the slope for short-lived nuclides in the average interstellar medium in such a diagram is always 1. (ii) for molecular clouds, the slope is expected to be 2 or slightly less than 2 for a model where the molecular clouds are at a steady state and slowly exchange matter with the remaining interstellar medium. The existing data suggest a residence time of ˜ 6 x107 yrs for the matter present in molecular clouds. (iii) the intercept depends on (1) the residence time of matter in molecular clouds, (2) the mass fraction of the interstellar medium that is in molecular clouds, (3) the age of the galaxy and (4) the ratio of the time-average nucleosynthtic production rate and the production rate at the time of solar system formation. (iv) the abundances of 53Mn, 182Hf, 244Pu and 146Sm in the early solar system are likely formed by the same type of supernova sources (SNII?) over the history of our galaxy, while 129I (and possibly 107Pd) were produced in a different type of supernova sources (SNIa?) with the production rate skewed toward the early history of our galaxy. The abundances of these nuclides most likely characterize the average ISM values modified during their residence in the molecular cloud complex where the solar system formed. The abundances of <span class="hlt">26</span><span class="hlt">Al</span>, <span class="hlt">41</span> <span class="hlt">Ca</span> and 60Fe are too high to be of galactic production; these must be a contamination from young stellar sources that formed within the proto-Solar molecular cloud. These young sources could not have contributed significant quantities of 53Mn, 182Hf, 244Pu and 146Sm or 129I and thus were dissimilar to typical supernova sources.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/10123679','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/10123679"><span id="translatedtitle">AMS beyond 2000</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Davis, J.C.</p> <p>1993-12-28</p> <p>The occasion of this conference, the Sixth International Conference on Accelerator Mass Spectrometry, falls sixteen years after the remarkable triple simultaneous discovery of this powerful isotopic measurement. In the interval since the Fifth Conference in Paris in 1991, new facilities of both large and small size have become fully operational, achieving impressive gains in both measurement throughput and precision. The purpose of this short review is to extrapolate from recent gains and experience and to project the status of the field beyond the coming millennial date. AMS achieved instant application in archaeology and the geosciences and its early growth was stimulated by the excitement caused by the early results. The ability to obtain an accurate radiocarbon date with a sample one thousand times smaller than possible with scintillation or gas counting, the ability to trace {sup 14}CO{sub 2} in sea water with a similar thousand fold shrinkage in sample size, and the wide utility of {sup 10}Be, {sup <span class="hlt">26</span>}<span class="hlt">Al</span>, {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>, and {sup 129}I as tracers and chronometers of erosion, hydrology and paleoclimate were sufficient to drive the partial conversion of existing accelerators and the construction of new dedicated ones. These applications remain the core of the present field and continue to justify its growth. The past few years, however, have seen developments in new fields. Biomedicine, chemical kinetics, materials science, forensic dosimetry, and arms control/counter proliferation have been explored. These applications have varying promise and will influence development of AMS programs in new ways in the future.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.P23B3991F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.P23B3991F"><span id="translatedtitle">Observation of 23 Supernovae that Exploded <300 pc from Earth During the Past 300 kyr in the Radiocarbon and 10Be Cosmogenic Isotope Record</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Firestone, R. B.</p> <p>2014-12-01</p> <p>The global excess radiocarbon abundance record for the past 50 kyr can be entirely explained by the explosion of four supernovae 44, 37, 32, and 22 kyr ago less than 250 pc from Earth. Each supernova left a nearly identical signature beginning with a sudden increase at the time of the explosion, followed by a hiatus of 1500 years, and continuing with a sustained, 2000 year increase in radiocarbon from gamma rays produced by diffusive shock in the supernova remnant. For the past 18 kyr excess radiocarbon from SN22kyrBP, identified as the Vela supernova, has decayed with the 5700 year half-life of 14C. The absolute scale for radiocarbon abundance has been determined from the decay curve as Δ14C=5±2% in 1950. Small oscillations in the decay curve are shown to coincide with variations in Earth's Virtual Axial Dipole Moment (VADM). SN44kyrBP exploded approximately 110 pc from Earth doubling the radiocarbon abundance. These supernovae are confirmed in the 10Be, <span class="hlt">26</span><span class="hlt">Al</span>, <span class="hlt">36</span><span class="hlt">Cl</span> and nitrate geological records. An additional 19 supernovae are observed 50-300 kyr ago in the 10Be record. Using the Earth as a calorimeter I have determined that approximated 2×1049 ergs were released at the time of each supernova explosion and 1049-50 ergs afterwards, consistent with theoretical predictions. The background rate of radiocarbon productions from more distant sources was determined as 1.61 atoms/cm2s at the top of the atmosphere. Although little danger to life on Earth is expected from these supernovae, each of the recent events were shown to correlate with concurrent global warming of 3-4°C.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014ApJ...789...29F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014ApJ...789...29F"><span id="translatedtitle">Observation of 23 Supernovae That Exploded <300 pc from Earth during the past 300 kyr</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Firestone, R. B.</p> <p>2014-07-01</p> <p>Four supernovae (SNe), exploding <=300 pc from Earth, were recorded 44, 37, 32, and 22 kyr ago in the radiocarbon (14C) record during the past 50 kyr. Each SN left a nearly identical signature in the record, beginning with an initial sudden increase in atmospheric radiocarbon, when the SN exploded, followed by a hiatus of 1500 yr, and concluding with a sustained 2000 yr increase in global radiocarbon due to γ-rays produced by diffusive shock in the SN remnant (SNR). For the past 18 kyr excess radiocarbon has decayed with the 14C half-life. SN22kyrBP, is identified as the Vela SN that exploded 250 ± 30 pc from Earth. These SN are confirmed in the 10Be, <span class="hlt">26</span><span class="hlt">Al</span>, <span class="hlt">36</span><span class="hlt">Cl</span>, and NO_3^- geologic records. The rate of near-Earth SNe is consistent with the observed rate of historical SNe giving a galactic rate of 14 ± 3 kyr-1 assuming the Chandra Galactic Catalog SNR distribution. The Earth has been used as a calorimeter to determine that ≈2 × 1049 erg were released as γ-rays at the time of each SN explosion and ≈1050 erg in γ-rays following each SN. The background rate of 14C production by cosmic rays has been determined as 1.61 atoms cm-2 s-1. Approximately 1/3 of the cosmic ray energy produced by diffusive shock in the SNR was observed to be emitted as high-energy γ-rays. Analysis of the 10Be/9Be ratio in marine sediment identified 19 additional near-Earth SNe that exploded 50-300 kyr ago. Comparison of the radiocarbon record with global temperature variations indicated that each SN explosion is correlated with a concurrent global warming of ≈3°C-4°C.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5763853','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5763853"><span id="translatedtitle">Using cosmogenic isotopes to measure basin-scale rates of erosion</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Bierman, P.R.; Steig, E. . Dept. of Geology)</p> <p>1992-01-01</p> <p>The authors present a new and different approach to interpreting the abundance of in situ-produced cosmogenic nuclides such as [sup <span class="hlt">36</span>]<span class="hlt">Cl</span>, [sup <span class="hlt">26</span>]<span class="hlt">Al</span>, and [sup 10]Be. Unlike most existing models, which are appropriate for evaluating isotope concentrations on bedrock surfaces, this model can be used to interpret isotope concentration in fluvial sediment. Because sediment is a mixture of material derived from the entire drainage basin, measured isotope abundances can be used to estimate spatially-averaged rates of erosion and sediment transport. Their approach has the potential to provide geomorphologists with a relatively simple but powerful means by which to constrain rates of landscape evolution. The model considers the flux of cosmogenic isotopes into and out of various reservoirs. Implicit in model development are the assumptions that a geomorphic steady-state has been reached and that sampled sediment is spatially and temporally representative of all sediment leaving the basin. Each year, the impinging cosmic-ray flux produces a certain quantity of cosmogenic isotopes in the rock and soil of a drainage basin. For a basin in steady state, the outgoing isotope flux is also constant. They solve for the rate of mass loss as a function of isotope abundance in the sediment, the cosmic ray attenuation length, the isotope half life, and the effective isotope production rate. There are only a few published measurements of cosmogenic isotope abundance in sediment. They calculated model denudation rates for sediment samples from Zaire and central Texas. The denudation rates they calculated appear reasonable and are similar to those they have measured directly on granite landforms in Georgia and southeastern California and those calculated for the Appalachian Piedmont.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/803430','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/803430"><span id="translatedtitle">Exposure History of Shergottites Dar Al Gani 476/489/670/735 and Sayh Al Uhaymir 005</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Nishiizumi, N.; Caffee, M.; Jull, A.J.T.; Klandrud, S.E.</p> <p>2001-04-01</p> <p>Four basaltic shergottites, Dar al Gani (DaG) 476, 489, 670, and 735 were found in the Libyan Sahara [1-3]; two basaltic shergottites, Sayh al Uhaymir (SaU) 005 and 008 were found in Oman [4]. Recently SaU 051 was also recognized as a possible pair of SaU 005/008. Although the collection sites were different, the texture, bulk chemical compositions, and noble gas compositions of these shergottites are similar [e.g. 4]. However, cosmic-ray-produced noble gases alone cannot unambiguously constrain the irradiation history for these objects. From a combination of cosmogenic stable- and radionuclides, exposure histories, and ejection conditions from the hypothesized Martian parent body, and genetic relationships between the Martian meteorites can be determined. In addition to those nuclides produced by galactic cosmic rays (GCR) are those produced by solar cosmic rays (SCR). Radionuclides produced by SCRs reside in the uppermost few centimeters of extraterrestrial bodies and their presence in meteorites indicates the degree to which a meteorite has been ablated. Previous work shows ablation is less than 1-2 cm in at least three shergottites, ALH 77005, Shergotty, and EETA79001 [e.g. 5] and so it is possible some SCR signal may be observed in these meteorites. This suggests that the atmospheric entry velocity and/or entry angle of these shergottites is much lower than the velocity and/or entry angle of most ordinary chondrites. We report here preliminary results of cosmogenic nuclides, {sup 14}C (half-life = 5,730 yr), {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> (3.01 x 10{sup 5} yr), {sup <span class="hlt">26</span>}<span class="hlt">Al</span> (7.05 x 10{sup 5} yr), and {sup 10}Be(1.5 x 10{sup 6} yr).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1999AAS...194.1105C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1999AAS...194.1105C"><span id="translatedtitle">Testing the Role of Cosmic Ray Reacceleration in the Galaxy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Connell, J. J.; Simpson, J. A.</p> <p>1999-05-01</p> <p>Cosmic rays constitute a super-thermal gas of charged particles magnetically confined within the Galaxy. While propagating though the interstellar medium (ISM), cosmic ray nuclei undergo nuclear spallation reactions, producing both stable (i.e., Be and B) and unstable secondary nuclei. Consistent cosmic ray confinement times of ~ 20 Myr have been reported from measurements of the radioactive secondary isotopes (10) Be, (<span class="hlt">26</span>) <span class="hlt">Al</span>, (<span class="hlt">36</span>) <span class="hlt">Cl</span> and (54) Mn using data from the High Energy Telescope (HET) on the Ulysses spacecraft. It is generally accepted that Galactic cosmic rays of energy less than ~ 10(14) eV are accelerated by supernova shocks in the ISM. Reacceleration of existing cosmic rays in the ISM is implicit in interstellar shock acceleration models, but whether reacceleration plays a significant role in cosmic ray production and interstellar propagation is largely unknown. The abundances of secondary electron-capture isotopes provide a crucial test of cosmic ray reacceleration. Electron-capture is suppressed during interstellar propagation because cosmic ray nuclei are essentially stripped of their electrons. If, however, cosmic rays experience significant reacceleration, nuclei will have spent time at lower energies where electron pick-up, and hence electron capture, is more likely than at higher energies. Thus, electron capture secondary isotopes would be less abundant (and their daughters, more abundant) than otherwise predicted. The abundance ratio of (49) V to (51) V is a particularly sensitive test of this effect. The latest Ulysses HET data is used to address this problem. This research was supported in part by NASA/JPL Contract 955432 and NASA Grant NAG5-5179.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_15 --> <div id="page_16" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="301"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25409284','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25409284"><span id="translatedtitle">Distribution and chemical fate of ³⁶Cl-chlorine dioxide gas during the fumigation of tomatoes and cantaloupe.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Smith, D J; Ernst, W; Giddings, J M</p> <p>2014-12-01</p> <p>The distribution and chemical fate of (<span class="hlt">36</span>)<span class="hlt">Cl</span>-ClO2 gas subsequent to fumigation of tomatoes or cantaloupe was investigated as were major factors that affect the formation of chloroxyanion byproducts. Approximately 22% of the generated (<span class="hlt">36</span>)<span class="hlt">Cl</span>-ClO2 was present on fumigated tomatoes after a 2 h exposure to approximately 5 mg of (<span class="hlt">36</span>)<span class="hlt">Cl</span>-ClO2. A water rinse removed 14% of the radiochlorine while tomato homogenate contained ∼63% of the tomato radioactivity; 24% of the radiochlorine was present in the tomato stem scar area. Radioactivity in tomato homogenate consisted of (<span class="hlt">36</span>)<span class="hlt">Cl</span>-chloride (≥80%), (<span class="hlt">36</span>)<span class="hlt">Cl</span>-chlorate (5 to 19%), and perchlorate (0.5 to 1.4%). In cantaloupe, 55% of the generated (<span class="hlt">36</span>)<span class="hlt">Cl</span>-ClO2 was present on melons fumigated with 100 mg of (<span class="hlt">36</span>)<span class="hlt">Cl</span>-ClO2 for a 2 h period. Edible cantaloupe flesh contained no detectable radioactive residue (LOQ = 0.3 to 0.4 μg/g); >99.9% of radioactivity associated with cantaloupe was on the inedible rind, with <0.1% associated with the seed bed. Rind radioactivity was present as (<span class="hlt">36</span>)<span class="hlt">Cl</span>-chloride (∼86%), chlorate (∼13%), and perchlorate (∼0.6%). Absent from tomatoes and cantaloupe were (<span class="hlt">36</span>)<span class="hlt">Cl</span>-chlorite residues. Follow-up studies have shown that chlorate and perchlorate formation can be completely eliminated by protecting fumigation chambers from light sources.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26269327','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26269327"><span id="translatedtitle">Application of chlorine-36 technique in determining the age of modern groundwater in the Al-Zulfi province, Saudi Arabia.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Challan, Mohsen B</p> <p>2016-06-01</p> <p>The present study aims to estimate the residence time of groundwater based on bomb-produced (<span class="hlt">36</span>)<span class="hlt">Cl</span>. (<span class="hlt">36</span>)<span class="hlt">Cl</span>/Cl ratios in the water samples are determined by inductively coupled plasma mass spectrometry and liquid scintillation counting. (<span class="hlt">36</span>)<span class="hlt">Cl</span>/Cl ratios in the groundwater were estimated to be 1.0-2.0 × 10(-12). Estimates of residence time were obtained by comparing the measured bomb-derived (<span class="hlt">36</span>)<span class="hlt">Cl</span> concentrations in groundwater with the background reference. Dating based on a (<span class="hlt">36</span>)<span class="hlt">Cl</span> bomb pulse may be more reliable and sensitive for groundwater recharged before 1975, back as far as the mid-1950s. The above (<span class="hlt">36</span>)<span class="hlt">Cl</span> background concentration was deduced by determining the background-corrected Dye-3 ice core data from the frozen Arctic data, according to the estimated total (<span class="hlt">36</span>)<span class="hlt">Cl</span> resources. The residence time of 7.81 × 10(4) y is obtained from extrapolated groundwater flow velocity. (<span class="hlt">36</span>)<span class="hlt">Cl</span> concentration in groundwater does not reflect the input of bomb pulse (<span class="hlt">36</span>)<span class="hlt">Cl</span>, and it belongs to the era before 1950. PMID:26269327</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1999ARA%26A..37..239B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1999ARA%26A..37..239B"><span id="translatedtitle">Nucleosynthesis in Asymptotic Giant Branch Stars: Relevance for Galactic Enrichment and Solar System Formation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Busso, M.; Gallino, R.; Wasserburg, G. J.</p> <p></p> <p> synthesis requires penetration of small amounts of protons below the convective envelope, where they are captured by the abundant 12C forming a 13C-rich pocket. This penetration cannot be modeled in current evolutionary codes, but is treated as a free parameter. Future hydrodynamical studies of time dependent mixing will be required to attack this problem. Evidence of other insufficiencies in the current mixing algorithms is common throughout the evolution of low and intermediate mass stars, as is shown by the inadequacy of stellar models in reproducing the observations of CNO isotopes in red giants and in circumstellar dust grains. These observations require some circulation of matter between the bottom of convective envelopes and regions close to the H-burning shell (cool bottom processing). AGB stars are also discussed in the light of their possible contribution to the inventory of short-lived radioactivities that were found to be alive in the early solar system. We show that the pollution of the protosolar nebula by a close-by AGB star may account for concordant abundances of <span class="hlt">26</span><span class="hlt">Al</span>, <span class="hlt">41</span><span class="hlt">Ca</span>, 60Fe, and 107Pd. The AGB star must have undergone a very small neutron exposure, and be of small initial mass ([Image]). There is a shortage of <span class="hlt">26</span><span class="hlt">Al</span> in such models, that however remains within the large uncertainties of crucial reaction rates. The net <span class="hlt">26</span><span class="hlt">Al</span> production problem requires further investigation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008E%26PSL.275..154J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008E%26PSL.275..154J"><span id="translatedtitle">The distribution of meteoric Cl-36 in precipitation across Europe in spring 2007</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Johnston, Vanessa E.; McDermott, Frank</p> <p>2008-10-01</p> <p>The cosmogenic isotope <span class="hlt">36</span><span class="hlt">Cl</span> is a valuable tool for understanding many Earth system processes, but an improved knowledge of its spatial distribution at the Earth's surface is critical for several applications. Meteoric <span class="hlt">36</span><span class="hlt">Cl</span> fallout reflects complex interactions between atmospheric production, transport, and deposition processes, and predictive models require experimental validation. This study investigates, for the first time in a systematic way, the spatial distribution of meteoric <span class="hlt">36</span><span class="hlt">Cl</span> on a continental scale within the European landmass using precipitation samples collected during spring 2007. <span class="hlt">36</span><span class="hlt">Cl</span>/Cl ratios increase with distance inland and the new data exhibit a strong exponential relationship with δ18O values of precipitation ( RS = - 0.75), yielding a useful predictive framework for future studies. Precipitation events in central European regions are characterised by high <span class="hlt">36</span><span class="hlt">Cl</span>/Cl ratios, with a maximum measured in Lyon, France of 746 (± 134) × 10 - 15 . The new data confirm models for the dependence of <span class="hlt">36</span><span class="hlt">Cl</span> fallout on latitude, with the highest mean springtime fallout (53.6 atoms m - 2 s - 1 ) occurring in the 40-50°N latitudinal band, with sharp decreases in fallout in high latitude regions and more gradual decreases towards the lower latitudes. The <span class="hlt">36</span><span class="hlt">Cl</span> bomb pulse, introduced by thermonuclear weapon testing, predominantly in the 1950's, has persisted in the environment for c. 50 years, but the new data indicate that <span class="hlt">36</span><span class="hlt">Cl</span> fallout has now essentially returned to natural, pre-bomb values.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70025633','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70025633"><span id="translatedtitle">Chlorine-36 in groundwater of the United States: Empirical data</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Davis, S.N.; Moysey, S.; Cecil, L.D.; Zreda, M.</p> <p>2003-01-01</p> <p>Natural production of the radionuclide chlorine-36 (<span class="hlt">36</span><span class="hlt">Cl</span>) has provided a valuable tracer for groundwater studies. The nuclear industry, especially the testing of thermonuclear weapons, has also produced large amounts of <span class="hlt">36</span><span class="hlt">Cl</span> that can be detected in many samples of groundwater. In order to be most useful in hydrologic studies, the natural production prior to 1952 should be distinguished from more recent artificial sources. The object of this study was to reconstruct the probable preanthropogenic levels of <span class="hlt">36</span><span class="hlt">Cl</span> in groundwater in the United States. Although significant local variations exist, they are superimposed on a broad regional pattern of <span class="hlt">36</span><span class="hlt">Cl</span>/Cl ratios in the United States. Owing to the influence of atmospherically transported ocean salt, natural ratios of <span class="hlt">36</span><span class="hlt">Cl</span>/total Cl are lowest near the coast and increase to a maximum in the central Rocky Mountains of the United States.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1993Metic..28..400M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1993Metic..28..400M"><span id="translatedtitle">Cosmogenic Radionuclides in Antarctic Meteorites: Preliminary Results on Terrestrial Ages and Temporal Phenomena</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Michlovich, E.; Vogt, S.; Wolf, S. F.; Elmore, D.; Lipschutz, M. E.</p> <p>1993-07-01</p> <p>Since 1969, more than 15,000 meteorites have been recovered from various sites in Antarctica. Differences have been reported between the Antarctic populations and the population of non-Antarctic meteorites in volatile trace- element content, thermoluminescence properties, physical size, and relative distribution of meteorite type [1]. Lipschutz and Samuels [2] developed a method based upon multivariate linear and logistic regression that they applied to interpret trace-element content in Antarctic and non-Antarctic meteorites, showing that the two populations can be chemically distinguished. Since Antarctic meteorites have, on the whole, much longer terrestrial ages than non-Antarctic falls, such differences have been used to support the notion that the flux of meteorites sampled by the Earth has changed in the recent past. A subsequent study [3] showed a statistically significant difference in trace-element content between meteorites from Victoria Land and those found in Queen Maud Land, two groups that seem to have different terrestrial age distributions. Changes in meteorite flux patterns on the order of 60 yr are indicated from a study of Cluster 1 vs. non-Cluster 1 falls [4]. Rapid fluctuations would almost certainly require the existence of co-orbital meteoroid streams, an idea that has been criticized by some [5] on dynamical grounds. To quantify the discussion of a temporal dependence of meteorite flux patterns, and to continue systematic study of Antarctic meteorites, we have measured the contents of the cosmogenic radionuclides ^10Be and ^<span class="hlt">26</span><span class="hlt">Al</span> in the bulk phase, and ^<span class="hlt">36</span><span class="hlt">Cl</span> in the metal phase, of 40 Antarctic specimens that are from the same suite of samples analyzed in the trace-element studies and that were chosen to minimize any chances of paired meteorites. The means and standard deviations of ^10Be and ^<span class="hlt">26</span><span class="hlt">Al</span> activities are 16.4 +/- 3.5 and 48 +/- 8 dpm/kg respectively. Correction for cosmic ray exposure [6,7] and terrestrial ages allows us to estimate</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/17289228','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/17289228"><span id="translatedtitle">Transfer of chlorine from the environment to agricultural foodstuffs.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kashparov, V; Colle, C; Levchuk, S; Yoschenko, V; Svydynuk, N</p> <p>2007-01-01</p> <p>The factors governing chlorine transfer from Phaeozem and Greyzem soils to various important crop species (foodstuff and forage) were determined in natural conditions in the Kiev region of Ukraine. The stable chlorine concentration ratio (CR) values were the lowest in apple (0.5+/-0.3) and strawberry (2+/-1), higher in vegetables (5+/-3), seeds (15+/-7) and reached a maximum in straw (187+/-90). The average CR values of <span class="hlt">36</span><span class="hlt">Cl</span> were estimated for the most important crops using all experimental data on <span class="hlt">36</span><span class="hlt">Cl</span> and stable chlorine transfer into plants from various soils. It was experimentally shown that boiling potatoes in water leads to an equilibrium between <span class="hlt">36</span><span class="hlt">Cl</span> specific content in the water and moisture in the cooked potato. The <span class="hlt">36</span><span class="hlt">Cl</span> processing factor (PF) for boiling various foodstuffs is equal to the ratio of water mass in the cooked foodstuff to the total water mass (in the food and the decoction). <span class="hlt">36</span><span class="hlt">Cl</span> PF for cereal flour can be estimated as 1. The <span class="hlt">36</span><span class="hlt">Cl</span> processing factor for dairy products is equal to the ratio of residual water mass in the product to initial water mass in milk. At a <span class="hlt">36</span><span class="hlt">Cl</span> specific activity in soil of 1 Bq kg-1, the estimated annual dietary <span class="hlt">36</span><span class="hlt">Cl</span> intake into human organism (adult man) is about 10 kBq. Sixty to seventy percent of the above amount will be taken in via milk and dairy products, 7-16% via meat, 14-16% via bread and bakery items and 8-12% via vegetables. The highest annual <span class="hlt">36</span><span class="hlt">Cl</span> intake, 10.7 kBq, is predicted for 1-year-old children. The expected effective doses from annual <span class="hlt">36</span><span class="hlt">Cl</span> intake are higher for younger age groups, increasing from 0.008 mSv in adults to 0.12 mSv in 1-year-old children. PMID:17289228</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70020412','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70020412"><span id="translatedtitle">Chlorine-36 and the initial value problem</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Davis, S.N.; Cecil, D.; Zreda, M.; Sharma, Prakash</p> <p>1998-01-01</p> <p>Chlorine-36 is a radionuclide with a half-life of 3.01 ?? 105a. Most <span class="hlt">36</span><span class="hlt">Cl</span> in the hydrosphere originates from cosmic radiation interacting with atmospheric gases. Large amounts were also produced by testing thermonuclear devices during 1952-58. Because the monovalent anion, chloride, is the most common form of chlorine found in the hydrosphere and because it is extremely mobile in aqueous systems, analyses of both total Cl- as well as <span class="hlt">36</span><span class="hlt">Cl</span> have been important in numerous hydrologic studies. In almost all applications of <span class="hlt">36</span><span class="hlt">Cl</span>, a knowledge of the initial, or pre-anthropogenic, levels of <span class="hlt">36</span><span class="hlt">CL</span> is useful, as well as essential in some cases. Standard approaches to the determination of initial values have been to: (a) calculate the theoretical cosmogenic production and fallout, which varies according to latitude; (b) measure <span class="hlt">36</span><span class="hlt">CL</span> in present-day precipitation and assume that anthropogenic components can be neglected; (c) assume that shallow ground-water retains a record of the initial concentration; (d) extract <span class="hlt">36</span><span class="hlt">CL</span> from vertical depth profiles in desert soils; (e) recover <span class="hlt">36</span><span class="hlt">CL</span> from cores of glacial ice; and (f) calculate subsurface production of <span class="hlt">36</span><span class="hlt">CL</span> for water that has been isolated from the atmosphere for more than one million years. The initial value from soil profiles and ice cores is taken as the value that occurs directly below the depth of the easily defined bomb peak. All six methods have serious weaknesses. Complicating factors include <span class="hlt">36</span><span class="hlt">CL</span> concentrations not related to cosmogenic sources, changes in cosmogenic production with time, mixed sources of chloride in groundwater, melting and refrrezing of waterin glaciers, and seasonal groungwater recharge that does not contain average year-long concentrations of <span class="hlt">36</span><span class="hlt">Cl</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/943071','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/943071"><span id="translatedtitle">Extinct radioactivities and protosolar cosmic-rays : self-shielding and light elements.</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Gounelle, M.; Shu, F. H.; Shang, H.; Glassgold, A. E.; Rehm, K. E.; Lee, T.; Physics; Univ. of California at Berkeley; Inst. of Earth Science</p> <p>2001-02-20</p> <p>We study the effects of self-shielding in the X-wind model of protosolar cosmic-ray irradiation of early solar-system rocks. We adopt a two-component picture of protoCAIs consisting of cores with the elemental abundances of type B1 CAIs (calcium-aluminum-rich inclusions) and mantles of less refractory material. The cores have a power-law distribution of sizes between R{sub min} and R{sub max}. The mantles have a uniform thickness, whose value is chosen to bring the total inventory of elements at least as refractory as sulfur to cosmic abundances for the entire population of protoCAIs. Each object is irradiated with a fluence consistent with the product of their residence time in the reconnection ring and the flux of solar cosmic rays obtained by a scaling of impulsive flares from the hard X-rays observed from low-mass protostars. For R{sub min} in the 50 {mu}m regime and R{sub max} in the few centimeter regime, which corresponds to the range of sizes of observed CAIs in micrometeorites and chondrites, we recover approximately the canonical values quoted for the ratios {sup <span class="hlt">26</span>}<span class="hlt">Al</span>/{sup 27}Al, {sup 53}Mn/{sup 55}Mn, and {sup <span class="hlt">41</span>}<span class="hlt">Ca</span>/{sup 40}Ca in CV3 meteorites. Moreover, the excess {sup 138}La (denoted as {sup 138}La*) produced by proton bombardment of {sup 138}Ba lies within the CAI range obtained in the experiments of Shen et al. When we include fragmentation reactions that produce {sup 10}Be from the impact of protons, alphas, and {sup 3}He on the {sup 16}O that is bound up in rocks, we further obtain a level of {sup 10}Be/{sup 9}Be that agrees approximately with the report of McKeegan et al. for a CAI from the Allende meteorite. Similar calculations for the expected anomalies in the stable isotopes of lithium show rough consistency with the measured values and further support our interpretation. The value for {sup 10}Be/{sup 9}Be is particularly difficult to produce by any other astrophysical mechanism. Thus, the {sup 10}Be discovery greatly strengthens the case</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001ApJ...548.1051G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001ApJ...548.1051G"><span id="translatedtitle">Extinct Radioactivities and Protosolar Cosmic Rays: Self-Shielding and Light Elements</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gounelle, Matthieu; Shu, Frank H.; Shang, Hsien; Glassgold, A. E.; Rehm, K. E.; Lee, Typhoon</p> <p>2001-02-01</p> <p>We study the effects of self-shielding in the X-wind model of protosolar cosmic-ray irradiation of early solar-system rocks. We adopt a two-component picture of protoCAIs consisting of cores with the elemental abundances of type B1 CAIs (calcium-aluminum-rich inclusions) and mantles of less refractory material. The cores have a power-law distribution of sizes between Rmin and Rmax. The mantles have a uniform thickness, whose value is chosen to bring the total inventory of elements at least as refractory as sulfur to cosmic abundances for the entire population of protoCAIs. Each object is irradiated with a fluence consistent with the product of their residence time in the reconnection ring and the flux of solar cosmic rays obtained by a scaling of impulsive flares from the hard X-rays observed from low-mass protostars. For Rmin in the 50 μm regime and Rmax in the few centimeter regime, which corresponds to the range of sizes of observed CAIs in micrometeorites and chondrites, we recover approximately the canonical values quoted for the ratios <span class="hlt">26</span><span class="hlt">Al</span>/27Al, 53Mn/55Mn, and <span class="hlt">41</span><span class="hlt">Ca</span>/40Ca in CV3 meteorites. Moreover, the excess 138La (denoted as 138La*) produced by proton bombardment of 138Ba lies within the CAI range obtained in the experiments of Shen et al. When we include fragmentation reactions that produce 10Be from the impact of protons, alphas, and 3He on the 16O that is bound up in rocks, we further obtain a level of 10Be/9Be that agrees approximately with the report of McKeegan et al. for a CAI from the Allende meteorite. Similar calculations for the expected anomalies in the stable isotopes of lithium show rough consistency with the measured values and further support our interpretation. The value for 10Be/9Be is particularly difficult to produce by any other astrophysical mechanism. Thus, the 10Be discovery greatly strengthens the case for an origin in early solar-system irradiation, rather than external stellar seeding, for the shortest-lived radionuclides</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21336023','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21336023"><span id="translatedtitle">NEW TITANIUM ISOTOPE DATA FOR ALLENDE AND EFREMOVKA CAIs</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Leya, Ingo; Schoenbaechler, Maria; Kraehenbuehl, Urs; Halliday, Alex N.</p> <p>2009-09-10</p> <p>We measured the titanium (Ti) isotope composition, i.e., {sup 50}Ti/{sup 47}Ti, {sup 48}Ti/{sup 47}Ti, and {sup 46}Ti/{sup 47}Ti, in five calcium-rich-aluminum-rich refractory inclusions (CAIs) from the oxidized CV3 chondrite Allende and in two CAIs from the reduced CV3 chondrite Efremovka. Our data indicate that CAIs are enriched in {sup 50}Ti/{sup 47}Ti and {sup 46}Ti/{sup 47}Ti and are slightly depleted in {sup 48}Ti/{sup 47}Ti compared to normal Ti defined by ordinary chondrites, eucrites, ureilites, mesosiderites, Earth, Moon, and Mars. Some CAIs have an additional {sup 50}Ti excess of {approx}8{epsilon} relative to bulk carbonaceous chondrites, which are enriched in {sup 50}Ti by {approx}2{epsilon} relative to terrestrial values, leading to a total excess of {approx}10{epsilon}. This additional {sup 50}Ti excess is correlated with nucleosynthetic anomalies found in {sup 62}Ni and {sup 96}Zr, all indicating an origin from a neutron-rich stellar source. Bulk carbonaceous chondrites show a similar trend, however, the extent of the anomalies is either less than or similar to the smallest anomalies seen in CAIs. Mass balance calculations suggest that bulk Allende Ti possibly consists of a mixture of at least two Ti components, anomalous Ti located in CAIs and a normal component possibly for matrix and chondrules. This argues for a heterogeneous distribution of Ti isotopes in the solar system. The finding that anomalous Ti is concentrated in CAIs suggests that CAIs formed in a specific region of the solar system and were, after their formation, not homogeneously redistributed within the solar system. Combining the CAI data with improved model predictions for early solar system irradiation effects indicates that a local production scenario for the relatively short lived radionuclides can be excluded, because the production of, e.g., {sup 10}Be, {sup <span class="hlt">26</span>}<span class="hlt">Al</span>, and {sup <span class="hlt">41</span>}<span class="hlt">Ca</span>, would result in a significant collateral shift in Ti isotopes, which is not seen in the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFMEP32A..02C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFMEP32A..02C"><span id="translatedtitle">A Step Toward Physics-Based Cosmogenic Nuclide Production Rates: Measurements of High-Energy Neutron Cross Sections</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Caffee, M. W.; Welten, K. C.; Ninomiya, K.; Omoto, T.; Nakagaki, R.; Takahashi, N.; Kasamatsu, Y.; Shima, T.; Sekimoto, S.; Yashima, H.; Shibata, S.; Matsumura, H.; Bajo, K.; Nagao, K.; Satoh, D.; Iwamoto, Y.; Hagiwara, M.; Shinohara, A.; Imamura, M.; Nishiizumi, K.</p> <p>2010-12-01</p> <p>-lived nuclides were measured by low-level γ-ray counting [e.g., 2, 3]. After completion of these measurements, the long-lived nuclides were chemically isolated and measured using AMS. The noble gases were measured by high-sensitivity noble gas mass spectrometry. We will present high-energy neutron cross sections for 10Be, <span class="hlt">26</span><span class="hlt">Al</span>, <span class="hlt">36</span><span class="hlt">Cl</span>, and 21Ne from various target elements. [1] Imamura et al. (1990) NIM B52, 595-600. [2] Ninomiya et al. (2009) Radiochim. Acta [3] Sekimoto et al. (2010) J. Nucl. Sci. Technol.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22031277','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22031277"><span id="translatedtitle">Mass spectrometry with accelerators.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Litherland, A E; Zhao, X-L; Kieser, W E</p> <p>2011-01-01</p> <p>As one in a series of articles on Canadian contributions to mass spectrometry, this review begins with an outline of the history of accelerator mass spectrometry (AMS), noting roles played by researchers at three Canadian AMS laboratories. After a description of the unique features of AMS, three examples, (14)C, (10)Be, and (129)I are given to illustrate the methods. The capabilities of mass spectrometry have been extended by the addition of atomic isobar selection, molecular isobar attenuation, further ion acceleration, followed by ion detection and ion identification at essentially zero dark current or ion flux. This has been accomplished by exploiting the techniques and accelerators of atomic and nuclear physics. In 1939, the first principles of AMS were established using a cyclotron. In 1977 the selection of isobars in the ion source was established when it was shown that the (14)N(-) ion was very unstable, or extremely difficult to create, making a tandem electrostatic accelerator highly suitable for assisting the mass spectrometric measurement of the rare long-lived radioactive isotope (14)C in the environment. This observation, together with the large attenuation of the molecular isobars (13)CH(-) and (12)CH 2(-) during tandem acceleration and the observed very low background contamination from the ion source, was found to facilitate the mass spectrometry of (14)C to at least a level of (14)C/C ~ 6 × 10(-16), the equivalent of a radiocarbon age of 60,000 years. Tandem Accelerator Mass Spectrometry, or AMS, has now made possible the accurate radiocarbon dating of milligram-sized carbon samples by ion counting as well as dating and tracing with many other long-lived radioactive isotopes such as (10)Be, (<span class="hlt">26</span>)<span class="hlt">Al</span>, (<span class="hlt">36</span>)<span class="hlt">Cl</span>, and (129)I. The difficulty of obtaining large anion currents with low electron affinities and the difficulties of isobar separation, especially for the heavier mass ions, has prompted the use of molecular anions and the search for alternative</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMEP53A3627P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMEP53A3627P"><span id="translatedtitle">Glacial Erosion Rates from Bayesian Inversion of Cosmogenic Nuclide Concentrations in a Bedrock Core, Streaked Mtn., ME</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ploskey, Z. T.; Stone, J. O.</p> <p>2014-12-01</p> <p>Glacial erosion is an important source of sediment and could be an important coupling to glacier and ice sheet models that track sediment. However, glacial erosion is difficult to quantify, and models of glacial erosion can benefit from independent erosion rate estimates. Here we present the results of a Bayesian Markov chain Monte Carlo (MCMC) inversion of a cosmogenic nuclide (CN) geomorphic model for glacial erosion rates on a bedrock landform formerly eroded beneath the Laurentide ice sheet. The CN 10Be was measured in quartz to 8 m depth in a bedrock core from the summit of Streaked Mountain, ME. The accumulation of 10Be was modeled over multiple glacial cycles of alternating exposure and glacial erosion. This model was invertedfor glacial erosion rates and burial history using MCMC algorithms implemented in PyMC (Patil et al., 2010). This Bayesian approach allows us to incorporate prior constraints on ice cover history, including oxygen isotope records and radiometric dates, which is otherwise difficult to differentiate from erosion in rapidly eroding areas. We compare these results to depth profile and surface CN measurements elsewhere in Maine (Ploskey and Stone, 2013).The forward model of CN production used in the inversion is part of Cosmogenic (github.com/cosmolab/cosmogenic), an open-source Python-based software library we developed for modeling the growth and decay of in-situ CN inventories in rock during geomorphic evolution. It includes calibrated production rates for 10Be and <span class="hlt">26</span><span class="hlt">Al</span> in quartz and <span class="hlt">36</span><span class="hlt">Cl</span> in K-feldspar by both neutrons and muons, with more isotopic production pathways and material targets to be added in the future. Production rates are scaled to the site altitude and latitude using modular scaling schemes. Cosmogenic includes a variety of functions representing common geomorphic histories, and can be used to model any arbitrary exposure, erosion and burial history that can be defined as Python function.ReferencesPatil, A., D. Huard and C</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22356503','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22356503"><span id="translatedtitle">Observation of 23 supernovae that exploded <300 pc from Earth during the past 300 kyr</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Firestone, R. B.</p> <p>2014-07-01</p> <p>Four supernovae (SNe), exploding ≤300 pc from Earth, were recorded 44, 37, 32, and 22 kyr ago in the radiocarbon ({sup 14}C) record during the past 50 kyr. Each SN left a nearly identical signature in the record, beginning with an initial sudden increase in atmospheric radiocarbon, when the SN exploded, followed by a hiatus of 1500 yr, and concluding with a sustained 2000 yr increase in global radiocarbon due to γ-rays produced by diffusive shock in the SN remnant (SNR). For the past 18 kyr excess radiocarbon has decayed with the {sup 14}C half-life. SN22kyrBP, is identified as the Vela SN that exploded 250 ± 30 pc from Earth. These SN are confirmed in the {sup 10}Be, {sup <span class="hlt">26</span>}<span class="hlt">Al</span>, {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>, and NO{sub 3}{sup −} geologic records. The rate of near-Earth SNe is consistent with the observed rate of historical SNe giving a galactic rate of 14 ± 3 kyr{sup –1} assuming the Chandra Galactic Catalog SNR distribution. The Earth has been used as a calorimeter to determine that ≈2 × 10{sup 49} erg were released as γ-rays at the time of each SN explosion and ≈10{sup 50} erg in γ-rays following each SN. The background rate of {sup 14}C production by cosmic rays has been determined as 1.61 atoms cm{sup –2} s{sup –1}. Approximately 1/3 of the cosmic ray energy produced by diffusive shock in the SNR was observed to be emitted as high-energy γ-rays. Analysis of the {sup 10}Be/{sup 9}Be ratio in marine sediment identified 19 additional near-Earth SNe that exploded 50-300 kyr ago. Comparison of the radiocarbon record with global temperature variations indicated that each SN explosion is correlated with a concurrent global warming of ≈3°C-4°C.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/137513','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/137513"><span id="translatedtitle">The use of chlorine isotope measurements to trace water movements at Yucca Mountain</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Norris, A.E.</p> <p>1989-08-01</p> <p>The rates of water movements in the tuffs at Yucca Mountain are important for assessing the performance of a potential high-level nuclear waste repository. Measurements of cosmogenic 3.0 {times} 10{sup 5} yr {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> in tuff from the unsaturated zone and in water from the saturated zone can provide information about water movements over times of 10{sup 15} to 10{sup 6} years. The data derived from the analysis of cuttings from a dry-drilled hole at Yucca Mountain indicate the presence of a {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> background that must be taken into account for proper interpretation of the {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> interpretation of the {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> results. Similarly, the {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> measured in water from the saturated zone requires additional work for correct interpretation. Fallout of {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> from nuclear weapons tests between 1952 and 1962 provided a tracer for an infiltration study. Measurements of the {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> bomb pulse in tuffs from the unsaturated zone show potential for tracing recent water flow in faults and fractures. 5 refs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1995Metic..30R.559O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1995Metic..30R.559O"><span id="translatedtitle">The Chondrite Neagari: Petrography, Mineralogy, Chemical Compositions, and Cosmogenic Nuclides</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Okada, A.; Komura, K.; Nagao, K.; Nishiizumi, K.; Miyamoto, Y.; Sakamoto, K.; Ebihara, M.; Shima, M.</p> <p>1995-09-01</p> <p>) have been identified and their contents were determined by using a mock sample having known amounts of natural radioactivities. Among these nuclides, ^44mSc has the shortest half life (2.44 d) and has also been measured in the Mihonoseki meteorite [1]. Cosmogenic components were also observed for ^3He, ^21Ne, and ^38Ar by noble gas mass spectrometry. Cosmic-ray exposure ages calculated from cosmogenic ^21Ne and ^38Ar contents coupled with production rates by Eugster [2] and Schultz et al. [3], respectively, seem to be consistent (about 45 Ma), but the age from ^3He is significantly lower. Considering the loss of radiogenic ^4He, the Neagari meteorite must have experienced a high temperature event in space. Cosmogenic radionuclides ^10Be, ^<span class="hlt">26</span><span class="hlt">Al</span>, and ^<span class="hlt">36</span><span class="hlt">Cl</span> were also measured in an aliquot (77 mg) of the Neagari meteorite using an AMS facility at Lawrence Livermore National Laboratory. The concentrations of these nuclides in conjunction with the noble gas data as well as data of elemental abundances provide better knowledge of the exposure history of this meteorite. References: [1] Shima M. et al. (1993) LPS XXIV, 1297-1298. [2] Eugster O. (1988) GCA, 52, 1649-1662. [3] Schultz L. et al. (1991) GCA, 55, 59-66.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1083465','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1083465"><span id="translatedtitle">Diagnosis and assessment of skeletal related disease using calcium 41</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Hillegonds, Darren J.; Vogel, John S.; Fitzgerald, Robert L.; Deftos, Leonard J.; Herold, David; Burton, Douglas W.</p> <p>2013-03-05</p> <p>A method of determining calcium metabolism in a patient comprises the steps of administering radioactive calcium isotope .sup.<span class="hlt">41</span><span class="hlt">Ca</span> to the patient, allowing a period of time to elapse sufficient for dissemination and reaction of the radioactive calcium isotope .sup.<span class="hlt">41</span><span class="hlt">Ca</span> by the patient, obtaining a sample of the radioactive calcium isotope .sup.<span class="hlt">41</span><span class="hlt">Ca</span> from the patient, isolating the calcium content of the sample in a form suitable for precise measurement of isotopic calcium concentrations, and measuring the calcium content to determine parameters of calcium metabolism in the patient.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1042648','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1042648"><span id="translatedtitle">Diagnosis and assessment of skeletal related disease using calcium 41</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Hillegonds, Darren J.; Vogel, John S.; Fitzgerald, Robert L.; Deftos, Leonard J.; Herold, David; Burton, Douglas W.</p> <p>2012-05-15</p> <p>A method of determining calcium metabolism in a patient comprises the steps of administering radioactive calcium isotope .sup.<span class="hlt">41</span><span class="hlt">Ca</span> to the patient, allowing a period of time to elapse sufficient for dissemination and reaction of the radioactive calcium isotope .sup.<span class="hlt">41</span><span class="hlt">Ca</span> by the patient, obtaining a sample of the radioactive calcium isotope .sup.<span class="hlt">41</span><span class="hlt">Ca</span> from the patient, isolating the calcium content of the sample in a form suitable for precise measurement of isotopic calcium concentrations, and measuring the calcium content to determine parameters of calcium metabolism in the patient.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6965325','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6965325"><span id="translatedtitle">Studies towards a method for radiocalcium dating of bones</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kutschera, W.; Ahmad, I.; Billquist, P.J. . Physics Dept.)</p> <p>1989-01-01</p> <p>The authors made preliminary AMS measurements of [sup <span class="hlt">41</span>]<span class="hlt">Ca</span>/Ca ratios in bone and limestone specimens with the Argonne Tandem-Linac Accelerator System (ATLAS). They were able to avoid pre-enrichment of [sup <span class="hlt">41</span>]<span class="hlt">Ca</span> used in previous experiments due to a substantial increase in Ca-beam intensity. Most of the measured ratios lie in the 10[sup [minus]14] range, with a few values below 10[sup [minus]14]. In general, these values are higher than the ones observed by the AMS group at the University of Pennsylvania. They discuss possible implications of these results. They also present the current status of half-life measurements of [sup <span class="hlt">41</span>]<span class="hlt">Ca</span> and discuss [sup <span class="hlt">41</span>]<span class="hlt">Ca</span> production processes on earth.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_16 --> <div id="page_17" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="321"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/24144617','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/24144617"><span id="translatedtitle">Accurate determination of ⁴¹Ca concentrations in spent resins from the nuclear industry by accelerator mass spectrometry.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nottoli, Emmanuelle; Bourlès, Didier; Bienvenu, Philippe; Labet, Alexandre; Arnold, Maurice; Bertaux, Maité</p> <p>2013-12-01</p> <p>The radiological characterisation of nuclear waste is essential for managing storage sites. Determining the concentration of Long-Lived RadioNuclides (LLRN) is fundamental for their long-term management. This paper focuses on the measurement of low (<span class="hlt">41</span>)<span class="hlt">Ca</span> concentrations in ions exchange resins used for primary fluid purification in Pressurised Water Reactors (PWR). (<span class="hlt">41</span>)<span class="hlt">Ca</span> concentrations were successfully measured by Accelerator Mass Spectrometry (AMS) after the acid digestion of resin samples, followed by radioactive decontamination and isobaric suppression through successive hydroxide, carbonate, nitrate and final CaF2 precipitations. Measured (<span class="hlt">41</span>)<span class="hlt">Ca</span> concentrations ranged from 0.02 to 0.03 ng/g, i.e. from 0.06 to 0.09 Bq/g. The (<span class="hlt">41</span>)<span class="hlt">Ca</span>/(60)Co activity ratios obtained were remarkably reproducible and in good agreement with the current ratio used for resins management. PMID:24144617</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/9227999','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/9227999"><span id="translatedtitle">Chlorine-36 in fossil rat urine: an archive of cosmogenic nuclide deposition during the past 40,000 years.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Plummer, M A; Phillips, F M; Fabryka-Martin, J; Turin, H J; Wigand, P E; Sharma, P</p> <p>1997-07-25</p> <p>Knowledge of the production history of cosmogenic nuclides, which is needed for geological and archaeological dating, has been uncertain. Measurements of chlorine-36/chlorine (<span class="hlt">36</span><span class="hlt">Cl</span>/Cl) ratios in fossil packrat middens from Nevada that are radiocarbon-dated between about 38 thousand years ago (ka) and the present showed that <span class="hlt">36</span><span class="hlt">Cl</span>/Cl ratios were higher by a factor of about 2 before approximately 11 ka. This raises the possibility that cosmogenic production rates just before the close of the Pleistocene were up to 50% higher than is suggested by carbon-14 calibration data. The discrepancy could be explained by addition of low-carbon-14 carbon dioxide to the atmosphere during that period, which would have depressed atmospheric radiocarbon activity. Alternatively, climatic effects on <span class="hlt">36</span><span class="hlt">Cl</span> deposition may have enhanced the <span class="hlt">36</span><span class="hlt">Cl</span>/Cl ratios.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/569385','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/569385"><span id="translatedtitle">Chlorine-36 in fossil rat urine: An archive of cosmogenic nuclide deposition during the past 40,000 years</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Plummer, M.A.; Phillips, F.M.; Fabryka-Martin, J.</p> <p>1997-07-25</p> <p>Knowledge of the production history of cosmogenic nuclides, which is needed for geological and archaeological dating, has been uncertain. Measurements of chlorine-36/chlorine ({sup <span class="hlt">36</span>}<span class="hlt">Cl</span>/Cl) ratios in fossil packrat middens from Nevada that are radiocarbon-dated between about 38 thousand years ago (ka) and the present showed that {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>/Cl ratios were higher by a factor of about 2 before {approx} 11 ka. This raises the possibility that cosmogenic production rates just before the close of the Pleistocene were up to 50% higher than is suggested by carbon-14 calibration data. The discrepancy could be explained by addition of low-carbon-14 carbon dioxide to the atmosphere during that period, which would have depressed atmospheric radiocarbon activity. Alternatively, climatic effects on {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> deposition may have enhanced the {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>/Cl ratios. 49 refs., 3 figs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5858007','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5858007"><span id="translatedtitle">Relative efficacies of 1,4-diazepines on GABA-stimulated chloride influx in rat brain vesicles</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Ikeda, Masaaki; Weber, K.H.; Bechtel, W.D.; Malatynska, E.; Yamamura, H.I.</p> <p>1989-01-01</p> <p>The effects of 1,4-diazepines with two annelated heterocycles (brotizolam (WE 941), ciclotizolam (WE 973) and WE 1008) on gamma-aminobutyric acid (GABA)-stimulated chloride influx into rat brain membrane vesicles were examined. Brotizolam enhanced GABA-stimulated /sup <span class="hlt">36</span>/<span class="hlt">Cl</span>/sup /minus// influx, while ciclotizolam and WE 1008 showed only a small enhancement of GABA-stimulated /sup <span class="hlt">36</span>/<span class="hlt">Cl</span>/sup /minus// uptake. Brotizolam resulted in a left shift of the GABA dose response curve at lower concentrations of GABA, while at higher concentrations of GABA, brotizolam caused a reduction of the maximal response. The enhancement of GABA-stimulated /sup <span class="hlt">36</span>/<span class="hlt">Cl</span>/sup /minus// uptake by brotizolam was antagonized by Ro 15-1788. At higher concentration of GABA (300 /mu/M), brotizolam inhibited GABA-stimulated /sup <span class="hlt">36</span>/<span class="hlt">Cl</span>/sup /minus// uptake in a dose dependent manner and Ro 15-1788 failed to antagonize this effect.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002HydJ...11..217D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002HydJ...11..217D"><span id="translatedtitle">Chlorine-36 in groundwater of the United States: empirical data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Davis, Stanley; Moysey, Stephen; Cecil, DeWayne; Zreda, Marek</p> <p>2002-11-01</p> <p>Natural production of the radionuclide chlorine-36 (<span class="hlt">36</span><span class="hlt">Cl</span>) has provided a valuable tracer for groundwater studies. The nuclear industry, especially the testing of thermonuclear weapons, has also produced large amounts of <span class="hlt">36</span><span class="hlt">Cl</span> that can be detected in many samples of groundwater. In order to be most useful in hydrologic studies, the natural production prior to 1952 should be distinguished from more recent artificial sources. The object of this study was to reconstruct the probable preanthropogenic levels of <span class="hlt">36</span><span class="hlt">Cl</span> in groundwater in the United States. Although significant local variations exist, they are superimposed on a broad regional pattern of <span class="hlt">36</span><span class="hlt">Cl</span>/Cl ratios in the United States. Owing to the influence of atmospherically transported ocean salt, natural ratios of <span class="hlt">36</span><span class="hlt">Cl</span>/total Cl are lowest near the coast and increase to a maximum in the central Rocky Mountains of the United States. Résumé. La production naturelle du radionucléide chlore-36 (<span class="hlt">36</span><span class="hlt">Cl</span>) fournit un intéressant traceur pour l'étude des eaux souterraines. L'industrie nucléaire, en particulier les essais de bombes thermonucléaires, a également produit de grandes quantités de <span class="hlt">36</span><span class="hlt">Cl</span> qui a pu être détecté dans de nombreux échantillons d'eau souterraine. Afin d'en améliorer l'usage dans les études hydrologiques, la production naturelle avant 1952 doit être distinguée des sources artificielles plus récentes. L'objectif de cette étude a été la reconstruction des niveaux probables de <span class="hlt">36</span><span class="hlt">Cl</span> dans les eaux souterraines des États-Unis, avant la production anthropique du <span class="hlt">36</span><span class="hlt">Cl</span>. Bien qu'il existe des variations locales significatives, elles se surimposent à un canevas régional de rapports <span class="hlt">36</span><span class="hlt">Cl</span>/Cl dans les États-Unis. Du fait de l'influence du sel océanique transporté dans l'atmosphère, les rapports naturels de <span class="hlt">36</span><span class="hlt">Cl</span>/Cl total sont plus faibles près de la côte et augmentent jusqu'à un maximum dans les Montagnes Rocheuses centrales des États-Unis. Resumen. La producción natural del radionucleido cloro</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20040065906&hterms=inclusion&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dinclusion','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20040065906&hterms=inclusion&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dinclusion"><span id="translatedtitle">Evidence for Live Cl-36 in Ca-Al-rich Inclusions from the Ningqiang Carbonaceous Chondrite</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lin, Y.; Guan, Y.; Leshin, L. A.; Ouyang, Z.; Wang, D.</p> <p>2004-01-01</p> <p>The short-lived radionuclide Cl-36 decays to either Ar-36 (98.1%, beta(sup -)) or S-36 (1.9%, epsilon and beta(sup +)), with a half life of 3.01 x 10(exp 5) yr. Both the nucleosynthetic and spallation models suggest high initial Cl-<span class="hlt">36</span>/<span class="hlt">Cl</span>-35 ratios ((Cl-<span class="hlt">36</span>/<span class="hlt">Cl</span>-35)o up to approximately 10(exp -4)) in the early solar system. Previous observed excess Ar-36 in Efremovka matrix has been interpreted to represent a much lower (Cl-<span class="hlt">36</span>/<span class="hlt">Cl</span>-35)o ratio of approximately 1 x 10(exp -6). From the observed S-36 excesses in sodalite in calcium aluminum-rich inclusions (CAIs), we report in this study the first direct evidence of the presence of Cl-36 in primitive meteorites. The inferred (Cl-<span class="hlt">36</span>/<span class="hlt">Cl</span>-35)o ratios range from approximately 5 x 10(exp -6) to approximately 1 x 10(exp -5).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/894191','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/894191"><span id="translatedtitle">Chlorine-36 alidation Study at Yucca Mountain, Nevada</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>J. Paces</p> <p>2006-08-28</p> <p>The amount, spatial distribution, and velocity of water percolating through the unsaturated zone (UZ) at Yucca Mountain, Nevada, are important issues for assessing the performance of the proposed deep geologic repository for spent nuclear fuel and high-level radioactive waste. To help characterize the nature and history of UZ flow, isotopic studies were initiated in 1995, using rock samples collected from the Miocene ash-flow tuffs in the Exploratory Studies Facility (ESF), an 8-km-long tunnel constructed along the north-south extent of the repository block, and the Enhanced Characterization of the Repository Block (ECRB) Cross Drift, a 2.5-km-long tunnel constructed across the repository block (Figure 1-1, Sources: Modified from DOE 2002 [Figure 1-14] and USBR 1996). Scientists from Los Alamos National Laboratory (LANL) analyzed for chlorine-36 ({sup <span class="hlt">36</span>}<span class="hlt">Cl</span>) in salts leached from whole-rock samples collected from tunnel walls and subsurface boreholes, and scientists from the U.S. Geological Survey (USGS) analyzed for isotopes of oxygen, carbon, uranium, lead, thorium, and strontium in secondary minerals collected from subsurface fractures and lithophysal cavities. Elevated values for ratios of {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> to total chloride ({sup <span class="hlt">36</span>}<span class="hlt">Cl</span>/CL) at the level of the proposed repository indicated that small amounts of water carrying bomb-pulse {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> (i.e., {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>/Cl ratios greater than 1250 x 10{sup -15} resulting from {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> produced by atmospheric testing of nuclear devices during the 1950s and early 1960s) had percolated through welded and nonwelded tuffs to depths of 200 to 300 meters (m) beneath the land surface over the past 50 years. Because of the implications of short travel times to the performance of the proposed repository, the U.S. Department of Energy (DOE)/Office of Civilian Radioactive Waste Management (OCRWM), Office of Repository Development (ORD), decided to verify the {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>/Cl data with an independent validation study. DOE asked the USGS</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70022217','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70022217"><span id="translatedtitle">Chlorine-36 and cesium-137 in ice-core samples from mid-latitude glacial sites in the Northern Hemisphere</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Green, J.R.; Cecil, L.D.; Synal, H.-A.; Kreutz, K.J.; Wake, C.P.; Naftz, D.L.; Frape, S.K.</p> <p>2000-01-01</p> <p>Chlorine-36 (<span class="hlt">36</span><span class="hlt">Cl</span>) concentrations, <span class="hlt">36</span><span class="hlt">Cl</span>/Cl ratios, and <span class="hlt">36</span><span class="hlt">Cl</span> fluxes in ice-core samples collected from the Upper Fremont Glacier (UFG) in the Wind River Mountain Range, Wyoming, United States and the Nangpai Gosum Glacier (NGG) in the Himalayan Mountains, Nepal, were determined and compared with published results from the Dye-3 ice-core drilling site on the Greenland Ice Sheet. Cesium-137 (137Cs) concentrations in the NGG also were determined. The background fluxes for <span class="hlt">36</span><span class="hlt">Cl</span> for each glacial site were similar: (1.6??0.3)??10-2 atoms/cm2 s for the UFG samples, (0.7??0.1)??10-2 atoms/cm2 s for the NGG samples, and (0.4??0.1)??10-2 atoms/cm2 s for the Dye-3 samples. The <span class="hlt">36</span><span class="hlt">Cl</span> fluxes in ice that was deposited as snow during peak atmospheric nuclear weapon test (1957-1958) were (33??1)??10-2 atoms/cm2 s for the UFG site, (291??3)??10-2 atoms/cm2 s for the NGG site, and (124??5)??10-2 atoms/ cm2 s for the Dye-3 site. A weapon test period 137Cs concentration of 0.79??0.05 Bq/kg in the NGG ice core also was detected in the same section of ice that contained the largest <span class="hlt">36</span><span class="hlt">Cl</span> concentration. ?? 2000 Elsevier Science B.V. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5403593','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5403593"><span id="translatedtitle">Modulation of GABA-stimulated chloride influx into membrane vesicles from rat cerebral cortex by triazolobenzodiazepines</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Obata, T.; Yamamura, H.I.</p> <p>1988-01-01</p> <p>The effects of triazolobenzodiazepines of GABA-stimulated /sup <span class="hlt">36</span>/<span class="hlt">Cl</span>/sup -/ uptake by membrane vesicles from rat cerebral cortex were examined. Triazolam and alprazolam showed a significant enhancement of GABA-stimulated /sup <span class="hlt">36</span>/<span class="hlt">Cl</span>/sup -/ uptake at 0.01-10 uM. On the other hand, adinazolam showed a small enhancement at 0.1-1 uM followed by a significant inhibition of GABA-stimulated /sup <span class="hlt">36</span>/<span class="hlt">Cl</span>/sup -/ uptake at 100 uM. The enhancement of GABA-stimulated /sup <span class="hlt">36</span>/<span class="hlt">Cl</span>/sup -/ uptake by 1 uM alprazolam was antagonized by Ro15-1788, a benzodiazepine antagonist, but the inhibition of this response by 30 uM adinazolam was not antagonized by Ro15-1788. These results indicate that triazolobenzodiazepines enhanced GABA-stimulated /sup <span class="hlt">36</span>/<span class="hlt">Cl</span>/sup -/ uptake through benzodiazepine receptors. High concentrations of adinazolam inhibit GABA-stimulated /sup <span class="hlt">36</span>/<span class="hlt">Cl</span>/sup -/ uptake which may be due to the direct blockade of GABA-gated chloride channel. 23 references, 4 figures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/19806723','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/19806723"><span id="translatedtitle">Chlorine-36 as a tracer of perchlorate origin.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sturchio, Neil C; Caffee, Marc; Beloso, Abelardo D; Heraty, Linnea J; Böhlke, John Karl; Hatzinger, Paul B; Jackson, W Andrew; Gu, Baohua; Heikoop, Jeffrey M; Dale, Michael</p> <p>2009-09-15</p> <p>Perchlorate (ClO4(-)) is ubiquitous in the environment. It is produced naturally by atmospheric photochemical reactions, and also is synthesized in large quantities for military, aerospace, and industrial applications. Nitrate-enriched salt deposits of the Atacama Desert (Chile) contain high concentrations of natural ClO4(-), and have been exported worldwide since the mid-1800s for use in agriculture. The widespread introduction of synthetic and agricultural ClO4(-) into the environment has contaminated numerous municipal water supplies. Stable isotope ratio measurements of Cl and O have been applied for discrimination of different ClO4(-) sources in the environment. This study explores the potential of <span class="hlt">36</span><span class="hlt">Cl</span> measurements for further improving the discrimination of ClO4(-) sources. Groundwater and desert soil samples from the southwestern United States (U.S.) contain ClO4(-) having high <span class="hlt">36</span><span class="hlt">Cl</span> abundances (<span class="hlt">36</span><span class="hlt">Cl</span>/Cl = 3100 x 10(-15) to 28,800 x 10(-15)), compared with those from the Atacama Desert (<span class="hlt">36</span><span class="hlt">Cl</span>/Cl = 0.9 x 10(-15) to 590 x 10(-15)) and synthetic ClO4(-) reagents and products (<span class="hlt">36</span><span class="hlt">Cl</span>/Cl = 0.0 x 10(-15) to 40 x 10(-15)). In conjunction with stable Cl and O isotope ratios, <span class="hlt">36</span><span class="hlt">Cl</span> data provide a clear distinction among three principal ClO4(-) source types in the environment of the southwestern U.S. PMID:19806723</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70036777','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70036777"><span id="translatedtitle">Chlorine-36 as a tracer of perchlorate origin</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Sturchio, N.C.; Caffee, M.; Beloso, A.D.; Heraty, L.J.; Böhlke, J.K.; Hatzinger, P.B.; Jackson, W.A.; Gu, B.; Heikoop, J.M.; Dale, M.</p> <p>2009-01-01</p> <p>Perchlorate (ClO4-) is ubiquitous in the environment. It is produced naturally by atmospheric photochemical reactions, and also is synthesized in large quantities for military, aerospace, and industrial applications. Nitrate-enriched salt deposits of the Atacama Desert (Chile) contain high concentrations of natural ClO4-, and have been exported worldwide since the mid-1800s for use in agriculture. The widespread introduction of synthetic and agricultural ClO4- into the environment has contaminated numerous municipal water supplies. Stable isotope ratio measurements of Cl and O have been applied for discrimination of different ClO4- sources in the environment. This study explores the potential of <span class="hlt">36</span><span class="hlt">Cl</span> measurements for further improving the discrimination of ClO4- sources. Groundwater and desert soil samples from the southwestern United States (U.S.) contain ClO4- having high <span class="hlt">36</span><span class="hlt">Cl</span> abundances (<span class="hlt">36</span><span class="hlt">Cl</span>/Cl = 3100 ?? 10-15 to 28,800 ?? 10 -15), compared with those from the Atacama Desert (<span class="hlt">36</span><span class="hlt">Cl</span>/Cl = 0.9 ?? 10-15 to 590 ?? 10-15) and synthetic ClO4- reagents and products (<span class="hlt">36</span><span class="hlt">Cl</span>/Cl = 0.0 ?? 10-15 to 40 ?? 1015). In conjunction with stable Cl and O isotope ratios, <span class="hlt">36</span><span class="hlt">Cl</span> data provide a clear distinction among three principal. ClO4- source types in the environment of the southwestern U.S. ?? 2009 American Chemical Society.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/765561','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/765561"><span id="translatedtitle">Chlorine-36 in Water, Snow, and Mid-Latitude Glacial Ice of North America: Meteoric and Weapons-Tests Production in the Vicinity of the Idaho National Engineering and Environmental Laboratory, Idaho</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>L. DeWayne; J. R. Green; S. Vogt, P. Sharma; S. K. Frape; S. N. Davis; G. L. Cottrell</p> <p>1999-01-01</p> <p>Measurements of chlorine-36 (<span class="hlt">36</span><span class="hlt">Cl</span>) were made for 64 water, snow, and glacial-ice and -runoff samples to determine the meteoric and weapons-tests-produced concentrations and fluxes of this radionuclide at mid-latitudes in North America. The results will facilitate the use of <span class="hlt">36</span><span class="hlt">Cl</span> as a hydrogeologic tracer at the Idaho National Engineering and Environmental Laboratory (INEEL). This information was used to estimate meteoric and weapons-tests contributions of this nuclide to environmental inventories at and near the INEEL. The data presented in this report suggest a meteoric source <span class="hlt">36</span><span class="hlt">Cl</span> for environmental samples collected in southeastern Idaho and western Wyoming if the concentration is less than 1 x 10 7 atoms/L. Additionally, concentrations in water, snow, or glacial ice between 1 x 10 7 and 1 x 10 8 atoms/L may be indicative of a weapons-tests component from peak <span class="hlt">36</span><span class="hlt">Cl</span> production in the late 1950s. Chlorine-36 concentrations between 1 x 10 8 and 1 x 10 9 atoms/L may be representative of re-suspension of weapons-tests fallout airborne disposal of <span class="hlt">36</span><span class="hlt">Cl</span> from the INTEC, or evapotranspiration. It was concluded from the water, snow, and glacial data presented here that concentrations of <span class="hlt">36</span><span class="hlt">Cl</span> measured in environmental samples at the INEEL larger than 1 x 10 9 atoms/L can be attributed to waste-disposal practices.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1998HydJ....6..104D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1998HydJ....6..104D"><span id="translatedtitle">Chlorine-36 and the initial value problem</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Davis, Stanley N.; Cecil, DeWayne; Zreda, Marek; Sharma, Pankaj</p> <p></p> <p>Chlorine-36 is a radionuclide with a half-life of 3.01×105a. Most <span class="hlt">36</span><span class="hlt">Cl</span> in the hydrosphere originates from cosmic radiation interacting with atmospheric gases. Large amounts were also produced by testing thermonuclear devices during 1952-58. Because the monovalent anion, chloride, is the most common form of chlorine found in the hydrosphere and because it is extremely mobile in aqueous systems, analyses of both total Cl- as well as <span class="hlt">36</span><span class="hlt">Cl</span> have been important in numerous hydrologic studies. In almost all applications of <span class="hlt">36</span><span class="hlt">Cl</span>, a knowledge of the initial, or pre-anthropogenic, levels of <span class="hlt">36</span><span class="hlt">Cl</span> is useful, as well as essential in some cases. Standard approaches to the determination of initial values have been to: (a) calculate the theoretical cosmogenic production and fallout, which varies according to latitude; (b) measure <span class="hlt">36</span><span class="hlt">Cl</span> in present-day precipitation and assume that anthropogenic components can be neglected; (c) assume that shallow groundwater retains a record of the initial concentration; (d) extract <span class="hlt">36</span><span class="hlt">Cl</span> from vertical depth profiles in desert soils; (e) recover <span class="hlt">36</span><span class="hlt">Cl</span> from cores of glacial ice; and (f) calculate subsurface production of <span class="hlt">36</span><span class="hlt">Cl</span> for water that has been isolated from the atmosphere for more than one million years. The initial value from soil profiles and ice cores is taken as the value that occurs directly below the depth of the easily defined bomb peak. All six methods have serious weaknesses. Complicating factors include <span class="hlt">36</span><span class="hlt">Cl</span> concentrations not related to cosmogenic sources, changes in cosmogenic production with time, mixed sources of chloride in groundwater, melting and refreezing of water in glaciers, and seasonal groundwater recharge that does not contain average year-long concentrations of <span class="hlt">36</span><span class="hlt">Cl</span>. Résumé Le chlore-36 est un radionucléide de période 3.01×105a. Pour l'essentiel, le <span class="hlt">36</span><span class="hlt">Cl</span> dans l'hydrosphère provient des effets du rayonnement cosmique sur les gaz atmosphériques. De grandes quantités de <span class="hlt">36</span><span class="hlt">Cl</span> ont aussi été produites au cours des</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70026911','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70026911"><span id="translatedtitle">A high resolution record of chlorine-36 nuclear-weapons-tests fallout from Central Asia</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Green, J.R.; Cecil, L.D.; Synal, H.-A.; Santos, J.; Kreutz, K.J.; Wake, C.P.</p> <p>2004-01-01</p> <p>The Inilchek Glacier, located in the Tien Shan Mountains, central Asia, is unique among mid-latitude glaciers because of its relatively large average annual accumulation. In July 2000, two ice cores of 162 and 167 meters (m) in length were collected from the Inilchek Glacier for (chlorine-36) <span class="hlt">36</span><span class="hlt">Cl</span> analysis a part of a collaborative international effort to study the environmental changes archived in mid-latitude glaciers worldwide. The average annual precipitation at the collection site was calculated to be 1.6 m. In contrast, the reported average annual accumulations at the high-latitude Dye-3 glacial site, Greenland, the mid-latitude Guliya Ice Cap, China, and the mid-latitude Upper Fremont Glacier, Wyoming, USA, were 0.52, 0.16 and 0.76 m, respectively. The resolution of the <span class="hlt">36</span><span class="hlt">Cl</span> record in one of the Inilchek ice cores was from 2 to 10 times higher than the resolution of the records at these other sites and could provide an opportunity for detailed study of environmental changes that have occurred over the past 150 years. Despite the differences in accumulation among these various glacial sites, the <span class="hlt">36</span><span class="hlt">Cl</span> profile and peak concentrations for the Inilchek ice core were remarkably similar in shape and magnitude to those for ice cores from these other sites. The <span class="hlt">36</span><span class="hlt">Cl</span> peak concentration from 1958, the year during the mid-1900s nuclear-weapons-tests period when <span class="hlt">36</span><span class="hlt">Cl</span> fallout was largest, was preserved in the Inilchek core at a depth of 90.56 m below the surface of the glacier (74.14-m-depth water equivalent) at a concentration of 7.7 ?? 105 atoms of <span class="hlt">36</span><span class="hlt">Cl</span>/gram (g) of ice. Peak <span class="hlt">36</span><span class="hlt">Cl</span> concentrations from Dye-3, Guliya and the Upper Fremont glacial sites were 7.1 ?? 105, 5.4 ?? 105 and 0.7 ?? 105 atoms of <span class="hlt">36</span><span class="hlt">Cl</span>/g of ice, respectively. Measurements of <span class="hlt">36</span><span class="hlt">Cl</span> preserved in ice cores improve estimates of historical worldwide atmospheric deposition of this isotope and allow the sources of <span class="hlt">36</span><span class="hlt">Cl</span> in ground water to be better identified. ?? 2004 Published by Elsevier B.V.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1998HydJ....6..104D&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1998HydJ....6..104D&link_type=ABSTRACT"><span id="translatedtitle">Chlorine-36 and the initial value problem</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Davis, Stanley N.; Cecil, DeWayne; Zreda, Marek; Sharma, Pankaj</p> <p></p> <p>Chlorine-36 is a radionuclide with a half-life of 3.01×105a. Most <span class="hlt">36</span><span class="hlt">Cl</span> in the hydrosphere originates from cosmic radiation interacting with atmospheric gases. Large amounts were also produced by testing thermonuclear devices during 1952-58. Because the monovalent anion, chloride, is the most common form of chlorine found in the hydrosphere and because it is extremely mobile in aqueous systems, analyses of both total Cl- as well as <span class="hlt">36</span><span class="hlt">Cl</span> have been important in numerous hydrologic studies. In almost all applications of <span class="hlt">36</span><span class="hlt">Cl</span>, a knowledge of the initial, or pre-anthropogenic, levels of <span class="hlt">36</span><span class="hlt">Cl</span> is useful, as well as essential in some cases. Standard approaches to the determination of initial values have been to: (a) calculate the theoretical cosmogenic production and fallout, which varies according to latitude; (b) measure <span class="hlt">36</span><span class="hlt">Cl</span> in present-day precipitation and assume that anthropogenic components can be neglected; (c) assume that shallow groundwater retains a record of the initial concentration; (d) extract <span class="hlt">36</span><span class="hlt">Cl</span> from vertical depth profiles in desert soils; (e) recover <span class="hlt">36</span><span class="hlt">Cl</span> from cores of glacial ice; and (f) calculate subsurface production of <span class="hlt">36</span><span class="hlt">Cl</span> for water that has been isolated from the atmosphere for more than one million years. The initial value from soil profiles and ice cores is taken as the value that occurs directly below the depth of the easily defined bomb peak. All six methods have serious weaknesses. Complicating factors include <span class="hlt">36</span><span class="hlt">Cl</span> concentrations not related to cosmogenic sources, changes in cosmogenic production with time, mixed sources of chloride in groundwater, melting and refreezing of water in glaciers, and seasonal groundwater recharge that does not contain average year-long concentrations of <span class="hlt">36</span><span class="hlt">Cl</span>. Résumé Le chlore-36 est un radionucléide de période 3.01×105a. Pour l'essentiel, le <span class="hlt">36</span><span class="hlt">Cl</span> dans l'hydrosphère provient des effets du rayonnement cosmique sur les gaz atmosphériques. De grandes quantités de <span class="hlt">36</span><span class="hlt">Cl</span> ont aussi été produites au cours des</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70022085','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70022085"><span id="translatedtitle">Use of chlorine-36 to determine regional-scale aquifer dispersivity, eastern Snake River Plain aquifer, Idaho/USA</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Cecil, L.D.; Welhan, J.A.; Green, J.R.; Grape, S.K.; Sudicky, E.R.</p> <p>2000-01-01</p> <p>Chlorine-36 (<span class="hlt">36</span><span class="hlt">Cl</span>) derived from processed nuclear waste that was disposed at the US Department of Energy's Idaho National Engineering and Environmental Laboratory (INEEL) through a deep injection well in 1958, was detected 24-28 yr later in groundwater monitoring wells approximately 26 km downgradient from the source. Groundwater samples covering the period 1966-1995 were selected from the US Geological Survey's archived-sample library at the INEEL and analyzed for <span class="hlt">36</span><span class="hlt">Cl</span> by accelerator mass spectrometry (AMS). The smaller <span class="hlt">36</span><span class="hlt">Cl</span> peak concentrations in water from the far-field monitoring wells relative to the input suggest that aquifer dispersivity may be large. However, the sharpness of the 1958 disposal peak of <span class="hlt">36</span><span class="hlt">Cl</span> is matched by the measured <span class="hlt">36</span><span class="hlt">Cl</span> concentrations in water from these wells. This implies that a small aquifer dispersivity may be attributed to preferential groundwater flowpaths. Assuming that tracer arrival times at monitoring wells are controlled by preferential flow, a 1-D system-response model was used to estimate dispersivity by comparing the shape of predicted <span class="hlt">36</span><span class="hlt">Cl</span>-concentration curves to the shape of <span class="hlt">36</span><span class="hlt">Cl</span>-concentration curves measured in water from these observation wells. The comparisons suggest that a 1-D dispersivity of 5 m provides the best fit to the tracer data. Previous work using a 2-D equivalent porous-media model concluded that longitudinal dispersivity (equivalent to 1-D dispersivity in our model) was 90 m (Ackerman, 1991). A 90 m dispersivity value eliminates the 1958 disposal peak in our model output curves. The implications of the arrival of <span class="hlt">36</span><span class="hlt">Cl</span> at downgradient monitoring wells are important for three reasons: (1) the arrival times and associated <span class="hlt">36</span><span class="hlt">Cl</span> concentrations provide quantitative constraints on residence times, velocities, and dispersivities in the aquifer; (2) they help to refine our working hypotheses of groundwater flow in this aquifer and (3) they may suggest a means of estimating the distribution of preferential flowpaths</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70019990','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70019990"><span id="translatedtitle">Identification of bomb-produced chlorine-36 in mid-latitude glacial ice of North America</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>DeWayne, Cecil L.; Vogt, S.</p> <p>1997-01-01</p> <p>In 1991, the U.S. Geological Survey collected a 160-meter (m) ice core from the Upper Fremont Glacier (43??07???N, 109??36???W) in the Wind River Mountain Range of Wyoming in the western United States [1]. In 1994-95, ice from this core was processed at the National Ice Core Laboratory in Denver, Colorado, and analyzed for chlorine-36 (<span class="hlt">36</span><span class="hlt">Cl</span>) by accelerator mass spectrometry at PRIME Laboratory, Purdue University. A tritium bomb peak identified in the work by [1] was used as a marker to estimate the depth of bomb-produced <span class="hlt">36</span><span class="hlt">Cl</span>. Tritium concentrations ranged from 0 tritium units (TU) for older ice to more than 300 TU at 29 m below the surface of the glacier, a depth that includes ice that was deposited as snow during nuclear-weapons tests through the early 1960's. Maximum <span class="hlt">36</span><span class="hlt">Cl</span> production during nuclear-weapons tests was in the late 1950's; therefore, the analyses were performed on ice from a depth of 29.8 to 32 m. Calculated flux for <span class="hlt">36</span><span class="hlt">Cl</span> in ice deposited in the late 1950's ranged from 1.2 ?? 0.1 ?? 10-1 atoms/cm2 s for ice from 29.8 to 30.4 m, to 2.9 ?? 0.1 ?? 10-1 atoms/cm2 s for ice from 31.5 to 32.0 m. Ice samples from a depth of 104.7 to 106.3 m were selected to represent pre-weapons tests <span class="hlt">36</span><span class="hlt">Cl</span> flux. Calculated flux for <span class="hlt">36</span><span class="hlt">Cl</span> in this deeper ice was 4.6 ?? 0.8 ?? 10-3 atoms/cm2 s for ice from 104.7 to 105.5 m and 2.0 ?? 0.2 ?? 10-2 atoms/cm2 s for ice from 105.5 to 106.3 m. These flux calculations from the Upper Fremont Glacier analyses are the first for bomb-produced <span class="hlt">36</span><span class="hlt">Cl</span> in ice from a mid-latitude glacier in North America. It may now be possible to fully quantify the flux of <span class="hlt">36</span><span class="hlt">Cl</span> from nuclear-weapons tests archived in mid-latitude glacial ice and to gain a better understanding of the distribution of <span class="hlt">36</span><span class="hlt">Cl</span> and other cosmogenic nuclides.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70027750','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70027750"><span id="translatedtitle">The probable importance of snow and sediment shielding on cosmogenic ages of north-central Colorado Pinedale and pre-Pinedale moraines</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Benson, L.; Madole, R.; Phillips, W.; Landis, G.; Thomas, T.; Kubik, P.</p> <p>2004-01-01</p> <p>Eight uncorrected <span class="hlt">36</span><span class="hlt">Cl</span> ages for Pinedale boulders in north-central Colorado fall in the range 16.5 to 20.9 kyr. 10Be age determinations on four of five boulders are in close agreement (???6% difference) with <span class="hlt">36</span><span class="hlt">Cl</span> determinations. Hypothetical corrections for snow shielding increased the <span class="hlt">36</span><span class="hlt">Cl</span> ages of Pinedale boulder surfaces by an average of ???12%. Most ages for pre-Pinedale (Bull Lake) boulders fall within marine-isotope stage (MIS) 5, a time when continental and Sierran ice accumulations were small or nonexistent. Under the assumption that these boulders were deposited on moraines that formed before the end of MIS 6 (???140 kyr BP), calculations indicated that rock-surface erosion rates would have had to range from 5.9 to 10.7 mm kyr-1 to produce the observed <span class="hlt">36</span><span class="hlt">Cl</span> values. When compared to rates that have been documented for the past 20 kyr, these erosion rates are extremely high. Snow shielding accounts for 0-48% of the additional years needed to shift pre-Pinedale dates to MIS 6. This suggests that some combination of snow shielding, sediment shielding, or <span class="hlt">36</span><span class="hlt">Cl</span> leakage has greatly decreased the apparent ages of most pre-Pinedale boulders. Inability to account for the effects of these processes seriously hinders the use of cosmogenic ages of pre-Pinedale boulders as estimators of the timing of alpine glaciation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016BVol...78...35A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016BVol...78...35A"><span id="translatedtitle">Evidence from cosmic ray exposure (CRE) dating for the existence of a pre-Minoan caldera on Santorini, Greece</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Athanassas, C. D.; Bourlès, D. L.; Braucher, R.; Druitt, T. H.; Nomikou, P.; Léanni, L.</p> <p>2016-05-01</p> <p>Cosmic ray exposure (CRE) dating was performed on the caldera cliffs of Santorini with the aim of detecting cliff segments predating the Minoan eruption (17th century BCE). The methodology involved the determination of in situ-produced cosmogenic <span class="hlt">36</span><span class="hlt">Cl</span> concentration in basaltic-to-rhyodacitic whole rocks cropping out in the cliffs. After the samples were processed following the chemical protocol of <span class="hlt">36</span><span class="hlt">Cl</span> preparation for silicate rocks, <span class="hlt">36</span><span class="hlt">Cl</span> concentrations were measured by accelerator mass spectrometry (AMS). Important challenges during the implementation procedure were related to large amounts of radiogenic <span class="hlt">36</span><span class="hlt">Cl</span>, complex modeling of inherited <span class="hlt">36</span><span class="hlt">Cl</span>, and dominance of the thermal and epithermal (low-energy) neutron capture production pathway. Nevertheless, quantitative assessments on the basis of the contribution of the low-energy neutron capture pathway percent to the total production rate validated the calculated CRE dates. Current CRE ages demonstrate that an ancient caldera existed on pre-Minoan Santorini, occupying at least the northern half of the modern-day caldera.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/765661','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/765661"><span id="translatedtitle">In Situ Production of Chlorine-36 in the Eastern Snake River Plain Aquifer, Idaho: Implications for Describing Ground-Water Contamination Near a Nuclear Facility</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>L. D. Cecil; L. L. Knobel; J. R. Green; S. K. Frape</p> <p>2000-06-01</p> <p>The purpose of this report is to describe the calculated contribution to ground water of natural, in situ produced <span class="hlt">36</span><span class="hlt">Cl</span> in the eastern Snake River Plain aquifer and to compare these concentrations in ground water with measured concentrations near a nuclear facility in southeastern Idaho. The scope focused on isotopic and chemical analyses and associated <span class="hlt">36</span><span class="hlt">Cl</span> in situ production calculations on 25 whole-rock samples from 6 major water-bearing rock types present in the eastern Snake River Plain. The rock types investigated were basalt, rhyolite, limestone, dolomite, shale, and quartzite. Determining the contribution of in situ production to <span class="hlt">36</span><span class="hlt">Cl</span> inventories in ground water facilitated the identification of the source for this radionuclide in environmental samples. On the basis of calculations reported here, in situ production of <span class="hlt">36</span><span class="hlt">Cl</span> was determined to be insignificant compared to concentrations measured in ground water near buried and injected nuclear waste at the INEEL. Maximum estimated <span class="hlt">36</span><span class="hlt">Cl</span> concentrations in ground water from in situ production are on the same order of magnitude as natural concentrations in meteoric water.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_17 --> <div id="page_18" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="341"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/956562','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/956562"><span id="translatedtitle">Chlorine-36 abundance in natural and synthetic perchlorate</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Heikoop, Jeffrey M; Dale, M; Sturchio, Neil C; Caffee, M; Belosa, A D; Heraty, Jr., L J; Bohike, J K; Hatzinger, P B; Jackson, W A; Gu, B</p> <p>2009-01-01</p> <p>Perchlorate (ClO{sub 4}{sup -}) is ubiquitous in the environment. It occurs naturally as a product of atmospheric photochemical reactions, and is synthesized for military, aerospace, and industrial applications. Nitrate-enriched soils of the Atacama Desert (Chile) contain high concentrations of natural ClO{sub 4}{sup -}; nitrate produced from these soils has been exported worldwide since the mid-1800's for use in agriculture. The widespread introduction of synthetic and agricultural ClO{sub 4}{sup -} into the environment has complicated attempts to understand the geochemical cycle of ClO{sub 4}{sup -}. Natural ClO{sub 4}{sup -} samples from the southwestern United States have relatively high {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> abundances ({sup <span class="hlt">36</span>}<span class="hlt">Cl</span>/Cl = 3,100 x 10{sup -15} to 28,800 x 10{sup -15}), compared with samples of synthetic ({sup <span class="hlt">36</span>}<span class="hlt">Cl</span>/Cl = 0.0 x 10{sup -15} to 40 x 10{sup -15}) and Atacama Desert ({sup <span class="hlt">36</span>}<span class="hlt">Cl</span>/Cl = 0.9 x 10{sup -15} to 590 x 10{sup -15}) ClO{sub 4}{sup -}. These data give a lower limit for the initial {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> abundance of natural ClO{sub 4}{sup -} and provide temporal and other constraints on its geochemical cycle.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/7993','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/7993"><span id="translatedtitle">Measurement of plutonium and other actinide elements at the center for accelerator mass spectrometry: a comparative assessments of competing techniques</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Hamilton, T H; McAninch, J</p> <p>1999-02-01</p> <p> initiatives. One potential measurement technique for meeting these requirements is accelerator mass spectrometry (AMS). AMS is a widely accepted analytical technique for measurement of isotopes such as 14 C, <span class="hlt">26</span> <span class="hlt">Al</span>, <span class="hlt">36</span> <span class="hlt">Cl</span> (Vogel et al., 1995) but has only recently been demonstrated for the quantitative detection of actinides (Fifield et al., 1996). The Center for Accelerator Mass Spectrometry (CAMS) at the Lawrence Livermore National Laboratory (LLNL) operates the most versatile and most productive AMS instrument in the world (Roberts et al., 1996). The addition of a Heavy Ion Beamline and associated hardware for actinide detection are in an advanced stage of development. Detection limits for actinide elements are expected to be on the order of 1 ´ 10 6 atoms (~0.5 fg) or lower with an initial measurement capacity of a few hundred samples per year. The ultimate detection sensitivity is expected to be ~1 ´ 10 5 atoms. Here we provide a review of non-conventional measurement techniquesÑincluding AMSÑfor the determination of low-levels of 239 Pu and other actinide elements in environmental samples. We include a discussion of potential measurement interferences and sample preparation requirements for the different techniques, and outline our proposed AMS system design and strategic approach for the development of low-level actinide detection capability at CAMS.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.1964S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.1964S"><span id="translatedtitle">Preliminary results on the deformation rates of the Malatya Fault (Malatya-Ovacık Fault Zone, Turkey)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sançar, Taylan; Zabcı, Cengiz; Akçar, Naki; Karabacak, Volkan; Yazıcı, Müge; Akyüz, Hüsnü Serdar; Öztüfekçi Önal, Ayten; Ivy-Ochs, Susan; Christl, Marcus; Vockenhuber, Christof</p> <p>2016-04-01</p> <p> resolution aerial photo-based DEMs and Terrestrial LiDAR measurements. In order to understand the temporal relationships of these different terrace treads, we collected samples for cosmogenic dating. Treads T2 and T4 were sampled for 10Be and <span class="hlt">26</span><span class="hlt">Al</span> isochron-burial dating method whereas T2 and T3 was sampled for <span class="hlt">36</span><span class="hlt">Cl</span> depth-profile. Also additional sampling was performed from T2 and T3 for U-Th analysis. The spatio-temporal relationships of these terrace treads will not only provide an understanding on the key faulting parameters such as horizontal and vertical deformation rates of the MF, but also will contribute to understanding of internal deformation of the Anatolian Scholle.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005AGUFM.U23B..06P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005AGUFM.U23B..06P"><span id="translatedtitle">Extracting in situ cosmogenic 14C from olivine: significance for the CRONUS-Earth project</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pigati, J. S.; Lifton, N. A.; Quade, J.; Jull, A. T.</p> <p>2005-12-01</p> <p>One of the main goals of the Cosmic-Ray-prOduced NUclide Systematics on Earth (CRONUS-Earth) project is to compare production rates of in situ cosmogenic nuclides (CNs) at several well-dated locations in various rock types. Quartz is the most commonly used target mineral for several CNs (e.g., 10Be, <span class="hlt">26</span><span class="hlt">Al</span>, 21Ne, 14C), but is generally absent in mafic volcanic terrains, where flows of different ages can constrain temporal variations in CN production at a given location. Because of its short half-life (5.73 ka), in situ cosmogenic 14C (in situ 14C) can be particularly useful for elucidating temporal variations in CN production over much shorter time scales than other CNs. While CNs such as <span class="hlt">36</span><span class="hlt">Cl</span> and 21Ne can be measured in both mafic and felsic rocks, clearly it would be advantageous to measure in situ 14C in mafic rocks as well. As such, we have worked to develop reliable protocols to extract in situ 14C from olivine. We conducted numerous stepped combustion experiments testing the efficacy of various chemical pretreatments. We were able to extract a stable and reproducible in situ 14C component from olivine using a LiBO2 flux, following pretreatment with dilute HNO3. However, measured concentrations in olivine (normalized to SiO2 composition) from two known-age basalt flows, the Tabernacle Hill flow (17.3+/-0.4 ka in age) in central Utah and the McCarty's flow (3.0+/-0.2 ka in age) in western New Mexico, were 3 to 5 times lower than predicted in situ 14C concentrations based on measurements in quartz. This discrepancy appears to arise from (1) a synthetic spinel-like mineral formed during our extraction process by the chemical interaction of the Al2O3 sample boat and olivine dissolved within the LiBO2 flux, and (2) undissolved pyroxene phenocrysts (difficult to separate in quantity from olivines). Although we do not fully understand how the formation of the synthetic mineral may affect carbon atoms liberated from olivine, the concentration of in situ 14C atoms that</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1995Metic..30R.596W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1995Metic..30R.596W"><span id="translatedtitle">A Single Lodranite/Acapulcoite Parent Body: Noble Gases in Lodranite QUE 93148 and Acapulcoite ALH 81261</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Weigel, A.; Eugster, O.; Marti, K.; Michel, R.</p> <p>1995-09-01</p> <p>We continue our comprehensive studies of the cosmic ray exposure history of lodranites [1] to include new noble gas measurements in the QUE 93148 lodranite and the ALH 81261 acapulcoite. In addition, we model the production rates of cosmogenic nuclides in lodranites and acapulcoites using the HERMES high energy transport code [2], in order to test whether conventional production rates can be extrapolated to this group of small meteoroids which reveal very large values of the shielding parameter 22Ne/21Ne (Table 1). The model calculations are based on the same excitation functions of p- and n-induced reactions as used in recent calculations [3,4]. We extended our studies to acapulcoites, since petrologic, mineralogic, and O-isotopic investigations [5] as well as chemical investigations [6] suggest that lodranites and acapulcoites are residues of varying degree of partial melting, consistent with an origin on a common parent body. Whether a collisional event on the common parent body ejected both types of meteorites can be investigated by an analysis of the transfer times to Earth, specifically their cosmic-ray exposure ages. Because the contents of trapped He, Ne, and Ar in lodranites and acapulcoites are very low we can derive reliable cosmogenic noble gas contents. Using the composition-adjusted production rates for cosmogenic noble gases in achondrites [7], and adopting the shielding-parameter dependence for H-chondrites the exposure ages of [1] are obtained. For lodranites these exposure ages overlap those calculated [8] from <span class="hlt">26</span><span class="hlt">Al</span> and 10Be measurements. For the acapulcoites our exposure ages agree with those [5] calculated with the Graf-model [9], as well as with the shielding-independent exposure age for Acapulco that is based on the <span class="hlt">36</span><span class="hlt">Cl</span>-36Ar method[10]. The large spread in the exposure ages can be attributed to the highly variable target element abundances, as multiple measurements on several aliquots show unusually large variations. The fact that the average</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1997PhDT........69F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1997PhDT........69F"><span id="translatedtitle">Aluminum-26 as a biological tracer using accelerator mass spectrometry</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Flarend, Richard Edward</p> <p>1997-06-01</p> <p>The development of accelerator mass spectrometry (AMS) has provided a practical method of detection for the only isotope of aluminum suitable as a tracer, <span class="hlt">26</span><span class="hlt">Al</span>. The use of <span class="hlt">26</span><span class="hlt">Al</span> as a tracer for aluminum has made possible the study of aluminum metabolism and the pharmacokinetics of aluminum-containing drugs at physiological levels. An overview of the various advantages of using <span class="hlt">26</span><span class="hlt">Al</span> as a tracer for aluminum and a general description of the AMS technique as applied to bio-medical applications is given. To illustrate the versatility of <span class="hlt">26</span><span class="hlt">Al</span> as a tracer for aluminum, <span class="hlt">26</span><span class="hlt">Al</span> studies of the past several years are discussed briefly. In addition, Two novel investigations dealing with <span class="hlt">26</span><span class="hlt">Al</span>-labeled drugs will be presented in more detail. In one of these studies, it was found that <span class="hlt">26</span><span class="hlt">Al</span> from aluminum hydroxide and aluminum phosphate vaccine adjuvants appeared in the blood just one hour after intramuscular injection. This is a surprising result since the currently held theory of how adjuvants work assumes that adjuvants remain insoluble and hold the antigen at the injection site for a long period of time. In another project, <span class="hlt">26</span><span class="hlt">Al</span>-labeled antiperspirants are being characterized by combining AMS with traditional analytical and chromatographic techniques. Future directions for this and other possible studies are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16949191','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16949191"><span id="translatedtitle">Aluminum bioavailability from the approved food additive leavening agent acidic sodium aluminum phosphate, incorporated into a baked good, is lower than from water.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Yokel, Robert A; Florence, Rebecca L</p> <p>2006-10-01</p> <p>There are estimates of oral aluminum (Al) bioavailability from drinking water, but little information on Al bioavailability from foods. Foods contribute approximately 95% and drinking water 1-2% of the typical human's daily Al intake. The objectives were to estimate oral Al bioavailability from a representative food containing the food additive acidic sodium aluminum phosphate (acidic SALP), a leavening agent in baked goods. Rats were acclimated to a special diet that resulted in no stomach contents 14 h after its withdrawal. They were trained to rapidly consume a biscuit containing 1.5% acidic SALP. Oral Al bioavailability was then determined from a biscuit containing 1% or 2% acidic SALP, synthesized to contain (<span class="hlt">26</span>)<span class="hlt">Al</span>. The rats received concurrent (27)Al infusion. Blood was repeatedly withdrawn and serum analyzed for (<span class="hlt">26</span>)<span class="hlt">Al</span> by accelerator mass spectrometry. Total Al was determined by atomic absorption spectrometry. Oral (<span class="hlt">26</span>)<span class="hlt">Al</span> bioavailability was determined from the area under the (<span class="hlt">26</span>)<span class="hlt">Al</span>, compared to (27)Al, serum concentrationxtime curves. Oral Al bioavailability (F) from biscuit containing 1% or 2% acidic (<span class="hlt">26</span>)<span class="hlt">Al</span>-SALP averaged approximately 0.11% and 0.13%; significantly less than from water, which was previously shown to be approximately 0.3%. The time to maximum serum (<span class="hlt">26</span>)<span class="hlt">Al</span> concentration was 4.2 and 6h after consumption of biscuit containing 1% or 2% (<span class="hlt">26</span>)<span class="hlt">Al</span>-acidic SALP, respectively, compared to 1-2h following (<span class="hlt">26</span>)<span class="hlt">Al</span> in water. These results of oral Al bioavailability from acidic (<span class="hlt">26</span>)<span class="hlt">Al</span>-SALP in a biscuit (F approximately 0.1%) and results from (<span class="hlt">26</span>)<span class="hlt">Al</span> in water (F approximately 0.3%) x the contributions of food and drinking water to the typical human's daily Al intake ( approximately 5-10mg from food and 0.1mg from water, respectively) suggest food provides approximately 25-fold more Al to systemic circulation, and potential Al body burden, than does drinking water.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004APS..DMP.D1068M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004APS..DMP.D1068M"><span id="translatedtitle">Counting individual Ca41 atoms with a MOT for biomedical applications</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Moore, I. D.; Bailey, K.; Mueller, P.; Lu, Z.-T.; O'Connor, T. P.; Young, L.; Geppert, Ch.; Wendt, K. D. A.</p> <p>2004-05-01</p> <p>An Atom Trap Trace Analysis (ATTA) system based on the technique of laser manipulation of neutral atoms has been used to count single atoms of ^<span class="hlt">41</span><span class="hlt">Ca</span> present in bio-medical samples. The isotopic abundance levels of ^<span class="hlt">41</span><span class="hlt">Ca</span> relative to ^40Ca of these samples range from 10-10 to 10-8. With its extremely low radioactivity due to its long lifetime, ^<span class="hlt">41</span><span class="hlt">Ca</span> has promising applications as a medical tracer in the research of bone metabolism. A comparison between ATTA and Resonance Ionization Mass Spectrometry (RIMS) has been performed to calibrate the system and demonstrate the validity of ATTA as a quantitative analysis tool. The technique is free from contamination from unwanted isotopes and isobars that have been limiting factors for other laser-based techniques. Details of the latest results will be discussed. This work is supported by the US Department of Energy, Office of Nuclear Physics, under contract W-31-109-ENG-38.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1990NIMPB..52..531E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1990NIMPB..52..531E"><span id="translatedtitle">Calcium-41 as a long-term biological tracer for bone resorption</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Elmore, David; Bhattacharyya, Maryka H.; Sacco-Gibson, Nancy; Peterson, David P.</p> <p>1990-12-01</p> <p>The use of <span class="hlt">41</span><span class="hlt">Ca</span> (half-life 1 × 10 5 yr) as a tracer for studying calcium metabolism in living systems is compared to the shorter-lived radionuclides 45Ca (165 d) and 47Ca (45 d) and the stable isotopes 42Ca and 44Ca. The feasibility of using accelerator mass spectrometry (AMS) measurements of <span class="hlt">41</span><span class="hlt">Ca</span> for studying multi-year calcium resorption in humans was tested as part of a companion study that used 45Ca to measure the effects of dietary cadmium on calcium metabolism in dogs. It was shown that Ca resorbed from prelabeled bones correlates well with 45Ca for a period of 28 weeks. The advantage of <span class="hlt">41</span><span class="hlt">Ca</span> is that, even with a negligible radiation dose, it can be measured by AMS long after the 45Ca becomes unmeasurable.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/15013386','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/15013386"><span id="translatedtitle">Feasibility of Using 36 C1 to Depict Water Infiltration at the Pit 7 Complex, LLNL Site 300</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Nimz, G J</p> <p>2002-01-25</p> <p>Measurements of bomb-pulse {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> and chloride concentrations in soils from the Pit 7 Complex basin, LLNL Site 300, combined with a demonstration model of moisture flux and infiltration rate, indicate that the bomb-pulse can be an extremely useful tool for the characterization of the unsaturated hydrology at Site 300. Bomb-pulse {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> is readily identifiable in the soil column, and exhibits moisture infiltration-related variations at different locations. It can be used to calibrate chloride accumulation models of unsaturated flow. In the continuing investigation of the origin and development of the Pit 7 Complex tritium plume, bomb-pulse {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> will provide a useful mechanism for hydrologic characterization.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/7114216','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/7114216"><span id="translatedtitle">K, Cl, and H2O entry in endolymph, perilymph, and cerebrospinal fluid of the rat.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sterkers, O; Saumon, G; Tran Ba Huy, P; Amiel, C</p> <p>1982-08-01</p> <p>The kinetics of radioactive potassium, chloride, and water entry into endolymph, perilymph, and cerebrospinal fluid were studied after intravenous administration of tracers in anesthetized and nephrectomized rats. Samples of cochlear endolymph, perilymph of scala vestibuli, perilymph of scala tympani, and cisternal cerebrospinal fluid were obtained. The data showed: 1) a rapid turnover of water in endolymph, perilymph, and cerebrospinal fluid, since 3H2O equilibrated with plasma in a few minutes; 2) a slow entry of 42K and <span class="hlt">36</span><span class="hlt">Cl</span> in perilymph, since <span class="hlt">36</span><span class="hlt">Cl</span> equilibrated with plasma after 2 h and 42K did not at 6 h; 3) an extremely slow entry of 42K and <span class="hlt">36</span><span class="hlt">Cl</span> in endolymph, since no equilibrium with plasma was obtained within the 5 h of the experiments. The comparison of the compartmental analysis of our data with the results of other studies using perilymphatic perfusion of tracers indicated that perilymph rather than plasma may be considered as the precursor of endolymph.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/970906','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/970906"><span id="translatedtitle">Chlorine-36 as a tracer of perchlorate origin</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Sturchio, N. C.; Caffee, M.; BelosoJr., Abelardo D.; Heraty, L. J.; Bohlke, J. K.; Hatzinger, Paul B.; Jackson, A.; Gu, Baohua</p> <p>2009-01-01</p> <p>Perchlorate (ClO{sub 4}{sup -}) is ubiquitous in the environment. It is produced naturally by atmospheric photochemical reactions, and also is synthesized in large quantities for military, aerospace, and industrial applications. Nitrate-enriched salt deposits of the Atacama Desert (Chile) contain high concentrations of natural ClO{sub 4}{sup -}, and have been exported worldwide since the mid-1800s for use in agriculture. The widespread introduction of synthetic and agricultural ClO{sub 4}{sup -} into the environment has contaminated numerous municipal water supplies. Stable isotope ratio measurements of Cl and O have been applied for discrimination of different ClO{sub 4}{sup -} sources in the environment. This study explores the potential of {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> measurements for further improving the discrimination of ClO{sub 4}{sup -} sources. Groundwater and desert soil samples from the southwestern United States (U.S.) contain ClO{sub 4}{sup -} having high {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> abundances ({sup <span class="hlt">36</span>}<span class="hlt">Cl</span>/Cl = 3100 x 10{sup -15} to 28,800 x 10{sup -15}), compared with those from the Atacama Desert ({sup <span class="hlt">36</span>}<span class="hlt">Cl</span>/Cl = 0.9 x 10{sup -15} to 590 x 10{sup -15}) and synthetic ClO{sub 4}{sup -} reagents and products ({sup <span class="hlt">36</span>}<span class="hlt">Cl</span>/Cl = 0.0 x 10{sup -15} to 40 x 10{sup -15}). In conjunction with stable Cl and O isotope ratios, {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> data provide a clear distinction among three principal ClO{sub 4}{sup -} source types in the environment of the southwestern U.S.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25171443','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25171443"><span id="translatedtitle">Perchlorate in the Great Lakes: isotopic composition and origin.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Poghosyan, Armen; Sturchio, Neil C; Morrison, Candice G; Beloso, Abelardo D; Guan, Yunbin; Eiler, John M; Jackson, W Andrew; Hatzinger, Paul B</p> <p>2014-10-01</p> <p>Perchlorate is a persistent and mobile contaminant in the environment with both natural and anthropogenic sources. Stable isotope ratios of oxygen (δ(18)O, Δ(17)O) and chlorine (δ(37)Cl) along with the abundance of the radioactive isotope (<span class="hlt">36</span>)<span class="hlt">Cl</span> were used to trace perchlorate sources and behavior in the Laurentian Great Lakes. These lakes were selected for study as a likely repository of recent atmospheric perchlorate deposition. Perchlorate concentrations in the Great Lakes range from 0.05 to 0.13 μg per liter. δ(37)Cl values of perchlorate from the Great Lakes range from +3.0‰ (Lake Ontario) to +4.0‰ (Lake Superior), whereas δ(18)O values range from -4.1‰ (Lake Superior) to +4.0‰ (Lake Erie). Great Lakes perchlorate has mass-independent oxygen isotopic variations with positive Δ(17)O values (+1.6‰ to +2.7‰) divided into two distinct groups: Lake Superior (+2.7‰) and the other four lakes (∼+1.7‰). The stable isotopic results indicate that perchlorate in the Great Lakes is dominantly of natural origin, having isotopic composition resembling that measured for indigenous perchlorate from preindustrial groundwaters of the western USA. The (<span class="hlt">36</span>)<span class="hlt">Cl</span>/Cl ratio of perchlorate varies widely from 7.4 × 10(-12) (Lake Ontario) to 6.7 × 10(-11) (Lake Superior). These (<span class="hlt">36</span>)<span class="hlt">Cl</span>O4(-) abundances are consistent with an atmospheric origin of perchlorate in the Great Lakes. The relatively high (<span class="hlt">36</span>)<span class="hlt">Cl</span>O4(-) abundances in the larger lakes (Lakes Superior and Michigan) could be explained by the presence of (<span class="hlt">36</span>)<span class="hlt">Cl</span>-enriched perchlorate deposited during the period of elevated atmospheric (<span class="hlt">36</span>)<span class="hlt">Cl</span> activity following thermonuclear bomb tests in the Pacific Ocean.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25171443','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25171443"><span id="translatedtitle">Perchlorate in the Great Lakes: isotopic composition and origin.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Poghosyan, Armen; Sturchio, Neil C; Morrison, Candice G; Beloso, Abelardo D; Guan, Yunbin; Eiler, John M; Jackson, W Andrew; Hatzinger, Paul B</p> <p>2014-10-01</p> <p>Perchlorate is a persistent and mobile contaminant in the environment with both natural and anthropogenic sources. Stable isotope ratios of oxygen (δ(18)O, Δ(17)O) and chlorine (δ(37)Cl) along with the abundance of the radioactive isotope (<span class="hlt">36</span>)<span class="hlt">Cl</span> were used to trace perchlorate sources and behavior in the Laurentian Great Lakes. These lakes were selected for study as a likely repository of recent atmospheric perchlorate deposition. Perchlorate concentrations in the Great Lakes range from 0.05 to 0.13 μg per liter. δ(37)Cl values of perchlorate from the Great Lakes range from +3.0‰ (Lake Ontario) to +4.0‰ (Lake Superior), whereas δ(18)O values range from -4.1‰ (Lake Superior) to +4.0‰ (Lake Erie). Great Lakes perchlorate has mass-independent oxygen isotopic variations with positive Δ(17)O values (+1.6‰ to +2.7‰) divided into two distinct groups: Lake Superior (+2.7‰) and the other four lakes (∼+1.7‰). The stable isotopic results indicate that perchlorate in the Great Lakes is dominantly of natural origin, having isotopic composition resembling that measured for indigenous perchlorate from preindustrial groundwaters of the western USA. The (<span class="hlt">36</span>)<span class="hlt">Cl</span>/Cl ratio of perchlorate varies widely from 7.4 × 10(-12) (Lake Ontario) to 6.7 × 10(-11) (Lake Superior). These (<span class="hlt">36</span>)<span class="hlt">Cl</span>O4(-) abundances are consistent with an atmospheric origin of perchlorate in the Great Lakes. The relatively high (<span class="hlt">36</span>)<span class="hlt">Cl</span>O4(-) abundances in the larger lakes (Lakes Superior and Michigan) could be explained by the presence of (<span class="hlt">36</span>)<span class="hlt">Cl</span>-enriched perchlorate deposited during the period of elevated atmospheric (<span class="hlt">36</span>)<span class="hlt">Cl</span> activity following thermonuclear bomb tests in the Pacific Ocean. PMID:25171443</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015NIMPB.361..627M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015NIMPB.361..627M"><span id="translatedtitle">Measurement of long-lived radionuclides in surface soil around F1NPP accident site by Accelerator Mass Spectrometry</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Miyake, Yasuto; Matsuzaki, Hiroyuki; Sasa, Kimikazu; Takahashi, Tsutomu</p> <p>2015-10-01</p> <p>In March 2011, vast amounts of radionuclides were released into the environment due to the Fukushima Daiichi Nuclear Power Plant (F1NPP) accident. However, very little work has been done concerning accident-derived long-lived nuclides such as 129I (T1/2 = 1.57 × 107 year) and <span class="hlt">36</span><span class="hlt">Cl</span> (T1/2 = 3.01 × 105 year). 129I and 131I are both produced by 235U fission in nuclear reactors. Being isotopes of iodine, these nuclides are expected to behave similarly in the environment. This makes 129I useful for retrospective reconstruction of 131I distribution during the initial stages of the accident. On the other hand, <span class="hlt">36</span><span class="hlt">Cl</span> is generated during reactor operation via neutron capture reaction of 35Cl, an impurity in the coolant or reactor component. Resulting <span class="hlt">36</span><span class="hlt">Cl</span>/Cl ratio within the reactor is thus much higher compared to that in environment. Similar to 129I, <span class="hlt">36</span><span class="hlt">Cl</span> is expected to have leaked out during the accident and it is important to evaluate its effects. In this study, 129I concentrations were determined in several surface soil samples collected around F1NPP. Average 129I/131I ratio was estimated to be 26.1 ± 5.8 as of March 11, 2011, consistent with calculations using ORIGEN2 code and other published data. <span class="hlt">36</span><span class="hlt">Cl</span>/Cl ratios in some of the soil samples were likewise measured and ranged from 1.1 × 10-12 to 2.6 × 10-11. These are higher compared to ratios measured around F1NPP before the accident. A positive correlation between <span class="hlt">36</span><span class="hlt">Cl</span> and 129I concentration was observed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/7953714','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/7953714"><span id="translatedtitle">Chloride permeability of rat brain membrane vesicles correlates with thiamine triphosphate content.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bettendorff, L; Hennuy, B; De Clerck, A; Wins, P</p> <p>1994-07-25</p> <p>Incubation of rat brain homogenates with thiamine or thiamine diphosphate (TDP) leads to a synthesis of thiamine triphosphate (TTP). In membrane vesicles subsequently prepared from the homogenates, increased TTP content correlates with increased <span class="hlt">36</span><span class="hlt">Cl</span>- uptake. A hyperbolic relationship was obtained with a K0.5 of 0.27 nmol TTP/mg protein. In crude mitochondrial fractions from the brains of animals previously treated with thiamine or sulbutiamine, a positive correlation between <span class="hlt">36</span><span class="hlt">Cl</span>- uptake and TTP content was found. These results, together with other results previously obtained with the patch-clamp technique, suggest that TTP is an activator of chloride channels having a large unit conductance. PMID:7953714</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1998NIMPA.265..558F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1998NIMPA.265..558F"><span id="translatedtitle">Radioassay of dual-labeled samples with a Cherenkov counting technique</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fujii, Haruo; Takiue, Makoto</p> <p>1998-03-01</p> <p>A new Cherenkov counting technique which allows radioactivities of a dual-labeled sample to be determined simultaneously by using a wavelength shifter has been proposed, and tested for the pairs 32P-<span class="hlt">36</span><span class="hlt">Cl</span> and 86Rb-<span class="hlt">36</span><span class="hlt">Cl</span>. The minimum requirements for this method are a single channel liquid scintillation counter, a wavelength shifter and a reference sample for determining the Cherenkov counting efficiency. The simple procedure for sample preparation and measurement makes the technique very useful for routine radioassay with the help of a desk-top computer.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1988NIMPA.265..558F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1988NIMPA.265..558F"><span id="translatedtitle">Radioassay of dual-labeled samples with a Cherenkov counting technique</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fujii, Haruo; Takiue, Makoto</p> <p>1988-03-01</p> <p>A new Cherenkov counting technique which allows radioactivities of a dual-labeled sample to be determined simultaneously by using a wavelength shifter has been proposed, and tested for the pairs 32P <span class="hlt">36</span><span class="hlt">Cl</span> and 86Rb <span class="hlt">36</span><span class="hlt">Cl</span>. The minimum requirements for this method are a single channel liquid scintillation counter, a wavelength shifter and a reference sample for determining the Cherenkov counting efficiency. The simple procedure for sample preparation and measurement makes the technique very useful for routine radioassay with the help of a desk-top computer.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21562555','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21562555"><span id="translatedtitle">EVIDENCE FOR MAGNESIUM ISOTOPE HETEROGENEITY IN THE SOLAR PROTOPLANETARY DISK</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Larsen, Kirsten K.; Trinquier, Anne; Paton, Chad; Schiller, Martin; Wielandt, Daniel; Connelly, James N.; Nordlund, Ake; Krot, Alexander N.; Bizzarro, Martin; Ivanova, Marina A.</p> <p>2011-07-10</p> <p>With a half-life of 0.73 Myr, the {sup <span class="hlt">26</span>}<span class="hlt">Al</span>-to-{sup 26}Mg decay system is the most widely used short-lived chronometer for understanding the formation and earliest evolution of the solar protoplanetary disk. However, the validity of {sup <span class="hlt">26</span>}<span class="hlt">Al</span>-{sup 26}Mg ages of meteorites and their components relies on the critical assumption that the canonical {sup <span class="hlt">26</span>}<span class="hlt">Al</span>/{sup 27}Al ratio of {approx}5 x 10{sup -5} recorded by the oldest dated solids, calcium-aluminium-rich inclusions (CAIs), represents the initial abundance of {sup <span class="hlt">26</span>}<span class="hlt">Al</span> for the solar system as a whole. Here, we report high-precision Mg-isotope measurements of inner solar system solids, asteroids, and planets demonstrating the existence of widespread heterogeneity in the mass-independent {sup 26}Mg composition ({mu}{sup 26}Mg*) of bulk solar system reservoirs with solar or near-solar Al/Mg ratios. This variability may represent heterogeneity in the initial abundance of {sup <span class="hlt">26</span>}<span class="hlt">Al</span> across the solar protoplanetary disk at the time of CAI formation and/or Mg-isotope heterogeneity. By comparing the U-Pb and {sup <span class="hlt">26</span>}<span class="hlt">Al</span>-{sup 26}Mg ages of pristine solar system materials, we infer that the bulk of the {mu}{sup 26}Mg* variability reflects heterogeneity in the initial abundance of {sup <span class="hlt">26</span>}<span class="hlt">Al</span> across the solar protoplanetary disk. We conclude that the canonical value of {approx}5 x 10{sup -5} represents the average initial abundance of {sup <span class="hlt">26</span>}<span class="hlt">Al</span> only in the CAI-forming region, and that large-scale heterogeneity-perhaps up to 80% of the canonical value-may have existed throughout the inner solar system. If correct, our interpretation of the Mg-isotope composition of inner solar system objects precludes the use of the {sup <span class="hlt">26</span>}<span class="hlt">Al</span>-{sup 26}Mg system as an accurate early solar system chronometer.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/pages/biblio/1259784-bone-equally-responsive-calcium-vitamin-intake-from-food-vs-supplements-use-tracer-kinetic-model','SCIGOV-DOEP'); return false;" href="http://www.osti.gov/pages/biblio/1259784-bone-equally-responsive-calcium-vitamin-intake-from-food-vs-supplements-use-tracer-kinetic-model"><span id="translatedtitle">Is bone equally responsive to calcium and vitamin D intake from food vs. supplements? Use of 41calcium tracer kinetic model</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Rogers, Tara S.; Garrod, Marjorie G.; Peerson, Janet M.; Hillegonds, Darren J.; Buchholz, Bruce A.; Demmer, Elieke; Richardson, Christine; Gertz, Erik R.; Van Loan, Marta D.</p> <p>2016-05-09</p> <p>Few interventions directly compare equivalent calcium and vitamin D from dairy vs. supplements on the same bone outcomes. Here, the radioisotope calcium-41 (<span class="hlt">41</span><span class="hlt">Ca</span>) holds promise as a tracer method to directly measure changes in bone resorption with differing dietary interventions.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_18 --> <div id="page_19" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015NIMPB.361..358J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015NIMPB.361..358J"><span id="translatedtitle">Biomedical graphite and CaF2 preparation and measurement at PRIME Lab</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jackson, George S.; Einstein, Jane A.; Kubley, Tom; Martin, Berdine; Weaver, Connie M.; Caffee, Marc</p> <p>2015-10-01</p> <p>The biomedical program at PRIME Lab has prepared radiocarbon and <span class="hlt">41</span><span class="hlt">Ca</span> as tracers for a variety of applications. Over the last decade several hundred 14C samples and several thousand <span class="hlt">41</span><span class="hlt">Ca</span> samples have been measured per year. Biomedical samples pose challenges that are relatively rare in the AMS community. We will discuss how to prepare and compensate for samples that have isotope ratios above the dynamic range of AMS, high interference rates, and small samples sizes. In the case of <span class="hlt">41</span><span class="hlt">Ca</span>, the trade off in the chromatography between yield and sample cleanliness will be analyzed. Secondary standards that have isotope ratios commonly encountered in our applications are routinely prepared. We use material from the Joint Research Centre's Institute for Reference Materials and Measurement: IRMM-3701/4, 3701/5, and 3701/6 and a standard produced by PRIME Lab for <span class="hlt">41</span><span class="hlt">Ca</span>. We use International Atomic Energy Agency's IAEA C-3, IAEA C-7, IAEA C-8, and a ∼12.5× modern oxalic acid secondary standard supplied by Lawrence Livermore National Laboratory for 14C. We will discuss our precision, reproducibility, and the relative agreement between our measured and the reported values for these materials.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2012-title10-vol2/pdf/CFR-2012-title10-vol2-part110-appL.pdf','CFR2012'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2012-title10-vol2/pdf/CFR-2012-title10-vol2-part110-appL.pdf"><span id="translatedtitle">10 CFR Appendix L to Part 110 - Illustrative List of Byproduct Materials Under NRC Export/Import Licensing Authority a</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2012&page.go=Go">Code of Federal Regulations, 2012 CFR</a></p> <p></p> <p>2012-01-01</p> <p>...) Cesium 129 (Cs 129) Cesium 131 (Cs 131) Cesium 134m (Cs 134m) Cesium 134 (Cs 134) Cesium 135 (Cs 135) Cesium 136 (Cs 136) Cesium 137 (Cs 137) Chlorine <span class="hlt">36</span> (<span class="hlt">Cl</span> 36) Chlorine 38 (Cl 38) Chromium 51 (Cr...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2014-title10-vol2/pdf/CFR-2014-title10-vol2-part110-appL.pdf','CFR2014'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2014-title10-vol2/pdf/CFR-2014-title10-vol2-part110-appL.pdf"><span id="translatedtitle">10 CFR Appendix L to Part 110 - Illustrative List of Byproduct Materials Under NRC Export/Import Licensing Authority a</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2014&page.go=Go">Code of Federal Regulations, 2014 CFR</a></p> <p></p> <p>2014-01-01</p> <p>...) Cesium 129 (Cs 129) Cesium 131 (Cs 131) Cesium 134m (Cs 134m) Cesium 134 (Cs 134) Cesium 135 (Cs 135) Cesium 136 (Cs 136) Cesium 137 (Cs 137) Chlorine <span class="hlt">36</span> (<span class="hlt">Cl</span> 36) Chlorine 38 (Cl 38) Chromium 51 (Cr...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2011-title10-vol2/pdf/CFR-2011-title10-vol2-part110-appL.pdf','CFR2011'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2011-title10-vol2/pdf/CFR-2011-title10-vol2-part110-appL.pdf"><span id="translatedtitle">10 CFR Appendix L to Part 110 - Illustrative List of Byproduct Materials Under NRC Export/Import Licensing Authority a</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2011 CFR</a></p> <p></p> <p>2011-01-01</p> <p>...) Cesium 129 (Cs 129) Cesium 131 (Cs 131) Cesium 134m (Cs 134m) Cesium 134 (Cs 134) Cesium 135 (Cs 135) Cesium 136 (Cs 136) Cesium 137 (Cs 137) Chlorine <span class="hlt">36</span> (<span class="hlt">Cl</span> 36) Chlorine 38 (Cl 38) Chromium 51 (Cr...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/572205','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/572205"><span id="translatedtitle">Chlorine-36 investigations of groundwater infiltration in the Exploratory Studies Facility at Yucca Mountain, Nevada</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Levy, S.S.; Fabryka-Martin, J.T.; Dixon, P.R.; Liu, B.; Turin, H.J.; Wolfsberg, A.V.</p> <p>1997-12-31</p> <p>Chlorine-36, including the natural cosmogenic component and the component produced during atmospheric nuclear testing in the 1950`s and 1960`s (bomb pulse), is being used as an isotopic tracer for groundwater infiltration studies at Yucca Mountain, a potential nuclear waste repository. Rock samples have been collected systematically in the Exploratory Studies Facility (ESF), and samples were also collected from fractures, faults, and breccia zones. Isotopic ratios indicative of bomb-pulse components in the water ({sup <span class="hlt">36</span>}<span class="hlt">Cl</span>/Cl values > 1,250 {times} 10{sup {minus}15}), signifying less than 40-yr travel times from the surface, have been detected at a few locations within the Topopah Spring Tuff, the candidate host rock for the repository. The specific features associated with the high {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>/Cl values are predominantly cooling joints and syngenetic breccias, but most of the sites are in the general vicinity of faults. The non-bomb pulse samples have {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>/Cl values interpreted to indicate groundwater travel times of at least a few thousand to possibly several hundred thousand years. Preliminary numerical solute-travel experiments using the FEHM (Finite Element Heat and Mass transfer) code demonstrate consistency between these interpreted ages and the observed {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>/Cl values but do not validate the interpretations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/555352','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/555352"><span id="translatedtitle">Chlorine-36 investigations of groundwater infiltration in the Exploratory Studies Facility at Yucca Mountain, Nevada</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Levy, S.S.; Fabryka-Martin, J.T.; Dixon, P.R.; Liu, B.; Turin, H.J.; Wolfsberg, A.V.</p> <p>1997-12-01</p> <p>Chlorine-36, including the natural cosmogenic component and the component produced during atmospheric nuclear testing in the 1950`s and 1960`s (bomb pulse), is being used as an isotopic tracer for groundwater infiltration studies at Yucca Mountain, a potential nuclear waste repository. Rock samples have been collected systematically in the Exploratory Studies Facility (ESF), and samples were also collected from fractures, faults, and breccia zones. Isotopic ratios indicative of bomb-pulse components in the water ({sup <span class="hlt">36</span>}<span class="hlt">Cl</span>/Cl values > 1,250 x 10{sup {minus}15}), signifying less than 40-yr travel times from the surface, have been detected at a few locations within the Topopah Spring Tuff, the candidate host rock for the repository. The specific features associated with the high {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>/Cl values are predominantly cooling joints and syngenetic breccias, but most of the sites are in the general vicinity of faults. The non-bomb pulse samples have {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>/Cl values interpreted to indicate groundwater travel times of at least a few thousand to possibly several hundred thousand years. Preliminary numerical solute-travel experiments using the FEHM (Finite Element Heat and Mass transfer) code demonstrate consistency between these interpreted ages and the observed {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>/Cl values but do not validate the interpretations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/12380071','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12380071"><span id="translatedtitle">Characterization of high molecular weight disinfection byproducts resulting from chlorination of aquatic humic substances.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhang, Xiangru; Minear, Roger A</p> <p>2002-10-01</p> <p>Aquatic humic substances react with chlorine to produce numerous disinfection byproducts (DBPs) during chlorination of drinking water. Although low molecular weight (MW) chlorinated DBPs have been intensively studied over the past several decades, relatively little is known about high MW chlorinated DBPs (above 500 Da) that may be associated with adverse health implications. In this work, carrier-free radioactive <span class="hlt">36</span><span class="hlt">Cl</span> was introduced into a Suwannee River fulvic acid sample to label the chlorine-containing DBPs. By combining the fractionation techniques of ultrafiltration (UF) and size exclusion chromatography (SEC) with the detection of <span class="hlt">36</span><span class="hlt">Cl</span>, UV, and dissolved organic carbon (DOC), the high MW region in the SEC-<span class="hlt">36</span><span class="hlt">Cl</span> profiles of the chlorinated sample with and without UF was defined. SEC-UV and SEC-DOC profiles were found to be approximately indicative of SEC-<span class="hlt">36</span><span class="hlt">Cl</span> profiles for the high MW region. The MW distribution shows that the high MW chlorinated DBPs were highly dispersed with an average MW around 2000 Da based on calibration with polystyrene sulfonate standards. The Cl/C atomic ratios of the high MW DBPs were roughly constant (0.025), which is much lower than those of the common known chlorinated DBPs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19039925','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19039925"><span id="translatedtitle">Cl- conduction of GABA(A)-receptor complex of synaptic membranes of rat brain cortex after development of chronic epileptization of the brain (pharmacological kindling).</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rebrov, I G; Karpova, M N; Andreev, A A; Klishina, N Y; Kalinina, M V; Kusnetzova, L V</p> <p>2008-03-01</p> <p>Experiments on Wistar rats showed that basal and muscimol-induced <span class="hlt">36</span><span class="hlt">Cl</span>- entry into synaptoneurosomes isolated from the brain cortex decreased after kindling (30 mg/kg pentylenetetrazole intraperitoneally for 30 days) in animals with seizure severity score 4-5. Changes in Cl- conduction during kindling are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18683491','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18683491"><span id="translatedtitle">Cl(-) conduction of GABAA receptor complex of synaptic membranes in the cortex of rats at the middle stage of chronic cerebral epileptization (pharmacological kindling).</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rebrov, I G; Karpova, M N; Andreev, A A; Klishina, N Yu; Kalinina, M V; Kusnetzova, L V</p> <p>2007-11-01</p> <p>Experiments on Wistar rats showed a decrease in basal and muscimol-stimulated <span class="hlt">36</span><span class="hlt">Cl</span>(-) entry into synaptoneurosomes isolated from the cerebral cortex during the middle stage of kindling (30 mg/kg pentylenetetrazole intraperitoneally for 14 days) characterized by the development of convulsions of higher (2 points) severity in comparison with the previous stage.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006CzJPh..56D.211R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006CzJPh..56D.211R"><span id="translatedtitle">Radiochemical analysis of chlorine-36</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rodríguez, M.; Piña, G.; Lara, E.</p> <p>2006-01-01</p> <p>The radioactive chlorine isotope, <span class="hlt">36</span><span class="hlt">Cl</span>, decays with a half-life of 3×105 years by emitting a beta particle (98 %) and by electron capture. The aim of this paper is to propose a radiochemical separation method of <span class="hlt">36</span><span class="hlt">Cl</span> from the other beta-gamma emitters present in low and medium radioactive wastes such as spent ion exchange resins and evaporator concentrates, that arise from Nuclear Power Plants and particularly in the wastes that come from decommissioning activities of graphite reactors, in order to provide data for <span class="hlt">36</span><span class="hlt">Cl</span> inventory calculations. The separation method proposed is based on an oxidation technique where chlorine is trapped by NaOH. <span class="hlt">36</span><span class="hlt">Cl</span> beta emissions are measured by liquid scintillation counting by the dual label technique in order to avoid the contamination produced by 14C which is also trapped by NaOH and which is the main contaminant present in graphite samples. The sensitivity of this method is sufficient to achieve the needed thresholds for the radiological characterization of the radioactive materials to which this method can be applied.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/publication/?seqNo115=319230','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=319230"><span id="translatedtitle">Distribution and chemical fate of chlorine dioxide gas during sanitation of tomatoes and cantaloupe</span></a></p> <p><a target="_blank" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p></p> <p></p> <p>A series of studies was conducted to establish the 1) distribution and chemical fate of <span class="hlt">36</span>-<span class="hlt">Cl</span>O2 on tomatoes and cantaloupe; and 2) the magnitude of residues in kilogram quantities of tomatoes and cantaloupe sanitized with a slow-release chlorine dioxide formulation. Tomatoes and cantaloupe were resp...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70023717','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70023717"><span id="translatedtitle">Chlorine-36, bromide, and the origin of spring water</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Davis, S.N.; Cecil, L.D.; Zreda, M.; Moysey, S.</p> <p>2001-01-01</p> <p>Natural ratios of chlorine-36 (<span class="hlt">36</span><span class="hlt">Cl</span>) to stable chlorine (i.e., <span class="hlt">36</span><span class="hlt">Cl</span>/Cl ?? 10-15) vary in shallow groundwater of the United States from about 50 in coastal areas to about 1400 in the northern Rocky Mountains. Ratios lower than these indicate the presence of chloride (Cl-) that has been isolated from the atmosphere for hundreds of thousands of years, if not longer. Higher ratios, which can exceed 5000, usually originate from fallout from testing thermonuclear devices in the western Pacific in the 1950s. Natural mass ratios of chloride to bromide (Cl-/Br-) in precipitation vary in the United States from about 250 in coastal areas to about 50 in the north-central states. Lower ratios may suggest contamination from human sources. Higher ratios, which may exceed 2000, commonly reflect the dissolution of halite. Seawater has a Cl-/Br- ratio of 290. Both <span class="hlt">36</span><span class="hlt">Cl</span> and Cl-/Br- ratios have been measured in 21 samples of spring water collected from springs in 10 different states. Brackish water from Saratoga Springs area in New York has low values for both <span class="hlt">36</span><span class="hlt">Cl</span> and Cl-/Br- ratios. This indicates that a large component of the water has a very deep origin. Brackish water from Alexander Springs in Florida has a low <span class="hlt">36</span><span class="hlt">Cl</span> ratio but a high Cl-/Br- ratio similar to seawater. This suggests the addition of ancient seawater that may be trapped in the aquifer. Big Spring in Iowa discharges water with a very high Cl-/Br- ratio but a moderate <span class="hlt">36</span><span class="hlt">Cl</span> ratio. The high ratio of Cl-/Br- may be produced by dissolution of road salt or agricultural chemicals. Of the 21 springs sampled, only 10 appeared to have potable water not significantly affected by human activity. Chlorine-36 from testing of nuclear devices is still being flushed out of four of the spring systems that were sampled. Thus, more than 45 years have passed since <span class="hlt">36</span><span class="hlt">Cl</span> was introduced into the aquifers feeding the springs and the systems, as yet, have not been purged. Published by Elsevier Science B.V.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/838971','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/838971"><span id="translatedtitle">Cosmogenic, radiogenic, and stable isotopic constraints on groundwater residence time in the nubian aquifer, western desert of egypt</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Patterson, Leslie J.; Sturchio, Neil C.; Kennedy, B.Mack; van Soest, Matthias C.; Sultan, Mohamed; Lu, Zheng-Tian; Lehmann, Bernhard; Purtschert, Roland; El Alfy, Zeinhom; El Kaliouby, Baher; Dawood, Yehia; Abdallah, Ali</p> <p>2004-06-01</p> <p>Measurements of radiochlorine ({sup <span class="hlt">36</span>}<span class="hlt">Cl</span>), radiogenic noble gases ({sup 4}He and {sup 40}Ar), and stable chlorine isotope ratios were obtained to assess the residence time of groundwater in the Nubian Aquifer of the Western Desert of Egypt. Measured {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>/Cl ratios yield apparent residence times from {approx}0.2 to 1.2 x 10{sup 6} years in the deep (600-1200 m) groundwater (assuming constant Cl) and {le} 0.16 x 10{sup 6} years in the shallow (<600 m) groundwater. Values of {delta}{sup 37}Cl in the groundwater strengthen the application of the {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> dating method by constraining Cl sources and identifying groundwater mixing. Dissolved gases were measured in some of the deep groundwater samples. Measured {sup 4}He concentrations indicate accumulation of radiogenic {sup 4}He that is qualitatively consistent with the age progression indicated by the {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>/Cl ratios, but the flux of external {sup 4}He from the underlying crust has not been quantified and is not constant throughout the aquifer. Concentrations of {sup 40}Ar range from 3.3 to 6.7 x 10{sup -4} ccSTP/g and indicate excess air incorporation at recharge. Measured {sup 40}Ar/{sup 36}Ar ratios do not exceed the atmospheric ratio. A two-dimensional numerical hydrodynamic transect of the aquifer was modeled from the area of the Uweinat Uplift to the northern Bahariya Oasis. Predicted groundwater velocities in the deep portion of the aquifer are 0.5-3.5 m/yr with groundwater residence times up to 9 x 10{sup 5} years; residence times up to 1.3 x 10{sup 6} years are predicted in the confining shale. Aquifer properties are estimated by using the model to fit the measured {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>/Cl ratios. Under these conditions, hydrodynamic residence times are within about 30 percent of those calculated from {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> when mixing of Cl{sup -} is accounted for in the highest-Cl{sup -} deep groundwaters. By mutually calibrating multiple methods (hydrodynamic, {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>, and {sup 4}He), a consistent picture of the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20185683','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20185683"><span id="translatedtitle">Constraints on the formation age of cometary material from the NASA Stardust mission.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Matzel, J E P; Ishii, H A; Joswiak, D; Hutcheon, I D; Bradley, J P; Brownlee, D; Weber, P K; Teslich, N; Matrajt, G; McKeegan, K D; MacPherson, G J</p> <p>2010-04-23</p> <p>We measured the <span class="hlt">26</span><span class="hlt">Al</span>-26Mg isotope systematics of a approximately 5-micrometer refractory particle, Coki, returned from comet 81P/Wild 2 in order to relate the time scales of formation of cometary inclusions to their meteoritic counterparts. The data show no evidence of radiogenic 26Mg and define an upper limit to the abundance of <span class="hlt">26</span><span class="hlt">Al</span> at the time of particle formation: <span class="hlt">26</span><span class="hlt">Al</span>/27Al < 1 x 10(-5). The absence of <span class="hlt">26</span><span class="hlt">Al</span> indicates that Coki formed >1.7 million years after the oldest solids in the solar system, calcium- and aluminum-rich inclusions (CAIs). The data suggest that high-temperature inner solar system material formed, was subsequently transferred to the Kuiper Belt, and was incorporated into comets several million years after CAI formation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/980892','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/980892"><span id="translatedtitle">Constraints on the Formation Age of Cometary Material from the NASA Stardust Mission</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Matzel, J; Ishii, H; Joswiak, D; Hutcheon, I; Bradley, J; Brownlee, D; Weber, P K; Teslich, N; Matrajt, G; McKeegan, K; MacPherson, G</p> <p>2009-11-13</p> <p>We measured the {sup <span class="hlt">26</span>}<span class="hlt">Al</span>-{sup 26}Mg isotope systematics of a {approx} 5-micrometer refractory particle, Coki, returned from comet 81P/Wild 2 in order to relate the time scales of formation of cometary inclusions to their meteoritic counterparts. The data show no evidence of radiogenic {sup 26}Mg and define an upper limit to the abundance of {sup <span class="hlt">26</span>}<span class="hlt">Al</span> at the time of particle formation: {sup <span class="hlt">26</span>}<span class="hlt">Al</span>/{sup 27}Al < 1 x 10-5. The absence of {sup <span class="hlt">26</span>}<span class="hlt">Al</span> indicates that Coki formed >1.7 million years after the oldest solids in the solar system, calcium- and aluminum-rich inclusions (CAIs). The data suggest that high-temperature inner solar system material formed, was subsequently transferred to the Kuiper Belt, and was incorporated into comets several million years after CAI formation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70029101','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70029101"><span id="translatedtitle">New data for Late Pleistocene Pinedale alpine glaciation from southwestern Colorado</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Benson, L.; Madole, R.; Landis, G.; Gosse, J.</p> <p>2005-01-01</p> <p>New cosmogenic surface-exposure ages of moraine-crest boulders from southwestern Colorado are compared with published surface-exposure ages of boulders from moraine complexes in north-central Colorado and in west-central (Fremont Lake basin) Wyoming. 10Be data sets from the three areas were scaled to a single 10Be production rate of 5.4 at/g/yr at sea level and high latitude (SLHL), which represents the average 10Be production rate for two high-altitude, mid-latitude sites in the western United States (US) and Austria. Multiple nuclide ages on single boulders indicate that this 10Be production rate yields ages comparable to those calculated with a commonly used <span class="hlt">36</span><span class="hlt">Cl</span> production scheme. The average age and age range of moraine-crest boulders on terminal moraines at the southwestern Colorado and Wyoming sites are similar, indicating a retreat from their positions ???16.8 <span class="hlt">36</span><span class="hlt">Cl</span> ka (Cosmogenic ages in this paper are labeled 10Be or <span class="hlt">36</span><span class="hlt">Cl</span> ka or just ka when both 10Be or <span class="hlt">36</span><span class="hlt">Cl</span> ages are being discussed; radiocarbon ages are labeled 14C ka, calibrated radiocarbon are labeled cal ka, and calendar ages are labeled calendar ka. Errors (??1??) associated with ages are shown in tables. Radiocarbon ages were calibrated using the data of Hughen et al. (Science 303 (2004) 202). This suggests a near-synchronous retreat of Pinedale glaciers across a 470-km latitudinal range in the Middle and Southern Rocky Mountains. Hypothetical corrections for snow shielding and rock-surface erosion shifts the time of retreat to between 17.2 and 17.5 10Be ka at Pinedale, Wyoming, and between 16.3 and 17.3 <span class="hlt">36</span><span class="hlt">Cl</span> ka at Hogback Mountain, Colorado. ?? 2004 Elsevier Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17399863','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17399863"><span id="translatedtitle">Radiochlorine concentration ratios for agricultural plants in various soil conditions.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kashparov, V; Colle, C; Levchuk, S; Yoschenko, V; Zvarich, S</p> <p>2007-01-01</p> <p>Long-term field experiments have been carried out in the Chernobyl exclusion zone in order to determine the parameters governing radiochlorine ((<span class="hlt">36</span>)<span class="hlt">Cl</span>) transfer to plants from four types of soil, namely, Podzoluvisol, Greyzem, Phaeozem and Chernozem. Radiochlorine concentration ratios (CR=concentration of (<span class="hlt">36</span>)<span class="hlt">Cl</span> in the fresh plant material divided by its concentration in the dried soil in the upper 20 cm layer) were obtained in green peas (2.6+/-0.4), onions (1.5+/-0.5), potatoes (8+/-1), clover (90+/-26) and ryegrass (158+/-88) hay, oat seeds (36+/-23) and straw (305+/-159), wheat seeds (35+/-10) and straw (222+/-82). These values correlate with the stable chlorine values for the same plants. It was shown that (<span class="hlt">36</span>)<span class="hlt">Cl</span> plant/soil CR in radish roots (CR=9.7+/-1.4) does not depend on the stable chlorine content in the soil (up to 150 mgkg(-1)), soil type and thus, that stable chlorine CR values (9.4+/-1.2) can also be used for (<span class="hlt">36</span>)<span class="hlt">Cl</span>. Injection of additional quantities of stable chlorine into the soil (100 mgkg(-1) of dry soil) with fertilizer does not change the soil-to-plant transfer of (<span class="hlt">36</span>)<span class="hlt">Cl</span>. The results from a batch experiment showed that chlorine is retained in the investigated soils only by live biota and transfers quickly (in just a few hours) into the soil solution from dry vegetation even without decomposition of dead plants and is integrated in the migration processes in soil.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6409361','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6409361"><span id="translatedtitle">Proton-stimulated Cl-HCO/sub 3/ antiport by basolateral membrane vesicles of lobster hepatopancreas</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Ahearn, G.A.; Grover, M.L.; Tsuji, R.T.; Clay, L.P.</p> <p>1987-05-01</p> <p>Purified epithelial basolateral membrane vesicles were prepared from lobster hepatopancreas by sorbitol gradient centrifugation. Na+-K+-adenosinetriphosphatase, alkaline phosphatase, and cytochrome-c oxidase enzyme activities in the final membrane preparation were enriched 9.6-, 1.4-, and 0.4-fold, respectively, compared with their activities in the original tissue homogenate. Vesicle osmotic reactivity was demonstrated using 60-min equilibrium /sup <span class="hlt">36</span>/<span class="hlt">Cl</span> uptake experiments at a variety of transmembrane osmotic gradients. /sup <span class="hlt">36</span>/<span class="hlt">Cl</span> uptake into vesicles preloaded with HCO/sub 3/ was significantly greater than into vesicles lacking HCO/sub 3/. This exchange process was stimulated by a transmembrane proton gradient (internal pH greater than external pH). Proton-gradient-dependent Cl-HCO/sub 3/ exchange was potential sensitive and stimulated by an electrically negative vesicle interior. /sup <span class="hlt">36</span>/<span class="hlt">Cl</span> influx (4-s exposures) into HCO/sub 3/-loaded vesicles occurred by the combination of 4-acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic acid sensitive, carrier-mediated transfer and apparent diffusion. /sup <span class="hlt">36</span>/<span class="hlt">Cl</span> influx was a hyperbolic function of both internal (HCO/sub 3/) and internal (Cl). The two internal anions displayed a 100-fold difference in apparent affinity constants with HCO/sub 3/ being strongly preferred. /sup <span class="hlt">36</span>/<span class="hlt">Cl</span> influx was stimulated more by preloaded monovalent than by divalent anions. Na was an inhibitor of proton-dependent anion antiport, whereas K had no effect. A model for HCl-HCO/sub 3/ antiport is suggested that employs combined transmembrane concentration gradients of Cl and HCO/sub 3/ to power anion exchange and transfer protons against a concentration gradient.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70025671','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70025671"><span id="translatedtitle">Chlorine-36 data at Yucca Mountain: Statistical tests of conceptual models for unsaturated-zone flow</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Campbell, K.; Wolfsberg, A.; Fabryka-Martin, J.; Sweetkind, D.</p> <p>2003-01-01</p> <p>An extensive set of chlorine-36 (<span class="hlt">36</span><span class="hlt">Cl</span>) data has been collected in the Exploratory Studies Facility (ESF), an 8-km-long tunnel at Yucca Mountain, Nevada, for the purpose of developing and testing conceptual models of flow and transport in the unsaturated zone (UZ) at this site. At several locations, the measured values of <span class="hlt">36</span><span class="hlt">Cl</span>/Cl ratios for salts leached from rock samples are high enough to provide strong evidence that at least a small component of bomb-pulse <span class="hlt">36</span><span class="hlt">Cl</span>, fallout from atmospheric testing of nuclear devices in the 1950s and 1960s, was measured, implying that some fraction of the water traveled from the ground surface through 200-300 m of unsaturated rock to the level of the ESF during the last 50 years. These data are analyzed here using a formal statistical approach based on log-linear models to evaluate alternative conceptual models for the distribution of such fast flow paths. The most significant determinant of the presence of bomb-pulse <span class="hlt">36</span><span class="hlt">Cl</span> in a sample from the welded Topopah Spring unit (TSw) is the structural setting from which the sample was collected. Our analysis generally supports the conceptual model that a fault that cuts through the nonwelded Paintbrush tuff unit (PTn) that overlies the TSw is required in order for bomb-pulse <span class="hlt">36</span><span class="hlt">Cl</span> to be transmitted to the sample depth in less than 50 years. Away from PTn-cutting faults, the ages of water samples at the ESF appear to be a strong function of the thickness of the nonwelded tuff between the ground surface and the ESF, due to slow matrix flow in that unit. ?? 2002 Elsevier Science B.V. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21367227','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21367227"><span id="translatedtitle">Coulomb dissociation of {sup 27} P</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Beceiro, S.; Cortina-Gil, D.; Suemmerer, K.</p> <p>2010-04-26</p> <p>The {sup <span class="hlt">26</span>}<span class="hlt">Al</span> nucleus has a shorter life-time than the Universe showing that the nucleosynthesis of this element might be an ongoing process in stars. The reaction {sup 26}Si(p,gamma){sup 27} P competes with the production of {sup <span class="hlt">26</span>}<span class="hlt">Al</span>. Coulomb dissociation of {sup 27} P is an indirect method to measure that reaction. An experiment was performed at GSI with a {sup 36}Ar primary beam at 500 MeV to measure this reaction.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_19 --> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006ApJ...639.1227K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006ApJ...639.1227K"><span id="translatedtitle">Aluminum-Magnesium and Oxygen Isotope Study of Relict Ca-Al-rich Inclusions in Chondrules</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Krot, Alexander N.; McKeegan, Kevin D.; Huss, Gary R.; Liffman, Kurt; Sahijpal, Sandeep; Hutcheon, Ian D.; Srinivasan, Gopalan; Bischoff, Adolph; Keil, Klaus</p> <p>2006-03-01</p> <p>Relict Ca-Al-rich inclusions (CAIs) in chondrules crystallized before their host chondrules and were subsequently partly melted together with chondrule precursors during chondrule formation. Like most CAIs, relict CAIs are 16O enriched (Δ17O<-20‰) compared to their host chondrules (Δ17O>-9‰). Hibonite in a relict CAI from the ungrouped carbonaceous chondrite Adelaide has a large excess of radiogenic 26Mg (26Mg*) from the decay of <span class="hlt">26</span><span class="hlt">Al</span>, corresponding to an initial <span class="hlt">26</span><span class="hlt">Al</span>/27Al ratio [(<span class="hlt">26</span><span class="hlt">Al</span>/27Al)I] of (3.7+/-0.5)×10-5 in contrast, melilite in this CAI and plagioclase in the host chondrule show no evidence for 26Mg* [(<span class="hlt">26</span><span class="hlt">Al</span>/27Al)I of <5×10-6]. Grossite in a relict CAI from the CH carbonaceous chondrite PAT 91546 has little 26Mg*, corresponding to a (<span class="hlt">26</span><span class="hlt">Al</span>/27Al)I of (1.7+/-1.3)×10-6. Three other relict CAIs and their host chondrules from the ungrouped carbonaceous chondrite Acfer 094, CH chondrite Acfer 182, and H3.4 ordinary chondrite Sharps do not have detectable 26Mg* [(<span class="hlt">26</span><span class="hlt">Al</span>/27Al)I<1×10-5, <(4-6)×10-6, and <1.3×10-5, respectively]. Isotopic data combined with mineralogical observations suggest that relict CAIs formed in an 16O-rich gaseous reservoir before their host chondrules, which originated in an 16O-poor gas. The Adelaide CAI was incorporated into its host chondrule after <span class="hlt">26</span><span class="hlt">Al</span> had mostly decayed, at least 2 Myr after the CAI formed, and this event reset <span class="hlt">26</span><span class="hlt">Al</span>-26Mg systematics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/888510','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/888510"><span id="translatedtitle">Bomb-Pulse Chlorine-36 at the Proposed Yucca Mountain Repository Horizon: An Investigation of Previous Conflicting Results and Collection of New Data</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Cizdziel, James</p> <p>2006-07-31</p> <p>Previous studies Los Alamos National Laboratory (LANL) found elevated ratios of chlorine-36 to total chloride (<span class="hlt">36</span><span class="hlt">Cl</span>/Cl) in samples of rock collected from the Exploratory Studies Facility (ESF) at Yucca Mountain (YM). The data were interpreted as an indication that fluids containing “bomb-pulse” <span class="hlt">36</span><span class="hlt">Cl</span> reached the repository horizon in the ~50 years since the peak period of above-ground nuclear testing. Due to the significance of <span class="hlt">36</span><span class="hlt">Cl</span> data to conceptual models of unsaturated zone flow, the United States Geological Survey (USGS) implemented a study to validate the LANL findings. The USGS drilled new boreholes at select locations across zones where bomb-pulse ratios had previously been identified. The drill cores were analyzed at Lawrence Livermore National Laboratory (LLNL). Because consensus was not reached between the USGS/LLNL and LANL on several fundamental points including the presence or absence of bomb-pulse <span class="hlt">36</span><span class="hlt">Cl</span>, an evaluation by the University of Nevada, Las Vegas (UNLV), was initiated. The overall objectives of the UNLV study were to investigate the source of the validation study’s conflicting results, and to obtain additional data on bomb-pulse isotopes at the repository horizon. UNLV engaged in discussions with previous investigators, reviewed reports, and analyzed archived samples. UNLV also collected new samples of rock from the ESF, soil profiles from the surface of YM, and samples of seep water from inside the ESF. Samples were analyzed for <span class="hlt">36</span><span class="hlt">Cl</span>/Cl ratios, and 99Tc and 129I in select samples. A column experiment was conducted mimicking the passage of bomb-pulse <span class="hlt">36</span><span class="hlt">Cl</span> through YM tuff. The work faced several obstacles including an extended shutdown of the tunnel. Only one sample yielded a background corrected <span class="hlt">36</span><span class="hlt">Cl</span>/Cl ratio that was higher than the accepted bomb-pulse threshold (1250 x 10-15). Specimen 01034214 obtained from the Drill Hole Wash fault (19+33) had a ratio of 1590 ± 80 (1σ) x10-15, whereas the other separate sample from this fault zone</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3557307','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3557307"><span id="translatedtitle">Excitation-induced exchange of Na+, K+, and Cl− in rat EDL muscle in vitro and in vivo: Physiology and pathophysiology</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p></p> <p>2013-01-01</p> <p>In skeletal muscle, excitation leads to increased [Na+]i, loss of K+, increased [K+]o, depolarization, and Cl− influx. This study quantifies these changes in rat extensor digitorum longus (EDL) muscles in vitro and in vivo using flame photometric determination of Na+ and K+ and <span class="hlt">36</span><span class="hlt">Cl</span> as a tracer for Cl−. In vitro, 5-Hz stimulation for 300 s increased intracellular Na+ content by 4.6 ± 1.2 µmol/g wet wt (P < 0.002) and decreased intracellular K+ content by 5.5 ± 2.3 µmol/g wet wt (P < 0.03). This would increase [K+]o by 28 ± 12 mM, sufficient to cause severe loss of excitability as the result of inactivation of Na+ channels. In rat EDL, in vivo stimulation at 5 Hz for 300 s or 60 Hz for 60 s induced significant loss of K+ (P < 0.01), sufficient to increase [K+]o by 71 ± 22 mM and 73 ± 15 mM, respectively. In spite of this, excitability may be maintained by the rapid and marked stimulation of the electrogenic Na+,K+ pumps already documented. This may require full utilization of the transport capacity of Na+,K+ pumps, which then becomes a limiting factor for physical performance. In buffer containing <span class="hlt">36</span><span class="hlt">Cl</span>, depolarization induced by increasing [K+]o to 40–80 mM augmented intracellular <span class="hlt">36</span><span class="hlt">Cl</span> by 120–399% (P < 0.001). Stimulation for 120–300 s at 5–20 Hz increased intracellular <span class="hlt">36</span><span class="hlt">Cl</span> by 100–188% (P < 0.001). In rats, Cl− transport in vivo was examined by injecting <span class="hlt">36</span><span class="hlt">Cl</span>, where electrical stimulation at 5 Hz for 300 s or 60 Hz for 60 s increased <span class="hlt">36</span><span class="hlt">Cl</span> uptake by 81% (P < 0.001) and 84% (P < 0.001), respectively, indicating excitation-induced depolarization. Cl− influx favors repolarization, improving K+ clearance and maintenance of excitability. In conclusion, excitation-induced fluxes of Na+, K+, and Cl− can be quantified in vivo, providing new evidence that in working muscles, extracellular accumulation of K+ is considerably higher than previously observed and the resulting depression of membrane excitability may be a major cause of muscle fatigue</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4321258','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4321258"><span id="translatedtitle">Short time interval for condensation of high-temperature silicates in the solar accretion disk</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Luu, Tu-Han; Young, Edward D.; Gounelle, Matthieu; Chaussidon, Marc</p> <p>2015-01-01</p> <p>Chondritic meteorites are made of primitive components that record the first steps of formation of solids in our Solar System. Chondrules are the major component of chondrites, yet little is known about their formation mechanisms and history within the solar protoplanetary disk (SPD). We use the reconstructed concentrations of short-lived <span class="hlt">26</span><span class="hlt">Al</span> in chondrules to constrain the timing of formation of their precursors in the SPD. High-precision bulk magnesium isotopic measurements of 14 chondrules from the Allende chondrite define a <span class="hlt">26</span><span class="hlt">Al</span> isochron with <span class="hlt">26</span><span class="hlt">Al</span>/27Al = 1.2(±0.2) × 10−5 for this subset of Allende chondrules. This can be considered to be the minimum bulk chondrule <span class="hlt">26</span><span class="hlt">Al</span> isochron because all chondrules analyzed so far with high precision (∼50 chondrules from CV and ordinary chondrites) have an inferred minimum bulk initial (<span class="hlt">26</span><span class="hlt">Al</span>/27Al) ≥ 1.2 × 10−5. In addition, mineral <span class="hlt">26</span><span class="hlt">Al</span> isochrons determined on the same chondrules show that their formation (i.e., fusion of their precursors by energetic events) took place from 0 Myr to ∼2 Myr after the formation of their precursors, thus showing in some cases a clear decoupling in time between the two events. The finding of a minimum bulk chondrule <span class="hlt">26</span><span class="hlt">Al</span> isochron is used to constrain the astrophysical settings for chondrule formation. Either the temperature of the condensation zone dropped below the condensation temperature of chondrule precursors at ∼1.5 My after the start of the Solar System or the transport of precursors from the condensation zone to potential storage sites stopped after 1.5 My, possibly due to a drop in the disk accretion rate. PMID:25605942</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25605942','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25605942"><span id="translatedtitle">Short time interval for condensation of high-temperature silicates in the solar accretion disk.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Luu, Tu-Han; Young, Edward D; Gounelle, Matthieu; Chaussidon, Marc</p> <p>2015-02-01</p> <p>Chondritic meteorites are made of primitive components that record the first steps of formation of solids in our Solar System. Chondrules are the major component of chondrites, yet little is known about their formation mechanisms and history within the solar protoplanetary disk (SPD). We use the reconstructed concentrations of short-lived (<span class="hlt">26</span>)<span class="hlt">Al</span> in chondrules to constrain the timing of formation of their precursors in the SPD. High-precision bulk magnesium isotopic measurements of 14 chondrules from the Allende chondrite define a (<span class="hlt">26</span>)<span class="hlt">Al</span> isochron with (<span class="hlt">26</span>)<span class="hlt">Al</span>/(27)Al = 1.2(±0.2) × 10(-5) for this subset of Allende chondrules. This can be considered to be the minimum bulk chondrule (<span class="hlt">26</span>)<span class="hlt">Al</span> isochron because all chondrules analyzed so far with high precision (∼50 chondrules from CV and ordinary chondrites) have an inferred minimum bulk initial ((<span class="hlt">26</span>)<span class="hlt">Al</span>/(27)Al) ≥ 1.2 × 10(-5). In addition, mineral (<span class="hlt">26</span>)<span class="hlt">Al</span> isochrons determined on the same chondrules show that their formation (i.e., fusion of their precursors by energetic events) took place from 0 Myr to ∼2 Myr after the formation of their precursors, thus showing in some cases a clear decoupling in time between the two events. The finding of a minimum bulk chondrule (<span class="hlt">26</span>)<span class="hlt">Al</span> isochron is used to constrain the astrophysical settings for chondrule formation. Either the temperature of the condensation zone dropped below the condensation temperature of chondrule precursors at ∼1.5 My after the start of the Solar System or the transport of precursors from the condensation zone to potential storage sites stopped after 1.5 My, possibly due to a drop in the disk accretion rate.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014cosp...40E3444U','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014cosp...40E3444U"><span id="translatedtitle">Extreme event of cosmic rays in 775 AD: Data and hypotheses</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Usoskin, Ilya; Kovaltsov, Gennady</p> <p></p> <p>An interesting event has been found recently that took place around 775 AD, as a peak in cosmogenic radionuclides: 14C, 10Be, and <span class="hlt">36</span><span class="hlt">Cl</span>. Detailed analysis of annual 14C data measured in several different tree trunks (from Japan and Europe) as well as in shallow sea coral skeletons is confirmed by lower resolution data of 10Be and <span class="hlt">36</span><span class="hlt">Cl</span> in polar ice cores. While the very existence of the event is beyond any doubts, its origin is not clear. We overview different hypotheses proposed as a cause of the event, including a gamma-ray burst, supernova, cometary impact and extreme solar flare. We discuss several errors made earlier in evaluating parameters of the event and the corresponding phenomena. We show that an extreme event in solar energetic particles remains the most probable reason for the event.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22424840','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22424840"><span id="translatedtitle">Feasibility study of activity measurement of positron emitters based on gamma-gamma coincident detection by two NaI(Tl) detectors.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Volkovitsky, Peter; Unterweger, Michael</p> <p>2012-09-01</p> <p>Detection of two and more γ-rays in coincidence by two NaI(Tl) detectors with almost 4π geometry allows absolute characterization of radionuclides emitting coincidence gammas. The method is a generalization of the Eldridge-Crowther method developed originally for x-rays and low energy γ-rays. This method is applied to the case of (94)Nb decay with two coincident gamma-rays emitted in one cascade. The application of this method for the case of coincident positron-gamma emission ((22)Na and (<span class="hlt">26</span>)<span class="hlt">Al</span> sources) meets some difficulties. In these decays, two 511 keV gamma quanta produced in positron annihilation are strongly correlated. Despite the fact that the third gamma emitted in (22)Na and (<span class="hlt">26</span>)<span class="hlt">Al</span> decays is not correlated with two annihilation quanta, the number of independent observables for (22)Na and (<span class="hlt">26</span>)<span class="hlt">Al</span> decays is less than the number of unknowns. The small parameter ω(00), the probability that both annihilation quanta escape detection in both NaI(Tl) detectors, cannot be determined. However, if this parameter is defined from experimental data for one source with known activity ((22)Na), the activity of the other source ((<span class="hlt">26</span>)<span class="hlt">Al</span>) can be calculated from experimental data for (<span class="hlt">26</span>)<span class="hlt">Al</span> decay.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6168944','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6168944"><span id="translatedtitle">Characterization of GABA/sub A/ receptor-mediated /sup 36/chloride uptake in rat brain synaptoneurosomes</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Luu, M.D.; Morrow, A.L.; Paul, S.M.; Schwartz, R.D.</p> <p>1987-09-07</p> <p>..gamma..-Aminobutyric acid (GABA) receptor-mediated /sup 36/chloride (/sup <span class="hlt">36</span>/<span class="hlt">Cl</span>/sup -/) uptake was measured in synaptoneurosomes from rat brain. GABA and GABA agonists stimulated /sup <span class="hlt">36</span>/<span class="hlt">Cl</span>/sup -/ uptake in a concentration-dependent manner with the following order of potency: Muscimol>GABA>piperidine-4-sulfonic acid (P4S)>4,5,6,7-tetrahydroisoxazolo-(5,4-c)pyridin-3-ol (THIP)=3-aminopropanesulfonic acid (3APS)>>taurine. Both P4S and 3APS behaved as partial agonists, while the GABA/sub B/ agonist, baclofen, was ineffective. The response to muscimol was inhibited by bicuculline and picrotoxin in a mixed competitive/non-competitive manner. Other inhibitors of GABA receptor-opened channels or non-neuronal anion channels such as penicillin, picrate, furosemide and disulfonic acid stilbenes also inhibited the response to muscimol. A regional variation in muscimol-stimulated /sup <span class="hlt">36</span>/<span class="hlt">Cl</span>/sup -/ uptake was observed; the largest responses were observed in the cerebral cortex, cerebellum and hippocampus, moderate responses were obtained in the striatum and hypothalamus and the smallest response was observed in the pons-medulla. GABA receptor-mediated /sup <span class="hlt">36</span>/<span class="hlt">Cl</span>/sup -/ uptake was also dependent on the anion present in the media. The muscinol response varied in media containing the following anions: Br/sup -/>Cl/sup -/greater than or equal toNO/sub 3//sup -/>I/sup -/greater than or equal toSCN/sup -/>>C/sub 3/H/sub 5/OO/sup -/greater than or equal toClO/sub 4//sup -/>F/sup -/, consistent with the relative anion permeability through GABA receptor-gated anion channels and the enhancement of convulsant binding to the GABA receptor-gated Cl/sup -/ channel. 43 references, 4 figures, 3 tables.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002AGUFM.H11F..04M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002AGUFM.H11F..04M"><span id="translatedtitle">Quantifying Salinization of the Upper-Middle Rio Grande Using a Basin-Scale Water and Chloride Mass Balance Model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mills, S. K.; Phillips, F. M.; Hogan, J. F.; Hendrickx, J. M.</p> <p>2002-12-01</p> <p>The Rio Grande is clearly undergoing salinization, manifested by a 50-fold increase in total dissolved solids content between its headwaters in Colorado and the U.S.-Mexico border. To elucidate the causes of this salinization, we conducted an eight-day synoptic sampling campaign in August 2001. This sampling included the river, its major tributaries, and major irrigation drain inflows. Along 1200 km between the river headwaters in Colorado and Fort Quitman, Texas, we collected 110 water samples with an average interval of ~10 km between sampling locales. In the laboratory, samples were analyzed for major constituents including chloride, as well as for bromide and the <span class="hlt">36</span><span class="hlt">Cl</span>/Cl ratio. Isotopic fingerprinting using the <span class="hlt">36</span><span class="hlt">Cl</span>/Cl ratio indicates that meteoric waters and deep sedimentary brines respectively account for most of the water and most of the salt inflow to the Rio Grande. The meteoric end member has a <span class="hlt">36</span><span class="hlt">Cl</span>/Cl ratio of 1100 and a Cl/Br ratio of 30; the brine end member has a <span class="hlt">36</span><span class="hlt">Cl</span>/Cl ratio of 35 and a Cl/Br ratio of 1150. Using these end member chemistries with USGS stream flow gauging data, we constructed a water- and salt- instantaneous mass balance model of the Rio Grande for the eight-day sampling interval. This model indicates that most water losses from the Rio Grande are due to evaporation from Elephant Butte reservoir, open water evaporation from irrigation ditches, and evapotranspiration of riparian and ditch-bank vegetation. The model also emphasizes the significance of salt input due to deep brine discharge to the river, particularly at the downstream ends of local sedimentary basins of the Rio Grande rift. The Rio Grande receives a smaller amount of salt from saline drains near El Paso, which may be acquiring salt from deep brine discharge as they cross over faults or other structural fluid conduits.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70073667','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70073667"><span id="translatedtitle">Flow-path textures and mineralogy in tuffs of the unsaturated zone</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Levy, Schön; Chipera, Steve; WoldeGabriel, Giday; Fabryka-Martin, June; Roach, Jeffrey; Sweetkind, Donald S.; Haneberg, William C.; Mozley, Peter S.; Moore, J. Casey; Goodwin, Laurel B.</p> <p>1999-01-01</p> <p>The high concentration of chlorine-36 (<span class="hlt">36</span><span class="hlt">Cl</span>) produced by above-ground nuclear tests (bomb-pulse) provides a fortuitous tracer for infiltration during the last 50 years, and is used to detect fast flow in the unsaturated zone at Yucca Mountain, Nevada, a thick deposit of welded and nonwelded tuffs. Evidence of fast flow as much as 300 m into the mountain has been found in several zones in a 7.7-km tunnel. Many zones are associated with faults that provide continuous fracture flow paths from the surface. In the Sundance fault zone, water with the bomb-pulse signature has moved into subsidiary fractures and breccia zones. We found no highly distinctive mineralogic associations of fault and fracture samples containing bomb-pulse <span class="hlt">36</span><span class="hlt">Cl</span>. Bomb-pulse sites are slightly more likely to have calcite deposits than are non-bomb-pulse sites. Most other mineralogic and textural associations of fast-flow paths reflect the structural processes leading to locally enhanced permeability rather than the effects of ground-water percolation. Water movement through the rock was investigated by isotopic analysis of paired samples representing breccia zones and fractured wall rock bounding the breccia zones. Where bomb-pulse <span class="hlt">36</span><span class="hlt">Cl</span> is present, the waters in bounding fractures and intergranular pores of the fast pathways are not in equilibrium with respect to the isotopic signal. In structural domains that have experienced extensional deformation, fluid flow within a breccia is equivalent to matrix flow in a particulate rock, whereas true fracture flow occurs along the boundaries of a breccia zone. Where shearing predominated over extension, the boundary between wall rock and breccia is rough and irregular with a tight wallrock/breccia contact. The absence of a gap between the breccia and the wall rock helps maintain fluid flow within the breccia instead of along the wallrock/breccia boundary, leading to higher <span class="hlt">36</span><span class="hlt">Cl</span>/Cl values in the breccia than in the wall rock.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/7441192','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/7441192"><span id="translatedtitle">A single-cell technique for the measurement of membrane potential, membrane conductance, and the efflux of rapidly penetrating solutes in Amphiuma erythrocytes.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Stoner, L C; Kregenow, F M</p> <p>1980-10-01</p> <p>We describe a single-cell technique for measuring membrane potential, membrane resistance, and the efflux of rapidly penetrating solutes such as Cl and H2O. Erythrocytes from Amphiuma means were aspirated into a Sylgard (Dow Corning Corp.)-coated capillary. The aspirated cell separated a solution within the capillary from a solution in the bath. Each of these two solutions was contiguous with approximately 5% of the total membrane surface. Microelectrodes placed concentrically within the capillary permit the measurement of intracellular voltage, specific membrane resistance, and the electrical seal between the two solutions. The intracellular voltage averaged -17.7 mV (pH 7.6) and changed as either intra- or extracellular chloride was varied. The average specific membrane resistance measured by passing current across the exposed membrane surface was 110 ohm-cm2. <span class="hlt">36</span><span class="hlt">Cl</span> and tritiated H2O fluxes (0.84 +/- 0.05 x 10(-6) M . cm-2 . min-1 and 6.4 +/- 1.5 x 10(-3) M . cm-2 . min-1, respectively) were determined by noting the rate at which isotope leaves the cell and crosses the membrane exposed to the bath. Our measured values for the flux of <span class="hlt">36</span><span class="hlt">Cl</span> and tritiated H2O approximate reported values for free-floating cells. <span class="hlt">36</span><span class="hlt">Cl</span> efflux, in addition, is inhibited by 4-acetamido-4'-isothiocyano-stilbene 2,2'-disulfonic acid (SITS) and furosemide, known inhibitors of the anion exchange mechanism responsible for the rapid anion fluxes of red blood cells. One can also demonstrate directly that > 89% of <span class="hlt">36</span><span class="hlt">Cl</span> efflux is "electrically silent" by analyzing the flux in the presence of an imposed transcellular voltage.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1067084','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1067084"><span id="translatedtitle">Nitrate Uptake into Barley (Hordeum vulgare) Plants 1</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Deane-Drummond, Celia E.; Glass, Anthony D. M.</p> <p>1982-01-01</p> <p>Evidence is presented that chlorate is an extremely good analog for nitrate during nitrate uptake by intact barley (Hordeum vulgare cv. Fergus) roots. The depletion of ClO3− or NO3− from uptake media over 2 to 6 hours by seedlings was found to be dependent on combined NO3− plus ClO3− concentrations, and total anion uptake was equivalent at different NO3−/ClO3− ratios. After loading barley seedlings with <span class="hlt">36</span><span class="hlt">Cl</span>O3− for 6 hours, kinetic parameters were derived from the analysis of efflux of [<span class="hlt">36</span><span class="hlt">Cl</span>] chlorate into unlabeled solution. On the basis of this analysis, the half times for exchange for the cytoplasmic and vacuolar phases were 17 minutes and 20 hours, respectively. Data pooled from a number of different experiments were used to calculate kinetic constants (Km and Vmax) for <span class="hlt">36</span><span class="hlt">Cl</span>O3− influx into barley roots at different external ClO3−/NO3− ratios, using short (10 minutes) influx times. There appeared to be no discrimination by the root cells between ClO3− and NO3−. Lineweaver-Burk analysis of the interaction between nitrate and chlorate were characteristic of competitive inhibition at low nitrate concentrations (0-0.5 mm). At higher concentrations, in the range of >1 mm, similar interactions between these ions were evident. PMID:16662478</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2000GMS...122..349W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000GMS...122..349W"><span id="translatedtitle">Use of chlorine-36 data to evaluate fracture flow and transport models at Yucca Mountain, Nevada</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wolfsberg, Andrew; Campbell, Katherine; Fabryka-Martin, June</p> <p></p> <p>An extensive set of <span class="hlt">36</span><span class="hlt">Cl</span> data has been collected in the Exploratory Studies Facility (ESF), an 8 km long tunnel at Yucca Mountain, Nevada, for the purpose of developing and testing conceptual models of flow and transport at this site. These data have been used in conjunction with a numerical model to establish upper and lower bounds on infiltration rates, estimate groundwater ages, evaluate hydrologic parameters for fractured volcanic tuff, and develop a conceptual model for the distribution of fast flow paths. At several locations, the measured signals are high enough to be unambiguous indicators of at least a small component of bomb-pulse <span class="hlt">36</span><span class="hlt">Cl</span> fallout from atmospheric testing of nuclear devices in the 1950s and 1960s, implying that some fraction of the water traveled from the ground surface to the level of the ESF during the last 50 years. Characterization of the structural settings of these samples as well as predictive modeling generally support the conceptual model that a through-cutting fault in conjunction with sufficient infiltration would be required to transmit bomb-pulse <span class="hlt">36</span><span class="hlt">Cl</span> to the sample depth in less than 50 years. Away from such fault zones, the ages of water samples at the ESF appear to be significantly controlled by the thickness of the nonwelded tuff between the ground surface and the ESF.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5876125','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5876125"><span id="translatedtitle">Altered chloride metabolism in cultured cystic fibrosis skin fibroblasts</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Mattes, P.M.; Maloney, P.C.; Littlefield, J.W.</p> <p>1987-05-01</p> <p>An abnormal regulation of chloride permeability has been described for epithelial cells from patients with cystic fibrosis (CF). To learn more about the biochemical basis of this inherited disease, the authors have studied chloride metabolism in cultured CF fibroblasts by comparing the efflux of /sup <span class="hlt">36</span>/<span class="hlt">Cl</span>/sup -/ from matched pairs of CF and normal fibroblasts. The rate constants describing /sup <span class="hlt">36</span>/<span class="hlt">Cl</span>/sup -/ efflux did not differ between the two cell types, but in each of the four pairs tested the amount of /sup <span class="hlt">36</span>/<span class="hlt">Cl</span>/sup -/ contained within CF cells was consistently reduced, by 25-30%, relative to normal cells. Comparisons of cell water content and /sup 22/Na/sup +/ efflux showed no differences between the two cell types, suggesting that overall intracellular chloride concentration is lower than normal in CF fibroblasts. Such data suggest that the CF gene defect is expressed in skin fibroblasts and that this defect may alter the regulation of intracellular Cl/sup -/ concentration, perhaps through changes in Cl/sup -/ permeability.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/7024378','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/7024378"><span id="translatedtitle">Chlorine-36 tracing of salinity sources in the dry valleys of Victoria land, Antarctica</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Carlson, C.A.; Phillips, F.M. ); Elmore, D. ); Bentley, H.W. )</p> <p>1990-02-01</p> <p>Chlorine-36 was used to trace the origins of salts in six saline lakes in the Dry Valleys of Southern Victoria Land, Antarctica. Characteristic {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> signatures were estimated for the various potential chloride sources, which include atmospheric deposition, rock weathering, seawater, and deep ground water. {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>/Cl ratios were measured in natural waters and salts from the Dry Valleys. Dilute lake waters (Cl{sup {minus}} < 100 mg/l) were found to have {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>/Cl ratios in the range 100 {times} 10{sup {minus}15} to 1,700 {times} 10{sup {minus}15}, whereas saline waters (Cl{sup {minus}} > 1000 mg/l) had ratios in the range 9 {times} 10{sup {minus}15} to 40 {times} 10{sup {minus}15}. Simple mixing models were employed to quantify the relative contributions of the various chloride sources to Lake Vanda and Don Juan Pond. These results show that Lake Vanda has received its chloride from both deep ground water and the Onyx River. Don Juan Pond has received nearly all its chloride from deep ground water, probably ultimately from rock-water interaction. Deep ground water is the principal sources of chloride to the lakes of Wright Valley. However, preliminary data suggest that marine-derived salts or relict sea water may be a significant sources of chloride to the lakes of Taylor Valley, implying a possible recent marine invasion that did not affect Wright Valley.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1990GeCoA..54..311C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1990GeCoA..54..311C"><span id="translatedtitle">Chlorine-36 tracing of salinity sources in the Dry Valleys of Victoria Land, Antarctica</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Carlson, Catherine A.; Phillips, Fred M.; Elmore, David; Bentley, Harold W.</p> <p>1990-02-01</p> <p>Chlorine-36 was used to trace the origins of salts in six saline lakes in the Dry Valleys of Southern Victoria Land, Antarctica. Characteristic <span class="hlt">36</span><span class="hlt">Cl</span> signatures were estimated for the various potential chloride sources, which include atmospheric deposition, rock weathering, seawater, and deep ground water. <span class="hlt">36</span><span class="hlt">Cl</span> /Cl ratios were measured in natural waters and salts from the Dry Valleys. Dilute lake waters (Cl - < 100 mg/l) were found to have <span class="hlt">36</span><span class="hlt">Cl</span> /Cl ratios in the range 100 × 10 -15 to 1,700 × 10 -15, whereas saline waters (Cl - > 1000 mg/l) had ratios in the range 9 × 10 -15 to 40 × 10 -15. Simple mixing models were employed to quantify the relative contributions of the various chloride sources to Lake Vanda and Don Juan Pond. These results show that Lake Vanda has received its chloride from both deep ground water and the Onyx River. Don Juan Pond has received nearly all its chloride from deep ground water, probably ultimately from rock-water interaction. Deep ground water is the principal source of chloride to the lakes of Wright Valley. However, preliminary data suggest that marine-derived salts or relict sea water may be a significant source of chloride to the lakes of Taylor Valley, implying a possible recent marine invasion that did not affect Wright Valley.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16716463','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16716463"><span id="translatedtitle">A comparison of the soil migration and plant uptake of radioactive chlorine and iodine from contaminated groundwater.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ashworth, D J; Shaw, G</p> <p>2006-01-01</p> <p>A 6-month soil column experiment was conducted to compare the upward migration and plant uptake of radiochlorine and radioiodine from shallow, near-surface contaminated water tables. Both fixed and fluctuating water tables were studied. After 6 months, (<span class="hlt">36</span>)<span class="hlt">Cl</span> activity concentrations were relatively uniform throughout the soil profile apart from an accumulation at the soil surface, which was especially marked under a fluctuating water table scenario. In contrast, (125)I (a surrogate for (129)I) tended to accumulate at the boundary between the anoxic conditions at the base of the column and the oxic conditions above, due to its redox-dependent sorption behaviour. The uptake of (<span class="hlt">36</span>)<span class="hlt">Cl</span> by perennial ryegrass was much greater than that of (125)I due to its greater migration into the rooting zone and its ready availability in soil solution. In the context of radioactive waste disposal, where these radionuclides may potentially be released into groundwater, (<span class="hlt">36</span>)<span class="hlt">Cl</span> would be expected to present a greater potential for contamination of the biosphere than (129)I.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/7175489','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/7175489"><span id="translatedtitle">Volume-induced increase of anion permeability in human lymphocytes.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Grinstein, S; Clarke, C A; Dupre, A; Rothstein, A</p> <p>1982-12-01</p> <p>Peripheral blood mononuclear cells (PBM) readjust their volumes after swelling in hypotonic media. This regulatory volume decrease (RVD) is associated with a loss of cellular K+ and is thought to be promoted by an increased permeability to this ion. In contrast, no change in volume was observed when K+ permeability of PBM in isotonic media was increased to comparable or higher levels using valinomycin. Moreover, valinomycin-induced 86Rb+ loss in K+-free medium was considerably slower than in K+-rich medium. These results suggest that anion conductance limits net salt loss in isotonic media. Direct measurements of relative conductance confirmed that in volume-static cells, anion conductance is lower than that of K+. In volume-regulating cells depolarization occurred presumably as a result of increased anion conductance. Accordingly, the efflux of <span class="hlt">36</span><span class="hlt">Cl</span> from PBM was markedly increased by hypotonic stress. Since both membrane potential and intracellular <span class="hlt">36</span><span class="hlt">Cl</span> concentration are reduced in hypotonically swollen cells, the increased efflux is probably due to a change in Cl- permeability. Anions and cations seem to move independently through the volume-induced pathways: the initial rate of 86Rb uptake in swollen cells was not affected by replacement of external Cl- by SO=4; conversely, <span class="hlt">36</span><span class="hlt">Cl</span> fluxes were unaffected by substitution of K+ by Na+. The data indicate that anion conductance is rate-determining in salt and water loss from PBM. An increase in anion conductance is suggested to be the critical step of RVD of human PBM.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/2139343','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/2139343"><span id="translatedtitle">A Cl(-)-translocating adenosinetriphosphatase in Acetabularia acetabulum. 2. Reconstitution of the enzyme into liposomes and effect of net charges of liposomes on chloride permeability and reconstitution.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ikeda, M; Oesterhelt, D</p> <p>1990-02-27</p> <p>The Mono Q-III fraction, a Mg2(+)-ATPase, isolated from Acetabularia acetabulum was reconstituted into liposomes of various net charges prepared by the reversed-phase method and tested for a Cl(-)-translocating activity. The liposomes from a mixture of egg lecithin, dicetyl phosphate, and cholesterol (63:18:9 mole ratio, negative liposomes) and from a mixture of egg lecithin and cholesterol (63:9 mole ratio, neutral liposomes) were less leaky than positive liposomes from asolectin, and from a mixture of egg lecithin, stearylamine, and cholesterol (63:18:9 mole ratio). A significant increase in <span class="hlt">36</span><span class="hlt">Cl</span>- efflux from the negative and neutral liposomes was observed by addition of ATP in the presence of valinomycin after incorporation of the enzyme by short-term dialysis. The ATP-driven <span class="hlt">36</span><span class="hlt">Cl</span>- efflux was inhibited by addition of azide, an inhibitor of the ATPase. The preincubation of the enzyme with phenylglyoxal, an arginine-modifying reagent, inactivated ATP-mediated <span class="hlt">36</span><span class="hlt">Cl</span>- efflux, but the ATPase activity of the preparation was not affected. When chloride was replaced by 35SO4(2)-, no ATP-dependent 35SO4(2)- efflux was detectable from the proteoliposomes. Proton-translocating activity of the enzyme was also tested, and no fluorescent quenching of 9-ACMA was observed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2008SSCom.145...15F&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2008SSCom.145...15F&link_type=ABSTRACT"><span id="translatedtitle">Large magnetic entropy change of Gd-based ternary bulk metallic glass in liquid-nitrogen temperature range</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fu, H.; Zhang, X. Y.; Yu, H. J.; Teng, B. H.; Zu, X. T.</p> <p>2008-01-01</p> <p>Gd 60Co <span class="hlt">26</span><span class="hlt">Al</span> 14 bulk metallic glass (BMG) with a diameter of 3 mm was prepared by arc-melting and copper-mold suck-casting. X-ray diffraction (XRD) results show that the as-cast Gd 60Co <span class="hlt">26</span><span class="hlt">Al</span> 14 rod consists of a wholly amorphous phase. Differential scanning calorimetry (DSC) measurements indicated that one glass transition temperature (Tg) and two crystallization temperatures (TX) occur at 570, 602, and 642 K, respectively. Moreover, two Curie temperatures of 82 and 128 K, which correspond to the two amorphous phases in the DSC trace, were determined from the thermo-magnetization curve. The maximal magnetic entropy change (ΔSM) under 0-5 T is about 10.1 J/kg K at 75 K and the refrigerant capacity (RC) is about 556 J/kg, which makes Gd 60Co <span class="hlt">26</span><span class="hlt">Al</span> 14 BMG a promising candidate for magnetic refrigerant near liquid-nitrogen temperatures.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_20 --> <div id="page_21" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="401"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4776524','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4776524"><span id="translatedtitle">Isotopic evidence for primordial molecular cloud material in metal-rich carbonaceous chondrites</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Van Kooten, Elishevah M. M. E.; Wielandt, Daniel; Schiller, Martin; Nagashima, Kazuhide; Thomen, Aurélien; Olsen, Mia B.; Nordlund, Åke; Krot, Alexander N.; Bizzarro, Martin</p> <p>2016-01-01</p> <p>The short-lived <span class="hlt">26</span><span class="hlt">Al</span> radionuclide is thought to have been admixed into the initially <span class="hlt">26</span><span class="hlt">Al</span>-poor protosolar molecular cloud before or contemporaneously with its collapse. Bulk inner Solar System reservoirs record positively correlated variability in mass-independent 54Cr and 26Mg*, the decay product of <span class="hlt">26</span><span class="hlt">Al</span>. This correlation is interpreted as reflecting progressive thermal processing of in-falling <span class="hlt">26</span><span class="hlt">Al</span>-rich molecular cloud material in the inner Solar System. The thermally unprocessed molecular cloud matter reflecting the nucleosynthetic makeup of the molecular cloud before the last addition of stellar-derived <span class="hlt">26</span><span class="hlt">Al</span> has not been identified yet but may be preserved in planetesimals that accreted in the outer Solar System. We show that metal-rich carbonaceous chondrites and their components have a unique isotopic signature extending from an inner Solar System composition toward a 26Mg*-depleted and 54Cr-enriched component. This composition is consistent with that expected for thermally unprocessed primordial molecular cloud material before its pollution by stellar-derived <span class="hlt">26</span><span class="hlt">Al</span>. The 26Mg* and 54Cr compositions of bulk metal-rich chondrites require significant amounts (25–50%) of primordial molecular cloud matter in their precursor material. Given that such high fractions of primordial molecular cloud material are expected to survive only in the outer Solar System, we infer that, similarly to cometary bodies, metal-rich carbonaceous chondrites are samples of planetesimals that accreted beyond the orbits of the gas giants. The lack of evidence for this material in other chondrite groups requires isolation from the outer Solar System, possibly by the opening of disk gaps from the early formation of gas giants. PMID:26858438</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26858438','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26858438"><span id="translatedtitle">Isotopic evidence for primordial molecular cloud material in metal-rich carbonaceous chondrites.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Van Kooten, Elishevah M M E; Wielandt, Daniel; Schiller, Martin; Nagashima, Kazuhide; Thomen, Aurélien; Larsen, Kirsten K; Olsen, Mia B; Nordlund, Åke; Krot, Alexander N; Bizzarro, Martin</p> <p>2016-02-23</p> <p>The short-lived (<span class="hlt">26</span>)<span class="hlt">Al</span> radionuclide is thought to have been admixed into the initially (<span class="hlt">26</span>)<span class="hlt">Al</span>-poor protosolar molecular cloud before or contemporaneously with its collapse. Bulk inner Solar System reservoirs record positively correlated variability in mass-independent (54)Cr and (26)Mg*, the decay product of (<span class="hlt">26</span>)<span class="hlt">Al</span>. This correlation is interpreted as reflecting progressive thermal processing of in-falling (<span class="hlt">26</span>)<span class="hlt">Al</span>-rich molecular cloud material in the inner Solar System. The thermally unprocessed molecular cloud matter reflecting the nucleosynthetic makeup of the molecular cloud before the last addition of stellar-derived (<span class="hlt">26</span>)<span class="hlt">Al</span> has not been identified yet but may be preserved in planetesimals that accreted in the outer Solar System. We show that metal-rich carbonaceous chondrites and their components have a unique isotopic signature extending from an inner Solar System composition toward a (26)Mg*-depleted and (54)Cr-enriched component. This composition is consistent with that expected for thermally unprocessed primordial molecular cloud material before its pollution by stellar-derived (<span class="hlt">26</span>)<span class="hlt">Al</span>. The (26)Mg* and (54)Cr compositions of bulk metal-rich chondrites require significant amounts (25-50%) of primordial molecular cloud matter in their precursor material. Given that such high fractions of primordial molecular cloud material are expected to survive only in the outer Solar System, we infer that, similarly to cometary bodies, metal-rich carbonaceous chondrites are samples of planetesimals that accreted beyond the orbits of the gas giants. The lack of evidence for this material in other chondrite groups requires isolation from the outer Solar System, possibly by the opening of disk gaps from the early formation of gas giants.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.5679A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.5679A"><span id="translatedtitle">Isochron-burial dating of glacially-driven sediments: first results from the Alps</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Akçar, Naki; Ivy-Ochs, Susan; Alfimov, Vasily; Claude, Anne; Reber, Regina; Christl, Marcus; Vockenhuber, Christof; Schlunegger, Fritz; Dehnert, Andreas; Rahn, Meinert; Schlüchter, Christian</p> <p>2016-04-01</p> <p>The recently introduced method of isochron-burial dating, employs the fact that the samples from a well-defined single bed in a deposit would have the same post-burial but different pre-burial histories. The analysis of cosmogenic 10Be and <span class="hlt">26</span><span class="hlt">Al</span> in such samples enables the modeling of the post-burial component and the determination of the <span class="hlt">26</span><span class="hlt">Al</span>/10Be at the time of burial. The isochron-burial age can then be calculated from the initial and the measured ratios. In this study, we focus on the isochron-burial dating of the oldest Quaternary deposits of the Alpine Foreland. These are called Swiss Deckenschotter (cover gravels) as they build mesa-type hill tops on the Mesozoic or Cenozoic bedrock of the Swiss Alpine forelands. Deckenschotter consists of glaciofluvial gravel layers intercalated with glacial and/or overbank deposits. Although previously morphostratigraphically correlated with Günz and Mindel glaciations of Penck and Brückner, the Swiss Deckenschotter is likely much older, and their chronostratigraphy is not well constrained. In order to reconstruct the chronology of these deposits, we collected more than 30 clasts of different lithology, shape and size from a single stratigraphic horizon in an abandoned gravel pit in Siglistorf (canton Zurich). We processed 19 clasts for cosmogenic 10Be and <span class="hlt">26</span><span class="hlt">Al</span>. Four samples did not yield successful <span class="hlt">26</span><span class="hlt">Al</span> measurements and two were unsuccessful for 10Be. Most of the samples have low nuclide concentrations, i.e. <20000 10Be at/g and <150000 <span class="hlt">26</span><span class="hlt">Al</span> at/g. Finally, using the <span class="hlt">26</span><span class="hlt">Al</span>/10Be ratio of the samples we calculated an isochron-burial age of around 1.5 Ma. Our results from this study indicate that glaciofluvial sediments can well be time-calibrated with isochron-burial dating despite the low cosmogenic nuclide concentrations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015NIMPB.361..281J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015NIMPB.361..281J"><span id="translatedtitle">The use of aluminum nitride to improve Aluminum-26 Accelerator Mass Spectrometry measurements and production of Radioactive Ion Beams</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Janzen, Meghan S.; Galindo-Uribarri, Alfredo; Liu, Yuan; Mills, Gerald D.; Romero-Romero, Elisa; Stracener, Daniel W.</p> <p>2015-10-01</p> <p>We present results and discuss the use of aluminum nitride as a promising source material for Accelerator Mass Spectrometry (AMS) and Radioactive Ion Beams (RIBs) science applications of <span class="hlt">26</span><span class="hlt">Al</span> isotopes. The measurement of <span class="hlt">26</span><span class="hlt">Al</span> in geological samples by AMS is typically conducted on Al2O3 targets. However, Al2O3 is not an ideal source material because it does not form a prolific beam of Al- required for measuring low-levels of <span class="hlt">26</span><span class="hlt">Al</span>. Multiple samples of aluminum oxide (Al2O3), aluminum nitride (AlN), mixed Al2O3-AlN as well as aluminum fluoride (AlF3) were tested and compared using the ion source test facility and the stable ion beam (SIB) injector platform at the 25-MV tandem electrostatic accelerator at Oak Ridge National Laboratory. Negative ion currents of atomic and molecular aluminum were examined for each source material. It was found that pure AlN targets produced substantially higher beam currents than the other materials and that there was some dependence on the exposure of AlN to air. The applicability of using AlN as a source material for geological samples was explored by preparing quartz samples as Al2O3 and converting them to AlN using a carbothermal reduction technique, which involved reducing the Al2O3 with graphite powder at 1600 °C within a nitrogen atmosphere. The quartz material was successfully converted to AlN. Thus far, AlN proves to be a promising source material and could lead towards increasing the sensitivity of low-level <span class="hlt">26</span><span class="hlt">Al</span> AMS measurements. The potential of using AlN as a source material for nuclear physics is also very promising by placing <span class="hlt">26</span><span class="hlt">Al</span>N directly into a source to produce more intense radioactive beams of <span class="hlt">26</span><span class="hlt">Al</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/894307','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/894307"><span id="translatedtitle">Bomb-Pulse Chlorine-36 At The Proposed Yucca Mountain Repository Horizon: An Investigation Of Previous Conflicting Results And Collection Of New Data</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>J. Cizdziel</p> <p>2006-07-28</p> <p>Previous studies by scientists at Los Alamos National Laboratory (LANL) found elevated ratios of chlorine-36 to total chloride ({sup <span class="hlt">36</span>}<span class="hlt">Cl</span>/Cl) in samples of rock collected from the Exploratory Studies Facility (ESF) and the Enhanced Characterization of the Repository Block (ECRB) at Yucca Mountain as the tunnels were excavated. The data were interpreted as an indication that fluids containing 'bomb-pulse' {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> reached the repository horizon in the {approx}50 years since the peak period of above-ground nuclear testing. Moreover, the data support the concept that so-called fast pathways for infiltration not only exist but are active, possibly through a combination of porous media, faults and/or other geologic features. Due to the significance of {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> data to conceptual models of unsaturated zone flow and transport, the United States Geological Survey (USGS) was requested by the Department of Energy (DOE) to design and implement a study to validate the LANL findings. The USGS chose to drill new boreholes at select locations across zones where bomb-pulse ratios had previously been identified. The drill cores were analyzed at Lawrence Livermore National Laboratory (LLNL) for {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>/Cl using both active and passive leaches, with the USGS/LLNL concluding that the active leach extracted too much rock-Cl and the passive leach did not show bomb-pulse ratios. Because consensus was not reached between the USGS/LLNL and LANL on several fundamental points, including the conceptual strategy for sampling, interpretation and use of tritium ({sup 3}H) data, and the importance and interpretation of blanks, in addition to the presence or absence of bomb-pulse {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>, an evaluation by an independent entity, the University of Nevada, Las Vegas (UNLV), using new samples was initiated. This report is the result of that study. The overall objectives of the UNLV study were to investigate the source or sources of the conflicting results from the previous validation study</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012MSAIS..20...90F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012MSAIS..20...90F"><span id="translatedtitle">Vesta thermal models</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Formisano, M.; Federico, C.; Coradini, A.</p> <p></p> <p>Vesta thermal evolution and structural models are compared. These models, based on decay of <span class="hlt">26</span><span class="hlt">Al</span>, 60Fe and long-lived radionuclides (40K, 232Th, 235U and 238U), differ for the delay in injection (Delta td) of <span class="hlt">26</span><span class="hlt">Al</span> by the nebula in which Vesta was formed. In all models we can see the pristine formation of a metallic core followed by the differentiation of silicatic mantle and we can observe the evolution of the crust. This is in preparation of the Dawn mission that will provide us with constraints on the crust thickness and composition of the crust and underlying mantle.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016LPICo1921.6080U','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016LPICo1921.6080U"><span id="translatedtitle">Evidence for a Long Duration of the 16O-Rich Reservoir in the Solar Nebula</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ushikubo, T.; Tenner, T. J.; Hiyagon, H.; Kita, N. T.</p> <p>2016-08-01</p> <p>Oxygen isotope ratios and <span class="hlt">26</span><span class="hlt">Al</span>-26Mg systematics of a pyroxene-anorthite-rich CAI from Acfer 094 suggest decomposition of melilite occurred in an 16O-rich environment at ~2.3 million years after normal CAI formation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/10103810','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/10103810"><span id="translatedtitle">Shape changes and isospin purity in highly excited light mass nuclei</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kicinska-Habior, M. |; Snover, K.A.; Behr, J.A.; Gossett, C.A.; Gundlach, J.H.; Drebi, Z.M.; Kaplan, M.S.; Wells, D.P.</p> <p>1993-11-01</p> <p>The statistical decay of the Giant Dipole Resonance built on a highly excited states of light-mass nuclei was studied in inclusive experiments. Results of the search for a shape change of hot, fast-rotating {sup 45}Sc and the test of the isospin purity at high excitation in {sup 28}Si and {sup <span class="hlt">26</span>}<span class="hlt">Al</span> are reported.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2011-title21-vol3/pdf/CFR-2011-title21-vol3-sec182-60.pdf','CFR2011'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2011-title21-vol3/pdf/CFR-2011-title21-vol3-sec182-60.pdf"><span id="translatedtitle">21 CFR 182.60 - Synthetic flavoring substances and adjuvants.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2011 CFR</a></p> <p></p> <p>2011-04-01</p> <p>... (parapropenyl anisole). Benzaldehyde (benzoic aldehyde). N-Butyric acid (butanoic acid). d- or l-Carvone (carvol). Cinnamaldehyde (cinnamic aldehyde). Citral (2,6-dimethyloctadien-2,6-al-8, gera-nial, neral). Decanal (N...-Methyl-3-phenyl glycidic acid ethyl ester (ethyl-methyl-phenyl-glycidate, so-called strawberry...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title21-vol3/pdf/CFR-2010-title21-vol3-sec182-60.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title21-vol3/pdf/CFR-2010-title21-vol3-sec182-60.pdf"><span id="translatedtitle">21 CFR 182.60 - Synthetic flavoring substances and adjuvants.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-04-01</p> <p>... (parapropenyl anisole). Benzaldehyde (benzoic aldehyde). N-Butyric acid (butanoic acid). d- or l-Carvone (carvol). Cinnamaldehyde (cinnamic aldehyde). Citral (2,6-dimethyloctadien-2,6-al-8, gera-nial, neral). Decanal (N...-Methyl-3-phenyl glycidic acid ethyl ester (ethyl-methyl-phenyl-glycidate, so-called strawberry...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2012-title21-vol3/pdf/CFR-2012-title21-vol3-sec182-60.pdf','CFR2012'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2012-title21-vol3/pdf/CFR-2012-title21-vol3-sec182-60.pdf"><span id="translatedtitle">21 CFR 182.60 - Synthetic flavoring substances and adjuvants.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2012&page.go=Go">Code of Federal Regulations, 2012 CFR</a></p> <p></p> <p>2012-04-01</p> <p>... (parapropenyl anisole). Benzaldehyde (benzoic aldehyde). N-Butyric acid (butanoic acid). d- or l-Carvone (carvol). Cinnamaldehyde (cinnamic aldehyde). Citral (2,6-dimethyloctadien-2,6-al-8, gera-nial, neral). Decanal (N...-Methyl-3-phenyl glycidic acid ethyl ester (ethyl-methyl-phenyl-glycidate, so-called strawberry...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2013-title21-vol3/pdf/CFR-2013-title21-vol3-sec182-60.pdf','CFR2013'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2013-title21-vol3/pdf/CFR-2013-title21-vol3-sec182-60.pdf"><span id="translatedtitle">21 CFR 182.60 - Synthetic flavoring substances and adjuvants.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a></p> <p></p> <p>2013-04-01</p> <p>... (parapropenyl anisole). Benzaldehyde (benzoic aldehyde). N-Butyric acid (butanoic acid). d- or l-Carvone (carvol). Cinnamaldehyde (cinnamic aldehyde). Citral (2,6-dimethyloctadien-2,6-al-8, gera-nial, neral). Decanal (N...-Methyl-3-phenyl glycidic acid ethyl ester (ethyl-methyl-phenyl-glycidate, so-called strawberry...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JPhCS.730a2003A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JPhCS.730a2003A"><span id="translatedtitle">The 28Si(d,α) reaction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Araujo-Escalona, V.; Acosta, L.; Andrade, E.; Barrón-Palos, L.; Cantó, C.; Favela, F.; Huerta, A.; Ortiz, M. E.; Solís, C.; Chávez, E.</p> <p>2016-07-01</p> <p>Recent techniques and experimental methods open up new ways to explore nuclear reactions relevant to nucleosynthesis at stellar combustion temperatures. In this work we focus on the case of <span class="hlt">26</span><span class="hlt">Al</span>, isotope associated with the identification of active nucleosynthesis spots in the cosmos. Its presence in the solar system was unexpected until it was found in the Allende meteorite. It is now understood that cosmic rays induce nuclear reactions to produce <span class="hlt">26</span><span class="hlt">Al</span>. On Earth, this process is well known and is the basis of many environmental studies. So <span class="hlt">26</span><span class="hlt">Al</span> is not just the product of some high-metallicity star collapse. Natural Silicon targets were irradiated with deuteron beams of energies between 0.9 and 2.6 MeV. The produced <span class="hlt">26</span><span class="hlt">Al</span> were counted later-on in an AMS facility. In this paper, we describe in detail the experimental protocol developed to quantify the number of deuterons hitting the target, as a first step to determine the total cross section.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016LPICo1921.6238M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016LPICo1921.6238M"><span id="translatedtitle">Al-Mg Systematics of Wark-Lovering Rims Around a Refractory Inclusion from the NWA 5028 CR2 Chondrite</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mane, P.; Bose, M.; Wadhwa, M.</p> <p>2016-08-01</p> <p>We report Al-Mg relative ages of Wark-Lovering rims and the host CAI. A hibonite + spinel layer of the rim sequence shows canonical initial <span class="hlt">26</span><span class="hlt">Al</span>/27Al ratio, suggesting a contemporaneous formation of these rims and its host CAI.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014EPJA...50..147C&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014EPJA...50..147C&link_type=ABSTRACT"><span id="translatedtitle">A new study of 25Mg 28Si angular distributions at MeV</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Caciolli, A.; Marchi, T.; Depalo, R.; Appannababu, S.; Blasi, N.; Broggini, C.; Cinausero, M.; Collazuol, G.; Degerlier, M.; Fabris, D.; Gramegna, F.; Leone, M.; Mastinu, P.; Menegazzo, R.; Montagnoli, G.; Rossi Alvarez, C.; Rigato, V.; Wieland, O.</p> <p>2014-09-01</p> <p>The observation of <span class="hlt">26</span><span class="hlt">Al</span> gives us the proof of active nucleosynthesis in the Milky Way. However the identification of the main producers of <span class="hlt">26</span><span class="hlt">Al</span> is still a matter of debate. Many sites have been proposed, but our poor knowledge of the nuclear processes involved introduces high uncertainties. In particular, the limited accuracy on the 25Mg 28Si reaction cross section has been identified as the main source of nuclear uncertainty in the production of <span class="hlt">26</span><span class="hlt">Al</span> in C/Ne explosive burning in massive stars, which has been suggested to be the main source of <span class="hlt">26</span><span class="hlt">Al</span> in the Galaxy. We studied this reaction through neutron spectroscopy at the CN Van de Graaff accelerator of the Legnaro National Laboratories. Thanks to this technique we are able to discriminate the events from possible contamination arising from parasitic reactions. In particular, we measured the neutron angular distributions at 5 different beam energies (between 3 and 5 MeV) in the - laboratory system angular range. The presented results disagree with the assumptions introduced in the analysis of a previous experiment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011APS..DNP.EA050F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011APS..DNP.EA050F"><span id="translatedtitle">Analysis of the Farmville Meteorite</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ferm, Megan</p> <p>2011-10-01</p> <p>Meteoroids are objects that are constantly bombarded by cosmic rays in outer space. Through spallation reactions between cosmic rays and meteoroid matter, radioactive nuclides, such as <span class="hlt">26</span><span class="hlt">Al</span>, are produced. <span class="hlt">26</span><span class="hlt">Al</span> is a positron emitter, meaning that the positron annihilates within a cubic millimeter of the sample. This results in the release of two 511 keV photons, in addition to an 1809 keV gamma ray from the decay to the 26Mg ground state. This study focuses on the detection of <span class="hlt">26</span><span class="hlt">Al</span> in the Farmville meteorite, which fell in North Carolina in 1934. The meteorite has been centered in our sensitive apparatus, and the conditions for detection require a triple gamma coincidence which greatly reduced background. With the radioisotopes measured within the sample, Monte Carlo transport simulations (using the package Geant4) will be performed to determine the amount of <span class="hlt">26</span><span class="hlt">Al</span> in the meteorite. With this information, it may be possible to determine the time the meteorite entered Earth's atmosphere (which should be consistent with the reported find time), the time period that the meteoroid was exposed to the cosmic rays, the pre-atmospheric size of the meteoroid and the intensity of cosmic rays in the inner solar system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016LPICo1921.6204N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016LPICo1921.6204N"><span id="translatedtitle">Explosive H-Burning and Neutron Capture Isotopic Signatures in 13C- and 15N-Rich Presolar SiC Grains</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nittler, L. R.; Liu, N.; Alexander, C. M. O'D.; Wang, J.</p> <p>2016-08-01</p> <p>15N-rich SiC AB grains have correlated <span class="hlt">26</span><span class="hlt">Al</span>/27Al and N-isotopic ratios and evidence for neutron capture (50Ti and 32S excesses), indicating combined effects of explosive H burning and neutron capture. The origin(s) of these grains remains elusive.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.H13E1395P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.H13E1395P"><span id="translatedtitle">Perchlorate in The Great Lakes: Distribution, Isotopic Composition and Origin</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Poghosyan, A.; Sturchio, N. C.; Jackson, W. A.; Guan, Y.; Eiler, J. M.; Hatzinger, P. B.</p> <p>2013-12-01</p> <p>Concentrations, stable chlorine and oxygen isotopic compositions, and <span class="hlt">36</span><span class="hlt">Cl</span> abundances of perchlorate were investigated in the five Laurentian Great Lakes. Samples were collected during monitoring cruises in 2007 and 2008 of the U.S. EPA's RV Lake Guardian and in 2010 at the water supply intake of Marquette, MI on the southern shore of Lake Superior. Concentrations of perchlorate were measured by IC/MS/MS at 24 locations, including one or two depth profiles in each lake. Mean concentrations (μg/L) are: Superior, 0.06 × 0.01; Michigan, 0.10 × 0.01; Huron, 0.11 × 0.01; Erie, 0.08 × 0.01, and Ontario, 0.09 × 0.01. Concentration vs. depth is nearly constant in each lake, indicating well-mixed conditions. Perchlorate was extracted from near-surface water by passing 15,000 to 80,000 L of water through 1-L cartridges containing Purolite A530E bifunctional anion-exchange resin. In the laboratory, perchlorate was eluted from the resin, purified, and precipitated as a >99% pure crystalline phase. Milligram amounts were recovered from each lake. Chlorine and oxygen isotopic analyses were performed at Caltech using the Cameca 7f-GEO SIMS instrument, following validation of the SIMS method with analyses of USGS-37 and USGS-38 isotopic reference materials. Results indicate a relatively narrow range in δ37Cl values (+2.9 to +3.9 ‰) and a wider range in δ18O values (-4.0 to +4.1 ‰), with a general geographic trend of increasing δ18O from west to east. Oxygen-17 was measured at UIC using dual-inlet IRMS of O2 produced by decomposition of KClO4. Great Lakes perchlorate has mass-independent oxygen isotopic variations with positive Δ17O values (+1.6 ‰ to +2.7 ‰) divided into two distinct groups: Lake Superior (+2.7 ‰) and the other four lakes (~ +1.7 ‰). The isotopic data indicate that perchlorate is dominantly of natural origin, having stable isotopic compositions resembling those of perchlorate from pre-industrial groundwaters in the western USA. The <span class="hlt">36</span><span class="hlt">Cl</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24429108','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24429108"><span id="translatedtitle">Functional coupling of chloride-proton exchanger ClC-5 to gastric H+,K+-ATPase.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Takahashi, Yuji; Fujii, Takuto; Fujita, Kyosuke; Shimizu, Takahiro; Higuchi, Taiga; Tabuchi, Yoshiaki; Sakamoto, Hisato; Naito, Ichiro; Manabe, Koji; Uchida, Shinichi; Sasaki, Sei; Ikari, Akira; Tsukada, Kazuhiro; Sakai, Hideki</p> <p>2014-01-01</p> <p>It has been reported that chloride-proton exchanger ClC-5 and vacuolar-type H(+)-ATPase are essential for endosomal acidification in the renal proximal cells. Here, we found that ClC-5 is expressed in the gastric parietal cells which secrete actively hydrochloric acid at the luminal region of the gland, and that it is partially localized in the intracellular tubulovesicles in which gastric H(+),K(+)-ATPase is abundantly expressed. ClC-5 was co-immunoprecipitated with H(+),K(+)-ATPase in the lysate of tubulovesicles. The ATP-dependent uptake of (<span class="hlt">36</span>)<span class="hlt">Cl</span>(-) into the vesicles was abolished by 2-methyl-8-(phenylmethoxy)imidazo[1,2-a]pyridine-3-acetonitrile (SCH28080), an inhibitor of H(+),K(+)-ATPase, suggesting functional expression of ClC-5. In the tetracycline-regulated expression system of ClC-5 in the HEK293 cells stably expressing gastric H(+),K(+)-ATPase, ClC-5 was co-immunoprecipitated with H(+),K(+)-ATPase, but not with endogenous Na(+),K(+)-ATPase. The SCH28080-sensitive (<span class="hlt">36</span>)<span class="hlt">Cl</span>(-) transporting activity was observed in the ClC-5-expressing cells, but not in the ClC-5-non-expressing cells. The mutant (E211A-ClC-5), which has no H(+) transport activity, did not show the SCH28080-sensitive (<span class="hlt">36</span>)<span class="hlt">Cl</span>(-) transport. On the other hand, both ClC-5 and its mutant (E211A) significantly increased the activity of H(+),K(+)-ATPase. Our results suggest that ClC-5 and H(+),K(+)-ATPase are functionally associated and that they may contribute to gastric acid secretion.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5459599','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5459599"><span id="translatedtitle">Differences in GABA-induced chloride ion influx in brain of inbred mouse strains</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Yu, O.; Chiu, T.H.; Rosenberg, H.C.</p> <p>1986-03-01</p> <p>Audiogenic seizure-susceptible (AS) mice (DBA2J) are a widely used model of epilepsy. The precise pathophysiology of this mouse strain is not fully understood. One of the proposed mechanisms was a difference in GABA/BZ receptor affinity and population from that of audiogenic seizure resistant (ASR) mice. This study attempted to determine the difference in function of GABA/BZ receptor between DBA2J (AS) and C57BL6J (ASR) mice by directly measuring the GABA-induced chloride ion (/sup <span class="hlt">36</span>/<span class="hlt">Cl</span>/sup -/) influx in twice washed crude brain homogenates. /sup <span class="hlt">36</span>/<span class="hlt">Cl</span>/sup -/ influx was terminated by ice-cold buffer and collected by filtration. A concentration range of 2-1000 ..mu..M GABA and two age-matched groups (20-22 days and 40-42 days) were used. GABA-induced /sup <span class="hlt">36</span>/<span class="hlt">Cl</span>/sup -/ influx was dose-dependent, and brain homogenates from DBA2J mice (20-22 days) were less sensitive to GABA-induced Cl/sup -/ ion influx than C57BL6J mice at both age groups. However, in older DBA2J mice (40-42 days), the sensitivity to GABA was intermediate between that of the younger AS mice and the control ASR mice. No significant difference in basal influx of Cl/sup -/ was observed between age groups and mouse strains, nor was there any significant difference between 20-22 days old and 40-42 days old C57BL6J mice. In conclusion, this study had demonstrated a malfunction may recover with age.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_21 --> <div id="page_22" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="421"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015NIMPB.361..649W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015NIMPB.361..649W"><span id="translatedtitle">Using the nuclear activation AMS method for determining chlorine in solids at ppb-levels and below</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Winkler, Stephan R.; Eigl, Rosmarie; Forstner, Oliver; Martschini, Martin; Steier, Peter; Sterba, Johannes H.; Golser, Robin</p> <p>2015-10-01</p> <p>Neutron activation analysis using decay counting of the activated element is a well-established method in elemental analysis. However, for chlorine there is a better alternative to measuring decay of the short-lived activation product chlorine-38 (t1/2 = 37.24 min) - accelerator mass spectrometry (AMS) of <span class="hlt">36</span><span class="hlt">Cl</span>: the relatively high neutron capture cross section of chlorine-35 for thermal neutrons (43.7 b) and combined the AMS technique for chlorine-36 (t1/2 = 301 ka) allow for determination of chlorine down to ppb-levels using practical sample sizes and common exposure durations. The combination of neutron activation and AMS can be employed for a few other elements (nitrogen, thorium, and uranium) as well. For bulk solid samples an advantage of the method is that lab contamination can be rendered irrelevant. The chlorine-35 in the sample is activated to chlorine-36, and surface chlorine can be removed after the irradiation. Subsequent laboratory contamination, however, will not carry a prominent chlorine-36 signature. After sample dissolution and addition of sufficient amounts of stable chlorine carrier the produced chlorine-36 and thus the original chlorine-35 of the sample can be determined using AMS. We have developed and applied the method for analysis of chlorine in steel samples. The chlorine content of steel is of interest to nuclear industry, precisely because of above mentioned high neutron capture cross section for chlorine-35, which leads to accumulation of chlorine-36 as long-term nuclear waste. The samples were irradiated at the TRIGA Mark II reactor of the Atominstitut in Vienna and the <span class="hlt">36</span><span class="hlt">Cl</span>-AMS setup at the Vienna Environmental Research Accelerator (VERA) was used for <span class="hlt">36</span><span class="hlt">Cl</span>/Cl analysis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/21030390','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/21030390"><span id="translatedtitle">Contrast in chloride exclusion between two grapevine genotypes and its variation in their hybrid progeny.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Gong, Haijun; Blackmore, Deidre; Clingeleffer, Peter; Sykes, Steve; Jha, Deepa; Tester, Mark; Walker, Rob</p> <p>2011-01-01</p> <p>Potted grapevines of 140 Ruggeri (Vitis berlandieri × Vitis rupestris), a good Cl(-) excluder, and K 51-40 (Vitis champinii × Vitis riparia 'Gloire'), a poor Cl(-) excluder, and of a family obtained by crossing the two genotypes, were used to examine the inheritance of Cl(-) exclusion. Rooted leaves were then used to further investigate the mechanism for Cl(-) exclusion in 140 Ruggeri. In both a potting mix trial (plants watered with 50 mM Cl(-)) and a solution culture trial (plants grown in 25 mM Cl(-)), the variation in Cl(-) accumulation was continuous, indicating multiple rather than single gene control for Cl(-) exclusion between hybrids within the family. Upper limits of 42% and 35% of the phenotypic variation in Cl(-) concentration could be attributed to heritable sources in the potting mix and solution culture trials, respectively. Chloride transport in roots of rooted leaves of both genotypes appeared to be via the symplastic pathway, since addition of 8-hydroxy-1,3,6-pyrenetrisulphonic acid (PTS), an apoplastic tracer, revealed no obvious PTS fluorescence in the laminae of either genotype, despite significant accumulation of Cl(-) in laminae of K 51-40 during the PTS uptake period. There was no significant difference in either unidirectional (<span class="hlt">36</span>)<span class="hlt">Cl</span>(-) flux (10 min) or (<span class="hlt">36</span>)<span class="hlt">Cl</span>(-) uptake (3 h) into roots of rooted leaves exposed to 5, 10, or 25 mM Cl(-). However, the percentage of (<span class="hlt">36</span>)<span class="hlt">Cl</span>(-) transported to the lamina (3 h) was significantly lower in 140 Ruggeri than in K 51-40, supporting reduced Cl(-) loading into xylem and implicating the root stele in the Cl(-) exclusion mechanism. PMID:21030390</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016Geomo.273..412C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016Geomo.273..412C"><span id="translatedtitle">Timing and nature of alluvial fan development along the Chajnantor Plateau, northern Chile</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cesta, Jason M.; Ward, Dylan J.</p> <p>2016-11-01</p> <p>Alluvial systems in the Atacama Desert provide a unique opportunity to elucidate the sedimentary response to climate variability, particularly changes in precipitation, in hyperarid environments. Alluvial fans along the eastern margin of the Salar de Atacama, adjacent to the Chajnantor Plateau in the Atacama Desert of northern Chile, provide an archive of climate-modulated sediment transfer and erosion at an extreme of Earth's climate. Three regional alluvial fan surfaces (Qf1 [oldest] to Qf3 [youngest]) were mapped along the western flank of the Chajnantor Plateau. The alluvial fans were examined with geomorphic and terrestrial cosmogenic <span class="hlt">36</span><span class="hlt">Cl</span> surface exposure dating methods to define the timing of alluvial fan formation and to determine the role of climatic processes on fan development in a hyperarid environment. Alluvial fans in the study area are comprised of hyperconcentrated flow and boulder-rich debris flow deposits that reflect deposition transitioning between cohesive and noncohesive regimes. Alluvial fan surfaces yield exposure ages that range from 49.6 ± 4.4 to 194 ± 12 ka, while debris flow boulders yield exposure ages ranging from 12.4 ± 2.1 to 229 ± 53 ka. Cosmogenic <span class="hlt">36</span><span class="hlt">Cl</span> exposure ages indicate that abandonment of alluvial fan surfaces Qf1, Qf2, and Qf3 date to 175 ± 22.6 ka (MIS 6), 134.5 ± 9.18 ka (MIS 6), and 20.07 ± 6.26 ka (MIS 2), respectively. A <span class="hlt">36</span><span class="hlt">Cl</span> concentration-depth profile through alluvial fan Qf1 suggests a simple depositional history with minimal nuclide inheritance implying relatively rapid aggradation (6 m in ca. 25 kyr) followed by surface abandonment ca. 180-200 ka. Our data support a strong climatic control on alluvial fan evolution in the region, and we propose that the alluvial fans along the margins of the Salar de Atacama form according to the humid model of fan formation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/7013312','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/7013312"><span id="translatedtitle">Ethanol-related changes in benzodiazepine receptor ligand modulation of GABA[sub A] receptor-operated chloride channels: Relevance to ethanol tolerance and dependence</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Buck, K.J.</p> <p>1990-01-01</p> <p>This study focuses on how ethanol exposure affects biochemical processes associated with the GABA[sub A] complex in the mammalian CNS, and examines the role of these changes in the development of alcohol tolerance and withdrawal. In vitro studies of control mice and those acutely or chronically exposed to alcohol were conducted. Radioligand binding using the low-affinity GABA[sub A] receptor-selective antagonist [[sup 3]H]SR95531 showed no changes in saturation binding analysis of receptor affinity or density. Muscimol-activated [sup <span class="hlt">36</span>]<span class="hlt">Cl</span>[sup [minus</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1813608S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1813608S"><span id="translatedtitle">Reconstruction of the Earthquake History of Limestone Fault Scarps in Knidos Fault Zone Using in-situ Chlorine-36 Exposure Dating and "R" Programming Language</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sahin, Sefa; Yildirim, Cengiz; Akif Sarikaya, Mehmet; Tuysuz, Okan; Genc, S. Can; Ersen Aksoy, Murat; Ertekin Doksanalti, Mustafa</p> <p>2016-04-01</p> <p>Cosmogenic surface exposure dating is based on the production of rare nuclides in exposed rocks, which interact with cosmic rays. Through modelling of measured <span class="hlt">36</span><span class="hlt">Cl</span> concentrations, we might obtain information of the history of the earthquake activity. Yet, there are several factors which may impact production of rare nuclides such as geometry of the fault, topography, geographic location of the study area, temporal variations of the Earth's magnetic field, self-cover and denudation rate on the scarp. Recently developed models provides a method to infer timing of earthquakes and slip rates on limited scales by taking into account these parameters. Our study area, the Knidos Fault Zone, is located on the Datça Peninsula in Southwestern Anatolia and contains several normal fault scarps formed within the limestone, which are appropriate to generate cosmogenic chlorine-36 (<span class="hlt">36</span><span class="hlt">Cl</span>) dating models. Since it has a well-preserved scarp, we have focused on the Mezarlık Segment of the fault zone, which has an average length of 300 m and height 12-15 m. 128 continuous samples from top to bottom of the fault scarp were collected to carry out analysis of cosmic <span class="hlt">36</span><span class="hlt">Cl</span> isotopes concentrations. The main purpose of this study is to analyze factors affecting the production rates and amount of cosmogenic <span class="hlt">36</span><span class="hlt">Cl</span> nuclides concentration. Concentration of Cl36 isotopes are measured by AMS laboratories. Through the local production rates and concentration of the cosmic isotopes, we can calculate exposure ages of the samples. Recent research elucidated each step of the application of this method by the Matlab programming language (e.g. Schlagenhauf et al., 2010). It is vitally helpful to generate models of Quaternary activity of the normal faults. We, however, wanted to build a user-friendly program through an open source programing language "R" (GNU Project) that might be able to help those without knowledge of complex math programming, making calculations as easy and understandable as</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6152528','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6152528"><span id="translatedtitle">Antidepressants and seizure-interactions at the GABA-receptor chloride-ionophore complex</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Malatynska, E.; Knapp, R.J.; Ikeda, M.; Yamamura, H.I.</p> <p>1988-01-01</p> <p>Convulsive seizures are a potential side effect of antidepressant drug treatment and can be produced by all classes of antidepressants. It is also know that some convulsant and anticonvulsant drug actions are mediated by the GABA-receptor chloride-ionophore complex. Drugs acting at this complex appear to induce convulsions by inhibiting chloride conductance through the associated chloride channel. Using the method of GABA-stimulated /sup <span class="hlt">36</span>/<span class="hlt">Cl</span>-uptake by rat cerebral cortical vesicles, we show that some antidepressant drugs can inhibit the GABA-receptor chloride uptake, and that the degree of chloride channel inhibition by these drugs correlates with the frequency of convulsive seizures induced by them.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4878341','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4878341"><span id="translatedtitle">Precision Measurement of Fundamental Constants Using GAMS4</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Dewey, M. S.; Kessler, E. G.</p> <p>2000-01-01</p> <p>We discuss the connection of high-energy gamma-ray measurements with precision atomic mass determinations. These rather different technologies, properly combined, are shown to lead to new values for the neutron mass and the molar Planck constant. We then proceed to describe the gamma-ray measurement process using the GAMS4 facility at the Institut Laue-Langevin and its application to a recent measurement of the 2.2 MeV deuteron binding energy and the neutron mass. Our paper concludes by describing the first crystal diffraction measurement of the 8.6 MeV <span class="hlt">36</span><span class="hlt">Cl</span> binding energy. PMID:27551583</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/10647918','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/10647918"><span id="translatedtitle">Effects of the chlorotriazine herbicide, cyanazine, on GABA(A) receptors in cortical tissue from rat brain.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Shafer, T J; Ward, T R; Meacham, C A; Cooper, R L</p> <p>1999-12-20</p> <p>Chlorotriazine herbicides disrupt luteinizing hormone (LH) release in female rats following in vivo exposure. Although the mechanism of action is unknown, significant evidence suggests that inhibition of LH release by chlorotriazines may be mediated by effects in the central nervous system. GABA(A) receptors are important for neuronal regulation of gonadotropin releasing hormone and LH release. The ability of chlorotriazine herbicides to interact with GABA(A) receptors was examined by measuring their effects on [3H]muscimol, [3H]Ro15-4513 and [35S]tert-butylbicyclophosphorothionate (TBPS) binding to rat cortical membranes. Cyanazine (1-400 microM) inhibited [3H]Ro15-4513 binding with an IC50 of approximately 105 microM (n=4). Atrazine (1-400 microM) also inhibited [3H]Ro15-4513 binding, but was less potent than cyanazine (IC50 = 305 microM). However, the chlorotriazine metabolites diaminochlorotriazine, 2-amino-4-chloro-6-ethylamino-s-triazine and 2-amino-4-chloro-6-isopropylamino-s-triazine were without significant effect on [3H]Ro15-4513 binding. Cyanazine and the other chlorotriazines were without effect on [3H]muscimol or [35S]TBPS binding. To examine whether cyanazine altered GABA(A) receptor function, GABA-stimulated <span class="hlt">36</span><span class="hlt">Cl</span>- flux into synaptoneurosomes was examined. Cyanazine (50-100 microM) alone did not significantly decrease GABA-stimulated <span class="hlt">36</span><span class="hlt">Cl</span>- flux. Diazepam (10 microM) and pentobarbital (100 microM) potentiated GABA-stimulated <span class="hlt">36</span><span class="hlt">Cl</span>- flux to 126 and 166% of control, respectively. At concentrations of 50 and 100 microM, cyanazine decreased potentiation by diazepam to 112 and 97% of control, respectively, and decreased potentiation by pentobarbital to 158 and 137% of control (n = 6). Interestingly, at lower concentrations (5 microM), cyanazine shifted the EC50 for GABA-stimulated <span class="hlt">36</span><span class="hlt">Cl</span>- flux into synaptoneurosomes from 28.9 to 19.4 microM, respectively (n = 5). These results suggest that cyanazine modulates benzodiazepine, but not the muscimol (GABA receptor</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22069003','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22069003"><span id="translatedtitle">Experimental study of upper sd shell nuclei and evolution of sd-fp shell gap</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Sarkar, M. Saha</p> <p>2012-06-27</p> <p>The intruder orbitals from the fp shell play important role in the structure of nuclei around the line of stability in the upper sd shell. Experimentally we have studied {sup 35}Cl, {sup 30}P, {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>, {sup 37}Ar and {sup 34}Cl in this mass region using the INGA setup. Large basis cross-shell shell model calculations have indicated the need for change of the sd-fp energy gap for reliable reproduction of negative parity and high spin positive parity states. Indication of population of states of large deformation has been found in our data. Theoretical interpretation of these states has been discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014E%26PSL.390..318M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014E%26PSL.390..318M"><span id="translatedtitle">Timing and extent of Mg and Al isotopic homogenization in the early inner Solar System</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mishra, Ritesh Kumar; Chaussidon, Marc</p> <p>2014-03-01</p> <p>The first million years of the Solar System is a key period when the first solids were formed from the nebula gas. The chronology of the different processes at the origin of these solids is still largely unknown and relies strongly on the assumption made of homogeneous distribution for short-lived radioactive nuclides such as <span class="hlt">26</span><span class="hlt">Al</span>. This assumption is questioned. In this study, in situ <span class="hlt">26</span><span class="hlt">Al</span>-26Mg isotope systematics was studied with high precision in 12 calcium, aluminum-rich inclusions (CAIs) (1 type A, 2 type B, 5 type C, and 4 fine grained spinel-rich), 2 amoeboid olivine aggregates (AOAs), and 2 Al-rich chondrules from Efremovka and Vigarano. The (<span class="hlt">26</span><span class="hlt">Al</span>/27Al)i in these early Solar System solids (the subscript ‘i’ stands for the initial isotope ratio obtained from the mineral <span class="hlt">26</span><span class="hlt">Al</span> isochron) range from ∼6.5×10-5 to 0.2×10-5 with δMgi*26 from -0.08 to +0.37‰. The (<span class="hlt">26</span><span class="hlt">Al</span>/27Al)i and δMgi*26 of CAIs and chondrules can be explained by formation of their precursors from a homogeneous reservoir (Solar System Initial, noted hereafter SSI) with initial magnesium isotopic composition of δMgSSI*26=-0.052±0.013‰ and initial (<span class="hlt">26</span><span class="hlt">Al</span>/27Al)SSI abundance of (5.62±0.42)×10-5. The high precision magnesium isotope data obtained in the present study and literature data allows identifying a few epochs of formation/reprocessing of CAIs. The time periods of these epochs correspond well with the median life times of the pre-main sequence evolution of stars of Solar mass if we anchor the (Al<span class="hlt">26</span>/<span class="hlt">Al</span>27)SSI=(5.62±0.42)×10-5 to the beginning of class I phase. This provides a natural explanation to the range of (<span class="hlt">26</span><span class="hlt">Al</span>/27Al)i - (∼6 to 0.02) × 10-5 seen in corundum grains, FUN (Fractionation and Unidentified Nuclear Effects) CAIs, ultrarefractory CAIs, normal CAIs, and chondrules, and suggests a possible relationship between the astrophysical conditions and the formation of these early solids. Corundum grains, FUN CAIs, ultrarefractory CAIs would have formed during the class 0 of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1022885','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1022885"><span id="translatedtitle">Renewed Search for FUN (Fractionated and Unidentified Nuclear Effects) in Primitive Chondrites</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Tollstrup, D L; Wimpenny, J B; Yin, Q -; Ebel, D S; Jacobsen, B; Hutcheon, I D</p> <p>2011-04-07</p> <p>Ca-Al-rich inclusions (CAIs) found in primitive chondrites record processes and conditions of the earliest solar system as they are the oldest known solid objects formed in the solar system [1,2]. CAIs with fractionation and unidentified nuclear anomalies (FUN CAIs; [3]) are very rare and thusfar found exclusively in CV carbonaceous chondrites (e.g., Allende and Vigarano)[4]. FUN CAIs are characterized by large nucleosynthetic anomalies in several elements (Ca, Ti, Si, Sr, Ba, Nd, and Sm), large mass-dependant isotope fractionation (Mg, Si, and O), and very little initial {sup <span class="hlt">26</span>}<span class="hlt">Al</span> [4,5 and reference therein]. Formation of FUN CAIs by thermal processing of presolar dust aggregates prior to the injection of {sup <span class="hlt">26</span>}<span class="hlt">Al</span> into the protoplanetary disk has been proposed. More recently [5] proposed that FUN CAIs formed from a protosolar molecular cloud after injection of {sup <span class="hlt">26</span>}<span class="hlt">Al</span> but before {sup <span class="hlt">26</span>}<span class="hlt">Al</span> and {sup 27}Al were completely homogenized. Therefore discovering more FUN CAIs to perform U-Pb and other short-lived chronometric dating will provide key constraints on the age of the solar system, the isotopic composition of the protosolar molecular cloud, the earliest stages of the thermal processing in the solar system and the timing of {sup <span class="hlt">26</span>}<span class="hlt">Al</span> and other short-lived radionuclide injection into the nascent solar system. Most known FUN CAIs were discovered and studied > 30 yr ago, and their isotope ratios determined using thermal ionization mass spectrometry (TIMS). Most of these FUN CAIs were almost or entirely consumed during their respective analyses. [5] recently identified a new FUN CAI (NWA 779 KS-1) based on O and Mg isotope ratios determined by SIMS and MCICPMS, respectively. We have initiated a systematic search for FUN CAIs in primitive chondrites, taking advantage of the large mass-dependant Mg isotope effects known for FUN inclusions with little or no inferred {sup <span class="hlt">26</span>}<span class="hlt">Al</span>. Our strategy is to use newly developed sample cells capable of holding very large</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19860042318&hterms=iron+hydroxides&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Diron%2Bhydroxides','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19860042318&hterms=iron+hydroxides&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Diron%2Bhydroxides"><span id="translatedtitle">Determination of cosmogenic Ca-41 in a meteorite with tandem accelerator mass spectrometry</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kubik, P. W.; Elmore, D.; Conard, N. J.; Nishiizumi, K.; Arnold, J. R.</p> <p>1986-01-01</p> <p>The first use of tandem accelerator mass spectrometry (TAMS) to measure the content of Ca-41 in a natural sample, the iron Bogou meteorite, is reported. Ca in the samples was extracted by hydroxide precipitation and purified by means of a caution exchange resin (AG 50W-X8). After adding 4 percent ammonium oxide, the precipitate was ignited to CaO in a quartz vial at about 1100 C. The Ca-<span class="hlt">41</span>/<span class="hlt">Ca</span> ratios were determined following acceleration by alternate measurements of the Ca-40 beam current in an image Faraday cup. Ca-41 particles were also measured using a gas counter. The measured Ca-<span class="hlt">41</span>/<span class="hlt">Ca</span> ratio was 3.8 + or -0.6 x 10 to the 12th, which corresponds to a Ca-41 activity of 6.9 + or -1.1 d.p.m. per kg. Calculation of the half-life of Ca-41 in the Bogou meteorite yielded an age of 103,000 years.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005NIMPA.551..312G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005NIMPA.551..312G"><span id="translatedtitle">Beta shapefactor determinations by the cutoff energy yield method</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Grau Carles, A.</p> <p>2005-10-01</p> <p>The measurement of spectral deformations due to the forbiddenness of β transitions is commonly resolved by fitting a Kurie plot to experimental data. However, the autoabsorption of the sample and the presence of electromagnetic interferences frequently modify the expected spectral shape, making the determination of the shapefactor function inaccurate in semiconductor and magnetic spectrometers. Although the problem of autoabsorption is not present in liquid-scintillation samples, the sum-coincidence process for pulses and the poor resolution of scintillation spectrometers complicate the deconvolution of the spectra. The goal of this paper is to measure shapefactor functions by making use of observables, such as the maximum point or the cutoff energy yield, which are invariant under resolution changes. As a test of the method, the shapefactor coefficients of the six β-emitters, <span class="hlt">36</span><span class="hlt">Cl</span>, 204Tl, 210Bi, 89Sr, 90Y and 32P are determined from the analysis of the liquid-scintillation pulse-height spectra. Although the results for 210Bi, 89Sr and 90Y are in good agreement with theory, the measured shapefactors for <span class="hlt">36</span><span class="hlt">Cl</span> and 204Tl exhibit similar deviations from theory than those referenced in the literature for the Kurie plots.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27566363','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27566363"><span id="translatedtitle">A new plastic scintillation resin for single-step separation, concentration and measurement of technetium-99.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Barrera, J; Tarancón, A; Bagán, H; García, J F</p> <p>2016-09-14</p> <p>Technetium is a synthetic element with no stable isotopes, produced as waste in nuclear power plants and in cyclotrons used for nuclear medicine. The element has high mobility, in the form of TcO4(-); its determination is therefore important for environmental protection. Technetium is found in low concentrations and therefore common methods for its analysis include long treatments in several steps and require large amounts of reagents for its purification and preconcentration. Plastic scintillation resins (PSresin) are novel materials used to separate, preconcentrate and measure radionuclides in a single step. The objective of this study is to prepare and characterise a PSresin for the preconcentration and measurement of (99)Tc. The study first evaluates the reproducibility of the production of PSresins between batches and over time; showing good reproducibility and storage stability. Next, we studied the effect of some common non-radioactive interferences, showing small influences on measurement, and radioactive interferences ((<span class="hlt">36</span>)<span class="hlt">Cl</span> and (238)U/(234)U). (<span class="hlt">36</span>)<span class="hlt">Cl</span> can be removed by a simple treatment with 0.5 M HCl and (238)U/(234)U can be removed from the column by cleaning with a mixture of 0.1 M HNO3 and 0.1 M HF. In the latter case, a slight change in the morphology of the PSresin caused an increase in detection efficiency. Finally, the PSresin was applied to the measurement of real spiked samples (sea water and urine) with deviations lower than 10% in all cases.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6743163','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6743163"><span id="translatedtitle">Transmembrane chloride flux in tissue-cultured chick heart cells</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Piwnica-Worms, D.; Jacob, R.; Horres, C.R.; Lieberman, M.</p> <p>1983-05-01</p> <p>To evaluate the transmembrane movement of chloride in a preparation of cardiac muscle lacking the extracellular diffusion limitations of natural specimens, intracellular chloride concentration ( (Cl) i) and transmembrane /sup <span class="hlt">36</span>/<span class="hlt">Cl</span> efflux have been determined in growth-oriented embryonic chick heart cells in tissue culture. Using the method of isotopic equilibrium, (Cl)i was 25.1 +/- 7.3 mmol x (liter cell water)-1, comparable to the value of 24.9 +/- 5.4 mmol x (liter cell water)-1 determined by coulometric titration. Two cellular /sup <span class="hlt">36</span>/<span class="hlt">Cl</span> compartments were found; one exchanged with a rate constant of 0.67 +/- 0.12 min-1 and was associated with the cardiac muscle cells; the other, attributed to the fibroblasts, exchanged with a rate constant of 0.18 +/- 0.05 min-1. At 37 degrees C, transmembrane Cl flux of cardiac muscle under steady-state conditions was 30 pmol x cm-2 x s-1. In K-free, normal, or high-Ko solutions, the responses of the membrane potential to changes in external Cl concentration suggested that chloride conductance was low. These results indicate that Cl transport across the myocardial cell membrane is more rapid than K transport and is largely electrically silent.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21951029','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21951029"><span id="translatedtitle">Extended utility of molten-salt chemistry: unprecedented synthesis of a water-soluble salt-inclusion solid comprised of high-nuclearity vanadium oxide clusters.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Queen, Wendy L; West, J Palmer; Hudson, Joan; Hwu, Shiou-Jyh</p> <p>2011-11-01</p> <p>Polyoxometallates (POMs) are desirable in materials applications ranging from uses as catalysts in selective oxidation reactions to molecular-like building blocks for the preparation of new extended solids. With the use of an unprecedented approach involving high temperature, molten salt methods, a fascinating series of salt-inclusion solids (SISs) that contain high nuclearity POMs has been isolated for the first time. Cs(11)Na(3)(V(15)O(<span class="hlt">36</span>))<span class="hlt">Cl</span>(6) (1) was synthesized using the eutectic NaCl/CsCl flux (mp 493 °C) which serves as a reactive solvent in crystal growth and allows for the SIS formation. Its framework can be viewed as an "ionic" lattice composed of alternately packed counterions of Cl-centered [V(15)O(<span class="hlt">36</span>)<span class="hlt">Cl</span>](9-) clusters (V15; S = 11/2) and multinuclear [Cs(9)Na(3)Cl(5)](7+) cations. In light of the structural analysis, 1 was proven to be soluble in water giving rise to a dark green solution that is similar in color to single crystals of the title compound. Infrared spectroscopy of the solid formed from fast evaporation of the solution supports the presence of dissolved V15 clusters. Also noteworthy is the magnetization of 1 at 2 K, which reveals an s-shaped plot resembling that of superparamagnetic materials.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5746120','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5746120"><span id="translatedtitle">Feasibility Study: Applicability of geochronologic methods involving radiocarbon and other nuclides to the groundwater hydrology of the Rustler Formation, southeastern New Mexico</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Lambert, S.J.</p> <p>1987-12-01</p> <p>Radiocarbon, tritium, and /sup <span class="hlt">36</span>/<span class="hlt">Cl</span> were measured in groundwaters from the dolomite aquifers of the Rustler Formation in the northern Delaware Basin of southeastern New Mexico to determine the feasibility of using these nuclides in dating the groundwater at and near the Waste Isolation Pilot Plant, a facility for geological disposal of Radioactive waste. No measurable /sup <span class="hlt">36</span>/<span class="hlt">Cl</span> was found in any of these groundwaters, which derive their dissolved chloride from Permian evaporites. Demonstrably uncontaminated groundwaters contained no significant amounts of tritium (<0.2 TU). Percent modern carbon (PMC) correlates linearly and directly with bicarbonate concentration, indicating mixing of a high-PMC/high-bicarbonate reservoir with a low-PMC/low-bicarbonate reservoir. This relationship together with the history of development of the wells sampling the groundwaters, indicates contamination by anthropogenic modern carbon rather than simple dilution by dissolving rock carbonate. /delta//sup 13/C does not linearly correlate with bicarbonate, indicating no single source of contaminant radiocarbon. Values of PMC and /delta//sup 13/C for groundwaters were used to calculate apparent radiocarbon ages according to an interpretive model that accounts for water/rock interactions in carbonate aquifers. All but six pairs of values give significant negative ages (/minus/1,000 to /minus/7,000 years). This suggests that in contaminated samples the model over-adjusts (based on /delta//sup 13/C) for radiocarbon loss due to dilution and isotopic exchange with the rock. 52 refs., 10 figs., 6 tabs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18662844','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18662844"><span id="translatedtitle">Assessing field-scale migration of radionuclides at the Nevada Test Site: "mobile" species.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hu, Q H; Rose, T P; Zavarin, M; Smith, D K; Moran, J E; Zhao, P H</p> <p>2008-10-01</p> <p>Many long-lived radionuclides are present in groundwater at the Nevada Test Site (NTS) as a result of 828 underground nuclear weapons tests conducted between 1951 and 1992. In conjunction with a comprehensive geochemical review of radionuclides (3H, 14C, <span class="hlt">36</span><span class="hlt">Cl</span>, 99Tc and 129I) that are presumably mobile in the subsurface, we synthesized a body of radionuclide activity data measured from groundwater samples collected at 18 monitoring wells, to qualitatively assess their migration at the NTS over distances of hundreds of meters and over timescales of decades. Tritium and <span class="hlt">36</span><span class="hlt">Cl</span> showed little evidence of retardation, while the transport of 14C may have been retarded by its isotopic exchange with carbonate minerals in the aquifer. Observed local reducing conditions (either natural or test-induced) will impact the mobility of certain redox-sensitive radionuclides (especially 99Tc) that were otherwise soluble and readily transported under oxidizing conditions. Conversely, strongly oxidizing conditions may impact the mobility of 129I which is mobile under reducing conditions. The effect of iodine speciation on its transport deserves further attention. Indication of delayed transport of some "mobile" radionuclides (especially 99Tc) in the groundwater at the NTS suggested the importance of redox conditions of the natural system in controlling the fate and transport of radionuclides, which has implications in the enhanced performance of the potential Yucca Mountain repository, located adjacent to the NTS, to store high-level nuclear wastes as well as management of radionuclide contamination in legacy nuclear operations facilities.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/26681','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/26681"><span id="translatedtitle">Significance of apparent discrepanices in water ages derived from atmospheric radionuclides at Yucca Mountain, Nevada</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Liu, B.; Fabryka-Martin, J.; Wolfsberg, A.; Robinson, B.; Sharma, P.</p> <p>1995-02-23</p> <p>Cosmogenic {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> and {sup 14}C produced in the atmosphere are being used to estimate water residence times in the unsaturated zone at Yucca Mountain. Results thus far show a systematic discordance in that {sup 14}C-based ages are generally one to two orders of magnitude younger than {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>-based ages. This lack of concordance probably arises from one or more of the following reasons: (1) different transport mechanisms, e.g., vapor transport for {sup 14}C; (2) different magnitudes and timing of bomb-pulse signals; (3) mixing of waters from different flow paths; and (4) possibly inadequate methods for correcting for the effect of sample contamination by carbon or chlorine from sources other than the infiltrating water. Preliminary numerical simulation results using the FEHMN code suggest that spatial variation in infiltration rates can enhance lateral flow and mixing that leads to discordance in apparent ages depending on the dating technique. Examples are presented to show that disparate radiometric ages are inevitable and to be expected where mixing of waters of markedly different ages occurs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6749537','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6749537"><span id="translatedtitle">Vanadate and fluoride effects on Na sup + -K sup + -Cl sup minus cotransport in squid giant axon</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Altamirano, A.A.; Breitwieser, G.E.; Russel, J.M. )</p> <p>1988-04-01</p> <p>The effects of vanadate and fluoride on the Na{sup +}-K{sup +}-Cl{sup {minus}} cotransporter of the squid giant axon were assessed. In axons not treated with these agents, intracellular dialysis with ATP-depleting fluids caused bumetanide-inhibitable {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> influx to fall with a half time of {approximately}16 min. In the presence of either 40 {mu}M vanadate or 5 mM fluoride, the decay of bumetanide-inhibitable {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> influx was significantly slowed; half time for vanadate-treated axons is 45 min and four fluoride-treated axons is 37 min. These agents are not exerting their effects on Na{sup +}-K{sup +}Cl{sup {minus}} cotransport by influencing the rate of ATP depletion of the axon, since they had no effect on the ATP hydrolysis rate of an optic ganglia homogenate. We therefore suggest that these data support the hypothesis that Na{sup +}-K{sup +}-Cl{sup {minus}} cotransport in squid axons is regulated by a phosphorylation-dephosphorylation mechanism and that vanadate and fluoride reduce the rate of dephosphorylation by inhibiting a protein phosphatase.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_22 --> <div id="page_23" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="441"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27566363','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27566363"><span id="translatedtitle">A new plastic scintillation resin for single-step separation, concentration and measurement of technetium-99.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Barrera, J; Tarancón, A; Bagán, H; García, J F</p> <p>2016-09-14</p> <p>Technetium is a synthetic element with no stable isotopes, produced as waste in nuclear power plants and in cyclotrons used for nuclear medicine. The element has high mobility, in the form of TcO4(-); its determination is therefore important for environmental protection. Technetium is found in low concentrations and therefore common methods for its analysis include long treatments in several steps and require large amounts of reagents for its purification and preconcentration. Plastic scintillation resins (PSresin) are novel materials used to separate, preconcentrate and measure radionuclides in a single step. The objective of this study is to prepare and characterise a PSresin for the preconcentration and measurement of (99)Tc. The study first evaluates the reproducibility of the production of PSresins between batches and over time; showing good reproducibility and storage stability. Next, we studied the effect of some common non-radioactive interferences, showing small influences on measurement, and radioactive interferences ((<span class="hlt">36</span>)<span class="hlt">Cl</span> and (238)U/(234)U). (<span class="hlt">36</span>)<span class="hlt">Cl</span> can be removed by a simple treatment with 0.5 M HCl and (238)U/(234)U can be removed from the column by cleaning with a mixture of 0.1 M HNO3 and 0.1 M HF. In the latter case, a slight change in the morphology of the PSresin caused an increase in detection efficiency. Finally, the PSresin was applied to the measurement of real spiked samples (sea water and urine) with deviations lower than 10% in all cases. PMID:27566363</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70025445','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70025445"><span id="translatedtitle">Evidence for chlorine recycling - Hydrosphere, biosphere, atmosphere - In a forested wet zone on the Canadian Shield</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Milton, G.M.; Milton, J.C.D.; Schiff, S.; Cook, P.; Kotzer, T.G.; Cecil, L.D.</p> <p>2003-01-01</p> <p>The ability to measure environmental levels of <span class="hlt">36</span><span class="hlt">Cl</span> by Accelerator Mass Spectrometry and 3H by 3He-ingrowth Mass Spectrometry has made it possible to use the pulses of these two isotopes released into the atmosphere during nuclear weapons testing as tracers of Cl and water movement in soils and groundwater. The authors have investigated the movement of these tracers below a forested wet zone, and have found that both are retarded to a differing extent in the near surface because of vegetative uptake and recycling. Adsorption by clay particles, followed by slow release to the groundwater, may also be significant. The data accumulated in this region of near vertical recharge have gone a considerable distance towards explaining the anomalously low concentrations of <span class="hlt">36</span><span class="hlt">Cl</span> measured in the 5 Laurentian Great Lakes, as well as indicating possible mechanisms for large scale Cl- recycling in the atmosphere and biosphere. Identification of the near-term non-conservative behaviour of the Cl- is significant, since such a phenomenon could introduce errors in many watershed calculations, e.g. water residence times, evaporation rates, and mixing calculations. Published by Elsevier Science Ltd.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70020502','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70020502"><span id="translatedtitle">Isotopic composition of ice cores and meltwater from upper fremont glacier and Galena Creek rock glacier, Wyoming</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>DeWayne, Cecil L.; Green, J.R.; Vogt, S.; Michel, R.; Cottrell, G.</p> <p>1998-01-01</p> <p>Meltwater runoff from glaciers can result from various sources, including recent precipitation and melted glacial ice. Determining the origin of the meltwater from glaciers through isotopic analysis can provide information about such things as the character and distribution of ablation on glaciers. A 9.4 m ice core and meltwater were collected in 1995 and 1996 at the glacigenic Galena Creek rock glacier in Wyoming's Absaroka Mountains. Measurements of chlorine-36 (<span class="hlt">36</span><span class="hlt">Cl</span>), tritium (3H), sulphur-35 (35S), and delta oxygen-18 (??18O) were compared to similar measurements from an ice core taken from the Upper Fremont Glacier in the Wind River Range of Wyoming collected in 1991-95. Meltwater samples from three sites on the rock glacier yielded <span class="hlt">36</span><span class="hlt">Cl</span> concentrations that ranged from 2.1 ?? 1.0 X 106 to 5.8??0.3 X 106 atoms/l. The ice-core <span class="hlt">36</span><span class="hlt">Cl</span> concentrations from Galena Creek ranged from 3.4??0.3 X 105 to 1.0??0.1 X 106 atoms/l. Analysis of an ice core from the Upper Fremont Glacier yielded <span class="hlt">36</span><span class="hlt">Cl</span> concentrations of 1.2??0.2 X 106 and 5.2??0.2 X 106 atoms/l for pre- 1940 ice and between 2 X 106 and 3 X 106 atoms/l for post-1980 ice. Purdue's PRIME Lab analyzed the ice from the Upper Fremont Glacier. The highest concentration of <span class="hlt">36</span><span class="hlt">Cl</span> in the ice was 77 ?? 2 X 106 atoms/l and was deposited during the peak of atmospheric nuclear weapons testing in the late 1950s. This is an order of magnitude greater than the largest measured concentration from both the Upper Fremont Glacier ice core that was not affected by weapons testing fallout and the ice core collected from the Galena Creek rock glacier. Tritium concentrations from the rock glacier ranged from 9.2??0.6 to 13.2??0.8 tritium units (TU) in the meltwater to -1.3??1.3 TU in the ice core. Concentrations of 3H in the Upper Fremont Glacier ice core ranged from 0 TU in the ice older than 50 years to 6-12 TU in the ice deposited in the last 10 years. The maximum 3H concentration in ice from the Upper Fremont Glacier deposited in the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/282978','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/282978"><span id="translatedtitle">Shooting stars: Our guide to the early solar system`s formation</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>O`Reilly, J.</p> <p>1995-11-01</p> <p>Plagioclase grains were studied from the Allende meteorite, sample 916, to determine a chronology of events that occurred within the first ten million years of the solar system`s formation. Radiometric dating of the {sup <span class="hlt">26</span>}-<span class="hlt">Al</span>-{sup 26}Mg system was accomplished on the ion microprobe mass spectromer. The excess {sup 26}-Mg in core plagioclase grains of calcium-aluminum rich inclusions (CAIs) provided a time of original condensation for {sup <span class="hlt">26</span>}-<span class="hlt">Al</span> of {approximately}4.55 million years ago, a hundred million years prior to the formation of the planets. This data has been found to correlate with other excess {sup 26}-Mg samples. Measurements of plagioclase in the CAI`s periphery dated 1.52 million years later, suggesting an interesting history of collision and melting.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/6316903','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/6316903"><span id="translatedtitle">Production rates of cosmogenic nuclides in stony meteorites</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Divadeenam, M.; Gabriel, T.A.; Lazareth, O.W.; Spergel, M.S.; Ward, T.E.</p> <p>1989-01-01</p> <p>Monte Carlo calculations of /sup <span class="hlt">26</span>/<span class="hlt">Al</span> and /sup 53/Mn production due to spallation induced by cosmogenic protons in model meteorite composition similar to L Chondrite has yielded predictions which are consistent with the observed decay rates in L Chondrite stony meteorites. The calculated /sup <span class="hlt">26</span>/<span class="hlt">Al</span> production rate (54 dpm/kg) in a 1 m diameter meteorite is within 1/2 S.D. of the mean (49 +- 11 dpm/kg) taken from 100 bulk determinations in L Chondrite samples compiled in Nishiizumi (1987). Similarly calculated average value for /sup 53/Mn (223 dpm/kg) is consistent with one S.D. off the mean in the widely scattered /sup 53/Mn data (362 +- 113 dpm/kg) compiled by Nishiizumi (1987). 9 refs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PhRvC..92c5808D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PhRvC..92c5808D"><span id="translatedtitle">Structure of resonances in the Gamow burning window for the 25Al(p ,γ )26Si reaction in novae</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Doherty, D. T.; Woods, P. J.; Seweryniak, D.; Albers, M.; Ayangeakaa, A. D.; Carpenter, M. P.; Chiara, C. J.; David, H. M.; Harker, J. L.; Janssens, R. V. F.; Kankainen, A.; Lederer, C.; Zhu, S.</p> <p>2015-09-01</p> <p>A γ -ray spectroscopy study of excited states in 26Si has been performed by using the 24Mg(3He ,n ) reaction at a beam energy of 10 MeV. In particular, states have been studied above the proton threshold relevant for burning in the 25Al(p ,γ )26Si reaction in novae. This reaction influences the amount of <span class="hlt">26</span><span class="hlt">Al</span> injected into the interstellar medium by novae, which contributes to the overall flux of cosmic γ -ray emission from <span class="hlt">26</span><span class="hlt">Al</span> observed in satellite missions. The present results point strongly to the existence of a 0+ state at an excitation energy of 5890 keV lying within the Gamow burning window, which raises questions about the existence and properties of another, higher-lying state reported in previous experimental work. The existence of two such states within this excitation energy region cannot be understood within the framework of s d -shell-model calculations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1999Geomo..27...25B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1999Geomo..27...25B"><span id="translatedtitle">Mid-Pleistocene cosmogenic minimum-age limits for pre-Wisconsinan glacial surfaces in southwestern Minnesota and southern Baffin Island: a multiple nuclide approach</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bierman, Paul R.; Marsella, Kimberly A.; Patterson, Carrie; Davis, P. Thompson; Caffee, Marc</p> <p>1999-02-01</p> <p>Paired 10Be and <span class="hlt">26</span><span class="hlt">Al</span> analyses ( n=14) indicate that pre-Wisconsinan, glaciated bedrock surfaces near the northern (Baffin Island) and southern (Minnesota) paleo-margins of the Laurentide Ice Sheet have long and complex histories of cosmic-ray exposure, including significant periods of partial or complete shielding from cosmic rays. Using the ratio, <span class="hlt">26</span><span class="hlt">Al</span>/ 10Be, we calculate that striated outcrops of Sioux Quartzite in southwestern Minnesota (southern margin) were last overrun by ice at least 500,000 years ago. Weathered bedrock tors on the once-glaciated uplands of Baffin Island (northern margin) are eroding no faster than 1.1 m Myr -1, the equivalent of at least 450,000 years of surface and near-surface exposure. Our data demonstrate that exposure ages and erosion rates calculated from single nuclides can underestimate surface stability dramatically because any intermittent burial, and the resultant lowering of nuclide production rates and nuclide abundances, will remain undetected.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70021806','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70021806"><span id="translatedtitle">Mid-Pleistocene cosmogenic minimum-age limits for pre-Wisconsinan glacial surfaces in southwestern Minnesota and southern Baffin Island: A multiple nuclide approach</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Bierman, P.R.; Marsella, K.A.; Patterson, Chris; Davis, P.T.; Caffee, M.</p> <p>1999-01-01</p> <p>Paired 10Be and <span class="hlt">26</span><span class="hlt">Al</span> analyses (n = 14) indicate that pre-Wisconsinan, glaciated bedrock surfaces near the northern (Baffin Island) and southern (Minnesota) paleo-margins of the Laurentide Ice Sheet have long and complex histories of cosmic-ray exposure, including significant periods of partial or complete shielding from cosmic rays. Using the ratio, <span class="hlt">26</span><span class="hlt">Al</span>/10Be, we calculate that striated outcrops of Sioux Quartzite in southwestern Minnesota (southern margin) were last overrun by ice at least 500,000 years ago. Weathered bedrock tors on the once-glaciated uplands of Baffin Island (northern margin) are eroding no faster than 1.1 m Myr-1, the equivalent of at least 450,000 years of surface and near-surface exposure. Our data demonstrate that exposure ages and erosion rates calculated from single nuclides can underestimate surface stability dramatically because any intermittent burial, and the resultant lowering of nuclide production rates and nuclide abundances, will remain undetected.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19780017272','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19780017272"><span id="translatedtitle">Pressureless sintered Sialons with low amounts of sintering aid</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Arias, A.</p> <p>1978-01-01</p> <p>Two Beta prime - Sialons of composition Si2.6Al0.393y0.007O0.4N3.6 and Si2.6Al0.384Y0.014O0.4N3.6 were pressureless sintered from mixtures of Y2O3 and separately milled Beta -Si3N4, AlN, and SiO2. These Sialons had densities of over 98% of theoretical, four-point bend strengths of 460 and 155 MPa at room temperature and 1400 C, respectively, and 1400 C oxidation rates lower than those reported for hot pressed Si3N4 and for a stronger Sialon with 2.5 weight percentage Y2O3.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhRvC..93f4608C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhRvC..93f4608C"><span id="translatedtitle">Cross sections of proton- and neutron-induced reactions by the Liège intranuclear cascade model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chen, Jian; Dong, Tiekuang; Ren, Zhongzhou</p> <p>2016-06-01</p> <p>The purpose of the paper is mainly to test the validity of the Liège intranuclear cascade (INCL) model in calculating the cross sections of proton-induced reactions for cosmogenic nuclei using the newly compiled database of proton cross sections. The model calculations of 3He display the rising tendency of cross sections with the increase of energy, in accordance with the experimental data. Meanwhile, the differences between the theoretical results and experimental data of production cross sections (10Be and <span class="hlt">26</span><span class="hlt">Al</span>) are generally within a factor of 3, meaning that the INCL model works quite well for the proton-induced reactions. Based on the good agreement, we predict the production cross sections of <span class="hlt">26</span><span class="hlt">Al</span> from reactions n + 27Al, n + 28Si, and n + 40Ca and those of 10Be from reactions n + 16O and n + 28Si. The results also show a good agreement with a posteriori excitation functions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/5072672','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/5072672"><span id="translatedtitle">Long-lived light mass element half-lives (A < 125)</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Holden, N.E.</p> <p>1985-01-01</p> <p>Reported values of half-lives of light and intermediate mass elements are evaluated. The evaluation analysis estimates the systematic error and the resulting standard deviation. Recommended values are then presented for tritium, /sup 10/Be, /sup 14/C, /sup <span class="hlt">26</span>/<span class="hlt">Al</span>, /sup 39/Ar, /sup 40/K, /sup 50/V, /sup 53/Mn, /sup 76/Ge, /sup 87/Rb, /sup 92/Nb, /sup 107/Pd, /sup 113/Cd, /sup 115/In, and /sup 123/Te. 106 refs., 15 tabs. (WRF)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/15846340','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15846340"><span id="translatedtitle">Chronology of the early Solar System from chondrule-bearing calcium-aluminium-rich inclusions.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Krot, Alexander N; Yurimoto, Hisayoshi; Hutcheon, Ian D; MacPherson, Glenn J</p> <p>2005-04-21</p> <p>Chondrules and Ca-Al-rich inclusions (CAIs) are high-temperature components of meteorites that formed during transient heating events in the early Solar System. A major unresolved issue is the relative timing of CAI and chondrule formation. From the presence of chondrule fragments in an igneous CAI, it was concluded that some chondrules formed before CAIs (ref. 5). This conclusion is contrary to the presence of relict CAIs inside chondrules, as well as to the higher abundance of <span class="hlt">26</span><span class="hlt">Al</span> in CAIs; both observations indicate that CAIs pre-date chondrules by 1-3 million years (Myr). Here we report that relict chondrule material in the Allende meteorite, composed of olivine and low-calcium pyroxene, occurs in the outer portions of two CAIs and is 16O-poor (Delta17O approximately -1 per thousand to -5 per thousand). Spinel and diopside in the CAI cores are 16O-rich (Delta17O up to -20 per thousand), whereas diopside in their outer zones, as well as melilite and anorthite, are 16O-depleted (Delta17O = -8 per thousand to 2 per thousand). Both chondrule-bearing CAIs are <span class="hlt">26</span><span class="hlt">Al</span>-poor with initial <span class="hlt">26</span><span class="hlt">Al</span>/27Al ratios of (4.7 +/- 1.4) x 10(-6) and <1.2 x 10(-6). We conclude that these CAIs had chondrule material added to them during a re-melting episode approximately 2 Myr after formation of CAIs with the canonical <span class="hlt">26</span><span class="hlt">Al</span>/27Al ratio of 5 x 10(-5).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4326683','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4326683"><span id="translatedtitle">Evidence for nucleosynthetic enrichment of the protosolar molecular cloud core by multiple supernova events</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Schiller, Martin; Paton, Chad; Bizzarro, Martin</p> <p>2015-01-01</p> <p>The presence of isotope heterogeneity of nucleosynthetic origin amongst meteorites and their components provides a record of the diverse stars that contributed matter to the protosolar molecular cloud core. Understanding how and when the solar system’s nucleosynthetic heterogeneity was established and preserved within the solar protoplanetary disk is critical for unraveling the earliest formative stages of the solar system. Here, we report calcium and magnesium isotope measurements of primitive and differentiated meteorites as well as various types of refractory inclusions, including refractory inclusions (CAIs) formed with the canonical <span class="hlt">26</span><span class="hlt">Al</span>/27Al of ~5 × 10−5 (<span class="hlt">26</span><span class="hlt">Al</span> decays to 26Mg with a half-life of ~0.73 Ma) and CAIs that show fractionated and unidentified nuclear effects (FUN-CAIs) to understand the origin of the solar system’s nucleosynthetic heterogeneity. Bulk analyses of primitive and differentiated meteorites along with canonical and FUN-CAIs define correlated, mass-independent variations in 43Ca, 46Ca and 48Ca. Moreover, sequential dissolution experiments of the Ivuna carbonaceous chondrite aimed at identifying the nature and number of presolar carriers of isotope anomalies within primitive meteorites have detected the presence of multiple carriers of the short-lived <span class="hlt">26</span><span class="hlt">Al</span> nuclide as well as carriers of anomalous and uncorrelated 43Ca, 46Ca and 48Ca compositions, which requires input from multiple and recent supernovae sources. We infer that the solar system’s correlated nucleosynthetic variability reflects unmixing of old, galactically-inherited homogeneous dust from a new, supernovae-derived dust component formed shortly prior to or during the evolution of the giant molecular cloud parental to the protosolar molecular cloud core. This implies that similarly to 43Ca, 46Ca and 48Ca, the short-lived <span class="hlt">26</span><span class="hlt">Al</span> nuclide was heterogeneously distributed in the inner solar system at the time of CAI formation. PMID:25684790</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19008430','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19008430"><span id="translatedtitle">Comment on "ancient asteroids enriched in refractory inclusions".</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hezel, Dominik C; Russell, Sara S</p> <p>2008-11-14</p> <p>Sunshine et al. (Reports, 25 April 2008, p. 514) reported that certain asteroids contain 30 +/- 10 volume percent calcium- and aluminum-rich inclusions (CAIs). We contend that the amount of CAIs in CV chondrites is two to three times as low as the 10 volume percent assumed by the authors; thus, we question whether the CAI-rich bodies they studied are indeed older than known asteroids or formed before the injection of (<span class="hlt">26</span>)<span class="hlt">Al</span> into the solar nebula.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19950061986&hterms=Nucleosynthesis&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DNucleosynthesis','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19950061986&hterms=Nucleosynthesis&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DNucleosynthesis"><span id="translatedtitle">Nucleosynthesis in AGB stars: Observation of Mg-25 and Mg-26 in IRC+10216 and possible detection of Al-26</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Guelin, M.; Forestini, M.; Valiron, P.; Ziurys, L. M.; Anderson, M. A.; Cernicharo, J.; Kahane, C.</p> <p>1995-01-01</p> <p>We report the detection in the circumstellar envelope IRC+10216 of millimeter lines of the rare isotopomers (25)MgNC and (26)MgNC, as well as of a line at 234433 MHz, which could be the J= 7-6 transition of (<span class="hlt">26</span>)<span class="hlt">Al</span>F (an alternate, although less likely identified would be the J= 9-8 transition of NaF). The derived Mg-24:Mg-25:Mg-26 isotopic abundance ratios (78 : 11+/- 1 : 11 +/-1) are consistent with the solar system values (79.0:10.0:11.0), following Anders & Grevesse 1989). According to new calculations of evolutionary models of 3 solar mass and 5 solar mass asymptotic giant branch (AGB) stars, these ratios and the previously measured N, O and Si isotopic ratios imply that the central star had an initial mass 3 solar mass (less than or equal to M(sub *, ini) less than 5 solar mass and has already experienced many 3rd dredge-up events. From this, it can be predicted that the Al-<span class="hlt">26</span>/<span class="hlt">Al</span>-27 isotopics ratio lies between 0.01 and 0.08; in fact, the value derived in the case that U234433 arises from (<span class="hlt">26</span>)<span class="hlt">Al</span>F is Al-<span class="hlt">26</span>/<span class="hlt">Al</span>-27 = 0.04. The identification of the (25)MgNC and (26)MgNC lines was made possible by ab-initio quantum mechanical calculations of the molecule geometrical structure. It was confirmed through millimeter-wave laboratory measurements. The quantum mechanical calculations are briefly described and the laboratory results presented in some detail. The rotation constants B, D, H and the spin-rotation constant gamma of (25)MgNC and (26)MgNC are determined from a fit of laboratory and astronomical data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/414861','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/414861"><span id="translatedtitle">Revised activation estimates for silicon carbide</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Heinisch, H.L.; Cheng, E.T.; Mann, F.M.</p> <p>1996-10-01</p> <p>Recent progress in nuclear data development for fusion energy systems includes a reevaluation of neutron activation cross sections for silicon and aluminum. Activation calculations using the newly compiled Fusion Evaluated Nuclear Data Library result in calculated levels of {sup <span class="hlt">26</span>}<span class="hlt">Al</span> in irradiated silicon that are about an order of magnitude lower than the earlier calculated values. Thus, according to the latest internationally accepted nuclear data, SiC is much more attractive as a low activation material, even in first wall applications.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFMDI41B..04S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFMDI41B..04S"><span id="translatedtitle">Thermal Evolution And Core Formation In Planetesimals And Planetary Embryos</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sramek, O.; Labrosse, S.; Ricard, Y. R.; milelli, L.</p> <p>2011-12-01</p> <p>Recent dating of iron meteorites shows that they were formed almost as early as the oldest known objects of the solar system, the CAIs. Moreover, several meteorites show a magnetization that is thought to originate from the action of a dynamo at the early stages of the planetesimals evolution. Core formation requires melting of the metal which then can percolate toward the center, providing the solid matrix deforms and compacts. The energy source for melting of the metal comes from a combination of short lived radionuclides, mostly <span class="hlt">26</span><span class="hlt">Al</span>, and accretion energy for bodies larger than about 1000 km. We considered a suite of numerical calculations solving for the coupled problem of thermal evolution, melt percolation and matrix compaction, systematically exploring the different accretion histories, final body size and initial concentration in <span class="hlt">26</span><span class="hlt">Al</span>. Our model handles simultaneously metal and silicates in both solid and liquid states. Depending on the accretion rate, melting occurs from the center outward, in a shallow outer shell progressing inward, or in the two locations. Segregation of the protocore decreases the efficiency of radiogenic heating by confining the <span class="hlt">26</span><span class="hlt">Al</span> in the outer silicate shell. Various types of planetesimals partly differentiated and sometimes differentiated in multiple metal-silicate layers can be obtained. We discuss the thermal profiles of the accreted bodies in relation to possible early dynamo action as evidenced by remanent magnetization observed on some meteorite samples.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5542553','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5542553"><span id="translatedtitle">Correlated study of initial sup 87 Sr/ sup 86 Sr and Al-Mg isotopic systematics and petrologic properties in a suite of refractory inclusion from the Allende meteorite</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Podosek, F.A.; Zinner, E.K.; Lundeberg, L.L.; Brannon, J.C.; Fahey, A.J. );