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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 (26Al, 36Cl, 3He, and 21Ne)

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

    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.

  2. 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

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

    2016-02-01

    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 ((26)Al and (36)Cl) and stable ((3)He and (21)Ne) nuclides in quartz, dolomite/calcite, sanidine, and diopside. The obtained results suggest that there is accordance in the values obtained by applying (26)Al, (36)Cl, and (21)Ne 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 (205)Pb derived from pp-neutrino and fast cosmic-ray muons, respectively, which is an important prerequisite for the LOREX experiment.

  3. 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

  4. The initial 41Ca/40Ca ratios in two type A Ca-Al-rich inclusions: Implications for the origin of short-lived 41Ca

    NASA Astrophysics Data System (ADS)

    Liu, Ming-Chang

    2017-03-01

    This paper reports new 41Ca-41K isotopic data for two Type A CAIs, NWA 3118 #1Nb (Compact Type A) and Vigarano 3138 F8 (Fluffy Type A), from reduced CV3 chondrites. The NWA CAI is found to have carried live 41Ca at the level of (4.6 ± 1.9) ×10-9 , consistent with the proposed Solar System initial 41Ca /40Ca = 4.2 ×10-9 by Liu et al. (2012a). On the other hand, the Vigarano CAI does not have resolvable radiogenic 41K excesses that can be attributed to the decay of 41Ca. Combined with the 26Al data that have been reported for these two CAIs, we infer that the 41Ca distribution was not homogeneous when 26Al was widespread at the canonical level of 26Al /27Al = 5.2 ×10-5 . Such a 41Ca heterogeneity can be understood under two astrophysical contexts: in situ charged particle irradiation by the protoSun in the solar nebula that had inherited some baseline 10Be abundance from the molecular cloud, and Solar System formation in a molecular cloud enriched in 26Al and 41Ca contaminated by massive star winds. That said, more high quality 41Ca data are still needed to better understand the origin of this radionuclide.

  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. Problems of contamination in 36Cl studies

    NASA Astrophysics Data System (ADS)

    Bird, J. R.; Shahgholi, N.; Jenkinson, A.; Smith, A.; Fifield, L. K.; Ophel, T.; Allan, G.

    1990-12-01

    The joint ANSTO/ANU 36Cl program has now measured more than 700 samples from many different locations. During the course of this work, a variety of contamination problems have affected a small number of results which have provided valuable information on the effects of ion source cross-talk, sample preparation and storage procedures and sources of high- 36Cl material. A sample of Weeks Island halite is processed along with every batch of field samples and the observed ratio provides a clear distinction between normal batches and those subject to contamination. Over three years, the long-term average ratio of {36Cl}/{Cl} for normal halite samples is (1 ± 1) × 10 -15. The sample handling procedures developed during the course of this work provide a useful guide to the techniques that must be used to achieve the sensitivity limits which are potentially available using AMS.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

    1987-12-31

    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 {sup 36}Cl/Cl ratio 0.5 m below the surface. The structure of the {sup 36}Cl bomb pulse at the other location was much more complex, and the 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.

  13. 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.

  14. 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.

  15. {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.

  16. 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.

  17. 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.

  18. 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

  19. COLLATERAL EFFECTS ON SOLAR NEBULA OXYGEN ISOTOPES DUE TO INJECTION OF {sup 26}Al BY A NEARBY SUPERNOVA

    SciTech Connect

    Ellinger, Carola I.; Young, Patrick A.; Desch, Steven J.

    2010-12-20

    Injection of material from a core-collapse supernova into the solar system's already-formed disk is one proposed mechanism for producing the short-lived radionuclides, such as {sup 26}Al and {sup 41}Ca, inferred from isotopic studies of meteorites to have existed in the solar nebula. This hypothesis has recently been challenged on the basis that the injection of enough supernova material to match the meteoritic abundances of {sup 26}Al and {sup 41}Ca would produce large, measurable, and unobserved collateral effects on oxygen isotopes. Here we calculate again the shifts in oxygen isotopes due to the injection of supernova material in the solar nebula, using a variety of nucleosynthetic conditions of our own progenitor explosions. Unlike previous studies of this type, we also consider the effect of non-homogeneity in abundance distribution of the nucleosynthesis products after the explosion. We calculate the shifts in oxygen isotopes due to the injection of sufficient supernova material to produce the meteoritic abundances of {sup 26}Al and {sup 41}Ca, and analyze the predicted shifts in detail for compatibility with meteoritic data. We find that the range in possible isotopic shifts is considerable and sensitive to parameters such as progenitor mass and anisotropy of the explosion; however, a small number of compatible scenarios do exist. Because of the wide range of outcomes and the sensitivity of isotopic yields to assumed conditions, it is difficult to constrain the supernova that may have led to the injection of {sup 26}Al in the solar nebula. Conversely, we argue that the existence of viable counterexamples demonstrates that it is premature to use oxygen isotopes to rule out the injection of {sup 26}Al and {sup 41}Ca into the solar nebula protoplanetary disk by a nearby supernova.

  20. Measuring astrophysically relevant 36Cl production cross sections

    NASA Astrophysics Data System (ADS)

    Anderson, Tyler; Skulski, Michael; Ostdiek, Karen; Lu, Wenting; Clark, Adam; Nelson, Austin; Beard, Mary; Collon, Philippe

    2016-09-01

    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 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 33S(α,p)36Cl cross section at various energies in the range of 0.70-2.42 MeV/A, and found them to be systematically under predicted by Hauser-Feshbach statistical model codes TALYS and NON-SMOKER, highlighting the need for more empirical data for these cross sections. Recent results of the re-measurement of the 33S(α,p)36Cl reaction, providing greater coverage of the same energy range as Bowers et al., will be presented. Future plans for measurement of other 36Cl producing reactions will also be discussed.

  1. 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.

  2. 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

  3. Half life of /sup 26/Al

    SciTech Connect

    Norris, T.L.; Gancarz, A.J.; Rokop, D.J.; Thomas, K.W.

    1983-01-01

    The half-life of /sup 26/Al has been redetermined because of suggestions of an error in the accepted value based on its use in calculating /sup 21/Ne production rates from cosmic rays in meteorites. Two solutions of /sup 26/Al were analyzed for the specific radioactivity and mass spectrometric determination of the /sup 26/Al concentration. The half-life obtained for /sup 26/Al was 7.05 x 10/sup 5/ years +- 3.7% at the two sigma level. This is identical to the accepted value of 7.16 x 10/sup 5/ years and indicates that problems with the /sup 21/Ne production rate is not due to an erroneous half-life.

  4. 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

  5. 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).

  6. High spin γ -ray spectroscopy in 41Ca

    NASA Astrophysics Data System (ADS)

    Bhattacharjee, R.; Samanta, S.; Das, S.; Bhattacharjee, S. S.; Raut, R.; Ghugre, S. S.; Sinha, A. K.; Garg, U.; Chakrabarti, R.; Mukhopadhyay, S.; Dhal, A.; Singh, R. P.; Madhavan, N.; Muralithar, S.

    2016-11-01

    High spin states in 41Ca have been investigated by using γ -ray spectroscopic techniques following the 27Al(16O,p n )41Ca fusion-evaporation reaction. Around twelve new transitions belonging to 41Ca have been observed and placed in the level scheme, which now has been extended up to Ex˜9 MeV. The spin-parity assignments for the observed levels were arrived at following the analysis of both the coincidence intensity anisotropies and linear polarization measurements. The established 5p-4h band was extended up to Jπ=19 /2- . The observations of Doppler shape and shifts facilitated the estimation of the level lifetimes by using the Doppler shift attenuation method. The lifetimes were validated with respect to previous measurements and lifetime of a few levels has been arrived at for the first time. Shell-model calculations were carried out to explain the observed level structure of the nucleus and are indicative of both single-particle and collective degrees of freedom in this N ˜Z ˜20 nucleus.

  7. On the Production of 36Cl by High-Energy Particles in Thin- and Thick- Target Experiments

    NASA Astrophysics Data System (ADS)

    Schiekel, Th.; Herpers, U.; Sudbrock, F.; Gloris, M.; Leya, I.; Michel, R.; Synal, H.-A.; Suter, M.

    1995-09-01

    Knowledge about the production of cosmogenic nuclides in meteorites, planetary surfaces and cosmic dust is elementary for various cosmophysical studies. Completely known it would contain information about the constancy and the spectral distribution of cosmic radiation and it would allow to decipher the irradiation history of matter under the condition of solar and galactic cosmic ray exposure. Cosmic ray particle interactions with matter can be described by a thin-target approach. In this case integral excitation functions for the main target elements have to be combined with depth dependent spectra of primary and secondary particles, see for instance [1]. On the other hand thick-target simulation experiments have been accomplished [2,3] from which production rates can be directly determined. Both approaches have been investigated and successfully validated for short- as well as for long-lived nuclides, e.g ^10Be and ^26Al [3]. Now extending our investigations on the nuclide ^36Cl irradiation experiments with initial proton energies ranging from 45 MeV up to 2600 MeV have been carried out using the "stacked-foil-technique". We have yet determined integral excitation functions for proton induced production of ^36Cl from the most relevant as well as for some minor target elements in meteorites (e.g. Ca, Ti, V, Mn, Fe, Ni, Co, Cu) providing necessary data for the thin-target approach. ^36Cl in the individual targets has been measured via the ultrasensitive accelerator mass spectrometry after a radiochemical separation. For a validation of the above mentioned model calculations based on the thin-target approach by Michel et al. [1], the depth dependent elemental production rates of ^36Cl from the main target elements have been measured in two artificial meteorites made out of gabbro and iron (radii 25 cm and 10 cm respectively) irradiated isotropically with 1,6 GeV protons [3,4]. The theoretical calculations agree reasonably well with our experimental results for the

  8. 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.

  9. {sup 26}Al AND THE FORMATION OF THE SOLAR SYSTEM FROM A MOLECULAR CLOUD CONTAMINATED BY WOLF-RAYET WINDS

    SciTech Connect

    Gaidos, Eric; Krot, Alexander N.; Williams, Jonathan P.; Raymond, Sean N. E-mail: sasha@higp.hawaii.edu E-mail: sean.raymond@colorado.edu

    2009-05-10

    In agreement with previous work, we show that the presence of the short-lived radionuclide (SLR) {sup 26}Al in the early solar system was unlikely (less than 2% a priori probability) to be the result of direct introduction of supernova (SN) ejecta into the gaseous disk during the Class II stage of protosolar evolution. We also show that Bondi-Hoyle accretion of any contaminated residual gas from the Sun's natal star cluster contributed negligible {sup 26}Al to the primordial solar system. Our calculations are consistent with the absence of the oxygen isotopic signature expected with any late introduction of SN ejecta into the protoplanetary disk. Instead, the presence of {sup 26}Al in the oldest solar system solids (calcium-aluminum-rich inclusions (CAIs)) and its apparent uniform distribution with the inferred canonical {sup 26}Al/{sup 27}Al ratio of (4.5-5) x 10{sup -5} support the inheritance of {sup 26}Al from the Sun's parent giant molecular cloud. We propose that this radionuclide originated in a prior generation of massive stars that formed in the same molecular cloud and contaminated that cloud by Wolf-Rayet winds. We calculated the Galactic distribution of {sup 26}Al/{sup 27}Al ratios that arise from such contamination using the established embedded cluster mass and stellar initial mass functions, published nucleosynthetic yields from the winds of massive stars, and by assuming rapid and uniform mixing into the cloud. Although our model predicts that the majority of stellar systems contain no {sup 26}Al from massive stars, and that the a priori probability that the {sup 26}Al/{sup 27}Al ratio will reach or exceed the canonical solar system value is only {approx}6%, the maximum in the distribution of nonzero values is close to the canonical {sup 26}Al/{sup 27}Al ratio. We find that the Sun most likely formed 4-5 million years (Myr) after the massive stars that were the source of {sup 26}Al. Furthermore, our model can explain the initial solar system

  10. Estimation of groundwater residence time using the 36Cl bomb pulse.

    PubMed

    Tosaki, Yuki; Tase, Norio; Sasa, Kimikazu; Takahashi, Tsutomu; Nagashima, Yasuo

    2011-01-01

    We propose a methodology for estimating the residence time of groundwater based on bomb-produced (36)Cl. Water samples were collected from 28 springs and 2 flowing wells located around Mt. Fuji, Central Japan. (36)Cl/Cl ratios in the water samples, determined by accelerator mass spectrometry (AMS), were between 43 × 10(-15) and 412 × 10(-15). A reference time series of the above-background (i.e., bomb-derived) (36)Cl concentration was constructed by linearly scaling the background-corrected Dye-3 data according to the estimated total bomb-produced (36)Cl fallout in the Mt. Fuji area. Assuming piston flow transport, estimates of residence time were obtained by comparing the measured bomb-derived (36)Cl concentrations in spring water with the reference curve. The distribution of (36)Cl-based residence times is basically consistent with that of tritium-based estimates calculated from data presented in previous studies, although the estimated residence times differ between the two tracers. This discrepancy may reflect chlorine recycling via vegetation or the relatively small change in fallout rate, approximately since 1975, which would give rise to large uncertainties in (36)Cl-based estimates of recharge for the period, approximately since 1975. Given the estimated ages for groundwater from flowing wells, dating based on a (36)Cl bomb pulse may be more reliable and sensitive for groundwater recharged before 1975, back as far as the mid-1950s.

  11. Application of 36Cl as a dating tool for modern groundwater

    NASA Astrophysics Data System (ADS)

    Tosaki, Yuki; Tase, Norio; Massmann, Gudrun; Nagashima, Yasuo; Seki, Riki; Takahashi, Tsutomu; Sasa, Kimikazu; Sueki, Keisuke; Matsuhiro, Takeshi; Miura, Taichi; Bessho, Kotaro; Matsumura, Hiroshi; He, Ming

    2007-06-01

    The 36Cl/Cl ratios of groundwater samples were measured by accelerator mass spectrometry (AMS) in order to investigate the potential use of 36Cl as a dating tool for modern groundwater. Groundwater samples were obtained from several piezometers in the Oderbruch in northeastern Germany. The shallow confined aquifer of the area is mainly recharged by the infiltration from the River Oder. From the results of measurements, the pre-bomb and the recent background 36Cl/Cl ratios in the basin of the Oder were estimated to be 7-9 × 10-14. The 36Cl fallout values estimated from the 36Cl/Cl ratios of the Oderbruch samples, which were dated by the 3H/3He method, show good agreement with Dye-3 ice core data. These results suggest that the distribution of 36Cl in groundwaters reflects the influence of the 36Cl bomb pulse. This, in turn, suggests that the distribution of 36Cl/Cl in modern groundwaters could reveal groundwater ages and flow systems in a region.

  12. 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.

  13. 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.

  14. 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

  15. 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.

  16. Ultra-trace analysis of 36Cl by accelerator mass spectrometry: an interlaboratory study.

    PubMed

    Merchel, S; Bremser, W; Alfimov, V; Arnold, M; Aumaître, G; Benedetti, L; Bourlès, D L; Caffee, M; Fifield, L K; Finkel, R C; Freeman, S P H T; Martschini, M; Matsushi, Y; Rood, D H; Sasa, K; Steier, P; Takahashi, T; Tamari, M; Tims, S G; Tosaki, Y; Wilcken, K M; Xu, S

    2011-07-01

    A first international (36)Cl interlaboratory comparison has been initiated. Evaluation of the final results of the eight participating accelerator mass spectrometry (AMS) laboratories on three synthetic AgCl samples with (36)Cl/Cl ratios at the 10(-11), 10(-12), and 10(-13) level shows no difference in the sense of simple statistical significance. However, more detailed statistical analyses demonstrate certain interlaboratory bias and underestimation of uncertainties by some laboratories. Following subsequent remeasurement and reanalysis of the data from some AMS facilities, the round-robin data indicate that (36)Cl/Cl data from two individual AMS laboratories can differ by up to 17%. Thus, the demand for further work on harmonising the (36)Cl-system on a worldwide scale and enlarging the improvement of measurements is obvious.

  17. Interaction of (3)H(+) (as HTO) and (36)Cl(-) (as Na(36)Cl) with crushed granite and corresponding fracture infill material investigated in column experiments.

    PubMed

    Štamberg, K; Palágyi, Š; Videnská, K; Havlová, V

    The transport of (3)H(+) (as HTO) and (36)Cl(-) (as Na(36)Cl) was investigated in the dynamic system, i.e., in the columns filled with crushed pure granite and fracture infill of various grain sizes. The aim of column experiments was to determine important transport parameter, such as the retardation, respectively distribution coefficients, Peclet numbers and hydrodynamic dispersion coefficients. Furthermore, the research was focused to quantification of the effect of grain size on migration of studied radionuclides. The experimental breakthrough curves were fitted by a model based on the erfc-function, assuming a linear reversible equilibrium sorption/desorption isotherm, and the above mentioned transport parameters were determined. The results showed that influence of grain size on sorption of (3)H(+) and (36)Cl(-) was negligible. Retardation and distribution coefficients of both tracers converged to one and zero, respectively, in case of all fractions of crushed granite and infill material. Generally, the presumed ion exclusion of (36)Cl in anionic form was proved under given conditions, only very weak one seems to exist in a case of infill material. In principal, both radionuclides behaved as non-sorbing, conservative tracers. On the other hand, the influence of grain size on Peclet numbers value and on dispersion coefficient was observed for both crystalline materials, namely in agreement with theoretical suppositions that the values of Peclet numbers decrease with increasing grain size and values of dispersion coefficient increase.

  18. Bomb-test 36Cl measurements in Vostok snow (Antarctica) and the use of 36Cl as a dating tool for deep ice cores

    NASA Astrophysics Data System (ADS)

    Delmas, R. J.; Beer, J.; Synal, H.-A.; Muscheler, R.; Petit, J.-R.; Pourchet, M.

    2004-11-01

    A large pulse of atmospheric 36Cl generated by a limited number of nuclear tests peaked in the late 1950s to early 1960s. The corresponding enhanced 36Cl deposition is seen in various glaciological archives in the Northern Hemisphere. The profile of the bomb spike recorded in firn layers at Vostok Station, central East Antarctica, has been measured by employing accelerator mass spectrometry (AMS). The records obtained from two well-dated data sets collected in snow pits in 1997 and 1998 show a broad 36Cl peak, beginning as early as the 1940s and reaching its maximum in the 1960s. The signal is followed by a long-lasting tail up to the surface. This pattern is totally unexpected. We show that the results, unlike the Greenland data, can be explained by a mobility of HCl in the Antarctic firn. This experiment demonstrates the instability of gaseous Cl- deposits, a phenomenon which has important implications for the use of natural cosmogenic 36Cl radionuclides as a reliable dating tool for deep ice cores from low-accumulation areas. However, during glacial times, under favourable atmospheric chemistry conditions this dating method may still be applicable. Snow metamorphism and ventilation are assumed to be the two main physical processes responsible for the observed patterns.

  19. 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.

  20. Cosmogenic /sup 36/Cl production rates in meteorites and the lunar surface

    SciTech Connect

    Nishiizumi, K.; Kubik, P.W.; Elmore, D.; Reedy, R.C.; Arnold, J.R.

    1988-01-01

    Activity-versus-depth profiles of cosmic-ray-produced /sup 36/Cl were measured in metal from two cores each in the St. Severin and Jilin chondrites and in lunar core 15008. Production of /sup 36/Cl in these samples range from high-energy reactions with Fe and Ni to low-energy reactions with Ca and K and possibly neutron-capture reactions with /sup 35/Cl. The cross sections used in the Reedy-Arnold model for neutron-induced reactions were adjusted to get production rates that fit the measured /sup 36/Cl activities in St. Severin metal and in the lunar soil of core 15008. The /sup 36/Cl in metal from St. Severin has a fairly flat activity-versus-depth profile, unlike most other cosmogenic nuclides in bulk samples from St. Severin, which increase in concentration with depth. In metal from Jilin, a decrease in /sup 36/Cl was observed near its center. The length of Jilin's most recent cosmic-ray exposure was /approximately/0.5 My. Lunar core 15008 has an excess in /sup 36/Cl of about 4 dpm/kg near its surface that was produced by solar-proton-induced reactions. The calculated production rates are consistent with these measured trends in 15008. 39 refs., 4 figs., 3 tabs.

  1. Transplacental passage of 26Al from pregnant rats to fetuses and 26Al transfer through maternal milk to suckling rats

    NASA Astrophysics Data System (ADS)

    Yumoto, S.; Nagai, H.; Matsuzaki, H.; Kobayashi, T.; Tada, W.; Ohki, Y.; Kakimi, S.; Kobayashi, K.

    2000-10-01

    Aluminium (Al) is toxic to the growth of fetuses and sucklings. However, the incorporation of Al into fetuses and sucklings in the periods of gestation and lactation has not been well clarified because Al lacks a suitable isotope for a tracer experiment. In this study, we used 26Al (a radioisotope of Al with half-life of 716,000 yr) as a tracer, and measured 26Al incorporation into fetuses and sucklings by accelerator mass spectrometry (AMS). To investigate Al incorporation into fetuses through transplacental passage, 26Al ( 26AlCl 3) was subcutaneously injected into pregnant rats on day 15 of gestation. 26Al was also subcutaneoulsy injected into lactating rats from day 1 to day 20 postpartum. By day 20 of gestation, 0.2% of the 26Al injected into a pregnant rat had been transferred to the fetuses, and 26Al was detected in the brain and liver of the fetuses. On day 9 postpartum, high levels of 26Al were demonstrated in the brain, liver, kidneys and blood of suckling rats. It is concluded that 26Al subcutaneously injected into pregnant rats and/or lactating rats is incorporated into their offspring through transplacental passage and/or maternal milk.

  2. 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

  3. 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.

  4. 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.

  5. Radioactive 26Al from massive stars in the Galaxy.

    PubMed

    Diehl, Roland; Halloin, Hubert; Kretschmer, Karsten; Lichti, Giselher G; Schönfelder, Volker; Strong, Andrew W; von Kienlin, Andreas; Wang, Wei; Jean, Pierre; Knödlseder, Jürgen; Roques, Jean-Pierre; Weidenspointner, Georg; Schanne, Stephane; Hartmann, Dieter H; Winkler, Christoph; Wunderer, Cornelia

    2006-01-05

    Gamma-rays from radioactive 26Al (half-life approximately 7.2 x 10(5) years) provide a 'snapshot' view of continuing nucleosynthesis in the Galaxy. The Galaxy is relatively transparent to such gamma-rays, and emission has been found concentrated along its plane. This led to the conclusion that massive stars throughout the Galaxy dominate the production of 26Al. On the other hand, meteoritic data show evidence for locally produced 26Al, perhaps from spallation reactions in the protosolar disk. Furthermore, prominent gamma-ray emission from the Cygnus region suggests that a substantial fraction of Galactic 26Al could originate in localized star-forming regions. Here we report high spectral resolution measurements of 26Al emission at 1808.65 keV, which demonstrate that the 26Al source regions corotate with the Galaxy, supporting its Galaxy-wide origin. We determine a present-day equilibrium mass of 2.8 (+/- 0.8) solar masses of 26Al. We use this to determine that the frequency of core collapse (that is, type Ib/c and type II) supernovae is 1.9 (+/- 1.1) events per century.

  6. ^26Al Beam Production and its Application to Nuclear Astrophysics

    NASA Astrophysics Data System (ADS)

    Richard, Brad

    2012-10-01

    Presumably produced during the supernova stage of stellar evolution, ^26Al offers unique opportunities to better understand the processes of nucleosynthesis occurring in pre-SN phases of stellar evolution and within the Galactic disk. When decaying to ^26Mg, ^26Al emits a unique 1.8MeV gamma ray, detectable by satellite telescopes. The production and destruction pathways of ^26Al is a key portion of understanding the on-going stellar nucleosynthesis. In order to measure the cross-section of ^26Al(n, p) ^26Mg at the astrophysical relevant energies, an indirect method, called the Trojan Horse Method(THM), is utilized. The THM allows the study of neutron induced reactions at astrophysical energies via the d break-up. This method requires the three-body cross section for the ^26Al(d, p ^26Mg)H reaction to be measured at a beam of 60 MeV. This requires that the ^26Al secondary beam is produced by the MARS facility at Cyclotron institute of Texas A&M University from a primary ^26Mg beam (E 16MeV/u) impinging on a H2 target. ^26Al beam was then degraded to 2.25MeV/u energy by means of a Beryllium foil. The obtained results will be shown and discussed in details together with the features of the obtained intense and pure beam.

  7. 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.

  8. Vertical groundwater flow estimated from the bomb pulse of 36Cl and tritiogenic 3He

    NASA Astrophysics Data System (ADS)

    Mahara, Y.; Ohta, T.

    2011-12-01

    The boring well was approximately excavated to 400 m depth from the ground surface on the tableland in the Central Shimokita Peninsula, Japan. Collecting pore-water, some fresh boring cores were sampled on the site during the excavation of borehole. Samples of groundwater were collected by using the sampling device with the water inflating packer system to protect various contaminations, after excavating the borehole. The atmospheric maximum concentration in bomb pulse in the northern hemisphere was reported to observe in 1955 for 36Cl and in 1963 for 3H, respectively. Since the half-life of 36Cl is much longer than 3H, the decay loss of 36Cl was negligible small for a short time until sampling groundwater in 2001 and 2003. On the other hand, the half-life of 3H is very short compared with that of 36Cl. Most of 3H was converted into the tritiogenic 3He in groundwater for the past 38 years after rainwater infiltrating toward the groundwater table. Profiles of dissolved 4He concentration, tritiogenic 3He and 36Cl/Cl ratio were observed in groundwater of the borehole. The total dissolved 4He concentration ranged from 5.8×10-8 at the ground surface to 7.5×10-8 ccSTP/g at the depth of 200 m below the ground surface and it was almost equilibrated with the atmospheric 4He in pore-water (Fig. 1). The bomb pulses of tritiogenic 3He and 36Cl were left from the depth of 101 m below the ground surface to the depth of 132 m, respectively (Figs. 2 and 3). There was a slight difference in the location between the bomb pulse of 36Cl and that of tritiogenic 3He. The downward flow velocity of groundwater were simply estimated to be 2.8 m/y from the marked position of bomb pulse in the profile of 36Cl/Cl ratio and to be 2.7 m/y from the position of the bomb pulse peak of tritiogenic 3He, separately. These two rough estimations were good agreed with each other. The estimation suggests that the vertical flow of groundwater on the tableland is approximated with the downward piston

  9. 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.

  10. Nucleogenic 36Cl, 236U and 239Pu in uranium ores

    NASA Astrophysics Data System (ADS)

    Wilcken, K. M.; Fifield, L. K.; Barrows, T. T.; Tims, S. G.; Gladkis, L. G.

    2008-08-01

    The nucleogenic isotopes 36Cl, 236U and 239Pu are produced naturally in subsurface environments via neutron capture of thermal and epithermal neutrons. Concentrations are, however, very low and accelerator mass spectrometry (AMS) is required for quantitative measurements. A particular challenge is presented by the measurement of 236U/ 238U ratios down to the level of 10 -13 that is expected from rocks with low uranium concentration. Here, we present the AMS methodology that has been developed at the ANU for measuring 236U/ 238U ratios at this level. The more established methodologies for 36Cl and 239Pu measurements are also summarised. These capabilities are then used to characterize the 36Cl, 236U and 239Pu concentrations in a range of uranium ores. A simple model of the neutron production and capture processes in subsurface environments has been developed and is presented. It is shown that nucleogenic 36Cl, 236U and 239Pu can be used to determine both thermal and epithermal neutron fluxes in subsurface environments. Potential applications include uranium exploration and monitoring of the environmental impact of uranium mining.

  11. Implications of halide leaching on 36Cl studies at Yucca Mountain, Nevada

    NASA Astrophysics Data System (ADS)

    Lu, Guoping; Sonnenthal, Eric L.; Bodvarsson, Gudmundur S.

    2003-12-01

    Chlorine 36 was generated from nuclear tests in the 1950s and 1960s and has been used to identify fast flow paths at Yucca Mountain, the proposed repository for high-level nuclear waste [, 1997, 1998]. Bomb pulse 36Cl, brought into the subsurface by infiltrating rainwater, presumably resides along fracture surfaces because of the extremely low rock matrix permeability. However, leaching a rock sample to extract this salt inevitably extracts pore water chloride (Cl) and rock matrix chloride, thereby making it difficult to obtain reproducible measurements or detect the specific bomb pulse signatures. Complexities introduced by these sources of older chloride include dilution of bomb pulse 36Cl/Cl ratios for samples from strata with a high Cl concentration, variations in measured ratios as a function of leaching time, rock chip size, and the differing effects of active leaching from those of passive leaching. This work provides both a conceptual model and a mathematical solution for the leaching processes and examines the role of sample leaching in the 36Cl studies of Yucca Mountain rocks. An analytical solution is derived for the diffusion of Cl and 36Cl in composite media (rock matrix and water) to accommodate variable diffusivity. This solution is subsequently used to develop a leaching model that takes into account bomb pulse signal, matrix pore water, and relatively hard to leach components (isolated fluid inclusion and mineral boundary salts). The model is then applied to samples from stratigraphic units at Yucca Mountain to obtain leachate concentrations from different setup methods (protocols), including duration, chip size, and gravitational settling of the water-rock mixture. The model results show that the probability of detecting a 36Cl/Cl bomb pulse signal is severely diminished under longer leaching times and smaller rock fragment sizes and that leaching times of 1 to 10 hours are most likely to be successful in detecting a bomb pulse signal. Bomb pulse

  12. 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...

  13. 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.

  14. 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.

  15. Depth dependence of soil carbonate accumulation based on cosmogenic 36Cl dating

    NASA Astrophysics Data System (ADS)

    Liu, Beiling; Phillips, Fred M.; Elmore, David; Sharma, Pankaj

    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 36Cl-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 36Cl-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.

  16. 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.

  17. Human calcium metabolism including bone resorption measured with 41Ca tracer

    NASA Astrophysics Data System (ADS)

    Freeman, Stewart P. H. T.; King, Janet C.; Vieira, Nancy E.; Woodhouse, Leslie R.; Yergey, Alfred L.

    1997-03-01

    Accelerator mass spectrometry is so sensitive to small quantities of 41Ca 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, 41Ca 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.

  18. Leaching of /sup 14/C and /sup 36/Cl from Hanford reactor graphite

    SciTech Connect

    Gray, W.J.; Morgan, W.C.

    1988-12-01

    The leach rates of /sup 14C/ and /sup 36Cl/ were measured on solid cylindrical samples of graphite prepared from a bar retrieved from one of the surplus Hanford production reactors. Static leach tests were conducted in deionized water and Hanford ground water at temperatures of 20/degree/C to 90/degree/C for 8 weeks. The graphite samples were completely submerged in the leachant, and the entire volume of leachant was changed and analyzed weekly. The leach rates of both /sup 14C/ and /sup 36Cl/ decreased with time and appeared to approach steady-state values that were independent of temperature in the case of /sup 36Cl/ but decreased with temperature in the case of /sup 14C/. Both radionuclides leached more slowly in Hanford ground water. The data are compared with previously measured and estimated leach rates. Implications of the data regarding possible rate-limiting mechanisms are also discussed. 4 refs., 18 figs., 4 tabs.

  19. Calcium isolation from large-volume human urine samples for 41Ca analysis by accelerator mass spectrometry.

    PubMed

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

    2013-08-01

    Calcium oxalate precipitation is the first step in preparation of biological samples for (41)Ca 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 (41)Ca administration during which human samples, collected over a lifetime, provide (41)Ca:Ca ratios that are significantly above background.

  20. Cosmogenic 26Al/10Be surface production ratio in Greenland

    NASA Astrophysics Data System (ADS)

    Corbett, Lee B.; Bierman, Paul R.; Rood, Dylan H.; Caffee, Marc W.; Lifton, Nathaniel A.; Woodruff, Thomas E.

    2017-02-01

    The assumed value for the cosmogenic 26Al/10Be surface production rate ratio in quartz is an important parameter for studies investigating the burial or subaerial erosion of long-lived surfaces and sediments. Recent models and data suggest that the production ratio is spatially variable and may be greater than originally thought. Here we present measured 26Al/10Be ratios for 24 continuously exposed bedrock and boulder surfaces spanning 61-77°N in Greenland. Empirical measurements, such as ours, include nuclides produced predominately by neutron-induced spallation with percent-level contributions by muon interactions. The slope of a York regression line fit to our data is 7.3 ± 0.3 (1σ), suggesting that the 26Al/10Be surface production ratio exceeds the commonly used value of 6.75, at least in the Arctic. A higher 26Al/10Be production ratio has implications for multinuclide cosmogenic isotope studies because it results in greater modeled burial durations and erosion rates.

  1. An Alluvial Surface Chronology Based on Cosmogenic 36Cl Dating, Ajo Mountains (Organ Pipe Cactus National Monument), Southern Arizona

    NASA Astrophysics Data System (ADS)

    Liu, Beiling; Phillips, Fred M.; Pohl, Molly M.; Sharma, Pankaj

    1996-01-01

    A chronology of alluvial surfaces on piedmont slopes below the western Ajo Mountains, southern Arizona, has been obtained using cosmogenic 36Cl accumulation and AMS radiocarbon dating. The apparent 36Cl ages of individual boulders range from 520,000 to 13,000 yr, and the 14C ages of organic material in the two young terraces are 2750-2350 and 17,800 cal yr B.P. The sequence of 36Cl ages is consistent with the apparent stratigraphic order, but groupings of similar ages for different surfaces appear to result from repeated reworking of older surfaces associated with the deposition of younger ones. The youngest surface gave a distribution of 36Cl ages about 30,000 yr older than the 14C and soil ages; however, this distribution had 36Cl ages that overlapped with 36Cl ages from active channels and hillslopes. We attribute the older-than-expected exposure ages of sampled boulders to inheritance of 36Cl while residing near the surface during very slow erosion on the mountain front. Our results show that although cosmogenic nuclide accumulation can help establish chronologies for surfaces in piedmont settings, care must be used in evaluating the effects of complex exposure histories.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 26Al and 10Be Activities of Lodranites and Winona

    NASA Astrophysics Data System (ADS)

    Herzog, G. F.; Xue, S.; Klein, J.; Juenemann, D.; Middleton, R.

    1993-07-01

    Noble gas measurements by [1] indicate that four lodranites LEW 88280, Lodran (a fall), MAC 88177, and Yamato 791491 have the same cosmic ray exposure age of a few million years. The elevated ^22Ne/^21Ne ratios of these lodranites, from 1.22 to 1.28 [1], suggest that shielding was light and production rates appreciably lower than in average chondrites. Cosmic-ray irradiation in space for, say, 4 My would bring ^26Al and ^10Be to within 2% and 16% of their respective saturation values. Thus measurement of ^26Al may provide information about production rates and shielding and ^10Be about exposure age. We separated magnetically metal- and silicate-rich material from the four lodranites mentioned above and from Winona. The ^26Al and/or ^10Be activities (Table 1) were measured by accelerator mass spectrometry [2] with the statistical 1-sigma precision shown; the activities are thought to have an overall accuracy of 6-8%. Although the metal phases were etched with HF, they retained some silicate. To get a quantitative indication of the amounts of silicate present, the Mg concentrations in aliquots of the dissolved metal samples (Table 1) were measured by ICP/MS. The Mg, Al, Ca, Ti, Mn, and Fe contents of the silicate phases were determined by DCP emission spectrometry [3]. The measured activities in silicates from LEW 88280, Lodran, and Y 791491 resemble one another closely: The average ^26Al and ^10Be activities are 50.9 and 16.7 dpm/kg compared to estimated production rates of about 55 and 23 dpm/kg. These results lead to an exposure age of ~3.3 My, but do not indicate substantial lowering of production rates. The ^26Al and ^10Be contents of MAC 88177 are about half the values expected at saturation under normal shielding and are lower than those in the other three lodranites. These results are consistent with the very light shielding inferred from the exceptionally high ^22Ne/^21Ne ratio of 1.28, and perhaps with some lowering due to terrestrial age. Kirsten et al. [4

  8. 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.

  9. Estimation of thermal neutron fluences in the concrete of proton accelerator facilities from 36Cl production

    NASA Astrophysics Data System (ADS)

    Bessho, K.; Matsumura, H.; Miura, T.; Wang, Q.; Masumoto, K.; Hagura, H.; Nagashima, Y.; Seki, R.; Takahashi, T.; Sasa, K.; Sueki, K.; Matsuhiro, T.; Tosaki, Y.

    2007-06-01

    The thermal neutron fluence that poured into the shielding concrete of proton accelerator facilities was estimated from the in situ production of 36Cl. The thermal neutron fluences at concrete surfaces during 10-30 years of operation were in the range of 1012-1014 n/cm2. The maxima in thermal neutron fluences were observed at ≈5-15 cm in the depths analyzed for 36Cl/35Cl by AMS. These characteristics imply that thermalization of neutrons occurred inside the concrete. Compared to the several tens of MeV cyclotrons, secondary neutrons penetrate deeper into the concrete at the high-energy accelerators possessing acceleration energies of 400 MeV and 12 GeV. The attenuation length of neutrons reflects the energy spectra of secondary neutrons emitted by the nuclear reaction at the beam-loss points. Increasing the energy of secondary neutrons shifts the maximum in the thermal neutron fluences to deeper positions. The data obtained in this study will be useful for the radioactive waste management at accelerator facilities.

  10. The in vitro reduction of sodium [36Cl]chlorate in bovine ruminal fluid.

    PubMed

    Oliver, C E; Bauer, M L; Caton, J S; Anderson, R C; Smith, D J

    2007-08-01

    Sodium chlorate effectively reduces or eliminates gram-negative pathogenic bacteria in the gastrointestinal tracts of live cattle. Limitations to the in vivo efficacy of chlorate are its rapid absorption from the gastrointestinal tract and its presumed reduction to chloride within the gastrointestinal tract. We hypothesized that chlorate would be reduced via ruminal bacteria in a ruminal in vitro system and that the reduction of chlorate would be influenced by the dietary for-age:concentrate ratio; thus, 4 ruminally cannulated steers were fed 20 or 80% concentrate diets in a crossover design. Ruminal fluid was collected in 2 periods and dispensed into in vitro tubes containing sodium [36Cl]chlorate, which was sufficient for 100 or 300 mg/L final chlorate concentrations. The tubes were incubated for 0, 1, 4, 8, 16, or 24 h; autoclaved, control ruminal fluid, fortified with sodium [36Cl]chlorate, was incubated for 24 h. Chlorate remaining in each sample was measured by liquid scintillation counting after [36Cl]chloride was precipitated with silver nitrate. A preliminary study indicated that chlorite, a possible intermediate in the reduction of chlorate, had a half-life of approximately 4.5 min in freshly collected (live) ruminal fluid; chlorite was, therefore, not specifically measured in ruminal incubations. The chlorate dose did not affect in vitro DM digestion (P > or = 0.11), whereas in vitro DM digestibility was decreased (P < or = 0.05) by 80% forage content. By 24 h, 57.5 +/- 2.6% of the chlorate remained in 100-mg/L incubations, whereas 78.2 +/- 2.6% of the chlorate remained in the 300-mg/L incubations. When the data were expressed on a concentration basis (mg/L), diet had no effect (P > or = 0.18) on chlorate reduction; however, when chlorate reduction was expressed on a percentage basis, chlorate reduction tended to be greater (P > or = 0.09) at 8 and 16 h in the incubations containing the low-concentrate diet. Chlorate remaining in autoclaved controls at

  11. Measurement of low levels of 26Al from meteorite samples.

    PubMed

    Johnston, Peter N; Hult, Mikael; Altzitzoglo, Timotheos

    2002-01-01

    As part of an intercomparison to resolve discrepancies between accelerator mass spectrometry results and radiometric results, the 26Al activity in four meteorite samples was measured using ultra low-level gamma-ray spectrometry in the underground laboratory HADES. Although reference sources were used, extensive use was made of computer modelling to determine corrections for absorption, coincidence summing between gamma rays in the decays and annihilation radiation following positron emission. Directional correlation corrections were also taken into account. The limiting uncertainties in these measurements arose from counting statistics of 5-9%. Some computer modelling was undertaken to determine optimum geometry for this type of intercomparison involving gamma-ray spectrometry.

  12. (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.

  13. A new Holocene eruptive history of Erebus volcano, Antarctica using cosmogenic 3He and 36Cl

    NASA Astrophysics Data System (ADS)

    Parmelee, D. E.; Kyle, P. R.; Kurz, M. D.; Marrero, S.

    2013-12-01

    Unraveling the timing of a volcano's most recent eruptions is crucial to understanding its present and future behavior. In this study, we use cosmogenic 3He and 36Cl in mineral separates (clinopyroxene and anorthoclase, respectively) to date the 10 most recent lava flows on Erebus volcano. Erebus is a 2,170-km3 active stratovolcano on Ross Island, Antarctica that is known for its persistent anorthoclase phonolite lava lake and frequent Strombolian eruptions. Previous anorthoclase 40Ar/39Ar ages from the 10 flows [1, 2] suggest they were erupted at roughly regular intervals between 17 and 0 ka. However, the uncertainties on the Ar ages are large (up to 39 %), and the likelihood of excess 40Ar in melt inclusions may skew the Ar ages older than eruption ages. The new cosmogenic ages provide new insights into Erebus eruption chronology. We used two different models to scale production rates: the Lal/Stone model [3] and the new Sato/Lifton model [4]. We find ~20-25 % younger ages with the Sato/Lifton model, attributable to different treatment of atmospheric pressure effects, solar modulation effects, and muogenic production rates in each model. 3He and 36Cl exposure ages of the same 10 flows range from 4.5 × 0.1 to 9.7 × 0.2 ka (Lal/Stone) or 3.5 × 0.1 to 7.5 × 0.2 ka (Sato/Lifton), significantly different than the Ar ages, with a much shorter eruption period. Surprisingly, three of the flows have exposure ages older than their Ar ages, despite the exposure ages being considered minimum ages of eruption and the Ar ages maxima. Concordance of the 3He and 36Cl ages measured in the same samples strengthens the validity of our results and implies that the 3He and 36Cl production rates [5] are well-calibrated for high latitude, high altitude sites and that the methodologies are robust. Regardless of which scaling model is used, the results yield a new understanding of the current eruptive phase of Erebus, particularly in documenting the short timespan over which the

  14. 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.

  15. In-Situ Cosmogenic 36Cl Production Rate Calibration from Basaltic Flows of Mount Etna (Sicily, 38° N)

    NASA Astrophysics Data System (ADS)

    Schimmelpfennig, I.; Benedetti, L.; Pik, R.; Burnard, P.; Blard, P. H.; Bourles, D.

    2007-12-01

    One of the CRONUS-EU goals is to provide high quality calibration sites from independently dated surfaces. Several previous studies have been conducted on 36Cl production rate calibration (e.g. Stone et al. 1996, Phillips et al. 2001), which, however, used different protocols and yielded 36Cl production rates with up to 40% discrepancies. The objectives of this study are 1- to understand the source of these discrepancies and 2- to calibrate 36Cl production rates from its target elements Ca and K. As a first step we focused on testing the chemical protocol by performing a sequential 36Cl extraction experiment on whole rock grains and Ca-rich plagioclase from the same sample. The sample was collected at Mt. Etna on a pahoehoe flow, which has a K-Ar fossil exposure time of (10±3) kyr. Cosmogenic 3He was also precisely measured within cogenetic olivine phenocrysts of this sample (Blard et al. 2005) and yields an exposure time of (10.4±1.5) kyr. Both, total Cl and 36Cl concentrations from the first dissolution steps are high, 5800 ppm (whole rock) and 450 ppm (plagioclase) Cl, and 107 - 106 atoms 36Cl/g of rock dissolved. After about 20% dissolution of the plagioclase sample, Cl is almost completely removed (1-3ppm) and 36Cl concentrations reach a plateau value of 2*105 atoms/g of rock. Using the Stone et al. (1996) and Evans et al. (1997) 36Cl production rates for the target elements Ca and K, respectively, this plateau concentration yields an exposure age which is in excellent agreement with K-Ar dating and cosmogenic 3He ages. On the contrary, in the whole rock sample total Cl concentrations remain high (>330ppm) resulting in a considerable 36Cl production from capture of low-energy neutrons by 35Cl, an additional and still not well-constrained 36Cl production mechanism. The resulting exposure ages from the whole rock are 35-45% higher than the independent 3He ages. For 36Cl production rate calibration from Ca, we will use separated Ca-rich plagioclase from various

  16. 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.

  17. Groundwater and surface water flow to the Merced River, Yosemite Valley, California: 36Cl and Cl- evidence

    NASA Astrophysics Data System (ADS)

    Shaw, Glenn D.; Conklin, Martha H.; Nimz, Gregory J.; Liu, Fengjing

    2014-03-01

    Our current understanding of water fluxes and flow paths within the mountain block is limited, and improved understanding is necessary to assess hydrology more accurately above the mountain front. Source waters and the processes controlling their mixing were characterized in the Merced River basin within Yosemite National Park, California, using 36Cl and Cl-, supported by 222Rn, δ18O, δD, and streamflow data. Streams, snow, groundwater, and springs were sampled seasonally from July 2004 to October 2007. Three source water end-members were identified: (i) near surface runoff of recent meltwater containing bomb-pulse 36Cl (36ClBP), (ii) shallow, evapotranspired groundwater, and (iii) groundwater containing Cl- derived through extended rock interaction. Both groundwater end-members mix in Yosemite Valley and then later discharge to the Merced River. Near surface runoff dominates all stream hydrographs during snowmelt, whereas the two groundwater end-members become significantly more important during base flow. Tributaries consist of mixtures of the shallow evapotranspired groundwater and near surface runoff, whereas the Merced River is composed of the mixture of all source water end-members. Snow is not an obvious end-member, and elevated 36ClBP in the near surface runoff suggests that 36ClBP was retained efficiently, and is being slowly released as meltwater interacts with the soil. The use of 36Cl as a natural tracer is important in revealing the processes controlling streamflow generation in large montane catchments and the results will be helpful in configuring and calibrating hydrologic models.

  18. 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.

  19. Pharmacokinetics of ruminally dosed sodium [36Cl]chlorate in beef cattle.

    PubMed

    Oliver, C E; Craigmill, A L; Caton, J S; Anderson, R C; Smith, D J

    2007-08-01

    The recently recognized potential of sodium chlorate as a possible preharvest food safety tool for pathogen reduction in meat animals has spurred interest in the pharmacokinetics of intraruminally dosed chlorate. Six Loala cattle were assigned (one heifer and one steer per treatment) to one of three intraruminal doses of radiolabeled sodium [36Cl]chlorate (21, 42, or 63 mg/kg body weight) administered in four equal aliquots over a 24-h period. Blood and serum were collected (29 samples in 48 h). Total radioactive residues were measured and the radioactive moieties were speciated. Chlorate appeared rapidly in blood and serum after dosing. For animals administered a dose of 42 or 63 mg/kg, the half-life of absorption was estimated at 0.6-0.9 h. Serum chlorate concentrations progressively increased with aliquot administration until peaking at 6-21 parts per million at 26 h. Between aliquot administrations, serum chlorate levels typically peaked in 3.5 h or less. The half-life of chlorate elimination ranged between 6.9 and 11 h, depending on the dose. Ultimately, absorption of chlorate removes it from its desired site of action, the lower gastrointestinal tract, thereby reducing its efficacy. Further research is needed to develop a chlorate formulation that will allow passage to the lower gastrointestinal tract.

  20. Tissue distribution, elimination, and metabolism of dietary sodium [36Cl]chlorate in beef cattle.

    PubMed

    Smith, David J; Anderson, Robin C; Ellig, Dee A; Larsen, Gerald L

    2005-05-18

    Two steers (approximately 195 kg) were each dosed with 62.5 or 130.6 mg/kg body weight sodium [36Cl]chlorate for three consecutive days. All excreta were collected during the dosing and 8 h withdrawal periods. The apparent radiochlorine absorption was 62-68% of the total dose with the major excretory route being urine. Parent chlorate was 65-100% of the urinary radiochlorine; chloride was the only other radiochlorine species present. Similarly, residues in edible tissues were composed of chloride and chlorate with chloride being the major radiolabeled species present. Chlorate represented 28-57% of the total radioactive residues in skeletal muscle; in liver, kidney, and adipose tissues, chlorate ion represented a smaller percentage of the total residues. Chlorate residues in the low dose steer were 26 ppm in kidney, 14 ppm in skeletal muscle, 2.0 ppm in adipose tissue, and 0.7 ppm in liver. These data indicate that sodium chlorate may be a viable preharvest food safety tool for use by the cattle industry.

  1. 26Al incorporation into the tissues of suckling rats through maternal milk

    NASA Astrophysics Data System (ADS)

    Yumoto, S.; Nagai, H.; Kobayashi, K.; Tada, W.; Horikawa, T.; Matsuzaki, H.

    2004-08-01

    Aluminium (Al) is highly neurotoxic and inhibits prenatal and postnatal development of the brain in humans and experimental animals. However, Al incorporation into the brain of sucklings through maternal milk has not yet been well clarified because Al lacks a suitable isotope for radioactive tracer experiments. Using 26Al as a tracer, we measured 26Al incorporation into the brain of suckling rats by accelerator mass spectrometry. Lactating rats were subcutaneously injected with 26AlCl3 from day 1 to day 20 postpartum. Suckling rats were weaned from day 21 postpartum. From day 5 to day 20 postpartum, the 26Al levels measured in the brain, liver, kidneys and bone of suckling rats increased significantly. After weaning, the amounts of 26Al in the liver and kidneys decreased remarkably. However, the 26Al amount in the brain had diminished only slightly up to 140 days after weaning.

  2. 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.

  3. (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).

  4. Did 26Al and impact-induced heating differentiate Mercury?

    NASA Astrophysics Data System (ADS)

    Bhatia, G. K.; Sahijpal, S.

    2017-02-01

    Numerical models dealing with the planetary scale differentiation of Mercury are presented with the short-lived nuclide, 26Al, as the major heat source along with the impact-induced heating during the accretion of planets. These two heat sources are considered to have caused differentiation of Mars, a planet with size comparable to Mercury. The chronological records and the thermal modeling of Mars indicate an early differentiation during the initial 1 million years (Ma) of the formation of the solar system. We theorize that in case Mercury also accreted over an identical time scale, the two heat sources could have differentiated the planets. Although unlike Mars there is no chronological record of Mercury's differentiation, the proposed mechanism is worth investigation. We demonstrate distinct viable scenarios for a wide range of planetary compositions that could have produced the internal structure of Mercury as deduced by the MESSENGER mission, with a metallic iron (Fe-Ni-FeS) core of radius 2000 km and a silicate mantle thickness of 400 km. The initial compositions were derived from the enstatite and CB (Bencubbin) chondrites that were formed in the reducing environments of the early solar system. We have also considered distinct planetary accretion scenarios to understand their influence on thermal processing. The majority of our models would require impact-induced mantle stripping of Mercury by hit and run mechanism with a protoplanet subsequent to its differentiation in order to produce the right size of mantle. However, this can be avoided if we increase the Fe-Ni-FeS contents to 71% by weight. Finally, the models presented here can be used to understand the differentiation of Mercury-like exoplanets and the planetary embryos of Venus and Earth.

  5. 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

  6. 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.

  7. 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

  8. 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.

  9. {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.

  10. 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.

  11. 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.

  12. 26Al incorporation into the brain of rat fetuses through the placental barrier and subsequent metabolism in postnatal development

    NASA Astrophysics Data System (ADS)

    Yumoto, Sakae; Nagai, Hisao; Kakimi, Shigeo; Matsuzaki, Hiroyuki

    2010-04-01

    Aluminium (Al) inhibits prenatal and postnatal development of the brain. We used 26Al as a tracer, and measured 26Al incorporation into rat fetuses through the placental barrier by accelerator mass spectrometry (AMS). From day 15 to day 18 of gestation, 26AlCl 3 was subcutaneously injected into pregnant rats. Considerable amounts of 26Al were measured in the tissues of newborn rats immediately after birth. The amounts of 26Al in the liver and kidneys decreased rapidly during postnatal development. However, approximately 15% of 26Al incorporated into the brain of fetuses remained in the brain of adult rats 730 days after birth.

  13. 26Al-26Mg systematics in chondrules from Kaba and Yamato 980145 CV3 carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

    Nagashima, Kazuhide; Krot, Alexander N.; Komatsu, Mutsumi

    2017-03-01

    We report the mineralogy, petrography, and in situ measured 26Al-26Mg systematics in chondrules from the least metamorphosed CV3 (Vigarano-type) chondrites, Kaba and Yamato (Y) 980145. Two Y 980145 chondrules measured show no resolvable excesses in 26Mg (26Mg∗), a decay product of a short-lived (t1/2 ∼0.7 Ma) radionuclide 26Al. Plagioclase in one of the chondrules is replaced by nepheline, indicative of thermal metamorphism. The lack of 26Mg∗ in the Y 980145 chondrules is most likely due to disturbance of their 26Al-26Mg systematics during the metamorphism. Although Kaba experienced extensive metasomatic alteration (<300 °C), it largely avoided subsequent thermal metamorphism, and the 26Al-26Mg systematics of its chondrules appear to be undisturbed. All eight Kaba chondrules measured show 26Mg∗, corresponding to the initial 26Al/27Al ratios [(26Al/27Al)0] ranging from (2.9 ± 1.7) × 10-6 to (6.3 ± 2.7) × 10-6. If CV parent asteroid accreted rapidly after chondrule formation, the inferred (26Al/27Al)0 ratios in Kaba chondrules provide an upper limit on 26Al available in this asteroid at the time of its accretion. The estimated initial abundance of 26Al in the CV asteroid is too low to melt it and contradicts the existence of a molten core in this body suggested from the paleomagnetic records of Allende [Carporzen et al. (2011) Magnetic evidence for a partially differentiated carbonaceous chondrite parent body. Proc. Natl. Acad. Sci. USA108, 6386-6389] and Kaba [Gattacceca et al. (2013) More evidence for a partially differentiated CV parent body from the meteorite Kaba. Lunar Planet. Sci.44, abstract#1721].

  14. "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

  15. Effect of sodium [36Cl]chlorate dose on total radioactive residues and residues of parent chlorate in growing swine.

    PubMed

    Smith, D J; Anderson, R C; Huwe, J K

    2006-11-01

    An experimental chlorate-based product has been shown to be efficacious in eliminating economically important, Gram-negative human pathogens in the gastrointestinal tracts of food animals. Prior to the commercial marketing of such a product, the magnitude and chemical nature of residues remaining in edible tissues must be determined. Thus, the objective of this study was to determine the tissue distribution and elimination of sodium [36Cl]chlorate in orally dosed swine. Three sets of pigs, each consisting of a barrow and a gilt, were orally dosed with a total of 20, 40, or 60 mg of sodium [36Cl]chlorate per kg body weight via the drinking water. Urine and feces were collected throughout the 30 h study. Twenty-four hours after the last exposure to [36Cl]chlorate, each pig was harvested and both edible and inedible tissues were collected. Urine and tissue samples were analyzed for total radioactive residues and for chlorate metabolites. Elimination of radioactivity in urine averaged 81.6, 83.7, and 83.9% of the total dose for the low, medium, and high doses, respectively. Fecal elimination of radioactivity averaged 1.1% of the dosed radiochlorine across all doses. Parent chlorate always represented greater than 97.4% of the urinary radiochlorine with the remaining radiochlorine being excreted as chloride ion. Chlorate represented 39-77% of fecal radioactivity, depending upon dose. Chlorate concentrations in edible tissues ranged from 0.01 to 0.49 ppm, with residues in liver and skeletal muscle generally lower than those in kidney and adipose tissue. Chlorate residues were concentrated in thyroid tissues (7.7-25.4 ppm) relative to edible tissues. No evidence for the presence of chlorite was observed in excreta or in tissues. Results of this study suggest that further development of chlorate as a preharvest food safety tool in swine merits consideration.

  16. Reconstructing the paleoseismic history of the Priene-Sazli Fault using 36Cl cosmogenic nuclide dating method, Western Anatolia, Turkey

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    The 300-km wide West Anatolian Extensional Province is one of the regions of intense seismic activity in the world within the Alpine-Himalayan belt. Deformation pattern in the area is controlled by three major E-W trending graben systems of Gediz, Küçük Menderes and Büyük Menderes which have been formed as a result of roughly N-S extensional tectonic regime since the early Miocene. These graben systems show evidences of surface faulting during the Pleistocene-Holocene and are geomorphologically characterized by well-exposed limestone normal fault scarps with a relief of tens of meters and well-preserved slickenlines. Since limestones are resistant to weathering, the limestone scarps can efficiently record several past earthquakes. Cosmogenic 36Cl is the only element to identify and date the rupture events. Each rupture causes exposure of previously buried section of the scarp to the surface. Accordingly, due to being well enough exposed to cosmic rays, accumulation of 36Cl accelerates during period of quiescence. Thus, distribution of measured 36Cl concentrations can be applied to investigate periods of seismic activity and inactivity and also to calculate the vertical displacement along the fault plane in association with each rupture. In this study, we focus on the Priene-Sazli Fault, located on the most western part of Büyük Menderes graben. Along the active fault zone, well exposed archaeological sites (e.g. Priene) have been discovered, where destructive historical earthquakes have left evidence of ancient damages in the historical period and during the 20th century. The Priene-Sazli Fault caused the July 16, 1955 Söke-Balat earthquake (M=6.8) with fault-plane solution indicating of normal southeast downthrow along with subsidiary dextral motion. We collected 117 samples from four continuous strips on the Priene-Sazli Fault to measure 36Cl concentrations. We used a new Matlab code to identify the significant ruptures and their timing. Our preliminary

  17. 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

  18. 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

  19. 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

  20. Understanding groundwater fracture-flow and near surface soil throughflow mixing within a mountain catchment using 36Cl/Cl, Yosemite National Park, California.

    NASA Astrophysics Data System (ADS)

    Shaw, G. D.; Conklin, M. H.; Nimz, G. J.

    2008-12-01

    In high elevation montane basins, there are typically limited observations to characterize watersheds. In this study we successfully use 36Cl and Cl- to characterize groundwater and near-surface water contributions to the upper Merced River and it's tributaries from Happy Isles to El Portal. Water fluxes typically consist of a variety of surface, near-surface and groundwater flow paths, which are complicated by faulted, folded, and fractured terrain. Surface water, snow, groundwater, and springs were sampled seasonally from July 2004 to October 2007. Snow 36Cl/Cl ratios are 3-30 times lower than in the Merced River water, but 36Cl/Cl ratios in the river increase 3-7 times from baseflow to the snowmelt season. This observation can be explained by characterizing endmembers in the watershed, and by determining how these endmembers vary temporally. Three endmembers mix in the catchment, and they include near-surface water with Cl- concentrations of 0.09 mg/L and 36Cl/Cl of 9976x10-15, groundwater primarily in contact with granitic rock with Cl- of 0.39 mg/L and 36Cl/Cl of 10711x10-15, and groundwater primarily in contact with metasedimentary rock with Cl- of 32.7 mg/L and 36Cl/Cl of 71x10-15. Metamorphic- dominated groundwater and granitic-dominated groundwater are further characterized by Ca2+/Cl- ratios (granitic-dominated groundwater is greater than 5, and metamorphic-dominated groundwater is less than 1). As the season transitions from snowmelt to baseflow, Cl- and 36Cl/Cl in surface water becomes more characteristic of both granitic and metamorphic-dominated groundwater depending on location. Plotting 1/Cl- verses 36Cl/Cl elucidates mixing lines which indicate that both groundwater endmembers have undergone evapotranspiration, but only the metamorphic-dominated groundwater shows evidence of incorporating significant amounts of rock chloride. The near-surface water is the dominant endmember during the snowmelt season and has similar Cl- concentrations as snow (~0

  1. Harvesting the Decay Energy of 26-Al to Drive Lightning Discharge and Chondrule Formation

    NASA Astrophysics Data System (ADS)

    Johansen, A.; Okuzumi, S.

    2017-02-01

    We demonstrate that positrons released in the decay of 26-Al cause large-scale charging of dense pebble regions. The charge separation is neutralized by lightning discharge and this can lead to the formation of chondrules.

  2. Cross-sections for 36Cl from Ti at E p=35-150 MeV: Applications to in-situ exposure dating

    NASA Astrophysics Data System (ADS)

    Fink, David; Vogt, Stephan; Hotchkis, Michael

    2000-10-01

    We have measured the low-energy yield of 36Cl from Ti for proton energies from 35 to 150 MeV. Thin Ti foil irradiations were performed at the Harvard University Cyclotron Laboratory and 36Cl concentrations were determined using the ANTARES AMS facility at ANSTO. Cross-sections ranged smoothly with energy from 0.32±0.05 mb at 35 MeV to 5.3±0.4 mb at 150 MeV. Results for E<110 MeV are new, while the upper region from 110 to 150 MeV agrees well with overlapping data from other studies. The in-situ production rate for 36Cl from Ti at the earth's surface and high latitude based on this excitation function and calculations of Masarik and Reedy (normalised to the mean measured yield of 36Cl from Ca) is estimated at ˜(13±3) atoms 36Cl (g Ti yr) -1. We thus conclude that in Ti-rich, Ca-poor rocks or in typical basalts, 36Cl yield from Ti can amount to ˜5-10% of total. This is similar to the contribution from slow muon capture on 40Ca and in some cases, from thermal neutron capture on native Cl.

  3. 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.

  4. (41)Ca in Tooth Enamel. Part II: A means for retrospective biological neutron dosimetry in atomic bomb survivors.

    PubMed

    Rühm, W; Wallner, A; Cullings, H; Egbert, S D; El-Faramawy, N; Faestermann, T; Kaul, D; Knie, K; Korschinek, G; Nakamura, N; Roberts, J; Rugel, G

    2010-08-01

    (41)Ca is produced mainly by absorption of low-energy neutrons on stable (40)Ca. We used accelerator mass spectrometry (AMS) to measure (41)Ca in enamel of 16 teeth from 13 atomic bomb survivors who were exposed to the bomb within 1.2 km from the hypocenter in Hiroshima. In our accompanying paper (Wallner et al., Radiat. Res. 174, 000-000, 2010), we reported that the background-corrected (41)Ca/Ca ratio decreased from 19.5 x 10(-15) to 2.8 x 10(-15) with increasing distance from the hypocenter. Here we show that the measured ratios are in good correlation with gamma-ray doses assessed by electron paramagnetic resonance (EPR) in the same enamel samples, and agree well with calculated ratios based on either the current Dosimetry System 2002 (DS02) or more customized dose estimates where the regression slope as obtained from an errors-in-variables linear model was about 0.85. The calculated DS02 neutron dose to the survivors was about 10 to 80 mGy. The low-energy neutrons responsible for (41)Ca activation contributed variably to the total neutron dose depending on the shielding conditions. Namely, the contribution was smaller (10%) when shielding conditions were lighter (e.g., outside far away from a single house) and was larger (26%) when they were heavier (e.g., in or close to several houses) because of local moderation of neutrons by shielding materials. We conclude that AMS is useful for verifying calculated neutron doses under mixed exposure conditions with gamma rays.

  5. Evidence for Widespread 26Al in the Solar Nebula and Constraints for Nebula Time Scales

    PubMed

    Russell; Srinivasan; Huss; Wasserburg; MacPherson

    1996-08-09

    A search was made for 26Mg (26Mg*) from the decay of 26Al (half-life = 0.73 million years) in Al-rich objects from unequilibrated ordinary chondrites. Two Ca-Al-rich inclusions (CAIs) and two Al-rich chondrules (not CAIs) were found that contained 26Al when they formed. Internal isochrons for the CAIs yielded an initial 26Al/27Al ratio [(26Al/27Al)0] of 5 x 10(-5), indistinguishable from most CAIs in carbonaceous chondrites. This result shows that CAIs with this level of 26Al are present throughout the classes of chondrites and strengthens the notion that 26Al was widespread in the early solar system. The two Al-rich chondrules have lower 26Mg*, corresponding to a (26Al/27Al)0 ratio of approximately 9 x 10(-6). Five other Al-rich chondrules contain no resolvable 26Mg*. If chondrules and CAIs formed from an isotopically homogeneous reservoir, then the chondrules with 26Al must have formed or been last altered approximately2 million years after CAIs formed; the 26Mg*-free chondrules formed >1 to 3 million years later still. Because 26Mg*-containing and 26Mg*-free chondrules are both found in Chainpur, which was not heated to more than approximately400°C, it follows that parent body metamorphism cannot explain the absence of 26Mg* in some of these chondrules. Rather, its absence indicates that the lifetime of the solar nebula over which CAIs and chondrules formed extended over approximately5 million years.

  6. {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.

  7. 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.

  8. 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.

  9. Early accretion of protoplanets inferred from a reduced inner solar system (26)Al inventory.

    PubMed

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

    2015-06-15

    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 (26)Al ((26)Al→(26)Mg; 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 (26)Al abundance [((26)Al/(27)Al)0] exists only for the oldest known solids, calcium aluminum-rich inclusions (CAIs) - the so-called canonical value. We have determined the (26)Al/(27)Al 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 ((26)Al/(27)Al)0 of [Formula: see text] 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 (54)Cr/(52)Cr ratios, most inner solar system materials likely accreted from material containing a similar (26)Al/(27)Al ratio as the APB precursor at the time of CAI formation. To satisfy the abundant evidence for widespread planetesimal differentiation, the subcanonical (26)Al budget requires that differentiated planetesimals, and hence protoplanets, accreted rapidly within 0.25 ± 0.15 Ma of the formation of canonical CAIs.

  10. 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.

  11. 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.

  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. 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

  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. Phase Polymorphism, Molecular Motions and Structural Changes in [Cr(NH3)6](ClO4)3

    NASA Astrophysics Data System (ADS)

    Mikuli, Edward; Górska, Natalia; Wróbel, Stanisław; Ściesińskic, Jacek; Ściesińska, Ewa

    2007-04-01

    A phase transition in [Cr(NH3)6](ClO4)3 at Thc = 293.5 K (on heating) and Tcc = 293.0 K (on cooling) was determined by differential scanning calorimetry. The temperature dependences of the full width at half maximum of the bands connected with ρr(NH3)F1u and δd(ClO)E modes suggest that the discovered phase transition is not connected with drastic changes in the speed of reorientational motions of the NH3 ligands nor the ClO4 - anions. Temperature dependence of the FT-FIR spectra and the diffraction patterns show that the discovered phase transition is caused by a change in the crystal structure.

  16. {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.

  17. 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.

  18. Can cosmogenic nuclides (36Cl) unravel the timing of dislocation of tsunami blocks on Bonaire (Leeward Antilles)?

    NASA Astrophysics Data System (ADS)

    Engel, Max; Rixhon, Gilles; Brückner, Helmut; May, S. Matthias; Binnie, Steve; Dunai, Tibor J.

    2013-04-01

    On Bonaire (Leeward Antilles) and rocky coasts worldwide, high-energy wave events (tsunamis, storms) dislocate coarse-clast deposits (Engel and May, 2012). Using these onshore blocks and boulders to derive ages for the most powerful events on millennial scales is still a major challenge. We apply terrestrial cosmogenic nuclides (TCN), in particular 36Cl, in case of the largest blocks in order to directly date the transport event(s), i.e. the inferred tsunami(s). This dating method has hitherto been disregarded in the coastal environment, particularly in the context of block transport. The following characteristics of the blocks are fundamental for the success of the presented dating approach: (1) due to the lithology (aragonite, calcite), concentration measurements of 36Cl are performed; (2) only large and thick boulders and blocks (>50 t, >2 m thickness) for which tsunami transport was inferred (Engel and May, 2012) were sampled; (3) since the boulders stem from the edge of the coral reef platform, they had been exposed to cosmic radiation prior to the transport event(s) and had already accumulated a certain amount of TCN. To avoid this problem of inheritance, we only sampled the thickest clasts, and those having experienced a 180° overturn during transport; thus, having exposed a "blank" side to cosmic rays only since the event. The complete overturn is attested by the presence of inactive rock pools in upside-down position and bioerosive notches. Engel, M., and May, S. M.: Bonaire's boulder fields revisited: Evidence for Holocene tsunami impact on the Leeward Antilles, Quat. Sci. Rev., 54, 126-141, 2012.

  19. Effect of sodium [36Cl]chlorate dose on total radioactive residues and residues of parent chlorate in beef cattle.

    PubMed

    Smith, D J; Oliver, C E; Caton, J S; Anderson, R C

    2005-09-07

    The objectives of this study were to determine total radioactive residues and chlorate residues in edible tissues of cattle administered at three levels of sodium [36Cl]chlorate over a 24-h period and slaughtered after a 24-h withdrawal period. Three sets of cattle, each consisting of a heifer and a steer, were intraruminally dosed with a total of 21, 42, or 63 mg of sodium [36Cl]chlorate/kg of body weight. To simulate a 24-h exposure, equal aliquots of the respective doses were administered to each animal at 0, 8, 16, and 24 h. Urine and feces were collected in 12-h increments for the duration of the 48-h study. At 24 h after the last chlorate exposure, cattle were slaughtered and edible tissues were collected. Urine and tissue samples were analyzed for total radioactive residues and for metabolites. Elimination of radioactivity in urine and feces equaled 20, 33, and 48% of the total dose for the low, medium, and high doses, respectively. Chlorate and chloride were the only radioactive chlorine species present in urine; the fraction of chlorate present as a percentage of the total urine radioactivity decreased with time regardless of the dose. Chloride was the major radioactive residue present in edible tissues, comprising over 98% of the tissue radioactivity for all animals. Chlorate concentrations in edible tissues ranged from nondetectable to an average of 0.41 ppm in skeletal muscle of the high-dosed animals. No evidence for the presence of chlorite was observed in any tissue. Results of this study suggest that further development of chlorate as a preharvest food safety tool merits consideration.

  20. Distribution of 26Al in the CR chondrite chondrule-forming region of the protoplanetary disk

    NASA Astrophysics Data System (ADS)

    Schrader, Devin L.; Nagashima, Kazuhide; Krot, Alexander N.; Ogliore, Ryan C.; Yin, Qing-Zhu; Amelin, Yuri; Stirling, Claudine H.; Kaltenbach, Angela

    2017-03-01

    We report on the mineralogy, petrography, and in situ measured oxygen- and magnesium-isotope compositions of eight porphyritic chondrules (seven FeO-poor and one FeO-rich) from the Renazzo-like carbonaceous (CR) chondrites Graves Nunataks 95229, Grosvenor Mountains 03116, Pecora Escarpment 91082, and Queen Alexandra Range 99177, which experienced minor aqueous alteration and very mild thermal metamorphism. We find no evidence that these processes modified the oxygen- or Al-Mg isotope systematics of chondrules in these meteorites. Olivine, low-Ca pyroxene, and plagioclase within an individual chondrule have similar O-isotope compositions, suggesting crystallization from isotopically uniform melts. The only exceptions are relict grains in two of the chondrules; these grains are 16O-enriched relative to phenocrysts of the host chondrules. Only the FeO-rich chondrule shows a resolvable excesses of 26Mg, corresponding to an inferred initial 26Al/27Al ratio [(26Al/27Al)0] of (2.5 ± 1.6) × 10-6 (±2SE). Combining these results with the previously reported Al-Mg isotope systematics of CR chondrules (Nagashima et al., 2014, Geochem. J. 48, 561), 7 of 22 chondrules (32%) measured show resolvable excesses of 26Mg; the presence of excess 26Mg does not correlate with the FeO content of chondrule silicates. In contrast, virtually all chondrules in weakly metamorphosed (petrologic type 3.0-3.1) unequilibrated ordinary chondrites (UOCs), Ornans-like carbonaceous (CO) chondrites, and the ungrouped carbonaceous chondrite Acfer 094 show resolvable excesses of 26Mg. The inferred (26Al/27Al)0 in CR chondrules with resolvable excesses of 26Mg range from (1.0 ± 0.4) × 10-6 to (6.3 ± 0.9) × 10-6, which is typically lower than (26Al/27Al)0 in the majority of chondrules from UOCs, COs, and Acfer 094. Based on the inferred (26Al/27Al)0, three populations of CR chondrules are recognized; the population characterized by low (26Al/27Al)0 (<3 × 10-6) is dominant. There are no noticeable

  1. Ultra-trace analysis of (41)Ca in urine by accelerator mass spectrometry: an inter-laboratory comparison.

    PubMed

    Jackson, George S; Hillegonds, Darren J; Muzikar, Paul; Goehring, Brent

    2013-10-15

    A (41)Ca interlaboratory comparison between Lawrence Livermore National Laboratory (LLNL) and the Purdue Rare Isotope Laboratory (PRIME Lab) has been completed. Analysis of the ratios assayed by accelerator mass spectrometry (AMS) shows that there is no statistically significant difference in the ratios. Further, Bayesian analysis shows that the uncertainties reported by both facilities are correct with the possibility of a slight under-estimation by one laboratory. Finally, the chemistry procedures used by the two facilities to produce CaF2 for the cesium sputter ion source are robust and don't yield any significant differences in the final result.

  2. THE GALACTIC {sup 26}AL EMISSION MAP AS REVEALED BY INTEGRAL SPI

    SciTech Connect

    Bouchet, Laurent; Jourdain, Elisabeth; Roques, Jean-Pierre

    2015-03-10

    Diffuse emission is often challenging since it is undetectable by most instruments, which are generally dedicated to point-source studies. The {sup 26}Al emission is a good illustration: the only available {sup 26}Al map to date has been released, more than 15 yr ago, thanks to the COMPTEL instrument. However, at the present time, the SPI spectrometer aboard the International Gamma-Ray Astrophysics Laboratory mission offers a unique opportunity to enrich this first result. In this paper, 2 × 10{sup 8} s of data accumulated between 2003 and 2013 are used to perform a dedicated analysis, aiming to deeply investigate the spatial morphology of the {sup 26}Al emission. The data are first compared with several sky maps based on observations at various wavelengths to model the {sup 26}Al distribution throughout the Galaxy. For most of the distribution models, the inner Galaxy flux is compatible with a value of 3.3 × 10{sup −4} photons cm{sup −2} s{sup −1}, while the preferred template maps correspond to young stellar components such as core-collapse supernovae (SNe), Wolf–Rayet stars, and massive AGB stars. To get more details about this emission, an image reconstruction is performed using an algorithm based on the maximum-entropy method. In addition to the inner Galaxy emission, several excesses suggest that some sites of emission are linked to the spiral arm structure. Lastly, an estimation of the {sup 60}Fe line flux, assuming a spatial distribution similar to {sup 26}Al line emission, results in a {sup 60}Fe-to-{sup 26}Al ratio around 0.14, which agrees with the most recent studies and with the SN explosion model predictions.

  3. The Galactic 26Al Emission Map as Revealed by INTEGRAL SPI

    NASA Astrophysics Data System (ADS)

    Bouchet, Laurent; Jourdain, Elisabeth; Roques, Jean-Pierre

    2015-03-01

    Diffuse emission is often challenging since it is undetectable by most instruments, which are generally dedicated to point-source studies. The 26Al emission is a good illustration: the only available 26Al map to date has been released, more than 15 yr ago, thanks to the COMPTEL instrument. However, at the present time, the SPI spectrometer aboard the International Gamma-Ray Astrophysics Laboratory mission offers a unique opportunity to enrich this first result. In this paper, 2 × 108 s of data accumulated between 2003 and 2013 are used to perform a dedicated analysis, aiming to deeply investigate the spatial morphology of the 26Al emission. The data are first compared with several sky maps based on observations at various wavelengths to model the 26Al distribution throughout the Galaxy. For most of the distribution models, the inner Galaxy flux is compatible with a value of 3.3 × 10-4 photons cm-2 s-1, while the preferred template maps correspond to young stellar components such as core-collapse supernovae (SNe), Wolf-Rayet stars, and massive AGB stars. To get more details about this emission, an image reconstruction is performed using an algorithm based on the maximum-entropy method. In addition to the inner Galaxy emission, several excesses suggest that some sites of emission are linked to the spiral arm structure. Lastly, an estimation of the 60Fe line flux, assuming a spatial distribution similar to 26Al line emission, results in a 60Fe-to-26Al ratio around 0.14, which agrees with the most recent studies and with the SN explosion model predictions.

  4. Revisiting 26Al-26Mg systematics of plagioclase in H4 chondrites

    NASA Astrophysics Data System (ADS)

    Telus, M.; Huss, G. R.; Nagashima, K.; Ogliore, R. C.

    2014-06-01

    Zinner and Göpel found clear evidence for the former presence of 26Al in the H4 chondrites Ste. Marguerite and Forest Vale. They assumed that the 26Al-26Mg systematics of these chondrites date "metamorphic cooling of the H4 parent body." Plagioclase in these chondrites can have very high Al/Mg ratios and low Mg concentrations, making these ion probe analyses susceptible to ratio bias, which is inversely proportional to the number of counts of the denominator isotope (Ogliore et al.). Zinner and Göpel used the mean of the ratios to calculate the isotope ratios, which exacerbates this problem. We analyzed the Al/Mg ratios and Mg isotopic compositions of plagioclase grains in thin sections of Ste. Marguerite, Forest Vale, Beaver Creek, and Sena to evaluate the possible influence of ratio bias on the published initial 26Al/27Al ratios for these meteorites. We calculated the isotope ratios using total counts, a less biased method of calculating isotope ratios. The results from our analyses are consistent with those from Zinner and Göpel, indicating that ratio bias does not significantly affect 26Al-26Mg results for plagioclase in these chondrites. Ste. Marguerite has a clear isochron with an initial 26Al/27Al ratio indicating that it cooled to below 450 °C 5.2 ± 0.2 Myr after CAIs. The isochrons for Forest Vale and Beaver Creek also show clear evidence that 26Al was alive when they cooled, but the initial 26Al/27Al ratios are not well constrained. Sena does not show evidence that 26Al was alive when it cooled to below the Al-Mg closure temperature. Given that metallographic cooling rates for Ste. Marguerite, Forest Vale, and Beaver Creek are atypical (>5000 °C/Myr at 500 °C) compared with most H4s, including Sena, which have cooling rates of 10-50 °C/Myr at 500 °C (Scott et al.), we conclude that the Al-Mg systematics for Ste. Marguerite, Forest Vale, and Beaver Creek are the result of impact excavation of these chondrites and cooling at the surface of the

  5. 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('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2758721','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2758721"><span>Antiresorptive Effects of Phytoestrogen Supplements Compared with Estradiol or Risedronate in Postmenopausal Women Using <span class="hlt">41</span><span class="hlt">Ca</span> Methodology</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Weaver, C. M.; Martin, B. R.; Jackson, G. S.; McCabe, G. P.; Nolan, J. R.; McCabe, L. D.; Barnes, S.; Reinwald, S.; Boris, M. E.; Peacock, M.</p> <p>2009-01-01</p> <p>Introduction: Reduction of ovarian estrogen secretion at menopause increases net bone resorption and leads to bone loss. Isoflavones have been reported to protect bone from estrogen deficiency, but their modest effects on bone resorption have been difficult to measure with traditional analytical methods. Methods: In this randomized-order, crossover, blinded trial in 11 healthy postmenopausal women, we compared four commercial sources of isoflavones from soy cotyledon, soy germ, kudzu, and red clover and a positive control of oral 1 mg estradiol combined with 2.5 mg medroxyprogesterone or 5 mg/d oral risedronate (Actonel®) for their antiresorptive effects on bone using novel <span class="hlt">41</span><span class="hlt">Ca</span> methodology. Results: Risedronate and estrogen plus progesterone decreased net bone resorption measured by urinary <span class="hlt">41</span><span class="hlt">Ca</span> by 22 and 24%, respectively (P < 0.0001). Despite serum isoflavone profiles indicating bioavailability of the phytoestrogens, only soy isoflavones from the cotyledon and germ significantly decreased net bone resorption by 9% (P = 0.0002) and 5% (P = 0.03), respectively. Calcium absorption and biochemical markers of bone turnover were not influenced by interventions. Conclusions: Dietary supplements containing genistein-like isoflavones demonstrated a significant but modest ability to suppress net bone resorption in postmenopausal women at the doses supplied in this study over a 50-d intervention period. PMID:19584189</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>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> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013M%26PSA..76.5085P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013M%26PSA..76.5085P"><span>Heterogeneity of Mg Isotopes and Variable ^<span class="hlt">26</span><span class="hlt">Al</span>/^27Al Ratio in FUN CAIs</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Park, C.; Nagashima, K.; Hutcheon, I. D.; Wasserburg, G. J.; Papanastassiou, D. A.; Davis, A. M.; Huss, G. R.; Krot, A. N.</p> <p>2013-09-01</p> <p>We report high-precision Mg-isotope data of individual minerals from the Axtell 2271, BG82DH8, EK1-4-1, C1, TE, and CG14 FUN CAIs, which shows variations in both Mg-isotope ratio and ^<span class="hlt">26</span><span class="hlt">Al</span>/^27Al ratio.</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>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>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/17279768','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17279768"><span>Tissue residues, metabolism, and excretion of radiolabeled sodium chlorate (Na[<span class="hlt">36</span><span class="hlt">Cl</span>]O3) in rats.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hakk, Heldur; Smith, David J; Shappell, Nancy W</p> <p>2007-03-07</p> <p>A novel preharvest technology that reduces certain pathogenic bacteria in the gastrointestinal tracts of food animals involves feeding an experimental sodium chlorate-containing product (ECP) to animals 24-72 h prior to slaughter. To determine the metabolism and disposition of the active ingredient in ECP, four male Sprague-Dawley (approximately 350 g) rats received a single oral dose of sodium [<span class="hlt">36</span><span class="hlt">Cl</span>]chlorate (3.0 mg/kg body weight). Urine, feces, and respired air were collected for 72 h. Radiochlorine absorption was 88-95% of the administered dose, and the major excretory route was the urine. Parent chlorate was the major species of radiochlorine present in urine at 6 h (approximately 98%) but declined sharply by 48 h (approximately 10%); chloride was the only other species of radiochlorine detected. Except for carcass remains (4.6% of dose), skin (3.2%), and gastrointestinal tract (1.3%), remaining tissues contained relatively low quantities of radioactivity, and >98% of radiochlorine remaining in the liver, kidney, and skeletal muscle was chloride. Chlorite instability was demonstrated in rat urine and bovine urine. The previously reported presence of chlorite in excreta of chlorate-dosed rats was shown to be an artifact of the analytical methods employed. Results from this study indicate that chlorate is rapidly absorbed and reduced to chloride, but not chlorite, in rats.</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>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://adsabs.harvard.edu/abs/1997NIMPB.123..259K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1997NIMPB.123..259K"><span>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://adsabs.harvard.edu/abs/2016GeCoA.176..295L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeCoA.176..295L"><span>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>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://www.ars.usda.gov/research/publications/publication/?seqNo115=320549','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=320549"><span>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://pubs.er.usgs.gov/publication/70157344','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70157344"><span>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('https://www.ncbi.nlm.nih.gov/pubmed/27791367','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27791367"><span>Distribution, Identification, and Quantification of Residues after Treatment of Ready-To-Eat Salami with (<span class="hlt">36</span>)<span class="hlt">Cl</span>-Labeled or Nonlabeled Chlorine Dioxide Gas.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Smith, David J; Giddings, J Michael; Herges, Grant R; Ernst, William</p> <p>2016-11-09</p> <p>When ready-to-eat salami was treated in a closed system with (<span class="hlt">36</span>)<span class="hlt">Cl</span>-labeled ClO2 (5.5 mg/100 g of salami), essentially all radioactivity was deposited onto the salami. Administered (<span class="hlt">36</span>)<span class="hlt">Cl</span>O2 was converted to (<span class="hlt">36</span>)<span class="hlt">Cl</span>-chloride ion (>97%), trace levels of chlorate (<2%), and detectable levels of chlorite. In residue studies conducted with nonlabeled ClO2, sodium perchlorate residues (LOQ, 4 ng/g) were not formed when reactions were protected from light. Sodium chlorate residues were present in control (39.2 ± 4.8 ng/g) and chlorine dioxide treated (128 ± 31.2 ng/g) salami. If sanitation occurred under conditions of illumination, detectable levels (3.7 ± 1.5 ng/g) of perchlorate were formed along with greater quantities of sodium chlorate (183.6 ± 75.4 ng/g). Collectively, these data suggest that ClO2 is chemically reduced by salami and that slow-release formulations might be appropriate for applications involving the sanitation of ready-to-eat meat products.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/126696','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/126696"><span>The use of groundwater tracers, including {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>, {delta}{sup 18}O, and {delta}{sup 2}JH, in the study fo the Magothy aquifer, Maryland</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Bond, C.A.; Mignerey, A.C.; Helz, G.R.</p> <p>1995-12-01</p> <p>The recent conclusion of a study of groundwater from the Magothy Formation, Maryland allows for an examination of processes occurring in this aquifer system. Water samples were gathered from a wide area along flow paths estimated from hydrological parameters and analyzed for the major cations and anions, nutrients, and {sup 87}Sr/{sup 86}Sr ratios, in addition to {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>, {delta}{sup 18}O, and {delta}{sup 2}H. Also, three samples that contained anomalously high {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>/Cl ratios were analyzed for {sup 3}H in an attempt to determine possible sources for those readings. A comparison of the results of this study to those of a previous study conducted by this group of the overlying Aquia Aquifer will also be given. The potential of inter-aquifer mixing between the two systems in some areas and of matching {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> and Cl{sup -} values to sea level rise and fall will be discussed.</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>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> </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('http://adsabs.harvard.edu/abs/2016PhRvC..94c4609W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhRvC..94c4609W"><span>Implications for (d ,p ) reaction theory from nonlocal dispersive optical model analysis of 40Ca(d ,p )<span class="hlt">41</span><span class="hlt">Ca</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Waldecker, S. J.; Timofeyuk, N. K.</p> <p>2016-09-01</p> <p>The nonlocal dispersive optical model (NLDOM) nucleon potentials are used for the first time in the adiabatic analysis of a (d ,p ) reaction to generate distorted waves both in the entrance and exit channels. These potentials were designed and fitted by Mahzoon et al. [Phys. Rev. Lett. 112, 162503 (2014), 10.1103/PhysRevLett.112.162503] to constrain relevant single-particle physics in a consistent way by imposing the fundamental properties, such as nonlocality, energy-dependence and dispersive relations, that follow from the complex nature of nuclei. However, the NLDOM prediction for the 40Ca(d ,p )<span class="hlt">41</span><span class="hlt">Ca</span> cross sections at low energy, typical for some modern radioactive beam ISOL (isotope separation online) facilities, is about 70% higher than the experimental data despite being reduced by the NLDOM spectroscopic factor of 0.73. This overestimation comes most likely either from insufficient absorption or due to constructive interference between ingoing and outgoing waves. This indicates strongly that additional physics arising from many-body effects is missing in the widely used current versions of (d ,p ) reaction theories.</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>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('http://adsabs.harvard.edu/abs/1996LPI....27.1257S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1996LPI....27.1257S"><span>New Evidence for <span class="hlt">26</span><span class="hlt">Al</span> in CAI and Chondrules from Type 3 Ordinary Chondrites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Srinivasan, G.; Russell, S. S.; MacPherson, G. J.; Huss, G. R.; Wasserburg, G. J.</p> <p>1996-03-01</p> <p>We have known since 1976 that 26A1 (tl/2 = 7.2 x 105 yrs) was alive in the early solar system, at a level of (<span class="hlt">26</span><span class="hlt">Al</span>/27Al)o z 5 x 10-5 in calcium-aluminum inclusions (CAI). However, several outstanding questions remain. Little evidence for 26A1 has been found in other chondritic material, and none has been found in differentiated meteorites. These results might imply that 26A1 was heterogeneously distributed in the nebula or by mineralogic site in nebular dust, or they might reflect differences in time of formation. There are strict limitations on finding evidence of 26A1 in normal chondrules with bulk Al/Mg ~ 0.1, since even quenched, perfectly preserved, late-stage glasses would have low Al/Mg. Primary plagioclase crystals provide the only possibility, but these only crystallize rarely in melts within the compositional range of normal chondrules. Also, metamorphism can erase the evidence in high-AI/Mg phases. To address these issues, we have conducted a search for chondrules and CAI with high-Al/Mg phases suitable for ion-probe measurement in type 3 ordinary chondrites. Previous work has revealed evidence for <span class="hlt">26</span><span class="hlt">Al</span> in a plagioclase bearing, olivine-pyroxene class from Semarkona (LL3.0; (<span class="hlt">26</span><span class="hlt">Al</span>/27Al)o = 7.7+/-2.1 x 10-6)), a plagioclase-rich object from Bovedy (L3.7?; 2.5+/-1.2 x 10-7), in separated plagioclase from St. Marguerite (H4; 2.0+/-0.6 x 10-7), an isolated hibonite grain from Dhajala (H3.8; 8.4+0.5 x 10-6), and in Al2O3 and hibonite grains ((<span class="hlt">26</span><span class="hlt">Al</span>/27Al)o = 2-5 x 10-5; [GRH, unpublished]) from acid residues of Semarkona, Bishunpur (LL3.1), and Krymka (LL3.1). We have identified and measured Al-Mg isotope systematics in two CAI and seven chondrules from ordinary chondrites of low metamorphic grade and have found clear evidence for 26A1 in both CAI and in two chondrules.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/64310','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/64310"><span>Recent results of measurements of the {sup 14}N(n,p){sup 14}C, {sup 35}Cl(n,p){sup 35}S, {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>(n,p){sup 36}S, and {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>(n,{alpha}){sup 33}P reaction cross sections</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Gledenov, Y.M.; Salatski, V.I.; Sedyshev, P.V.; Sedysheva, M.V.; Koehler, P.E.; Vesna, V.A.; Okunev, I.S.</p> <p>1995-02-05</p> <p>Experiments are reported for measuring the cross section of the {sup 14}N(n,p){sup 14}C reaction over the neutron energy range from thermal energy to 150 keV at the IBR-30 pulsed booster at JNR, Dubna and the WWR-M reactor at INR, Kiev. The reaction cross section values were found for the thermal energy and for the neutron energies of 24 keV, 54 keV, 144 keV. The {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>(n,p){sup 36}S cross section was measured for the neutron energies from thermal energy to approximately 800 keV at the neutron source of LANSCE, Los Alamos. The contributions of the {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>(n,p){sup 36}S and {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>(n,{alpha}){sup 33}P reactions to resonances at 0.9 keV and 1.3 keV were identified. Also, at the WWR-M reactor of PINR, Gatchina, preliminary measurements of the {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>(n,p){sup 36}S cross section at the thermal neutron energy were conducted. The {sup 35}Cl(n,p){sup 35}S reaction cross section was measured at the IBR-30 pulsed booster. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25459713','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25459713"><span>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>2015-02-05</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.</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>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/2007JGRA..11210106W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007JGRA..11210106W"><span>Production of the cosmogenic isotopes 3H, 7Be, 10Be, and <span class="hlt">36</span><span class="hlt">Cl</span> in the Earth's atmosphere by solar and galactic cosmic rays</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Webber, W. R.; Higbie, P. R.; McCracken, K. G.</p> <p>2007-10-01</p> <p>In a follow-up study to the earlier work of Webber and Higbie (2003) on 10Be production in the Earth's atmosphere by cosmic rays, we have calculated the atmospheric production of the cosmogenic isotopes 3H, 7Be, 10Be, and <span class="hlt">36</span><span class="hlt">Cl</span> using the FLUKA Monte Carlo code. This new calculation of atmospheric yields of these isotopes is based on 107 vertically incident protons at each of 24 logarithmically spaced energies from 10 MeV to 10 GeV, 102 times the number used in the earlier calculation, along with the latest cross sections. This permits a study of the production due to solar cosmic rays as well as galactic cosmic rays at lower energies where isotope production is a very sensitive function of energy. Solar cosmic ray spectra are reevaluated for all of the major events occurring since 1956. In terms of yearly production of 10Be, only the February 1956 solar event makes a major contribution. For <span class="hlt">36</span><span class="hlt">Cl</span> these yearly SCR production contributions are 2-5 times larger depending on the solar cosmic ray energy spectra. We have determined the yearly production of 10Be, <span class="hlt">36</span><span class="hlt">Cl</span>, and other cosmogenic isotopes above 65° geomagnetic latitude for the time period 1940-2006 covering six solar 11-year (a) cycles. The average peak-to-peak 11-a amplitude of this yearly production is 1.77. The effects of latitudinal mixing alter these direct polar production values considerably, giving an average peak-to-peak 11-a amplitude of 1.48 for the global average production.</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>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://adsabs.harvard.edu/abs/2015A%26A...578A.113K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015A%26A...578A.113K"><span><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('https://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="https://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>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.; ...</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://pubs.er.usgs.gov/publication/70029102','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70029102"><span>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/835912','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/835912"><span>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://adsabs.harvard.edu/abs/2016EGUGA..1814251Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1814251Y"><span>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('https://www.ncbi.nlm.nih.gov/pubmed/23811127','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23811127"><span>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('https://www.ncbi.nlm.nih.gov/pubmed/25706272','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25706272"><span><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>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.osti.gov/scitech/biblio/5163112','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5163112"><span>Transfer of 45Ca and <span class="hlt">36</span><span class="hlt">Cl</span> at the blood-nerve barrier of the sciatic nerve in rats fed low or high calcium diets</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Wadhwani, K.C.; Murphy, V.A.; Rapoport, S.I. )</p> <p>1991-04-01</p> <p>Unidirectional fluxes of 45Ca, <span class="hlt">36</span><span class="hlt">Cl</span>, and of (3H)mannitol from blood into the sciatic nerve and cerebral cortex were determined from 5- and 15-min uptakes of these tracers after an intravenous (i.v.) bolus injection in awake rats. Rats were fed diets for 8 wk, that had either a low (0.01% wt/wt), normal (0.67%), or high (3%) Ca content. Plasma (Ca) was 32% less and 11% more in rats fed low (LOCA) and high Ca diets (HICA), respectively, than in rats fed a normal Ca diet (CONT). The mean permeability-surface area product (PA) of 45Ca at the blood-nerve barrier was about eightfold higher than at the blood-brain barrier in the same animals and did not differ significantly between groups (greater than 0.05). Mean PA ratios of 45Ca/<span class="hlt">36</span><span class="hlt">Cl</span> for the blood-nerve and blood-brain barriers in CONT rats, 0.52 {plus minus} 0.04 and 0.40 {plus minus} 0.02, respectively, were not significantly different from corresponding ratios in LOCA and HICA groups, and corresponded to the aqueous limiting diffusion ratio (0.45). The authors results show no evidence for concentration-dependent transport of Ca over a plasma (Ca) range of 0.8-1.4 mmol/liter at the blood-nerve barrier of the rat peripheral nerve, and suggest that Ca and Cl exchange slowly between nerve and blood via paracellular pathways.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017QSRv..162..128J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017QSRv..162..128J"><span>Sub-Antarctic glacier extensions in the Kerguelen region (49°S, Indian Ocean) over the past 24,000 years constrained by <span class="hlt">36</span><span class="hlt">Cl</span> moraine dating</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jomelli, Vincent; Mokadem, Fatima; Schimmelpfennig, Irene; Chapron, Emmanuel; Rinterknecht, Vincent; Favier, Vincent; Verfaillie, Deborah; Brunstein, Daniel; Legentil, Claude; Michel, Elisabeth; Swingedouw, Didier; Jaouen, Alain; Aumaitre, Georges; Bourlès, Didier L.; Keddadouche, Karim</p> <p>2017-04-01</p> <p>Similar to many other regions in the world, glaciers in the southern sub-polar regions are currently retreating. In the Kerguelen Islands (49°S, 69°E), the mass balance of the Cook Ice Cap (CIC), the largest ice cap in this region, experienced dramatic shrinking between 1960 and 2013 with retreat rates among the highest in the world. This observation needs to be evaluated in a long-term context. However, data on the past glacier extents are sparse in the sub-Antarctic regions. To investigate the deglaciation pattern since the Last Glacial Maximum (LGM) period, we present the first 13 cosmogenic <span class="hlt">36</span><span class="hlt">Cl</span> surface exposure ages from four sites in the Kerguelen Islands. The <span class="hlt">36</span><span class="hlt">Cl</span> ages from erratic and moraine boulders span from 24.4 ± 2.7 ka to 0.3 ± 0.1 ka. We combined these ages with existing glacio-marine radiocarbon ages and bathymetric data to document the temporal and spatial changes of the island's glacial history. Ice began to retreat on the main island before 24.4 ± 2.7 ka until around the time of the Antarctic Cold Reversal (ACR) period (∼14.5-12.9 ka), during which the Bontemps moraine was formed by the advance of a CIC outlet glacier. Deglaciation continued during the Holocene probably until 3 ka with evidence of minor advances during the last millennium. This chronology is in pace with major changes in δ18O in a recent West Antarctica ice core record, showing that Kerguelen Islands glaciers are particularly sensitive and relevant to document climate change in the southern polar regions.</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>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('http://adsabs.harvard.edu/abs/2015ApJ...809...31G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015ApJ...809...31G"><span>Inferred Initial <span class="hlt">26</span><span class="hlt">Al</span>/27Al Ratios in Presolar Stardust Grains from Supernovae are Higher than Previously Estimated</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Groopman, Evan; Zinner, Ernst; Amari, Sachiko; Gyngard, Frank; Hoppe, Peter; Jadhav, Manavi; Lin, Yangting; Xu, Yuchen; Marhas, Kuljeet; Nittler, Larry R.</p> <p>2015-08-01</p> <p>We performed an in-depth exploration of the Al-Mg system for presolar graphite, SiC, and Si3N4 grains found to contain large excesses of 26Mg, indicative of the initial presence of live <span class="hlt">26</span><span class="hlt">Al</span>. Ninety of the more than 450 presolar grains processed in this study contain well-correlated {δ }26{Mg}{/}24{Mg} and 27Al/24Mg ratios, derived from Nano-scale Secondary Ion Mass Spectrometer depth profiles, whose isochron-like regression lines yield inferred initial {}<span class="hlt">26</span>{<span class="hlt">Al</span>}{/}27{Al} ratios that, on average, are ˜1.5-2 times larger than the ratios previously reported for the grains. The majority of presolar graphite and SiC grains are heavily affected by Al contamination, resulting in large negative {δ }26{Mg}{/}24{Mg} intercepts of the isochron lines. Al contamination is potentially due to etching of the grains’ surfaces and subsequent capture of dissolved Al during the acid dissolution of their meteorite host rocks. From the isochron fits, the magnitude of Al contamination was quantified for each grain. The amount of Al contamination on each grain was found to be random and independent of grain size, following a uniform distribution with an upper bound at 59% contamination. The Al contamination causes conventional whole-grain estimates to underpredict the initial {}<span class="hlt">26</span>{<span class="hlt">Al</span>}{/}27{Al} ratios. The presolar grains with the highest {}<span class="hlt">26</span>{<span class="hlt">Al</span>}{/}27{Al} ratios are from Type II supernovae whose isochron-derived initial {}<span class="hlt">26</span>{<span class="hlt">Al</span>}{/}27{Al} ratios greatly exceed those predicted in the He/C and He/N zones of SN models.</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('https://www.osti.gov/scitech/biblio/6967766','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6967766"><span>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('https://www.osti.gov/scitech/biblio/21305099','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21305099"><span>EARLY SOLAR NEBULA CONDENSATES WITH CANONICAL, NOT SUPRACANONICAL, INITIAL {sup <span class="hlt">26</span>}<span class="hlt">Al</span>/{sup 27}Al RATIOS</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>MacPherson, G. J.; Bullock, E. S.; Janney, P. E.; Wadhwa, M.; Kita, N. T.; Ushikubo, T.; Davis, A. M.; Krot, A. N.</p> <p>2010-03-10</p> <p>The short-lived radionuclide {sup <span class="hlt">26</span>}<span class="hlt">Al</span> existed throughout the solar nebula 4.57 Ga ago, and the initial abundance ratio ({sup <span class="hlt">26</span>}<span class="hlt">Al</span>/{sup 27}Al){sub 0}, as inferred from magnesium isotopic compositions of calcium-aluminum-rich inclusions (CAIs) in chondritic meteorites, has become a benchmark for understanding early solar system chronology. Internal mineral isochrons in most CAIs measured by secondary ion mass spectrometry (SIMS) give ({sup <span class="hlt">26</span>}<span class="hlt">Al</span>/{sup 27}Al){sub 0} {approx} (4-5) x 10{sup -5}, called 'canonical'. Some recent high-precision analyses of (1) bulk CAIs measured by multicollector inductively coupled plasma mass spectrometry (MC-ICPMS), (2) individual CAI minerals and their mixtures measured by laser-ablation MC-ICPMS, and (3) internal isochrons measured by multicollector (MC)-SIMS indicated a somewhat higher 'supracanonical' ({sup <span class="hlt">26</span>}<span class="hlt">Al</span>/{sup 27}Al){sub 0} ranging from (5.85 {+-} 0.05) x 10{sup -5} to >7 x 10{sup -5}. These measurements were done on coarse-grained Type B and Type A CAIs that probably formed by recrystallization and/or melting of fine-grained condensate precursors. Thus the supracanonical ratios might record an earlier event, the actual nebular condensation of the CAI precursors. We tested this idea by performing in situ high-precision magnesium isotope measurements of individual minerals in a fine-grained CAI whose structures and volatility-fractionated trace element abundances mark it as a primary solar nebula condensate. Such CAIs are ideal candidates for the fine-grained precursors to the coarse-grained CAIs, and thus should best preserve a supracanonical ratio. Yet, our measured internal isochron yields ({sup <span class="hlt">26</span>}<span class="hlt">Al</span>/{sup 27}Al){sub 0} = (5.27 {+-} 0.17) x 10{sup -5}. Thus our data do not support the existence of supracanonical ({sup <span class="hlt">26</span>}<span class="hlt">Al</span>/{sup 27}Al){sub 0} = (5.85-7) x 10{sup -5}. There may not have been a significant time interval between condensation of the CAI precursors and their subsequent melting into coarse-grained CAIs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003GeCoA..67.4529S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003GeCoA..67.4529S"><span>Origin and history of waters associated with coalbed methane: 129I, <span class="hlt">36</span><span class="hlt">Cl</span>, and stable isotope results from the Fruitland Formation, CO and NM</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Snyder, Glen T.; Riese, Walter C."Rusty"; Franks, Stephen; Fehn, Udo; Pelzmann, William L.; Gorody, Anthony W.; Moran, Jean E.</p> <p>2003-12-01</p> <p>The Fruitland Formation of the San Juan Basin was deposited during the late Cretaceous and is associated with significant reservoirs of coalbed methane (CBM). The purpose of this study is to determine the origin and history of waters associated with the formation, using long-lived cosmogenic and stable isotope systems. Ratios of 129I/I and stable isotope values (δD and δ 18O) were determined in waters from close to 100 wells, <span class="hlt">36</span><span class="hlt">Cl</span>/Cl ratios for a subset of these samples. A significant group of samples has 129I/I ratios between 100 × 10 -15 and 200 × 10 -15, indicating minimum iodine ages close to 60 Ma. If these ages are corrected for the addition of fissiogenic 129I, they are compatible with the depositional age of the Fruitland Formation (Late Cretaceous). Several sets of waters are clearly present within the data. A group dominated by infiltration of recent surface waters is restricted to the uplifted basin margins, with a lateral extent of less than 5 km from outcrop, and is characterized by 129I/I ratios in excess of 1500 × 10 -15 and meteoric δD, δ 18O, and <span class="hlt">36</span><span class="hlt">Cl</span>/Cl signatures. The rest of the basin is characterized by several subsets of formation waters which have undergone variable degrees of iodine enrichment through diagenesis as well as variable degrees of dilution. The first subgroup is found in coals of relatively low vitrinite reflectance and moderate enrichment of iodine. This subgroup predominantly consists of entrapped pore fluids, although it may also contain waters which infiltrated the coals at the time of the Laramide uplift, between 25 and 30 Ma. A second subgroup consists of formation waters associated with coals of high vitrinite reflectance. Despite subsequent uplift, the high iodine concentrations and low 129I/I ratios of this subgroup, as well as a moderate depletion of deuterium relative to 18O, suggest that these waters were not significantly altered since the time when diagenetic reactions occurred in the deepest portion of the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AGUFM.S43A1060S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AGUFM.S43A1060S"><span>Large Earthquake Repeat on Normal Faults: Insights from dense in-situ <span class="hlt">36</span><span class="hlt">Cl</span> Exposure Dating of Limestone Fault Scarps, Central Apennines, 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.; Benedetti, L.; Manighetti, I.</p> <p>2007-12-01</p> <p>The only chance to learn how major earthquakes have repeated in the past on major active faults is to analyze their surface geological record, if any. We analyze such a record on 11 active normal faults to seek identifying, dating and measuring the large earthquake ruptures that have broken these faults in the last 10-20 kyrs, and determine how these major ruptures have followed in space and time on each fault and from one fault to another. As large earthquakes repeat on a normal fault, the fault plane is progressively exhumed and exposed at the free air, forming an escarpment at the surface. Provided that this escarpment is preserved from erosion, its surface holds the complete record of the successive ruptures (and possible aseismic slip) as they have broken the ground surface. We have started to analyze such a record on 11 neighboring, likely interacting active faults in the Fucino area, Central Italy, where seismic activity can be devastating (1915, M7 Avezzano earthquake, 30 000 casualties). Faults offset limestone rocks and form several hundred meters high cumulative escarpments, whose youngest parts (10-20 kyrs) are well preserved in the form of 10-20 m high, steep scarps running along the fault lengths (10-20 km). The Holocene seismic slip history of the faults can be recovered from base-to-top continuous in-situ <span class="hlt">36</span><span class="hlt">Cl</span> exposure dating of the limestone scarps (Benedetti et al. 2002, 2003; Palumbo et al. 2004). To reach that objective, we have sampled the faults in two different ways: two faults (Magnola and Roccapreturo) were sampled at several, regularly spaced sites along their length, so that to recover the earthquake slip variability in both space and time. Nine other faults (Fiamigniano, Campo-Felice, Velino, Tre- Monti, Trasacco, Parasano, San Sebastiano, Castel di Ieri, Roccacasale) were sampled at one single spot along their length, so that to examine the possible earthquake interactions within the entire fault system. Doing so, we have collected one</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>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://pubs.er.usgs.gov/publication/70030141','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70030141"><span>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('https://www.osti.gov/scitech/biblio/21199603','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21199603"><span>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('https://www.osti.gov/scitech/biblio/21448880','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21448880"><span>{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>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://adsabs.harvard.edu/abs/2016EGUGA..18.6633R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.6633R"><span>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/2014AGUFM.T13C4671J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.T13C4671J"><span>Seismic slip history of the Aterno-Sulmona fault system in central Apennines (Italy) using in situ produced <span class="hlt">36</span><span class="hlt">Cl</span> cosmic ray 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>Jim, T.; Benedetti, L. C.; Bruno, P.; Visini, F.; Aumaitre, G.; Bourles, D. L.</p> <p>2014-12-01</p> <p>Acquiring long records of past earthquakes on a large population of faults is a key step to understand how strain release along those fault systems varies spatially and temporally.In central Italy, NE-SW extension (~4 mm/yr) is accommodated on a wide normal fault system (50 x 100km). Benedetti et al. (2013) found that 7 of these faults, belonging to the Fucino fault system, have their seismic activity synchronized during short (less than 1 ka) paroxysmal phases of activity. <span class="hlt">36</span><span class="hlt">Cl</span> measurements and rare earth elements (REE) concentrations were used to reconstruct the seismic slip history of four major faults belonging to an adjacent 30-km-long fault system, the Aterno-Sulmona fault system, at the southeastward tip of the Paganica fault that ruptured during the 2009 L'Aquila earthquake.The preliminary results suggest that 3-7 seismic events have occurred on each fault over the last 11 ka (from NE to SW the Roccapreturo, the Castel di Ieri, the Roccacasale and the Pizzalto faults), with 50 cm to 2 m of associated slip per event. These events appear clustered within intense period of seismic activity lasting less than 1ka (2 to 4 seismic events) separated by 2 to 3 ka periods with no seismic events. The most recent recorded paroxysmal activity occurred about 2.5 ka ago with all four studied faults rupturing in more than 15 earthquakes over a period lasting less than 1ka. These results thus suggest that, as already observed on the Fucino fault system, the seismic activity of the Aterno-Sulmona fault system is also synchronized during short periods of paroxysmal seismic activity.When clustering periods are compared, the seismic activity of the Fucino and the Aterno-Sulmona fault system, are, however, apparently unsynchronized since the most recent clustering period for the Aterno-Sulmona system corresponds to a quiescent period for the Fucino fault system.</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>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/2015GeCoA.158..245D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015GeCoA.158..245D"><span>Isotopic mass fractionation laws for magnesium and their effects on <span class="hlt">26</span><span class="hlt">Al</span>-26Mg systematics in solar system materials</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Davis, Andrew M.; Richter, Frank M.; Mendybaev, Ruslan A.; Janney, Philip E.; Wadhwa, Meenakshi; McKeegan, Kevin D.</p> <p>2015-06-01</p> <p>Magnesium isotope ratios are known to vary in solar system objects due to the effects of <span class="hlt">26</span><span class="hlt">Al</span> decay to 26Mg and mass-dependent fractionation, but anomalies of nucleosynthetic origin must also be considered. In order to infer the amount of enhancement of 26Mg/24Mg due to <span class="hlt">26</span><span class="hlt">Al</span> decay or to resolve small nucleogenetic anomalies, the exact relationship between 26Mg/24Mg and 25Mg/24Mg ratios due to mass-dependent fractionation, the mass-fractionation "law", must be accurately known so that the 25Mg/24Mg ratio can be used to correct the 26Mg/24Mg ratio for mass fractionation. Mass-dependent fractionation in mass spectrometers is reasonably well characterized, but not necessarily fully understood. It follows a simple power fractionation law, sometimes referred to as the "exponential law". In contrast, mass fractionation in nature, in particular that due to high temperature evaporation that likely caused the relatively large effects observed in calcium-, aluminum-rich inclusions (CAIs), is reasonably well understood, but mass-fractionation laws for magnesium have not been explored in detail. The magnesium isotopic compositions of CAI-like evaporation residues produced in a vacuum furnace indicate that the slope on a log 25Mg/24Mg vs. log 26Mg/24Mg plot is ∼0.5128, and different from those predicted by any of the commonly used mass-fractionation laws. Evaporation experiments on forsterite-rich bulk compositions give exactly the same slope, indicating that the measured mass-fractionation law for evaporation of magnesium is applicable to a wide range of bulk compositions. We discuss mass-fractionation laws and the implications of the measured fractionation behavior of magnesium isotopes for <span class="hlt">26</span><span class="hlt">Al</span>-26Mg chronology.</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>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://pubs.er.usgs.gov/publication/70029271','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70029271"><span>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/2016PhRvC..94f5804A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhRvC..94f5804A"><span>Experimental study of the astrophysically important 23Na(α ,p )26Mg and 23Na(α ,n )<span class="hlt">26</span><span class="hlt">Al</span> reactions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Avila, M. L.; Rehm, K. E.; Almaraz-Calderon, S.; Ayangeakaa, A. D.; Dickerson, C.; Hoffman, C. R.; Jiang, C. L.; Kay, B. P.; Lai, J.; Nusair, O.; Pardo, R. C.; Santiago-Gonzalez, D.; Talwar, R.; Ugalde, C.</p> <p>2016-12-01</p> <p>The 23Na(α ,p )26Mg and 23Na(α ,n )<span class="hlt">26</span><span class="hlt">Al</span> reactions are important for our understanding of the <span class="hlt">26</span><span class="hlt">Al</span> abundance in massive stars. The aim of this work is to report on a direct and simultaneous measurement of these astrophysically important reactions using an active target system. The reactions were investigated in inverse kinematics using 4He as the active target gas in the detector. We measured the excitation functions in the energy range of about 2 to 6 MeV in the center of mass. We have found that the cross sections of the 23Na(α ,p )26Mg and the 23Na(α ,n )<span class="hlt">26</span><span class="hlt">Al</span> reactions are in good agreement with previous experiments and with statistical-model calculations. The astrophysical reaction rate of the 23Na(α ,n )<span class="hlt">26</span><span class="hlt">Al</span> reaction has been reevaluated and it was found to be larger than the recommended rate.</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>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> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22167129','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22167129"><span>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('https://www.ncbi.nlm.nih.gov/pubmed/19224038','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19224038"><span>The use of multiple probe molecules for the study of the acid-base properties of aluminium hydroxyfluoride having the hexagonal tungsten bronze structure: FTIR and [<span class="hlt">36</span><span class="hlt">Cl</span>] radiotracer studies.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Dambournet, Damien; Leclerc, Hervé; Vimont, Alexandre; Lavalley, Jean-Claude; Nickkho-Amiry, Mahmood; Daturi, Marco; Winfield, John M</p> <p>2009-03-07</p> <p>The combination of several probe molecules has enabled the construction of a detailed picture of the surface of aluminium hydroxyl fluoride, AlF(2.6)(OH)(0.4), which has the hexagonal tungsten bronze (HTB) structure. Using pyridine as a probe leads to features at 1628 cm(-1), ascribed to very strong Lewis acid sites, and at 1620-1623 cm(-1), which is the result of several different types of Lewis sites. This heterogeneity is indicated also from CO adsorption at 100 K; the presence of five different types of Lewis site is deduced and is suggested to arise from the hydroxylated environment. Brønsted acid sites of medium strength are indicated by adsorption of lutidine and CO. Adsorption of lutidine occurs at OH groups, which are exposed at the surface and CO reveals that these OH groups have a single environment that can be correlated with their specific location inside the bulk, assuming that the surface OH group may reflect the bulk OH periodicity. A correlation between the data obtained from CO and pyridine molecules has been established using co-adsorption experiments, which also highlight the inductive effect produced by pyridine. Adsorption of the strong Brønsted acid, anhydrous hydrogen chloride, detected by monitoring the beta(-) emission of [(<span class="hlt">36</span>)<span class="hlt">Cl</span>]-HCl at the surface, indicates that surface hydroxyl groups can behave also as a Brønsted base and that H(2)O-HCl interactions, either within the hexagonal channels or at the surface are possible. Finally, the formation of strongly bound H(<span class="hlt">36</span>)<span class="hlt">Cl</span> as a result of the room temperature dehydrochlorination of [(<span class="hlt">36</span>)<span class="hlt">Cl</span>]-labelled tert-butyl chloride provides additional evidence that HTB-AlF(2.6)(OH)(0.4) can behave as a Lewis acid.</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>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> </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://pubs.er.usgs.gov/publication/70094758','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70094758"><span>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/2001QuRes..55..235C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001QuRes..55..235C"><span>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://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Clapp, Erik M.; Bierman, Paul R.; Nichols, Kyle K.; Pavich, Milan; Caffee, Marc</p> <p>2001-03-01</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/2001RScI...72..822W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001RScI...72..822W"><span>Study of the 27Al(n,2n)<span class="hlt">26</span><span class="hlt">Al</span> reaction and its potential for ion-temperature measurements (abstract)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wallner, A.; Chuvaev, S. V.; Filatenkov, A. A.; Ikeda, Y.; Kutschera, W.; Vonach, H.</p> <p>2001-01-01</p> <p>A detailed measurement of the 27Al(n,2n)<span class="hlt">26</span><span class="hlt">Al</span> reaction cross sections was performed in the near-threshold region (Eth=13.54 MeV), and its possible applicability for ion temperature measurements was investigated. The production of the long-lived radionuclide <span class="hlt">26</span><span class="hlt">Al</span> (t1/2=7.2×105 a) is of considerable interest to the fusion reactor program. Particularly long-lived radionuclides may lead to a significant long-term waste-disposal. Al-containing materials and Si carbide are candidate materials for fusion-reactor systems. The Al(n,2n) reaction and the two step process 28Si(n,np+d)27Al(n,2n) are the dominating processes for the formation of <span class="hlt">26</span><span class="hlt">Al</span> in a fusion reactor.1 The 27Al(n,2n)<span class="hlt">26</span><span class="hlt">Al</span> reaction is expected to vary strongly with neutron energy above threshold. An accurate description of the excitation function is necessary to estimate the production of <span class="hlt">26</span><span class="hlt">Al</span> in a typical D-T fusion environment. From the existing data on cross sections it was not possible to produce an unambiguous excitation function. We started therefore a project to determine this excitation function more accurately. It has been pointed out by Smither and Greenwood2 that the 27Al(n,2n)<span class="hlt">26</span><span class="hlt">Al</span> reaction can be used as a monitor to determine the ion temperature in a D-T fusion plasma. This method makes use of the neutron energy distribution as a sensitive function of the plasma ion temperature. The temperature sensitivity is most pronounced if the excitation function is strongly nonlinear and if the threshold falls within the energy region of the emitted neutrons: For the 27Al(n,2n)<span class="hlt">26</span><span class="hlt">Al</span> reaction the threshold lies at 13.54 MeV and the (n,2n) reaction is expected to a strongly varying function of the neutron energy near threshold. Al samples were irradiated with 14 MeV neutrons generated via the T(d,n)4He reaction at three different laboratories under different conditions. The produced <span class="hlt">26</span><span class="hlt">Al</span> was measured using the extremely sensitive method of accelerator mass spectrometry (AMS). <span class="hlt">26</span><span class="hlt">Al</span>/27Al isotope ratios as low as</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>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://adsabs.harvard.edu/abs/2000NIMPB.172..112S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000NIMPB.172..112S"><span>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/2012GeCoA..77..415B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012GeCoA..77..415B"><span><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://adsabs.harvard.edu/abs/2016EGUGA..18.9718N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.9718N"><span><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://www.osti.gov/scitech/servlets/purl/277041','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/277041"><span>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('https://www.osti.gov/scitech/biblio/20863750','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/20863750"><span>Measurement of {sup 25}Mg(p, {gamma}){sup <span class="hlt">26</span>}<span class="hlt">Al</span>{sup g} resonance strengths via accelerator mass spectrometry</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Arazi, A.; Niello, J. O. Fernandez; Faestermann, T.; Knie, K.; Korschinek, G.; Poutivtsev, M.; Rugel, G.; Richter, E.; Wallner, A.</p> <p>2006-08-15</p> <p>The strengths of resonances located at center-of-mass energies of E{sub c.m.}=189, 304, 374, and 418 keV for the {sup 25}Mg(p,{gamma}) reaction have been measured for the first time with an off-line method: Mg targets were firstly activated with protons at the resonance energies and the produced {sup <span class="hlt">26</span>}<span class="hlt">Al</span>{sup g} nuclei were counted by means of highly sensitive accelerator mass spectrometry (AMS). Thus, the production of {sup <span class="hlt">26</span>}<span class="hlt">Al</span> in its ground state is determined independently from the {gamma}-decay branching ratio. While the 304, 374, and 418 keV resonances show fair agreement with previous measurements, the 189 keV resonance yield a significantly less strength. In addition, an experimental upper limit for the E{sub c.m.}=92 keV resonance was determined.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2000NIMPB.172..767B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000NIMPB.172..767B"><span>Dating of prehistoric caves sediments and flints using 10Be and <span class="hlt">26</span><span class="hlt">Al</span> in quartz from Tabun Cave (Israel): Progress report</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Boaretto, E.; Berkovits, D.; Hass, M.; Hui, S. K.; Kaufman, A.; Paul, M.; Weiner, S.</p> <p>2000-10-01</p> <p>There is an important need to develop additional dating methods beyond the 14C limit and independent of thermoluminescence (TL) and electron spin resonance (ESR). We propose to apply the method of burial dating to prehistoric sites using the decay of in situ produced radioisotopes 10Be and <span class="hlt">26</span><span class="hlt">Al</span>. The Tabun Cave, Mt. Carmel (Israel) has a sedimentary sequence which represents the type section for about the last 800,000 years in the Levant. The sediments in the cave are mainly of aeolian origin and are rich in quartz. Flint tools are also found in the sediments. Sediment samples and flint tools were selected from the same layer. Physical and chemical procedures to extract 10Be and <span class="hlt">26</span><span class="hlt">Al</span> atoms from the quartz fraction of the sediments and from the flint samples were developed, while measuring the natural Al levels as a monitor of the atmospheric component of the cosmogenic nuclides. AMS measurements were performed at the 14UD Pelletron Koffler Accelerator Laboratory, Weizmann Institute, and sensitivities of the order of 1×10 -14, in isotopic abundances for both 10Be and <span class="hlt">26</span><span class="hlt">Al</span> respectively (corresponding to ˜5 × 10 5 atoms) were obtained. First, measurements of a number of Tabun Cave sediment samples and flints show that 10Be and <span class="hlt">26</span><span class="hlt">Al</span> analyses have the potential for dating prehistoric cave sediments, provided problems relating to the presence of relatively large amounts of stable Al can be solved, as well as obtaining a better understanding of the burial history of the flints prior to being brought into the cave.</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>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/2013JSSCh.204..233D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013JSSCh.204..233D"><span>Phase polymorphism of novel [Ru(NH3)6](ClO4)3—Comparison with [Ru(NH3)6](BF4)3. Part II</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dołęga, Diana; Mikuli, Edward; Górska, Natalia; Inaba, Akira; Hołderna-Natkaniec, Krystyna; Nitek, Wojciech</p> <p>2013-08-01</p> <p>[Ru(NH3)6](ClO4)3 undergoes two phase transitions at: TC1=290.3 K and TC2=74.8 K , thus exhibits three crystalline phases in the temperature range of 5-310 K. For the detected phase transitions, thermal effects were determined. Fourier transform far- and middle-infrared spectra (FT-FIR and FT-MIR), recorded at 8-350 K, suggest that reorientational motions of the NH3 ligands are very fast (τR≈10-12 s above TC1) and are significantly slowed down below TC2. X-ray single crystal diffraction (XRSCD) measurements revealed that in the high temperature phase (above TC1) the compound belongs to the cubic Fm3barm (No. 225) space group, whereas in the intermediate phase the unit cell parameter doubles and the space group is Ia3bar(No. 206). 1H NMR studies revealed that the following reorientational motions are liberated during heating: three-fold reorientation of NH3 ligands, three-fold reorientation of the entire [Ru(NH3)6]3+ cation, and isotropic reorientation of this cation. In the high temperature phase I the cations perform isotropic reorientations with the estimated activation energy equal to ca. 30.1 kJ mol-1. Comparison with adequate results obtained earlier for [Ru(NH3)6](BF4)3 and for other similar compounds was made and general regularities were drawn.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017E%26PSL.457..271R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017E%26PSL.457..271R"><span>Inner gorges incision history: A proxy for deglaciation? Insights from Cosmic Ray Exposure dating (10Be and <span class="hlt">36</span><span class="hlt">Cl</span>) of river-polished surfaces (Tinée River, SW Alps, France)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rolland, Y.; Petit, C.; Saillard, M.; Braucher, R.; Bourlès, D.; Darnault, R.; Cassol, D.</p> <p>2017-01-01</p> <p>10Be and <span class="hlt">36</span><span class="hlt">Cl</span> Cosmic Ray Exposure (CRE) dating performed on river polished surfaces of river gorges in a mountain-to-sea river system in the French SW Alps highlights transient erosional events involving incision rates >10 mm a-1. These events took place during the last two major deglaciation phases following (1) the Last Glacial Maximum (LGM) at 16-14 ka, (2) the Younger Dryas at 8-11 ka, and during the warm and humid Holocene climatic optimum at 4-5 ka. These periods of high incision rates (3- > 30 mma-1) alternated with periods of low incision rates (<1 mm a-1), which probably correspond to a long-term equilibrium between incision and relative uplift. The Alpine river staircase shape profiles evidence local and transient responses that are ascribed to cumulate disequilibrium after the long-time-spanned glaciations. After each glaciation, rivers rush down to get closer to their equilibrium profile. Incision is amplified both by the sediment discharge due to the erosion of moraines and by landslides triggered by the glacier retreat.</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>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>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://www.osti.gov/scitech/servlets/purl/10650','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/10650"><span>Status of cross-section data for gas production from vanadium and {sup <span class="hlt">26</span>}<span class="hlt">AL</span> from silicon carbide in a D-T fusion reactor.</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Gomes, I. C.</p> <p>1998-08-11</p> <p>Current designs of fusion-reactor systems seek to use radiation-resistant, low-activation materials that support long service lifetimes and minimize radioactive-waste problems after decommissioning. Reliable assessment of fusion materials performance requires accurate neutron-reaction cross sections and radioactive-decay constants. The problem areas usually involve cross sections since decay parameters tend to be better known. The present study was motivated by two specific questions: (i) Why are the {sup 51}V(n,np){sup 50}Ti cross section values in the ENDF/B-VI library so large (a gas production issue)? (ii) How well known are the cross sections associated with producing 7.4 x 10{sup 5} y {sup <span class="hlt">26</span>}<span class="hlt">Al</span> in silicon carbide by the process {sup 28}Si(n,np+d){sup 27} Al(n,2n){sup <span class="hlt">26</span>}<span class="hlt">Al</span> (a long-lived radioactivity issue)? The energy range 14-15 MeV of the D-T fusion neutrons is emphasized. Cross-section error bars are needed so that uncertainties in the gas and radioactivity generated over the lifetime of a reactor can be estimated. We address this issue by comparing values obtained from prominent evaluated cross-section libraries. Small differences between independent evaluations indicate that a physical quantity is well known while the opposite signals a problem. Hydrogen from {sup 51}V(n,p){sup 51}Ti and helium from {sup 51}V(n,{alpha}){sup 48}Sc are also important sources of gas in vanadium, so they too were examined. We conclude that {sup 51}V(n,p){sup 51}Ti is adequately known but {sup 51}V(n,np+d){sup 50}Ti is not. The status for helium generation data is quite good. Due to recent experimental work, {sup 27}Al(n,2n){sup <span class="hlt">26</span>}<span class="hlt">Al</span> seems to be fairly well known. However, the situation for {sup 28}Si(n,np+d){sup 27}Al remains unsatisfactory.</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>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>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://adsabs.harvard.edu/abs/2017Geomo.281...53D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017Geomo.281...53D"><span>Early to Late Pleistocene history of debris-flow fan evolution in western Death Valley (California) using 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>Dühnforth, Miriam; Densmore, Alexander L.; Ivy-Ochs, Susan; Allen, Philip; Kubik, Peter W.</p> <p>2017-03-01</p> <p>Debris-flow fans with depositional records over several 105 years may be useful archives for the understanding of fan construction by debris flows and post-depositional surface modification over long timescales. Reading these archives, however, requires that we establish the temporal and spatial pattern of debris-flow activity over time. We used a combination of geomorphic mapping of fan surface characteristics, digital topographic analysis, and cosmogenic radionuclide dating using 10Be and <span class="hlt">26</span><span class="hlt">Al</span> to study the evolution of the Warm Springs fan on the west side of southern Death Valley, California. The 10Be concentrations yield dates that vary from 989 ± 43 to 595 ± 17 ka on the proximal fan and between 369 ± 13 and 125 ± 5 ka on distal fan surfaces. The interpretation of these results as true depositional ages though is complicated by high inheritance with a minimum of 65 ka measured at the catchment outlet and of at least 125 ka at the distal fan. Results from the <span class="hlt">26</span><span class="hlt">Al</span> measurements suggest that most sample locations on the fan surfaces underwent simple exposure and were not affected by complex histories of burial and re-exposure. This implies that Warm Springs fan is a relatively stable landform that underwent several 105 years of fan aggradation before fan head incision caused abandonment of the proximal and central fan surfaces and deposition continued on a younger unit at the distal fan. We show that the primary depositional debris-flow morphology is eliminated over a time scale of less than 105 years, which prevents the delineation of individual debris flows as well as the precise reconstruction of lateral shifts in deposition as we find it on younger debris-flow fans. Secondary post-depositional processes control subsequent evolution of surface morphology with the dissection of planar surfaces while smoothing of convex-up interfluves between incised channels continues through time.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/20863727','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/20863727"><span>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> </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>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://adsabs.harvard.edu/abs/2007NIMPB.259..351F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007NIMPB.259..351F"><span>Chemical procedure for extracting 129I, 60Fe and <span class="hlt">26</span><span class="hlt">Al</span> from marine sediments: Prospects for detection of a ˜2.8 My old supernova</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fitoussi, Caroline; Raisbeck, Grant M.</p> <p>2007-06-01</p> <p>For the past three years, we have been developing a procedure to measure carrier-free 129I/I in gram size quantities of marine sediments containing microgram quantities of iodine. Potential applications involve dating of old (>10 My) sediments and the detection of 129I (t1/2 = 15.7 My) from a purported supernova (SN) explosion ˜2.8 million years ago, that has been inferred from a 60Fe (t1/2 = 1.5 My) signal in a deep-sea ferromanganese crust [K. Knie, G. Korschinek, T. Faestermann, E.A. Dorfi, G. Rugel, A. Wallner, Phys. Rev. Lett. 93 (2004) 171103]. The procedure consists in washing the sediment with a NH2OH · HCl HOAc mixture, extraction of iodine from the organic phase with TMAH, separation and purification using anion-exchange chromatography, and coprecipitation as AgI Ag2O. We realized the washing step, which extracts authigenic iron and aluminum, could also be used to measure 60Fe/56Fe and <span class="hlt">26</span><span class="hlt">Al</span>/27Al in this phase of the same sediment sample. We outline here the chemical procedures developed, and briefly comment on their possible application to the supernova problem. We also point out a large discrepancy between the theoretically calculated 129I/127I ratio in pre-anthropogenic marine sediments, and that derived from experimental measurements.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017QSRv..157..141K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017QSRv..157..141K"><span>Cosmogenic 10Be and <span class="hlt">26</span><span class="hlt">Al</span> exposure ages of glaciations in the Frankland Range, southwest Tasmania reveal a limited MIS-2 ice advance</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kiernan, Kevin; Fink, David; McConnell, Anne</p> <p>2017-02-01</p> <p>New mapping of the glacial geomorphology coupled with 10Be and <span class="hlt">26</span><span class="hlt">Al</span> exposure age dating of moraines on the flanks of the Frankland Range in south west Tasmania indicate that glacier extent during MIS-2 was far smaller than during earlier glaciations with the ice cover being confined to only the uppermost cirques of the range. Moraines further down the range flanks, ∼50-150 m lower in altitude than the MIS-2 dated advance, indicate that glaciers were only slightly larger during earlier glaciations and, depending on the interpretation of their exposure ages, may range from MIS 7 to MIS 12. These older moraines are nested inside the maximum ice limits of an even more ancient and extensive glaciation, defined by degraded valley floor moraines and coalescing glacio-fluvial fans that remain undated but appear no younger than MIS 12. Patterns of glacial erosion and moraine deposition on the Frankland Range suggest that the more recent glaciations were increasingly influenced by the erosional morphology initiated by earlier glaciers. Microclimatic differences resulting from this earlier glacial topography were particularly influential determinants of glaciation during MIS 2. These results are consistent with emerging evidence from studies of other ranges in southwest Tasmania.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.T41B2895Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.T41B2895Y"><span>Uplift rates of the marine terraces in the south coast of Japan 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>Yokoyama, Y.; Nagano, G.; Nakamura, A.; Maemoku, H.; Miyairi, Y.; Matsuzaki, H.</p> <p>2015-12-01</p> <p>Marine terraces are low-relief platforms located along coastal areas. They are formed by waves action with the changes in the relative sea level (RSL) that is affected by combined effects of the eustatic sea level (ESL) and the tectonic movements (e.g. uplift, subsidence and isostatic effect). Therefore, determining the ages and the elevations of the marine terraces allows us to reconstruct the ESL and/or the tectonic history of the study area. The Kii Peninsula and the southern coast of the Shikoku Island are located along the Nankai Trough where the Philippine Sea Plate is subducting under the Eurasian plate. There exist relatively well-preserved marine terraces along the coastal line with the elevation of ca. 50 -100 m. Because of this unique tectonic setting, the terraces are regarded as the suitable counterparts to reconstruct uplift history of the south coast of Japan. However, the ages of these terraces are poorly understood due to the lack of the ash layers that is suitable for the tephrochronology. In this study, we determine the age of the marine terraces using terrestrial in-situ cosmogenic radionuclides (TCN), 10Be and <span class="hlt">26</span><span class="hlt">Al</span>. This is the first age estimation of the marine terraces in Japan using TCN, allowing us to determine the uplift rates and the seismic history of the region.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015NIMPB.361..685S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015NIMPB.361..685S"><span>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://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sekimoto, S.; Okumura, S.; Yashima, H.; Matsushi, Y.; Matsuzaki, H.; Matsumura, H.; Toyoda, A.; Oishi, K.; Matsuda, N.; Kasugai, Y.; Sakamoto, Y.; Nakashima, H.; Boehnlein, D.; Coleman, R.; Lauten, G.; Leveling, A.; Mokhov, N.; Ramberg, E.; Soha, A.; Vaziri, K.; Ninomiya, K.; Omoto, T.; Shima, T.; Takahashi, N.; Shinohara, A.; Caffee, M. W.; Welten, K. C.; Nishiizumi, K.; Shibata, S.; Ohtsuki, T.</p> <p>2015-10-01</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 as 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>. The difference between these production cross sections may depend on the impact parameter (nuclear radius) and/or the target nucleus stiffness.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1235049-measurements-production-cross-sections-gev-mev-proton-bombardment-natcu-targets','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1235049-measurements-production-cross-sections-gev-mev-proton-bombardment-natcu-targets"><span>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.; ...</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>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/abs/2015EGUGA..17.2925F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.2925F"><span>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/2016GeCoA.189...70K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeCoA.189...70K"><span>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://adsabs.harvard.edu/abs/2017GeCoA.201....6P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017GeCoA.201....6P"><span>Calcium-aluminum-rich inclusions with fractionation and unidentified nuclear effects (FUN CAIs): II. Heterogeneities of magnesium isotopes and <span class="hlt">26</span><span class="hlt">Al</span> in the early Solar System inferred from in situ high-precision magnesium-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>Park, Changkun; Nagashima, Kazuhide; Krot, Alexander N.; Huss, Gary R.; Davis, Andrew M.; Bizzarro, Martin</p> <p>2017-03-01</p> <p>Calcium-aluminum-rich inclusions with isotopic mass fractionation effects and unidentified nuclear isotopic anomalies (FUN CAIs) have been studied for more than 40 years, but their origins remain enigmatic. Here we report in situ high precision measurements of aluminum-magnesium isotope systematics of FUN CAIs by secondary ion mass spectrometry (SIMS). Individual minerals were analyzed in six FUN CAIs from the oxidized CV3 carbonaceous chondrites Axtell (compact Type A CAI Axtell 2271) and Allende (Type B CAIs C1 and EK1-4-1, and forsterite-bearing Type B CAIs BG82DH8, CG-14, and TE). Most of these CAIs show evidence for excess 26Mg due to the decay of <span class="hlt">26</span><span class="hlt">Al</span>. The inferred initial <span class="hlt">26</span><span class="hlt">Al</span>/27Al ratios [(<span class="hlt">26</span><span class="hlt">Al</span>/27Al)0] and the initial magnesium isotopic compositions (δ26Mg0) calculated using an exponential law with an exponent β of 0.5128 are (3.1 ± 1.6) × 10-6 and 0.60 ± 0.10‰ (Axtell 2271), (3.7 ± 1.5) × 10-6 and -0.20 ± 0.05‰ (BG82DH8), (2.2 ± 1.1) × 10-6 and -0.18 ± 0.05‰ (C1), (2.3 ± 2.4) × 10-5 and -2.23 ± 0.37‰ (EK1-4-1), (1.5 ± 1.1) × 10-5 and -0.42 ± 0.08‰ (CG-14), and (5.3 ± 0.9) × 10-5 and -0.05 ± 0.08‰ (TE) with 2σ uncertainties. We infer that FUN CAIs recorded heterogeneities of magnesium isotopes and <span class="hlt">26</span><span class="hlt">Al</span> in the CAI-forming region(s). Comparison of <span class="hlt">26</span><span class="hlt">Al</span>-26Mg systematics, stable isotope (oxygen, magnesium, calcium, and titanium) and trace element studies of FUN and non-FUN igneous CAIs indicates that there is a continuum among these CAI types. Based on these observations and evaporation experiments on CAI-like melts, we propose a generic scenario for the origin of igneous (FUN and non-FUN) CAIs: (i) condensation of isotopically normal solids in an 16O-rich gas of approximately solar composition; (ii) formation of CAI precursors by aggregation of these solids together with variable abundances of isotopically anomalous grains-possible carriers of unidentified nuclear (UN) effects; and (iii) melt evaporation of these precursors</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>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://adsabs.harvard.edu/abs/2014M%26PS...49.1365O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014M%26PS...49.1365O"><span>Cosmic ray exposure and pre-atmospheric size of the Gebel Kamil iron meteorite</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ott, U.; Merchel, S.; Herrmann, S.; Pavetich, S.; Rugel, G.; Faestermann, T.; Fimiani, L.; Gomez-Guzman, J. M.; Hain, K.; Korschinek, G.; Ludwig, P.; D'Orazio, M.; Folco, L.</p> <p>2014-08-01</p> <p>Cosmogenic He, Ne, and Ar as well as the radionuclides 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>, 53Mn, and 60Fe have been determined on samples from the Gebel Kamil ungrouped Ni-rich iron meteorite by noble gas mass spectrometry and accelerator mass spectrometry (AMS), respectively. The meteorite is associated with the Kamil crater in southern Egypt, which is about 45 m in diameter. Samples originate from an individual large fragment ("Individual") as well as from shrapnel. Concentrations of all cosmogenic nuclides—stable and radioactive—are lower by a factor 3-4 in the shrapnel samples than in the Individual. Assuming negligible <span class="hlt">36</span><span class="hlt">Cl</span> decay during terrestrial residence (indicated by the young crater age <5000 years; Folco et al.), data are consistent with a simple exposure history and a <span class="hlt">36</span><span class="hlt">Cl</span>-36Ar cosmic ray exposure age (CRE) of approximately (366 ± 18) Ma (systematic errors not included). Both noble gases and radionuclides point to a pre-atmospheric radius >85 cm, i.e., a pre-atmospheric mass >20 tons, with a preferred radius of 115-120 cm (50-60 tons). The analyzed samples came from a depth of approximately 20 cm (Individual) and approximately 50-80 cm (shrapnel). The size of the Gebel Kamil meteoroid determined in this work is close to estimates based on impact cratering models combined with expectations for ablation during passage through the atmosphere (Folco et al).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017NIMPB.391...57K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017NIMPB.391...57K"><span>Progress report of the innovated KIST ion beam facility</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kim, Joonkon; Eliades, John A.; Yu, Byung-Yong; Lim, Weon Cheol; Chae, Keun Hwa; Song, Jonghan</p> <p>2017-01-01</p> <p>The Korea Institute of Science and Technology (KIST, Seoul, Republic of (S.) Korea) ion beam facility consists of three electrostatic accelerators: a 400 kV single ended ion implanter, a 2 MV tandem accelerator system and a 6 MV tandem accelerator system. The 400 kV and 6 MV systems were purchased from High Voltage Engineering Europa (HVEE, Netherlands) and commissioned in 2013, while the 2 MV system was purchased from National Electrostatics Corporation (NEC, USA) in 1995. These systems are used to provide traditional ion beam analysis (IBA), isotope ratio analysis (ex. accelerator mass spectrometry, AMS), and ion implantation/irradiation for domestic industrial and academic users. The main facility is the 6 MV HVEE Tandetron system that has an AMS line currently used for 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 analyses, and three lines for IBA that are under construction. Here, these systems are introduced with their specifications and initial performance results.</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>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>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('https://www.ncbi.nlm.nih.gov/pubmed/15706618','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15706618"><span>Neuroscience and 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>Palmblad, Magnus; Buchholz, Bruce A; Hillegonds, Darren J; Vogel, John S</p> <p>2005-02-01</p> <p>Accelerator mass spectrometry (AMS) is a mass spectrometric method for quantifying rare isotopes. It has had a great impact in geochronology and archaeology and is now being applied in biomedicine. AMS measures radioisotopes such as 3H, 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>, with zepto- or attomole sensitivity and high precision and throughput, allowing safe human pharmacokinetic studies involving microgram doses, agents having low bioavailability or toxicology studies where administered doses must be kept low (<1 microg kg(-1)). 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 time-scale of decades. We review here how AMS is applied in neurotoxicology and neuroscience.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRA..122.1473L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRA..122.1473L"><span>Simulation of the production rates of cosmogenic nuclides on the Moon based on Geant4</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Li, Yong; Zhang, Xiaoping; Dong, Wudong; Ren, Zhongzhou; Dong, Tiekuang; Xu, Aoao</p> <p>2017-02-01</p> <p>A numerical simulation model is built to simulate the production of cosmogenic nuclides based on Geant4 (GEometry ANd Tracking). Some modifications have been made for cross sections in Geant4 using the experimental data or the other proper model and the contributions of all secondary particles caused by cosmic rays are included in our simulation model. Our simulation results suggest a substantial contribution of the secondary charged pions to the production rates of 10Be and 14C, as high as 21.04% for 10Be and 21.36% for 14C, respectively. Within one set of self-consistent parameters, the simulation results of the production rates of the cosmogenic nuclides, 53Mn, <span class="hlt">36</span><span class="hlt">Cl</span>, <span class="hlt">41</span><span class="hlt">Ca</span>, <span class="hlt">26</span><span class="hlt">Al</span>, 10Be, and 14C, agree well with the measured data from Apollo 15 drill core. This model provides users a validated approach to study the production of cosmogenic nuclides on the planet surface and in the meteorites.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25844193','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25844193"><span>Synthèse et structure cristalline d'un matériau noir AgMn(II) 3(Mn(III) 0,<span class="hlt">26</span><span class="hlt">Al</span>0,74)(MoO4)5.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bouzidi, Chahira; Frigui, Wafa; Zid, Mohamed Faouzi</p> <p>2015-03-01</p> <p>A new silver aluminium trimangan-ese penta-molybdate {silver(I) trimanganese(II) aluminium penta-kis-[tetra-oxidomolybdate(VI)]}, AgMn(II) 3(Mn(III) 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 tetra-hedra 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 Mn(III) and Al(III) atoms share the same site, M. AgMn(II) 3(Mn(III) 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 tetra-mers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4350738','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4350738"><span>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/2007PhDT.........8D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007PhDT.........8D"><span>Neutron induced reactions on aluminum-26, chloride-36 and calcium-41 and their astrophysical implications</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>de Smet, Liesbeth Paula</p> <p></p> <p>In this work (n,p) and (n,a) reactions on 26 A1, <span class="hlt">36</span> <span class="hlt">Cl</span> and <span class="hlt">41</span> <span class="hlt">Ca</span> are studied as a function of the neutron energy. The measurements were performed at the high resolution GELINA time-of-flight facility of the IRMM in Geel, Belgium. Besides the nuclear physics information obtained from the resonance analysis of the reaction cross sections, these reactions are of importance in the understanding of the observed 36 S and <span class="hlt">26</span> <span class="hlt">Al</span> solar abundances. In the case of <span class="hlt">26</span> <span class="hlt">Al</span>, the 26 A1(n,a) 23 Na cross section up to 45 keV has been determined. Six resonances are observed. For three of them, the total level width and the spin could be calculated. For most of the resonances the obtained resonance parameters are in agreement with previous data. The calculated Maxwellian Averaged Cross Section values (MACS) used in stellar model calculations confirm that <span class="hlt">26</span> <span class="hlt">Al</span> is indeed severely depleted by neutron captures in AGB stars. In the (n,p) and (n,a) measurements on <span class="hlt">36</span> <span class="hlt">Cl</span>, eighteen resonances are observed in the energy region up to 250 keV, whereas eight were identified before. Only the lowest energy resonance shows a significant (n,(x)-contribution of (76±7)%, which is in perfect agreement with the value reported before. Furthermore, for four resonances, the resonance strength, spin, total and partial width G p could be determined. They are in good agreement with previous data, but the achieved accuracy is better. The calculated MACS values are used in stellar model calculations to trace the origin of 36 S and reveal that the weak component of the s-process occurring in massive stars accounts for almost the entire production of solar 36 S. The <span class="hlt">41</span> <span class="hlt">Ca</span>(n,a) 3 8Ar measurement is the first ever reported in the resonance region and affects the 36 S abundance through <span class="hlt">41</span> <span class="hlt">Ca</span>(n,a) 38 Ar(n,g) 39 Ar(n,a) 36 S. Twelve resonances are observed in the energy region up to 45 keV. For most of them the area, the total width, the spin and a value for G n /G p could be determined. After extension of the energy</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('http://adsabs.harvard.edu/abs/2011GeCoA..75.4752W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011GeCoA..75.4752W"><span>Extremely Na- and Cl-rich chondrule from the CV3 carbonaceous chondrite Allende</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wasserburg, G. J.; Hutcheon, I. D.; Aléon, J.; Ramon, E. C.; Krot, A. N.; Nagashima, K.; Brearley, A. J.</p> <p>2011-09-01</p> <p>We report on a study of Al3509, a large Na- and Cl-rich, radially-zoned object from the oxidized CV carbonaceous chondrite Allende. Al3509 consists of fine-grained ferroan olivine, ferroan Al-diopside, nepheline, sodalite, and andradite, and is crosscut by numerous veins of nepheline, sodalite, and ferroan Al-diopside. Some poorly-characterized phases of fine-grained material are also present; these phases contain no significant H 2O. The minerals listed above are commonly found in Allende CAIs and chondrules and are attributed to late-stage iron-alkali-halogen metasomatic alteration of primary high-temperature minerals. Textural observations indicate that Al3509 is an igneous object. However, no residual crystals that might be relicts of pre-existing CAI or chondrule minerals were identified. To establish the levels of <span class="hlt">26</span><span class="hlt">Al</span> and <span class="hlt">36</span><span class="hlt">Cl</span> originally present, <span class="hlt">26</span><span class="hlt">Al</span>- 26Mg and <span class="hlt">36</span><span class="hlt">Cl</span>- 36S isotopic systematics in sodalite were investigated. Al3509 shows no evidence of radiogenic 26Mg ∗, establishing an upper limit of the initial <span class="hlt">26</span><span class="hlt">Al</span>/ 27Al ratio of 3 × 10 -6. All sodalite grains measured show large but variable excesses of 36S, which, however, do not correlate with 35Cl/ 34S ratio. If these excesses are due to decay of <span class="hlt">36</span><span class="hlt">Cl</span>, local redistribution of radiogenic 36S ∗ after <span class="hlt">36</span><span class="hlt">Cl</span> had decayed is required. The oxygen-isotope pattern in Al3509 is the same as found in secondary minerals resulting from iron-alkali-halogen metasomatic alteration of Allende CAIs and chondrules and in melilite and anorthite of most CAIs in Allende. The oxygen-isotope data suggest that the secondary minerals precipitated from or equilibrated with a fluid of similar oxygen-isotope composition. These observations suggest that the formation of Al3509 and alteration products in CAIs and chondrules in Allende requires a very similar fluid phase, greatly enriched in volatiles (e.g., Na and Cl) and with Δ 17O ˜ -3‰. We infer that internal heating of planetesimals by <span class="hlt">26</span><span class="hlt">Al</span> would efficiently transfer</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22267765','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22267765"><span>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('https://www.ncbi.nlm.nih.gov/pubmed/22986053','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22986053"><span>Experimental (FT-IR and FT-RS) and theoretical (QC-DFT) studies of vibrational modes and molecular structure of new low-temperature phases of [Ru(NH3)6](BF4)3 and [Ru(NH3)6](ClO4)3.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Dołęga, Diana; Mikuli, Edward; Chruszcz-Lipska, Katarzyna</p> <p>2012-12-01</p> <p>Vibrational spectra of [Ru(NH(3))(6)](BF(4))(3) and [Ru(NH(3))(6)](ClO(4))(3) in their novel low-temperature solid phases were recorded using FT-IR and FT-RS. Quantum chemical calculations of molecular structure and vibrational modes were made separately for BF(4)(-),ClO(4)(-)and[Ru(NH(3))(6)](3+) ions. The harmonic vibrational frequencies and the related IR and RS bands intensities and activities, respectively, were simulated at the B3LYP/6-311+G(d) and B3LYP/LANL2TZ(f)/6-311+G(d,p) levels of the DFT. Full interpretation of the vibrational spectra has been carried out with the aid of the normal coordinate analysis. The assignments of the vibrational modes were based on the potential energy distribution data, using the MOLVIB program. The calculated Ru-N stretching frequencies are too low, in comparison to experiment, which indicates that B3LYP method underestimates the Ru-N bond strength. Some values of calculated and measured (obtained from X-ray) bond lengths and angles were also compared. Conclusions about possible interactions inside and between the complex ions were drawn.</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>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/2009PhDT........14B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009PhDT........14B"><span>Cosmogenic nuclides in early solar system materials</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bricker, Glynn Edward</p> <p>2009-09-01</p> <p>The overall goal of this research was to assess early solar system processes, particularly ancient proto-solar activity. This goal was addressed on two fronts. First, a model was developed to explain the provenance of now extinct radionuclides in early solar system materials, namely the refractory inclusions termed CAIs (Calcium-Aluminum-Inclusion) found in carbonaceous chondrites. As CAIs are believed to be the first solids to condense in the solar system and are also believed to have formed close to the proto-Sun, a model which explains the now extinct radionuclides found in CAIs constrains early solar system processes. Secondly, a series of measurements were performed on samples of the early solar system, namely chrondritic meteorites and the inclusions called chondrules, often contained within these meteorites. Chondrules, which are often a chief constituent of these meteorites, are believed to have originated close to the proto-Sun. As such, these materials should contain clues about solar processes at the beginning of the solar system. We propose a model for the incorporation of SLRs (short lived radionuclide) within CAIs in primitive carbonaceous meteorites. In this model SLRs are produced by energetic particle reactions in the proto-solar atmosphere of a more active proto-Sun characterized by proton fluxes higher than contemporary particle fluxes. These SLRs are entrained in the solar wind that is then implanted into CAI precursor material. This production mechanism is operational in the contemporary solar system and is responsible for implantation of 10 Be, 14 C and other nuclides in lunar materials. We utilize contemporary experimental solar wind production rates for 10Be and 14 C and theoretical ancient production rates for 7 Be, 10 Be, 14 C, <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 53 Mn. Using a ~ 10 5 enhancement in SEPs (solar energetic particles) and hence production rates in conjunction with an accepted refractory mass inflow rates close to the proto-Sun, we model</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1997M%26PS...32..413H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1997M%26PS...32..413H"><span>Complex exposure histories for meteorites with "short" 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>Herzog, G. F.; Vogt, S.; Albrecht, A.; Xue, S.; Fink, D.; Klein, J.; Middleton, R.; Weber, H. W.; Schultz, L.</p> <p>1997-05-01</p> <p>We report measurements of <span class="hlt">26</span><span class="hlt">Al</span> and 10Be activities in nine ordinary chondrites and of the light noble gas concentrations and <span class="hlt">36</span><span class="hlt">Cl</span> and <span class="hlt">41</span><span class="hlt">Ca</span> activities in subsets of those meteorites. All but Murray have low 21Ne concentrations (<1.0 (10-8 cm3 STP/g), and have previously been used to estimate 21Ne production rates. Ladder Creek, Murchison, Sena, and Timochin have inventories of cosmogenic radionuclides compatible with a single stage of irradiation and give 21Ne production rates consistent with the standard L-chondrite value of ~0.33 ( 10-8 cm3 STP/g-My. In contrast, Cullison, Guenie, Shaw, and Tsarev experienced complex irradiation histories. They and several other meteorites with low nominal exposure ages also have lower 3He/21Ne ratios than expected based on their 22Ne/21Ne ratios. A general association between low 21Ne contents and 3He losses suggests that meteorites with short lifetimes often occupy orbits with small perihelia. Meteorites with low 21Ne contents, one-stage exposure histories, and losses of cosmogenic 3He are rare, however. Possible explanations for the scarcity are 1) statistical; 2) that it is harder for more deeply buried proto-meteoroids to lose gas in a liberating collision; and 3) that it is harder to insert more deeply buried proto-meteoroids directly into orbits with small perihelia.</p> </li> <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>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://www.dtic.mil/docs/citations/ADA236222','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA236222"><span>SMM Observations of Interstellar <span class="hlt">26</span><span class="hlt">Al</span>: A Status Report</span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>1988-01-01</p> <p>provided direct evi- dence for the recent nucleosynthesis of intermediate-mass nuclei in the Galaxy. While modern nucleosynthesis theories suggest that... nucleosynthesis . While nucleosynthesis was originally considered to occur primarily in supernovae (Burbidge et al. 1957), modern theories suggest that...significant nucleosynthesis occurs in a variety 𔃻 6 6 064 of astrophysical objects, either through hydrostatic hydrogen or helium burning during the</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><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/2014NIMPB.329...22P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014NIMPB.329...22P"><span>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://hdl.handle.net/2060/19860022897','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19860022897"><span>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://www.ars.usda.gov/research/publications/publication/?seqNo115=209973','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=209973"><span>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://www.ars.usda.gov/research/publications/publication/?seqNo115=209261','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=209261"><span>The in vitro reduction of sodium [<span class="hlt">36</span><span class="hlt">Cl</span>]-chlorate in bovine ruminal fluid.</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>Sodium chlorate effectively reduces or eliminates the numbers of gram-negative pathogenic bacteria in the gastrointestinal tracts of live cattle. Limitations to the in vivo efficacy of chlorate are its rapid absorption from the gastrointestinal tract and its presumed reduction to chloride within the...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/publication/?seqNo115=209266','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=209266"><span>The in vitro reduction of sodium [<span class="hlt">36</span><span class="hlt">Cl</span>]-chlorate in bovine ruminal fluid</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>Sodium chlorate effectively reduces or eliminates the numbers of gram-negative pathogenic bacteria in the gastrointestinal tracts of live cattle. Limitations to the in vivo efficacy of chlorate are its rapid absorption from the gastrointestinal tract and its presumed reduction to chloride within the...</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>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>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://www.osti.gov/scitech/servlets/purl/5610250','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/5610250"><span>Progress in AMS measurements at the LLNL spectrometer. [Accelerator Mass Spectroscopy (AMS)</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Southon, J.R.; Vogel, J.S.; Trumbore, S.E.; Davis, J.C.; Roberts, M.L.; Caffee, M.; Finkel, R.; Proctor, I.D.; Heikkinen, D.W.; Berno, A.J.; Hornady, R.S.</p> <p>1991-06-01</p> <p>The AMS measurement program at LLNL began in earnest in late 1989, and has initially concentrated on {sup 14}C measurements for biomedical and geoscience applications. We have now begun measurements on {sup 10}Be and {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>, are presently testing the spectrometer performance for {sup <span class="hlt">26</span>}<span class="hlt">Al</span> and {sup 3}H, and will begin tests on {sup 7}Be, {sup <span class="hlt">41</span>}<span class="hlt">Ca</span> and {sup 129}I within the next few months. Our laboratory has a strong biomedical AMS program of {sup 14}C tracer measurements involving large numbers of samples (sometimes hundreds in a single experiment) at {sup 14}C concentrations which are typically .5--5 times Modern, but are occasionally highly enriched. The sample preparation techniques required for high throughput and low cross-contamination for this work are discussed elsewhere. Similar demands are placed on the AMS measurement system, and in particular on the ion source. Modifications to our GIC 846 ion source, described below, allow us to run biomedical and geoscience or archaeological samples in the same source wheel with no adverse effects. The source has a capacity for 60 samples (about 45 unknown) in a single wheel and provides currents of 30--60{mu}A of C{sup {minus}} from hydrogen-reduced graphite. These currents and sample capacity provide high throughput for both biomedical and other measurements: the AMS system can be started up, tuned, and a wheel of carbon samples measured to 1--1.5% in under a day; and 2 biomedical wheels can be measured per day without difficulty. We report on the present status of the Lawrence Livermore AMS spectrometer, including sample throughput and progress towards routine 1% measurement capability for {sup 14}C, first results on other isotopes, and experience with a multi-sample high intensity ion source. 5 refs.</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>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://www.osti.gov/scitech/servlets/purl/803429','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/803429"><span>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/2015AGUFMEP53B1025S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMEP53B1025S"><span>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> </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://adsabs.harvard.edu/abs/1993Metic..28R.429S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1993Metic..28R.429S"><span>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://adsabs.harvard.edu/abs/2017nuco.confb0305S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017nuco.confb0305S"><span>The <span class="hlt">26</span><span class="hlt">Al</span> Gamma-ray Line from Massive-Star Regions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Siegert, Thomas; Diehl, Roland</p> <p></p> <p>The measurement of gamma rays from the diffuse afterglow of radioactivity originating in massive-star nucleosynthesis is considered a laboratory for testing models, when specific stellar groups are investigated, at known distance and with well-constrained stellar population. Regions which have been exploited for such studies include Cygnus, Carina, Orion, and Scorpius-Centaurus. The Orion region hosts the Orion OB1 association and its subgroups at about 450 pc distance. We report the detection of l gamma rays from this region with INTEGRAL/SPI.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1997A%26A...321..452A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1997A%26A...321..452A"><span>Short-lived radionuclide production by non-exploding Wolf-Rayet 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.; Paulus, G.; Meynet, G.</p> <p>1997-05-01</p> <p>This paper presents an extension and update of previous calculations of the production by non-exploding Wolf-Rayet stars of radionuclides that could be responsible for certain isotopic anomalies discovered in meteoritic inclusions, or in meteoritic grains of probable circumstellar origin. Quantitative predictions of the time dependence of the radionuclide composition of the wind of Wolf-Rayet stars with initial masses in the wide 25<=M_i_<=120Msun_ range and for metallicities 0.001<=Z<=0.04 are obtained from a set of revised stellar evolution models. Special emphasis is put on the radionuclides with half-lives between about 10^5^ and 10^8^yr that could be produced by neutron captures during central helium burning and ejected during the WC-WO evolutionary phases. We stress that the radionuclide yield predictions are much more secure for Wolf-Rayet stars than for any other potential source of these species that has been contemplated up to now. This relates directly to the simplicity of these stars compared to highly difficult to model objects like Asymptotic Giant Branch stars, novae or supernovae. Our abundance predictions are confronted with existing observational data, or are hoped to help unravelling cases of potential interest for further laboratory quest when observations are lacking. The case of ^<span class="hlt">26</span>^<span class="hlt">Al</span>, of special interest for γ-ray line astronomy as well as for cosmochemistry, is also briefly revisited. In contrast to the other considered radionuclides, ^<span class="hlt">26</span>^<span class="hlt">Al</span> is produced during hydrogen burning, and is ejected at the WN evolutionary phase of the Wolf-Rayet stars. Our computed yields are also used as the basis for a qualitative discussion of the astrophysical plausibility of the contamination of the protosolar nebula with the radionuclides loading the Wolf-Rayet winds. Our calculations indicate that ^<span class="hlt">26</span>^<span class="hlt">Al</span>, ^<span class="hlt">41</span>^<span class="hlt">Ca</span> and ^107^Pd can be produced at a level compatible with the observations from a large variety of Wolf-Rayet stars with different masses and initial</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1990NIMPB..52..517F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1990NIMPB..52..517F"><span>Accelerator mass spectrometry in the biomedical sciences: applications in low-exposure biomedical and environmental dosimetry</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Felton, J. S.; Turteltaub, K. W.; Vogel, J. S.; Balhorn, R.; Gledhill, B. L.; Southon, J. R.; Caffee, M. W.; Finkel, R. C.; Nelson, D. E.; Proctor, I. D.; Davis, J. C.</p> <p>1990-12-01</p> <p>We are utilizing accelerator mass spectrometry as a sensitive detector for tracking the disposition of radioisotopically labeled molecules in the biomedical sciences. These applications have shown the effectiveness of AMS as a tool to quantify biologically important molecules at extremely low levels. For example, AMS is being used to determine the amount of carcinogen covalently bound to animal DNA (DNA adduct) at levels relevent to human exposure. Detection sensitivities are 1 carcinogen molecule bound in 1011 to 1012 DNA bases, depending on the specific activity of the radiolabeled carcinogen. Studies have been undertaken in our laboratory utilizing heterocyclic amine food-borne carcinogens and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), a potent environmental carcinogen, to study the metabolism of carcinogens at low doses. In addition, AMS is being used to detect the presence of rare proteins (mutant forms of protamine) in human sperm. Approximately l per 106 sperm analyzed contain the rare form of the protamine. Protamine isolated from this small number of cells is being analyzed by AMS, following 14C labeling. Thus, AMS can be used to verify the identity of an extremely small amount of biological material. Furthermore, an additional improvement of 2 orders of magnitude in the sensitivity of biomédical tracer studies is suggested by preliminary work with bacterial hosts depleted in radiocarbon. Other problems in the life sciences where detection sensitivity or sample sizes are limitations should also benefit from AMS. Studies are underway to measure the molecular targeting of cancer chemotherapeutics in human tissue and to pursue applications for receptor biology. We are also applying other candidate isotopes, such as 3H (double labeling with 14C) and <span class="hlt">41</span><span class="hlt">Ca</span> (bone absorption) to problems in biology. The detection of <span class="hlt">36</span><span class="hlt">Cl</span> and <span class="hlt">26</span><span class="hlt">Al</span> have applications for determination of human neutron exposure and understanding neurological toxicity, respectively. The results</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>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> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2000NIMPB.172..899J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000NIMPB.172..899J"><span>The PRIME Lab biomedical program</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.; Elmore, David; Rickey, Frank A.; Musameh, Sharif M.; Sharma, Pankaj; Hillegonds, Darren; Coury, Louis; Kissinger, Peter</p> <p>2000-10-01</p> <p>The biomedical accelerator mass spectrometry (AMS) initiative at PRIME Lab including the status of equipment and sample preparation is described. Several biomedical projects are underway involving one or more of the nuclides: 14C, <span class="hlt">26</span><span class="hlt">Al</span> and <span class="hlt">41</span><span class="hlt">Ca</span>. Routine production of CaF 2 and graphite is taking place. Finally, the future direction and plans for improvement of the biomedical program at PRIME Lab are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2000NIMPB.172...95L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000NIMPB.172...95L"><span>AMS at ANTARES - The first 10 years</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lawson, E. M.; Elliott, G.; Fallon, J.; Fink, D.; Hotchkis, M. A. C.; Hua, Q.; Jacobsen, G. E.; Lee, P.; Smith, A. M.; Tuniz, C.; Zoppi, U.</p> <p>2000-10-01</p> <p>The status and capabilities of the ANTARES AMS facility after 10 years are reviewed. The common AMS radioisotopes, 10Be, 14C, <span class="hlt">26</span><span class="hlt">Al</span>, <span class="hlt">36</span><span class="hlt">Cl</span> and 129I, are routinely analysed. A capability for the detection of 236U and other actinide isotopes has been developed. The measurement program includes support to Quaternary science projects at Australian universities and to ANSTO projects in global climate change and nuclear safeguards.</p> </li> <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>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://adsabs.harvard.edu/abs/2006M%26PS...41..375K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006M%26PS...41..375K"><span>Monte Carlo simulation of GCR neutron capture production of cosmogenic nuclides in stony meteorites and lunar surface</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>KolláR, D.; Michel, R.; Masarik, J.</p> <p>2006-03-01</p> <p>A purely physical model based on a Monte Carlo simulation of galactic cosmic ray (GCR) particle interaction with meteoroids is used to investigate neutron interactions down to thermal energies. Experimental and/or evaluated excitation functions are used to calculate neutron capture production rates as a function of the size of the meteoroid and the depth below its surface. Presented are the depth profiles of cosmogenic radionuclides <span class="hlt">36</span><span class="hlt">Cl</span>, <span class="hlt">41</span><span class="hlt">Ca</span>, 60Co, 59Ni, and 129I for meteoroid radii from 10 cm up to 500 cm and a 2π irradiation. Effects of bulk chemical composition on n-capture processes are studied and discussed for various chondritic and lunar compositions. The mean GCR particle flux over the last 300 ka was determined from the comparison of simulations with measured <span class="hlt">41</span><span class="hlt">Ca</span> activities in the Apollo 15 drill core. The determined value significantly differs from that obtained using equivalent models of spallation residue production.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/publication/?seqNo115=332989','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=332989"><span>Distribution, identification, and quantification of residues after treatment of ready-to-eat salami with <span class="hlt">36</span><span class="hlt">Cl</span>-labeled or nonlabeled chlorine dioxide gas</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>Chlorine dioxide gas actively eliminates a variety of food-borne pathogens and rot organisms, including Listeria monocytogenes on food and food preparation surfaces. However the disposition and fate of chlorine dioxide gas on ready-to-eat meat products has not been previously described. When ready-t...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/7132822','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/7132822"><span>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('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3337337','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3337337"><span>The sperm surface localization of the TRP-3/SPE-<span class="hlt">41</span> <span class="hlt">Ca</span>2+-permeable channel depends on SPE-38 function in Caenorhabditis elegans</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Singaravelu, Gunasekaran; Chatterjee, Indrani; Rahimi, Sina; Druzhinina, Marina K.; Kang, Lijun; Xu, X. Z. Shawn; Singson, Andrew</p> <p>2012-01-01</p> <p>Despite undergoing normal development and acquiring normal morphology and motility, mutations in spe-38 or trp-3/spe-41 cause identical phenotypes in Caenorhabditis elegans – mutant sperm fail to fertilize oocytes despite direct contact. SPE-38 is a novel, four-pass transmembrane protein and TRP-3/SPE-41 is a Ca2+-permeable channel. Localization of both of these proteins is confined to the membranous organelles (MOs) in undifferentiated spermatids. In mature spermatozoa, SPE-38 is localized to the pseudopod and TRP-3/SPE-41 is localized to the whole plasma membrane. Here we show that the dynamic redistribution of TRP-3/SPE-41 from MOs to the plasma membrane is dependent on SPE-38. In spe-38 mutant spermatozoa, TRP-3/SPE-41 is trapped within the MOs and fails to reach the cell surface despite MO fusion with the plasma membrane. Split-ubiquitin yeast-two-hybrid analyses revealed that the cell surface localization of TRP-3/SPE-41 is likely regulated by SPE-38 through a direct protein-protein interaction mechanism. We have identified sequences that influence the physical interaction between SPE-38 and TRP-3/SPE-41, and show that these sequences in SPE-38 are required for fertility in transgenic animals. Despite the mislocalization of TRP-3/SPE-41 in spe-38 mutant spermatozoa, ionomycin or thapsigargin induced influx of Ca2+ remains unperturbed. This work reveals a new paradigm for the regulated surface localization of a Ca2+-permeable channel. PMID:22425620</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19960054326&hterms=la&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dla','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19960054326&hterms=la&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dla"><span>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('https://www.osti.gov/scitech/biblio/308252','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/308252"><span>Protostellar Cosmic Rays and Extinct Radioactivities in Meteorites</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Lee, T.; Shu, F.H.; Shang, H.; Glassgold, A.E.; Rehm, K.E.</p> <p>1998-10-01</p> <p>Calcium-aluminum{endash}rich inclusions (CAIs) and chondrules of chondritic meteorites may originate with the melting of dustballs launched by a magnetically driven bipolar outflow from the inner edge of the primitive solar nebula. Bombardment by protostellar cosmic rays may make the rock precursors of CAIs and chondrules radioactive, producing radionuclides found in meteorites that are difficult to obtain with other mechanisms. Reasonable scalings from the observed hard X-rays for the cosmic-ray protons released by flares in young stellar objects yield the correct amounts of {sup <span class="hlt">41</span>}<span class="hlt">Ca</span>, {sup 53}Mn, and {sup 138}La inferred for meteorites, but proton- and {alpha}-induced transformations underproduce {sup <span class="hlt">26</span>}<span class="hlt">Al</span> by a factor of about 20. The missing {sup <span class="hlt">26</span>}<span class="hlt">Al</span> may be synthesized by {sup 3}He nuclei accelerated in impulsive flares reacting primarily with {sup 24}Mg, an abundant isotope in the target precursor rocks. The mechanism allows a simple explanation for the very different ratios of {sup <span class="hlt">26</span>}<span class="hlt">Al</span>/{sup 27}Al inferred for normal CAIs, CAIs with fractionated and unidentified nuclear (FUN) anomalies, and chondrules. The overproduction of {sup <span class="hlt">41</span>}<span class="hlt">Ca</span> by analogous {sup 3}He reactions and the case of {sup 60}Fe inferred for eucritic meteorites require special interpretations in this picture. {copyright} {ital {copyright} 1998.} {ital The American Astronomical Society}</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>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://www.osti.gov/scitech/servlets/purl/757462','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/757462"><span>Exposure History of Separated Phases from the Kapoeta Meteorite</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Caffee, M W; Nishiizumi, K; Mazarik, J</p> <p>2000-01-14</p> <p>The cosmogenic radionuclides, {sup 10}Be (1.5 Ma), {sup <span class="hlt">26</span>}<span class="hlt">Al</span> (0.705 Ma), {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> (0.301 Ma), and {sup 53}Mn (3.7 Ma) were measured in selected clasts and matrix samples from the howardite Kapoeta. This work is an extension of that based on {sup 10}Be and {sup <span class="hlt">26</span>}<span class="hlt">Al</span> [1]. Recent work based on measurements of cosmogenic {sup 21}Ne suggest the possibility of a complex recent exposure history for Kapoeta. The measurement of these radionuclides, in conjunction with production rates based on Monte Carlo calculations, can constrain exposure conditions and durations. Taken together, the radionuclide data are entirely consistent with a single stage 4{pi} exposure lasting {approximately} 3 Ma.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1992Metic..27Q.205B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1992Metic..27Q.205B"><span>Simulation of Galactic Cosmic Ray Interactions with Regolith: Implications for Cosmogenic Nuclide and Planetary Surface Studies</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bobias, S. G.; Dempsey, J. F.; Englert, P. A. J.; Drake, D. M.; Reedy, R. C.</p> <p>1992-07-01</p> <p>In planetary, asteroidal, and cometary surfaces the development of cosmic ray produced secondary particle cascades depends very much on the chemical composition. Most important is the abundance and distribution of neutron moderators, such as hydrogen and carbon. Their presence influences the distribution and flux of neutrons in extraterrestrial surfaces. Consequently, the distribution and activity of neutron produced cosmogenic nuclides, such as the neutron capture products ^<span class="hlt">36</span><span class="hlt">Cl</span> (3.01x10^5y), ^<span class="hlt">41</span><span class="hlt">Ca</span> (1.03x10^5y), ^59Ni (7.6x10^4 y) and ^60Co (5.271y), and the medium energy products such as ^22Na (2.605 y, from Al), ^<span class="hlt">26</span><span class="hlt">Al</span> (7.4x10^5 y, from Si), ^53Mn (3.7x10^6, from Fe), etc., will be dependent on the development of the secondary neutron fluxes. Three thick target bombardments of artificial planetary surface soil (martian) [1,2,3] that measured the secondary particle cascade as well as surface neutron flux and leakage spectra were performed at the Los Alamos Meson Physics Facility's Weapons Neutron Research Laboratory. They provide data to study qualitatively and quantitatively the relation between bombarding galactic cosmic ray particles, the development of neutrons inside a surface and of neutrons emitted from a planetary surface. Past thick target bombardments were limited to only determining the secondary particle cascades or the emitted gamma radiation [4,5,6]. The experiments show that the second target, which was two times larger than the target for the first experiment, was holding more neutrons inside the target. The third irradiation utilized a polyethylene sheet in front of the second target to simulate the presence of water or ice on a planetary surface. Threshold monitors were placed both along the axis of symmetry and radially displaced axes. The monitors included foils of Ti, Mn, Fe, Co, Ni, and Au. The induced radioactivity was measured at Los Alamos by conventional gamma-ray spectrometry approximately 48 hours at the end of irradiation. Both the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22370139','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22370139"><span>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('http://adsabs.harvard.edu/abs/2007E%26PSL.254..115U','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007E%26PSL.254..115U"><span>A FUN-like hibonite inclusion with a large 26Mg-excess</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ushikubo, Takayuki; Hiyagon, Hajime; Sugiura, Naoji</p> <p>2007-02-01</p> <p>We found a unique hibonite (CaAl12O19) inclusion Kz1-2 from the Kainsaz (CO3) chondrite, which exhibits evidence for a strong link between "normal" CAIs and FUN inclusions. Kz1-2 shows strongly fractionated isotopic compositions of O, Ca, and Ti preferring heavy isotopes and a characteristic REE abundance pattern similar to those of FUN (or HAL-type hibonite) inclusions, suggesting an intensive distillation process in the formation of this inclusion. Unlike FUN inclusions, however, Kz1-2 shows large excesses in 26Mg and possibly in 41K most likely from the decays of now-extinct nuclides <span class="hlt">26</span><span class="hlt">Al</span> and <span class="hlt">41</span><span class="hlt">Ca</span> with the inferred initial ratios of (<span class="hlt">26</span><span class="hlt">Al</span>/27Al)0 ∼ 5.3 × 10- 5 and (<span class="hlt">41</span><span class="hlt">Ca</span>/40Ca)0 ∼ 1.1 × 10- 8, respectively, and no detectable mass-independent isotopic anomalies in Ca and Ti, both of which are characteristic of "normal" CAIs. These observations suggest that the distillation process which produced isotopic fractionation in Kz1-2 occurred as early as the formation of "normal" CAIs. It is also inferred that the formation process of FUN inclusions is closely related to that of "normal" CAIs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22364021','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22364021"><span>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> </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/2014ApJ...781L..28L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014ApJ...781L..28L"><span>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>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=nuclear+AND+instruments&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=78096538&CFTOKEN=58883082','EPA-EIMS'); return false;" href="http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=67703&keyword=nuclear+AND+instruments&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=78096538&CFTOKEN=58883082"><span>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://adsabs.harvard.edu/abs/2017ApJ...836..126W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ApJ...836..126W"><span>Intermediate-mass Asymptotic Giant Branch Stars and Sources of <span class="hlt">26</span><span class="hlt">Al</span>, 60Fe, 107Pd, and 182Hf in the 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>Wasserburg, G. J.; Karakas, Amanda I.; Lugaro, Maria</p> <p>2017-02-01</p> <p>We explore the possibility that the short-lived radionuclides {}<span class="hlt">26</span>{{<span class="hlt">A}}l</span>, {}60{{F}}e, {}107{{P}}d, and {}182{{H}}f inferred to be present in the proto-solar cloud originated from 3–8 {M}ȯ asymptotic giant branch (AGB) stars. Models of AGB stars with initial mass above 5 {M}ȯ are prolific producers of {}<span class="hlt">26</span>{{<span class="hlt">A}}l</span> owing to hot bottom burning (HBB). In contrast, {}60{{F}}e, {}107{{P}}d, and {}182{{H}}f are produced by neutron captures: {}107{{P}}d and {}182{{H}}f in models ≲ 5 {M}ȯ , and {}60{{F}}e in models with higher mass. We mix stellar yields from solar-metallicity AGB models into a cloud of solar mass and composition to investigate whether it is possible to explain the abundances of the four radioactive nuclides at the Sun’s birth using one single value of the mixing ratio between the AGB yields and the initial cloud material. We find that AGB stars that experience efficient HBB (≥slant 6 {M}ȯ ) cannot provide a solution because they produce too little {}182{{H}}f and {}107{{P}}d relative to {}<span class="hlt">26</span>{{<span class="hlt">A}}l</span> and {}60{{F}}e. Lower-mass AGB stars cannot provide a solution because they produce too little {}<span class="hlt">26</span>{{<span class="hlt">A}}l</span> relative to {}107{{P}}d and {}182{{H}}f. A self-consistent solution may be found for AGB stars with masses in between (4–5.5 {M}ȯ ), provided that HBB is stronger than in our models and the {}13{{C}}(α, n){}16{{O}} neutron source is mildly activated. If stars of {{M}}< 5.5 {M}ȯ are the source of the radioactive nuclides, then some basis for their existence in proto-solar clouds needs to be explored, given that the stellar lifetimes are longer than the molecular cloud lifetimes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017Geomo.278...60C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017Geomo.278...60C"><span>Cirques have growth spurts during deglacial and interglacial periods: Evidence from 10Be and <span class="hlt">26</span><span class="hlt">Al</span> nuclide inventories in the central and eastern Pyrenees</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Crest, Y.; Delmas, M.; Braucher, R.; Gunnell, Y.; Calvet, M.</p> <p>2017-02-01</p> <p>Cirques are emblematic landforms of alpine landscapes. The statistical distribution of cirque-floor elevations is used to infer glacial equilibrium-line altitude, and the age of their frontal moraines for reconstructing glacial chronologies. Very few studies, however, have sought to measure cirque-floor and supraglacial ridgetop bedrock downwearing rates in order to confront these denudation estimates with theoretical models of Quaternary mountain landscape evolution. Here we use 10Be nuclide samples (n = 36) from moraines, bedrock steps, and supraglacial ridgetops among a population of cirques in the east-central Pyrenees in order to quantify denudation in the landscape and detect whether the mountain topography bears any relevance to the glacial buzzsaw hypothesis. Minimum exposure ages (MEAs) obtained for a succession of moraines spanning the Oldest Dryas to the Holocene produced a deglaciation chronology for three different Pyrenean ranges: Maladeta, Bassiès, and Carlit. Based on a series of corrections, calibrations, and chronostratigraphic tuning procedures, MEAs on ice-polished bedrock exposures were further used to model denudation depths at nested timescales during the Würm, the Younger Dryas, and the Holocene. Results show that subglacial cirque-floor denudation was lower during glacial periods (Würm: 10 mm/ka) than during deglacial and interglacial periods (tens to hundreds of mm/ka). The relative inefficiency of glacial denudation in the cirque zone during the Würm would have resulted from (i) cold-based and/or (ii) low-gradient glaciers situated in the upper reaches of the icefield; and/or from (iii) glacier-load starvation because of arrested clast supply from supraglacial rockslopes situated in the permafrost zone. Denudation peaked during the Younger Dryas and Holocene glacial advances, a time when cirque glaciers became steeper, warmer-based, and when frost cracking weakened supraglacial ridgetops, thus enhancing subglacial erosion by providing debris to the sliding glacier base. Cirques, therefore, grow faster during more temperate periods of cirque glaciation than under full glacial conditions. Another key finding was the very low rates of ridgetop lowering averaged over the Würm and Holocene (10-25 mm/ka). A comparison of the denudation rates obtained from the cirque zone with regional estimates of crustal uplift indicates that the alpine topography is not in a steady state. The low intensity of glacial denudation failed to bring the topography to a buzzsaw equilibrium state.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002APS..DNP.GF009C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002APS..DNP.GF009C"><span>The Search for Supernovae 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.; Thompson, L. G.; Davis, M. E.; Davis, A. M.; Lewis, R. S.</p> <p>2002-10-01</p> <p>It has been proposed 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, type II supernova [1]. A simple model is developed and calculations are presented to estimate the number of grains with ^<span class="hlt">26</span><span class="hlt">Al</span> enhancements that could be deposited per cm^2 on the Earth by a type II supernova. We describe the search for supernova grains that may possess ^<span class="hlt">26</span><span class="hlt">Al</span> enhancements amongst grains filtered from the 308.5m Guliya ice core recovered from the Qinghai-Tibetan plateau in China [2]. We have obtained Guliya grain samples from the epochs corresponding to previously discovered ^10Be and ^<span class="hlt">36</span><span class="hlt">Cl</span> enhancements at 35ky and 60ky as well as ˜1-4ky samples surrounding the time periods 25ky, 55ky, 68ky. Additionally, we obtained a sample that spans the time period 2-10ky. The process of identifying potential supernova grains amongst their terrestrial cousins employs a procedure developed at the University of Chicago for detecting interstellar grains in meteoritic samples [3]. We report the identification of the potential supernova grains, CaAl_12O_19, Al_2O_3, and MgAl_2O4 in the samples. This work is supported in part by National Science Foundation grant PHY-9901241. [1] Ellis, J., Fields, B. D., Schramm, D. N. Astrophys. J., 470: 1227, 1996. [2] Thompson, L. G. et al. Science, 276: 1821, 1997. [3] Amari, S., Lewis, R.S., Anders, E. Geochim. Cosmochim. Acta, 58: 459, 1994.</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>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://adsabs.harvard.edu/abs/1994NIMPB..92..445V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1994NIMPB..92..445V"><span>Accelerator mass spectrometry in biomedical research</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vogel, J. S.; Turteltaub, K. W.</p> <p>1994-06-01</p> <p>Biological effects occur in natural systems at chemical concentrations of parts per billion (1:10 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 13-15 on milligram-sized samples and is ideal for quantifying long-lived radioisotopic labels for tracing biochemical pathways in natural systems. 14C-AMS has now been coupled to a variety of organic separation and definition technologies. Our primary research investigates pharmacokinetics and genotoxicities of toxins and drugs at very low doses. Human subjects research using AMS includes nutrition, toxicity and elemental balance studies. 3H, <span class="hlt">41</span><span class="hlt">Ca</span> and <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://adsabs.harvard.edu/abs/2000NIMPB.172..856C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000NIMPB.172..856C"><span>Sample processing for earth science studies at ANTARES</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Child, D.; Elliott, G.; Mifsud, C.; Smith, A. M.; Fink, D.</p> <p>2000-10-01</p> <p>AMS studies in earth sciences at ANTARES, ANSTO created a need for the processing of mineral and ice samples for 10Be, <span class="hlt">26</span><span class="hlt">Al</span> and <span class="hlt">36</span><span class="hlt">Cl</span> target preparation. Published procedures have been adapted to our requirements and improved upon where necessary. In particular, new methods to isolate Be with reproducible, high recoveries in the presence of excess Al and Ti were achieved. An existing elution scheme for a cation exchange column procedure was modified to incorporate the use of a 0.25 M H2SO4+0.015% H 2O2 washing step to elute the Ti peroxide complex formed. Problems with dust contamination in ice contributing to measured 10Be signals are also addressed and a procedure developed for its removal.</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>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> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22126771','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22126771"><span>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('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>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('https://www.osti.gov/scitech/biblio/21513434','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21513434"><span>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/6392768','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/6392768"><span>Accelerator mass spectrometry and radioisotope detection at the Argonne FN tandem facility</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Henning, W.; Kutschera, W.; Paul, M.; Smither, R.K.; Stephenson, E.J.; Yntema, J.L.</p> <p>1980-01-01</p> <p>The Argonne FN tandem accelerator and standard components of its experimental heavy-ion research facility, have been used as a highly-sensitive mass spectrometer to detect several long-lived radioisotopes and measure their concentration by counting of accelerated ions. Background beams from isobaric nuclei have been eliminated by combining the dispersion from the energy loss in a uniform Al foil stack with the momentum resolution of an Enge split-pole magnetic spectrograph. Radioisotope concentrations in the following ranges have been measured: /sup 14/C//sup 12/C = 10/sup -12/ to 10/sup -13/, /sup <span class="hlt">26</span>/<span class="hlt">Al</span>//sup 27/Al = 10/sup -10/ to 10/sup -12/, /sup 32/Si/Si = 10/sup -8/ to 10/sup -14/, /sup <span class="hlt">36</span>/<span class="hlt">Cl</span>/Cl = 10/sup -10/ to 10/sup -11/. Particular emphasis was put on exploring to what extent the technique of identifying and counting individual ions in an accelerator beam can be conveniently used to determine nuclear quantities of interest when their measurement involves very low radioisotope concentrations. The usefulness of this method can be demonstrated by measuring the /sup 26/Mg(p,n)/sup <span class="hlt">26</span>/<span class="hlt">Al</span>(7.2 x 10/sup 5/ yr) cross section at proton energies in the astrophysically interesting range just above threshold, and by determining the previously poorly known half life of /sup 32/Si.</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>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('https://www.ncbi.nlm.nih.gov/pubmed/10828298','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/10828298"><span>Bioanalytical applications of accelerator mass spectrometry for pharmaceutical research.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Turteltaub, K W; Vogel, J S</p> <p>2000-07-01</p> <p>Accelerator mass spectrometry (AMS) is a mass spectrometric method for quantifying isotopes. It has had great impact in the geosciences and is now being applied in the biomedical fields. AMS measures radioisotopes such as 14C, 3H, <span class="hlt">41</span><span class="hlt">Ca</span>, and <span class="hlt">36</span><span class="hlt">Cl</span>, and others, with attomole sensitivity and high precision. Its use is allowing absorption, distribution, metabolism and elimination studies, as well as detailed pharmacokinetics, to be carried out directly in humans with very low chemical or radiological hazard. It is used in combination with standard separation methodologies, such as chromatography, in identification of metabolites and molecular targets for both toxicants and pharmacologic agents. AMS allows the use of very low specific activity chemicals (< 1 mCi/mmol), creating opportunities to use compounds not available in a high specific activity form, such as those that must be biosynthesized, produced in combinatorial libraries, or made through inefficient synthesis. AMS is allowing studies to be carried out with agents having low bioavailability, low systemic distributions, or high toxicity where administered doses must be kept low (<1 microg/kg). It may have uses in tests for idiosyncratic metabolism, drug interaction, or individual susceptibility, among others. The ability to use very low chemical doses, low radiological doses, small samples and conduct multiple dose studies may help move drug candidates into humans faster and safer than before. The uses of AMS are growing and its potential for drug development is only now beginning to be realized.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JPCS..101...34H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JPCS..101...34H"><span>Dynamics of NH3 ligands and ClO4- anions in the phase transition in [Cd(NH3)6](ClO4)2 studied by x-ray powder diffraction, neutron scattering methods and infrared spectroscopy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hetmańczyk, Łukasz; Hetmańczyk, Joanna</p> <p>2017-02-01</p> <p>Phase transition, reorientational dynamics of NH3 ligands and ClO4- anions and crystal structure changes were investigated using x-ray powder diffraction (XRPD), neutron powder diffraction (NPD), quasi-elastic neutron scattering (QENS) and Fourier transform infrared spectroscopy (FT-IR). Most measurements were carried out in the temperature range 9-300 K. The diffraction techniques revealed that NH3 ligands and ClO4- anions are orientationally disordered at room temperature. During the cooling process, the high temperature cubic phase transforms into a lower symmetry phase (most probably of monoclinic structure). The QENS results confirm that NH3 ligands perform picoseconds reorientational motions both in the high and low temperature phases. This motion is almost unaffected by the observed phase transition (Tc=138.9 K on heating) and can be well described assuming the three fold jump model. On the other hand, the band shape analysis performed for the IR band connected with ClO4- internal vibration mode δd(OClO)E at 461 cm-1 clearly shows that ClO4- anions reorientate quickly in the high temperature phase, but that motion begins slowing down in the vicinity of the phase transition. Below 150 K the exponential reorientation relaxation term vanishes and only the vibrational relaxation term is present; small discontinuity is also visible. Moreover, below the phase transition temperature Tc splitting of the infrared absorption bands connected with some NH3 internal vibrations is observed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002M%26PS...37.1711H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002M%26PS...37.1711H"><span>Cosmogenic nuclides in the Brenham pallasite</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Honda, M.; Caffee, M. W.; Miura, Y. N.; Nagai, H.; Nagao, K.; Nishiizumi, K.</p> <p>2002-12-01</p> <p>Cosmic-ray-produced (cosmogenic) nuclides were studied in fragments of the Brenham pallasite, a large stony iron meteorite. The contents of light noble gases (He, Ne, and Ar) and long-lived radionuclides (10Be, <span class="hlt">26</span><span class="hlt">Al</span>, <span class="hlt">36</span><span class="hlt">Cl</span>, and 53Mn), produced by nuclear reactions with cosmic rays, were measured in the separated metal and olivine phases from numerous samples representing a wide range of shielding conditions in the meteoroid. The distribution of cosmogenic nuclide concentrations in the metal follows patterns similar to that observed in large iron meteorites. Shielding effects were estimated from the relative proportions of low- and high-energy reaction products. The production rates varied, from surface to interior, by a factor of more than several hundred. The <span class="hlt">36</span><span class="hlt">Cl</span>-36Ar cosmic-ray exposure age of Brenham is 156 +/- 8 Myr. This determination is based on a multiple nuclide approach that utilizes cosmogenic nuclide pairs. This approach not only yields a "shielding independent" exposure age but also demonstrates that the production of cosmogenic nuclides occurred in a single stage. The depth profiles of 10Be in the stone phase and 53Mn in the metal phase are shown superimposed on corresponding profiles from the Apollo 15 long drill core. Surprisingly low abundances of lithophile elements, such as K, U, and Th, provided a unique opportunity to examine the production systematics of those nuclides whose inventories typically have significant contributions from non-cosmogenic sources, particularly radiogenic contributions. The U and Th contents of the olivine samples are extremely low, allowing detection of cosmogenic 4He production from oxygen, magnesium, silicon, and iron.</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>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('http://adsabs.harvard.edu/abs/2013GeCoA.113..193J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013GeCoA.113..193J"><span>Multi-element isotopic analyses of presolar graphite grains from Orgueil</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jadhav, Manavi; Zinner, Ernst; Amari, Sachiko; Maruoka, Teruyuki; Marhas, Kuljeet K.; Gallino, Roberto</p> <p>2013-07-01</p> <p>We report C, N, O, Si, Al-Mg, K, Ca, and Ti isotopic analyses of presolar graphite grains from the Orgueil CI chondrite. NanoSIMS isotopic measurements were made on 345 grains from seven density fractions, with grain sizes >1 μm: low-density grains from OR1b, OR1c, and OR1d; and high-density grains from OR1f, OR1g, OR1h, and OR1i. In all fractions, except OR1b and OR1h, we found presolar graphite as demonstrated by the large range of 12C/13C ratios (4-2480) measured in individual grains. Some isotopic properties are dependent on density: low-density grains contain 18O, 15N, and 28Si excesses, while the majority of high-density grains contain normal N and O, and are generally enriched in 29Si and 30Si. The 15N, 18O, and 28Si excesses and very high derived isotopic ratios for the extinct radionuclides <span class="hlt">26</span><span class="hlt">Al</span>, <span class="hlt">41</span><span class="hlt">Ca</span>, and 44Ti in low-density grains indicate an origin from supernovae. In order to explain the isotopic ratios measured in these grains, we present mixing scenarios between different layers of supernovae and discuss the limitations of various theoretical models. Silicon-30 and 12C excesses in high-density grains and lower values for short-lived radionuclides (<span class="hlt">26</span><span class="hlt">Al</span> and <span class="hlt">41</span><span class="hlt">Ca</span>) indicate an origin in asymptotic giant branch stars with low metallicities. Some supernova grains, with 44Ca excesses, are also present amongst the high-density grains. Grains with low 12C/13C ratios (without evidence for 44Ti) and large excesses in 42,43Ca and 46,47,49,50Ti probably originate from post-asymptotic giant branch stars, that have suffered a very late thermal pulse, and can achieve low 12C/13C ratios and large neutron capture signatures in Ca and Ti isotopes. We conclude that most low-density graphite grains originate from supernovae while high-density graphite grains have multiple stellar sources: low-metallicity and born-again asymptotic giant branch stars, Type II supernovae, and possibly, J-type stars.</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('https://www.ncbi.nlm.nih.gov/pubmed/22106251','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22106251"><span>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('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>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('http://adsabs.harvard.edu/abs/2001M%26PS...36.1547L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001M%26PS...36.1547L"><span>The production of cosmogenic nuclides by GCR-particles for 2 pi exposure geometries</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.; Neumann, S.; Wieler, R.; Michel, R.</p> <p>2001-11-01</p> <p>We present a purely physical model for the calculation of depth dependent production rates in 2 pi exposure geometries by galactic cosmic rays (GCR). Besides the spectra of primary and secondary particles and the excitation functions of the underlying nuclear reactions, the model is based on the integral number of GCR particles in the lunar orbit. We derived this value from adjusting modeled depth profiles for 10Be, <span class="hlt">26</span><span class="hlt">Al</span>, and 53Mn to measured data from the Apollo 15 drill core. The J0,GCR-value of 4.54 cm-2 s-1 and the solar modulation parameter of M = 490 MeV determined this way for 1 AU is in reasonable agreement with the J0,GCR-value derived recently for the meteoroid orbits (Leya et al., 2000b). We also show that the mean GCR proton spectrum in the lunar orbit has not changed substantially over about the last 10 Myr. For the major target elements we present depth dependent production rates for 10Be, 14C, <span class="hlt">26</span><span class="hlt">Al</span>, <span class="hlt">36</span><span class="hlt">Cl</span> and 53Mn, as well as for the rare gas isotopes 20,21,22Ne. In addition we present production rates for 36,38Ar from Fe and Ni. The new results are consistent with the data for stony meteoroids presented recently by our group (Leya et al., 2000b), but for the rare gas isotopes the new production rates sometimes differ significantly from earlier estimates. The applicability of the 22Ne/21Ne ratio as a shielding parameter is also discussed.</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>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>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/1987Sci...236..543E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1987Sci...236..543E"><span>Accelerator Mass Spectrometry for Measurement of Long-Lived Radioisotopes</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; Phillips, Fred M.</p> <p>1987-05-01</p> <p>Particle accelerators, such as those built for research in nuclear physics, can also be used together with magnetic and electrostatic mass analyzers to measure rare isotopes at very low abundance ratios. All molecular ions can be eliminated when accelerated to energies of millions of electron volts. Some atomic isobars can be eliminated with the use of negative ions; others can be separated at high energies by measuring their rate of energy loss in a detector. The long-lived radioisotopes 10Be, 14C, <span class="hlt">26</span><span class="hlt">Al</span>, <span class="hlt">36</span><span class="hlt">Cl</span>, and 129I can now be measured in small natural samples having isotopic abundances in the range 10-12 to 10-15 and as few as 105 atoms. In the past few years, research applications of accelerator mass spectrometry have been concentrated in the earth sciences (climatology, cosmochemistry, environmental chemistry, geochronology, glaciology, hydrology, igneous petrogenesis, minerals exploration, sedimentology, and volcanology), in anthropology and archeology (radiocarbon dating), and in physics (searches for exotic particles and measurement of half-lives). In addition, accelerator mass spectrometry may become an important tool for the materials and biological sciences.</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>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/2000NIMPB.172..847S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000NIMPB.172..847S"><span>7Be and 10Be concentrations in recent firn and ice at Law Dome, Antarctica</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Smith, A. M.; Fink, D.; Child, D.; Levchenko, V. A.; Morgan, V. I.; Curran, M.; Etheridge, D. M.; Elliott, G.</p> <p>2000-10-01</p> <p>Over the past three years, the Australian National Tandem for Applied Research (ANTARES) AMS facility at ANSTO has been expanding its sample preparation and measurement capability, particularly for 10Be, <span class="hlt">26</span><span class="hlt">Al</span> and <span class="hlt">36</span><span class="hlt">Cl</span>. During this time, ANSTO has continued its collaboration with the AAD and CSIRO Atmospheric Research on the measurement of cosmogenic isotopes from Law Dome, Antarctica. This research program has been supported by the construction of a dedicated geochemistry laboratory for the processing of ice and rock samples for the preparation of AMS targets. Here we present our first results for 10Be concentrations measured in ice cores from three sites at Law Dome and describe the sample processing protocol and aspects of the AMS measurement procedure. These sites are characterised by an eightfold difference in accumulation rate with a common precipitation source. In combination with an established ice chronology, this has enabled some preliminary findings concerning the relationship between the snow accumulation rate and the measured 10Be concentration for Law Dome during recent times. Additionally, we present 7Be and 10Be/ 7Be measurements made for a few surface snow samples from Law Dome and Australia.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.4163S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.4163S"><span>Low 10Be concentrations in geomorphic studies: Problems, strategies, and examples</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Savi, Sara; Tofelde, Stefanie; Wittmann, Hella; Binnie, Steven; Heinze, Stefan; Schildgen, Taylor</p> <p>2016-04-01</p> <p>In the last two decades, the use of in situ cosmogenic nuclides for the quantification of exogenic processes and the determination of exposure ages of landforms has seen a fast and broad expansion. Among the group of terrestrial cosmogenic nuclides that can be used to study geomorphic processes (e.g. 10Be, <span class="hlt">26</span><span class="hlt">Al</span>, <span class="hlt">36</span><span class="hlt">Cl</span>, 3He, 21Ne and 22Ne), in situ-produced 10Be is the most widely used, especially for the quantification of denudation rates. However, there are a number of problematic issues related to the use of cosmogenic nuclide techniques in rapidly evolving landscapes because of the typically low 10Be abundancies. The difficulties encountered in these settings are mainly related to (1) the mass of clean quartz that can be obtained and thus the total amount of 10Be available, and (2) the backgrounds of the sample preparation and measurement processes. In order to improve measurements in these circumstances, a series of steps can be taken into consideration during field work and sample preparation to help improve the final results. We discuss the quality of the blanks, blank corrections, and the limits of detection of the technique in the specific case of low concentration samples. Based on a number of different synthetic scenarios, we demonstrate the importance of blank corrections and utility of determination limits, and we highlight how these parameters may affect the reliability and meaningfulness of the results. This information in turn helps to illustrate how low-concentration data should be interpreted and reported.</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>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/2007GGG.....8.8003V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007GGG.....8.8003V"><span>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://hdl.handle.net/2060/20050185664','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20050185664"><span>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/2005NuPhA.758..276C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005NuPhA.758..276C"><span>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('http://adsabs.harvard.edu/abs/2012M%26PS...47.1998L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012M%26PS...47.1998L"><span>Short-lived radioactivity in the early solar system: The Super-AGB star hypothesis</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lugaro, Maria; Doherty, Carolyn L.; Karakas, Amanda I.; Maddison, Sarah T.; Liffman, Kurt; García-Hernández, D. A.; Siess, Lionel; Lattanzio, John C.</p> <p>2012-12-01</p> <p>The composition of the most primitive solar system condensates, such as calcium-aluminum-rich inclusions (CAIs) and micron-sized corundum grains, show that short-lived radionuclides (SLR), e.g., <span class="hlt">26</span><span class="hlt">Al</span>, were present in the early solar system. Their abundances require a local or stellar origin, which, however, is far from being understood. We present for the first time the abundances of several SLR up to 60Fe predicted from stars with initial mass in the range approximately 7-11 M⊙. These stars evolve through core H, He, and C burning. After core C burning they go through a "Super"-asymptotic giant branch (Super-AGB) phase, with the H and He shells activated alternately, episodic thermal pulses in the He shell, a very hot temperature at the base of the convective envelope (approximately 108 K), and strong stellar winds driving the H-rich envelope into the surrounding interstellar medium. The final remnants of the evolution of Super-AGB stars are mostly O-Ne white dwarfs. Our Super-AGB models produce <span class="hlt">26</span><span class="hlt">Al</span>/27Al yield ratios approximately 0.02-0.26. These models can account for the canonical value of the <span class="hlt">26</span><span class="hlt">Al</span>/27Al ratio using dilutions with the solar nebula of the order of 1 part of Super-AGB mass per several 102 to several 103 of solar nebula mass, resulting in associated changes in the O-isotope composition in the range Δ17O from 3 to 20‰. This is in agreement with observations of the O isotopic ratios in primitive solar system condensates, which do not carry the signature of a stellar polluter. The radionuclides <span class="hlt">41</span><span class="hlt">Ca</span> and 60Fe are produced by neutron captures in Super-AGB stars and their meteoritic abundances are also matched by some of our models, depending on the nuclear and stellar physics uncertainties as well as the meteoritic experimental data. We also expect and are currently investigating Super-AGB production of SLR heavier than iron, such as 107Pd.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1996ApJ...466.1026H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1996ApJ...466.1026H"><span>Astrophysical Site of the Origin of the Solar System Inferred from Extinct Radionuclide Abundances</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Harper, Charles L., Jr.</p> <p>1996-08-01</p> <p>Extinct radionuclides in the solar abundance distribution (SAD) provide a basis with which to characterize the molecular cloud environment in which the solar system formed 4566±2 Ma ago. The low abundance of the longer-lived r-process radionuclide 129I(T½ = 16 Ma) indicates a long (˜ 102 Ma) isolation time from energetic interstellar medium (ISM) reservoirs containing most of the Galaxy's budget of freshly-synthesized Type II supernova products. However, the abundances of the shorter-lived species 60Fe (T½ = 1.5 Ma), 53Mn (T½ = 3.7 Ma), and 107Pd (T½ = 6.5 Ma) are consistent with late admixture of freshly synthesized Type II supernova products. The fit for these species is based on an average yield distribution obtained by decomposition of the SAD. The apparent timescale contradiction is resolved in a simple two timescale molecular cloud self-contamination model consistent with formation of the Sun in an old evolved stellar complex at the eroding boundary of a molecular cloud interacting with an adjacent OB association. Admixture of an ˜10-5 to ˜10-6 mass fraction of Type II supernova ejecta into the presolar cloud dominates the shorter-lived species and 107Pd, whereas longer- lived 129I preserves information on the longer timescale constraining the mean isolation/condensation/ accretion age of the molecular material in the protosolar reservoir. The inferred model age of nucleosynthetic isolation in the long timescale is consistent with cyclicity in the nucleosynthesis rate in an orbiting ISM parcel controlled by galactic spiral structure and beads-on-a-string organization of star formation in "stellar complexes" in arms. Abundant <span class="hlt">26</span><span class="hlt">Al</span> (T½ = 0.7 Ma) in the early solar system at ˜102 times the model prediction may point to <span class="hlt">26</span><span class="hlt">Al</span>/27Al ratio of ˜0.2 in the source, or an ˜102 times greater mixing fraction for pre-explosion winds over postexplosion ejecta. A mass-losing low-mass asymptotic giant branch (AGB) star model can be tuned to account for <span class="hlt">41</span><span class="hlt">Ca</span>, <span class="hlt">26</span><span class="hlt">Al</span></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>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://www.osti.gov/scitech/servlets/purl/1255183','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1255183"><span>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/1994PhDT.......218H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1994PhDT.......218H"><span>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('https://www.ncbi.nlm.nih.gov/pubmed/2371271','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/2371271"><span>Accelerator mass spectrometry in biomedical dosimetry: relationship between low-level exposure and covalent binding of heterocyclic amine carcinogens to DNA.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Turteltaub, K W; Felton, J S; Gledhill, B L; Vogel, J S; Southon, J R; Caffee, M W; Finkel, R C; Nelson, D E; Proctor, I D; Davis, J C</p> <p>1990-07-01</p> <p>Accelerator mass spectrometry (AMS) is used to determine the amount of carcinogen covalently bound to mouse liver DNA (DNA adduct) following very low-level exposure to a 14C-labeled carcinogen. AMS is a highly sensitive method for counting long-lived but rare cosmogenic isotopes. While AMS is a tool of importance in the earth sciences, it has not been applied in biomedical research. The ability of AMS to assay rare isotope concentrations (10Be, 14C, <span class="hlt">26</span><span class="hlt">Al</span>, <span class="hlt">41</span><span class="hlt">Ca</span>, and 129I) in microgram amounts suggests that extension to the biomedical sciences is a natural and potentially powerful application of the technology. In this study, the relationship between exposure to low levels of 2-amino-3,8-dimethyl[2-14C]imidazo[4,5-f]quinoxaline and formation of DNA adducts is examined to establish the dynamic range of the technique and the potential sensitivity for biological measurements, as well as to evaluate the relationship between DNA adducts and low-dose carcinogen exposure. Instrument reproducibility in this study is 2%; sensitivity is 1 adduct per 10(11) nucleotides. Formation of adducts is linearly dependent on dose down to an exposure of 500 ng per kg of body weight. With the present measurements, we demonstrate at least 1 order of magnitude improvement over the best adduct detection sensitivity reported to date and 3-5 orders of magnitude improvement over other methods used for adduct measurement. An additional improvement of 2 orders of magnitude in sensitivity is suggested by preliminary experiments to develop bacterial hosts depleted in radiocarbon. Expanded applications involving human subjects, including clinical applications, are now expected because of the great detection sensitivity and small sample size requirements of AMS.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2000SSRv...92..113N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000SSRv...92..113N"><span>Short-Lived Radionuclides in Meteorites: Constraints on Nebular Timescales for the Production of Solids</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nichols, Robert H., Jr.</p> <p>2000-04-01</p> <p>Variations in the abundances of short-lived radionuclides such as <span class="hlt">26</span><span class="hlt">Al</span> (τ1/2 ≈ 0.74 Ma) and 53Mn (τ1/2 ≈ 3.7 Ma) in meteoritic solids may be used to infer relative formation intervals of these solids in the nebula at precisions of less than 1 Ma. In a strict chronometric interpretation of the isotopic variations, whereby criteria such as spatial and temporal isotopic homogeneity and closed system isotopic evolution are met, solid formation occurred in the nebula for at least several million years. This is longer than some theoretical and astronomical estimates for the duration of the active nebula. The evidence for live <span class="hlt">41</span><span class="hlt">Ca</span> (τ1/2 ≈ 0.10 Ma) in meteoritic inclusions further indicates that the onset of solid formation occurred quite early, perhaps within a few hundred thousand years after the onset of the collapse of the sun's parent molecular cloud. Failure of the chronometric interpretation may arise for a variety of reasons, including but not limited to, the late, inhomogeneous injection of material from a nearby stellar source or the local production of short-lived radionuclides by an energetic particle irradiation, e. g., from T Tauri (X-wind) or galactic cosmic ray sources. Although some isotopic evidence exists that the criteria required for a strict chronometric interpretation are not met by each of the short-lived chronometers, there is no compelling reason to shorten the interval of solid formation in the nebula to less than 1 Ma.</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('http://www.osti.gov/scitech/servlets/purl/803430','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/803430"><span>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://www.osti.gov/scitech/servlets/purl/10123679','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/10123679"><span>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('https://www.ncbi.nlm.nih.gov/pubmed/25409284','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25409284"><span>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>2014-12-03</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('https://www.ncbi.nlm.nih.gov/pubmed/26269327','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26269327"><span>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.</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>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>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://pubs.er.usgs.gov/publication/70020412','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70020412"><span>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('https://www.osti.gov/scitech/biblio/21336023','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21336023"><span>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('https://www.osti.gov/scitech/biblio/943071','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/943071"><span>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/2014AGUFMEP53A3627P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMEP53A3627P"><span>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('https://www.osti.gov/scitech/biblio/22356503','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22356503"><span>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('https://www.ncbi.nlm.nih.gov/pubmed/22031277','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22031277"><span>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://www.osti.gov/scitech/servlets/purl/137513','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/137513"><span>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('https://www.ncbi.nlm.nih.gov/pubmed/3010078','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/3010078"><span>gamma-Aminobutyric acid agonists and antagonists alter chloride flux across brain membranes.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Allan, A M; Harris, R A</p> <p>1986-05-01</p> <p>gamma-Aminobutyric acid (GABA), the major inhibitory neurotransmitter in the mammalian brain, increases membrane chloride conductance. Previously, we reported that GABA increases <span class="hlt">36</span><span class="hlt">Cl</span>- uptake by membrane vesicles (microsacs) prepared from mouse brain. Employing this technique, we found that the GABAA agonists, muscimol, isoguvacine, 4,5,6,7-tetrahydroisoxazolo(5,4-C)pyridine-3-ol, and 3-amino-1-propane sulfonate, all produced a concentration-dependent increase in <span class="hlt">36</span><span class="hlt">Cl</span>- influx, but baclofen, a GABAB agonist, failed to alter <span class="hlt">36</span><span class="hlt">Cl</span>- flux. Inhibition of GABA-dependent <span class="hlt">36</span><span class="hlt">Cl</span>- influx was produced by the convulsant drugs, bicuculline, picrotoxin, and pentylenetetrazole. Ion specificity was demonstrated by a failure of GABA agonists to stimulate influx of 45Ca2+, 86Rb+, 22Na+, or 35SO4(2). GABA-stimulated uptake of <span class="hlt">36</span><span class="hlt">Cl</span>- was largest in cortex and cerebellum and smaller in hippocampus and striatum. There was little difference in sensitivity to GABA among the areas. Analysis of subcellular fractions prepared from mouse brain demonstrated that the GABA-dependent <span class="hlt">36</span><span class="hlt">Cl</span>- influx was enriched in the synaptosomal fraction. The nonspecific (GABA-independent) uptake of <span class="hlt">36</span><span class="hlt">Cl</span>- was enriched in the myelin fraction. These experiments provide evidence for a functional coupling among GABA receptors and the chloride ionophore and suggest that the GABA-activated chloride channel is a site of action for several convulsant compounds.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4926806','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4926806"><span>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.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</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>2016-01-01</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 Using <span class="hlt">41</span><span class="hlt">Ca</span> tracer methodology, determine if 4 servings/d of dairy foods results in greater <span class="hlt">41</span><span class="hlt">Ca</span> retention than an equivalent amount of calcium and vitamin D from supplements. Secondary objective was to evaluate the time course for the change in <span class="hlt">41</span><span class="hlt">Ca</span> retention. Methods In this crossover trial, postmenopausal women (n=12) were dosed orally with 100nCi of <span class="hlt">41</span><span class="hlt">Ca</span> and after a 180 day equilibration period received dairy (4 servings/d of milk or yogurt; ~1300 mg calcium, 400 IU cholecalciferol (vitamin D3/d)) or supplement treatments (1200 mg calcium carbonate/d and 400 IU vitamin D3/d) in random order. Treatments lasted 6 wks separated by a 6 wk washout (WO). Calcium was extracted from weekly 24 hr urine collections; accelerator mass spectrometry (AMS) was used to determine the 41/40Ca ratio. Primary outcome was change in 41/40Ca excretion. Secondary outcome was the time course for change in <span class="hlt">41</span><span class="hlt">Ca</span> excretion during intervention and WO periods. Results The 41/40Ca ratio decreased significantly over time during both treatments; there was no difference between treatments. Both treatments demonstrated a significant retention of <span class="hlt">41</span><span class="hlt">Ca</span> within 1-2 wks (p = 0.0007 and p < 0.001 for dairy and supplements, respectively). WO demonstrated a significant decrease (p = 0.0024) in <span class="hlt">41</span><span class="hlt">Ca</span> retention within 1-2 wk, back to pre-intervention levels. Conclusion These data demonstrate that urinary <span class="hlt">41</span><span class="hlt">Ca</span> retention is increased with an increase in calcium and vitamin D intake regardless of the source of calcium, and the increased retention occurs within 1-2 wks. PMID:27376110</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>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>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 [Oakland, CA; Vogel, John S [San Jose, CA; Fitzgerald, Robert L [Encinitas, CA; Deftos, Leonard J [Del Mar, CA; Herold, David [Del Mar, CA; Burton, Douglas W [San Diego, CA</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('https://www.osti.gov/scitech/biblio/6965325','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6965325"><span>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> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24144617','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24144617"><span>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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040065906&hterms=sodalite&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dsodalite','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040065906&hterms=sodalite&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dsodalite"><span>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> </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('https://www.osti.gov/scitech/biblio/569385','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/569385"><span>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://adsabs.harvard.edu/abs/2002HydJ...11..217D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002HydJ...11..217D"><span>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://www.osti.gov/scitech/servlets/purl/894191','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/894191"><span>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('https://www.ncbi.nlm.nih.gov/pubmed/7151761','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/7151761"><span>Metabolism and pharmacokinetics of alternate drinking water disinfectants.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Abdel-Rahman, M S; Couri, D; Bull, R J</p> <p>1982-12-01</p> <p>The chlorination of surface waters is known to elevate trihalomethanes; consequently, chlorine dioxide (ClO2) is being considered as an alternative disinfectant. The primary products resulting from ClO2 disinfection of waters are chlorites (ClO2-) and chlorates (ClO3-). Studies in rats revealed that ClO2 is converted to chloride (Cl-), ClO2- and ClO3-. ClO2- and ClO3- are excreted as Cl-, ClO2- and Cl-, ClO2-, ClO3-, respectively. Radioactivity was rapidly absorbed from the gastrointestinal tract following the administration of <span class="hlt">36</span><span class="hlt">Cl</span>O2 orally, and the half-life for the elimination of <span class="hlt">36</span><span class="hlt">Cl</span> from the rat was 44 hr, corresponding to a rate constant of 0.016/hr. After 72 hr, radioactivity was highest in plasma, followed by kidney, lung, and stomach. <span class="hlt">36</span><span class="hlt">Cl</span> in plasma reached a peak at 2 hr and 1 hr after oral administration of <span class="hlt">36</span><span class="hlt">Cl</span>O2- and <span class="hlt">36</span><span class="hlt">Cl</span>O3-, respectively. <span class="hlt">36</span><span class="hlt">Cl</span> excretion was greatest 24 hr after the administration of <span class="hlt">36</span><span class="hlt">Cl</span>O3-, but in the case of <span class="hlt">36</span><span class="hlt">Cl</span>O2-, the excretion probably represented saturation of the biotransformation and excretion pathway. A low activity in packed cells compared to plasma was detected in chlorate ingestion, rather than an even distribution in chlorite treatment. Chloroform determinations in rat blood after one year indicated that chloroform was significantly higher than control in the 100 and 1000 mg/l. ClO2 groups. However, no significant values were observed in the 1 or 10 mg/l. ClO2 and ClO2 metabolites groups. ClO2 and its metabolites are eliminated from the body more rapidly than chlorine, and they do not appear to increase trihalomethane concentrations at low dosages.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/674566','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/674566"><span>Modeling flow and transport pathways to the potential repository horizon at Yucca Mountain</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Wolfsberg, A.V.; Roemer, G.J.C.; Fabryka-Martin, J.T.; Robinson, B.A.</p> <p>1998-09-01</p> <p>The isotopic ratios of {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>/Cl are used in conjunction with geologic interpretation and numerical modeling to evaluate flow and transport pathways, processes, and model parameters in the unsaturated zone at Yucca Mountain. By synthesizing geochemical and geologic data, the numerical model results provide insight into the validity of alternative hydrologic parameter sets, flow and transport processes in and away from fault zones, and the applicability of {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>/Cl ratios for evaluating alternative conceptual models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/780417','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/780417"><span>MODELING FLOW AND TRANSPORT PATHWAYS TO THE POTENTIAL REPOSITORY HORIZON AT YUCCA MOUNTAIN</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Wolfsberg, A. V.; Fabryka-Martin, J. T.; Roemer, G. J.C.; Robinson, B. A.</p> <p>1998-03-04</p> <p>The isotopic ratios of {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>/Cl are used in conjunction with geologic interpretation and numerical modeling to evaluate flow and transport pathways, processes, and model parameters in the unsaturated zone at Yucca Mountain. By synthesizing geochemical and geologic data, the numerical model results provide insight into the validity of alternative hydrologic parameter sets, flow and transport processes in and away from fault zones, and the applicability of {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>/Cl. ratios for evaluating alternative conceptual models.</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>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('https://www.ncbi.nlm.nih.gov/pubmed/19806723','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19806723"><span>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.</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>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('https://www.osti.gov/scitech/biblio/5403593','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5403593"><span>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://pubs.er.usgs.gov/publication/70022217','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70022217"><span>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://adsabs.harvard.edu/abs/1995Metic..30R.541M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1995Metic..30R.541M"><span>Investigation of Low-Energy Neutrons and Their Reaction Products in Planetary Objects</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Masarik, J.; Reedy, R. C.</p> <p>1995-09-01</p> <p>High precision W, Nd, and Sm isotopic analyses [1,2] used for precise age determination of the earliest episodes of planetary differentiation require an understanding of possible contributions from neutron-capture reactions to the production of the investigated isotopes. Low-energy neutrons can also be used to study the surface composition of the planets [3,4]. Neutron-capture production profiles, which are very different from those for tracks or from nuclides made by energetic cosmic ray particles, can be used for unfolding the cosmic-ray exposure history of meteorites [5]. We did Monte Carlo numerical simulations of the influence of chemical composition, temperature and water content on neutron fluxes and production of cosmogenic isotopes. The LAHET Code System [6] was used to numerically simulate the irradiation of various objects by galactic-cosmic-ray particles and to calculate neutron fluxes and production rates of various W, Sm, Nd, Gd isotopes and 59Ni, 60Co, <span class="hlt">36</span><span class="hlt">Cl</span>, <span class="hlt">41</span><span class="hlt">Ca</span>, 80Kr and 82Kr. The advantage of these calculations is that the physical model applied to the investigation of particle production and transport uses only basic physical quantities and parameters without including any free parameters and assumptions about the neutron source term, as was necessary in older approaches [7,8]. Our simulations started by selecting the energy and direction of the primary particle that starts the particle cascade. As neutrons produced in the cascade are followed down to the thermal energies, we are able to determine the main sources of observed differences in capture rates. The calculations were validated by modeling [9] ^(60)Co [10] and <span class="hlt">41</span><span class="hlt">Ca</span> [11] measured in lunar samples. For the surface temperature variations during the lunar day, which range from about 120 K to 400 K, we found that the effect on production rates is very small. Temperature influences only relative capture rates of isotopes whose thermal capture cross sections differ from a 1/v dependence. For</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>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>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://pubs.er.usgs.gov/publication/70022085','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70022085"><span>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://adsabs.harvard.edu/abs/1998GeCoA..62..433S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1998GeCoA..62..433S"><span>Cosmogenic Chlorine-36 Production in Calcite by Muons</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Stone, J. O. H.; Evans, J. M.; Fifield, L. K.; Allan, G. L.; Cresswell, R. G.</p> <p>1998-02-01</p> <p>At depths below a few metres, <span class="hlt">36</span><span class="hlt">Cl</span> production in calcite is initiated almost entirely by cosmic ray muons. The principal reactions are (1) direct negative muon capture by Ca; 40Ca(μ -,α) <span class="hlt">36</span><span class="hlt">Cl</span>, and (2) capture by 35Cl of secondary neutrons produced in muon capture and muon-induced photodisintegration reactions. We have determined rates for <span class="hlt">36</span><span class="hlt">Cl</span> and neutron production due to muon capture in calcite from a 20 m (5360 g cm -2) depth profile in limestone. The <span class="hlt">36</span><span class="hlt">Cl</span> yield from muon capture by Ca in pure calcite is 0.012 ± 0.002 atom per stopped negative muon. The surface production rate of <span class="hlt">36</span><span class="hlt">Cl</span> by muon capture on Ca in calcite is, therefore, 2.1 ± 0.4 atom g -1a -1 at sea level and high latitude, approximately 11% of the production rate by Ca spallation. If it is assumed that 34% of the negative muons are captured by the Ca atom in calcite, the α-yield from 40Ca following muon capture is 0.043 ± 0.008, somewhat lower than the result of a recent muon irradiation experiment (0.062 ± 0.020), but well within the extremes of existing theoretical predictions (0.0033-0.15). The average neutron yield following muon capture in pure calcite is 0.44 ± 0.15 secondary neutrons per stopped negative muon, in good agreement with existing theoretical predictions. Cosmogenic isotope production by muons must be taken into account when dating young geomorphic surfaces, especially those created by excavation of only a few metres of overlying rock. Attention to isotope production by muons is also crucial to determining surface erosion rates accurately. Due to the deep penetration of muons compared to cosmic ray hadrons, the accumulation of muon-produced <span class="hlt">36</span><span class="hlt">Cl</span> is less sensitive to erosion than that of spallogenic <span class="hlt">36</span><span class="hlt">Cl</span>. Although production by muons at the surface is only a small fraction of production by spallation, the fraction of muon-produced <span class="hlt">36</span><span class="hlt">Cl</span> in rapidly eroding limestone surfaces can approach 50%. In such cases, erosion rates estimated using conventional models which attribute</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>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://www.osti.gov/scitech/servlets/purl/765661','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/765661"><span>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> <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>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://adsabs.harvard.edu/abs/2016BVol...78...35A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016BVol...78...35A"><span>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> </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://adsabs.harvard.edu/abs/2007AGUFMPP33B1271W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AGUFMPP33B1271W"><span>Signatures of Glacial Erosion and Retreat in the Landscape: Cosmogenic and Numerical Modeling Constraints</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ward, D. J.; Anderson, R. S.; Briner, J. P.; Guido, Z. S.</p> <p>2007-12-01</p> <p>We use cosmogenic radionuclide (CRN) exposure ages to constrain numerical simulations of deglaciation histories in the Middle Boulder Creek drainage, Colorado Front Range, and the Animas River valley, San Juan Mountains, Colorado. We present 18 new 10Be exposure ages from glacially polished bedrock sampled in the Middle Boulder Creek valley. All of these ages are younger than the ~19-22 ka terminal moraine age based on <span class="hlt">26</span><span class="hlt">Al</span> and <span class="hlt">36</span><span class="hlt">Cl</span> measurements by Schildgen (2000) and Benson et al. (2005). Exposure ages decrease with distance upvalley from the moraine, and the youngest ages in the uppermost valley are uniformly ~13 ka. We include 4 10Be ages in a cross section across the mid-valley, which show a pattern of Last Glacial Maximum (LGM) ages (12-14 ka) within the glacial footprint, and older exposure ages (~40 ka) near the trim lines. A similar age trend is seen in the Animas River valley in southwestern Colorado, which was occupied by a lobe of the LGM ice sheet that capped the San Juan mountains. Deglaciation began here ca. 19.4 ka, based on a 10Be depth profile in a proglacial terrace. A longitudinal transect of exposure ages from glacially polished samples indicates that terminus retreat proceeded at ~15 m/yr until complete deglaciation ca. 12.3 ka. Neither valley has obvious recessional deposits within the LGM glacial footprint. The first-order trend in each valley is a monotonic glacial retreat, but there are other possible retreat scenarios. For instance, we would like to test whether the same trend in 10Be concentrations could be generated by episodic retreat punctuated by periods of readvance. To investigate these scenarios, we modified the GC2D numerical glacier simulation (see Kessler et al., 2006) to incorporate a CRN accumulation layer. This layer can contain any starting value of CRN concentration. Production over each timestep is scaled to DEM latitude and altitude. Production is taken to be zero in areas covered by more than 10 m of ice. The CRN</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>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://www.osti.gov/scitech/servlets/purl/15013414','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/15013414"><span>The Search for Meterorites with Complex Exposure Histories Amoung Ordinary Chondrites with Low 3HE/21NE Ratios</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Welton, K C; Nishiizumi, K; Caffee, M W</p> <p>2001-04-30</p> <p>}Ne ratios may be due to high shielding conditions in objects with radii > 1m [5]. To elucidate these issues, we selected 15 samples with known noble gas concentrations [6] for radionuclide studies and obtained aliquots of the samples adjacent to those measured for noble gases. The specific goal is the identification of complex exposure histories among samples having low {sup 3}He/{sup 21}Ne ratios. All samples have {sup 3}He deficiencies of >20% relative to the ''Bern-line'' (Table 1). Most of the selected samples also have low {sup 22}Ne/{sup 21}Ne ratios ({le}1.1), indicative of high shielding during most of their cosmic-ray exposure (Table 1), whereas one sample (Suizhou) was selected because of its relatively low {sup 81}Kr concentration [7]. In addition, we selected QUE 93021, for which initial radionuclide results suggested a short exposure age. Here we present 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 stone and metal fractions for the 16 ordinary chondrites listed in Table 1.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1995Metic..30R.584S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1995Metic..30R.584S"><span>Noble Gases in the Lunar Meteorites Calcalong Creek and QUE 93069</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Swindle, T. D.; Burkland, M. K.; Grier, J. A.</p> <p>1995-09-01</p> <p>Although the world's collections contain comparable numbers of martian and lunar meteorites (about 10 each), their ejection histories seem to be quite different [1]. We have sampled no more than four martian craters, but almost every one of the lunar meteorites apparently represents a separate cratering event. Furthermore, most lunar meteorites were apparently ejected from the top meter of the surface, unlike any of the martian meteorites. We have measured noble gases in two bulk samples of the lunar meteorite QUE93069 and three of Calcalong Creek, ranging in size from 7 to 15 mg. Averaged results are given in Table 1. Both meteorites contain solar-wind-implanted noble gas. QUE 93069, which is a mature anorthositic regolith breccia [2], contains amounts comparable to the most gas-rich lunar meteorites. The relatively low 40Ar/36Ar ratios of both meteorites suggest surface exposures no more than 2.5 Ga ago [3]. Calcalong Creek has readily observable spallogenic gas. The 131Xe/126Xe ratio of 4.8+/-0.3 corresponds to an average shielding depth of slightly more than 40 gm/cm^2 [4]. In common with many lunar breccias, Calcalong Creek has been exposed to cosmic rays for several hundred Ma (calculations based on [4] and [5]). The 3He apparent exposure age is much shorter, suggesting diffusive loss of He. To determine the detailed exposure history, it is necessary to have measurements of cosmogenic radionuclides. Our samples were too small to measure 81Kr, but [6] have measured 10Be, <span class="hlt">26</span><span class="hlt">Al</span> and <span class="hlt">36</span><span class="hlt">Cl</span>. Their data are consistent with either extended exposure at <70 gm/cm^2 in the lunar regolith followed by a short (200,000 years) transit to Earth, or with ejection from several meters depth about 2 Ma ago [6]. Our data, requiring several hundred Ma of exposure at an average depth of 40-50 gm/cm^2, are clearly more consistent with the first scenario. The only other lunar meteorite which could have been ejected at the same time is MAC 88104/5 [1], but the chemical differences</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>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>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('http://adsabs.harvard.edu/abs/2015NIMPB.361..627M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015NIMPB.361..627M"><span>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('https://www.osti.gov/scitech/biblio/7036815','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/7036815"><span>Ethanol potentiation of GABAergic transmission in cultured spinal cord neurons involves gamma-aminobutyric acidA-gated chloride channels</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Mehta, A.K.; Ticku, M.K.</p> <p>1988-08-01</p> <p>The interaction of ethanol with gamma-aminobutyric acid (GABA)-mediated <span class="hlt">36</span>-<span class="hlt">Cl</span>-influx and its modulation by various drugs was investigated in C57 mice spinal cord cultured neurons. Ethanol (5-100 mM) potentiated the effect of GABA on /sup <span class="hlt">36</span>/<span class="hlt">Cl</span>-influx; whereas at concentrations greater than or equal to 50 mM ethanol activated Cl- channels directly. The effect of ethanol was specific for GABAA receptor-gated Cl- channels, as ethanol did not potentiate glycine-induced /sup <span class="hlt">36</span>/<span class="hlt">Cl</span>-influx in the same neurons. Both the enhancing and direct effects of ethanol on /sup <span class="hlt">36</span>/<span class="hlt">Cl</span>-influx were blocked by GABA antagonists like bicuculline, picrotoxinin and inverse agonists of the benzodiazepine site like the imidazodiazepine R015-4513 (ethyl-8-azido-5,6-dihydro-5-methyl-6-oxo-4H-imidazo (1,5 alpha), (1,4)benzodiazepine-3-carboxylate) and N-methyl-beta-carboline-3-carboxamide (FG-7142). Ethanol potentiating effect of GABA-induced /sup <span class="hlt">36</span>/<span class="hlt">Cl</span>-influx was also reversed by methyl-6,7-dimethyl-4-ethyl-beta-carboline-3-carboxylate. The effects of the inverse agonists were blocked by the benzodiazepine receptor antagonist R015-1788. Both R015-4513 and FG-7142 reversed direct and GABA potentiating effects of ethanol effect at concentrations lower than those that exhibit inverse agonistic activity in the /sup <span class="hlt">36</span>/<span class="hlt">Cl</span>-influx assay in cultured neurons. These results suggest that ethanol facilitation of GABAAergic transmission involves GABA receptor-gated Cl- channels and that this interaction may be responsible for some of the pharmacological effects of ethanol.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JPhCS.755a2025K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JPhCS.755a2025K"><span>Temperature-time induced changes in magnetic properties of multi-component Fe78Si3.6C13.4Mn0.65B4.35 alloy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kane, S. N.; Modak, S. S.; Shah, M.; Satalkar, M.; Gehlot, K.; Ghodke, N.; Araujo, J. P.; Varga, L. K.</p> <p>2016-10-01</p> <p>Influence of thermal annealing as a function of temperature and time, on magnetic and structural properties of Fe78Si3.6Cl3.4Mn0.65B4.35 (Fe78Si3.6Cl3.4Mn0.65 = Ci) alloy has been reported. Information on structure, formed nano-crystalline phases and their correlation with magnetic properties has been studied using, magnetic measurements, differential scanning calorimetery (DSC) and x-ray diffraction (XRD). Thermal annealing treatment leads to rather coarse grain microstructure (∼31 nm) accompanied by surface crystallization that appears to deteriorate the magnetic properties with annealing temperature.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1994NIMPB..92..134K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1994NIMPB..92..134K"><span>The PRIME Lab gas ionization detector</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Knies, David L.; Elmore, David</p> <p>1994-06-01</p> <p>A gas ionization detection system was built for optimal identification of AMS radionuclides, in particular 10Be and <span class="hlt">36</span><span class="hlt">Cl</span>. For <span class="hlt">36</span><span class="hlt">Cl</span>, a combination of 1) the difference in arrival times for electrons at two anode plates and 2) a novel split anode plate has led to a reduction in misidentified 36S. A peak-stabilizing routine incorporated in the data acquisition system has allowed us to run at higher counting rates. Changing to propane gas has reduced random signal amplitude shifts.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21562555','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21562555"><span>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('https://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="https://www.osti.gov/pages/biblio/1259784-bone-equally-responsive-calcium-vitamin-intake-from-food-vs-supplements-use-tracer-kinetic-model"><span>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.; ...</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> <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>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('http://adsabs.harvard.edu/abs/1990NIMPB..52..233F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1990NIMPB..52..233F"><span>Accelerator mass spectrometry at the Australian National University's 14UD accelerator: experience and developments</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fifield, L. K.; Ophel, T. R.; Allan, G. L.; Bird, J. R.; Davie, R. F.</p> <p>1990-12-01</p> <p>Although the major emphasis of the joint ANU/ANSTO accelerator mass spectrometry program has been the measurement of <span class="hlt">36</span><span class="hlt">Cl</span> samples, both 14C and 10Be capabilities have been implemented recently on the 14UD accelerator. The new developments and operating experience are reviewed.</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>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://www.osti.gov/scitech/servlets/purl/555352','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/555352"><span>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.osti.gov/scitech/biblio/572205','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/572205"><span>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://pubs.er.usgs.gov/publication/70023717','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70023717"><span>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://adsabs.harvard.edu/abs/2010AGUFM.T33A2203P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFM.T33A2203P"><span>Deriving Fault Slip Histories From Cosmogenic Exposure Ages Along Bedrock Fault Scarps Using Synthetic And Natural Data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Phillips, R. J.; Cowie, P. A.; Walker, M. J.; Roberts, G.; Dunai, T. J.; Zijerveld, L.; Wilkinson, M. W.; McCaffrey, K. J.; Bubeck, A. A.</p> <p>2010-12-01</p> <p>Cosmogenic surface exposure dating is a powerful tool for reconstructing long term slip rates on active faults and may provide evidence for temporal earthquake clustering (e.g. Benedetti et al., GRL, v.29, 2002). Extensional faults in limestone are particularly amenable to this type of study because they commonly produce a striated bedrock scarp, exhumed by faulting, that can be sampled to obtain the cosmogenic <span class="hlt">36</span><span class="hlt">Cl</span> concentration as a function of throw. The number of earthquakes, their timing and the magnitude of the associated slip strongly influence the shape of <span class="hlt">36</span><span class="hlt">Cl</span> profile. Existing methods for extracting paleo-earthquake records from such data use forward modelling and conclude that individual slip events ≥1m (≥ Magnitude 7.0) may be resolved although a cluster of smaller magnitude events produce a similar <span class="hlt">36</span><span class="hlt">Cl</span> variation. Due to uneven scarp preservation sample spacing in real data sets is variable (up to 10’s cm), further limiting our ability to extract tectonic information. Here we carry out a Monte Carlo inversion on synthetic <span class="hlt">36</span><span class="hlt">Cl</span> data sets to investigate the effect of sample spacing and analytical error on the interpretation of fault slip histories. We transform the <span class="hlt">36</span><span class="hlt">Cl</span> concentration versus height data into a linear form. For a given set of fault slip events, event timings are determined using least squares inversion of the linearised data. By searching all possible combinations of slip event size (ranging from the sampling interval to the total scarp height), and using a range of different statistical measures for the goodness of fit, we rank the best fit scenario(s). By applying this approach to synthetic <span class="hlt">36</span><span class="hlt">Cl</span> profiles, generated using a numerical fault growth model, we show how sample density and analytical error influence our interpretation of the true slip history (which for the synthetic data is known). We find that determining the timing of specific earthquakes requires (quasi-) uniform as well as dense sampling (5cm spacing), whereas long</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..12.7111C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..12.7111C"><span>Extracting tectonic information from cosmogenic exposure ages along bedrock scarps using synthetic and natural data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cowie, Patience; Walker, Matthew; Roberts, Gerald; Phillips, Richard; Dunai, Tibor; Zijerveld, Leo; McCaffrey, Ken</p> <p>2010-05-01</p> <p>Cosmogenic surface exposure dating is a powerful tool for reconstructing long term slip histories on active faults and extracting earthquake recurrence intervals (e.g. Benedetti et al., GRL, v.29, 2002). Extensional faults are particularly amenable to this type of study because they commonly produce a striated bedrock scarp, exhumed by faulting, that can be directly dated. Bedrock scarps in limestone can be sampled to obtain the concentration of cosmogenic <span class="hlt">36</span><span class="hlt">Cl</span>, produced primarily through interactions of cosmic ray secondary neutrons and muons with Ca within the scarp limestone. To first order the production rate decreases exponentially with depth beneath the ground surface. Because each normal-faulting earthquake uplifts a new portion of the scarp above the surface, the <span class="hlt">36</span><span class="hlt">Cl</span> concentration along the scarp is the sum of that <span class="hlt">36</span><span class="hlt">Cl</span> produced below the surface prior to the earthquake and that accumulated above the surface after the earthquake. For a scarp being seismically exhumed, the characteristic profile is therefore a series of exponentials with discontinuities marking the timing of each earthquake. The number of events, their timing and the magnitude of the associated slip strongly influence the shape of <span class="hlt">36</span><span class="hlt">Cl</span> profile. Existing methods for extracting paleo-earthquakes from these data are based on a forward modelling approach and have shown that slip events ≥0.5m (≥ Magnitude 6.0) are well resolved by fully sampling the height of the exposed bedrock scarp. A forward model for <span class="hlt">36</span><span class="hlt">Cl</span> accumulation generates <span class="hlt">36</span><span class="hlt">Cl</span> concentration versus fault height for different potential fault slip histories, which is then compared with the measured <span class="hlt">36</span><span class="hlt">Cl</span> concentrations. The best fit scenario(s) are then ranked using the Aikake Information Criterion (AIC), which is sensitive to the goodness of fit as well as the number of parameters included in the model. A key feature of published results using this approach is that slip events of several meters have, in several cases, been inferred</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('https://www.ncbi.nlm.nih.gov/pubmed/20185683','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20185683"><span>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>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('https://www.osti.gov/scitech/biblio/6409361','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6409361"><span>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>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/servlets/purl/674563','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/674563"><span>Use of chlorine-36 and other geochemical data to test a groundwater flow model for Yucca Mountain, Nevada</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Wolfsberg, A.V.; Fabryka-Martin, J.T.; Levy, S.S.</p> <p>1998-09-01</p> <p>Defining the spatial distribution and timing of subsurface fluid percolation is one of the most important factors determining long term performance of the potential high-level radioactive waste repository at Yucca Mountain, Nevada. The nonwelded interval of the Paintbrush Group (PTn), which overlies most of the potential repository, has high matrix porosities and permeabilities and is mostly unfractured. The Exploratory Studies Facility (ESF) is a 8-km long, 7.6-m diameter, tunnel excavated beneath Yucca Mountain to the level of the potential repository horizon in order to provide access for characterization of these rocks. Several samples collected within the ESF have measured {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>/Cl ratios that record anthropogenic {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> (bomb-pulse {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>), indicating that at least some fraction of the water has traversed the overlying PTn in 40 years or less and that flow is not confined to the matrix of that unit. The presence of a fast path transmitting bomb-pulse {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> to depth appears to require the simultaneous presence of a structure (such as a fault) cutting the PTn and sufficiently high magnitude to surface infiltration to initiate and sustain at least a small component of fracture flow along the connected fracture path associated with the structure. The {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> data have been simulated using the flow and transport model FEHM in order to establish bounds on infiltration rates at the site and to provide greater confidence in the understanding of unsaturated flow processes at the site by showing consistency between the observed and simulated data sets. An analogous effort simulating the distribution of porewater chloride concentrations is providing an independent means for confirming the conceptual model.</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>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('http://adsabs.harvard.edu/abs/2003JCHyd..62...43C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003JCHyd..62...43C"><span>Chlorine-36 data at Yucca Mountain: statistical tests of conceptual models for unsaturated-zone flow</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Campbell, Katherine; Wolfsberg, Andrew; Fabryka-Martin, June; Sweetkind, Donald</p> <p>2003-05-01</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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/12714284','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12714284"><span>Chlorine-36 data at Yucca Mountain: statistical tests of conceptual models for unsaturated-zone flow.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Campbell, Katherine; Wolfsberg, Andrew; Fabryka-Martin, June; Sweetkind, Donald</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.</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>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://adsabs.harvard.edu/abs/2010AIPC.1269..144D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AIPC.1269..144D"><span>Massive-Star Nucleosynthesis: Lessons from INTEGRAL</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Diehl, Roland; Lang, Michael; Kretschmer, Karsten; Martin, Pierrick; Ohlendorf, Henrike; Voss, Rasmus</p> <p>2010-08-01</p> <p>Gamma-ray line observations with INTEGRAL measure decay of unstable isotopes which are ejected from sites of nucleosynthesis. Massive stars are believed to be producers of gamma-ray emitting isotopes 44Ti, <span class="hlt">26</span><span class="hlt">Al</span>, 60Fe. Measurements with the Ge spectrometer have shown that (1) inner core-collapse supernova ejecta from the Cas A supernova remnant appear to still travel at velocities beyond a few hundred km/sec (2) <span class="hlt">26</span><span class="hlt">Al</span> synthesis occurs throughout the Galaxy corresponds to a supernova rate from core collapses of about one every 50 years; (3) 60Fe synthesis expected from massive stars is above the constraints from gamma-ray observations; <span class="hlt">26</span><span class="hlt">Al</span> synthesis in the Cygnus region appears on the high side of predictions from models; <span class="hlt">26</span><span class="hlt">Al</span> emission from the nearby Sco-Cen group of stars has been identified demonstrates massive-star activity close to the Sun. <span class="hlt">26</span><span class="hlt">Al</span> gamma-rays have been used to determine a longitude-velocity distribution of the presumably hot tenuous ISM which carries <span class="hlt">26</span><span class="hlt">Al</span>, which can be compared to molecular-gas star motions to help understand the Galaxy's bar spiral-arm structure. Implications of the above nucleosynthesis constraints suggest that INTEGRAL's observed positron annihilation gamma-rays need a contribution from another source located in the central regions of our Galaxy, and/or positrons may propagate kpc-distances away from their sources before annihilating.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19824635','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19824635"><span>Chlorate metabolism in pure cultures of Escherichia coli O157:H7 pretreated with either nitrate or chlorate.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Smith, David J; Oliver, Christy E; Shelver, Weilin L; Caesar, TheCan; Anderson, Robin C</p> <p>2009-11-11</p> <p>Previous research has suggested that nitrate-respiring pathogens such as Escherichia coli O157:H7 and Salmonella spp. are susceptible to chlorate salts due to the conversion of chlorate to chlorite by respiratory nitrate reductase. This study was conducted to determine the effect of chlorate on E. coli O157:H7 growth and chlorate biotransformation and to determine whether chlorite is produced in anaerobic culture of E. coli O157:H7. Final concentrations of E. coli O157:H7 were generally decreased by about 2 log units in incubations containing > or =5 mM chlorate, except when bacteria were pretreated with 10 mM chlorate. [(<span class="hlt">36</span>)<span class="hlt">Cl</span>]Chlorate metabolism by pure cultures of E. coli O157:H7 was not measurable above chlorate concentrations of 5 mM, but measurable chlorate reduction occurred in cultures containing 0.5, 1, or 5 mM [(<span class="hlt">36</span>)<span class="hlt">Cl</span>]chlorate. Pretreatment of E. coli O157:H7 with 5 mM nitrate did not increase the rate of chlorate conversion to chloride, suggesting that nitrate did not induce nitrate reductase isoforms capable of metabolizing chlorate in E. coli O157:H7. Pure cultures of E. coli O157:H7 preconditioned with 10 mM chlorate had an attenuated ability to transform [(<span class="hlt">36</span>)<span class="hlt">Cl</span>]chlorate to [(<span class="hlt">36</span>)<span class="hlt">Cl</span>]chloride with measurable chlorate reduction only occurring in 0.5 mM chlorate treatments. The hypothesis that E. coli O157:H7 is sensitive to chlorate by virtue of the reduction of chlorate to chlorite ion (ClO(2)(-)) was supported, but not proven, by the direct measurement of low concentrations of [(<span class="hlt">36</span>)<span class="hlt">Cl</span>]ClO(2)(-) in incubation media containing 0.5 mM [(<span class="hlt">36</span>)<span class="hlt">Cl</span>]ClO(3)(-). Collectively these results indicate that growth of E. coli O157:H7 in pure culture will be reduced in the presence of 5 mM or greater concentrations of sodium chlorate and that E. coli O157:H7 is capable of producing chlorite ions during the metabolism of chlorate.</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>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>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>2015-02-03</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/1992Metic..27R.227G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1992Metic..27R.227G"><span>Cosmic-Ray Exposure History of Enstatite Meteorites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Graf, Th.; Marti, K.</p> <p>1992-07-01</p> <p>Enstatite achondrites display long exposure ages (T(sub)e) compared to the collisional lifetimes of ordinary chondrites of ~17 Ma (Eberhardt et al., 1965; Graf and Marti, 1992), and therefore suggest special orbits for these meteorites. Recently, Gaffey et al. (1992) suggested a link between aubrites, near- Earth asteroid 3103 and E-type asteroids of the Hungaria family, based on spectral matches and orbital considerations. This would represent the first direct link of a meteorite type and an asteroid family. Moreover, the orbital elements of Apollo object 3103 are consistent with long collisional lifetimes as observed for the Norton County and Mayo Belwa aubrites (T(sub)e = 110-120 Ma). There has been much debate over the genetic relation between E-chondrites and aubrites (Keil, 1989). Crabb and Anders (1981) found that exposure ages show a pronounced trend E4 < E6 < aubrites. We reevaluate the cosmic ray record of enstatite meteorites based on an updated database (Schultz and Kruse, 1989) as well as improved production rates and shielding corrections. We make the following observations: 1) Five out of 11 aubrites cluster at T(sub)e = 55+-5 Ma. All three known solar gas-bearing aubrites belong to this group, lending considerable support to the reality of a discrete event at this time. 2) While Gaffey et al. (1992) suggested that a significant fraction of aubrites may derive from 1-2 meteorite streams, the average ^22Ne/21Ne ratios of ~1.11 and saturated ^<span class="hlt">26</span><span class="hlt">Al</span> activities render a long 2-pi irradiation interval preceding the (short) 4- pi exposure in space unlikely. 3) In a ^38Ar/^21Ne vs ^22Ne/^21Ne diagram, the inferred spallation ratios of EH-chondrites plot systematically below the expected correlation line. However, Cl abundances in EHs are about an order of magnitude larger than those in ordinary chondrites. If significant amounts of ^36Ar produced by the reaction ^35Cl(n,gamma)^<span class="hlt">36</span><span class="hlt">Cl</span> --> ^36Ar are present, the standard procedure overestimates trapped Ar</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009EGUGA..1113207S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009EGUGA..1113207S"><span>The Lateglacial to Holocene transition as recorded by glacier fluctuations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schindelwig, I.; Akçar, N.; Kubik, P. W.; Schlüchter, C.</p> <p>2009-04-01</p> <p> European Alps. Journal of Quaternary Science, 23, 559-573. Ivy-Ochs, S., Schlüchter, C., Kubik, P. W., Synal, H.-A., Beer, J., Kerschner, H. (1996): The exposure age of an Egesen moraine at Julier Pass, Switzerland, measured with 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>. Eclogae geol. Helv., 89, 1049-1063. Kelly, M.A., Kubik, P.W., von Blanckenburg, F. & Schlüchter, C. (2004): Surface exposure dating of the Great Aletsch Glacier Egesen moraine system, western Swiss Alps, using the cosmogenic nuclide 10Be. Journal of Quarternary Science, 19, 431-441. Maisch, M. (1987): Zur Gletschergeschichte des alpinen Spätglazials: Analyse und Interpretation von Schneegrenzdaten. Geographica Helvetica, 42, 63-71. Putkonen, J. & Swanson, T. (2003): Accuracy of cosmogenic ages for moraines. Quarternary Research, 59, 255-261.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017Prama..88...21M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017Prama..88...21M"><span>Bound-state energy of double magic number plus one nucleon nuclei with relativistic mean-field approach</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mousavi, M.; Shojaei, M. R.</p> <p>2017-02-01</p> <p>In this work, we have obtained energy levels and charge radius for the β-stability line nucleus, in relativistic shell model. In this model, we considered a close shell for each nucleus containing double magic number and a single nucleon energy level. Here we have taken <span class="hlt">41</span><span class="hlt">Ca</span> with a single neutron in the 40Ca core as an illustrative example. Then we have selected the Eckart plus Hulthen potentials for interaction between the core and the single nucleon. By using parametric Nikiforov-Uvarov (PNU) method, we have calculated the energy values and wave function. Finally, we have calculated the charge radius for 17O, <span class="hlt">41</span><span class="hlt">Ca</span>, 49Ca and 57Ni. Our results are in agreement with experimental values and hence this model can be applied for similar nuclei.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/11348110','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11348110"><span>Chlorinated alkaloids in Menispermum dauricum DC: root culture.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sugimoto, Y; Babiker, H A; Saisho, T; Furumoto, T; Inanaga, S; Kato, M</p> <p>2001-05-18</p> <p>Feeding experiments using (<span class="hlt">36</span>)<span class="hlt">Cl</span> showed that Menispermum dauricum root culture produces four alkaloids containing chlorine. They included the novel alkaloids dauricumine and dauricumidine as well as the known alkaloids acutumine and acutumidine. The structures of novel alkaloids were established by spectroscopic, crystallographic, and chemical methods. These four alkaloids were labeled with (<span class="hlt">36</span>)<span class="hlt">Cl</span>, isolated, and fed independently to root cultures. Mutual conversion between acutumine and acutumidine, and between dauricumine and dauricumidine by N-methylation and N-demethylation, was demonstrated. Moreover, dauricumine was converted to acutumine and acutumidine. Epimerization of acutumidine to dauricumidine or vice versa was not observed. These results suggest that dauricumine is the first chlorinated alkaloid formed in cultured M. dauricum roots. Skewed distribution of radioactivity derived from labeled dauricumine is proof that epimerization at C-1 proceeds at a lower rate than N-demethylation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/15388109','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15388109"><span>Radioactive iodine waste treatment using electrodialysis with an anion exchange paper membrane.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Inoue, Hiroyoshi; Kagoshima, Mayumi; Yamasaki, Mariko; Honda, Yoko</p> <p>2004-12-01</p> <p>In order to simply and safely treat radioactive iodine waste, a study of the removal of iodide ion from radioactive waste using electrodialysis with an anion exchange paper membrane, in which trimethylhydroxylpropylammonium groups were homogeneously dispersed with high density. In Na125I and Na<span class="hlt">36</span><span class="hlt">Cl</span> concentration-cell system, electric ion and water conductances, phenomenological coefficients, have been experimentally determined on basis of nonequilibrium thermodynamics. Prepared paper membrane had higher permselectivity of 125I ion than <span class="hlt">36</span><span class="hlt">Cl</span> ions by approximately 21%. On the other hand, water flux that was accompanied by an ionic transference in prepared paper membrane was greatly larger than that in typical synthesized membrane. It is suggested that a depression of water mobility is important to practice an ideal radioactive iodide waste electrodialysis system with a novel anion exchange paper membrane.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/11295258','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11295258"><span>Aluminum bioavailability from drinking water is very low and is not appreciably influenced by stomach contents or water hardness.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Yokel, R A; Rhineheimer, S S; Brauer, R D; Sharma, P; Elmore, D; McNamara, P J</p> <p>2001-03-21</p> <p>The objectives were to estimate aluminum (Al) oral bioavailability under conditions that model its consumption in drinking water, and to test the hypotheses that stomach contents and co-administration of the major components of hard water affect Al absorption. Rats received intragastric <span class="hlt">26</span><span class="hlt">Al</span> in the absence and presence of food in the stomach and with or without concomitant calcium (Ca) and magnesium (Mg) at concentrations found in hard drinking water. The use of <span class="hlt">26</span><span class="hlt">Al</span> enables the study of Al pharmacokinetics at physiological Al concentrations without interference from 27Al in the environment or the subject. 27Al was intravenously administered throughout the study. Repeated blood withdrawal enabled determination of oral <span class="hlt">26</span><span class="hlt">Al</span> bioavailability from the area under its serum concentrationxtime curve compared to serum 27Al concentration in relation to its infusion rate. Oral Al bioavailability averaged 0.28%. The presence of food in the stomach and Ca and Mg in the water that contained the orally dosed <span class="hlt">26</span><span class="hlt">Al</span> appeared to delay but not significantly alter the extent of <span class="hlt">26</span><span class="hlt">Al</span> absorption. The present and published results suggest oral bioavailability of Al from drinking water is very low, about 0.3%. The present results suggest it is independent of stomach contents and water hardness.</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>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> </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/1990NIMPB..52..489S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1990NIMPB..52..489S"><span>Bomb chlorine-36 analysis in the characterization of unsaturated flow at a proposed radioactive waste disposal facility, Chihuahuan Desert, Texas</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Scanlon, B. R.; Kubik, P. W.; Sharma, P.; Richter, B. C.; Gove, H. E.</p> <p>1990-12-01</p> <p>The distribution of anthropogenic chlorine-36 in the unsaturated zone is used to estimate the moisture flux at a study site in the Chihuahuan Desert, Texas, for a potential low-level radioactive waste disposal facility. The unsaturated zone at the study site is approximately 150 m thick; the uppermost section consists of 15 m of coarse-grained sediment that overlies 140 m of clay. The {<span class="hlt">36</span><span class="hlt">Cl</span>}/{Cl} depth profile includes a well-defined peak ratio of 6.6×10 -12 at a depth of 0.5 m. A background {<span class="hlt">36</span><span class="hlt">Cl</span>}/{Cl} ratio of 0.46 × 10 -12 below a depth of 1.25 m agrees with the predicted natural fallout of 0.50×10 -12 for this latitude. The measured total inventory of bomb <span class="hlt">36</span><span class="hlt">Cl</span> is 2.5 × 10 -12 atoms m -2, which is 73% of the predicted fallout at this latitude. The specific moisture flux based on the {<span class="hlt">36</span><span class="hlt">Cl</span>}/{Cl} peak depth is 1.4 mm a -1, or 0.5% of the mean annual precipitation rate in the region. Because the bomb pulse is restricted to the root zone, it is not possible to determine if this infiltrating water will recharge the deep water table. The movement of liquid and vapor phases of water in the shallow, unsaturated zone is complex and includes both downward- and upward-directed flux components controlled by infiltration and evapotranspiration; therefore, Cl data that delineate the net movement of water over a long time period are critical in evaluation of the potential for radionuchde transport from disposal facilities.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6168944','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6168944"><span>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://pubs.er.usgs.gov/publication/70073667','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70073667"><span>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('http://www.osti.gov/scitech/servlets/purl/137509','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/137509"><span>Study plan for water movement test: Site Characterization Plan Study 8.3.1.2.2.2</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Norris, A.E.</p> <p>1989-09-01</p> <p>The water movement tracer test is designed to produce information derived from isotopic measurements of soil and tuff samples collected from Yucca Mountain that is pertinent for assessing the performance of a nuclear waste repository. Measurements of chlorine isotropic distributions will help characterize the percolation of precipitation into the unsaturated zone. The {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> in the unsaturated zone occurs from atmospheric fallout of {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> produced by cosmic-ray secondaries reacting with {sup 40}Ar and, to a lesser extent, with {sup 36}Ar. It also occurs as global fallout from high-yield nuclear weapons tests conducted at the Pacific Proving Grounds between 1952 and 1962. When chloride ions at the surface are washed underground by precipitation, the radioactive decay of the {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> in the chloride can be used to time the rate of water movement. The {sup 36}l half-life of 301,000 yr permits the detection of water movement in the range of approximately 50,000 to 2 million years. These data are part of the input for developing numerical models of ground water flow at this site. 5 refs., 4 figs., 4 tabs.</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>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/4084790','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/4084790"><span>Furosemide- and bumetanide-sensitive ion transport and volume control in primary astrocyte cultures 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>Kimelberg, H K; Frangakis, M V</p> <p>1985-12-30</p> <p>K+ and Cl- transport using 42K+ and <span class="hlt">36</span><span class="hlt">Cl</span>- was studied in primary astrocyte cultures prepared from neonatal rat brains. A component of 42K+ uptake was sensitive to both furosemide and bumetanide with maximum inhibition being obtained at 1 and 0.01 mM concentrations of the inhibitors, respectively. Furosemide and bumetanide also markedly inhibited uptake of <span class="hlt">36</span><span class="hlt">Cl</span>-. 42K+ uptake in the presence of ouabain was also sensitive to the omission of medium Na+ and Cl-. These results suggest the existence of a K+ + Na+ + Cl- cotransport system in astrocyte cultures which in many cells has been shown to be involved in volume regulation. We studied volume changes using uptake of [14C]3-O- methyl-D-glucose ([14C]3-OMG), and also ion transport, in attached cells in response to exposure to hyper- or hypotonic medium. Exposure to medium made hypertonic with mannitol resulted in shrinkage of the [14C]3-OMG space of the cells, but did not affect <span class="hlt">36</span><span class="hlt">Cl</span>- content, expressed as nmol/mg protein. Exposure to hypotonic medium led to a marked increase in the [14C]3-OMG space, rapidly followed by a decrease towards control values. After the cells were then exposed to isotonic medium there was an immediate decrease followed by a slower increase in the [14C]3-OMG space. The increase in the [14C]3-OMG space was partially inhibited by 1 mM furosemide.(ABSTRACT TRUNCATED AT 250 WORDS)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5876125','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5876125"><span>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('https://www.osti.gov/scitech/biblio/7024378','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/7024378"><span>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/2017MNRAS.tmp..140P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017MNRAS.tmp..140P"><span>A Deep Mixing Solution to the Aluminum and Oxygen Isotope Puzzles in Presolar Grains</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Palmerini, S.; Trippella, O.; Busso, M.</p> <p>2017-01-01</p> <p>We present here the application of a model for a mass circulation mechanism in between the H-burning shell and the base of the convective envelope of low mass AGB stars, aimed at studying the isotopic composition of those presolar grains showing the most extreme levels of 18O depletion and high concentration of 26Mg from the decay of <span class="hlt">26</span><span class="hlt">Al</span>. The mixing scheme we present is based on a previously suggested magnetic-buoyancy process, already shown to account adequately for the formation of the main neutron source for slow neutron captures in AGB stars. We find that this scenario is also capable of reproducing for the first time the extreme values of the {^{17}O/^{16}O}, the {^{18}O/^{16}O}, and the {^{<span class="hlt">26</span>}<span class="hlt">Al</span>/^{27}Al} isotopic ratios found in the mentioned oxide grains, including the highest amounts of <span class="hlt">26</span><span class="hlt">Al</span> there measured.</p> </li> <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>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('http://adsabs.harvard.edu/abs/2015NIMPB.361..281J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015NIMPB.361..281J"><span>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('https://www.ncbi.nlm.nih.gov/pubmed/26858438','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26858438"><span>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('https://www.osti.gov/pages/biblio/1341542-use-aluminum-nitride-improve-aluminum-accelerator-mass-spectrometry-measurements-production-radioactive-ion-beams','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1341542-use-aluminum-nitride-improve-aluminum-accelerator-mass-spectrometry-measurements-production-radioactive-ion-beams"><span>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://www.osti.gov/pages">DOE PAGES</a></p> <p>Janzen, Meghan S.; Galindo-Uribarri, Alfredo; Liu, Yuan; ...</p> <p>2015-06-29</p> <p>In this paper, 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 andmore » 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. In conclusion, 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>.« less</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>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/1984Natur.308..169H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1984Natur.308..169H"><span>Ion microprobe magnesium isotope analysis of plagioclase and hibonite from ordinary chondrites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hinton, R. W.; Bischoff, A.</p> <p>1984-03-01</p> <p>In a search for 26Mg excesses generated by <span class="hlt">26</span><span class="hlt">Al</span> decay the authors analysed four Al-rich objects from the type 3 ordinary chondrites using an ion microprobe. They report here the presence of 26Mg excesses of up to 100% in an unusually pure hibonite clast from the Dhajala chondrite; this 26Mg excess is the first to be found in an ordinary chondrite. No 26Mg excesses were observed in the three plagioclase-bearing chondrules analysed. It is concluded that <span class="hlt">26</span><span class="hlt">Al</span> may not have been sufficiently plentiful to act as a major heat source in condensed Solar System bodies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6043691','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6043691"><span>Effects of silicon on gastrointestinal absorption of aluminium</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Edwardson, J.A.; Moore, P.B.; Ferrier, I.N.; Lilley, J.S.; Newton, G.W.A.; Barker, J.; Templar, J.; Day, J.P.</p> <p>1993-07-24</p> <p>The reported geographical association between Alzheimer's disease and levels of aluminium (Al) in water supplies may reflect the inverse relation between Al and silicon (Si) concentrations in water, and the potential for Si to reduce the bioavailability of the metal. The authors tested this hypothesis using isotopic [sup <span class="hlt">26</span>]<span class="hlt">Al</span> tracer administered orally to five healthy volunteers in the presence and absence of Si. Dissolved Si, at a concentration found in some water supplies reduced the peak plasma [sup <span class="hlt">26</span>]<span class="hlt">Al</span> concentration to 15% of the value obtained in the absence of Si. The results indicate that dissolved Si is an important factor in limiting the absorption of dietary Al.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.5149A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.5149A"><span>Cosmogenic nuclide dating of glaciofluvial deposits: insights 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>Akcar, Naki; Ivy-Ochs, Susan; Alfimov, Vasily; Claude, Anne; Reber, Regina; Christl, Marcus; Vockenhuber, Christof; Schlunegger, Fritz; Rahn, Meinert; Dehnert, Andreas; Schlüchter, Christian</p> <p>2015-04-01</p> <p>Cosmogenic 10Be and <span class="hlt">26</span><span class="hlt">Al</span> can be employed to reconstruct the chronology of sediment layers. Accumulation of these can be used to exposure date the sediment layer as the variation of cosmogenic nuclide concentration with depth can be modeled. Decay of 10Be and <span class="hlt">26</span><span class="hlt">Al</span> in the samples from a well-defined single bed in a deposit 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 depth-profile and 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 studied two Deckenschotter outcrops in abandoned gravel pits in Mandach (507 m a.s.l.) and Siglistorf (530 m a.s.l.) in canton Zurich. We collected four samples from Mandach for 10Be analysis and more than 30 clasts of different lithology, shape and size from a single stratigraphic horizon in Siglistorf among which we processed 19 clasts for 10Be and <span class="hlt">26</span><span class="hlt">Al</span> analysis. 10Be concentrations of the Mandach samples vary between 10000 and 30000 at/g. Based on these, we calculated a modal depth-profile age of around 1.0 Ma. Among Siglistorf samples, four 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. The <span class="hlt">26</span><span class="hlt">Al</span>/10Be ratio of eight samples was above the surface ratio of 6</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011LPI....42.1147W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011LPI....42.1147W"><span>Extremely Na and Cl Rich Chondrule Al3509 from the Allende Meteorite</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wasserburg, G. J.; Hutcheon, I. D.; Aleon, J.; Ramon, E. C.; Krot, A. N.; Nagashima, K.; Brearley, A. J.</p> <p>2011-03-01</p> <p>This Ca-Al-rich chondrule is not a replacement product. It has ~10% Na and ~1% Cl. Large excesses of 36S were found uncorrelated with Cl and <span class="hlt">26</span><span class="hlt">Al</span>/27Al < 3 x 10^-6. It represents the fluid responsible for late alteration in volatile-rich outer layers prior to formation of Allende.</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>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/2017GeCoA.196...18N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017GeCoA.196...18N"><span>Corundum-hibonite inclusions and the environments of high temperature processing 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>Needham, Andrew W.; Messenger, Scott; Han, Jangmi; Keller, Lindsay P.</p> <p>2017-01-01</p> <p>Corundum-bearing Ca-Al-rich inclusions (CAIs) are a rare class of high-temperature condensates from the inner regions of the protoplanetary disk. Their mineralogy is intermediate between isolated corundum grains and CAIs where corundum has been replaced by lower-temperature phases. These inclusions sample a critical transitional period of the inner nebula where both the Sun and protoplanetary disk were rapidly evolving. We conducted O isotopic, Al-Mg chronological, petrographic, and crystallographic studies of four corundum-bearing inclusions in the Murchison CM2 and ALHA 77307 CO3.0 carbonaceous chondrites. Within each inclusion, corundum, hibonite, and spinel have indistinguishable 16O-rich compositions. The O isotopic compositions from all inclusions fall within a narrow range of Δ17O = -22.8 ± 3.6‰ that matches values of most previously studied micrometer-sized corundum grains and mineralogically pristine CAIs. These data indicate that, with few exceptions, the most refractory inclusions in carbonaceous chondrites formed from the same O isotopic reservoir. One CAI from ALHA 77307, ALH-61, exhibits a continuous corundum mantle overlying a hibonite core, opposite the equilibrium condensation sequence at typical nebular pressures and dust/gas ratios. Transmission electron microscopy examination of the hibonite-corundum interface suggests that the corundum condensed on the hibonite and was itself then partially overlain with spinel. Additionally, high dust/gas ratios are interpreted from the W- and Mo-depleted composition of a refractory metal nugget within a second corundum-bearing CAI, ALH-160. Together, these observations show that the primary formation conditions of some corundum-bearing CAIs involved non-equilibrium condensation in environments with elevated dust-gas ratios. The corundum-bearing CAIs studied here have inferred initial <span class="hlt">26</span><span class="hlt">Al</span>/27Al ratios that fall within the roughly bimodal distribution of values observed in most CAIs. ALH-160 retains no</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('http://adsabs.harvard.edu/abs/2006isna.confE...1D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006isna.confE...1D"><span>Nuclear astrophysics with gamma-ray line observations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Diehl, Roland</p> <p></p> <p>Gamma-ray spectrometers with high spectral resolution have been operated in space since 2002. Major efforts to understand instrumental response and backgrounds are a requird before detailed science interpretations can be derived; by now, high-resolution line-shape studies have resulted in significant astrophysical constraints, not only through studies of solar-flare details, but also for nuclear processes in the Galaxy: 44Ti from the Cas A supernova could only be detected in the low-energy lines at 68 and 78 keV, the 1157 keV line from the same decay is not seen; this constrains 44Ti ejection in core collapse supernovae. Diffuse nucleosynthesis is studied through <span class="hlt">26</span> <span class="hlt">Al</span>, 60Fe, and positron annihilation gamma-ray measurements. The gamma-ray line from decay of radioactive <span class="hlt">26</span><span class="hlt">Al</span> could be measured at unpredecented spectroscopic precision. The new determination of the total mass of <span class="hlt">26</span><span class="hlt">Al</span> produced by stellar sources throughout the Galaxy yields 2.8 ±0.9 M , and the interstellar medium around <span class="hlt">26</span><span class="hlt">Al</span> sources appears characterized by velocities in the ~100 km s-1 region. 60Fe is clearly detected with SPI, its intensity ratio to <span class="hlt">26</span><span class="hlt">Al</span> of ~15% is on the lower side of predictions from massive-star and supernova nucleosynthesis models. Nucleosynthesis sources are probably minor contributors to Galactic positrons; this may be deduced from the bulge-centered spatial distribution of the annihilation gamma-ray emission, considering that nucleosynthesis sources are expected to populate mainly the disk part of the Galaxy. It is evident that new views at nuclear and astrophysical processes in and around cosmic sources are being provided through these space missions.</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>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('http://adsabs.harvard.edu/abs/2016Geomo.273..412C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016Geomo.273..412C"><span>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://pubs.er.usgs.gov/publication/70185577','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70185577"><span>Use of multiple age tracers to estimate groundwater residence times and long-term recharge rates in arid southern Oman</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Müller, Th.; Osenbrück, K.; Strauch, G.; Pavetich, S.; Al-Mashaikhi, K.-S.; Herb, C.; Merchel, S.; Rugel, G.; Aeschbach, W.; Sanford, Ward E.</p> <p>2016-01-01</p> <p>Multiple age tracers were measured to estimate groundwater residence times in the regional aquifer system underlying southwestern Oman. This area, known as the Najd, is one of the most arid areas in the world and is planned to be the main agricultural center of the Sultanate of Oman in the near future. The three isotopic age tracers 4He, 14C and <span class="hlt">36</span><span class="hlt">Cl</span> were measured in waters collected from wells along a line that extended roughly from the Dhofar Mountains near the Arabian Sea northward 400 km into the Empty Quarter of the Arabian Peninsula. The wells sampled were mostly open to the Umm Er Radhuma confined aquifer, although, some were completed in the mostly unconfined Rus aquifer. The combined results from the three tracers indicate the age of the confined groundwater is < 40 ka in the recharge area in the Dhofar Mountains, > 100 ka in the central section north of the mountains, and up to and > one Ma in the Empty Quarter. The 14C data were used to help calibrate the 4He and <span class="hlt">36</span><span class="hlt">Cl</span> data. Mixing models suggest that long open boreholes north of the mountains compromise 14C-only interpretations there, in contrast to 4He and <span class="hlt">36</span><span class="hlt">Cl</span> calculations that are less sensitive to borehole mixing. Thus, only the latter two tracers from these more distant wells were considered reliable. In addition to the age tracers, δ2H and δ18O data suggest that seasonal monsoon and infrequent tropical cyclones are both substantial contributors to the recharge. The study highlights the advantages of using multiple chemical and isotopic data when estimating groundwater travel times and recharge rates, and differentiating recharge mechanisms.</p> </li> <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>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('https://www.osti.gov/scitech/biblio/5641405','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5641405"><span>Ultraviolet irradiation selectively disrupts the gamma-aminobutyric acid/benzodiazepine receptor-linked chloride ionophore</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Evoniuk, G.; Moody, E.J.; Skolnick, P. )</p> <p>1989-05-01</p> <p>The ability of UV light to affect radioligand binding and <span class="hlt">36</span><span class="hlt">Cl</span>-uptake at the gamma-aminobutyric acidA (GABAA) receptor-chloride channel complex was examined. Exposure to 302 nm UV light produced a rapid (t1/2 = 4 min) reduction in (35S)t-butylbicyclo-phosphorothionate binding (assayed in the presence of 200 mM chloride) to sites associated with the GABAA receptor-coupled chloride ionophore. Saturation analysis revealed that this effect could be attributed entirely to a decrease in the maximum number of binding sites. Exposure to UV irradiation at lower (254 nm) and higher (366 nm) wavelengths also inhibited (35S)t-butylbicy-clophosphorothionate binding, but the respective rates of inactivation were 8- and 27-fold slower, compared with 302 nm. Other anion-dependent interactions at the GABAA receptor complex were disrupted in a similar manner. In the absence of permeant anion, (3H)flunitrazepam binding to benzodiazepine receptors was unaffected by 302 nm UV irradiation, whereas chloride-enhanced (3H)flunitrazepam binding was inhibited markedly. In the presence of 250-500 mM chloride, (3H)methyl-6,7-dimethoxy-4-ethyl-beta-carboline-3-carboxylate binding to benzodiazepine receptors was also inhibited after UV exposure. Basal <span class="hlt">36</span><span class="hlt">Cl</span>- uptake into synaptoneurosomes was nearly doubled after 15 min of exposure to 302 nm light, whereas pentobarbital- and muscimol-stimulated <span class="hlt">36</span><span class="hlt">Cl</span>- uptake were reduced significantly. UV irradiation at 302 nm appears to disrupt selectively the anion-dependent functional interactions at the GABAA receptor complex. The apparent wavelength specificity suggests that the gating structure (channel) may contain tryptophan and/or tyrosine residues vital to the regulation of anion movement through the ionophore portion of this supramolecular receptor-ion channel complex.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5459599','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5459599"><span>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> <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>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>2014-01-15</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://adsabs.harvard.edu/abs/2002CRPhy...3..975T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002CRPhy...3..975T"><span>Confinement et migration de radionucléides dans l'environnement d'un stockage de déchets nucléaires</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Toulhoat, Pierre</p> <p>2002-10-01</p> <p>The safety of the geological disposal of nuclear waste is evaluated, among other factors, through the ability of radionuclides to be confined, first by waste packages then by engineered barriers and host rocks. Deep underground conditions favour the immobilisation of most radionuclides by sorption or precipitation, which means that mobile radionuclides, such as 129I or <span class="hlt">36</span><span class="hlt">Cl</span>, may contribute to most of the ultimate dose release during up to a million years. However, degraded evolution scenarios must be taken into account (oxygen intrusion, faults, …) to assess earlier dose releases. To cite this article: P. Toulhoat, C. R. Physique 3 (2002) 975-986.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/60270','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/60270"><span>Laboratory and field studies related to the radionuclide migration project. Progress report, October 1, 1980-September 30, 1981</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Daniels, W.R.</p> <p>1982-02-01</p> <p>FY 1981 laboratory and field studies related to the Radionuclide Migration project are described. Results are presented for radiochemical analyses of water samples collected from the RNM-1 well and the RNM-2S satellite well at the Cambric site. Data are included for tritium, {sup 85}Kr, {sup 129}I, and {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>. The maximum-concentration tritium, peak appears to have arrived at RNM-2S near the end of FY-1981. Laboratory studies emphasize the sorptive behavior of alluvium and tuff and its dependence on mineralogy. Results from batch measurements and crushed-rock and whole-core column studies are presented.</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>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('https://www.osti.gov/scitech/biblio/22069003','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22069003"><span>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('https://www.osti.gov/scitech/biblio/6172784','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6172784"><span>Effect of phosphatidylserine on the basal and GABA-activated Cl- permeation across single nerve membranes from rabbit Deiters' neurons</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Rapallino, M.V.; Cupello, A.; Mainardi, P.; Besio, G.; Loeb, C.W. )</p> <p>1990-06-01</p> <p>The permeation of labeled Cl- ions across single plasma membranes from Deiters' neurons has been studied in the presence of various concentrations of phosphatidylserine (PS) on their extracellular side. PS reduces significantly basal Cl- permeation only at 10(-5) M on the membrane exterior. No effect was found at other concentrations. GABA activable <span class="hlt">36</span><span class="hlt">Cl</span>- permeation is heavily reduced and almost abolished at 10(-11) - 10(-5) M phosphatidylserine. This exogenous phosphatidylserine effect is difficult to interpret in relation to the function of the endogenous phospholipid. However, it may be involved in the epileptogenic effect in vivo of exogenous phosphatidylserine administration to rats.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/7013312','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/7013312"><span>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('https://www.ncbi.nlm.nih.gov/pubmed/22436448','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22436448"><span>Numerical modeling of large-area beta sources constructed from anodized-aluminum foils.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Stanga, D</p> <p>2012-09-01</p> <p>The numerical modeling of large-area beta sources constructed from anodized-aluminum foils is described in this paper. Based on a realistic model for the activity depth distribution, theoretical lower and upper bounds for the efficiency and the transmission coefficient were calculated and used to analyze the comparison method recommended by ISO 8769 for measuring the surface emission rate. The analysis shows that this method can provide measurement results with relative standard uncertainties smaller than 3% for high energy beta emitters such as (90)Sr-(90)Y, (<span class="hlt">36</span>)<span class="hlt">Cl</span> and (204)Tl.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70186233','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70186233"><span>Chlorine-36 in the Snake River Plain Aquifer at the Idaho National Engineering Laboratory; origin and implications</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Beasley, T.M.; Cecil, L.D.; Sharma, P.; Kubik, P.W.; Fehn, U.; Mann, L.J.; Gove, H.E.</p> <p>1993-01-01</p> <p>Between 1952 and 1984, low-level radioactive waste was introduced directly into the Snake River Plain aquifer at the Idaho National Engineering Laboratory (INEL), Idaho Falls, Idaho. These wastes were generated, principally, at the nuclear fuel reprocessing facility on the site. Our measurements of 36C1 in monitoring and production well waters, downgradient from disposal wells and seepage ponds, found easily detectable, nonhazardous concentrations of this radionuclide from the point of injection to the INEL southern site boundary. Comparisons are made between 3H and <span class="hlt">36</span><span class="hlt">Cl</span> concentrations in aquifer water and the advantages of 36C1 as a tracer of subsurface-water dynamics at the site are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/924364','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/924364"><span>The Synthesis of Transition Metal Nitrides via Thermolysis of Metal-ammine Complexes, Part 1: Chromium Nitride</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Weil, K Scott</p> <p>2008-01-01</p> <p>The thermal decomposition of a CrN precursor, hexaammine chromium (II) chloride, in helium and ammonia has been investigated via a combination of thermogravimmetric analysis, differential thermal analysis, Fourier transform infared spectroscopy, and X-ray diffraction. Upon heating [Cr(NH3)6]Cl2 sequentially loses ammonia ligands, ultimately forming CrCl2•NH3 at ~400ºC. In helium, this intermediate undergoes thermolysis to form a rock-salt structured, sub-stoichiometric chromium nitride, whereas in ammonia it ammonolyzes to form CrN.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6152528','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6152528"><span>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('http://adsabs.harvard.edu/abs/2014E%26PSL.390..318M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014E%26PSL.390..318M"><span>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>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> </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('https://ntrs.nasa.gov/search.jsp?R=19860042318&hterms=particle+accelerator&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dparticle%2Baccelerator','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19860042318&hterms=particle+accelerator&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dparticle%2Baccelerator"><span>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/2016NIMPB.377...37J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016NIMPB.377...37J"><span>Measurement of deuteron induced gamma-ray emission differential cross sections on natCl from 1.0 to 2.0 MeV</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jokar, A.; Kakuee, O.; Lamehi-Rachti, M.</p> <p>2016-06-01</p> <p>In this research work, measured differential cross sections for gamma-ray emission from the nuclear reactions 35Cl(d,pγ1-0)<span class="hlt">36</span><span class="hlt">Cl</span> (Eγ = 788 keV), 35Cl(d,pγ2-0)<span class="hlt">36</span><span class="hlt">Cl</span> (Eγ = 1165 keV), 37Cl(d,pγ1-0)38Cl (Eγ = 671 keV) and 37Cl(d,pγ2-0)38Cl (Eγ = 755 keV) are presented. For these measurements a thin natural BaCl2 target evaporated onto a 50 μm-thick Mo foil was used. The gamma-rays and backscattered deuterons were detected simultaneously. An HPGe detector placed at an angle of 90° with respect to the beam direction was employed to collect gamma-rays while an ion implanted Si detector placed at a scattering angle of 165° was used to detect backscattered deuterons. The validity of the obtained differential cross sections was verified through a thick target benchmarking experiment. The overall systematic uncertainty of cross section values was estimated to be ±10%.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28322311','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28322311"><span>Orogen-scale uplift in the central Italian Apennines drives episodic behaviour of earthquake faults.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cowie, P A; Phillips, R J; Roberts, G P; McCaffrey, K; Zijerveld, L J J; Gregory, L C; Faure Walker, J; Wedmore, L N J; Dunai, T J; Binnie, S A; Freeman, S P H T; Wilcken, K; Shanks, R P; Huismans, R S; Papanikolaou, I; Michetti, A M; Wilkinson, M</p> <p>2017-03-21</p> <p>Many areas of the Earth's crust deform by distributed extensional faulting and complex fault interactions are often observed. Geodetic data generally indicate a simpler picture of continuum deformation over decades but relating this behaviour to earthquake occurrence over centuries, given numerous potentially active faults, remains a global problem in hazard assessment. We address this challenge for an array of seismogenic faults in the central Italian Apennines, where crustal extension and devastating earthquakes occur in response to regional surface uplift. We constrain fault slip-rates since ~18 ka using variations in cosmogenic (<span class="hlt">36</span>)<span class="hlt">Cl</span> measured on bedrock scarps, mapped using LiDAR and ground penetrating radar, and compare these rates to those inferred from geodesy. The (<span class="hlt">36</span>)<span class="hlt">Cl</span> data reveal that individual faults typically accumulate meters of displacement relatively rapidly over several thousand years, separated by similar length time intervals when slip-rates are much lower, and activity shifts between faults across strike. Our rates agree with continuum deformation rates when averaged over long spatial or temporal scales (10(4) yr; 10(2) km) but over shorter timescales most of the deformation may be accommodated by <30% of the across-strike fault array. We attribute the shifts in activity to temporal variations in the mechanical work of faulting.</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>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/servlets/purl/6268046','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/6268046"><span>Chemical and isotopic characteristics of thermal fluids in the Long Valley caldera lateral flow system, California</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Shevenell, L.; Goff, F.; Grigsby, C.O.; Janik, C.J.; Trujillo, P.E. Jr.; Counce, D.</p> <p>1987-01-01</p> <p>Chemical and isotopic data of thermal waters in Long Valley caldera have been used to identify both the origins and characteristics of the fluids and to evaluate mixing and boiling processes occurring within the lateral flow system of the caldera. Recharge to the Long Valley geothermal system occurs in the western part of the caldera with the water being heated at depth and flowing laterally eastward in the subsurface. The lateral flow system was recently intersected by the Shady Rest Continental Scientific Drilling Program (CSDP) corehole at 335 m (1100 ft) with fluids in this 202/sup 0/C zone being more concentrated than non-boiled fluids to the east. As the Na-K-HCO/sub 3/-Cl thermal fluids flow eastward, they are increasingly mixed with isotopically depleted, dilute groundwaters similar to cold waters east of Lake Crowley. Near surface boiling of Casa Diablo well fluids at 100/sup 0/C forms waters with the compositions of Colton and Casa Diablo hot springs. Waters to the east of the Casa Diablo area are mixtures of meteoric water and boiled thermal fluids with a composition close to that of Colton Hot Spring. There is no correlation between /sup 3/H and /sup <span class="hlt">36</span>/<span class="hlt">Cl</span> in thermal fluids or between these components and conservative species, and it appears that cold fluids involved in mixing must be relatively old waters, low in both meteoric /sup 3/H and /sup <span class="hlt">36</span>/<span class="hlt">Cl</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003WRR....39.1182Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003WRR....39.1182Z"><span>Late Pleistocene and Holocene groundwater recharge from the chloride mass balance method and chlorine-36 data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhu, Chen; Winterle, James R.; Love, Erica I.</p> <p>2003-07-01</p> <p>The chloride mass balance (CMB) method for estimating groundwater recharge is economic and effective, provided that the hydrological conditions for its applications are met and the modeling parameters are known. However, modeling parameters such as precipitation and Cl- deposition rates vary temporally, most notably as a result of the climatic changes from late Pleistocene to Holocene. The temporal variability of atmospheric Cl- input and annual precipitation were considered in this study by using a discrete steady state CMB model with different parameters for late Pleistocene and Holocene. Cl- deposition rates, estimated from <span class="hlt">36</span><span class="hlt">Cl</span> data, were lower in late Pleistocene than Holocene at Yucca Mountain, Nevada, but higher in late Pleistocene than Holocene at Black Mesa, Arizona. Paleoclimate proxies at both Yucca Mountain and Black Mesa point to higher precipitation rates in late Pleistocene than Holocene. The resulting average recharge estimates for Black Mesa are 9 ± 5 mm/yr for Holocene and 35 ± 22 mm/yr for late Pleistocene. Local recharge rates at Yucca Mountain were estimated from the <span class="hlt">36</span><span class="hlt">Cl</span>/Cl ratios and Cl- concentrations in perched waters. The estimated recharge for Yucca Mountain is 5 ± 1 mm/yr for Holocene and 15 ± 5 mm/yr for late Pleistocene. These recharge rates are comparable to results of independent numerical groundwater flow models and watershed-scale infiltration models at Black Mesa and Yucca Mountain, respectively.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017QSRv..162..111P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017QSRv..162..111P"><span>Deglaciation in the central Pyrenees during the Pleistocene-Holocene transition: Timing and geomorphological significance</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Palacios, David; García-Ruiz, José M.; Andrés, Nuria; Schimmelpfennig, Irene; Campos, Néstor; Léanni, Laëtitia; Aumaître, Georges; Bourlès, Didier L.; Keddadouche, Karim</p> <p>2017-04-01</p> <p>In this study, we document deglaciation in a sector of the southern-central Pyrenees (the Panticosa massif and the upper Gállego and Ossau valleys) using cosmic-ray exposure (CRE) dating methods, which were applied to samples from high altitude polished rock steps and rock glacier boulders. The obtained CRE dates show a coherent spatial distribution and confirm results previously obtained in this study area, thus demonstrating the reliability and robustness of the method. The results of analyses based on two distinct isotopes (10Be and <span class="hlt">36</span><span class="hlt">Cl</span>) are consistent, although the error is higher for results based on the <span class="hlt">36</span><span class="hlt">Cl</span> isotope. The study provides evidence for ice extent in the High Gállego Valley during the Oldest Dryas, with glacial advance until the bottom of the valleys, although the main glacier tongues remained disconnected from each other. During this period, the extent of glacier advance was directly related to the elevation of the associated summits. The Younger Dryas glaciers were constrained to cirques or very short ice tongues, and dating of the polished rock steps indicates that the ice masses were present until the first millennium of the Holocene. The Brazato rock glacier developed at the beginning of the Holocene and remained active until the Holocene Thermal Optimum, because of the protective effect of large masses of blocks and boulders.</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>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('http://adsabs.harvard.edu/abs/2015JHyd..523..624S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JHyd..523..624S"><span>Recent and old groundwater in the Niebla-Posadas regional aquifer (southern Spain): Implications for its management</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Scheiber, Laura; Ayora, Carlos; Vázquez-Suñé, Enric; Cendón, Dioni I.; Soler, Albert; Custodio, Emilio; Baquero, Juan Carlos</p> <p>2015-04-01</p> <p>The Niebla-Posadas (NP) aquifer in southern Spain is one of the main groundwater sources for the lower Guadalquivir Valley, a semiarid region supporting an important population, agriculture and industry. To contribute to the understanding of this aquifer the assessment of sustainable use of groundwater, the residence time of groundwater in the NP aquifer has been estimated using 3H, 14C and <span class="hlt">36</span><span class="hlt">Cl</span>. Along the flow paths, recharged groundwater mixes with NaCl-type waters and undergoes calcite dissolution and is further modified by cation exchange (Ca-Na). Consequently, the water loses most of its calcium and the residual δ13CDIC in the groundwater is isotopically enriched. Further modifications take place along the flow path in deeper zones, where depleted δ13CDIC values are overprinted due to SO42- and iron oxide reduction, triggered by the presence of organic matter. Dating with 3H, 14C and <span class="hlt">36</span><span class="hlt">Cl</span> has allowed the differentiation of several zones: recharge zone (<0.06 ky), intermediate zone (0.06-20 ky), deep zone 1 (20-30 ky), and deep zone 2 (>30 ky). An apparent link between the tectonic structure and the groundwater residence time zonation can be established. Regional faults clearly separates deep zone 1 from the distinctly older age (>30 ky) deep zone 2. From the estimated residence times, two groundwater areas of different behavior can be differentiated within the aquifer.</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>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://adsabs.harvard.edu/abs/2017NatSR...744858C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017NatSR...744858C"><span>Orogen-scale uplift in the central Italian Apennines drives episodic behaviour of earthquake faults</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cowie, P. A.; Phillips, R. J.; Roberts, G. P.; McCaffrey, K.; Zijerveld, L. J. J.; Gregory, L. C.; Faure Walker, J.; Wedmore, L. N. J.; Dunai, T. J.; Binnie, S. A.; Freeman, S. P. H. T.; Wilcken, K.; Shanks, R. P.; Huismans, R. S.; Papanikolaou, I.; Michetti, A. M.; Wilkinson, M.</p> <p>2017-03-01</p> <p>Many areas of the Earth’s crust deform by distributed extensional faulting and complex fault interactions are often observed. Geodetic data generally indicate a simpler picture of continuum deformation over decades but relating this behaviour to earthquake occurrence over centuries, given numerous potentially active faults, remains a global problem in hazard assessment. We address this challenge for an array of seismogenic faults in the central Italian Apennines, where crustal extension and devastating earthquakes occur in response to regional surface uplift. We constrain fault slip-rates since ~18 ka using variations in cosmogenic <span class="hlt">36</span><span class="hlt">Cl</span> measured on bedrock scarps, mapped using LiDAR and ground penetrating radar, and compare these rates to those inferred from geodesy. The <span class="hlt">36</span><span class="hlt">Cl</span> data reveal that individual faults typically accumulate meters of displacement relatively rapidly over several thousand years, separated by similar length time intervals when slip-rates are much lower, and activity shifts between faults across strike. Our rates agree with continuum deformation rates when averaged over long spatial or temporal scales (104 yr 102 km) but over shorter timescales most of the deformation may be accommodated by <30% of the across-strike fault array. We attribute the shifts in activity to temporal variations in the mechanical work of faulting.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5264541','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5264541"><span>cAMP and forskolin decrease. gamma. -aminobutyric acid-gated chloride flux in rat brain synaptoneurosomes</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Heuschneider, G.; Schwartz, R.D. )</p> <p>1989-04-01</p> <p>The effects of the cyclic nucleotide cAMP on {gamma}-aminobutyric acid-gated chloride channel function were investigated. The membrane-permeant cAMP analog N{sup 6}, O{sup 2{prime}}-dibutyryladenosine 3{prime},5{prime}-cyclic monophosphate inhibited muscimol-induced {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>{sup {minus}} uptake into rat cerebral cortical synaptoneurosomes in a concentration-dependent manner. The inhibition was due to a decrease in the maximal effect of muscimol, with no change in potency. Similar effects were observed with 8-(4-chlorophenylthio)adenosine 3{prime},5{prime}-cyclic monophosphate, 8-bromoadenosine 3{prime},5{prime}-cyclic monophosphate, and the phosphodiesterase inhibitor isobutylmethylxanthine. The effect of endogenous cAMP accumulation on the {gamma}-aminobutyric acid-gated Cl{sup {minus}} channel was studied with forskolin, an activator of adenylate cyclase. Under identical conditions, in the intact synaptoneurosomes, forskolin inhibited muscimol-induced {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>{sup {minus}} uptake and generated cAMP with similar potencies. Surprisingly, 1,9-dideoxyforskolin, which does not activate adenylate cyclase, also inhibited the muscimol response, suggesting that forskolin and its lipophilic derivatives may interact with the Cl{sup {minus}} channel directly. The data suggest that {gamma}-aminobutyric acid (GABA{sub A}) receptor function in brain can be regulated by cAMP-dependent phosphorylation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5359594','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5359594"><span>Orogen-scale uplift in the central Italian Apennines drives episodic behaviour of earthquake faults</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Cowie, P. A.; Phillips, R. J.; Roberts, G. P.; McCaffrey, K.; Zijerveld, L. J. J.; Gregory, L. C.; Faure Walker, J.; Wedmore, L. N. J.; Dunai, T. J.; Binnie, S. A.; Freeman, S. P. H. T.; Wilcken, K.; Shanks, R. P.; Huismans, R. S.; Papanikolaou, I.; Michetti, A. M.; Wilkinson, M.</p> <p>2017-01-01</p> <p>Many areas of the Earth’s crust deform by distributed extensional faulting and complex fault interactions are often observed. Geodetic data generally indicate a simpler picture of continuum deformation over decades but relating this behaviour to earthquake occurrence over centuries, given numerous potentially active faults, remains a global problem in hazard assessment. We address this challenge for an array of seismogenic faults in the central Italian Apennines, where crustal extension and devastating earthquakes occur in response to regional surface uplift. We constrain fault slip-rates since ~18 ka using variations in cosmogenic <span class="hlt">36</span><span class="hlt">Cl</span> measured on bedrock scarps, mapped using LiDAR and ground penetrating radar, and compare these rates to those inferred from geodesy. The <span class="hlt">36</span><span class="hlt">Cl</span> data reveal that individual faults typically accumulate meters of displacement relatively rapidly over several thousand years, separated by similar length time intervals when slip-rates are much lower, and activity shifts between faults across strike. Our rates agree with continuum deformation rates when averaged over long spatial or temporal scales (104 yr; 102 km) but over shorter timescales most of the deformation may be accommodated by <30% of the across-strike fault array. We attribute the shifts in activity to temporal variations in the mechanical work of faulting. PMID:28322311</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17916938','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17916938"><span>Anticarcinogenic effects of hexaamminecobalt(III) chloride in mice initiated with diethylnitrosamine.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Naura, Amarjit S; Kalla, Natwar R; Sharma, Raj P; Sharma, Rajeshwar</p> <p>2007-11-01</p> <p>Hexaamminecobalt(III) chloride ([Co(NH3)6]Cl3) was investigated for its antineoplastic role in relation to tumor marker enzymes, drug metabolizing enzymes, oxidative stress-related parameters, and histopathological analysis of liver and lung tissues of mice. Initiation was performed using a single intraperitoneal injection of diethylnitrosamine (DENA) at a carcinogenic dose of 90 mg/kg body weight. The cobalt complex supplementation at a dose of 100 ppm in drinking water was given ad libitum throughout the experimental period of 14 weeks. In comparison to lung, the cobalt complex supplementation was found to reverse DENA-induced biochemical changes more effectively in liver. Histological examination of liver and lung from DENA-initiated and cobalt-complex-supplemented mice showed considerable protection in the case of liver compared to that of lung. The involvement of the [Co(NH3)6]Cl3 in modulating several factors associated with carcinogenesis induced by DENA thus showed its anticarcinogenic potential against chemically induced hepatocarcinogenesis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003QuRes..59..213M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003QuRes..59..213M"><span>Paleomagnetic correlations between scandinavian ice-sheet fluctuations and greenland dansgaard-oeschger events, 45,000-25,000 yr B.P.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mangerud, Jan; Løvlie, Reidar; Gulliksen, Steinar; Hufthammer, Anne-Karin; Larsen, Eiliv; Valen, Vidar</p> <p>2003-03-01</p> <p>Two paleomagnetic excursions, the Skjong correlated with the Laschamp (about 41,000 GISP2 yr B.P.) and the Valderhaug correlated with the Mono Lake (about 34,000 GISP2 yr B.P.), have been identified in stratigraphic superposition in laminated clay deposited in ice-dammed lakes in three large caves in western Norway. During both periods the margin of the Scandinavian Ice Sheet advanced and reached the continental shelf beyond the outermost coastline. The mild, 4000-yr-long Ålesund interstade, when the coast and probably much of the hinterland were ice-free, separated the two glacial advances. The two paleomagnetic excursions have also been indirectly identified as increased fluxes of <span class="hlt">36</span><span class="hlt">Cl</span> and 10Be in the GRIP ice core, Greenland. This article presents a correlation between ice-margin fluctuations of the Scandinavian Ice Sheet and the stratigraphy of GRIP/GISP cores, using the paleomagnetic excursions and the <span class="hlt">36</span><span class="hlt">Cl</span> and 10Be peaks and thus circumventing the application of different dates or time scales. Some of the fluctuations of the Scandinavian Ice Sheet were of the "Allerød/Younger Dryas type" in the sense that its margin retreated during mild interstades on Greenland and readvanced during cold stades. However, some fluctuations were apparently not in phase with the Greenland climate.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/350841','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/350841"><span>Distribution of fast hydrologic paths in the unsaturated zone at Yucca Mountain</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Fabryka-Martin, J.T.; Wolfsberg, A.V.; Levy, S.S.; Roach, J.L.; Winters, S.T.; Wolfsberg, L.E.; Elmore, D.; Sharma, P.</p> <p>1998-12-31</p> <p>Development and testing of conceptual flow and transport models for hydrologic systems are strengthened when natural environmental tracers are incorporated into the process. One such tracer is chlorine-36 ({sup <span class="hlt">36</span>}<span class="hlt">Cl</span>, half-life, 301,000 years), a radioactive isotope produced in the atmosphere and carried underground with percolating groundwater. High concentrations of this isotope were also added to meteoric water during a period of global fallout from atmospheric testing of nuclear devices, primarily in the 1950s. This bomb-pulse signal has been used to test for the presence of fast transport paths in the unsaturated zone at Yucca Mountain and to provide the basis for a conceptual model for their distribution. Yucca Mountain is under investigation by the US Department of Energy as a potential site at which to host an underground high-level radioactive waste repository. Under wetter climatic conditions, fast-flow pathways will respond quickly to increases in infiltration and have the potential to become seeps in the tunnel drifts. The {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> data are also being used in numerical flow and transport models to establish lower bounds on infiltra