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Sample records for 36cl ams measurements

  1. Intercomparison study on (152)Eu gamma ray and (36)Cl AMS measurements for development of the new Hiroshima-Nagasaki Atomic Bomb Dosimetry System 2002 (DS02).

    PubMed

    Hoshi, M; Endo, S; Tanaka, K; Ishikawa, M; Straume, T; Komura, K; Rühm, W; Nolte, E; Huber, T; Nagashima, Y; Seki, R; Sasa, K; Sueki, K; Fukushima, H; Egbert, S D; Imanaka, T

    2008-07-01

    In the process of developing a new dosimetry system for atomic bomb survivors in Hiroshima and Nagasaki (DS02), an intercomparison study between (152)Eu and (36)Cl measurements was proposed, to reconcile the discrepancy previously observed in the Hiroshima data between measurements and calculations of thermal neutron activation products. Nine granite samples, exposed to the atomic-bomb radiation in Hiroshima within 1,200 m of the hypocenter, as well as mixed standard solutions containing known amounts of europium and chlorine that were neutron-activated by a (252)Cf source, were used for the intercomparison. Gamma-ray spectrometry for (152)Eu was carried out with ultra low-background Ge detectors at the Ogoya Underground Laboratory, Kanazawa University, while three laboratories participated in the (36)Cl measurement using accelerator mass spectrometry (AMS): The Technical University of Munich, Germany, the Lawrence Livermore National Laboratory, USA and the University of Tsukuba, Japan. Measured values for the mixed standard solutions showed good agreement among the participant laboratories. They also agreed well with activation calculations, using the neutron fluences monitored during the (252)Cf irradiation, and the corresponding activation cross-sections taken from the JENDL-3.3 library. The measured-to-calculated ratios obtained were 1.02 for (152)Eu and 0.91-1.02 for (36)Cl, respectively. Similarly, the results of the granite intercomparison indicated good agreement with the DS02 calculation for these samples. An average measured-to-calculated ratio of 0.98 was obtained for all granite intercomparison measurements. The so-called neutron discrepancy that was previously observed and that which included increasing measured-to-calculated ratios for thermal neutron activation products for increasing distances beyond 1,000 m from the hypocenter was not seen in the results of the intercomparison study. The previously claimed discrepancy could be explained by

  2. 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.

  3. Recent advances in AMS of 36Cl with a 3-MV-tandem

    NASA Astrophysics Data System (ADS)

    Martschini, Martin; Forstner, Oliver; Golser, Robin; Kutschera, Walter; Pavetich, Stefan; Priller, Alfred; Steier, Peter; Suter, Martin; Wallner, Anton

    2011-12-01

    Accelerator mass spectrometry (AMS) of 36Cl ( t1/2 = 0.30 Ma) at natural isotopic concentrations requires high particle energies for the separation from the stable isobar 36S and was so far the exclusive domain of tandem accelerators with at least 5 MV terminal voltage. Using terminal foil stripping and a detection setup consisting of a split-anode ionization chamber and an additional energy signal from a silicon strip detector, a 36S suppression of >10 4 at 3 MV terminal voltage was achieved. To further increase the 36S suppression energy loss straggling in various counter gases (C 4H 10, Ar-CH 4 and C 4H 10-Ar) and the effect of "energy focusing" below the maximum of the Bragg curve was investigated. The comparison of experimental data with simulations and published data yielded interesting insights into the physics underlying the detectors. Energy loss, energy straggling and angular scattering determine the 36S suppression. In addition, we improved ion source conditions, target backing materials and the cathode design with respect to sulfur output and cross contamination. These changes allow higher currents during measurement ( 35Cl - current ≈ 5 μA) and also increased the reproducibility. An injector to detector efficiency for 36Cl ions of 8% (16% stripping yield for the 7+ charge state in the accelerator, 50% 36Cl detection efficiency) was achieved, which can favorably be compared to other facilities. The memory effect in our ion source was also thoroughly investigated. Currently our measured blank value is 36Cl/Cl ≈ 3 × 10 -15 when samples with a ratio of 10 -11 are used in the same sample wheel and 36Cl/Cl ≈ 5 × 10 -16 if measured together with samples with a ratio of 10 -12 or below. This is in good agreement with the lowest so far published isotope ratios around 5 × 10 -16 and demonstrates that 3 MV tandems can achieve the same sensitivity for 36Cl as larger machines.

  4. 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.

  5. 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.

  6. 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.

  7. AMS of 36Cl with the VERA 3 MV tandem accelerator

    NASA Astrophysics Data System (ADS)

    Martschini, Martin; Andersson, Pontus; Forstner, Oliver; Golser, Robin; Hanstorp, Dag; Lindahl, Anton O.; Kutschera, Walter; Pavetich, Stefan; Priller, Alfred; Rohlén, Johan; Steier, Peter; Suter, Martin; Wallner, Anton

    2013-01-01

    Recent progress with compact ionization chambers has opened new possibilities for isobar suppression in accelerator mass spectrometry (AMS). Separation of 36Cl (t1/2 = 0.30 Ma) at natural isotopic levels from its stable isobar 36S became feasible at particle energies of 24 MeV, which are also accessible for medium-sized tandem accelerators with 3 MV terminal voltage like VERA (Vienna Environmental Research Accelerator). Investigations with an ionization chamber revealed how physics favors isobar separation even at energies below the maximum of the Bragg curve. The strong energy focusing effect at high energy losses reduces energy straggling significantly and isobar separation steadily increases up to almost full energy loss. With an optimized detection setup, sulfur suppression factors of 2 × 104 have been achieved. Refraining from the additional use of degrader foils has the benefit of high transmission to the detector (∼16%), but requires a low sulfur output from the ion source. Therefore several backing materials have been screened for sulfur content. The dependence of the sulfur output on the AgCl sample size has been investigated as well. Precision and accuracy have been thoroughly assessed over the last two years. Since drifts in the spectra are efficiently corrected by monitoring the position of the 36S peak, the reproducibility for high ratio samples (36Cl/Cl > 10-12) is better than 2%. Our blank value of 36Cl/Cl ≈ (5 ± 5) × 10-16 is competitive to other labs. 36Cl has become a routine AMS-isotope at VERA. Recently we also explored novel techniques for additional sulfur suppression already in the ion source. While results with a small gas reaction cell in front of the sputter target were discouraging, a decrease in the sulfur/chlorine ratio by one order of magnitude was achieved by directing 300 mW continuous wave laser beam at 445 nm towards the cathode in the ion source.

  8. 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.

  9. Tandem-Accelerator Mass-Spectrometry Measurements of 36Cl, 129I and Osmium Isotopes in Diverse Natural Samples

    NASA Astrophysics Data System (ADS)

    Gove, H. E.

    1987-08-01

    Tandem AMS measurements at Rochester in the past few years have mainly involved the radioisotopes 36Cl and 129I, and some work on 10Be, in a variety of terrestrial and extraterrestrial samples. Some measurements have also been made on certain stable isotopes of osmium in meteorites and geological samples from impact craters. Measurements of 36Cl have been made in groundwater and surface rocks for dating purposes, in ice and soil samples containing nuclear-weapon testing fallout for tracing water movement, and in meteorites and Antarctic ice for terrestrial and extraterrestrial meteoritic age determination. Also, 10Be has been measured in a lake sediment, and 36Cl in Greenland ice, through the period of the Maunder minimum; 129I has been measured in hydrological systems, in petroleum and in hydrothermal convection cells in the oceanic crust. Other applications involving measurements of these two radioisotopes include hydrothermal fluids associated with gold mineralization and the determination of the integrity of possible sites for deep nuclear-waste disposal. Previously, the Rochester tandem was employed to measure 14C and isotopes of platinum and iridium in natural samples.

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

    NASA Astrophysics Data System (ADS)

    Kossert, Karsten; Nähle, Ole J.

    2014-03-01

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

  11. 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.

  12. Activation Measurements for Thermal Neutrons, U.S. Measurements of 36Cl in Mineral Samples from Hiroshima and Nagasaki; and Measurement of 63 Ni in Copper Samples From Hiroshima by Accelerator Mass Spectrometry

    SciTech Connect

    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

    2005-01-14

    The present paper presents the {sup 36}Cl measurement effort in the US. A large number of {sup 36}Cl 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 36}Cl 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 36}Cl by bomb neutrons in mineral samples from Hiroshima and Nagasaki was primarily via the reaction {sup 35}Cl(n,{gamma}){sup 36}Cl. 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 36}Cl, typically produces less than 10% of the {sup 36}Cl 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 36}Cl 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 36}Cl as a thermal neutron detector in Hiroshima was first presented by Haberstock et al. who employed the Munich AMS facility to measure {sup 36}Cl/Cl ratios in a gravestone from near the hypocenter. That work subsequently resulted in an expanded {sup 36}Cl effort in Germany that paralleled the US work. More recently, there have also been {sup 36}Cl measurements made by a Japanese

  13. 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.

  14. Re-measurement of the 33S(α ,p )36Cl cross section for early solar system nuclide enrichment

    NASA Astrophysics Data System (ADS)

    Anderson, Tyler; Skulski, Michael; Clark, Adam; Nelson, Austin; Ostdiek, Karen; Collon, Philippe; Chmiel, Greg; Woodruff, Tom; Caffee, Marc

    2017-07-01

    Short-lived radionuclides (SLRs) with half-lives less than 100 Myr are known to have existed around the time of the formation of the solar system around 4.5 billion years ago. Understanding the production sources for SLRs is important for improving our understanding of processes taking place just after solar system formation as well as their timescales. Early solar system models rely heavily on calculations from nuclear theory due to a lack of experimental data for the nuclear reactions taking place. In 2013, Bowers et al. measured 36Cl production cross sections via the 33S(α ,p ) reaction and reported cross sections that were systematically higher than predicted by Hauser-Feshbach codes. Soon after, a paper by Peter Mohr highlighted the challenges the new data would pose to current nuclear theory if verified. The 33S(α ,p )36Cl reaction was re-measured at five energies between 0.78 MeV/nucleon and 1.52 MeV/nucleon, in the same range as measured by Bowers et al., and found systematically lower cross sections than originally reported, with the new results in good agreement with the Hauser-Feshbach code talys. Loss of Cl carrier in chemical extraction and errors in determination of reaction energy ranges are both possible explanations for artificially inflated cross sections measured in the previous work.

  15. Perchlorate isotope forensics with naturally produced 36Cl

    NASA Astrophysics Data System (ADS)

    Hillegonds, D.; Parker, D.; Singleton, M.; Buchholz, B.; Esser, B.; Moran, J.; Rood, D.; Finkel, R.

    2008-12-01

    The source of perchlorate (ClO4-) in many surface and groundwaters is not known. Recent studies (Parker et al., 2008) suggest that natural production is widespread and common, and may involve atmospheric processes. The isotopic composition of perchlorate chlorine and oxygen has proven useful for identifying anthropogenic/natural perchlorate sources (Bohlke et al, 2005) and for exploring biodegradation in environmental samples (Sturchio et al, 2007). The stable isotope approach, however, requires processing very large volumes of water to obtain milligrams of rigorously separated perchlorate for analysis, limiting its widespread application. Chlorine-36 (36Cl) is a long-lived and rare radionuclide produced cosmogenically in the upper atmosphere. The measurement of 36Cl/Cl by accelerator mass spectrometry (AMS) only requires micrograms of sample chlorine enabling lower volume extractions (less than 1/10th that required for stable isotope techniques), and potentially less rigorous perchlorate chemistry. The primary technical goal of our work is to determine the utility of 36Cl in distinguishing perchlorate source and in constraining mechanisms of natural perchlorate formation. We expect that synthetic perchlorate compounds produced using chloride brines from ancient sources and concentrated modern deposits will have low 36Cl/Cl ratios that will be distinct from natural perchlorate produced in the atmosphere. High levels of 36Cl in groundwater or rainwater perchlorate would then be an unambiguous indication of a natural atmospheric production, and the distribution of 36Cl/Cl in precipitation and groundwater (in conjunction with stable isotope compositions) would constrain the mechanism for natural perchlorate production in the atmosphere. Using accelerator mass spectrometry (AMS), we have measured 36Cl/Cl in a number of synthetic perchlorate salts (including potassium, sodium, magnesium, and ammonium salts). Synthetic salt 36Cl/Cl atom ratios range from 1 to 35 e-15

  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. 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.

  18. 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.

  19. 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

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

    PubMed

    Poghosyan, Armen; Sturchio, Neil C

    2015-06-01

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

  1. 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.

  2. 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.

  3. Carbonate and silicate rock standards for cosmogenic 36Cl

    NASA Astrophysics Data System (ADS)

    Mechernich, Silke; Dunai, Tibor J.; Binnie, Steven A.; Goral, Tomasz; Heinze, Stefan; Dewald, Alfred; Benedetti, Lucilla; Schimmelpfennig, Irene; Phillips, Fred; Marrero, Shasta; Akif Sarıkaya, Mehmet; Gregory, Laura C.; Phillips, Richard J.; Wilcken, Klaus; Simon, Krista; Fink, David

    2017-04-01

    The number of studies using cosmogenic nuclides has increased multi-fold during the last two decades and several new dedicated target preparation laboratories and Accelerator Mass Spectrometry (AMS) facilities have been established. Each facility uses sample preparation and AMS measurement techniques particular to their needs. It is thus desirable to have community-accepted and well characterized rock standards available for routine processing using identical target preparation procedures and AMS measurement methods as carried out for samples of unknown cosmogenic nuclide concentrations. The usefulness of such natural standards is that they allow more rigorous quality control, for example, the long-term reproducibility of results and hence measurement precision, or the testing of new target preparation techniques or newly established laboratories. This is particularly pertinent for in-situ 36Cl studies due to the multiplicity of 36Cl production pathways that requires a variety of elemental and isotopic determinations in addition to AMS 36Cl assay. We have prepared two natural rock samples (denoted CoCal-N and CoFsp-N) to serve as standard material for in situ-produced cosmogenic 36Cl analysis. The sample CoCal-N is a pure limestone prepared from pebbles in a Namibian lag deposit, while the alkali-feldspar CoFsp-N is derived from a single crystal in a Namibian pegmatite. The sample preparation took place at the University of Cologne, where first any impurities were removed manually from both standards. CoCal-N was leached in 10 % HNO3 to remove the outer rim, and afterwards crushed and sieved to 250-500 μm size fractions. CoFsp-N was crushed, sieved to 250-500 μm size fractions and then leached in 1% HNO3 / 1% HF until 20% of the sample were removed. Both standards were thoroughly mixed using a rotating sample splitter before being distributed to other laboratories. To date, a total of 28 CoCal-N aliquots (between 2 and 16 aliquots per facility) and 31 Co

  4. Recent results of measurements of the {sup 14}N(n,p){sup 14}C, {sup 35}Cl(n,p){sup 35}S, {sup 36}Cl(n,p){sup 36}S, and {sup 36}Cl(n,{alpha}){sup 33}P reaction cross sections

    SciTech Connect

    Gledenov, Y.M.; Salatski, V.I.; Sedyshev, P.V.; Sedysheva, M.V.; Koehler, P.E.; Vesna, V.A.; Okunev, I.S.

    1995-02-05

    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 36}Cl(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 36}Cl(n,p){sup 36}S and {sup 36}Cl(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 36}Cl(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}.

  5. 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.

  6. 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.

  7. {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.

  8. 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.

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

    PubMed

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

    2007-04-15

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

  10. 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.

  11. 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.

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

    NASA Astrophysics Data System (ADS)

    Mai, K.

    2009-09-01

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

  13. 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

    greater than values for sodalite in some CAIs and chondrules. We report here new {sup 36}Cl-{sup 36}S isotope measurements of wadalite in two Type B CAIs (TS34 and Egg-6) and sodalite in a fine-grained CAI (Pink Angel) from Allende.

  14. 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.

  15. Progress in AMS measurements at the LLNL spectrometer. [Accelerator Mass Spectroscopy (AMS)

    SciTech Connect

    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.

    1991-06-01

    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 36}Cl, are presently testing the spectrometer performance for {sup 26}Al and {sup 3}H, and will begin tests on {sup 7}Be, {sup 41}Ca 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.

  16. 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

  17. 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.

  18. 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.

  19. Determination of Cl impurities and {sup 36}Cl instant release from used CANDU fuels

    SciTech Connect

    Tait, J.C.; McConnell, J.; Wilkin, D.L.; Cornett, R.J.J.; Chant, L.A.; Jirovec, J.

    1997-12-31

    Chlorine-36 has been identified as a potential source of radiological risk in the disposal of nuclear fuel waste. The radioisotope {sup 36}Cl (t{sub 1/2} = 3 {times} 10{sup 5} a) is produced by neutron activation of Cl impurities in UO{sub 2} fuel. The total average Cl impurity level in four unirradiated CANDU UO{sub 2} fuel samples was 2.3 {+-} 1.1 ppm. ORIGEN-S calculations using a 5 ppm Cl impurity in a CANDU fuel resulted in a {sup 36}Cl activity comparable to the activity of {sup 129}I and {sup 14}C produced in the fuel thus requiring {sup 36}Cl to be considered in disposal risk assessments. The instant release of {sup 365}Cl from the gap and grain boundary regions of the fuel to solution was measured by leaching both clad fuel and fuel samples crushed to grain-sized particles. The {sup 36}Cl releases from fuel samples taken from 8 different fuel bundles ranged from 0.5% to 20.4% of the total {sup 36}Cl inventory over a leaching period of 32 days. The {sup 36}Cl released was found to correlate with the stable Xe gas release, the fuel burnup and the linear power rating (LPR). For a typical CANDU fuel with an LPR of {approximately}42 kW/m, the instant release of {sup 36}Cl would be about 5% of the total inventory.

  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. 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. "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

  3. Actinide measurements by AMS using fluoride matrices

    NASA Astrophysics Data System (ADS)

    Cornett, R. J.; Kazi, Z. H.; Zhao, X.-L.; Chartrand, M. G.; Charles, R. J.; Kieser, W. E.

    2015-10-01

    Actinides can be measured by alpha spectroscopy (AS), mass spectroscopy or accelerator mass spectrometry (AMS). We tested a simple method to separate Pu and Am isotopes from the sample matrix using a single extraction chromatography column. The actinides in the column eluent were then measured by AS or AMS using a fluoride target matrix. Pu and Am were coprecipitated with NdF3. The strongest AMS beams of Pu and Am were produced when there was a large excess of fluoride donor atoms in the target and the NdF3 precipitates were diluted about 6-8 fold with PbF2. The measured concentrations of 239,240Pu and 241Am agreed with the concentrations in standards of known activity and with two IAEA certified reference materials. Measurements of 239,240Pu and 241Am made at A.E. Lalonde AMS Laboratory agree, within their statistical uncertainty, with independent measurements made using the IsoTrace AMS system. This work demonstrated that fluoride targets can produce reliable beams of actinide anions and that the measurement of actinides using fluorides agree with published values in certified reference materials.

  4. Holocene Time-slip history of normal fault scarps in western Turkey: 36Cl surface exposure dating

    NASA Astrophysics Data System (ADS)

    Mozafari Amiri, N.; Sümer, Ö.; Tikhomirov, D.; Özkaymak, Ç.; Uzel, B.; Ivy-Ochs, S.; Vockenhuber, C.; Sözbilir, H.; Akçar, N.

    2016-12-01

    Bedrock fault scarps built in carbonates are the most direct evidence of past earthquakes to reconstruct long-term seismic outline using 36Cl cosmogenic nuclides. The western Anatolia is an active seismic region, in which several major graben systems are formed mainly in carbonates commenced by roughly N-S extensional regime since the early Miocene. The oldest known earthquake in the Eastern Mediterranean and Middle East dates back to 464 B.C. However, to evaluate the earthquake pattern, a complete seismic data over a large time-scale is required. For modelling of seismic periods, a Matlab® code is used based on acceleration of production rate of 36Cl following exposure of fresh material to cosmic rays. By measuring the amount of cosmogenic 36Cl versus height on the fault surface, the timing of significant ruptures and vertical displacements are explored. The best scenario is obtained with the minimum difference between the modelled and measured 36Cl. An ideal target spot is a minimum-eroded surface with length of at least two meters from the intersection of the fault with colluvium. After continuous marking of 10 cm height and 15 cm width on the fault, the samples of 3 cm thick are collected. The geometrical factors of scarp dip, scarp height, top surface dip and colluvium dip are measured. Topographic shielding, density of the fault scarp and colluvium are also estimated. Afterwards, the samples are physically and chemically prepared in laboratory for elemental analysis and AMS measurements. In this study, we collected 584 samples from seven major faults in western Anatolia. Our first results indicate five earthquake sequences in the Priene-Sazlı fault since early Holocene with a recurrence interval of approximately 2000 years and slip of 1.3 to 2.9 meters. The two most recent ruptures are correlated with 1955 and 68 AD earthquakes. A slip rate of roughly 1 mm/yr throughout the activity periods is estimated. Regarding the rupture length, the fault has potential

  5. 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

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

    SciTech Connect

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

    1990-10-01

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

  7. 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

  8. Radiocarbon measurements at the CSIRO AMS facility

    NASA Astrophysics Data System (ADS)

    Sie, S. H.; Leaney, F.; Gillespie, R.; Suter, G. F.; Ryan, C. G.

    1994-06-01

    The CSIRO AMS facility based on a 3 MV Tandetron at the HIAF (Heavy Ion Analytical Facility) laboratory became operational in 1990 for 14C measurements, achieving 2-4% precision. The main drive behind the AMS development is its potential use in exploration, and although the cosmogenic isotopes are potentially useful in regolith studies, the emphasis is shifting towards the development of the capability of in-situ detection of ultra traces of heavy stable isotopes and geochronology. The 14C capability, and other cosmogenic isotopes, will continue to be developed, to meet other CSIRO interests, e.g. in environmental problems.

  9. 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.

  10. AMS at ANTARES - The first 10 years

    NASA Astrophysics Data System (ADS)

    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.

    2000-10-01

    The status and capabilities of the ANTARES AMS facility after 10 years are reviewed. The common AMS radioisotopes, 10Be, 14C, 26Al, 36Cl 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.

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

    SciTech Connect

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

    1994-11-01

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

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. Estimating the AmLi Neutron Spectrum from Measured Ring Ratios

    SciTech Connect

    Weinmann-Smith, Robert; Beddingfield, David H.; Enqvist, Andreas; Swinhoe, Martyn Thomas

    2016-11-10

    These are a set of slides on estimating the AmLi neutron spectrum from measured ring ratios. The IAEA uses an AmLi source in the Uranium Neutron Coincidence Collar (UNCL) to verify compliance with nonproliferation treaties. The UNCL requires calibration with known uranium samples. The AmLi spectrum isn’t known well enough to allow simulated calibrations. Alphas lose energy traveling through AmO2 particle of unknown size. Energy reduction below Li threshold enhances O contribution. Unknown Li matrix material affects neutron production and thermalization. There is large variation in spectra from each element. Other topics covered include: applications, physics considerations, current spectra, measurement overview, measurement results - variation between sources, simulations, spectra fitting, other simulations, and conclusions.

  1. 50 CFR 648.163 - Bluefish Accountability Measures (AMs).

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 50 Wildlife and Fisheries 12 2012-10-01 2012-10-01 false Bluefish Accountability Measures (AMs... Management Measures for the Atlantic Bluefish Fishery § 648.163 Bluefish Accountability Measures (AMs). (a... the transfer process described in § 648.162, then any overage will be measured against that state's...

  2. 50 CFR 648.163 - Bluefish Accountability Measures (AMs).

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 50 Wildlife and Fisheries 12 2013-10-01 2013-10-01 false Bluefish Accountability Measures (AMs... Management Measures for the Atlantic Bluefish Fishery § 648.163 Bluefish Accountability Measures (AMs). (a... the transfer process described in § 648.162, then any overage will be measured against that state's...

  3. Groundwater tracing with nucleogenic 36Cl in West Canning Basin, Western Australia

    NASA Astrophysics Data System (ADS)

    Wilcken, Klaus; Cendón, Dioni I.; Meredith, Karina; Simon, Krista; Stopic, Attila; Peterson, Mark; Hankin, Stuart

    2017-04-01

    Chlorine-36 has been used over the past 20-30 years as a groundwater tracer in many hydrological studies and is a well-established dating technique. Given the half-life of 301 kyr it is well suited for dating of 'old' groundwater between 50 kyr - 1 Myr. A challenge associated with utilising 36Cl as a tracer is that it can be produced via three different pathways that will influence the result based on the unique hydrogeological setting of a study area. Typically the dominant source of 36Cl in groundwater is atmospheric 36Cl that is produced at troposphere and stratosphere via interaction of cosmic-ray protons and secondary neutrons with Ar. However, the secondary cosmic-ray neutrons can similarly produce 36Cl in surface rocks particularly at high elevations. Also nucleogenic production of 36Cl at subsurface environments can become significant, especially if U and/or Th concentrations are high. Delineating and quantifying these processes is essential when using 36Cl as a groundwater dating tool. In contrast to a conservative situation where atmospheric 36Cl dominates, we present a study in the West Canning Basin located in the Pilbara region of Western Australia, where the 36Cl/Cl ratio increases from ˜30×10-15 near the recharge zone to 100×10-15 over a 60 km of flow path within a confined aquifer. Additional isotopic evidence (14C and 87Sr/86Sr) in groundwater, mineralogy (X-Ray diffraction) and elemental analysis (Neutron Activation) of whole-rock powder samples from the aquifer and overlying geological units, is used to establish an interpretation that nucleogenic 36Cl production is effectively the only potential process to explain the data. Nucleogenic production can influence the groundwater 36Cl content in two different ways: (1) as an additional input of Cl with a 36Cl/Cl ratio that reflects the neutron flux within the particular mineralogy; or (2) via "in-situ" production of 36Cl directly in the groundwater from the dissolved 35Cl where the rate is

  4. 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

  5. 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

  6. 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

  7. 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

  8. 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.

  9. AMS applied to Hiroshima and Chernobyl dosimetry

    SciTech Connect

    Straume, T.; Marchetti, A.A.; Anspaugh, L.R.

    1995-12-01

    Two projects employing AMS are summarized and updated. One project employs AMS to measure {sup 36}Cl in concrete and other mineral samples from Hiroshima and Nagasaki to help reconstruct neutron fluences received by the atom-bomb survivors. In this project, we have demonstrated a large discrepancy between the neutron activation measured in Hiroshima and predictions based on the current dosimetry system. This discrepancy has practical implications for radiation risk assessment and radiation protection standards. The other project employs AMS to measure {sup 129}I in soil and other environmental samples from Belarus, Ukraine, and Russia. This is a proof-of-principle study to determine if the long lived {sup 129}I isotope (half life, 16 x 10{sup 6} y) measured by AMS can be used to reconstruct deposition of the short lived {sup 131}I isotope from the 1986 Chernobyl reactor accident. This is required because {sup 131}I disappeared before adequate measurements could be made.

  10. 241Am (n,gamma) isomer ratio measurement

    SciTech Connect

    Bond, Evelyn M; Vieira, David J; Moody, Walter A; Slemmons, Alice K

    2011-01-05

    The objective of this project is to improve the accuracy of the {sup 242}Cm/{sup 241}Am radiochemistry ratio. We have performed an activation experiment to measure the {sup 241}Am(n,{gamma}) cross section leading to either the ground state of {sup 242g}Am (t{sub 1/2} = 16 hr) which decays to {sup 242}Cm (t{sub 1/2} = 163 d) or the long-lived isomer {sup 242m}Am (t{sub 1/2} = 141 yr). This experiment will develop a new set of americium cross section evaluations that can be used with a measured {sup 242}Cm/{sup 241}Am radiochemical measurement for nuclear forensic purposes. This measurement is necessary to interpret the {sup 242}Cm/{sup 241}Am ratio because a good measurement of this neutron capture isomer ratio for {sup 241}Am does not exist. The targets were prepared in 2007 from {sup 241}Am purified from LANL stocks. Gold was added to the purified {sup 241}Am as an internal neutron fluence monitor. These targets were placed into a holder, packaged, and shipped to Forschungszentrum Karlsruhe, where they were irradiated at their Van de Graff facility in February 2008. One target was irradiated with {approx}25 keV quasimonoenergetic neutrons produced by the {sup 7}Li(p,n) reaction for 3 days and a second target was also irradiated for 3 days with {approx}500 keV neutrons. Because it will be necessary to separate the {sup 242}Cm from the {sup 241}Am in order to measure the amount of {sup 242}Cm by alpha spectrometry, research into methods for americium/curium separations were conducted concurrently. We found that anion exchange chromatography in methanol/nitric acid solutions produced good separations that could be completed in one day resulting in a sample with no residue. The samples were returned from Germany in July 2009 and were counted by gamma spectrometry. Chemical separations have commenced on the blank sample. Each sample will be spiked with {sup 244}Cm, dissolved and digested in nitric acid solutions. One third of each sample will be processed at a time

  11. Aerial Measuring System (AMS) Baseline Surveys for Emergency Planning

    SciTech Connect

    Lyons, C

    2012-06-04

    Originally established in the 1960s to support the Nuclear Test Program, the AMS mission is to provide a rapid and comprehensive worldwide aerial measurement, analysis, and interpretation capability in response to a nuclear/radiological emergency. AMS provides a responsive team of individuals whose processes allow for a mission to be conducted and completed with results available within hours. This presentation slide-show reviews some of the history of the AMS, summarizes present capabilities and methods, and addresses the value of the surveys.

  12. 50 CFR 648.233 - Spiny dogfish Accountability Measures (AMs).

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 50 Wildlife and Fisheries 10 2011-10-01 2011-10-01 false Spiny dogfish Accountability Measures... Management Measures for the Spiny Dogfish Fishery § 648.233 Spiny dogfish Accountability Measures (AMs). (a... dogfish on that date for the remainder of that semi-annual period by publishing notification in the...

  13. 50 CFR 648.233 - Spiny dogfish Accountability Measures (AMs).

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 50 Wildlife and Fisheries 12 2013-10-01 2013-10-01 false Spiny dogfish Accountability Measures... Management Measures for the Spiny Dogfish Fishery § 648.233 Spiny dogfish Accountability Measures (AMs). (a... dogfish on that date for the remainder of that semi-annual period by publishing notification in the...

  14. 50 CFR 648.233 - Spiny dogfish Accountability Measures (AMs).

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 50 Wildlife and Fisheries 12 2014-10-01 2014-10-01 false Spiny dogfish Accountability Measures... Management Measures for the Spiny Dogfish Fishery § 648.233 Spiny dogfish Accountability Measures (AMs). (a... quota described in § 648.232 will be harvested and shall close the EEZ to fishing for spiny dogfish on...

  15. 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.

  16. Tissue distribution, elimination, and metabolism of sodium [36Cl]perchlorate in lactating goats.

    PubMed

    Smith, David J; Hakk, Heldur; Larsen, Gerald L

    2006-11-15

    Perchlorate has contaminated water sources throughout the United States but particularly in the arid Southwest, an area containing large numbers of people and few water sources. Recent studies have demonstrated that perchlorate is present in alfalfa and that perchlorate is secreted into the milk of cows. Studies in lactating cows have indicated that only a small portion of a perchlorate dose could be accounted for by elimination in milk, feces, or urine. It was hypothesized that the remainder of the perchlorate dose was excreted as chloride ion. The purpose of this study was to determine the fate and disposition of (36)Cl-perchlorate in lactating dairy goats. Two goats (60 kg) were each orally administered 3.5 mg (16.5 muCi) of (36)Cl-perchlorate, a dose selected to approximate environmental perchlorate exposure but that would allow for adequate detection of radioactive residues after a 72 h withdrawal period. Blood, milk, urine, and feces were collected incrementally until slaughter at 72 h. Total radioactive residue (TRR) and perchlorate concentrations were measured using radiochemical techniques and liquid chromatography mass spectrometry (LC-MS-MS). Peak blood levels of TRR occurred at 12 h ( approximately 195 ppb) postdose; peak levels of parent perchlorate, however, occurred after only 2 h, suggesting that perchlorate metabolism occurred rapidly in the rumen. The serum half-life of perchlorate was estimated to be 2.3 h. After 24 h, perchlorate was not detectable in blood serum but TRR remained elevated (160 ppb) through 72 h. Milk perchlorate levels peaked at 12 h (155 ppb) and were no longer detectable by 36 h, even though TRRs were readily detected through 72 h. Perchlorate was not detectable in skeletal muscle or liver at slaughter (72 h). Chlorite and chlorate were not detected in any matrix. The only radioactive residues observed were perchlorate and chloride ion. Bioavailability of perchlorate was poor in lactating goats, but the perchlorate that was

  17. Further study on highly sensitive AMS measurement of 53Mn

    NASA Astrophysics Data System (ADS)

    Kejun, Dong; Hao, Hu; Xianggao, Wang; Chaoli, Li; Ming, He; Zhenyu, Li; Shaoyong, Wu; Jiancheng, Liu; Guowen, Zheng; Heng, Li; Zhigang, Chen; Guangshan, Liu; Jian, Yuan; Shan, Jiang

    2012-08-01

    The AMS facility at China Institute of Atomic Energy has been equipped with a ΔE-Q3D detection system for the measurements of 53Mn. While the sample material of MnO2 and the extraction ions of MnO- were used previously in AMS measurement of 53Mn with fairly good results, a method has recently been developed with the extraction of MnF- from ion source using MnF2 and MnO2 + PbF2 as sample materials. As a result, a sensitivity of 10-14 (53Mn/Mn) has been achieved. Compared with the original MnO-/MnO2 approach, the method of MnF- extraction, combined with ΔE-Q3D detection technique, demonstrated an improved sensitivity for AMS measurement of 53Mn.

  18. PRIME lab AMS performance, upgrades and research applications

    NASA Astrophysics Data System (ADS)

    Sharma, P.; Bourgeois, M.; Elmore, D.; Granger, D.; Lipschutz, M. E.; Ma, X.; Miller, T.; Mueller, K.; Rickey, F.; Simms, P.; Vogt, S.

    2000-10-01

    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, 26Al, 36Cl, 41Ca 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, 26Al, 36Cl and 41Ca 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 36Cl mapping. Radionuclide concentrations are also determined in meteorites and tektites for deciphering space and terrestrial exposure histories.

  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. 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

  1. 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

  2. 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

  3. Validation of an ambient measurement system (AMS) for walking speed.

    PubMed

    Varsanik, Jonathan S; Kimmel, Zebadiah M; de Moor, Carl; Gabel, Wendy; Phillips, Glenn A

    2017-07-01

    Walking speed is an important indicator of worsening in a variety of neurological and neuromuscular diseases, yet typically is measured only infrequently and in a clinical setting. Passive measurement of walking speed at home could provide valuable information to track the progression of many neuromuscular conditions. The purpose of this study was to validate the measurement of walking speed by a shelf-top ambient measurement system (AMS) that can be placed in a patient's home. Twenty-eight healthy adults (16 male, 12 female) were asked to walk three pre-defined routes two times each (total of 168 traversals). For each traversal, walking speed was measured simultaneously by five sources: two independent AMSs and three human timers with stopwatches. Measurements across the five sources were compared by generalised estimating equations (GEE). Correlation coefficients compared pairwise for walking speeds across the two AMSs, three human timers, and three routes all exceeded 0.86 (p < .0001), and for AMS-to-AMS exceeded 0.92 (p < .0001). Aggregated across all routes, there was no significant difference in measured walking speeds between the two AMSs (p = .596). There was a statistically significant difference between the AMSs and human timers of 8.5 cm/s (p < .0001), which is comparable to differences reported for other non-worn sensors. The tested AMS demonstrated the ability to automatically measure walking speeds comparable to manual observation and recording, which is the current standard for assessing walking speed in a clinical setting. The AMS may be used to detect changes in walking speed in community settings.

  4. 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

  5. Evaluation of Am-Li neutron spectra data for active well type neutron multiplicity measurements of uranium

    NASA Astrophysics Data System (ADS)

    Goddard, Braden; Croft, Stephen; Lousteau, Angela; Peerani, Paolo

    2016-09-01

    Safeguarding nuclear material is an important and challenging task for the international community. One particular safeguards technique commonly used for uranium assay is active neutron correlation counting. This technique involves irradiating unused uranium with (α, n) neutrons from an Am-Li source and recording the resultant neutron pulse signal which includes induced fission neutrons. Although this non-destructive technique is widely employed in safeguards applications, the neutron energy spectra from an Am-Li sources is not well known. Several measurements over the past few decades have been made to characterize this spectrum; however, little work has been done comparing the measured and theoretical spectra of various Am-Li sources to each other. This paper examines fourteen different Am-Li spectra, focusing on how these spectra affect simulated neutron multiplicity results using the code Monte Carlo N-Particle eXtended (MCNPX). Two measurement and simulation campaigns were completed using Active Well Coincidence Counter (AWCC) detectors and uranium standards of varying enrichment. The results of this work indicate that for standard AWCC measurements, the fourteen Am-Li spectra produce similar doubles and triples count rates. The singles count rates varied by as much as 20% between the different spectra, although they are usually not used in quantitative analysis, being dominated by scattering which is highly dependent on item placement.

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

    PubMed

    Guerin, M

    2001-10-01

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

  7. 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.

  8. Cosmogenic 36Cl glacial chronologies of the Mount Geyikdaǧ (Southern Turkey)

    NASA Astrophysics Data System (ADS)

    Ciner, Attila; Akif Sarıkaya, Mehmet; Yıldırım, Cengiz

    2017-04-01

    We report the timing of advances of glaciers during the Late Pleistocene in the Mount Geyikdaǧ (36.53oN, 32.10oE, 2877 m), situated in the central Taurus Mountains of Turkey. Several piedmont glaciers originated from the Geyikdaǧ ice cap (˜40 km2), situated between 2350-2650 m above sea level (a.s.l.) and deeply carved the north-facing hill slopes before reaching the Namaras Valley (2000-2050 m a.s.l). The hummocky moraines resulted from in-situ deposition of stagnant glacier ice where debris cover was heterogeneously distributed on the glacier surface. Boulders from hummocky, disintegration, lateral and terminal moraines from the Namaras, Susam, Çimi and Güneycik valleys (1750-2200 m a.s.l.) were dated by terrestrial cosmogenic nuclide (TCN) 36Cl surface exposure dating. A total of seventy-four boulder ages indicate at least four phases of deglaciation during the Late Pleistocene. Our results indicate that during the Last Glacial Maximum (LGM), glaciers reached their maximum positions at 20.4±4.4 ka and 19.5±2.5 ka ago (1σ; ka = 1000 calendar years). This date is in accordance with the local glacial maximum, represented by piedmont glaciers (18.0±1.1 ka) in the northern side of the mountain. Glaciers started to retreat after the LGM and shortly stabilized or re-advanced three times before they completely vanished out. The first stage ended between 17.1±3.8 ka and 14.2±1.5 ka ago during the Late-glacial. Later, glaciers re-advanced during the Younger Dryas stadial (between 12.7±2.1 ka and 11.6±1.3 ka ago). The last glaciation occurred during the Holocene 8.9±1.2 ka and 5.2±1.0 ka ago. Later, glaciers mostly vanished from the study area, but a few rock glaciers developed during the Late Holocene. Additionally, from a well-preserved moraine loop and a rock glacier inside that loop, we also obtained contrasting TCN 36Cl inventories. We measured 4 samples from each landform and obtained the weighted average ages of 5.3±1.2 ka and 11.8±1.5 ka for the

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

    USDA-ARS?s Scientific Manuscript database

    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...

  10. 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.

  11. Millennial strain partitioning revealed by 36Cl cosmogenic data on active bedrock fault scarps from Abruzzo, Italy

    NASA Astrophysics Data System (ADS)

    Gregory, Laura; Roberts, Gerald; Cowie, Patience; Wedmore, Luke; McCaffrey, Ken; Shanks, Richard; Zijerveld, Leo; Phillips, Richard

    2017-04-01

    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. Measuring earthquake slip histories 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 millennial resolution. In this presentation, we present new 36Cl data combined with historical earthquake records to document orogen-wide changes in the distribution of seismicity on millennial timescales in Abruzzo, central Italy. Seismic activity due to extensional faulting was concentrated on the northwest side of the mountain range during the historical period, or since approximately the 14th century. Seismicity is more limited on the southwest side of Abruzzo during historical times. This pattern has led some to suggest that faults on the southwest side of Abruzzo are not active, however clear fault scarps cutting Holocene-aged slopes are well preserved across the whole of the orogen. These scarps preserve an excellent record of Late Pleistocene to Holocene earthquake activity, which can be quantified using cosmogenic isotopes that track the exposure of the bedrock fault scarps. 36Cl accumulates in the fault scarps as the plane is progressively exhumed by earthquakes and the concentration of 36Cl measured up the fault plane reflects the rate and patterns of slip. We utilise Bayesian modelling techniques to estimate slip histories based on the cosmogenic data. Each sampling site is carefully characterised using LiDAR and GPR to ensure that fault plane exposure is due to slip during earthquakes and not sediment transport processes. In

  12. Impact of AMS-02 Measurements on Reducing GCR Model Uncertainties

    NASA Technical Reports Server (NTRS)

    Slaba, T. C.; O'Neill, P. M.; Golge, S.; Norbury, J. W.

    2015-01-01

    For vehicle design, shield optimization, mission planning, and astronaut risk assessment, the exposure from galactic cosmic rays (GCR) poses a significant and complex problem both in low Earth orbit and in deep space. To address this problem, various computational tools have been developed to quantify the exposure and risk in a wide range of scenarios. Generally, the tool used to describe the ambient GCR environment provides the input into subsequent computational tools and is therefore a critical component of end-to-end procedures. Over the past few years, several researchers have independently and very carefully compared some of the widely used GCR models to more rigorously characterize model differences and quantify uncertainties. All of the GCR models studied rely heavily on calibrating to available near-Earth measurements of GCR particle energy spectra, typically over restricted energy regions and short time periods. In this work, we first review recent sensitivity studies quantifying the ions and energies in the ambient GCR environment of greatest importance to exposure quantities behind shielding. Currently available measurements used to calibrate and validate GCR models are also summarized within this context. It is shown that the AMS-II measurements will fill a critically important gap in the measurement database. The emergence of AMS-II measurements also provides a unique opportunity to validate existing models against measurements that were not used to calibrate free parameters in the empirical descriptions. Discussion is given regarding rigorous approaches to implement the independent validation efforts, followed by recalibration of empirical parameters.

  13. 47 CFR 73.61 - AM directional antenna field strength measurements.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 4 2013-10-01 2013-10-01 false AM directional antenna field strength... RADIO SERVICES RADIO BROADCAST SERVICES AM Broadcast Stations § 73.61 AM directional antenna field strength measurements. (a) Each AM station using a directional antenna with monitoring point...

  14. 47 CFR 73.61 - AM directional antenna field strength measurements.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 4 2011-10-01 2011-10-01 false AM directional antenna field strength... RADIO SERVICES RADIO BROADCAST SERVICES AM Broadcast Stations § 73.61 AM directional antenna field strength measurements. (a) Each AM station using a directional antenna with monitoring point...

  15. 47 CFR 73.61 - AM directional antenna field strength measurements.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false AM directional antenna field strength... RADIO SERVICES RADIO BROADCAST SERVICES AM Broadcast Stations § 73.61 AM directional antenna field strength measurements. (a) Each AM station using a directional antenna with monitoring point...

  16. 47 CFR 73.61 - AM directional antenna field strength measurements.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 4 2014-10-01 2014-10-01 false AM directional antenna field strength... RADIO SERVICES RADIO BROADCAST SERVICES AM Broadcast Stations § 73.61 AM directional antenna field strength measurements. (a) Each AM station using a directional antenna with monitoring point...

  17. 47 CFR 73.61 - AM directional antenna field strength measurements.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 4 2012-10-01 2012-10-01 false AM directional antenna field strength... RADIO SERVICES RADIO BROADCAST SERVICES AM Broadcast Stations § 73.61 AM directional antenna field strength measurements. (a) Each AM station using a directional antenna with monitoring point...

  18. Neutron capture and (n,2n) measurements on 241Am

    SciTech Connect

    Vieira, D; Jandel, M; Bredeweg, T; Bond, E; Clement, R; Couture, A; Haight, R; O'Donnell, J; Reifarth, R; Ullmann, J; Wilhelmy, J; Wouters, J; Tonchev, A; Hutcheson, A; Angell, C; Crowell, A; Fallin, B; Hammond, S; Howell, C; Karowowski, H; Kelley, J; Pedroni, R; Tornow, W; Macri, R; Agvaanluvsan, U; Becker, J; Dashdorj, D; Stoyer, M; Wu, C

    2007-07-18

    We report on a set of neutron-induced reaction measurements on {sup 241}Am which are important for nuclear forensics and advanced nuclear reactor design. Neutron capture measurements have been performed on the DANCE detector array at the Los Alamos Neutron Scattering CEnter (LANSCE). In general, good agreement is found with the most recent data evaluations up to an incident neutron energy of {approx} 300 keV where background limits the measurement. Using mono-energetic neutrons produced in the {sup 2}H(d,n){sup 3}He reaction at Triangle University Nuclear Laboratory (TUNL), we have measured the {sup 241}Am(n,2n) excitation function from threshold (6.7 MeV) to 14.5 MeV using the activation method. Good agreement is found with previous measurements, with the exception of the three data points reported by Perdikakis et al. around 11 MeV, where we obtain a much lower cross section that is more consistent with theoretical estimates.

  19. Radiocarbon measurement with 1 MV AMS at charge state 1+

    NASA Astrophysics Data System (ADS)

    Sung, K. H.; Hong, W.; Park, G.; Lee, J. G.

    2015-10-01

    A 1 MV AMS was installed at KIGAM (Korea Institute of Geoscience and Mineral Resources) in 2007. We usually measure 14C at charge state 2+ because beam transmission yield reaches maximum value at a terminal voltage of 950 kV. However, this condition always has the possibility of interference by Li22+ molecules. To avoid the interference, samples with high Li contents need to be measured with charge states 1+ or 3+ because lithium ions only form the even charge states. Therefore, it was necessary to investigate the operating conditions of our AMS machine with charge state 1+ or 3+. The optimized condition for 1+ measurement was found to be 500 kV for terminal voltage and 2.5 × 10-2 mbar for stripper gas pressure. After setting up operating conditions for measurement with C1+, standard (IAEA C1, C7 and C8), blank, unknown wood and charcoal samples were measured and the results were compared with those obtained with a C2+ beam. The background level was determined to be as low as 2-5 × 10-15 for 14C1+.

  20. 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

  1. Radiocarbon measurements of small gaseous samples at CologneAMS

    NASA Astrophysics Data System (ADS)

    Stolz, A.; Dewald, A.; Altenkirch, R.; Herb, S.; Heinze, S.; Schiffer, M.; Feuerstein, C.; Müller-Gatermann, C.; Wotte, A.; Rethemeyer, J.; Dunai, T.

    2017-09-01

    A second SO-110 B (Arnold et al., 2010) ion source was installed at the 6 MV CologneAMS for the measurement of gaseous samples. For the gas supply a dedicated device from Ionplus AG was connected to the ion source. Special effort was devoted to determine optimized operation parameters for the ion source, which give a high carbon current output and a high 14C- yield. The latter is essential in cases when only small samples are available. Additionally a modified immersion lens and modified target pieces were tested and the target position was optimized.

  2. 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.

  3. Groundwater dating by estimation of groundwater flow velocity and dissolved 4He accumulation rate calibrated by 36Cl in the Great Artesian Basin, Australia

    NASA Astrophysics Data System (ADS)

    Mahara, Y.; Habermehl, M. A.; Hasegawa, T.; Nakata, K.; Ransley, T. R.; Hatano, T.; Mizuochi, Y.; Kobayashi, H.; Ninomiya, A.; Senior, B. R.; Yasuda, H.; Ohta, T.

    2009-09-01

    We tested two methods for dating groundwaters that cannot be reliably measured by 36Cl dating alone, one based on groundwater flow velocity plus distance along a flow path and the other based on 4He accumulation rates calibrated with 36Cl dates. We sampled groundwaters along six inferred regional groundwater flow paths in the Great Artesian Basin (GAB) of Australia. We selected three groundwater paths where the decrease in 36Cl was largely controlled by cosmogenic 36Cl radioactive decay without a significant increase in chloride concentration. The extrapolated groundwater velocities were 0.133 ± 0.018 m/y to 0.433 ± 0.140 m/y. The estimated residence time of 1.06 × 10 6 y at the discharge area around Lake Eyre was comparable to the estimate of (1-2.2) × 10 6 y in previous studies. On the other hand, our estimated 4He accumulation rates for the selected three groundwater flow paths (1.85 ± 0.31 × 10 - 11 to 1.51 ± 0.63 × 10 - 10 ccSTP/cm 3•y) were approximately 2-15 times lower than previously reported rates for the central GAB. Our estimated rate of 1.51 × 10 - 10 ccSTP/cm 3•y - 1 in the western GAB is compatible with previous estimates based on 81Kr ages. The groundwater residence time estimated from the 4He accumulation rate was approximately 7 × 10 5 y near the discharge area at Lake Eyre. Finally, both estimations were mutually compatible with a 30% error.

  4. Dating chert using in-situ produced 10Be: Possible complications revealed on landslide scarps through a comparison with 36Cl applied to coexisting limestone.

    NASA Astrophysics Data System (ADS)

    Zerathe, Swann; Braucher, Régis; Lebourg, Thomas; Leani, Leatitia; Manetti, Michel; Bourles, Didier

    2013-04-01

    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 36Cl 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 36Cl within carbonate for samples originating from the same scarp. While 36Cl 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 36Cl counterparts. Because potential adsorption of 10Be at the surface of amorphous silica grains was suspected, partial dissolution

  5. Current achievements and challenges of a multiple dating approach (14C, 230Th/U and 36Cl) to infer tsunami transport age(s) of reef-top boulders on Bonaire (Leeward Antilles)

    NASA Astrophysics Data System (ADS)

    Rixhon, Gilles; May, Simon Matthias; Engel, Max; Mechernich, Silke; Schroeder-Ritzrau, Andrea; Frank, Norbert; Fohlmeister, Jens; Boulvain, Frédéric; Dunai, Tibor; Brückner, Helmut

    2017-04-01

    The deposition of supratidal coarse-clast deposits is difficult to date, limiting their value for inferring frequency-magnitude patterns of high-energy wave events. On Bonaire (Leeward Antilles, Caribbean), these deposits form prominent landforms, and transport by one or several Holocene tsunamis is assumed at least for the largest clasts. Although a large dataset of 14C and electron spin resonance (ESR) ages is available for major coral rubble ridges and ramparts, it is still debated whether these data reflect the timing of major events, and how these datasets are biased by the reworking of coral fragments. As an attempt to overcome the current challenges for dating the dislocation of singular boulders, three distinct dating methods are implemented and compared: (i) 14C dating of boring bivalves attached to the boulders; (ii) 230Th/U dating of post-depositional, secondary calcite flowstone and subaerial microbialites at the underside of the boulders; and (iii) surface exposure dating of overturned boulders via 36Cl concentration measurements in corals. Approaches (ii) and (iii) have never been applied to coastal boulder deposits so far. The three 14C age estimates are older than 37 ka, i.e. most probably beyond the applicability of the method, which is attributed to post-depositional diagenetic processes, shedding doubt on the usefulness of this method in the local context. The remarkably convergent 230Th/U ages, all pointing to the Late Holocene period (1.0-1.6 ka), are minimum ages for the transport event(s). The microbialite sample yields an age of 1.23±0.23 ka and both flowstone samples are in stratigraphic order: the older (onset of carbonate precipitation) and younger flowstone layers yield ages of 1.59±0.03 and 1.23±0.03 ka, respectively. Four coral samples collected from the topside of overturned boulders yielded similar 36Cl concentration measurements. However, the computed ages are affected by large uncertainties, mostly due to the high natural

  6. Plutonium AMS measurements in Yangtze River estuary sediment

    NASA Astrophysics Data System (ADS)

    Tims, S. G.; Pan, S. M.; Zhang, R.; Fifield, L. K.; Wang, Y. P.; Gao, J. H.

    2010-04-01

    The Yangtze River is the largest single source of sediment to the continental shelf of the East China Sea. The quantity of material exported by the river is expected to decrease substantially as a consequence of an extensive continuing program of dam construction within the river catchment. We report here AMS measurements of plutonium isotope concentrations and ratios for selected depth increments from a sediment core, collected from the sub-aqueous delta of the Yangtze River estuary. The Pu derives from atmospheric nuclear weapons testing in the 1950s and 1960s, and is potentially a useful tracer of sediment deposition times in the marine environment. The results show considerable structure in the depth-concentration profile, and offer an excellent opportunity to compare Pu with the more commonly used 137Cs isotopic tracer. The AMS data show superior sensitivity and indicate that the 240Pu/ 239Pu ratio can provide a check on the deposition dates. The changes in the 240Pu and 239Pu concentrations and the 240Pu/ 239Pu ratios with sediment depth all indicate the possibility of using Pu as a geochronological tool for coastal sediment studies.

  7. Dating Young Lava Flows with Cosmogenic 36Cl: AN Example from the Late Pleistocene - Early Holocene ERCİYES Monogenetic Lava Domes in Central Turkey

    NASA Astrophysics Data System (ADS)

    Akif Sarıkaya, M.; Çiner, Attila; Şen, Erdal; Ersoy, Orkun; Zreda, Marek

    2017-04-01

    measured 36Cl. If the nucleogenic components were set to zero, the average 36Cl ages of the three young lava flows would be 11.6±0.6 ka, 10.4±0.2 ka and 11.7±0.3 ka, respectively. In that case the 10.4±0.2 ka lava flow and radiocarbon dated (9.7± 0.2 ka) pyroclastic flow could be considered as contemporaneous. In order to measure the nucleogenic 36Cl directly, we drilled the older part of Çarık Lava flow at depths where the cosmic ray nucleon intensity would be negligible and taken the two deepest samples from the 9.3 m long core. When we corrected the Çarık Lava ages according to the measured nucleonic components, the ages became older (101.4±3.7 ka and 38.5±0.9 ka). The youngest previously dated volcanic deposit on Erciyes was on Çarık Lava flow (80±10 ky old, from a single 40Ar/39Ar age). Our findings indicate that Çarık has at least two separate lava flows and that the recent activity of Erciyes stratovolcano continued at least till Early Holocene.

  8. Towards a glacial chronology of the central Dinaric Alps using cosmogenic 36Cl dating

    NASA Astrophysics Data System (ADS)

    Žebre, Manja; Akif Sarıkaya, Mehmet; Stepišnik, Uroš; Yıldırım, Cengiz; Çiner, Attila

    2017-04-01

    Glacial chronology of the Dinaric Alps is largely understudied and therefore still not well-understood if compared with other Mediterranean mountains. Few attempts of dating glacial deposits have been made recently in the southern Dinaric Alps, suggesting at least four major glacial advances in the Late Quaternary. However, a more precise timeframe of glaciations in the Dinaric Alps is needed for a better understanding of the (a)synchrony of glacier advances in the Mediterranean during the Late Quaternary cold stage climates. The aim of this study is to reconstruct the glacial history of three carbonate mountain massifs in the central Dinaric Alps by means of geomorphological investigation and surface exposure dating of glacial boulders. Different generations of moraines and other glacial landforms in the Čvrsnica (2226 m), Velež (1969 m) and Crvanj (1920 m) Mountains in Bosnia and Herzegovina were mapped and used as morphometrical markers for estimating the extent and thickness of former glaciers. A peculiarity of the studied moraines is their magnitude in relation to the glacier`s hinterland and high preservation potential related to the karst environment with almost absent fluvial reworking. These well-preserved moraines hosting carbonate blocks on the crests are excellent sampling sites for cosmogenic 36Cl dating. Thirty-two boulders from some of the outermost hummocky, lateral and terminal moraines from the three mountains were sampled for cosmogenic 36Cl surface exposure dating. Analytical processes of these samples are still in progress.

  9. 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

  10. 47 CFR 73.154 - AM directional antenna partial proof of performance measurements.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false AM directional antenna partial proof of...) BROADCAST RADIO SERVICES RADIO BROADCAST SERVICES AM Broadcast Stations § 73.154 AM directional antenna... measurements are to be made within 3 to 15 kilometers from the center of the antenna array. When a...

  11. 47 CFR 73.154 - AM directional antenna partial proof of performance measurements.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 4 2014-10-01 2014-10-01 false AM directional antenna partial proof of...) BROADCAST RADIO SERVICES RADIO BROADCAST SERVICES AM Broadcast Stations § 73.154 AM directional antenna... measurements are to be made within 3 to 15 kilometers from the center of the antenna array. When a...

  12. 47 CFR 73.154 - AM directional antenna partial proof of performance measurements.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 4 2013-10-01 2013-10-01 false AM directional antenna partial proof of...) BROADCAST RADIO SERVICES RADIO BROADCAST SERVICES AM Broadcast Stations § 73.154 AM directional antenna... measurements are to be made within 3 to 15 kilometers from the center of the antenna array. When a...

  13. International-Aerial Measuring System (I-AMS) Training Program

    SciTech Connect

    Wasiolek, Piotre T.; Malchor, Russell L.; Maurer, Richard J.; Adams, Henry L.

    2015-10-01

    Since the Fukushima reactor accident in 2011, there has been an increased interest worldwide in developing national capabilities to rapidly map and assess ground contamination resulting from nuclear reactor accidents. The capability to rapidly measure the size of the contaminated area, determine the activity level, and identify the radionuclides can aid emergency managers and decision makers in providing timely protective action recommendations to the public and first responders. The development of an aerial detection capability requires interagency coordination to assemble the radiation experts, detection system operators, and aviation aircrews to conduct the aerial measurements, analyze and interpret the data, and provide technical assessments. The Office of International Emergency Management and Cooperation (IEMC) at the U.S. Department of Energy, National Nuclear Security Administration (DOE/NNSA) sponsors an International - Aerial Measuring System (I-AMS) training program for partner nations to develop and enhance their response to radiological emergencies. An initial series of courses can be conducted in the host country to assist in developing an aerial detection capability. As the capability develops and expands, additional experience can be gained through advanced courses with the opportunity to conduct aerial missions over a broad range of radiation environments.

  14. Sources and significance of variation in the dose estimates of 36Cl biosphere transfer models: a model intercomparison study.

    PubMed

    Bytwerk, D; Limer, L; Albrecht, A; Marang, L; Smith, G; Thorne, M

    2011-03-01

    A range of performance assessments have indicated that the long-lived activation product (36)Cl will be among the more significant contributors to dose following release to the biosphere from deep or near-surface repositories for radioactive wastes. Described here are results of a BIOPROTA model intercomparison study, investigating dose assessment uncertainties and variability on the basis of six (36)Cl models from three countries. The models share a compartmental approach with transfers between compartments handled on the basis of empirical transfer factors (IMARC, ERB2A, Aquabios), on the basis of defined specific activities (AquaCl36, SA_36Cl), or on a combination of these methods (MTA_Cl36). The dose estimates that these models produce for a consensus well-water irrigation scenario, as well as the effect of altering certain critical assumptions, are reported, and the causes of variation examined. For the scenario considered, the calculated doses are within a factor of 15 of each other. Major differences were attributable to the data used for stable Cl concentrations and (36)Cl transfer parameter values, both typically site-specific parameters. Additional critical assumptions were studied such as the impact of stable chloride in the diet on dose coefficients, the effect of irrigating pasture with contaminated water on (36)Cl concentrations in animal products, and the explicit consideration of foliar uptake.

  15. 50 CFR 640.28 - Annual catch limits (ACLs) and accountability measures (AMs).

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ..., NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE SPINY LOBSTER FISHERY OF THE GULF... accountability measures (AMs). For recreational and commercial spiny lobster landings combined, the ACL is...

  16. 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.

  17. 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.

  18. Late Pleistocene Glaciations in Zijovo Range, Montenegro; with 36Cl cosmogenic dating

    NASA Astrophysics Data System (ADS)

    Yesilyurt, S.; Petrovic, A. S.; Ivy-Ochs, S.; Vockenhuber, C.; Akçar, N.

    2016-12-01

    During cold periods of Pleistocene, the most part of Montenegro Mountains were glaciated. Recently, chronology of Late Quaternary advances in the northern Montenegro Mountains was reconstructed. However, glacier advances in the southeastern Montenegro Mountains remains undated. In this study we investigated paleoglaciations in Zijovo Range (2184 m) in order to reconstruct the chronology, and thus, the magnitude and frequency of glacier oscillations in south-eastern Montenegro during the Late Pleistocene. Zijovo Range is located in southeast of Montenegro on the Albania border, was covered by ice cap ca. 200 km2, and glacier tongues reaching down to ca. 800 m above modern sea level. Well-preserved glacial deposits are situated in the west part of the mountain. Lateral and terminal moraines of this part indicate several glacial advances. To build their chronology, 45 calcareous boulders in two valleys, Krzanja and Korita Kucka, were sampled for surface exposure dating with cosmogenic 36Cl. Krzanja valley is located on the western side of mountain and open to the west on the karst plateau. Lateral and terminal moraines of the valley end up ca. 1050 m. We collected 35 samples from the boulders on lateral and terminal moraine ridges of the valley. However, Korita Kucka valley is located on the southern part of the mountain, and glacial deposits are on the plateau ca. 1100 m. In this valley 10 samples were collected from the boulders on the terminal moraine ridges. First results will be then presented.

  19. In vivo measurement of /sup 241/Am in an accidentally exposed subject

    SciTech Connect

    Palmer, H.E.; Rieksts, G.A.; Icayan, E.E.

    1981-10-01

    Detailed external measurements were made of internally deposited /sup 241/Am in a nuclear chemical operator involved in an americium exposure accident at the Hanford plant. Despite some interference from high-level external contamination, quantitative measurements of the /sup 241/Am content in the lung, liver, and bones were made starting on the third day after the accident. The rate of excretion of /sup 241/Am from these organs was determined. The /sup 241/Am embedded in the skin of the face and head was carefully mapped. The distribution over the total length of the body was also determined. Linear and rectilinear scanners, gamma cameras, large and small scintillation detectors, proportional counters, and Si(Li) and intrinsic germanium detectors were used to evaluate the internal deposition. Methods of calibration for quantitative measurement included simulation of the /sup 241/Am activity in both phantom and cadaver parts.

  20. AMS beyond 2000

    SciTech Connect

    Davis, J.C.

    1993-12-28

    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 26}Al, {sup 36}Cl, 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.

  1. Interlaboratory study of the ion source memory effect in 36Cl accelerator mass spectrometry

    NASA Astrophysics Data System (ADS)

    Pavetich, Stefan; Akhmadaliev, Shavkat; Arnold, Maurice; Aumaître, Georges; Bourlès, Didier; Buchriegler, Josef; Golser, Robin; Keddadouche, Karim; Martschini, Martin; Merchel, Silke; Rugel, Georg; Steier, Peter

    2014-06-01

    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.

  2. Can-AMS: The New Accelerator Mass Spectrometry Facility At The University Of Ottawa

    SciTech Connect

    Kieser, W. E.; Zhao, X.-L.; Clark, I. D.; Kotzer, T.; Litherland, A. E.

    2011-06-01

    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 26}Al, {sup 36}Cl 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 36}Cl 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.

  3. Report on 241,242Am(n,x) surrogate cross section measurement

    SciTech Connect

    Burke, J T; Ressler, J J; Gostic, J; Henderson, R A; Bernstein, L A; Escher, J E; Bleuel, D; Kritcher, A; Matoon, C; Scielzo, N D; Stoyer, M A

    2011-02-16

    The main goal of this measurement is to determine the {sup 242}Am(n,f) and {sup 241}Am(n,f) cross sections via the surrogate {sup 243}Am. Gamma-ray data was also collected for the purpose of measuring the (n,2n) cross-sections. The experiment was conducted using the STARS/LIBERACE experimental facility located at the 88 Inch Cyclotron at Lawrence Berkeley National Laboratory the first week of February 2011. A description of the experiment and status of the data analysis follow.

  4. 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

  5. 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.

  6. Using the nuclear activation AMS method for determining chlorine in solids at ppb-levels and below

    NASA Astrophysics Data System (ADS)

    Winkler, Stephan R.; Eigl, Rosmarie; Forstner, Oliver; Martschini, Martin; Steier, Peter; Sterba, Johannes H.; Golser, Robin

    2015-10-01

    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 36Cl: 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 36Cl-AMS setup at the Vienna Environmental Research Accelerator (VERA) was used for 36Cl/Cl analysis.

  7. Translocation of (125)I, (75)Se and (36)Cl to edible parts of radish, potato and green bean following wet foliar contamination under field conditions.

    PubMed

    Henner, P; Hurtevent, P; Thiry, Y; Levchuk, S; Yoschenko, V; Kashparov, V

    2013-10-01

    Specific translocation factor values (ftr) for (129)I, (79)Se and (36)Cl following foliar transfer are still missing from the IAEA reference databases. The translocation of the short-lived isotopes, (125)I, (75)Se, and (36)Cl, 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 (36)Cl 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

  8. The Am-243 Neutron Capture Measurement at the n_TOF Facility

    NASA Astrophysics Data System (ADS)

    Mendoza, E.; Cano-Ott, D.; Guerrero, C.; Álvarez-Velarde, F.; García-Ríos, A.; González-Romero, E.; Martínez, T.; Villamarin, D.; Kadi, Y.; Colonna, N.; Marrone, S.; Meaze, M. H.; Tagliente, G.; Terlizzi, R.; Abbondanno, U.; Belloni, F.; Fujii, K.; Milazzo, P. M.; Moreau, C.; Andriamonje, S.; Calviani, M.; Vlachoudis, V.; Chiaveri, E.; Andrzejewski, J.; Marganiec, J.; Assimakopoulos, P.; Karadimos, D.; Karamanis, D.; Papachristodoulou, C.; Patronis, N.; Audouin, L.; David, S.; Ferrant, L.; Isaev, S.; Stephan, C.; Tassan-Got, L.; Badurek, G.; Jericha, E.; Leeb, H.; Oberhummer, H.; Pigni, M. T.; Poch, A.; Baumann, P.; Kerveno, M.; Lukic, S.; Rudolf, G.; Becvar, F.; Krticka, M.; Calvino, F.; Capote, R.; Frais-Koelbl, H.; Griesmayer, E.; Mengoni, A.; Lozano, M.; Quesada, J. M.; Carrillo de Albornoz, A.; Tavora, L.; Marques, L.; Salgado, J.; Vaz, P.; Cennini, P.; Dahlfors, M.; Ferrari, A.; Gramegna, F.; Herrera-Martinez, A.; Mastinu, P.; Praena, J.; Sarchiapone, L.; Wendler, H.; Chepel, V.; Ferreira-Marques, R.; Goncalves, I.; Lindote, A.; Lopes, I.; Neves, F.; Berthoumieux, E.; Dridi, W.; Gunsing, F.; Aerts, G.; Pancin, J.; Perrot, L.; Plukis, A.; Cortes, G.; Pretel, C.; Couture, A. J.; Cox, J.; O'Brien, S.; Wiescher, M.; Dillman, I.; Heil, M.; Käppeler, F.; Mosconi, M.; Plag, R.; Voss, F.; Walter, S.; Wisshak, K.; Dolfini, R.; Rubbia, C.; Domingo Pardo, C.; Tain, J. L.; Eleftheriadis, C.; Lampoudis, C.; Savvidis, I.; Furman, W.; Konovalov, V.; Goverdovski, A.; Ketlerov, V.; Duran, I.; Paradela, C.; Álvarez, H.; Haas, B.; Haight, R.; Reifarth, R.; Igashira, M.; Koehler, P.; Kossionides, E.; Massimi, C.; Vannini, G.; Oshima, M.; Papadopoulos, C.; Vlastou, R.; Pavlik, A.; Pavlopoulos, P.; Plompen, A.; Rullhusen, P.; Rauscher, T.; Rosetti, M.; Ventura, A.

    2013-03-01

    The 243Am neutron capture cross section has been measured at the n_TOF facility1 in the 0.7 eV-2 keV energy range. The n_TOF Total Absorption Calorimeter2 (TAC) composed by 40 BaF2 crystals has been used in the measurement for detecting the electromagnetic cascades produced in the 243Am(n, γ) reactions. All current evaluations in the resolved resonance region are based essentially in fission measurements and in only one transmission measurement.3 The analysis of the measurement has been finished recently, and it is ready for its distribution to the EXFOR nuclear database. In addition, the data obtained with the TAC provide valuable information on the level density in the compound nucleus 244Am and on its electromagnetic de-excitation scheme. In particular, the 243Am data will be combined with data from previous measurements of 241Am, 240Pu, 237Np and 233,234,236U and with future measurements of 235,238U for a systematic investigation of the photon strength functions in actinides.

  9. Plutonium measurements on the 1 MV AMS system at the Centro Nacional de Aceleradores (CNA)

    NASA Astrophysics Data System (ADS)

    Chamizo, Elena; Enamorado, Santiago Miguel; García-León, Manuel; Suter, Martin; Wacker, Lukas

    2008-11-01

    Plutonium isotopes have been recently added to the list of radionuclides that can be measured with the new generation of compact AMS facilities. In this paper we present first experimental results concerning the development of the plutonium AMS technique at 680 kV on the 1 MV AMS system at the Centro Nacional de Aceleradores (CNA) in Sevilla, Spain. This is the first compact AMS machine designed and manufactured by High Voltage Engineering Europa. As we demonstrate, the obtained backgrounds for 239,240Pu, of about 10 6 atoms, and the 239Pu/ 238U mass suppression factor, in the range of 10 -9, compare to the ones achieved on other AMS facilities. With the measurement of reference materials provided by the International Atomic Energy Agency (IAEA-375, IAEA-Soil-6, IAEA-381) and samples already studied on the 600 kV compact ETH/PSI AMS system at Zürich, we show that the CNA system can be perfectly used for the routine measurement of plutonium isotopes at environmental levels.

  10. AMS-02 Capabilities in Solar Energetic Particle Measurements for Space Weather Physics

    NASA Astrophysics Data System (ADS)

    Consolandi, Cristina; Bindi, Veronica; Corti, Claudio; Hoffman, Julia; Whitman, Kathryn

    2016-04-01

    The Alpha Magnetic Spectrometer (AMS-02), thanks to its large acceptance of about 0.45 m2 sr, is the biggest Solar Energetic Particle (SEP) detector ever flown in space. AMS-02 was installed on the International Space Station (ISS) on May 19, 2011, where it will measure cosmic rays from 1 GV up to a few TV, for the duration of the ISS, currently extended till 2024. During these years of operation, AMS-02 measured several increases of the protons flux over the Galactic Cosmic Ray (GCR) background associated to the strongest solar events. AMS-02 has observed the related SEP accelerated during M- and X-class flares and fast coronal mass ejections measuring an increase of the proton flux near 1 GV and above. Some of these solar events were also followed by the typical GCR suppression i.e. Forbush decrease, which makes even more evident the measurement of the SEP flux over the GCR background. Thanks to its large acceptance and particle detection capabilities, AMS-02 is able to perform precise measurements in a short period of time which is typical of these transient phenomena and to collect enough statistics to measure fine structures and time evolution of particle spectra. The events observed by AMS-02 since the beginning of its mission will be presented and some of the more interesting events will be shown. AMS-02 observations with their unprecedented resolution and high statistics, will improve the understanding of SEP behavior at high energies to constrain models of SEP production used in space weather physics.

  11. The AMS Measurements and Its Applications in Nuclear Physics at China Institute of Atomic Energy (CIAE)

    SciTech Connect

    Jiang Shan; Shen Hongtao; He Ming; Dong Kejun; He Guozhu; Wang Xianggao; Yuan Jian; Wang Wei; Wu Shaoyong; Ruan Xiangdong; Wu Weimin

    2010-05-12

    Accelerator Mass Spectrometry (AMS), initiated in late 1970s at McMaster university based on the accelerator and detector technique, has long been applied in the studies on archaeology, geology, and cosmology, as a powerful tool for isotope dating. The advantages of AMS in the analysis of rare nuclides by direct counting of the atoms, small sample size and relatively free from the interferences of molecular ions have been well documented. This paper emphasizes that AMS can not only be used for archaeology, geology, environment, biology and so on, but also served as a unique tool for nuclear physics research. In this paper, the determination of the half-lives of {sup 79}Se, the measurements of the cross-sections of {sup 93}Nb(n,2n){sup 92g}Nb and {sup 238}U(n,3n){sup 236}U reactions, the detection and determination of ultratrace impurities in neutrino detector materials, and the measurement of the fission product nuclide {sup 126}Sn, are to be introduced, as some of examples of AMS applications in nuclear research conducted in AMS lab of China Institute of Atomic Energy. Searching for superheavy nuclides by using AMS is being planned.

  12. The AMS Measurements and Its Applications in Nuclear Physics at China Institute of Atomic Energy (CIAE)

    NASA Astrophysics Data System (ADS)

    Jiang, Shan; Shen, Hongtao; He, Ming; Ruan, Xiangdong; Wu, Weimin; Dong, Kejun; He, Guozhu; Wang, Xianggao; Yuan, Jian; Wang, Wei; Wu, Shaoyong

    2010-05-01

    Accelerator Mass Spectrometry (AMS), initiated in late 1970s at McMaster university based on the accelerator and detector technique, has long been applied in the studies on archaeology, geology, and cosmology, as a powerful tool for isotope dating. The advantages of AMS in the analysis of rare nuclides by direct counting of the atoms, small sample size and relatively free from the interferences of molecular ions have been well documented. This paper emphasizes that AMS can not only be used for archaeology, geology, environment, biology and so on, but also served as a unique tool for nuclear physics research. In this paper, the determination of the half-lives of 79Se, the measurements of the cross-sections of 93Nb(n,2n)92gNb and 238U(n,3n)236U reactions, the detection and determination of ultratrace impurities in neutrino detector materials, and the measurement of the fission product nuclide 126Sn, are to be introduced, as some of examples of AMS applications in nuclear research conducted in AMS lab of China Institute of Atomic Energy. Searching for superheavy nuclides by using AMS is being planned.

  13. Bonner sphere measurements of 241Am-B and 241Am-F neutron energy spectra unfolded using high-resolution a priori data.

    PubMed

    Roberts, N J; Jones, L N; Liu, Z Z; Tagziria, H; Thomas, D J

    2014-10-01

    High-resolution neutron energy spectra, covering the entire energy range of interest, for two standard radionuclide neutron sources ((241)Am-B and (241)Am-F) have been derived from Bonner sphere measurements by using high-resolution a priori data in the unfolding process. In each case, two a priori spectra were used, one from a two-stage calculation and also one from a combination of the calculated spectrum with a high-resolution measured spectrum. The unfolded spectra are compared with those published elsewhere and show significant differences from the ISO- and IAEA-recommended spectra for (241)Am-B and (241)Am-F, respectively. Values for the fluence-average energy and fluence-to-dose-equivalent conversion coefficients are presented for the new spectra, and the implications of the new spectra for the emission rates of the sources when measured by the manganese bath technique are also determined. © Crown copyright 2013.

  14. In vivo measurement of 241Am in the lungs confounded by activity deposited in other organs.

    PubMed

    Lobaugh, Megan L; Spitz, Henry B; Glover, Samuel E

    2015-01-01

    Radioactive material deposited in multiple organs of the body is likely to confound a result of an in vivo measurement performed over the lungs, the most frequently monitored organ for occupational exposure. The significance of this interference was evaluated by measuring anthropometric torso phantoms containing lungs, liver, skeleton, and axillary lymph nodes, each with a precisely known quantity of 241Am uniformly distributed in the organs. Arrays of multiple high-resolution germanium detectors were positioned over organs within the torso phantom containing 241Am or over proximal organs without activity to determine the degree of measurement confounding due to photons emitted from other source organs. A set of four mathematical response functions describes the measured count rate with detectors positioned over each of the relevant organs and 241Am contained in the measured organ or one of the other organs selected as a confounder. Simultaneous solution of these equations by matrix algebra, where the diagonal terms of the matrix are calibration factors for a direct measurement of activity in an organ and the off-diagonal terms reflect the contribution (i.e., interference or cross-talk) produced by 241Am in a confounding organ, yields the activity deposited in each of the relevant organs. The matrix solution described in this paper represents a method for adjusting a result of 241Am measured directly in one organ for interferences that may arise from 241Am deposited elsewhere and represents a technically valid procedure to aid in evaluating internal dose based upon in vivo measurements for those radioactive materials known to deposit in multiple organs.

  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. 50 CFR 622.49 - Annual catch limits (ACLs) and accountability measures (AMs).

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 50 Wildlife and Fisheries 12 2012-10-01 2012-10-01 false Annual catch limits (ACLs) and accountability measures (AMs). 622.49 Section 622.49 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE FISHERIES OF THE CARIBBEAN, GULF, AND SOUTH ATLANTIC Management Measures §...

  17. 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

  18. The use of AMS to the biomedical sciences

    SciTech Connect

    Vogel, J.S.

    1991-04-01

    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 36}Cl, {sup 79}SE, {sup 41}Ca, {sup 26}Al 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.

  19. Report on 240Am(n,x) surrogate cross section test measurement

    SciTech Connect

    Ressler, J J; Burke, J T; Gostic, J; Bleuel, D; Escher, J E; Henderson, R A; Koglin, J; Reed, T; Scielzo, N D; Stoyer, M A

    2012-02-01

    The main goal of the test measurement was to determine the feasibility of the {sup 243}Am(p,t) reaction as a surrogate for {sup 240}Am(n,f). No data cross section data exists for neutron induced reactions on {sup 240}Am; the half-life of this isotope is only 2.1 days making direct measurements difficult, if not impossible. The 48-hour experiment was conducted using the STARS/LIBERACE experimental facility located at the 88 Inch Cyclotron at Lawrence Berkeley National Laboratory in August 2011. A description of the experiment and results is given. The beam energy was initially chosen to be 39 MeV in order to measure an equivalent neutron energy range from 0 to 20 MeV. However, the proton beam was not stopped in the farady cup and the beam was deposited in the surrounding shielding material. The shielding material was not conductive, and a beam current, needed for proper tuning of the beam as well as experimental monitoring, could not be read. If the {sup 240}Am(n,f) surrogate experiment is to be run at LBNL, simple modifications to the beam collection site will need to be made. The beam energy was reduced to 29 MeV, which was within an energy regime of prior experiments and tuning conditions at STARS/LIBERACE. At this energy, the beam current was successfully tuned and measured. At 29 MeV, data was collected with both the {sup 243}Am and {sup 238}U targets. An example particle identification plot is shown in Fig. 1. The triton-fission coincidence rate for the {sup 243}Am target and {sup 238}U target were measured. Coincidence rates of 0.0233(1) cps and 0.150(6) cps were observed for the {sup 243}Am and {sup 238}U targets, respectively. The difference in count rate is largely attributed to the available target material - the {sup 238}U target contains approximately 7 times more atoms than the {sup 243}Am. A proton beam current of {approx}0.7 nA was used for measurements on both targets. Assuming a full experimental run under similar conditions, an estimate for the

  20. AMS Ground Truth Measurements: Calibration and Test Lines

    SciTech Connect

    Wasiolek, P.

    2013-11-01

    Airborne gamma spectrometry is one of the primary techniques used to define the extent of ground contamination after a radiological incident. Its usefulness was demonstrated extensively during the response to the Fukushima nuclear power plant (NPP) accident in March-May 2011. To map ground contamination a set of scintillation detectors is mounted on an airborne platform (airplane or helicopter) and flown over contaminated areas. The acquisition system collects spectral information together with the aircraft position and altitude every second. To provide useful information to decision makers, the count rate data expressed in counts per second (cps) needs to be converted to the terrestrial component of the exposure rate 1 m above ground, or surface activity of isotopes of concern. This is done using conversion coefficients derived from calibration flights. During a large scale radiological event, multiple flights may be necessary and may require use of assets from different agencies. However, as the production of a single, consistent map product depicting the ground contamination is the primary goal, it is critical to establish very early into the event a common calibration line. Such a line should be flown periodically in order to normalize data collected from different aerial acquisition systems and potentially flown at different flight altitudes and speeds. In order to verify and validate individual aerial systems, the calibration line needs to be characterized in terms of ground truth measurements. This is especially important if the contamination is due to short-lived radionuclides. The process of establishing such a line, as well as necessary ground truth measurements, is described in this document.

  1. 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

  2. Progress in AMS measurement of U isotope ratios in nanogram U samples

    NASA Astrophysics Data System (ADS)

    Dong, Kejun; He, Ming; Wang, Chen; Zhao, Xinhong; Li, Lili; Zhao, Yonggang; Wang, Xianggao; Shen, Hongtao; Wang, Xiaoming; Pang, Fangfang; Xu, Yongning; Zhao, Qingzhang; Dou, Liang; Yang, Xuran; Wu, Shaoyong; Lin, Deyu; Li, Kangning; You, Qubo; Bao, Yiwen; Hu, Yueming; Xia, Qingliang; Yin, Xinyi; Jiang, Shan

    2015-10-01

    The determination of uranium isotopic composition in ultra-trace U samples is very important in different fields, especially for the nuclear forensics. A new Accelerator Mass Spectrometry (AMS) technique has been developed for the measurement of uranium isotopic ratios in ng level uranium samples at China Institute of Atomic Energy (CIAE). Recently, the method was further optimized and developed by using a series of blank and standard samples. The results show that the 236U at the femtogram level can be determined in nanogram U samples by the newly developed AMS technique at CIAE. The experimental setup, performances and results will be detailed in this contribution.

  3. 50 CFR 622.280 - Annual catch limits (ACLs) and accountability measures (AMs).

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... MEXICO, AND SOUTH ATLANTIC Dolphin and Wahoo Fishery Off the Atlantic States § 622.280 Annual catch limits (ACLs) and accountability measures (AMs). (a) Atlantic dolphin—(1) Commercial sector. If commercial landings for Atlantic dolphin, as estimated by the SRD, reach or are projected to reach...

  4. 50 CFR 622.280 - Annual catch limits (ACLs) and accountability measures (AMs).

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... MEXICO, AND SOUTH ATLANTIC Dolphin and Wahoo Fishery Off the Atlantic States § 622.280 Annual catch limits (ACLs) and accountability measures (AMs). (a) Atlantic dolphin—(1) Commercial sector. (i) If commercial landings for Atlantic dolphin, as estimated by the SRD, reach or are projected to reach...

  5. Optimization of a ΔE - E detector for 41Ca AMS

    NASA Astrophysics Data System (ADS)

    Hosoya, Seiji; Sasa, Kimikazu; Matsunaka, Tetsuya; Takahashi, Tsutomu; Matsumura, Masumi; Matsumura, Hiroshi; Sundquist, Mark; Stodola, Mark; Sueki, Keisuke

    2017-09-01

    A series of nuclides (14C, 26Al, and 36Cl) was measured using the 12UD Pelletron tandem accelerator before replacement by the horizontal 6 MV tandem accelerator at the University of Tsukuba Tandem Accelerator Complex (UTTAC). This paper considers the modification of the accelerator mass spectrometry (AMS) measurement parameters to suit the current 6 MV tandem accelerator setup (e.g., terminal voltage, detected ion charge state, gas pressure, and entrance window material in detector). The Particle and Heavy Ion Transport code System (PHITS) was also used to simulate AMS measurement to determine the best conditions to suppress isobaric interference. The spectra of 41Ca and 41K were then successfully separated and their nuclear spectra were identified; the system achieved a background level of 41Ca/40Ca ∼ 6 ×10-14 .

  6. 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.

  7. AMS measurement of 53Mn and its initial application at CIAE

    NASA Astrophysics Data System (ADS)

    Dong, Kejun; Zhou, Duo; Xu, Yongning; He, Ming; Liu, Guangshan; Hu, Hao; Dou, Liang; Liu, Jiancheng; Wu, Shaoyong; Wang, Xianggao; Shen, Hongtao; Li, Kangning; You, Qubo; Bao, Yiwen; Hu, Yueming; Jin, Chunsheng; Yin, Xinyi; Jiang, Shan

    2015-10-01

    The determination of cosmogenic 53Mn in terrestrial archives has important applications, such as burial ages, exposure age and erosion rates. Accelerator mass spectrometry (AMS) is the most sensitive technique to detect minute amounts of 53Mn. 53Mn measurements were developed at the China Institute of Atomic Energy (CIAE) using the ΔE-Q3D equipped AMS system. This approach was recently optimized with the goal to reach the sensitivity required for AMS measurements of 53Mn in deep-sea ferromanganese crust (DSFC) samples. Based on these improvements of sample preparation, current beam transmission and so on, 53Mn in two samples of DSFC was measured by AMS. The ratios of 53Mn/Mn corresponding to an age of 3.77 ± 0.42 and 13.73 ± 2.74 Ma by 129I dating method are (5.01 ± 2.15) × 10-13 and (1.90 ± 0.96) × 10-13. The ratios are close to the experimental reference values, deduced from the previous research. The experimental progress, performances and results are presented in this contribution.

  8. Precise measurement of cosmic ray fluxes with the AMS-02 experiment

    SciTech Connect

    Vecchi, Manuela

    2015-12-17

    The AMS-02 detector is a large acceptance magnetic spectrometer operating onboard the International Space Station since May 2011. The main goals of the detector are the search for antimatter and dark matter in space, as well as the measurement of cosmic ray composition and flux. In this document we present precise measurements of cosmic ray positrons, electrons and protons, collected during the first 30 months of operations.

  9. The effect of AM noise on correlation phase-noise measurements.

    PubMed

    Rubiola, Enrico; Boudot, Rodolphe

    2007-05-01

    We analyze the phase-noise measurement methods in which correlation and averaging is used to reject the background noise of the instrument. All the known methods make use of a mixer, used either as a saturated-phase detector or as a linear-synchronous detector. Unifortunately, AM noise is taken in through the power-to-dc-offset conversion mechanism that results from the mixer asymmetry. The measurement of some mixers indicates that the unwanted amplitude-to-voltage gain is of the order of 5-50 mV, which is 12-35 dB lower than the phase-to-voltage gain of the mixer. In addition, the trick of setting the mixer at a sweet point--off the quadrature condition--where the sensitivity to AM nulls, works only with microwave mixers. The HF-VHF mixers do not have this sweet point. Moreover, we prove that if the AM noise comes from the oscillator under test, it cannot be rejected by correlation. At least not with the schemes currently used. An example shows that at some critical frequencies the unwanted effect of AM noise is of the same order-if not greater--than the phase noise. Thus, experimental mistakes are around the corner.

  10. Large Earthquake Repeat on Normal Faults: Insights from dense in-situ 36Cl Exposure Dating of Limestone Fault Scarps, Central Apennines, Italy

    NASA Astrophysics Data System (ADS)

    Schlagenhauf, A.; Benedetti, L.; Manighetti, I.

    2007-12-01

    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 36Cl 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

  11. 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.

  12. Glacial and volcanic evolution on Nevado Coropuna (Tropical Andes) based on cosmogenic 36Cl surface exposure dating

    NASA Astrophysics Data System (ADS)

    Úbeda, J.; Palacios, D.; Vázquez-Selém, L.

    2012-04-01

    We have reconstructed the evolution of the paleo-glaciers of the volcanic complex Nevado Coropuna (15°S, 72°W; 6377 m asl) through the interpretation and dating of geomorphological evidences. Surface exposure dating (SED) based on the accumulation of 36Cl on the surface of moraine boulders, polished bedrock and lava flows allowed: 1) to confirm that the presence of ice masses in the region dates back to >80ka; 2) to produce chronologies of glacial and volcanic phases for the last ~21 ka; and 3) to obtain evidences of the reactivation of volcanic activity after the Last Glacial Maximum. Bromley et al. (2009) presented 3He SED ages of 21 ka for moraine boulders on the Mapa Mayo valley, to the North of Nevado Coropuna. Our 36Cl SED SED for moraine boulders from the valleys on the NE sector of the volcanic complex suggest a maximum initial advance between 20 and 16 ka, followed by another expansion of similar extent at 12-11 ka. On the Southern slope of Nevado Coropuna, the 36Cl ages show a maximum initial advance that reaches to the level of the Altiplano at 14 ka, and a re-advance at ~10-9 ka BP. Other data show minor re-advances at 9 ka on the Northern slope and at 6 ka to the South of the volcanic complex. These minor positive pulses interrupted a fast deglaciation process during the Holocene as shown by two series of 36Cl SED from polished rock surfaces on successively higher altitudes along the valleys of rivers Blanco and Cospanja, to the SW and SE. Despite the global warming occuring since 20 ka, deduced from the record of sea surface paleo-temperature of the Galapago Islands (Lea et al, 2006), the evolution of the fresh-water plankton from Lake Titicaca (Fritz et al, 2007) is consistent with sustained glacial conditions until 10-9 ka as suggested by the present work. Exposure ages of three lava flows indicate a reactivation of the magmatic system as the paleo-glaciers abandonned the slopes. The eruptive activity migrated from the West, where we found a lava

  13. Precision measurements of nuclear CR energy spectra and composition with the AMS-02 experiment

    NASA Astrophysics Data System (ADS)

    Fiandrini, E.

    2016-05-01

    The Alpha Magnetic Spectrometer 02 (AMS-02) is a large acceptance high-energy physics experiment operating since May 2011 on board the International Space Station. More than 60 billion events have been collected by the instrument in the first four years of operation. AMS-02 offers a unique opportunity to study the Cosmic Rays (CRs) since it measures the spectra of all the species simultaneously. We report on the precision measurements of primary and secondary nuclear spectra, in the GeV-TeV energy interval. These measurements allow for the first time a detailed study of the spectral index variation with rigidity providing a new insight on the origin and propagation of CR.

  14. 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.

  15. Ultra-separation of nickel from copper metal for the measurement of 63Ni by AMS

    NASA Astrophysics Data System (ADS)

    Marchetti, A. A.; Hainsworth, L. J.; McAninch, J. E.; Leivers, M. R.; Jones, P. R.; Proctor, I. D.; Straume, T.

    1997-03-01

    Measurements of 63Ni (t{1}/{2} = 100 yr) produced by the reaction 63Cu(n,p)63Ni could be used in the assessment of fast-neutron fluence from the Hiroshima atomic bomb. Such measurements would add new information to help resolve the current discrepancy between measured thermal neutron activation values and those calculated with the DS86 dosimetry system. It has been estimated that the 63Ni production at 5 m from the hypocenter was (1.4 ± 0.1) × 107 atoms/g Cu. Because of its sensitivity, accelerator mass spectrometry (AMS) is ideal for measurements at this low level. However, 63Ni has to be separated from large amounts of stable atomic isobar 63Cu (69% of pure Cu). In this study, a procedure is presented for the electrochemical separation of ultra-low amounts of Ni from Cu. The method was developed using samples of electrical Cu wire that were irradiated with fission neutrons from a 252Cf source. The wire samples were electrochemically dissolved in a solution containing 1 mg of Ni carrier. The Cu was selectively deposited on a cathode at controlled potential. Measurements of total Ni after electroseparation indicate ˜ 100% carrier recovery. To prevent Cu contamination, AMS targets were prepared by nickel carbonyl generation. The AMS results show a successful quantitative separation of ˜ 107 atoms of 63Ni from 2-20 g samples of Cu.

  16. 50 CFR 622.58 - Annual catch limits (ACLs), annual catch targets (ACTs), and accountability measures (AMs).

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 50 Wildlife and Fisheries 12 2014-10-01 2014-10-01 false Annual catch limits (ACLs), annual catch targets (ACTs), and accountability measures (AMs). 622.58 Section 622.58 Wildlife and Fisheries FISHERY... Annual catch limits (ACLs), annual catch targets (ACTs), and accountability measures (AMs). (a) Royal...

  17. 50 CFR 622.58 - Annual catch limits (ACLs), annual catch targets (ACTs), and accountability measures (AMs).

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 50 Wildlife and Fisheries 12 2013-10-01 2013-10-01 false Annual catch limits (ACLs), annual catch targets (ACTs), and accountability measures (AMs). 622.58 Section 622.58 Wildlife and Fisheries FISHERY... Annual catch limits (ACLs), annual catch targets (ACTs), and accountability measures (AMs). (a) Royal...

  18. Cosmogenic 10Be and 36Cl geochronology of offset alluvial fans along the northern Death Valley fault zone: Implications for transient strain in the eastern California shear zone

    USGS Publications Warehouse

    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.

    2007-01-01

    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 36Cl 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 36Cl 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.

  19. Modelling of Earthquake History of the Knidos Fault Zone SW Turkey Using in-situ 36Cl Surface Exposure Dating by R

    NASA Astrophysics Data System (ADS)

    Sahin, S.; Yıldırım, C.; Sarıkaya, M. A.; Tuysuz, O.; Genç, S. C.; Aksoy, M. E.; Doksanaltı, M. E.; Benedetti, L.

    2016-12-01

    Cosmogenic surface exposure dating is based on the production of rare nuclides in exposed rocks, which interact with cosmic rays. Through modelling of measured 36Cl 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 fault, topography, geographic location of study area, temporal variations of the Earth's magnetic field, self-cover and denudation rate on the scarp. Our study area, the Knidos Fault Zone, is located on the Datça Peninsula in the Southwestern Anatolia and contains several normal fault scarps formed within the limestone, which are appropriate to apply cosmogenic chlorine-36 dating. 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 36Cl isotopes concentrations. Recent research elucidated each step of the application of this method by the Matlab (e.g. Schlagenhauf et al., 2010). It is vitally helpful to generate models activity of normal faults. We, however, wanted to build a user-friendly program through an open source programing language R that might be able to help those without knowledge of complex math, programming, making calculations as easy as possible. We have set out to obtain accurate conclusions to compare and contrast our results with synthetic profiles and previous studies of limestone fault scarps. The preliminary results indicate at least three major or more earthquakes/earthquakes cluster events occurred on the Mezarlık fault within the past 20 kyr; over 10 meters of displacement took place between early Holocene and late Pleistocene. Estimated ages of those three large slip events are 18.7, 15.1 and 10.8 ka respectively. This study was conducted with the Decision of the Council of Ministers with No

  20. Three time scales of earthquake clustering inferred from in-situ 36Cl cosmogenic dating on the Velino-Magnola fault (Central Italy)

    NASA Astrophysics Data System (ADS)

    Schlagenhauf, A.; Manighetti, I.; Benedetti, L.; Gaudemer, Y.; Malavieille, J.; Finkel, R. C.; Pou, K.

    2010-12-01

    Using in-situ 36Cl 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 36Cl 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

  1. Surrogate measurements of the 241,242Am (n,f) cross sections

    NASA Astrophysics Data System (ADS)

    Ressler, J. J.; Burke, J. T.; Escher, J. E.; Adekola, A.; Austin, R. E. A.; Basunia, M. S.; Beausang, C. W.; Bernstein, L. A.; Bleuel, D.; Gostic, J.; Henderson, R. H.; Hughes, R. O.; Hurst, A.; Kritcher, A.; Mattoon, C. M.; Munson, J.; Phair, L. W.; Ross, T.; Scielzo, N. D.; Stoyer, M. A.

    2011-10-01

    New reactor designs and materials, reprocessing efforts, and transmutation of nuclear waste play significant roles in the future of nuclear energy. New or improved neutron measurements on a number of isotopes are needed to determine feasibility, effectiveness, and safety issues for the novel engineering efforts. Data collection is often hampered by the need for radioactive targets; the use of such targets is limited to longer-lived isotopes due to the large background induced by the decay of the material. However, cross sections for isotopes of interest can be obtained indirectly using light-ion reactions on long-lived neighbors. Decay from the compound state is assumed to be independent of the production reaction, allowing reactions with the neighboring isotopes to be used as a surrogate for the reaction of interest. Results from the neutron-induced fission cross sections of 241Am and 242Am, performed via surrogates 243Am(3He, α' f) and 243Am(3He, 3He' f), respectively, will be shown. This work was performed under the auspices of the U.S. DOE by LLNL under contract DE-AC52-07NA27344.

  2. Improving the method of low-temperature anisotropy of magnetic susceptibility (LT-AMS) measurements in air

    NASA Astrophysics Data System (ADS)

    Issachar, R.; Levi, T.; Lyakhovsky, V.; Marco, S.; Weinberger, R.

    2016-07-01

    This study examines the limitations of the method of low-temperature anisotropy of magnetic susceptibility (LT-AMS) measurements in air and presents technical improvements that significantly reduce the instrumental drift and measurement errors. We analyzed the temperature profile of porous chalk core after cooling in liquid nitrogen and found that the average temperature of the sample during the LT-AMS measurement in air is higher than 77K and close to 92K. This analysis indicates that the susceptibility of the paramagnetic minerals are amplified by a factor ˜3.2 relative to that of room temperature AMS (RT-AMS). In addition, it was found that liquid nitrogen was absorbed in the samples during immersing and contributed diamagnetic component of ˜-9 × 10-6 SI to the total mean susceptibility. We showed that silicone sheet placed around and at the bottom of the measuring coil is an effective thermal protection, preventing instrument drift by the cold sample. In this way, the measuring errors of LT-AMS reduced to the level of RT-AMS, allowing accurate comparison with standard AMS measurements. We examined the applicability of the LT-AMS measurements on chalk samples that consist <5% (weight) of paramagnetic minerals and showed that it helps to efficiently enhance the paramagnetic fabric. The present study offers a practical approach, which can be applied to various types of rocks to better delineate the paramagnetic phase using conventional equipment.

  3. Development of algorithm for retrieving aerosols over land surfaces from NEMO-AM polarized measurements

    NASA Astrophysics Data System (ADS)

    Pandya, Mehul R.

    2016-04-01

    Atmospheric aerosols have a large effect on the Earth radiation budget through its direct and indirect effects. A systematic assessment of aerosol effects on Earth's climate requires global mapping of tropospheric aerosols through satellite remote sensing. However aerosol retrieval over land surface remains a challenging task due to bright background of the land surfaces. Polarized measurements can provide an improved aerosol sensing by providing a means of decoupling the surface and atmospheric contribution. The Indian Space Research Organisation has planned a Multi- Angle Dual-Polarization Instrument (MADPI) onboard a Nano satellite for Earth Monitoring & Observations for Aerosol Monitoring (NEMO-AM). MADPI has three spectral bands in blue, red and near infrared spectral regions with a nominal spatial resolution of 30 m from an altitude of 500 km polar orbit. A study has been taken up with the aim of development of an algorithm for retrieving aerosol optical thickness (AOT) over land surfaces from NEMO-AM polarized measurements. The study has three major components: (1) detailed theoretical modelling exercise for computing the atmospheric and surface polarized contributions, (2) modelling of total satellite-level polarized contribution, and (3) retrieval of aerosol optical thickness (AOT) by comparing the modelled and measured polarized signals. The algorithm has been developed for MADPI/NEMO-AM spectral bands and tested successfully on similar spectral bands of POLDER/PARASOL measurements to retrieve AOT over Indian landmass having diverse atmospheric conditions. POLDER-derived AOT fields were compared with MODIS-AOT products. Results showed a very good match (R2 0.69, RMSE 0.07). Initial results have provided encouraging results, however, comprehensive analysis and testing has to be carried out for establishing the proposed algorithm for retrieving AOT from NEMO-AM measurements.

  4. Measurement of the Am242m neutron-induced reaction cross sections

    DOE PAGES

    Buckner, M. Q.; Wu, C. Y.; Henderson, R. A.; ...

    2017-02-17

    The neutron-induced reaction cross sections of 242mAm were measured at the Los Alamos Neutron Science Center using the Detector for Advanced Neutron-Capture Experiments array along with a compact parallel-plate avalanche counter for fission-fragment detection. A new neutron-capture cross section was determined, and the absolute scale was set according to a concurrent measurement of the well-known 242mAm(n,f) cross section. The (n,γ) cross section was measured from thermal energy to an incident energy of 1 eV at which point the data quality was limited by the reaction yield in the laboratory. Our new 242mAm fission cross section was normalized to ENDF/B-VII.1 tomore » set the absolute scale, and it agreed well with the (n,f) cross section from thermal energy to 1 keV. Lastly, the average absolute capture-to-fission ratio was determined from thermal energy to En = 0.1 eV, and it was found to be 26(4)% as opposed to the ratio of 19% from the ENDF/B-VII.1 evaluation.« less

  5. Measurement of neutron-induced reactions on 242mAm

    NASA Astrophysics Data System (ADS)

    Buckner, M. Q.; Wu, C.-Y.; Henderson, R. A.; Bucher, B.; Chyzh, A.; Bredeweg, T. A.; Baramsai, B.; Couture, A.; Jandel, M.; Mosby, S.; Ullmann, J. L.; Dance Collaboration

    2016-09-01

    Neutron-induced reaction cross sections of 242mAm were measured at the Los Alamos Neutron Science Center using the Detector for Advanced Neutron-Capture Experiments array along with a compact parallel-plate avalanche counter for fission-fragment detection. A new neutron-capture cross section was determined relative to a simultaneous measurement of the well-known 242mAm(n,f) cross section. The (n, γ) cross section was measured from thermal to an incident energy of 1 eV. Our new 242mAm fission cross section was normalized to ENDF/B-VII.1 and agreed well with the (n,f) cross section reported in the literature from thermal energy to 1 keV. The capture-to-fission ratio was determined from thermal energy to En = 0.1 eV, and it was found to be (n, γ)/(n,f) = 26(4)% compared to 19% from ENDF/B-VII.1. Our latest results will be reported. US Department of Energy by Lawrence Livermore National Security, LLC Contract DE-AC52-07NA27344 and Los Alamos National Security, LLC Contract DE-AC52-06NA25396 and U.S. DOE/NNSA Office of Defense Nuclear Nonproliferation Research and Development.

  6. Production of cosmogenic isotopes 7Be, 10Be, 14C, 22Na, and 36Cl in the atmosphere: Altitudinal profiles of yield functions

    NASA Astrophysics Data System (ADS)

    Poluianov, S. V.; Kovaltsov, G. A.; Mishev, A. L.; Usoskin, I. G.

    2016-07-01

    New consistent and precise computations of the production of five cosmogenic radioisotopes, 7Be, 10Be, 14C, 22Na, and 36Cl, 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.

  7. AMS measurement of 10Be concentrations in marine sediments from Chile Trench at the TANDAR laboratory

    NASA Astrophysics Data System (ADS)

    Rodrigues, D.; Arazi, A.; Fernández Niello, J. O.; Martí, G. V.; Negri, A. E.; Abriola, D.; Capurro, O. A.; Cardona, M. A.; de Barbará, E.; Gollan, F.; Hojman, D.; Pacheco, A. J.; Samsolo, N.; Togneri, M.; Villanueva, D.

    2017-03-01

    The 10Be/9Be ratios in marine sediments samples from the Southern Chile Trench have been measured using accelerator mass spectrometry (AMS). The samples were measured at the TANDAR accelerator, where the discrimination of the 10Be radionuclides was achieved by means of a passive absorber in front of an ionization chamber. This setup along with the high voltage available, provided a complete suppression of the 10B isobar interference. The obtained values for the 10Be concentrations, of the order of 109 atoms/g, are the first 10Be measurements from the Southern Chile Trench and offer an excellent tracer to quantitatively study the recycling of sediments in Andean magmas.

  8. Inter-comparison of cosmogenic in-situ 3He, 21Ne and 36Cl at low latitude along an altitude transect on the SE slope of the Kilimanjaro volcano (3°S, Tanzania)

    NASA Astrophysics Data System (ADS)

    Schimmelpfennig, I.; Williams, A.; Pik, R.; Burnard, P.; Niedermann, S.; Finkel, R. C.; Benedetti, L.; Schneider, B.

    2010-12-01

    the data-set should enable progress to be made in the determination of the production rates of all three nuclides as soon as the production rate of one of the nuclides has been accurately defined. To our knowledge this is the first time that 36Cl has been measured in pyroxene. The method was validated by measuring 36Cl in co-existing plagioclase phenocrysts in one of the samples. [1] Gayer et al. (2004), EPSL 229, 91-104, [2] Amidon et al. (2008), EPSL 265, 287-301

  9. 50 CFR 622.496 - Annual catch limits (ACLs), annual catch targets (ACTs), and accountability measures (AMs).

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 50 Wildlife and Fisheries 12 2013-10-01 2013-10-01 false Annual catch limits (ACLs), annual catch.... Virgin Islands § 622.496 Annual catch limits (ACLs), annual catch targets (ACTs), and accountability measures (AMs). See § 622.12 for applicable ACLs and AMs....

  10. 50 CFR 622.457 - Annual catch limits (ACLs), annual catch targets (ACTs), and accountability measures (AMs).

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 50 Wildlife and Fisheries 12 2013-10-01 2013-10-01 false Annual catch limits (ACLs), annual catch.... Virgin Islands § 622.457 Annual catch limits (ACLs), annual catch targets (ACTs), and accountability measures (AMs). See § 622.12 for applicable ACLs and AMs....

  11. 50 CFR 622.439 - Annual catch limits (ACLs), annual catch targets (ACTs), and accountability measures (AMs).

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 50 Wildlife and Fisheries 12 2014-10-01 2014-10-01 false Annual catch limits (ACLs), annual catch.... Virgin Islands § 622.439 Annual catch limits (ACLs), annual catch targets (ACTs), and accountability measures (AMs). See § 622.12 for applicable ACLs and AMs....

  12. 50 CFR 622.439 - Annual catch limits (ACLs), annual catch targets (ACTs), and accountability measures (AMs).

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 50 Wildlife and Fisheries 12 2013-10-01 2013-10-01 false Annual catch limits (ACLs), annual catch.... Virgin Islands § 622.439 Annual catch limits (ACLs), annual catch targets (ACTs), and accountability measures (AMs). See § 622.12 for applicable ACLs and AMs....

  13. 50 CFR 622.457 - Annual catch limits (ACLs), annual catch targets (ACTs), and accountability measures (AMs).

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 50 Wildlife and Fisheries 12 2014-10-01 2014-10-01 false Annual catch limits (ACLs), annual catch.... Virgin Islands § 622.457 Annual catch limits (ACLs), annual catch targets (ACTs), and accountability measures (AMs). See § 622.12 for applicable ACLs and AMs....

  14. 50 CFR 622.496 - Annual catch limits (ACLs), annual catch targets (ACTs), and accountability measures (AMs).

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 50 Wildlife and Fisheries 12 2014-10-01 2014-10-01 false Annual catch limits (ACLs), annual catch.... Virgin Islands § 622.496 Annual catch limits (ACLs), annual catch targets (ACTs), and accountability measures (AMs). See § 622.12 for applicable ACLs and AMs....

  15. US Transuranium Registry report on the SU Am content of a whole body. Part III: Gamma-ray measurements

    SciTech Connect

    Palmer, H.E.; Spitz, H.B.; Rieksts, G.A.

    1985-10-01

    The SU Am measurements on the donor's body, followed by an analysis of each bone of the skeleton, have provided the best available calibration factors for measuring the SU Am content in the skeletons of the living. These calibration factors have already been useful in measuring the skeletal burden of several workers in the nuclear industry. This study has shown that differential linear scanning provides good results on the content of various parts of the skeleton. Previously used methods of head or leg counting for estimating total skeletal content of SU Am were also found to provide good results. These studies confirm previous recommendations that in-vivo measurement of the skull probably provides the best estimate of SU Am in the skeleton; however, other positions such as the knee are also found to be bilaterally symmetrical for identical bones on the right and left sides of the body. A comparison of measurements on the donor's body with those of other people with skeletal burdens of SU Am shows that differences in skeletal distribution do exist and are probably due to the age of the person, the duration of the skeletal SU Am burden, and perhaps the physical activity of the person. Additional measurements and studies are planned on the remaining half of the skeleton and they should further improve the accuracy of in-vivo measurements of SU Am in the human skeleton.

  16. Characterization of a diffusion-dominant system using chloride and chlorine isotopes (36Cl, 37Cl) for the confining layer of the Great Artesian Basin, Australia

    NASA Astrophysics Data System (ADS)

    Hasegawa, Takuma; Nakata, Kotaro; Mahara, Yasunori; Habermehl, M. A.; Oyama, Takahiro; Higashihara, Tomohiro

    2016-11-01

    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 (36Cl, 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, 36Cl/Cl ratio, and δ37Cl value in the confining layer decreased with depth at both Marree and Richmond. The 36Cl/Cl ratios at the shallower part of the confining layer are significantly higher than the in situ secular equilibrium (36Cl/Clse) calculated from the chemical compositions of the rock. The 36Cl/Cl ratio logarithmically decreased with depth. The calculated 36Cl/Clse is equivalent to the lowest 36Cl/Cl ratio at Richmond. In contrast, the 36Cl/Cl ratios at Marree are higher than the calculated 36Cl/Clse. The 36Cl/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 36Cl (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

  17. Energy measurement of cosmic-ray ions with the TRD of the AMS-02 experiment

    NASA Astrophysics Data System (ADS)

    Obermeier, Andreas

    Since May 2011 the AMS-02 experiment is installed on the ISS and is observing cosmic radiation. It consists of several state-of-the-art sub-detectors, which redundantly measure charge and energy of traversing particles. Due to the long exposure time of AMS-02 of many years the measurement of cosmic-ray energy spectra is mainly limited not by statistics, but by detector response. The measurement of momentum for protons and ions, for example, is limited by the spatial resolution and magnetic field strength of the silicon tracker. The maximum detectable rigidity (MDR, rigidity is momentum per charge) for protons is about 2 TV, for Helium below 4 TV (E<2.1 TeV/amu). In this contribution we investigate the possibility to extend the range of the energy measurement for heavy nuclei (Z>1) with the transition radiation detector (TRD). The main purpose of the TRD of AMS-02 is the discrimination between light particles (electrons and positrons) and heavy particles (like protons), and was thus designed as a threshold detector. The response function of the TRD, however, shows a steep increase in signal from the level of ionisation at a Lorentz factor gamma of about 500 to gamma≈ 5000, where the transition radiation signal saturates. The increase of the signal over this energy range may be used to measure the Lorentz factor for very high energy cosmic-ray nuclei, e.g. for helium nuclei between about 500 GeV/amu and 5 TeV/amu, well beyond the limits of the silicon tracker. From the response curve and the signal fluctuations in the TRD we derive the energy resolution of the TRD and compare it to the resolution of the silicon tracker. The TRD may outperform the tracker at high energies for ions heavier than protons. Another important application of this work is an independent determination of the MDR of the silicon tracker, which confirms earlier results.

  18. Towards 1‰ AMS 14C measurement precision at the Rafter Radiocarbon Laboratory

    NASA Astrophysics Data System (ADS)

    Turnbull, J. C.; Baisden, T. T.; Zondervan, A.; Kaiser, J.; Brailsford, G.; Moss, R.

    2012-12-01

    The radiocarbon content of atmospheric CO2 (Δ14CO2) is an increasingly important tracer used to quantify the different sources of CO2 in the atmosphere. Due to the absence of 14C in fossil fuels, 14CO2 is perhaps the best way to quantify recently added fossil fuel CO2 in the atmosphere. The sea-air CO2 flux also has Δ14C different from the atmosphere, so Δ14CO2 observations can be used to examine the one-way gross CO2 flux out of the oceans. Each one part per million (ppm) of fossil fuel CO2 added to the atmosphere decreases Δ14CO2 by about 2.6‰, and fossil fuel CO2 enhancements are typically in the range of a few ppm. The detection capability is therefore strongly influenced by the precision of 14C measurements. The World Meteorological Organization recommends a goal of 1‰ 14C precision, and Δ14CO2 measurements can currently be made to slightly better than 2‰ at several facilities. New Zealand has a long history of atmospheric Δ14CO2 measurements, starting in Wellington in 1955. Rafter lab recently obtained a new accelerator mass spectrometer (AMS) and developed a new graphitization system. A major focus emerging from the upgrade is the opportunity to expand the high precision atmospheric Δ14CO2 capability. Results from the first year of measurements indicate 1.3‰ repeatability on modern atmospheric CO2 in samples as small as one liter of whole air, a significant improvement over previously reported AMS 14C repeatability. We use new measurements from the long-term Baring Head Δ14CO2 record demonstrate the utility of this new high precision capability in interpreting atmospheric signals. We will report on development of graphitization procedures and AMS methodology which allow us to achieve this precision. Progress towards 1‰ precision will be discussed.

  19. Tissue residues, metabolism, and excretion of radiolabeled sodium chlorate (Na[36Cl]O3) in rats.

    PubMed

    Hakk, Heldur; Smith, David J; Shappell, Nancy W

    2007-03-07

    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 [36Cl]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.

  20. Geology and radiometric 14C-, 36Cl- and Th-/U-dating of the Fernpass rockslide (Tyrol, Austria)

    NASA Astrophysics Data System (ADS)

    Prager, C.; Ivy-Ochs, S.; Ostermann, M.; Synal, H.-A.; Patzelt, G.

    2009-01-01

    One of the largest mass movements in the Alps, the fossil Fernpass rockslide in the Northern Calcareous Alps (Tyrol, Austria), was dated absolutely for the first time. Three independent radiometric dating methods were applied to geologically individual sample sites and enabled a cross-checking of the results. Close to the scarp-front, rockslide-dammed torrent deposits indicate a 14C minimum age of at least 3380-3080 cal. yrs BP. The chronostratigraphic base of this backwater sequence has not been dated yet, but is assumed to date somewhat older into the middle Holocene. However, this coincides with two cosmogenic radionuclide 36Cl ages of sliding planes at the steep and rugged scarp. Exposure data thus obtained are 3400 ± 900 and 4800 ± 1200 yrs respectively with an arithmetic mean of 4100 ± 1300 yrs. Additional age data were acquired from post-depositional calcareous cements, which locally lithified the rockslide debris. These meteoric cements contain remarkably high Uranium total contents and yielded a 230Th/ 234U minimum age of about 4150 ± 100 yrs for the accumulation of the rockslide deposits. All dating data agree well and indicate that the Fernpass rockslide is of Subboreal age. Thus the intensively structured present morphology, characterised by the well-known cone-shaped Toma-hills and several lakes in the depressions, is indicative of primary rockslide morphology and clearly not shaped by late-glacial ice as assumed formerly.

  1. Implications of improved measurements of the highest energy SEPs by AMS and PAMELA

    NASA Astrophysics Data System (ADS)

    Whitman, K.; Bindi, V.; Consolandi, C.; Corti, C.; Yamashiro, B.

    2017-08-01

    Solar energetic particles (SEP) are a key target of heliophysics research, not only as exemplars of particle acceleration and transport processes that are ubiquitous in astrophysical plasmas, but also as the most intense transient radiation hazard for human and robotic space explorers. SEPs are very well-observed by spacecraft covering particle energies below several hundred MeV/nucleon. Multiple missions, stretching back over decades, have yielded a fairly complete description of SEP intensity, energy spectra, and composition up to a few hundred MeV/nucleon. SEP characteristics at higher energies are, by comparison, only poorly understood due to the relative dearth of high-energy measurements. This lack of high energy measurements has contributed to a disagreement within the heliophysics community regarding the source regions and mechanisms that accelerate particles up to GeV energies. In solar cycle 24, the Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA) and the Alpha Magnetic Spectrometer (AMS) have been taking measurements of the highest energy SEPs from ∼ 100 MeV to the GeV. Since the literature has discussed SEP acceleration to GeV energies in terms of Ground Level Enhancements (GLE), we will review the findings for GLEs in solar cycle 23. We will discuss the models and theories that address acceleration up to the GeV and how AMS and PAMELA measurements have the potential to advance the current understanding of SEP acceleration physics. Lastly, only 1-2 GLEs have occurred during solar cycle 24, so we will explore a set of SEP events that were observed in the ⩾100 MeV GOES channels, most of which were also observed by PAMELA and AMS.

  2. Towards the measurement of the13C(d, p)14C cross section using AMS

    NASA Astrophysics Data System (ADS)

    Murillo-Morales, S.; Barrón-Palos, L.; Chávez, E.; Araujo-Escalona, V.

    2017-07-01

    A plan to study the total cross section for the13C(d, p)14C nuclear reaction has been developed for energies in the center-of-mass frame between 133 and 400 keV. The proposed experiment will use a deuterium beam (1-3 MeV of energy) from the Instituto de Física-UNAM 5.5 MV Van de Graaff accelerator and the produced14C will be afterwards measured by AMS technique in the LEMA-UNAM (HVEE 1 MV Tandetron). One of the main goals is to study the performance of the LEMA-UNAM facility in the cross section measurement in comparison with other data reported in the literature, measured by other techniques. In this work we present the current status of these studies. The relevance of the13C(d, p)14C reaction in the study of compound nucleus formation as well as in some astrophysics scenarios, and the importance of the development of the AMS technique to measure cross sections of nuclear reactions of astrophysical interest in Mixico are also discussed.

  3. Neutron dosimetry for Hiroshima A-bomb survivors using AMS (accelerator mass spectrometry)

    SciTech Connect

    Straume, T.; Finkel, R.C.; Eddy, D. ); Kubik, P.W.; Gove, H.E.; Sharma, P. . Nuclear Structure Research Lab.); Fujita, S. ); Hoshi, M. )

    1990-05-01

    A substantial discrepancy exists between the measured values for thermal neutron activation and the values calculated using the new A-bomb dosimetry system, DS86. As part of a joint US-Japan effort aimed at resolving this discrepancy, we have shown that {sup 36}Cl/Cl in mineral samples (i.e., concrete, granite, tiles) can be measured with sufficient precision using accelerator mass spectrometry (AMS) to quantify the very low thermal neutron activation levels at distances up to {approximately}2000 m from the hypocenter in Hiroshima. Our initial measurement results show that activation of Cl by the bomb neutrons disagree with calculations based on the new DS86 dosimetry system, in the same direction as previous findings for Co and Eu. This is a preliminary report of work in progress. The principal objectives of this work are to reconstruct the thermal neutron fluence as a function of distance from the hypocenters in both Hiroshima and Nagasaki using {sup 36}Cl/Cl and obtain information about fast neutron fluence. 11 refs., 1 fig., 3 tabs.

  4. 50 CFR 622.411 - Annual catch limits (ACLs), annual catch targets (ACTs), and accountability measures (AMs).

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... OF THE CARIBBEAN, GULF OF MEXICO, AND SOUTH ATLANTIC Spiny Lobster Fishery of the Gulf of Mexico and... measures (AMs). For recreational and commercial spiny lobster landings combined, the ACL is 7.32 million...

  5. 50 CFR 622.411 - Annual catch limits (ACLs), annual catch targets (ACTs), and accountability measures (AMs).

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... OF THE CARIBBEAN, GULF OF MEXICO, AND SOUTH ATLANTIC Spiny Lobster Fishery of the Gulf of Mexico and... measures (AMs). For recreational and commercial spiny lobster landings combined, the ACL is 7.32 million...

  6. Zr/Nb isobar separation experiment for future 93Zr AMS measurement

    NASA Astrophysics Data System (ADS)

    Lu, W.; Anderson, T.; Bowers, M.; Bauder, W.; Collon, P.; Kutschera, W.; Kashiv, Y.; Lachner, J.; Martschini, M.; Ostdiek, K.; Robertson, D.; Schmitt, C.; Skulski, M.; Steier, P.

    2015-10-01

    93Zr (t1/2 = 1.6 Ma) is mostly produced by the main s-process in low-to-intermediate mass AGB stars. Large uncertainty exists in the current 92Zr(n,γ)93Zr Maxwellian Average cross section. This could have significant impact on nucleosynthesis calculations. Large amounts of 93Zr are also produced in nuclear reactors and pose long-term environmental radioactivity. Hence, measurement of 93Zr by the AMS is important for both fields above. We report here on progress in the development of AMS method to measure 93Zr. Compared with 98 MeV beam energy, Zr/Nb isobar position separation was improved using 155.2 MeV beam energy and Gas-Filled Magnet. Energy loss measurement with increased beam energy inside the detector indicates that higher beam energy can improve isobar energy loss separation. A chemical procedure to reduce the Nb content in Zr samples has been developed and tested. It reduces the 93Nb content by a factor of 1000.

  7. The U.S. Department of Energy's Aerial Measuring System (AMS)

    SciTech Connect

    Craig Marianno

    2008-03-01

    For nearly 40 years, aerial radiological search and survey missions have been performed by the United States Department of Energy's (USDOE) Remote Sensing Laboratory (RSL). Originally created in 1967 as Aerial Measurement Operations (AMO), the AMS mission has expanded to include acquiring baseline measurements, performing periodic area monitoring, and responding to radiological emergencies. In an accident scenario, AMS fixed-wing and/or rotary-wing systems can be deployed to map radiological deposition. A fixed-wing system is on standby twenty-fours per day, seven days per week and can be deployed within four hours of notification. It can quickly evaluate high levels of radiation which may constitute immediate health risks. To accomplish its mission the fixed-wing aircraft utilizes the Spectral Aerial Radiological Computer System (SPARCS) which records gross count and spectral information. Data from SPARCS is telemetered to ground stations and secure websites where it can be viewed and evaluated in near-real time. The rotary-wing system deploys following the critical phase of an accident and supports the DOE's Consequence Management Response Team (CMRT) in determining long term consequences of the accident. The rotary wing aircraft utilizes the Radiation and Environmental Data Acquisition and Recording System (REDAR). A 25-liter sodium iodide (NaI) spectral system and precise positioning allow distributed man-made activity of less than 1 {micro}R/hr at ground level to be precisely mapped. This talk will discuss history of the USDOE's AMS program and its current efforts to conduct baseline aerial surveys of some US cities.

  8. Fully automated measurement of field-dependent AMS using MFK1-FA Kappabridge equipped with 3D rotator

    NASA Astrophysics Data System (ADS)

    Chadima, Martin; Studynka, Jan

    2013-04-01

    Low-field magnetic susceptibility of paramagnetic and diamagnetic minerals is field-independent by definition being also field-independent in pure magnetite. On the other hand, in pyrrhotite, hematite and high-Ti titanomagnetite it may be clearly field-dependent. Consequently, the field-dependent AMS enables the magnetic fabric of the latter group of minerals to be separated from the whole-rock AMS. The methods for the determination of the field-dependent AMS consist of separate measurements of each specimen in several fields within the Rayleigh Law range and subsequent processing in which the field-independent and field-dependent AMS components are calculated. The disadvantage of this technique is that each specimen must be measured several times, which is relatively laborious and time consuming. Recently, a new 3D rotator was developed for the MFK1-FA Kappabridge, which rotates the specimen simultaneously about two axes with different velocities. The measurement is fully automated in such a way that, once the specimen is inserted into the rotator, it requires no additional manipulation to measure the full AMS tensor. Consequently, the 3D rotator enables to measure the AMS tensors in the pre-set field intensities without any operator interference. Whole procedure is controlled by newly developed Safyr5 software; once the measurements are finished, the acquired data are immediately processed and can be visualized in a standard way.

  9. Multiple dating approach (14C, U/Th and 36Cl) of tsunami-transported reef-top megaclasts on Bonaire (Leeward Antilles) - potential and current limitations

    NASA Astrophysics Data System (ADS)

    Rixhon, Gilles; May, Simon Matthias; Engel, Max; Mechernich, Silke; Keulertz, Rebecca; Schroeder-Ritzrau, Andrea; Fohlmeister, Jens; Frank, Norbert; Dunai, Tibor; Brueckner, Helmut

    2016-04-01

    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 36Cl 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

  10. Seismic slip history of the Aterno-Sulmona fault system in central Apennines (Italy) using in situ produced 36Cl cosmic ray exposure dating.

    NASA Astrophysics Data System (ADS)

    Jim, T.; Benedetti, L. C.; Bruno, P.; Visini, F.; Aumaitre, G.; Bourles, D. L.

    2014-12-01

    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. 36Cl 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.

  11. AMS measurements of 14C and 129I in seawater around radioactive waste dump sites

    NASA Astrophysics Data System (ADS)

    Povinec, P. P.; Oregioni, B.; Jull, A. J. T.; Kieser, W. E.; Zhao, X.-L.

    2000-10-01

    According to a recent IAEA compilation of inventories of radioactive wastes dumped in the world ocean, a total of 85 PBq of radioactive wastes were dumped, in the Atlantic (45 PBq), the Pacific (1.4 PBq) and the Arctic (38 PBq) Oceans and their marginal seas between 1946 and 1993, mostly in the form of low-level wastes. 3H, and 14C formed an important part of the beta-activity of these dumped wastes. Because of its long half-life, 14C will be the main constituent in possible leakages from the wastes in the future. On the other hand, 14C and 129I are important radioactive tracers which have been artificially introduced into the oceans. Small amounts of 14C and 129I can be easily measured by accelerator mass spectrometry (AMS) on mg-size samples of carbon and iodine extracted from 500 ml seawater samples. The high analytical sensitivity enables one therefore to find even trace amounts of 14C and 129I which could be released from radioactive wastes, and to compare the measured levels with the global distribution of these radionuclides. The IAEAs Marine Environment Laboratory (IAEA-MEL) has been engaged in an assessment program related to radioactive waste dumping in the oceans since 1992 and has participated in several expeditions to the Atlantic, Arctic, Indian and Pacific Oceans to sample seawater, biota and sediment for radiological assessment studies. In the present paper, we report on methods of 14C and 129I measurements in seawater by AMS and present data on the NE Atlantic, the Arctic and the NW Pacific Ocean dumping sites. A small increase of 14C was observed at the NE Atlantic dumping site.

  12. Methods for high precision 14C AMS measurement of atmospheric CO2 at LLNL

    SciTech Connect

    Graven, H D; Guilderson, T P; Keeling, R F

    2006-10-18

    Development of {sup 14}C analysis with precision better than 2{per_thousand} has the potential to expand the utility of {sup 14}CO{sub 2} measurements for carbon cycle investigations as atmospheric gradients currently approach traditional measurement precision of 2-5{per_thousand}. The AMS facility at the Center for Accelerator Mass Spectrometry, Lawrence Livermore National Laboratory, produces high and stable beam currents that enable efficient acquisition times for large numbers of {sup 14}C counts. One million {sup 14}C atoms can be detected in approximately 25 minutes, suggesting that near 1{per_thousand} counting precision is economically feasible at LLNL. The overall uncertainty in measured values is ultimately determined by the variation between measured ratios in several sputtering periods of the same sample and by the reproducibility of replicate samples. Experiments on the collection of one million counts on replicate samples of CO{sub 2} extracted from a whole air cylinder show a standard deviation of 1.7{per_thousand} in 36 samples measured over several wheels. This precision may be limited by the reproducibility of Oxalic Acid I standard samples, which is considerably poorer. We outline the procedures for high-precision sample handling and analysis that have enabled reproducibility in the cylinder extraction samples at the <2{per_thousand} level and describe future directions to continue increasing measurement precision at LLNL.

  13. The rock avalanche of the Mt. Peron (Eastern Alps, Italy): new insights from 36Cl exposure dating

    NASA Astrophysics Data System (ADS)

    Martin, Silvana; Ivy-ochs, Susan; Alfimov, Vasili; Vockenhuber, %Christof; Surian, Nicola; Campedel, Paolo; Rigo, Manuel; Viganò, Alfio; De Zorzi, Manuel

    2016-04-01

    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 36Cl 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

  14. Development of AM 1.5 global measurement procedures and international cell measurement round robin

    NASA Technical Reports Server (NTRS)

    Mueller, R.

    1985-01-01

    The development of the capability for measurement under global irradiance spectral distribution is reported. The airmass 1.5 global measurement procedure is given. Also given is the procedure and justification for using the large area pulsed solar simulator (LAPSS). The status of the international round robin of reference cell measurements managed by the Commission of European Communities (CEC) is described.

  15. Capture Cross-section Measurement of 241Am(n,γ) at J-PARC/MLF/ANNRI

    NASA Astrophysics Data System (ADS)

    Harada, H.; Ohta, M.; Kimura, A.; Furutaka, K.; Hirose, K.; Hara, K. Y.; Kin, T.; Kitatani, F.; Koizumi, M.; Nakamura, S.; Oshima, M.; Toh, Y.; Igashira, M.; Katabuchi, T.; Mizumoto, M.; Kino, K.; Kiyanagi, Y.; Fujii, T.; Fukutani, S.; Hori, J.; Takamiya, K.

    2014-05-01

    The 241Am(n, γ) 242Am cross sections have been measured for neutron energies between 0.01 and 10 eV using the Accurate Neutron-Nucleus Reaction measurement Instrument (ANNRI) installed at the Materials and Life-science experimental Facility (MLF) in J-PARC. ANNRI combines the strongest neutron-pulsed beam and a high energy resolution γ-ray spectrometer, making possible accurate measurements of neutron capture cross sections for highly radioactive samples. From the measured cross section, the Westcott neutron capture factor and strength of the first three resonances in 241Am are deduced. These results with precision less than 0.5 % are compared with those derived from JENDL-4.0.

  16. Late Pleistocene ages for the most recent volcanism and glacial-pluvial deposits at Big Pine volcanic field, California, USA, from cosmogenic 36Cl dating

    USGS Publications Warehouse

    Vazquez, Jorge A.; Woolford, Jeff M

    2015-01-01

    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 36Cl 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 36Cl 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 36Cl 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.

  17. The use of groundwater tracers, including {sup 36}Cl, {delta}{sup 18}O, and {delta}{sup 2}JH, in the study fo the Magothy aquifer, Maryland

    SciTech Connect

    Bond, C.A.; Mignerey, A.C.; Helz, G.R.

    1995-12-01

    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 36}Cl, {delta}{sup 18}O, and {delta}{sup 2}H. Also, three samples that contained anomalously high {sup 36}Cl/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 36}Cl and Cl{sup -} values to sea level rise and fall will be discussed.

  18. Distribution, Identification, and Quantification of Residues after Treatment of Ready-To-Eat Salami with (36)Cl-Labeled or Nonlabeled Chlorine Dioxide Gas.

    PubMed

    Smith, David J; Giddings, J Michael; Herges, Grant R; Ernst, William

    2016-11-09

    When ready-to-eat salami was treated in a closed system with (36)Cl-labeled ClO2 (5.5 mg/100 g of salami), essentially all radioactivity was deposited onto the salami. Administered (36)ClO2 was converted to (36)Cl-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.

  19. A Novel Electrochemical Sensor Based on [Ru(NH3)6]Cl3 as a Redox Indicator for the Detection of G-G Mismatched DNA.

    PubMed

    Zhu, Xiaoqian; Huang, Min; Li, Jiao; He, Hanping; Zhang, Xiuhua; Wang, Shengfu

    2017-01-01

    In this paper, a novel electrochemical sensor was developed for the rapid detection of G-G mismatched DNA based on hexaammineruthenium(III) chloride ([Ru(NH3)6]Cl3) as a redox indicator. The sensor platform was constructed by immobilizing small molecules (NC-linker) on the gold electrode via amide bonds. The as-prepared NC-linker as the nucleic acids recognition molecule can interact with the G base of DNA. After the sensor was incubated with G-G mismatched DNA, the double-stranded DNA (dsDNA) acted as carriers of the signal tags-[Ru(NH3)6]Cl3, which resulted in a remarkable electrochemical signal. More binding of [Ru(NH3)6]Cl3 led to increases of the electrochemical signal. Other mismatched DNA produced only a low response, as well as complementary DNA. Thus G-G mismatched DNA can be easily discriminated from other mismatched and complementary DNA based on the sensor. Furthermore, the method was simple, rapid and repeatable for the detection of G-G mismatched DNA. The selective detection of target dsDNA was achieved by a relative current ratio of the target and control DNA. These results demonstrated that this strategy could provide great promise for the rapid and specific detection of other sequence-specific DNA.

  20. Aerial Measuring System (AMS)/Israel Atomic Energy Commission (IAEC) Joint Comparison Study Report

    SciTech Connect

    Wasiolek, P.; Halevy, I.

    2013-12-23

    Under the 13th Bilateral Meeting to Combat Nuclear Terrorism conducted on January 8–9, 2013, the committee approved the development of a cost-effective proposal to conduct a Comparison Study of the Aerial Measuring System (AMS) of the U.S. Department of Energy (DOE), National Nuclear Security Administration (NNSA) and Israel Atomic Energy Commission (IAEC). The study was to be held at the Remote Sensing Laboratory (RSL), Nellis Air Force Base, Las Vegas, Nevada, with measurements at the Nevada National Security Site (NNSS). The goal of the AMS and the IAEC joint survey was to compare the responses of the two agencies’ aerial radiation detection systems to varied radioactive surface contamination levels and isotopic composition experienced at the NNSS, and the differing data processing techniques utilized by the respective teams. Considering that for the comparison both teams were using custom designed and built systems, the main focus of the short campaign was to investigate the impact of the detector size and data analysis techniques used by both teams. The AMS system, SPectral Advanced Radiological Computer System, Model A (SPARCS-A), designed and built by RSL, incorporates four different size sodium iodide (NaI) crystals: 1" × 1", 2" × 4" × 4", 2" × 4" ×16", and an “up-looking” 2" × 4" × 4". The Israel AMS System, Air RAM 2000, was designed by the IAEC Nuclear Research Center – Negev (NRCN) and built commercially by ROTEM Industries (Israel) and incorporates two 2" diameter × 2" long NaI crystals. The operational comparison was conducted at RSL-Nellis in Las Vegas, Nevada, during week of June 24–27, 2013. The Israeli system, Air RAM 2000, was shipped to RSL-Nellis and mounted together with the DOE SPARCS on a DOE Bell-412 helicopter for a series of aerial comparison measurements at local test ranges, including the Desert Rock Airport and Area 3 at the NNSS. A 4-person Israeli team from the IAEC NRCN supported the activity together with 11

  1. Measurements of L-Auger spectra of Pu, Am, Cf, and Fm and comparison with theory

    SciTech Connect

    Haynes, S.K.; Freedman, M.S.; Porter, F.T.

    1984-07-01

    The L-Auger spectra of 2 /sub 94//sup 39/Pu (64 lines), /sub 100//sup 254/Fm (54 lines), 2 /sub 95//sup 41/Am (41 LMM lines only), and 2 /sub 98//sup 50/Cf (35 LMM lines only) were scanned over the range 6--19 keV at high resolution (10/sup -3/< or =..delta..E/E< or =2 x 10/sup -3/) in the Argonne National Laboratory iron-free double toroidal spectrometer using thin (< or =1 ..mu..g/cm/sup 2/) isotopically separated radioactive sources. The observed energies of lines or line complexes agreed with Larkins's semiempirical predictions within the combined (theoretical plus experimental) standard deviations (1 s.d. = 10--20 eV in 10--20 keV) in 78% of the comparisons, and 19% were within 1--2 s.d. The measured intensities (relative to L/sub 3/M/sub 4/M/sub 5/) for Pu were compared to nonrelativistic predictions of McGuire for Z = 90, with the relativistic predictions of Chen et al. for Z = 94, and with a mixed system using Chen et al. for Coster-Kronig and McGuire for L-Auger transitions. Fm intensities (and Am and Cf qualitatively) could be compared only to relativistic theories. Relativistic predictions are clearly better for Pu, but are not, in general, satisfactory for either Pu or Fm; for all Pu and Fm lines, taken together, 58% are within 1 s.d., 30% in the range 1--2 s.d., and 12% greater than 2 s.d., with the relativistic predictions generally low except for the L/sub 3/MM band, which is in acceptable agreement.

  2. The Gas-Filled-Magnet at PRIME Lab: Increased Sensitivity of Cosmogenic Nuclide Measurements

    NASA Astrophysics Data System (ADS)

    Caffee, M. W.; Granger, D. E.; Woodruff, T. E.

    2015-12-01

    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, 26Al, 36Cl, and 129I. Be-10, 26Al, and 36Cl 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 26Al, 26Mg, precludes successful measurement of 26Al if AlO- is injected into the accelerator. Mg- doesn't form a stable negative ion so a 26Al measurement requires injection of 26Al-. 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 26Al/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 26Al, 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 26Al with a precision that is comparable to that obtained with 10Be. We are also using the GFM for routine measurements of 10Be and 36Cl. Although the improvement for these nuclides is not as pronounced as it is for 26Al, the GFM has improved the detection sensitivity for both. Our 10Be background is now ~ 5 x 10-16 and for 36Cl we can now run the source more

  3. 10Be and 36Cl Surface Exposure age of the Puerto Banderas Moraine, Lago Argentino, Argentina, 50°S

    NASA Astrophysics Data System (ADS)

    Becker, R. A.; Ackert, R. P.; Singer, B. S.; Douglass, D. C.; Caffee, M.; Kurz, M.; Mickelson, D. M.; Rabassa, J.

    2005-12-01

    The Antarctic Cold Reversal (ACR) and Younger Dryas (YD) are prominent late deglacial cool periods expressed in polar ice and high latitude marine sediments between 14.8-12.7 and 12.7-11.5 ka, respectively. Debate centers on the extent to which YD cooling affected the earth`s surface, particularly in the mid- to high latitudes of the Southern Hemisphere. Resolving the timing of late glacial cooling is critical to determining the degree of inter-hemispheric synchroneity as the climate system evolved after the global Last Glaciation Maximum (LGM) 16 ka. The Puerto Banderas moraine was deposited at 50°S in the rain shadow east of the Andes and between LGM moraines 60 km to the east and the present south Patagonian Ice Cap 40 km to the west. It is a sharp-crested ridge 30 km long and 10-15 m high, topped by numerous erratic boulders >1 m high ideally suited for surface exposure dating. Radiocarbon dating provides only broad age limits. A weighted mean of three 14C ages on peat younger than the moraine of 11.7±0.3 cal. ka (2 σ), along with glacier behavior elsewhere in the Andes, led John Mercer to propose that the Puerto Banderas moraine is late glacial, ca. 15 ka. Recent mapping and two additional 14C ages suggest that the moraine may have been deposited in stages between 15.4 and 11.9 ka. New cosmogenic surface exposure ages from the most prominent part of this moraine, however, indicate a considerably younger age. The weighted mean of 10Be ages from quartz in 8 boulders is 11.3±0.7 ka. Moreover, the weighted mean of 36Cl ages from 8 other boulders is 10.9±0.9 ka. The weighted mean age of all 16 boulders is 11.1±0.5 ka. Uncertainties include analytical and production rate contributions. Our previous work in the region suggests that production rates may be 10% higher than expected owing to reduced air pressure during the late glacial and the early Holocene. Thus, the age of 11.1±0.5 ka is a maximum for the Puerto Banderas moraine and although it is possible

  4. Measurement of the {sup 241}Am(n,2n) reaction cross section using the activation method

    SciTech Connect

    Perdikakis, G.; Papadopoulos, C.T.; Vlastou, R.; Kokkoris, M.; Galanopoulos, S.; Patronis, N.; Lagoyannis, A.; Spyrou, A.; Zarkadas, Ch.; Kalyva, G.; Kossionides, S.; Karamanis, D.

    2006-06-15

    In the context of the n{sub T}OF Collaboration, the measurement of the cross section of the reaction {sup 241}Am(n,2n){sup 240}Am, has been performed, for the first time at neutron energies from 8.8 to 11.4 MeV, by the activation method, relative to the {sup 27}Al(n,a){sup 24}Na reaction reference cross section. The monoenergetic neutron beam was produced at the 5.5 MV TANDEM accelerator of NCSR ''Demokritos,'' by means of the {sup 2}H(d,n){sup 3}He reaction, using a deuterium filled gas cell. The radioactive target consisted of a 37 GBq {sup 241}Am source enclosed in a Pb container. After the end of the irradiation, the activity induced by the neutron beam at the target and reference, was measured off-line by a 56% relative efficiency, HPGe detector.

  5. 50 CFR 622.388 - Annual catch limits (ACLs), annual catch targets (ACTs), and accountability measures (AMs).

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... accountability measures (AMs). (a) Gulf migratory group king mackerel—(1) Commercial sector. If commercial... king mackerel of zero, unless the best scientific information available determines that a bag limit... through June 1. (b) Atlantic migratory group king mackerel—(1) Commercial sector—(i) If...

  6. 50 CFR 622.388 - Annual catch limits (ACLs), annual catch targets (ACTs), and accountability measures (AMs).

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... accountability measures (AMs). (a) Gulf migratory group king mackerel—(1) Commercial sector. If commercial... king mackerel of zero, unless the best scientific information available determines that a bag limit... through June 1. (b) Atlantic migratory group king mackerel—(1) Commercial sector—(i) If...

  7. Measurement of 236U on the 1 MV AMS system at the Centro Nacional de Aceleradores (CNA)

    NASA Astrophysics Data System (ADS)

    Chamizo, E.; Christl, M.; Fifield, L. K.

    2015-09-01

    In this paper we present the first comprehensive analysis of the 1 MV AMS system at the Centro Nacional de Aceleradores (CNA, Seville, Spain) for 236U studies in environmental samples. In the last years, this radionuclide has become key in the AMS community, due to the very demanding 236U/238U abundance sensitivities required for general applications. As we demonstrate, the AMS system at the CNA is able to achieve sensitivity for the 236U/238U ratio of about 3 × 10-11 despite its compact design. The use of "239Pu"/238U ratio as a proxy for "236U"/235U background correction is proposed and tested with natural samples that were also studied on the 600 kV Tandy AMS system at the ETH Zürich. This correction is significant in the CNA case, due to the low mass resolving power of the low-energy spectrometer and to the lack of a third filter on the high-energy side. With the measurement of reference solutions supplied by the Institute for Reference Materials and Methods (IRMM-075), and reference natural matrixes provided by the International Atomic Energy Agency (IAEA-Soil-6, IAEA-375; 384; 386 and IAEA-RGU), we show that the 1 MV AMS system at the CNA can be routinely used for determinations of anthropogenic 236U at environmental levels.

  8. Separation of field-independent and field-dependent susceptibility tensors using a sequence of fully automated AMS measurements

    NASA Astrophysics Data System (ADS)

    Studynka, J.; Chadima, M.; Hrouda, F.; Suza, P.

    2013-12-01

    Low-field magnetic susceptibility of diamagnetic and paramagnetic minerals as well as that of pure magnetite and all single-domain ferromagnetic (s.l.) minerals is field-independent. In contrast, magnetic susceptibility of multi-domain pyrrhotite, hematite and titanomagnetite may significantly depend on the field intensity. Hence, the AMS data acquired in various fields have a great potential to separate the magnetic fabric carried by the latter group of minerals from the whole-rock fabric. The determination of the field variation of AMS consist of separate measurements of each sample in several fields within the Rayleigh Law range and subsequent processing in which the field-independent and field-dependent susceptibility tensors are calculated. The disadvantage of this technique is that each sample must be measured several times in various positions, which is relatively laborious and time consuming. Recently, a new 3D rotator was developed for the MFK1 Kappabridges which rotates the sample simultaneously about two axes with different velocities. The measurement is fully automated in such a way that, once the sample is mounted into the rotator, it requires no additional positioning to measure the full AMS tensor. The important advantage of the 3D rotator is that it enables to measure AMS in a sequence of pre-set field intensities without any operator manipulation. Whole procedure is computer-controlled and, once a sequence of measurements is finished, the acquired data are immediately processed and visualized. Examples of natural rocks demonstrating various types of field dependence of AMS are given.

  9. Production of the cosmogenic isotopes 3H, 7Be, 10Be, and 36Cl in the Earth's atmosphere by solar and galactic cosmic rays

    NASA Astrophysics Data System (ADS)

    Webber, W. R.; Higbie, P. R.; McCracken, K. G.

    2007-10-01

    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 36Cl 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 36Cl 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, 36Cl, 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.

  10. Ion irradiation of 37Cl implanted nuclear graphite: Effect of the energy deposition on the chlorine behavior and consequences for the mobility of 36Cl in irradiated graphite

    NASA Astrophysics Data System (ADS)

    Toulhoat, N.; Moncoffre, N.; Bérerd, N.; Pipon, Y.; Blondel, A.; Galy, N.; Sainsot, P.; Rouzaud, J.-N.; Deldicque, D.

    2015-09-01

    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 36Cl. 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 36Cl. 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 36Cl 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.

  11. Vibrations and reorientations of NH3 molecules in [Mn(NH3)6](ClO4)2 studied by infrared spectroscopy and theoretical (DFT) calculations.

    PubMed

    Hetmańczyk, Joanna; Hetmańczyk, Łukasz; Migdał-Mikuli, Anna; Mikuli, Edward

    2015-02-05

    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. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. Combining surface weathering analyses and cosmogenic 36Cl dating on the Pisia fault plane (Eastern Gulf of Corinth) to reveal the Holocene earthquake history

    NASA Astrophysics Data System (ADS)

    Mechernich, Silke; Schneiderwind, Sascha; Mason, Jack; Papanikolaou, Ioannis; Binnie, Steven A.; Dunai, Tibor J.; Reicherter, Klaus

    2017-04-01

    The deformation of the Corinth rift (Greece) is distributed along several E-W trending active normal faults like the 25-km-long Pisia fault, which experienced up to 110 cm of coseismic displacement during the 1981 Alkyonides earthquake sequence (Mw 6.7). Ages of paleoearthquakes and slip rate estimates of the Pisia fault are not known so far, despite the faults recent strong shaking and its significant destruction that reached until Athens. We mapped the continuous bedrock fault scarp of the central Pisia fault and revealed at least six different weathering stripes, which are interpreted as coseismic slip that stepwise exhumed the Pisia fault plane. The stripes were detected by color changes, lichen colonization, karst features (pitting and solution flute termination), and by the laser backscatter intensity. Their width and thus the amount of coseismic displacement ranges from 50-110 cm suggesting that six to seven paleoearthquakes of Mw 6.5-6.7 have exhumed the lower 5.15 m of the free-face. Forward modeling of 32 36Cl concentrations indicates that the Pisia fault moved at an average slip rate of 0.7 mm/yr during the Holocene. Modeled ages of individual earthquake events reveal recurrence intervals ranging between 0.2 and 3.1 kyr and a declined tectonic activity from this fault during the past 4.5 kyr. The exposure time in between most events was too narrow to be able to differentiate consecutive events based on cusps in the cosmogenic 36Cl concentrations as there is a rather low local 36Cl production rate (38°N, 625 m a.s.l.). Since such recurrence intervals and earthquake clustering phenomena appear to be quite common on active faults, mapping of independent offset features are often necessary to accurately restore the earthquake history on similarly located bedrock fault planes.

  13. Measurement and analysis of the Am243 neutron capture cross section at the n_TOF facility at CERN

    NASA Astrophysics Data System (ADS)

    Mendoza, E.; Cano-Ott, D.; Guerrero, C.; Berthoumieux, E.; Abbondanno, U.; Aerts, G.; Álvarez-Velarde, F.; Andriamonje, S.; Andrzejewski, J.; Assimakopoulos, P.; Audouin, L.; Badurek, G.; Balibrea, J.; Baumann, P.; Bečvář, F.; Belloni, F.; Calviño, F.; Calviani, M.; Capote, R.; Carrapiço, C.; Carrillo de Albornoz, A.; Cennini, P.; Chepel, V.; Chiaveri, E.; Colonna, N.; Cortes, G.; Couture, A.; Cox, J.; Dahlfors, M.; David, S.; Dillmann, I.; Dolfini, R.; Domingo-Pardo, C.; Dridi, W.; Duran, I.; Eleftheriadis, C.; Ferrant, L.; Ferrari, A.; Ferreira-Marques, R.; Fitzpatrick, L.; Frais-Koelbl, H.; Fujii, K.; Furman, W.; Goncalves, I.; González-Romero, E.; Goverdovski, A.; Gramegna, F.; Griesmayer, E.; Gunsing, F.; Haas, B.; Haight, R.; Heil, M.; Herrera-Martinez, A.; Igashira, M.; Isaev, S.; Jericha, E.; Käppeler, F.; Kadi, Y.; Karadimos, D.; Karamanis, D.; Ketlerov, V.; Kerveno, M.; Koehler, P.; Konovalov, V.; Kossionides, E.; Krtička, M.; Lampoudis, C.; Leeb, H.; Lindote, A.; Lo Meo, S.; Lopes, I.; Lossito, R.; Lozano, M.; Lukic, S.; Marganiec, J.; Marques, L.; Marrone, S.; Martínez, T.; Massimi, C.; Mastinu, P.; Mengoni, A.; Milazzo, P. M.; Moreau, C.; Mosconi, M.; Neves, F.; Oberhummer, H.; O'Brien, S.; Oshima, M.; Pancin, J.; Papachristodoulou, C.; Papadopoulos, C.; Paradela, C.; Patronis, N.; Pavlik, A.; Pavlopoulos, P.; Perrot, L.; Pigni, M. T.; Plag, R.; Plompen, A.; Plukis, A.; Poch, A.; Praena, J.; Pretel, C.; Quesada, J.; Rauscher, T.; Reifarth, R.; Rubbia, C.; Rudolf, G.; Rullhusen, P.; Salgado, J.; Santos, C.; Sarchiapone, L.; Savvidis, I.; Stephan, C.; Tagliente, G.; Tain, J. L.; Tassan-Got, L.; Tavora, L.; Terlizzi, R.; Vannini, G.; Vaz, P.; Ventura, A.; Villamarin, D.; Vicente, M. C.; Vlachoudis, V.; Vlastou, R.; Voss, F.; Walter, S.; Wendler, H.; Wiescher, M.; Wisshak, K.; n TOF Collaboration

    2014-09-01

    Background: The design of new nuclear reactors and transmutation devices requires to reduce the present neutron cross section uncertainties of minor actinides. Purpose: Improvement of the Am243(n,γ) cross section uncertainty. Method: The Am243(n,γ) cross section has been measured at the n_TOF facility at CERN with a BaF2 total absorption calorimeter, in the energy range between 0.7 eV and 2.5 keV. Results: The Am243(n ,γ) cross section has been successfully measured in the mentioned energy range. The resolved resonance region has been extended from 250 eV up to 400 eV. In the unresolved resonance region our results are compatible with one of the two incompatible capture data sets available below 2.5 keV. The data available in EXFOR and in the literature have been used to perform a simple analysis above 2.5 keV. Conclusions: The results of this measurement contribute to reduce the Am243(n,γ) cross section uncertainty and suggest that this cross section is underestimated up to 25% in the neutron energy range between 50 eV and a few keV in the present evaluated data libraries.

  14. 129I measurements on the 1MV AMS facility at the Centro Nacional de Aceleradores (CNA, Spain).

    PubMed

    Gómez-Guzmán, J M; López-Gutiérrez, J M; Pinto-Gómez, A R; Holm, E

    2012-01-01

    The AMS system at CNA has been the first 1MV compact AMS system designed and manufactured by HVE. In this paper we present the experimental set-up for (129)I measurements in this facility. Charge state +3 has been selected at high-energy side and an optimum stripper pressure of 6×10(-3)mbar of argon (mass thickness of about 0.15μgcm(-2)) has been reached to obtain lowest blank values ((129)I/(127)I≅3×10(-13)). The measurements of the reference materials provided by the IAEA have demonstrated the viability of this facility to make routine measurements of (129)I at environmental levels. This blank value obtained is enough for the measurement of most environmental samples and comparable with other reported backgrounds obtained in facilities working at higher energies and higher charge states.

  15. Tip convolution on HOPG surfaces measured in AM-AFM and interpreted using a combined experimental and simulation approach

    NASA Astrophysics Data System (ADS)

    Hu, Xiaoli; Chan, Nicholas; Martini, Ashlie; Egberts, Philip

    2017-01-01

    Amplitude modulated atomic force microscopy (AM-AFM) was used to examine the influence of the size of the AFM tip apex on the measured surface topography of single highly oriented pyrolytic graphite (HOPG) atomic steps. Experimental measurements were complemented by molecular dynamics simulations of AM-AFM and the results from both were evaluated by comparison of the measured or simulated width of the topography at the step to that predicted using simple rigid-body geometry. The results showed that the step width, which is a reflection of the resolution of the measurement, increased with tip size, as expected, but also that the difference between the measured/simulated step width and the geometric calculation was tip size dependent. The simulations suggested that this may be due to the deformation of the bodies and the effect of that deformation on the interaction force and oscillation amplitude. Overall, this study showed that the resolution of AM-AFM measurements of atomic steps can be correlated to tip size and that this relationship is affected by the deformation of the system.

  16. On the measurement of 10Be on the 1 MV compact AMS system at the Centro Nacional de Aceleradores (Spain)

    NASA Astrophysics Data System (ADS)

    Ruiz-Gómez, A.; Chamizo-Calvo, E.; López-Gutierrez, J. M.; García-León, M.; Müller, A. M.; Christl, M.

    2010-04-01

    In this work we present the most recent improvements performed by our group on 10Be measurements on the 1 MV AMS system recently set up at the CNA (Centro Nacional de Aceleradores), in Seville (Spain). Our efforts have been focused on the study of the viability of our system for BeO and BeF - measurements. To achieve this, different standard materials have been measured to demonstrate the reliability of the system for BeO measurements in a wide 10Be/ 9Be atomic ratio range and several environmental samples have been studied both at the 1 MV AMS CNA facility and at the 6 MV AMS ETH-PSI facility of Zurich to validate our measurements. The results show a good agreement between laboratories. New experiments also have been carried out selecting 1+ and 2+ charge states at the exit of the accelerator and inserting Si 3N 3.1 foils with different thicknesses to separate 10Be from its isobar, 10B. The influence of each foil on the overall transmission (detected 10Be compared to BeO - injected into the accelerator) and background level was also assessed. In addition some tests were also done to assess the viability of BeF 2 and BaBeF 4 measurements at our system. Several metal matrices and cathode preparation procedures for BeO samples were investigated to maximize current and cathode lifetime.

  17. A Cross-Cultural Validity of the E-Learning Acceptance Measure (ElAM) in Lebanon and England: A Confirmatory Factor Analysis

    ERIC Educational Resources Information Center

    Tarhini, Ali; Teo, Timothy; Tarhini, Takwa

    2016-01-01

    Despite the prevalence and significance of e-learning in education, there is a dearth of published instruments for educational researchers and practitioners that measure users' acceptance of e-learning. To meet this need, Teo (2010) developed the E-learning Acceptance Measure (ElAM). The main objective of this paper is to validate the ElAM (Teo,…

  18. A Cross-Cultural Validity of the E-Learning Acceptance Measure (ElAM) in Lebanon and England: A Confirmatory Factor Analysis

    ERIC Educational Resources Information Center

    Tarhini, Ali; Teo, Timothy; Tarhini, Takwa

    2016-01-01

    Despite the prevalence and significance of e-learning in education, there is a dearth of published instruments for educational researchers and practitioners that measure users' acceptance of e-learning. To meet this need, Teo (2010) developed the E-learning Acceptance Measure (ElAM). The main objective of this paper is to validate the ElAM (Teo,…

  19. Neutron-induced fission cross section measurement of 233U, 241Am and 243Am in the energy range 0.5 MeV ⩽ En ⩽ 20 MeV at n_TOF at CERN

    NASA Astrophysics Data System (ADS)

    Belloni, F.; Milazzo, P. M.; Calviani, M.; Colonna, N.; Mastinu, P.; Abbondanno, U.; Aerts, G.; Álvarez, H.; Álvarez-Velarde, F.; Andriamonje, S.; Andrzejewski, J.; Assimakopoulos, P.; Audouin, L.; Badurek, G.; Barbagallo, M.; Baumann, P.; Bečvář, F.; Berthoumieux, E.; Calviño, F.; Cerutti, F.; Cano-Ott, D.; Capote, R.; Carrapiço, C.; Carrillo de Albornoz, A.; Cennini, P.; Chepel, V.; Chiaveri, E.; Cortes, G.; Couture, A.; Cox, J.; Dahlfors, M.; David, S.; Dillmann, I.; Dolfini, R.; Domingo-Pardo, C.; Dridi, W.; Duran, I.; Eleftheriadis, C.; Embid-Segura, M.; Ferrant, L.; Ferrari, A.; Ferreira-Marques, R.; Fitzpatrick, L.; Frais-Koelbl, H.; Fujii, K.; Furman, W.; Goncalves, I.; González-Romero, E.; Goverdovski, A.; Gramegna, F.; Griesmayer, E.; Guerrero, C.; Gunsing, F.; Haas, B.; Haight, R.; Heil, M.; Herrera-Martinez, A.; Igashira, M.; Isaev, S.; Jericha, E.; Käppeler, F.; Kadi, Y.; Karadimos, D.; Karamanis, D.; Ketlerov, V.; Kerveno, M.; Koehler, P.; Konovalov, V.; Kossionides, E.; Krtička, M.; Lampoudis, C.; Lederer, C.; Leeb, H.; Lindote, A.; Lopes, I.; Lozano, M.; Lukic, S.; Marganiec, J.; Marques, L.; Marrone, S.; Martínez, T.; Massimi, C.; Meaze, M. H.; Mengoni, A.; Moreau, C.; Mosconi, M.; Neves, F.; Oberhummer, H.; O'Brien, S.; Oshima, M.; Pancin, J.; Papachristodoulou, C.; Papadopoulos, C.; Paradela, C.; Patronis, N.; Pavlik, A.; Pavlopoulos, P.; Perrot, L.; Pigni, M. T.; Plag, R.; Plompen, A.; Plukis, A.; Poch, A.; Praena, J.; Pretel, C.; Quesada, J.; Rauscher, T.; Reifarth, R.; Rosetti, M.; Rubbia, C.; Rudolf, G.; Rullhusen, P.; Salgado, J.; Santos, C.; Sarchiapone, L.; Savvidis, I.; Stephan, C.; Tagliente, G.; Tain, J. L.; Tassan-Got, L.; Tavora, L.; Terlizzi, R.; Vannini, G.; Vaz, P.; Ventura, A.; Villamarin, D.; Vincente, M. C.; Vlachoudis, V.; Vlastou, R.; Voss, F.; Wallner, A.; Walter, S.; Wendler, H.; Wiescher, M.; Wisshak, K.; n TOF Collaboration

    2012-10-01

    Neutron-induced fission cross section measurements of 233U, 243Am and 241Am relative to 235U have been carried out at the neutron time-of-flight facility n_TOF at CERN. A fast ionization chamber has been employed. All samples were located in the same detector; therefore the studied elements and the reference 235U target are subject to the same neutron beam.

  20. Collection and measurement of atmospheric contaminants during Skylab AM/MDA unmanned altitude chamber test

    NASA Technical Reports Server (NTRS)

    1972-01-01

    The analytical data obtained from both cryogenic and grab sampling of the atmosphere of the Skylab AM/MDA during an 84 hour unmanned chamber run are reported. The level of contaminants found at different points of the test chamber are tabulated. The results indicate that there was no clear trend of increasing or decreasing contaminant levels during the test run.

  1. Angle Measurement System (AMS) for Establishing Model Pitch and Roll Zero, and Performing Single Axis Angle Comparisons

    NASA Technical Reports Server (NTRS)

    Crawford, Bradley L.

    2007-01-01

    The angle measurement system (AMS) developed at NASA Langley Research Center (LaRC) is a system for many uses. It was originally developed to check taper fits in the wind tunnel model support system. The system was further developed to measure simultaneous pitch and roll angles using 3 orthogonally mounted accelerometers (3-axis). This 3-axis arrangement is used as a transfer standard from the calibration standard to the wind tunnel facility. It is generally used to establish model pitch and roll zero and performs the in-situ calibration on model attitude devices. The AMS originally used a laptop computer running DOS based software but has recently been upgraded to operate in a windows environment. Other improvements have also been made to the software to enhance its accuracy and add features. This paper will discuss the accuracy and calibration methodologies used in this system and some of the features that have contributed to its popularity.

  2. Deriving earthquake history of the Knidos Fault Zone, SW Turkey, using cosmogenic 36Cl surface exposure dating of the fault scarp.

    NASA Astrophysics Data System (ADS)

    Yildirim, Cengiz; Ersen Aksoy, Murat; Akif Sarikaya, Mehmet; Tuysuz, Okan; Genc, S. Can; Ertekin Doksanalti, Mustafa; Sahin, Sefa; Benedetti, Lucilla; Tesson, Jim; Aster Team

    2016-04-01

    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 36Cl 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 36Cl 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 36Cl 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

  3. Confronting recent AMS-02 positron fraction and Fermi-LAT extragalactic γ-ray background measurements with gravitino dark matter

    NASA Astrophysics Data System (ADS)

    Carquín, Edson; Díaz, Marco A.; Gómez-Vargas, Germán A.; Panes, Boris; Viaux, Nicolás

    2016-03-01

    Recent positron flux fraction measurements in cosmic-rays (CR) made by the AMS-02 detector confirm and extend the evidence on the existence of a new (yet unknown) source of high energy electrons and positrons. We test the gravitino dark matter of bilinear R-parity violating supersymmetric models as this electrons/positrons source. Being a long lived weak-interacting and spin 3/2 particle, it offers several particularities which makes it an attractive dark matter candidate. We compute the electron, positron and γ-ray fluxes produced by each gravitino decay channel as it would be detected at the Earth's position. Combining the flux from the different decay modes we are able to reproduce AMS-02 measurements of the positron fraction, as well as the electron and positron fluxes, with a gravitino dark matter mass in the range 1-3 TeV and lifetime of ˜1.0-0.7×1026 s. The high statistics measurement of electron and positron fluxes, and the flattening in the behaviour of the positron fraction recently found by AMS-02 allow us to determine that the preferred gravitino decaying mode by the fit is W±τ∓, unlike previous analyses. Then we study the viability of these scenarios through their implication in γ-ray observations. For this we use the Extragalactic γ-ray Background recently reported by the Fermi-LAT Collaboration and a state-of-the-art model of its known contributors. Based on the γ-ray analysis we exclude the gravitino parameter space which provides an acceptable explanation of the AMS-02 data. Therefore, we conclude that the gravitino of bilinear R-parity violating models is ruled out as the unique primary source of electrons and positrons needed to explain the rise in the positron fraction.

  4. Evaluation of (241)Am deposited in different parts of the leg bones and skeleton to justify in vivo measurements of the knee for estimating total skeletal activity.

    PubMed

    Khalaf, Majid; Brey, Richard R; Derryberry, DeWayne

    2013-01-01

    The percentage of Am deposited in different parts of leg bones relative to the total leg activity was calculated from radiochemical analysis results from six whole body donors participating in the U.S. Transuranium and Uranium Registries (USTUR). In five of these six USTUR cases, the percentage of Am deposited in the knee region as well as in the entire leg was separately calculated relative to total skeletal activity. The purpose of this study is to find a region in the leg that is both suitable for in vivo measurement of Am deposited in the bones and has a good correlation with the total skeletal Am burden. In all analyzed cases, the femur was the bone with the highest percentage of Am deposited in the leg (48.8%). In the five cases that have complete whole skeletal analysis, the percentage of Am activity in the knee relative to entire skeletal activity was 4.8%, and the average value of its coefficient of variation was 10.6%. The percentage of Am in the leg relative to total skeletal activity was 20% with an average coefficient of variation of 13.63%. The Am activity in the knee as well as in the leg was strongly correlated (R = 99.5% and R = 99.1%, respectively) with the amount of Am activity in the entire skeleton using a simple linear relationship. The highest correlation was found between the amount of Am deposited in the knee and the amount of Am deposited in the entire skeleton. This correlation is important because it might enable an accurate assessment of the total skeletal Am burden to be performed from in vivo monitoring of the knee region. In all analyzed cases, an excellent correlation (R = 99.9%) was found between the amount of Am activity in the knee and the amount of Am activity in the entire leg. The results of this study suggest three simple models: two models to predict the total skeletal activity based on either leg or knee activity, and the third model to predict the total leg activity based on knee activity. The results also suggest that the

  5. Measurement of 239Pu in urine samples at ultra-trace levels using a 1 MV compact AMS system

    NASA Astrophysics Data System (ADS)

    Hernández-Mendoza, H.; Chamizo, E.; Yllera, A.; García-León, M.; Delgado, A.

    2010-04-01

    Routine bioassay monitoring of Pu intake in exposed workers of research and nuclear industry is usually performed by alpha spectrometry. This technique involves large sample volumes of urine and time-consuming preparative and counting protocols. Compact accelerator mass spectrometry (AMS) facilities make feasible the determination of ultra low-level Pu activity concentrations and Pu isotopic ratios in biological samples (blood, urine and feces), being a rapid and cost-effective measurement technique. The plutonium results in urine samples presented here have been obtained on the 1 MV compact AMS system sited at the Centro Nacional de Aceleradores (CNA), in Seville, Spain. In this work, a different methodological approach has been developed alternative to the "classical" preparation of urine samples for alpha spectrometry. The procedure avoids the Pu precipitation step, and involves acid sample evaporation and acid digestion in a microwave oven. Finally, purification of plutonium was achieved by using chromatography columns filled up with BioRad AG1X2 anion exchange resin (Bio-Rad Laboratories Inc.). The total time needed for analysis is about 10 h, unlike the "classical" methods based on alpha spectrometry which need about 1 week. At present, it has been demonstrated that this method allows quantifying 239Pu activity concentrations in urine of, at least, 30 μBq (13 fg 239Pu). We can conclude that the procedure would be suitable to perform in vitro routine bioassay measurements. Moreover, the innovative application of AMS opens new and interesting analytical alternatives in this field.

  6. 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

  7. Sub-Antarctic glacier extensions in the Kerguelen region (49°S, Indian Ocean) over the past 24,000 years constrained by 36Cl moraine dating

    NASA Astrophysics Data System (ADS)

    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

    2017-04-01

    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 36Cl surface exposure ages from four sites in the Kerguelen Islands. The 36Cl 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.

  8. Transfer of 45Ca and 36Cl at the blood-nerve barrier of the sciatic nerve in rats fed low or high calcium diets

    SciTech Connect

    Wadhwani, K.C.; Murphy, V.A.; Rapoport, S.I. )

    1991-04-01

    Unidirectional fluxes of 45Ca, 36Cl, 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/36Cl 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.

  9. 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.

  10. 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.

  11. Simultaneous factor analysis of organic particle and gas mass spectra: AMS and PTR-MS measurements at an urban site

    NASA Astrophysics Data System (ADS)

    Slowik, J. G.; Vlasenko, A.; McGuire, M.; Evans, G. J.; Abbatt, J. P. D.

    2009-03-01

    During the winter component of the SPORT (Seasonal Particle Observations in the Region of Toronto) field campaign, particulate non-refractory chemical composition and concentration of selected volatile organic compounds (VOCs) were measured by an Aerodyne time-of-flight aerosol mass spectrometer (AMS) and a proton transfer reaction-mass spectrometer (PTR-MS), respectively. Sampling was performed in downtown Toronto ~15 m from a major road. The mass spectra from the AMS and PTR-MS were combined into a unified dataset, which was analyzed using positive matrix factorization (PMF). The two instruments were given equal weight in the PMF analysis by application of a scaling factor to the uncertainties of each instrument. A residual based metric, Δesc, was used to evaluate the relative weight. The PMF analysis yielded a 5-factor solution that included factors characteristic of regional transport, local traffic emissions, charbroiling, and oxidative processing. The unified dataset provides information on particle and VOC sources and atmospheric processing that cannot be obtained from the datasets of the individual instruments, such as apportionment of oxygenated VOCs to direct emission sources vs. secondary reaction products, improved correlation of oxygenated aerosol factors with photochemical age, and increased detail regarding the composition of oxygenated organic aerosol factors. This analysis represents the first application of PMF to a unified AMS/PTR-MS dataset.

  12. Simultaneous factor analysis of organic particle and gas mass spectra: AMS and PTR-MS measurements at an urban site

    NASA Astrophysics Data System (ADS)

    Slowik, J. G.; Vlasenko, A.; McGuire, M.; Evans, G. J.; Abbatt, J. P. D.

    2010-02-01

    During the winter component of the SPORT (Seasonal Particle Observations in the Region of Toronto) field campaign, particulate non-refractory chemical composition and concentration of selected volatile organic compounds (VOCs) were measured by an Aerodyne time-of-flight aerosol mass spectrometer (AMS) and a proton transfer reaction-mass spectrometer (PTR-MS), respectively. Sampling was performed in downtown Toronto ~15 m from a major road. The mass spectra from the AMS and PTR-MS were combined into a unified dataset, which was analysed using positive matrix factorization (PMF). The two instruments were given balanced weight in the PMF analysis by the application of a scaling factor to the uncertainties of each instrument. A residual based metric, Δesc, was used to evaluate the instrument relative weight within each solution. The PMF analysis yielded a 6-factor solution that included factors characteristic of regional transport, local traffic emissions, charbroiling and oxidative processing. The unified dataset provides information on emission sources (particle and VOC) and atmospheric processing that cannot be obtained from the datasets of the individual instruments: (1) apportionment of oxygenated VOCs to either direct emission sources or secondary reaction products; (2) improved correlation of oxygenated aerosol factors with photochemical age; and (3) increased detail regarding the composition of oxygenated organic aerosol factors. This analysis represents the first application of PMF to a unified AMS/PTR-MS dataset.

  13. A novel tertiary prep-HPLC method for the isolation of single amino acids for AMS-radiocarbon measurement.

    PubMed

    Fernandes, Ricardo; Koudelka, Tomas; Tholey, Andreas; Dreves, Alexander

    2017-07-15

    AMS-radiocarbon measurements of amino acids can potentially provide more reliable radiocarbon dates than bulk collagen analysis. Nonetheless, the applicability of such an approach is often limited by the low-throughput of existing isolation methods and difficulties in determining the contamination introduced during the separation process. A novel tertiary prep-HPLC amino acid isolation method was developed that relies on the combustion of eluted material without requiring any additional chemical steps. Amino acid separation was carried out using a gradient mix of pure water and phosphoric acid with an acetonitrile step in-between runs to remove hydrophobic molecules from the separation column. The amount of contaminant carbon and its (14)C content were determined from two-point measurements of collagen samples of known (14)C content. The amount of foreign carbon due to the isolation process was estimated at 4±1μg and its (14)C content was 0.43±0.01 F(14)C. Radiocarbon values corrected for carbon contamination have only a minor increase in uncertainties. For Holocene samples, this corresponds to an added uncertainty typically smaller than 10 (14)Cyears. The developed method can be added to routine AMS measurements without implying significant operational changes and offers a level of measurement uncertainty that is suitable for many archaeological, ecological, environmental, and biological applications. Copyright © 2017. Published by Elsevier B.V.

  14. Phase polymorphism of novel [Ru(NH3)6](ClO4)3—Comparison with [Ru(NH3)6](BF4)3. Part II

    NASA Astrophysics Data System (ADS)

    Dołęga, Diana; Mikuli, Edward; Górska, Natalia; Inaba, Akira; Hołderna-Natkaniec, Krystyna; Nitek, Wojciech

    2013-08-01

    [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.

  15. Imaging AMS

    SciTech Connect

    Freeman, S.P.H.T. |; Ramsey, C.B.; Hedges, R.E.M.

    1993-12-01

    The benefits of simultaneous high effective mass resolution and large spectrometer acceptance that accelerator mass spectrometry has afforded the bulk analysis of material samples by secondary ion mass spectrometry may also be applied to imaging SIMS. The authors are exploring imaging AMS with the addition to the Oxford {sup 14}C-AMS system of a scanning secondary ion source. It employs a sub micron probe and a separate Cs flood to further increase the useful ion yield. The source has been accommodated on the system by directly injecting sputtered ions into the accelerator without mass analysis. They are detected with a range of devices including new high-bandwidth detectors. Qualitative mass spectra may be easily generated by varying only the post-accelerator analysis magnet. Selected ion signals may be used for imaging. In developing the instrument for bioscience research the authors are establishing its capability for measuring the lighter elements prevalent in biological tissue. Importantly, the machine can map the distributions of radiocarbon labeled compounds with an efficiency of about 1{per_thousand}. A background due to misidentification of non-{sup 14}C ions as a result of the reduced ion mass filtering is too small to hinder high magnification microscopy.

  16. FISSION PARAMETERS MEASUREMENTS FOR NP, PU, AM, AND CM ISOTOPES INSIDE A SALT BLANKET MICROMODEL

    SciTech Connect

    Titarenko, Y. E.; Batyaev, V. F.; Karpikhin, E. I.; Zhivun, V. M.; Koldobsky, A. B.; Mulambetov, R. D.; Fischenko, D. V.; Kvasova, S. V.; Fomushkin, E. F.; Gavrilov, V. V.; Lopatkin, A. V.; Lopatkin, A. V.; Muratov, V. G.; Mashnik, S. G.; Yasuda, H.

    2001-01-01

    Pursuing verification of the nuclear data for actinides, we have made a run of experiments to determine reaction rates in facilities with different neutron spectra. The researches of the kind are particularly argent when going over from the transmutation physics studies to designing the transmutation reactors and developing their fuel cycle equipment. In this case, the nuclear data on the minor actinides (Np, Am, Cm) are notably interesting with the view to correct prediction of transmutation rates and t,o validation of hazardous nuclear and radiation environment for the external (off-reactor) fuel cycle. It is in the case of just those nuclides when the well-known ENDF/B6 and JENDL3.2 libraries give the most discrepant nuclear cross sections, thus necessitating the high- priority experimental tests.

  17. Chest wall thickness measurements: The alternative approach extended for {sup 241}Am

    SciTech Connect

    Kramer, G.H.; Burns, L.C.

    1997-02-01

    The Human Monitoring Laboratory has extended the technique of determining the chest wall thickness of an individual using information from the spectrum produced by internally deposited radionuclides. The technique has been investigated both theoretically and practically using germanium detectors and the Lawrence Livermore Torso Phantom. The phantom was used with a lung set containing homogeneously distributed {sup 241}Am. Chest wall thicknesses were varied by using a series of muscle equivalent overlay plates that gave a range of 1.6 cm to 3.9 cm thickness. It was found that a 3-cm chest wall thickness can be estimated to within 18%. Using a spectral addition technique 1 kBq was estimated to be the {open_quotes}practical{close_quotes} lower limit of activity for this method. 7 refs., 2 figs., 3 tabs.

  18. Exploring the cliff retreat response to base level change using SFM photogrammetry and cosmogenic 36Cl, Coal Cliffs, Utah, USA

    NASA Astrophysics Data System (ADS)

    Sheehan, C.; Ward, D.

    2015-12-01

    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

  19. Alpha and conversion electron spectroscopy of 238,239Pu and 241Am and alpha-conversion electron coincidence measurements

    SciTech Connect

    Dion, Michael P.; Miller, Brian W.; Warren, Glen A.

    2016-09-01

    A technique to determine the isotopics of a mixed actinide sample has been proposed by measuring the coincidence of the alpha particle during radioactive decay with the conversion electron (or Auger) emitted during the relaxation of the daughter isotope. This presents a unique signature to allow the deconvolution of isotopes that possess overlapping alpha particle energy. The work presented here are results of conversion electron spectroscopy of 241Am, 238Pu and 239Pu using a dual-stage peltier-cooled 25 mm2 silicon drift detector. A passivated ion implanted planar silicon detector provided measurements of alpha spectroscopy. The conversion electron spectra were evaluated from 20–55 keV based on fits to the dominant conversion electron emissions, which allowed the relative conversion electron emission intensities to be determined. These measurements provide crucial singles spectral information to aid in the coincident measurement approach.

  20. Measurement of the 241Am neutron capture cross section at the n_TOF facility at CERN

    NASA Astrophysics Data System (ADS)

    Mendoza, E.; Cano-Ott, D.; Altstadt, S.; Andriamonje, S.; Andrzejewski, J.; Audouin, L.; Balibrea, J.; Bécares, V.; Barbagallo, M.; Bečvář, F.; Belloni, F.; Berthier, B.; Berthoumieux, E.; Billowes, J.; Boccone, V.; Bosnar, D.; Brugger, M.; Calviño, F.; Calviani, M.; Carrapiço, C.; Cerutti, F.; Chiaveri, E.; Chin, M.; Colonna, N.; Cortés, G.; Cortés-Giraldo, M. A.; Diakaki, M.; Dillmann, I.; Domingo-Pardo, C.; Durán, I.; Dzysiuk, N.; Eleftheriadis, C.; Fernández-Ordóñez, M.; Ferrari, A.; Fraval, K.; Furman, V.; Gómez-Hornillos, M. B.; Ganesan, S.; García, A. R.; Giubrone, G.; Gonçalves, I. F.; González, E.; Goverdovski, A.; Gramegna, F.; Griesmayer, E.; Guerrero, C.; Gunsing, F.; Gurusamy, P.; Heftrich, T.; Heinitz, S.; Hernández-Prieto, A.; Heyse, J.; Jenkins, D. G.; Jericha, E.; Käppeler, F.; Kadi, Y.; Karadimos, D.; Katabuchi, T.; Ketlerov, V.; Khryachkov, V.; Koehler, P.; Kokkoris, M.; Kroll, J.; Krtička, M.; Lampoudis, C.; Langer, C.; Leal-Cidoncha, E.; Lederer, C.; Leeb, H.; Leong, L. S.; Lerendegui-Marco, J.; Licata, M.; Losito, R.; Manousos, A.; Marganiec, J.; Martínez, T.; Massimi, C.; Mastinu, P.; Mastromarco, M.; Mengoni, A.; Milazzo, P. M.; Mingrone, F.; Mirea, M.; Mondelaers, W.; Paradela, C.; Pavlik, A.; Perkowski, J.; Plompen, A. J. M.; Praena, J.; Quesada, J. M.; Rauscher, T.; Reifarth, R.; Riego-Perez, A.; Robles, M.; Roman, F.; Rubbia, C.; Ryan, J. A.; Sabaté-Gilarte, M.; Sarmento, R.; Saxena, A.; Schillebeeckx, P.; Schmidt, S.; Schumann, D.; Sedyshev, P.; Tagliente, G.; Tain, J. L.; Tarifeño-Saldivia, A.; Tarrío, D.; Tassan-Got, L.; Tsinganis, A.; Valenta, S.; Vannini, G.; Variale, V.; Vaz, P.; Ventura, A.; Vermeulen, M. J.; Versaci, R.; Vlachoudis, V.; Vlastou, R.; Wallner, A.; Ware, T.; Weigand, M.; Weiss, C.; Wright, T.; Žugec, P.

    2017-09-01

    New neutron cross section measurements of minor actinides have been performed recently in order to reduce the uncertainties in the evaluated data, which is important for the design of advanced nuclear reactors and, in particular, for determining their performance in the transmutation of nuclear waste. We have measured the 241Am(n,γ) cross section at the n_TOF facility between 0.2 eV and 10 keV with a BaF2 Total Absorption Calorimeter, and the analysis of the measurement has been recently concluded. Our results are in reasonable agreement below 20 eV with the ones published by C. Lampoudis et al. in 2013, who reported a 22% larger capture cross section up to 110 eV compared to experimental and evaluated data published before. Our results also indicate that the 241Am(n,γ) cross section is underestimated in the present evaluated libraries between 20 eV and 2 keV by 25%, on average, and up to 35% for certain evaluations and energy ranges.

  1. Alpha and conversion electron spectroscopy of 238,239Pu and 241Am and alpha-conversion electron coincidence measurements

    NASA Astrophysics Data System (ADS)

    Dion, Michael P.; Miller, Brian W.; Warren, Glen A.

    2016-09-01

    A technique to determine the isotopic constituents of a mixed actinide sample has been proposed by a coincident alpha-conversion electron measurement. This presents a unique signature to allow the unfolding of isotopes that possess overlapping alpha particle energy and reduce backgrounds of an unseparated sample. The work presented here are results of conversion electron spectroscopy of 241Am, 238Pu and 239Pu using a dual-stage peltier-cooled 25 mm2 silicon drift detector and alpha spectroscopy with a passivated ion implanted planar silicon detector. The conversion electron spectra were evaluated from 20-55 keV based on fits to the dominant conversion electron emissions, which allowed the relative conversion electron emission intensities to be determined. These measurements provide crucial singles spectral information and calibration to aid in the coincident measurement approach. Furthermore, an alpha-conversion electron spectrometer was assembled using the silicon based detectors described and results of a coincident spectrum analysis is reported for 241Am.

  2. Origin and history of waters associated with coalbed methane: 129I, 36Cl, and stable isotope results from the Fruitland Formation, CO and NM

    NASA Astrophysics Data System (ADS)

    Snyder, Glen T.; Riese, Walter C."Rusty"; Franks, Stephen; Fehn, Udo; Pelzmann, William L.; Gorody, Anthony W.; Moran, Jean E.

    2003-12-01

    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, 36Cl/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 36Cl/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

  3. Response function measurements of an NE102A organic scintillator using an 241Am-Be source

    NASA Astrophysics Data System (ADS)

    Naqvi, A. A.; Aksoy, A.; Khiari, F. Z.; Coban, A.; Nagadi, M. M.; Al-Ohali, M. A.; Al-Jalal, M. A.

    1994-07-01

    The response function of a 125 mm diameter NE102A organic scintillation detector has been measured over the 2.7-14.8 MeV neutron energy range. The detector response function was derived from the light output for monoenergetic neutrons and gamma rays. The light output of the detector for monoenergetic neutrons was measured by selecting narrowgates in the time-of-flight (TOF) spectrum for a 241Am-Be neutron source. In order to provide check points on the data, the detector light output was also measured for monoenergetic neutrons from the D(d, n) and T(d, n) reactions. The response function of the NE102A detector is in good agreement (within 1-5%) with the published data of Cecil et al. [Nucl. Instr. and Meth. 161 (1979) 439].

  4. Deriving aerosol hygroscopic mixing state from size-resolved CCN activity and HR-ToF-AMS measurements

    NASA Astrophysics Data System (ADS)

    Bhattu, Deepika; Tripathi, S. N.; Chakraborty, Abhishek

    2016-10-01

    The ability of a particle to uptake water and form a cloud droplet depends on its hygroscopicity. To understand its impact on cloud properties and ultimately radiative forcing, knowledge of chemically-resolved mixing state information or the one based on hygroscopic growth is crucial. Typically, global models assume either pure internal or external mixing state which might not be true for all conditions and sampling locations. To investigate into this, the current study employed an indirect approach to infer the probable mixing state. The hygroscopic parameters derived from κ-Kohler theory using size-resolved CCN measurements (κCCN) and bulk/size-resolved aerosol mass spectrometer (AMS) measurementsAMS) were compared. The accumulation mode particles were found to be more hygroscopic (κCCN = 0.24) than Aitken mode (κCCN = 0.13), perhaps due to increased ratio of inorganic to organic mass fraction. The activation diameter calculated from size-resolved CCN activity measurements at 5 different supersaturation (SS) levels varied in the range of 115 nm-42 nm with κCCN = 0.13-0.23 (avg = 0.18 ± 0.10 (±1σ)). Further, κAMS>κCCN was observed possibly due to the fact that organic and inorganic mass present in the Aitken mode was not correctly represented by bulk chemical composition and size-resolved fractional contribution of oxidized OA was not accurately accounted. Better correlation of organic fraction (forg) and κCCN at lower SS explained this behaviour. The decrease in κCCN with the time of the day was more pronounced at lower SS because of the relative mass reduction of soluble inorganic species by ∼17%. Despite the large differences between κ measured from two approaches, less over-prediction (up to 18%) between measured and predicted CCN concentration suggested lower impact of chemical composition and mixing state at higher SS. However, at lower SS, presences of externally mixed CCN-inactive aerosols lead to CCN over-prediction reflecting the

  5. AMS Data Analysis Overview

    SciTech Connect

    Malchow, Russell L.

    2015-04-20

    This presentation discusses standard techniques and processes used for radiation mapping (RM) via an AMS, Aerial Measurement System. The advantages and shortcomings of standard AMS-based RM are presented, along with some suggested areas for improvement. Issues touched on include what gets counted, data quality, background correction, data processing, altitude correction, isotope extraction, contouring, and time shift.

  6. Integration of AMS and ERDS Measurement Data into NARAC Dispersion Models FY05 Technology Integration Project Final Report

    SciTech Connect

    Foster, K; Arnold, E; Bonner, D; Eme, B; Fischer, K; Gash, J; Nasstrom, J; Walker, H; Guber, A; Logan, C; Wasiolek, P; Fulton, J

    2005-09-20

    Staff from Lawrence Livermore National Laboratory (LLNL), Bechtel Nevada Remote Sensing Laboratory (RSL), and Sandia National Laboratory (SNL) completed the proposed work for the Technology Integration Project titled Integration of AMS and ERDS Measurement Data into NARAC Dispersion Models. The objectives of this project were to develop software to convert Aerial Measurement Survey (AMS) and Emergency Response Data System (ERDS) field measurement data into a standard electronic format for transmission to the National Atmospheric Release Advisory Center (NARAC), and to streamline aspects of the NARAC operational atmospheric dispersion modeling system to quickly process these data for use in generating consequence calculations based on refined, field measurement-based estimates of the source strength. Although NARAC continues to develop and maintain a state-of-the-art atmospheric dispersion modeling system, model predictions are constrained by the availability of information to properly characterize the source term. During an actual atmospheric release, very little may be known initially about the source material properties, amount, or release time and location. Downwind measurements often provide the best information about the scope and nature of the release. The timely integration of field measurement data with model calculations is an obvious approach toward improving the model consequence predictions. By optimizing these predictions a more accurate representation of the consequences may be provided to (a) predict contamination levels which may be below the detectable limit of sensors, but which may still pose a significant hazard, (b) determine contamination is areas where measurements have not yet been made, and (c) prioritize the locations of future measurement surveys. By automating and streamlining much of the related field measurement data processing, these optimized predictions may be provided within a significantly reduced period, and with a reduction in

  7. The status of the AMS system at MALT in its 20th year

    NASA Astrophysics Data System (ADS)

    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

    2015-10-01

    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, 26Al, 36Cl, 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.

  8. 47 CFR 73.154 - AM directional antenna partial proof of performance measurements.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... from the latest complete proof of performance which are adjacent to the monitored radials. (b) The...) Measurement points shall be selected from the points measured in latest full proof of performance provided...

  9. 47 CFR 73.154 - AM directional antenna partial proof of performance measurements.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... from the latest complete proof of performance which are adjacent to the monitored radials. (b) The...) Measurement points shall be selected from the points measured in latest full proof of performance provided...

  10. Use of in vivo counting measurements to estimate internal doses from (241)Am in workers from the Mayak production association.

    PubMed

    Sokolova, Alexandra B; Suslova, Klara G; Efimov, Alexander V; Miller, Scott C

    2014-08-01

    Comparisons between results of in vivo counting measurements of americium burden and results from radiochemical analyses of organ samples taken at autopsy of 11 cases of former Mayak workers were made. The in vivo counting measurements were performed 3-8 y before death. The best agreement between in vivo counting measurements for americium and autopsy data was observed for the skull. For lungs and liver, the ratios of burden measured by in vivo counting to those obtained from radiochemical analyses data ranged from 0.7-3.8, while those for the skull were from 1.0-1.1. There was a good correlation between the estimates of americium burden in the entire skeleton obtained from in vivo counting with those obtained from autopsy data. Specifically, the skeletal burden ratio, in vivo counting/autopsy, averaged 0.9 ± 0.1. The prior human americium model, D-Am2010, used in vivo counting measurements for americium in the skeleton to estimate the contents of americium and plutonium at death. The results using this model indicate that in vivo counting measurements of the skull can be used to estimate internal doses from americium in the Mayak workers. Additionally, these measurements may also be used to provide a qualitative assessment of internal doses from plutonium.

  11. Measurements of M and L X-ray energies and relative intensities emanating from (241)Am source.

    PubMed

    Verma, H R

    2017-04-01

    Energies and relative Intensities of 13 X-ray transitions in the M X-ray spectrum (per 100 disintegrations of (241)Am) viz. M4N1, Mξ1,2, M3N1, Mα, Mβ, Mγ, M2N1, M3O4,5+M3P1, M3Q1, M1N3, M2N4+M1N3, M2O1 and M1O2,3 lines along with L1-L3 have been measured in addition to the 21L X-ray lines viz. Lℓ, Lt, Ls, Lα2, Lα1, Lη, Lβ6, Lβ2,15, Lβ4, Lβ5,7, Lβ1, Lβ3, Lβ9,10, Lγ5, Lγ1, Lγ2,8, Lγ3,6, Lγ4,4, Lγ13 including two new lines at 19.63 and 23.17keV, have been measured. Since the M and L X-ray lines of 93Np in the decay of (241)Am source are frequently used for energy and efficiency calibration of the Si(Li)/HpGe detectors, the present measurements have been undertaken with an objective to update the data since there are either no concrete data available (even in the Table of Radioactive Isotopes and Table of Radionuclides) or there exist inconsistencies/disparities in the data available in the earlier publications. We confirm the existence of L1-L3 X-ray transition (falling in the region of M X-ray energy range) and Lt, Ls and Lβ9,10 (forbidden transitions as per selection rules). However, the origin of the two new L X-ray lines at 19.63 and 23.17keV, both with intensities of 0.05±0.01%, could not be ascertained. Copyright © 2017. Published by Elsevier Ltd.

  12. High-sensitivity isobar-free AMS measurements and reference materials for 55Fe, 68Ge and 202gPb

    NASA Astrophysics Data System (ADS)

    Wallner, A.; Bichler, M.; Buczak, K.; Fink, D.; Forstner, O.; Golser, R.; Hotchkis, M. A. C.; Klix, A.; Krasa, A.; Kutschera, W.; Lederer, C.; Plompen, A.; Priller, A.; Schumann, D.; Semkova, V.; Steier, P.

    2013-01-01

    Isobaric interference represents one of the major limitations in mass spectrometry. For a few cases in AMS with tandem accelerators, isobaric interference is completely excluded like the well-known major isotopes 14C, 26Al, 129I. Additional isotopes are 55Fe (t1/2 = 2.74 years), 68Ge (t1/2 = 270.9 days) and 202Pb (t1/2 = 52.5 kyr), with 68Ge and 202Pb never been used in AMS so far. Their respective stable isobars, 55Mn, 68Zn and 202Hg do not form stable negative ions. The exceptional sensitivity of AMS for 55Fe, 68Ge and 202gPb offers important insights into such different fields like nuclear astrophysics, fundamental nuclear physics and technological applications. VERA, a dedicated AMS facility is well suited for developing procedures for new and non-standard isotopes. AMS measurements at the VERA facility established low backgrounds for these radionuclides in natural samples. Limits for isotope ratios of <10-15, <10-16 and ⩽2 × 10-14 were measured for 55Fe/56Fe, 68Ge/70Ge and 202Pb/Pb, respectively. In order to generate accurate isotope ratios of sample materials, AMS relies on the parallel measurement of reference materials with well-known ratios. A new and highly accurate reference material for 55Fe measurements with an uncertainty of ±1.6% was produced from a certified reference solution. In case of 68Ge dedicated neutron activations produced a sufficiently large number of 68Ge atoms that allowed quantifying them through the activity of its decay product 68Ga. Finally, for 202Pb, the short-lived isobar 202Tl was produced via neutron activation and served as a proxy for 202Pb AMS measurements.

  13. More than 35 large earthquakes broke the Fucino faults (Central Italy) in the last 15 ka, as revealed from in situ 36Cl exposure dating

    NASA Astrophysics Data System (ADS)

    Benedetti, L. C.; Schlagenhauf, A.; Manighetti, I.; Gaudemer, Y.; Finkel, R. C.; Malavieille, J.; Bourles, D. L.

    2012-12-01

    Using 36Cl exposure dating, we recover the Holocene earthquake history of 7 of the large seismogenic normal faults that form the broad-scale Fucino fault system in Central Italy. It is the first time that seismic history is quantified at such a broad scale encompassing many interacting faults. Some of the Fucino faults have recently broken in two devastating large earthquakes, Avezano in 1915 (M ≈ 7), and L'Aquila in 2009 (Mw 6.3). We focus here on 7 major faults of the Fucino system, that form two distinct NNW-trending networks, Fucino North (FN analyzed faults: Velino-Magnola, VM; Campo-Felice, CF; Fiamigniano, FI) and Fucino South (FS analyzed faults: San Sebastiano, SB; Parasano, PR; Trasacco, TR), separated by the oblique Tre-Monti fault (TM). Each network includes a major fault (VM in FN; SB in FS) associated to secondary faults (CF, FI, PR, TR). We collected 800 samples from the well-preserved limestone scarps of the 7 faults and modeled their 36Cl concentrations to derive their exhumation history and hence quantify the slips and ages of the large earthquakes that produced the exhumations. We found that more than 35 large earthquakes broke the Fucino faults over the last ≈ 15 ka. Most of these earthquakes occurred during three 2-3 kyr long phases of paroxysmal seismic activity that struck the entire Fucino system, one at 12-9 ka, another one at 6-4 ka, and a more recent one at 2.5-0.5 ka. These phases of paroxysmal activity were separated by periods of relative quiescence. During each of the two oldest phases, all faults broke in several large earthquakes that clustered over a short time. During the most recent phase, only the FN faults broke. The Fiamigniano fault is the one to have ruptured most recently in the cluster, about 0.5 ka ago. This last event might have been the 1349 AD historical earthquake that destroyed the nearby villages. The largest faults of both the FN and FS systems broke in much shorter clusters (≈ 1-1.5 kyr) than the secondary

  14. Pore water dating by 129I: What do 36Cl/Cl ratio, dissolved 4He concentration, δ37Cl and 129I/127I ratio suggest in the Mobara Gas field, Japan?

    NASA Astrophysics Data System (ADS)

    Mahara, Y.; Ohta, T.; Tokunaga, T.

    2010-12-01

    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 36Cl/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 36Cl/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

  15. Implications of 36Cl exposure ages from Skye, northwest Scotland for the timing of ice stream deglaciation and deglacial ice dynamics

    NASA Astrophysics Data System (ADS)

    Small, David; Rinterknecht, Vincent; Austin, William E. N.; Bates, Richard; Benn, Douglas I.; Scourse, James D.; Bourlès, Didier L.; Hibbert, Fiona D.

    2016-10-01

    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 36Cl 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.

  16. Are AMS 7Be measurements for a lithium solar neutrino detector practical?

    NASA Astrophysics Data System (ADS)

    Fireman, E. L.; Litherland, A. E.; Rowley, J. K.

    1987-11-01

    An efficient, low-background method of measuring 7Be is necessary to make a solar neutrino detector using lithium practical. Accelerator mass spectrometric 7Be measurements with BeO sputter sources are inefficient because of the small molecule (atom) to ion conversion. By collecting the sputtered BeO, that has not been accelerated, on an aluminum electrode and preparing additional sources from the collected Be, the overall efficiency might be raised sufficiently so that a lithium solar neutrino detector would be practical.

  17. DOE/NNSA Aerial Measuring System (AMS): Flying the 'Real' Thing

    SciTech Connect

    Craig Lyons

    2011-06-24

    This slide show documents aerial radiation surveys over Japan. Map product is a compilation of daily aerial measuring system missions from the Fukushima Daiichi power plant to 80 km radius. In addition, other flights were conducted over US military bases and the US embassy.

  18. Target preparation for milligram sized 14C samples and data evaluation for AMS measurements

    NASA Astrophysics Data System (ADS)

    Andree, Michael; Beer, Jürg; Oeschger, Hans; Bonani, G.; Hofmann, H. J.; Morenzoni, E.; Nessi, M.; Suter, M.; Wölfli, W.

    1984-11-01

    Our preparation technique produces in a glow-discharge an amorphous carbon deposit on a copper substrate. The process starts with 1.6 cm 3 CO 2 STP (900 μg carbon) which is reduced over hot zinc to CO and subsequently cracked in the discharge. The yield of the process is typically 80%. With these targets in the Zürich ion source ion currents up to 20 μA are obtained. The background of samples prepared with this technique is presently around 30 ka (2.5% MODERN). The precision after half an hour measuring time for a modern sample is 0.7% and 2.7% for a three half-lives old sample, including the errors of the background and the NBS oxalic acid measurement. The method we use to correct for the background of the preparation and the accelerator as well as for the fractionation in the accelerator is presented.

  19. Precision measurement of 0.5 GeV-3 TeV electrons and positrons using the AMS Electromagnetic Calorimeter

    NASA Astrophysics Data System (ADS)

    Kounine, A.; Weng, Z.; Xu, W.; Zhang, C.

    2017-10-01

    The Alpha Magnetic Spectrometer, AMS, is successfully collecting data on the International Space Station since its installation on May 19, 2011. One of the main objectives of AMS is the precision measurement of high energy cosmic ray electrons and positrons. The key detector for this measurement is the Electromagnetic Calorimeter. Reconstruction of electrons and positrons in the calorimeter uses a 3-dimensional shower parametrization, which accounts for the detector specifics: finite size of the calorimeter, non-uniform efficiency of the signal collection, and saturation effects due to the electronics and due to high energy density in the active calorimeter elements. This technique provides AMS with a precision energy measurement of electrons and positrons up to several TeV as well as an excellent rejection of the proton background.

  20. A batch preparation method for graphite targets with low background for AMS [sup 14]C measurements

    SciTech Connect

    Kitagawa, Hiroyuki International Research Center for Japanese Studies, Nishikyp-ku, Kyoto ); Masuzawa, Toshiyuki; Matsumoto, Eiji ); Makamura, Toshio )

    1993-01-01

    The authors have developed a method of graphitization from CO[sub 2] samples for accurate [sup 14]C measurements by accelerator mass spectrometry. Their batch method, using a sealed Vycor tube, reduces the risk of contamination during graphitization and makes it possible to prepare many samples in a short time (typically 20 samples per day). They also describe details of the target-preparation method involving carbon isotopic fractionation during graphitization, yield of graphite from CO[sub 2], ion-beam intensity of the target, and background (or blank) level estimated using bituminous coal.

  1. In situ isotopic studies of the U-depleted Allende CAI Curious Marie: Pre-accretionary alteration and the co-existence of 26Al and 36Cl in the early solar nebula

    NASA Astrophysics Data System (ADS)

    Tang, Haolan; Liu, Ming-Chang; McKeegan, Kevin D.; Tissot, Francois L. H.; Dauphas, Nicolas

    2017-06-01

    The isotopic composition of oxygen as well as 26Al-26Mg and 36Cl-36S systematics were studied in Curious Marie, an aqueously altered Allende CAI characterized by a Group II REE pattern and a large 235U excess produced by the decay of short-lived 247Cm. Oxygen isotopic compositions in the secondary minerals of Curious Marie follow a mass-dependent fractionation line with a relatively homogenous depletion in 16O (Δ17O of -8‰) compared to unaltered minerals of CAI components. Both Mg and S show large excesses of radiogenic isotopes (26Mg∗ and 36S∗) that are uniformly distributed within the CAI, independent of parent/daughter ratio. A model initial 26Al/27Al ratio [(6.2 ± 0.9) × 10-5], calculated using the bulk Al/Mg ratio and the uniform δ26Mg∗ ∼ +43‰, is similar to the canonical initial solar system value within error. The exceptionally high bulk Al/Mg ratio of this CAI (∼95) compared to other inclusions is presumably due to Mg mobilization by fluids. Therefore, the model initial 26Al/27Al ratio of this CAI implies not only the early condensation of the CAI precursor but also that aqueous alteration occurred early, when 26Al was still at or near the canonical value. This alteration event is most likely responsible for the U depletion in Curious Marie and occurred at most 50 kyr after CAI formation, leading to a revised estimate of the early solar system 247Cm/235U ratio of (5.6 ± 0.3) × 10-5. The Mg isotopic composition in Curious Marie was subsequently homogenized by closed-system thermal processing without contamination by chondritic Mg. The large, homogeneous 36S excesses (Δ36S∗ ∼ +97‰) detected in the secondary phases of Curious Marie are attributed to 36Cl decay (t1/2 = 0.3 Myr) that was introduced by Cl-rich fluids during the aqueous alteration event that led to sodalite formation. A model 36Cl/35Cl ratio of (2.3 ± 0.6) × 10-5 is calculated at the time of aqueous alteration, translating into an initial 36Cl/35Cl ratio of ∼1.7-3

  2. AMS-02 antiprotons reloaded

    SciTech Connect

    Kappl, Rolf; Reinert, Annika; Winkler, Martin Wolfgang E-mail: areinert@th.physik.uni-bonn.de

    2015-10-01

    The AMS-02 collaboration has released preliminary data on the antiproton fraction in cosmic rays. The surprisingly hard antiproton spectrum at high rigidity has triggered speculations about a possible primary antiproton component originating from dark matter annihilations. In this note, we employ newly available AMS-02 boron to carbon data to update the secondary antiproton flux within the standard two-zone diffusion model. The new background permits a considerably better fit to the measured antiproton fraction compared to previous estimates. This is mainly a consequence of the smaller slope of the diffusion coefficient favored by the new AMS-02 boron to carbon data.

  3. Review of the results of measurements of the fluxes of the charged components of galactic cosmic rays in the experiments PAMELA and AMS-02

    NASA Astrophysics Data System (ADS)

    Alekseev, V. V.; Belotsky, K. M.; Bogomolov, Yu. V.; Budaev, R. I.; Galper, A. M.; Dunaeva, O. A.; Kirillov, A. A.; Kuznetsov, A. V.; Lukyanov, A. D.; Mayorov, A. G.; Mayorova, M. A.; Malakhov, V. V.; Mosichkin, A. F.; Okrugin, A. A.; Rodenko, S. A.; Shitova, A. M.

    2017-09-01

    The paper provides a review of the results of precision measurements of the fluxes of different charged components of galactic cosmic rays (positrons and antiprotons, protons and helium nuclei) in modern experiments with magnetic spectrometers PAMELA and AMS-02, operating successfully for a few years (since 2006 and 2011, respectively) in Earth orbit. A priority of the PAMELA spectrometer scientific discoveries is noted. It is also noted that the measurements from the AMS-02 experiment are of high statistical accuracy and have reliably confirmed previous data, having been able to advance to a higher energy range.

  4. Simultaneous measurement of neutron-induced fission and capture cross sections for 241Am at neutron energies below fission threshold

    NASA Astrophysics Data System (ADS)

    Hirose, K.; Nishio, K.; Makii, H.; Nishinaka, I.; Ota, S.; Nagayama, T.; Tamura, N.; Goto, S.; Andreyev, A. N.; Vermeulen, M. J.; Gillespie, S.; Barton, C.; Kimura, A.; Harada, H.; Meigo, S.; Chiba, S.; Ohtsuki, T.

    2017-06-01

    Fission and capture reactions were simultaneously measured in the neutron-induced reactions of 241Am at the spallation neutron facility of the Japan Proton Accelerator Research Complex (J-PARC). Data for the neutron energy range of En=0.1-20 eV were taken with the TOF method. The fission events were observed by detecting prompt neutrons accompanied by fission using liquid organic scintillators. The capture reaction was measured by detecting γ rays emitted in the deexcitation of the compound nuclei using the same detectors, where the prompt fission neutrons and capture γ rays were separated by a pulse shape analysis. The cross sections were obtained by normalizing the relative yields at the first resonance to evaluations or other experimental data. The ratio of the fission to capture cross sections at each resonance is compared with those from an evaluated nuclear data library and other experimental data. Some differences were found between the present values and the library/literature values at several resonances.

  5. Spatial dependent diffusion of cosmic rays and the excess of primary electrons derived from high precision measurements by AMS-02

    NASA Astrophysics Data System (ADS)

    Jin, Chao; Guo, Yi-Qing; Hu, Hong-Bo

    2016-01-01

    The precise spectra of Cosmic Ray (CR) electrons and positrons have been published by the measurement of AMS-02. It is reasonable to regard the difference between the electron and positron spectra (ΔΦ = Φe- -Φe+) as being dominated by primary electrons. The resulting electron spectrum shows no sign of spectral softening above 20 GeV, which is in contrast with the prediction of the standard model of CR propagation. In this work, we generalize the analytic one-dimensional two-halo model of diffusion to a three-dimensional realistic calculation by implementing spatial variant diffusion coefficients in the DRAGON package. As a result, we can reproduce the spectral hardening of protons observed by several experiments, and predict an excess of high energy primary electrons which agrees with the measurement reasonably well. Unlike the break spectrum obtained for protons, the model calculation predicts a smooth electron excess and thus slightly over-predicts the flux from tens of GeV to 100 GeV. To understand this issue, further experimental and theoretical studies are necessary. Supported by Natural Sciences Foundation of China (11135010)

  6. Mid-Holocene cluster of large-scale landslides revealed in the Southwestern Alps by 36Cl dating. Insight on an Alpine-scale landslide activity

    NASA Astrophysics Data System (ADS)

    Zerathe, Swann; Lebourg, Thomas; Braucher, Régis; Bourlès, Didier

    2014-04-01

    Although it is generally assumed that the internal structure of a slope (e.g. lithology and rock mass properties, inherited faults and heterogeneities, etc.) is preponderant for the progressive development of large-scale landslides, the ability to identify triggering factors responsible for final slope failures such as glacial debuttressing, seismic activities or climatic changes, especially when considering landslide cluster at an orogen-scale, is still debated. Highlighting in this study the spatial and temporal concordant clustering of deep-seated slope failures in the external Southwestern Alps, we discuss and review the possible causes for such wide-spread slope instabilities at both local and larger (Alpine) scale. High resolution field mapping coupled with electrical resistivity tomography first allows establishing an inventory of large landslides in the Southwestern Alps, determining their structural model, precising their depth limit (100-200 m) as well as the involved rock volumes (>107 m3). We show that they developed in the same geostructural context of thick mudstone layers overlain by faulted limestone and followed a block-spread model of deformation that could evolve in rock-collapse events. Cosmic ray exposure dating (CRE), using both 36Cl and 10Be in coexisting limestone and chert, respectively, has been carried out from the main scarps of six Deep Seated Landslides (DSL) and leads to landslide-failure CRE ages ranging from 3.7 to 4.7 ka. They highlighted: (i) mainly single and fast ruptures and (ii) a possible concomitant initiation with a main peak of activity between 3.3 and 5.1 ka, centered at ca 4.2 ka. Because this region was not affected by historical glaciations events, landslide triggering by glacial unloading can be excluded. The presented data combined with field observations preferentially suggest that these failures were climatically driven and were most likely controlled by high pressure changes in the karstic medium. In effect, the

  7. Real-Time Secondary Aerosol Formation Measurements using a Photooxidation Reactor (PAM) and AMS in Urban Air and Biomass Smoke

    NASA Astrophysics Data System (ADS)

    Ortega, A. M.; Cubison, M.; Hayes, P. L.; Brune, W. H.; Hu, W.; Flynn, J. H.; Grossberg, N.; Lefer, B. L.; Alvarez, S. L.; Rappenglueck, B.; Bon, D.; Graus, M.; Warneke, C.; Gilman, J. B.; Kuster, W. C.; De Gouw, J. A.; Sullivan, A. P.; Jimenez, J. L.

    2011-12-01

    Recent field studies reveal large formation of secondary organic aerosol (SOA) under urban polluted ambient conditions, while SOA formation in biomass burning smoke appears to be variable but sometimes substantial. To study this formation in real-time, a Potential Aerosol Mass (PAM) photooxidation reactor was deployed with submicron aerosol size and chemical composition measurements during two studies: FLAME-3, a biomass-burning study at USDA Fire Sciences Laboratory in Missoula in 2009, MT and CalNex-LA in Pasadena, CA in 2010. A high-resolution aerosol mass spectrometer (HR-AMS) and a scanning mobility particle sizer (SMPS) alternated sampling unprocessed and PAM-processed aerosol. The PAM reactor produces OH concentrations up to 4 orders of magnitude higher than in ambient air, achieving equivalent aging of ~2 weeks in 5 minutes of processing. The OH intensity was also scanned every 20 min. in both field studies. Results show the value of PAM-AMS as a tool for in-situ evaluation of changes in OA concentration and composition due to SOA formation and POA oxidation. In FLAME-3, net SOA formation was variable among smokes from different biomasses; however, OA oxidation was always observed. The average SOA enhancement factor was 1.7 +/- 0.5 of the initial POA. Reactive VOCs such as toluene, monoterpenes, and acetaldehyde, as measured from a PIT-MS, decreased with increased PAM processing; however, formic acid, acetone, and some unidentified OVOCs increased after significant exposure to high oxidant levels suggesting multigenerational chemistry. Results from CalNex-LA show enhancement of SOA and inorganic aerosol from gas-phase precursors. This enhanced OA mass increase from PAM processing is maximum at night and correlates with trimethylbenzene concentrations, which indicates the dominance of short-lived SOA precursors in the LA Basin. A traditional SOA model with mostly aromatic precursors underpredicts the amount of SOA formed by about an order-of-magnitude, which

  8. Some Lessons Learned From the SIPACT Simulations on the Design of PWR and Improvement of AM Measures

    SciTech Connect

    Pochard, R.; Jedrzejewski, F.; Nilsuwankosit, S.

    2002-07-01

    In the general context of the nuclear activities, life extension of the existing plants is the interesting option for countries that are already well equipped with NPPs. As the working life of 60 years is now expected possible for some well maintained plants, their safety measures needs to be improved such that they should be comparable to the new or future designs, taken into account the results from the probabilistic and the deterministic accident analysis. To accomplish this aim, the Accident Management (AM) is the important part of the process that must be utilized including possible automation of some processes. At INSTN, the extensive sensitivity studies related to the feed and bleed process on the primary and the secondary side had been carried out with the SIPACT simulator, based on the Cathare code, for a 900 MWe pressurized water reactor. The simulations had been mainly conducted for the Beyond Design Basis Accident (BDBA) condition. This condition included the total loss of feed-water and a small break with the loss of the high pressure injection system (HPIS). From these studies, several interesting findings had been obtained. For AM purpose and with the bleeding process, the criterion called 'the safety time margin' for core uncover was introduced. By plotting the safety time margin against the bleeding time, the relation between them was established and used to optimize, when possible, the AM measures. For the scenario that involved the total loss of feed water, in case of full bleeding, a window was found for the bleeding time around the degradation of the heat exchange in SGs would be resulted. In this scenario, one of the solutions was to open only one relief valve at first in order to let through only the minimal mass. At the time of the injection by the accumulator, the other two relief valves were then opened. As a result, the flow through the relief valves could be effectively compensated by the flow from the accumulator, the mass balance in

  9. Age evaluation and causation of rock-slope failures along the western margin of the Antrim Lava Group (ALG), Northern Ireland, based on cosmogenic isotope (36Cl) surface exposure dating

    NASA Astrophysics Data System (ADS)

    Southall, David W.; Wilson, Peter; Dunlop, Paul; Schnabel, Christoph; Rodés, Ángel; Gulliver, Pauline; Xu, Sheng

    2017-05-01

    The temporal pattern of postglacial rock-slope failure in a glaciated upland area of Ireland (the western margin of the Antrim Lava Group) was evaluated using both 36Cl exposure dating of surface boulders on run-out debris and 14C dating of basal organic soils from depressions on the debris. The majority of the 36Cl ages ( 21-15 ka) indicate that major failures occurred during or immediately following local deglaciation ( 18-17 ka). Other ages ( 14-9 ka) suggest some later, smaller-scale failures during the Lateglacial and/or early Holocene. The 14C ages (2.36-0.15 cal ka BP) indicate the very late onset of organic accumulation and do not provide close limiting age constraints. Rock-slope failure during or immediately following local deglaciation was probably in response to some combination of glacial debuttressing, slope steepening and paraglacial stress release. Later failures may have been triggered by seismic activity associated with glacio-isostatic crustal uplift and/or permafrost degradation consequent upon climate change. The 36Cl ages support the findings of previous studies that show the deglacial - Lateglacial period in northwest Ireland and Scotland to have been one of enhanced rock-slope failure. Table S2 Concentrations of main elements (as oxides) etc.

  10. The internal structure of lava flows—insights from AMS measurements II: Hawaiian pahoehoe, toothpaste lava and 'a'ā

    NASA Astrophysics Data System (ADS)

    Cañón-Tapia, Edgardo; Walker, George P. L.; Herrero-Bervera, Emilio

    1997-03-01

    We studied the anisotropy of magnetic susceptibility (AMS) of 22 basaltic flow units, including S-type pahoehoe, P-type pahoehoe, toothpaste lava and 'a'ā emplaced over different slopes in two Hawaiian islands. Systematic differences occur in several aspects of AMS (mean susceptibility, degree of anisotropy, magnetic fabric and orientation of the principal susceptibilities) among the morphological types that can be related to different modes of lava emplacement. AMS also detects systematic changes in the rate of shear with position in a unit, allowing us to infer local flow direction and some other aspects of the velocity field of each unit. 'A'ā flows are subject to stronger deformation than pahoehoe, and also their internal parts behave more like a unit. According to AMS, the central part of pahoehoe commonly reveals a different deformation history than the upper and lower extremes, probably resulting from endogenous growth.

  11. Accelerator Mass Spectrometric (AMS) Measurements of Plutonium Activity Concentrations and 240Pu/239Pu Atom Ratios In Soil Extracts Supplied by the Carlsbad Environmental Monitoring & Research Center

    SciTech Connect

    Hamilton, T F; Brown, T A; Marchetti, A A; Martinelli, R E; Kehl, S R

    2005-02-28

    Plutonium-239 ({sup 239}Pu) and plutonium-239+240 ({sup 239+240}Pu) activities concentrations and {sup 240}Pu/{sup 239}Pu atom ratios are reported for a series of chemically purified soil extracts received from the Carlsbad Environmental Monitoring & Research Center (CEMRC) in New Mexico. Samples were analyzed without further purification at the Lawrence Livermore National Laboratory (LLNL) using accelerator mass spectrometry (AMS). This report also includes a brief description of the AMS system and internal laboratory procedures used to ensure the quality and reliability of the measurement data.

  12. Fission Cross-section Measurements of (233)U, (245)Cm and (241,243)Am at CERN n_TOF Facility

    SciTech Connect

    Calviani, M.; Koehler, Paul Edward; N_TOF collaboration,

    2011-01-01

    Neutron-induced fission cross-sections of minor actinides have been measured using the n-TOF white neutron source at CERN, Geneva, as part of a large experimental program aiming at collecting new data relevant for nuclear astrophysics and for the design of advanced reactor systems. The measurements at n-TOF take advantage of the innovative features of the n-TOF facility, namely the wide energy range, high instantaneous neutron flux and good energy resolution. Final results on the fission cross-section of {sup 233}U, {sup 245}Cm and {sup 243}Am from thermal to 20 MeV are here reported, together with preliminary results for {sup 241}Am. The measurement have been performed with a dedicated Fast Ionization Chamber (FIC), a fission fragment detector with a very high efficiency, relative to the very well known cross-section of {sup 235}U, measured simultaneously with the same detector.

  13. Cloud condensation nuclei (CCN) and HR-ToF-AMS measurements at a coastal site in Hong Kong: size-resolved CCN activity and closure analysis

    NASA Astrophysics Data System (ADS)

    Meng, J. W.; Yeung, M. C.; Li, Y. J.; Lee, B. Y. L.; Chan, C. K.

    2014-04-01

    The cloud condensation nuclei (CCN) properties of atmospheric aerosols were measured on 1-30 May 2011 at a coastal site in Hong Kong. Size-resolved CCN activation curves, the ratio of number concentration of CCN (NCCN) to aerosol concentration (NCN) as a function of particle size, were obtained at supersaturation (SS) = 0.15%, 0.35%, 0.50%, and 0.70% using a DMT CCN counter (CCNc) and a TSI scanning mobility particle sizer (SMPS). The mean bulk size-integrated NCCN ranged from ∼500 cm-3 at SS = 0.15% to ∼2100 cm-3 at SS = 0.70%, and the mean bulk NCCN / NCN ratio ranged from 0.16 at SS = 0.15% to 0.65 at SS = 0.70%. The average critical mobility diameters (D50) at SS = 0.15%, 0.35%, 0.50%, and 0.70% were 116 nm, 67 nm, 56 nm, and 46 nm, respectively. The corresponding average hygroscopic parameters (κCCN) were 0.39, 0.36, 0.31, and 0.28. The decrease in κCCN can be attributed to the increase in organic to inorganic volume ratio as particle size decreases, as measured by an Aerodyne high resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). The κCCN correlates reasonably well with κAMS based on size-resolved AMS measurements: κAMS = κorg × forg + κinorg × finorg, where forg and finorg are the organic and inorganic volume fractions, respectively, κorg = 0.1 and κinorg = 0.6, with a R2 of 0.51. In closure analysis, NCCN was estimated by integrating the measured size-resolved NCN for particles larger than D50 derived from κ assuming internal mixing state. Estimates using κAMS from size-resolved AMS measurements show that the measured and predicted NCCN were generally within 10% of each other at all four SS. The deviation increased to 26% when κAMS was calculated from bulk PM1 AMS measurements of particles because PM1 was dominated by particles of 200 nm to 500 nm in diameter, which had a larger inorganic fraction than those of D50 (particle diameter < 200 nm). A constant κ = 0.33 (the average value of size-resolved κAMS over the

  14. A quantitative PGNAA study for use in aqueous solution measurements using Am-Be neutron source and BGO scintillation detector

    NASA Astrophysics Data System (ADS)

    Ghal-Eh, N.; Ahmadi, P.; Doost-Mohammadi, V.

    2016-02-01

    A prompt gamma neutron activation analysis (PGNAA) system including an Am-Be neutron source and BGO scintillation detector are used for quantitative analysis of bulk samples. Both Monte Carlo-simulated and experimental data are considered as input data libraries for two different procedures based on neural network and least squares methods. The results confirm the feasibility and precision of the proposed methods.

  15. 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 [36Cl] radiotracer studies.

    PubMed

    Dambournet, Damien; Leclerc, Hervé; Vimont, Alexandre; Lavalley, Jean-Claude; Nickkho-Amiry, Mahmood; Daturi, Marco; Winfield, John M

    2009-03-07

    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 [(36)Cl]-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(36)Cl as a result of the room temperature dehydrochlorination of [(36)Cl]-labelled tert-butyl chloride provides additional evidence that HTB-AlF(2.6)(OH)(0.4) can behave as a Lewis acid.

  16. Importance of intraocular pressure measurement at 6:00 a.m. in bed and in darkness in suspected and glaucomatous patients.

    PubMed

    Cronemberger, Sebastião; Silva, Andréa Cristiane Lopes da; Calixto, Nassim

    2010-01-01

    To assess the importance of intraocular pressure measurement obtained at 6:00 a.m. in bed and darkness for the diagnosis and intraocular pressure control of primary open-angle glaucoma. Retrospective analysis of the daily curve of intraocular pressure of suspects and glaucomatous patients under treatment. Suspects were classified as intraocular pressure values ranging from 19 to 24 mmHg in isolated measurements and/or cup/disc ratio > 0.7 in one or both eyes and/or asymmetry of cup/disc ratio > 0.3 and a normal visual field. Each daily curve of intraocular pressure comprised five to seven IOP measurements with Goldmann applanation tonometer at 9:00 a.m., 12:00 p.m., 3:00 and/or 6:00 and 10:00 p.m. and/or 12:00 a.m. and in the following day morning at 6:00 a.m. in supine position in bed and in darkness with Perkins tonometer before the patient had stood up. Only the daily curves of intraocular pressure that presented an intraocular pressure peak (difference between the higher and the lesser intraocular pressure value) >6 mmHg were analyzed. In these daily curves, the average intraocular pressure and the standard deviation were calculated. The average intraocular pressure and standard deviation values were compared with the normal superior limits: average + two standard deviation of average intraocular pressure and standard deviation of intraocular pressure daily curve from normal patients of the same age group. Daily curves were considered abnormal when their average intraocular pressure and standard deviation values were above the normal superior limits. Secondary and congenital glaucoma were excluded. Daily curves of intraocular pressure of 565 eyes were analyzed; 361 suspected eyes and 204 eyes with primary open-angle glaucoma. In suspects, 64.3% presented an intraocular pressure peak at 6:00 a.m. in bed. In primary open-angle glaucoma, 68.6% presented an intraocular pressure peak at 6:00 a.m. in bed. In 5.3% of the suspects and in 5.9% of primary open

  17. The alpha and beta emitter measurement system in INER. Institute of Nuclear Energy Research.

    PubMed

    Wuu, Jyi-Lan; Yuan, Ming-Chen; Su, Shi-Hwa; Hwang, Wen-Son

    2002-01-01

    An alpha/beta emitter measurement system used to calibrate surface sources following the guidelines of ISO 8769 has been established in Institute of Nuclear Energy Research (INER) around the year 2000. This system consists of a windowless proportional counter with a uniformity of 0.28% when measuring the emission rate of a source on a centered area of 100 mm x 150 mm, and a uniformity of 0.62% when the source area was 150 mm x 200 mm. Four 100 mm x 150 mm sources (90Sr + 90Y, 36Cl, 14C and 241Am) had been measured by this system. The measurement results of the above four sources when compared with those of National Physical Laboratory, UK (NPL) showed difference between the two laboratories of < 1%.

  18. The modified FACS calcein AM retention assay: A high throughput flow cytometer based method to measure cytotoxicity.

    PubMed

    Gillissen, M A; Yasuda, E; de Jong, G; Levie, S E; Go, D; Spits, H; van Helden, P M; Hazenberg, M D

    2016-07-01

    Current methods to determine cellular cytotoxicity in vitro are hampered by background signals that are caused by auto-fluorescent target and effector cells and by non-specific cell death. We combined and adjusted existing cell viability assays to develop a method that allows for highly reproducible, accurate, single cell analysis by high throughput FACS, in which non-specific cell death is corrected for. In this assay the number of living, calcein AM labeled cells that are green fluorescent are quantified by adding a fixed number of unlabeled calibration beads to the analysis. Using this modified FACS calcein AM retention method, we found EC50 values to be highly reproducible and considerably lower compared to EC50 values obtained by conventional assays, displaying the high sensitivity of this assay. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

  19. Climate Change to the Nuclear Fuel Cycle: Expanding the spectral (14)CO(2) database for non-AMS Field Measurement Systems

    NASA Astrophysics Data System (ADS)

    Marino, B. D. V.; Odonnell, R. G.; Tolliver, D. E.

    2014-06-01

    Accelerator Mass Spectrometry (AMS) is well known and universally employed for radiocarbon analysis but is not adaptable to in-situ field measurements limiting applications. 14CO2 is a key tracer for fossil fuel CO2 as well as for release of enriched 14CO2 characteristic of the nuclear fuel cycle with ∆14CO2 values ranging from -1000 to ˜+500 per mil. However, to exploit the full value of in situ 14CO2 data in diverse climate change and nuclear fuel cycle applications, high data rate temporal and spatial field measurement sensors and systems are required. The development of non-AMS methods based on quantum cascade laser, cavity ring down and optogalvanic spectroscopy are emerging applications but not fully developed for field use or widely accepted. Spectral data for lasing transitions for 14CO2 are lacking in contrast to HITRAN data available for 12CO2 (626) and 13CO2 (636) (among other isotopologues 628, 638, etc.) in the spectral databases limiting development and innovation in non-AMS 14CO2 sensors and systems. We review the corpus of 14CO2 spectral data available in the literature and document grating tuned isotopic lasers (e.g., Freed 19901; Bradley et al., 19862), well suited for expanded spectral studies of 14CO2 and inclusion in the HITRAN database. Non-AMS 14CO2 approaches are reviewed with suggestions for future work to support field systems for 14CO2 measurements. Available isotopic lasers for 14CO2 collaborative studies are described.

  20. Testing the 14C ages and conservative behavior of dissolved 14C in a carbonate aquifer in Yucca Flat, Nevada (USA), using 36Cl from groundwater and packrat middens

    NASA Astrophysics Data System (ADS)

    Kwicklis, Edward; Farnham, Irene

    2014-09-01

    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 36Cl/Cl estimated with these 14C ages with published records of meteoric 36Cl/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.

  1. The use of chlorine isotope measurements to trace water movements at Yucca Mountain

    SciTech Connect

    Norris, A.E.

    1989-08-01

    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 36}Cl 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 36}Cl background that must be taken into account for proper interpretation of the {sup 36}Cl interpretation of the {sup 36}Cl results. Similarly, the {sup 36}Cl measured in water from the saturated zone requires additional work for correct interpretation. Fallout of {sup 36}Cl from nuclear weapons tests between 1952 and 1962 provided a tracer for an infiltration study. Measurements of the {sup 36}Cl bomb pulse in tuffs from the unsaturated zone show potential for tracing recent water flow in faults and fractures. 5 refs.

  2. Long-term {alpha}- and spontaneous fission measurement of a Rf/Db sample chemically prepared in a {sup 48}Ca on {sup 243}Am experiment

    SciTech Connect

    Dressler, Rugard; Eichler, Robert; Schumann, Dorothea; Shishkin, Sergey

    2009-05-15

    Results from long-term measurements of a chemically separated Db/Rf sample prepared from the products of a {sup 48}Ca on {sup 243}Am irradiation are presented. The sample with the highest spontaneous fission activity out of eight samples produced in the course of chemical experiments performed in 2004 was selected for these measurements. We conclude that there is no evidence for SF-decay originating from heavy actinide isotopes in this sample. Hence, it is appropriate to assign the SF-events observed in this experiment to decay products of {sup 288}115.

  3. Measurement of the Am241(n,2n) reaction cross section from 7.6 MeV to 14.5 MeV

    NASA Astrophysics Data System (ADS)

    Tonchev, A. P.; Angell, C. T.; Boswell, M.; Crowell, A. S.; Fallin, B.; Hammond, S.; Howell, C. R.; Hutcheson, A.; Karwowski, H. J.; Kelley, J. H.; Pedroni, R. S.; Tornow, W.; Becker, J. A.; Dashdorj, D.; Kenneally, J.; Macri, R. A.; Stoyer, M. A.; Wu, C. Y.; Bond, E.; Chadwick, M. B.; Fitzpatrick, J.; Kawano, T.; Rundberg, R. S.; Slemmons, A.; Vieira, D. J.; Wilhelmy, J. B.

    2008-05-01

    The (n,2n) cross section of the radioactive isotope Am241 (T1/2=432.6 y) has been measured in the incident neutron energy range from 7.6 to 14.5 MeV in steps of a few MeV using the activation technique. Monoenergetic neutron beams were produced via the H2(d,n)He3 reaction by bombarding a pressurized deuterium gas cell with an energetic deuteron beam at the TUNL 10-MV Van de Graaff accelerator facility. The induced γ-ray activity of Am240 was measured with high-resolution HPGe detectors. The cross section was determined relative to Al, Ni, and Au neutron activation monitor foils, measured in the same geometry. Good agreement is obtained with previous measurements at around 9 and 14 MeV, whereas for a large discrepancy is observed when our data are compared to those reported by Perdikakis near 11 MeV. Very good agreement is found with the END-B/VII evaluation, whereas the JENDL-3.3 evaluation is in fair agreement with our data.

  4. Neutron-induced fission cross section measurement of 233U, 241Am and 243Am in the energy range 0.5 MeV En 20 MeV at nTOF at CERN

    SciTech Connect

    Belloni, F.; Milazzo, P. M.; Calviani, M.; Colonna, N.; Mastinu, P. F.; Abbondanno, U.; Aerts, G.; Alvarez, H.; Alvarez-Velarde, F.; Andriamonje, S.; Andrzejewski, J.; Assimakopoulos, P. A.; Audouin, L.; Barbagallo, M.; Baumann, P.; Becvar, F.; Berthoumieux, E.; Calvino, F.; Cerutti, F.; Cano-Ott, D.; Capote, R.; Carrapico, C.; Carrillo de Albornoz, A.; Cennini, P.; Chepel, V.; Chiaveri, E.; Cortes, G.; Couture, A.; Cox, J.; Dahlfors, M.; David, S.; Dillmann, I.; Dolfini, R.; Domingo-Pardo, C.; Koehler, Paul; The n_TOF Collaboration,

    2012-01-01

    Neutron-induced fission cross section measurements of 233U, 243Am and 241Am relative to 235U have been carried out at the neutron time-of-flight facility n TOF at CERN. A fast ionization chamber has been employed. All samples were located in the same detector; therefore the studied elements and the reference 235U target are subject to the same neutron beam.

  5. Assessment of the neutron emission anisotropy factor of a sealed AmBe source by means of measurements and Monte Carlo simulations

    NASA Astrophysics Data System (ADS)

    Loreti, S.; Pietropaolo, A.

    2015-10-01

    The neutron emission anisotropy factor of a sealed Americium-Beryllium source is experimentally determined and compared to Monte Carlo simulations. The measurements were done at the Italian Institute for Metrology of Ionizing Radiations using a long counter neutron detector and a "X.3" type AmBe sealed neutron source. Experimental data are compared to simulations performed with the MCNP code where the precise structure of the source is taken into account starting from its technical design. The contributions of the single structural parts are described to point out the effective sources of the emission anisotropy.

  6. Measurement of the neutron-induced fission cross-section of 243Am relative to 235U from 0.5 to 20 MeV

    NASA Astrophysics Data System (ADS)

    Belloni, F.; Calviani, M.; Colonna, N.; Mastinu, P.; Milazzo, P. M.; Abbondanno, U.; Aerts, G.; Álvarez, H.; Alvarez-Velarde, F.; Andriamonje, S.; Andrzejewski, J.; Audouin, L.; Badurek, G.; Barbagallo, M.; Baumann, P.; Bečvář, F.; Berthoumieux, E.; Calviño, F.; Cano-Ott, D.; Capote, R.; Carrapiço, C.; Cennini, P.; Chepel, V.; Chiaveri, E.; Cortes, G.; Couture, A.; Cox, J.; Dahlfors, M.; David, S.; Dillmann, I.; Domingo-Pardo, C.; Dridi, W.; Duran, I.; Eleftheriadis, C.; Embid-Segura, M.; Ferrari, A.; Ferreira-Marques, R.; Fujii, K.; Furman, W.; Goncalves, I.; Gonzalez-Romero, E.; Goverdovski, A.; Gramegna, F.; Guerrero, C.; Gunsing, F.; Haas, B.; Haight, R.; Heil, M.; Herrera-Martinez, A.; Igashira, M.; Jericha, E.; Käppeler, F.; Kadi, Y.; Karadimos, D.; Karamanis, D.; Kerveno, M.; Koehler, P.; Kossionides, E.; Krtička, M.; Lamboudis, C.; Leeb, H.; Lindote, A.; Lopes, I.; Lozano, M.; Lukic, S.; Marganiec, J.; Marrone, S.; Martínez, T.; Massimi, C.; Meaze, M. H.; Mengoni, A.; Moreau, C.; Mosconi, M.; Neves, F.; Oberhummer, H.; O'Brien, S.; Pancin, J.; Papachristodoulou, C.; Papadopoulos, C.; Paradela, C.; Patronis, N.; Pavlik, A.; Pavlopoulos, P.; Perrot, L.; Pigni, M. T.; Plag, R.; Plompen, A.; Plukis, A.; Poch, A.; Praena, J.; Pretel, C.; Quesada, J.; Rauscher, T.; Reifarth, R.; Rosetti, M.; Rubbia, C.; Rudolf, G.; Rullhusen, P.; Salgado, J.; Santos, C.; Sarchiapone, L.; Savvidis, I.; Stephan, C.; Tagliente, G.; Tain, J. L.; Tarrio, D.; Tassan-Got, L.; Tavora, L.; Terlizzi, R.; Vannini, G.; Vaz, P.; Ventura, A.; Villamarin, D.; Vincente, M. C.; Vlachoudis, V.; Vlastou, R.; Voss, F.; Walter, S.; Wiescher, M.; Wisshak, K.

    2011-12-01

    The ratio of the neutron-induced fission cross-sections of 243Am and 235U was measured in the energy range from 0.5 to 20 MeV with uncertainties of ≈ 4%. The experiment was performed at the CERN n_TOF facility using a fast ionization chamber. With the good counting statistics that could be achieved thanks to the high instantaneous flux and the low backgrounds, the present results are useful for resolving discrepancies in previous data sets and are important for future reactors with improved fuel burn-up.

  7. Actinides AMS at CIRCE and 236U and Pu measurements of structural and environmental samples from in and around a mothballed nuclear power plant

    NASA Astrophysics Data System (ADS)

    De Cesare, M.; Fifield, L. K.; Sabbarese, C.; Tims, S. G.; De Cesare, N.; D'Onofrio, A.; D'Arco, A.; Esposito, A. M.; Petraglia, A.; Roca, V.; Terrasi, F.

    2013-01-01

    Accelerator mass spectrometry (AMS) is presently the most sensitive technique for the measurement of long-lived actinides, e.g. 236U and 239Pu. A new actinide line is in operation at the Center for Isotopic Research on Cultural and Environmental heritage (CIRCE) in Caserta, Italy. Using the actinide line a uranium mass sensitivity of around 4 μg has been reached measuring with a 16-strip silicon detector, and a 239Pu background level of below 0.1 fg has been obtained. In this work we also discuss preliminary results for environmental and structural samples from in and around the Garigliano nuclear power plant (GNPP), presently in the decommissioning phase. Measurements on environmental samples from the vicinity of the plant allow the assessment of contamination, if any, over the years. Measurements of structural samples from the plant are relevant to the optimization of the decommissioning program for the GNPP.

  8. Purdue Rare Isotope Measurement Laboratory

    NASA Astrophysics Data System (ADS)

    Caffee, M.; Elmore, D.; Granger, D.; Muzikar, P.

    2002-12-01

    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), 26Al (.702 My), 36Cl (.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.

  9. Tritium AMS for biomedical applications

    SciTech Connect

    Roberts, M.L.; Velsko, C.; Turteltaub, K.W.

    1993-08-01

    We are developing {sup 3}H-AMS to measure {sup 3}H activity of mg-sized biological samples. LLNL has already successfully applied {sup 14}C AMS to a variety of problems in the area of biomedical research. Development of {sup 3}H AMS would greatly complement these studies. The ability to perform {sup 3}H AMS measurements at sensitivities equivalent to those obtained for {sup 14}C will allow us to perform experiments using compounds that are not readily available in {sup 14}C-tagged form. A {sup 3}H capability would also allow us to perform unique double-labeling experiments in which we learn the fate, distribution, and metabolism of separate fractions of biological compounds.

  10. International key comparison of measurements of neutron source emission rate (1999-2005): CCRI(III)-K9.AmBe

    NASA Astrophysics Data System (ADS)

    Roberts, N. J.; Jones, L. N.; Wang, Z.; Liu, Y.; Wang, Q.; Chen, X.; Luo, H.; Rong, C.; Králik, M.; Park, H.; Choi, K. O.; Pereira, W. W.; da Fonseca, E. S.; Cassette, P.; Dewey, M. S.; Moiseev, N. N.; Kharitonov, I. A.

    2011-01-01

    Section III (neutron measurements) of the Comité Consultatif des Rayonnements Ionisants, CCRI, conducted a key comparison of primary measurements of the neutron emission rate of an 241Am-Be(α,n) radionuclide source. A single 241Am-Be(α,n) source was circulated to all the participants between 1999 and 2005. Eight laboratories participated—the CIAE (China), CMI (Czech Republic), KRISS (Republic of Korea), LNMRI (Brazil), LNE-LNHB (France), NIST (USA), NPL (UK) and the VNIIM (Russian Federation)—with the NPL making their measurements at the start and repeating them near the end of the exercise to verify the stability of the source. Each laboratory reported the emission rate into 4π sr together with a detailed uncertainty budget. All participants used the manganese bath technique, with the VNIIM also making measurements using an associated particle technique. The CMI, KRISS, VNIIM, and later the NPL, also measured the anisotropy of the source although this was not a formal part of the comparison. The first draft report was released in May 2006 and having been discussed and modified by the participants and subsequently reviewed by the CCRI(III), the present paper is now the final report of the comparison. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI Section III, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

  11. 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.

    PubMed

    Dołęga, Diana; Mikuli, Edward; Chruszcz-Lipska, Katarzyna

    2012-12-01

    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.

  12. Variations in AmLi source spectra and their estimation utilizing the 5 Ring Multiplicity Counter

    NASA Astrophysics Data System (ADS)

    Weinmann-Smith, R.; Beddingfield, D. H.; Enqvist, A.; Swinhoe, M. T.

    2017-06-01

    Active-mode assay systems are widely used for the safeguards of uranium items to verify compliance with the Non-Proliferation Treaty. Systems such as the Active-Well Coincidence Counter (AWCC) and the Uranium Neutron Coincidence Collar (UNCL) use americium-lithium (AmLi) neutron sources to induce fissions which are measured to determine the sample mass. These systems have historically relied on calibrations derived from well-defined standards. Recently, restricted access to standards or more difficult measurements have resulted in a reliance on modeling and simulation for the calibration of systems, which introduces potential simulation biases. The AmLi source energy spectra commonly used in the safeguards community do not accurately represent measurement results and the spectrum uncertainty can represent a large contribution to the total modeling uncertainty in active-mode systems. The 5-Ring Multiplicity Counter (5RMC) has been used to measure 17 AmLi sources. The measurements showed a significant spectral variation between different sources. Utilization of a spectrum that is specific to an individual source or a series of sources will give improved results over historical general spectra when modeling AmLi sources. Candidate AmLi neutron spectra were calculated in MCNP and SOURCES4C for a range of physical AmLi characteristics. The measurement and simulation data were used to fit reliable and accurate AmLi spectra for use in the simulation of active-mode systems. Spectra were created for average Gammatron C, Gammatron N, and MRC series sources, and for individual sources. The systematic uncertainty introduced by physical aspects of the AmLi source were characterized through simulations. The accuracy of spectra from the literature was compared.

  13. Measuring transfer of 14C-PCB from maternal diet to milk in a goat model using an accelerator mass spectrometer (AMS)

    NASA Astrophysics Data System (ADS)

    Janle, E.; Sojka, J.; Jackson, G. S.; Lachcik, P.; Einstien, J. A.; Santerre, C. R.

    2007-06-01

    Environmental pollutants pose a substantial risk to nursing infants. Many of these toxicants (i.e. PCBs, PBDEs, mercury) are passed from the maternal diet to the nursing infant in breast milk. Determining the toxicokinetics has been difficult to measure due to ethical limitations. Since extremely small amounts of 14C can be measured using Accelerator Mass Spectrometry (AMS), a goat model was used to establish a minimum oral dose of 14C-labeled PCB (2,2‧,4,4‧,5,5‧-hexachlorobiphenyl-UL-14C) that could be given to a lactating animal and traced into the milk. An oral dose of 66 nCi/kg body weight (1.84 μg PCB/kg bw) was administered. Plasma and milk samples were collected for 2 months after dosing. The concentration of 14C label reached a peak value of 1.71 ng/ml PCB equivalents in the milk on day 2 and then declined to about 135 pg/ml PCB equivalents in the milk at 3 weeks. A second goat was administered a smaller dose (22 nCi/kg bw; 616 ng PCB/kg bw). A peak concentration of 485 pg PCB equivalents/ml milk occurred at 3 days and declined to 77.6 pg PCB equivalents/ml milk by 3 weeks. Our results indicated that an even lower dosage of labeled-PCB could be used due to the extreme sensitivity of AMS measurement. Extrapolating from current data it is estimated that the dose could be reduced by a factor of 20 (31 ng PCB/kg bw; 1.1 nCi/kg bw) and still be detectable after 2 months. Thus, the potential exists for developing protocols for studying toxicokinetics in humans using radiologically- and toxicologically-benign doses of labeled environmental toxicants.

  14. Measurement of the neutron-induced fission cross-section of 241Am at the time-of-flight facility n_TOF

    NASA Astrophysics Data System (ADS)

    Belloni, F.; Calviani, M.; Colonna, N.; Mastinu, P.; Milazzo, P. M.; Abbondanno, U.; Aerts, G.; Álvarez, H.; Alvarez-Velarde, F.; Andriamonje, S.; Andrzejewski, J.; Audouin, L.; Badurek, G.; Barbagallo, M.; Baumann, P.; Bečvář, F.; Berthoumieux, E.; Calviño, F.; Cano-Ott, D.; Capote, R.; Carrapiço, C.; Cennini, P.; Chepel, V.; Chiaveri, E.; Cortes, G.; Couture, A.; Cox, J.; Dahlfors, M.; David, S.; Dillmann, I.; Domingo-Pardo, C.; Dridi, W.; Duran, I.; Eleftheriadis, C.; Embid-Segura, M.; Ferrari, A.; Ferreira-Marques, R.; Fujii, K.; Furman, W.; Goncalves, I.; Gonzalez-Romero, E.; Goverdovski, A.; Gramegna, F.; Guerrero, C.; Gunsing, F.; Haas, B.; Haight, R.; Heil, M.; Herrera-Martinez, A.; Igashira, M.; Jericha, E.; Käppeler, F.; Kadi, Y.; Karadimos, D.; Karamanis, D.; Kerveno, M.; Koehler, P.; Kossionides, E.; Krtička, M.; Lamboudis, C.; Leeb, H.; Lindote, A.; Lopes, I.; Lozano, M.; Lukic, S.; Marganiec, J.; Marrone, S.; Martínez, T.; Massimi, C.; Meaze, M. H.; Mengoni, A.; Moreau, C.; Mosconi, M.; Neves, F.; Oberhummer, H.; O'Brien, S.; Papachristodoulou, C.; Papadopoulos, C.; Paradela, C.; Patronis, N.; Pavlik, A.; Pavlopoulos, P.; Perrot, L.; Pigni, M. T.; Plag, R.; Plompen, A.; Plukis, A.; Poch, A.; Praena, J.; Pretel, C.; Quesada, J.; Rauscher, T.; Reifarth, R.; Rosetti, M.; Rubbia, C.; Rudolf, G.; Rullhusen, P.; Salgado, J.; Santos, C.; Sarchiapone, L.; Savvidis, I.; Stephan, C.; Tagliente, G.; Tain, J. L.; Tarrio, D.; Tassan-Got, L.; Tavora, L.; Terlizzi, R.; Vannini, G.; Vaz, P.; Ventura, A.; Villamarin, D.; Vincente, M. C.; Vlachoudis, V.; Vlastou, R.; Voss, F.; Walter, S.; Wiescher, M.; Wisshak, K.

    2013-01-01

    The neutron-induced fission cross-section of 241Am has been measured relative to the standard fission cross-section of 235U between 0.5 and 20MeV. The experiment was performed at the CERN n_TOF facility. Fission fragments were detected by a fast ionization chamber by discriminating against the α-particles from the high radioactivity of the samples. The high instantaneous neutron flux and the low background of the n_TOF facility enabled us to obtain uncertainties of ≈ 5%. With the present results it was possible to resolve discrepancies between previous data sets and to confirm current evaluations, thus providing important information for design studies of future reactors with improved fuel burn-up.

  15. Cosmogenic 36Cl exposure ages reveal a 9.3 ka BP glacier advance and the Late Weichselian-Early Holocene glacial history of the Drangajökull region, northwest Iceland

    NASA Astrophysics Data System (ADS)

    Brynjólfsson, Skafti; Schomacker, Anders; Ingólfsson, Ólafur; Keiding, Jakob K.

    2015-10-01

    We present twenty-four new cosmogenic isotope (36Cl) 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. Old36Cl 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

  16. Sci-Sat AM: Brachy - 04: Neutron production around a radiation therapy linac bunker - monte carlo simulations and physical measurements.

    PubMed

    Khatchadourian, R; Davis, S; Evans, M; Licea, A; Seuntjens, J; Kildea, J

    2012-07-01

    Photoneutrons are a major component of the equivalent dose in the maze and near the door of linac bunkers. Physical measurements and Monte Carlo (MC) calculations of neutron dose are key for validating bunker design with respect to health regulations. We attempted to use bubble detectors and a (3) He neutron spectrometer to measure neutron equivalent dose and neutron spectra in the maze and near the door of one of our bunkers. We also ran MC simulations with MCNP5 to measure the neutron fluence in the same region. Using a point source of neutrons, a Clinac 1800 linac operating at 10 MV was simulated and the fluence measured at various locations of interest. We describe the challenges faced when measuring dose with bubble detectors in the maze and the complexity of photoneutron spectrometry with linacs operating in pulsed mode. Finally, we report on the development of a userfriendly GUI for shielding calculations based on the NCRP 151 formalism. © 2012 American Association of Physicists in Medicine.

  17. The Radiolysis of AmVI Solutions

    SciTech Connect

    Bruce J. Mincher

    2013-06-01

    The reduction of bismuthate-produced AmVI by 60Co gamma-rays was measured using post-irradiation UV/Vis spectroscopy. The reduction of AmVI by radiolysis was rapid, producing AmV as the sole product. Relatively low absorbed doses in the ~0.3 kGy range quantitatively reduced a solution of 2.5 x 10-4 M AmVI. The addition of bismuthate to samples during irradiation did not appear to protect AmVI from radiolytic reduction during these experiments. It was also shown here that AmV is very stable toward radiation. The quantitative reduction of the AmVI concentration here corresponds to 1.4 hours of exposure to a process solution, however the actual americium concentrations will be higher and the expected contact times short when using centrifugal contactors. Thus, the reduction rate found in these initial experiments may not be excessive.

  18. Inner gorges incision history: A proxy for deglaciation? Insights from Cosmic Ray Exposure dating (10Be and 36Cl) of river-polished surfaces (Tinée River, SW Alps, France)

    NASA Astrophysics Data System (ADS)

    Rolland, Y.; Petit, C.; Saillard, M.; Braucher, R.; Bourlès, D.; Darnault, R.; Cassol, D.

    2017-01-01

    10Be and 36Cl 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.

  19. ESTIMATION OF NEUTRON SCATTER CORRECTION FOR CALIBRATION OF PERSONNEL DOSIMETER AND DOSERATEMETER AGAINST 241Am-Be SOURCE-MONTE CARLO SIMULATION AND MEASUREMENTS.

    PubMed

    Dawn, Sandipan; Bakshi, A K; Sathian, Deepa; Selvam, T Palani

    2016-10-07

    Neutron scatter contributions as a function of distance along the transverse axis of (241)Am-Be source were estimated by three different methods such as shadow cone, semi-empirical and Monte Carlo. The Monte Carlo-based FLUKA code was used to simulate the existing room used for the calibration of CR-39 detector as well as LB6411 doseratemeter for selected distances from (241)Am-Be source. The modified (241)Am-Be spectra at different irradiation geometries such as at different source detector distances, behind the shadow cone, at the surface of the water phantom were also evaluated using Monte Carlo calculations. Neutron scatter contributions, estimated using three different methods compare reasonably well. It is proposed to use the scattering correction factors estimated through Monte Carlo simulation and other methods for the calibration of CR-39 detector and doseratemeter at 0.75 and 1 m distance from the source.

  20. Heat capacities and thermal conductivities of AmO 2 and AmO 1.5

    NASA Astrophysics Data System (ADS)

    Nishi, Tsuyoshi; Itoh, Akinori; Ichise, Kenichi; Arai, Yasuo

    2011-07-01

    The thermal diffusivity of AmO 2 was measured from 473 to 773 K and that of AmO 1.5 between 473 and 1373 K using a laser flash method. The enthalpy increment of AmO 2 was measured from 335 to 1081 K and that of AmO 1.5 between 335 and 1086 K using drop calorimetry. The heat capacities of AmO 2 and AmO 1.5 were derived from the enthalpy increment measurements. The thermal conductivity was determined from the measured thermal diffusivity, heat capacity and bulk density. The heat capacities of AmO 2 was found larger than that of AmO 1.5. The thermal conductivities of AmO 2 and AmO 1.5 were found to decrease with increasing temperature in the investigated temperature range. The thermal conductivity of AmO 1.5 with A -type hexagonal structure was smaller than that of AmO 2 with C-type fluorite structure but larger than that of sub-stoichiometric AmO 1.73.

  1. AMS-02 as a Space Weather Observatory

    NASA Astrophysics Data System (ADS)

    Whitman, K.; Bindi, V.; Chati, M.; Consolandi, C.; Corti, C.

    2013-12-01

    The Alpha Magnetic Spectrometer (AMS-02) is a state-of-the-art space detector that measures particles in the energy range of hundreds of MeV to a few TeV. AMS-02 has been installed onboard of the International Space Station (ISS) since May 2011 where it will operate for the duration of the station. To date, there is an abundance of space-based solar data collected in the low energy regimes, whereas there are very few direct measurements of higher energy particles available. AMS-02 is capable of measuring arrival time and composition of the highest energy SEPs in space. It is crucial to build a better knowledge base regarding the most energetic and potentially harmful events. We are currently developing a program to employ AMS-02 as a real-time space weather observatory. SEPs with higher energies are usually accelerated during a short period of time and they are the first particles to reach the Earth. AMS-02, measuring these highest energy SEPs, can alert the onset of an SEP event. During the past two years of operation, we have identified two main quantities in AMS-02 that are particularly sensitive to the arrival of SEPs: the detector livetime and the transition radiation detector (TRD) event size. By monitoring the detector livetime and the TRD event size, AMS-02 can pinpoint in real-time the arrival of SEPs inside the Earth's magnetosphere operating as a space weather detector.

  2. AMS Prototyping Activities

    NASA Technical Reports Server (NTRS)

    Burleigh, Scott

    2008-01-01

    This slide presentation reviews the activity around the Asynchronous Message Service (AMS) prototype. An AMS reference implementation has been available since late 2005. It is aimed at supporting message exchange both in on-board environments and over space links. The implementation incoroporates all mandatory elements of the draft recommendation from July 2007: (1) MAMS, AMS, and RAMS protocols. (2) Failover, heartbeats, resync. (3) "Hooks" for security, but no cipher suites included in the distribution. The performance is reviewed, and a Benchmark latency test over VxWorks Message Queues is shown as histograms of a count vs microseconds per 1000-byte message

  3. AMS Prototyping Activities

    NASA Technical Reports Server (NTRS)

    Burleigh, Scott

    2008-01-01

    This slide presentation reviews the activity around the Asynchronous Message Service (AMS) prototype. An AMS reference implementation has been available since late 2005. It is aimed at supporting message exchange both in on-board environments and over space links. The implementation incoroporates all mandatory elements of the draft recommendation from July 2007: (1) MAMS, AMS, and RAMS protocols. (2) Failover, heartbeats, resync. (3) "Hooks" for security, but no cipher suites included in the distribution. The performance is reviewed, and a Benchmark latency test over VxWorks Message Queues is shown as histograms of a count vs microseconds per 1000-byte message

  4. The characteristics of PM1.0 for aircraft measurement case study using ToF-AMS for pre-campaign KORUS-AQ

    NASA Astrophysics Data System (ADS)

    Soo, C. J.

    2015-12-01

    Jinsoo Choi, Jinsoo Park, Joonyoung Ahn, Sangdeok Lee, Hyunjae Kim, Jun Oh, Youdeog Hong, Jihyung Hong, TaeHyeng Lee1Air Quality Division, National Institute of Environmental Research, Korea1Department of Environmental Science, Hankuk University of Foreign Studies, KoreaFor the Pre-KORUS-AQ Campaign during the period from May 18 to June 13 2015, aircraft observations were conducted: four times over the Yellow Sea and three times above Seoul Metropolitan Area (SMA). Aerosol (PM1.0) chemical composition and particles size distribution from 50 to 1000 nm were measured and analyzed using ToF-AMS installed the airplane (Kingair-C90GT, USA) in semi-real time. Concentrations of CO and the number of particles were measured as well. To analyze the aerosol's spatial and vertical characteristics, 5 flight paths were designed and the main paths were a cross over above SMA and spatial and vertical profile paths over the Yellow Sea. The flight distance varied from 600 to 900km and the velocity was kept at around 200 to 250 km/hr. On June 13 2015, the sky in SMA was densely fogged and the PM concentrations were relatively higher than usual. As for concentrations of main fine particles, Sulfate was 6.1 mg/m3, Organic 20.7 mg/m3, Ammonium 2.9 mg/m3 and Nitrate 2.9 mg/m3. Group of organic components consisted of 38.3% CxHy, 30.4% CxHyO1, 27.4% CxHyO2, 2.9% CxHyNp and 1.0% CxHyOzNp, and the proportion of oxidation group was 57.9%. As for CxHyO1 and CxHyO2 groups that are generated from decomposition process of oxidized organic compounds and closely related to SOA, the concentrations were 1.5 times higher than CxHy group's that is related with POA; it is considered that the high concentration on the 13th was highly affected by SOA. In the morning of the same day, aircraft measurements were conducted at the altitude between 600 and 2,700m above the Yellow Sea level, which revealed measurements of Sulfate 4.8 mg/m3, Organic 35.8 mg/m3, Ammonium 3.0 mg/m3 and Nitrate 3.7 mg/m3; these are

  5. AMS in Phytonutrition

    SciTech Connect

    Dueker, S R; Buchholz, B A

    2003-08-26

    As public interest in phytonutrition continues to increase, the result will be an augmented demand for extensive phytochemical research. The fact that foods are inherently phytochemically complex dictates a need to apply scientific techniques, which can detect synergistic interaction among the many active principles and adjuvant substances in the plant, and furthermore, modify the activities of these components. As illustrated by the experiments discussed in this presentation, the advantages of AMS are unique and extensive. These advantages are best summarized by Dr. John Vogel, an originator of biological AMS experimentation: ''AMS brings (at least) three advantages to biochemical tracing: high sensitivity for finding low probability events or for use of physiologic-sized doses; small sample sizes for painless biopsies or highly specific biochemical separations; and reduction of overall radioisotope exposures, inventories, and waste streams.'' AMS opens the door to increased phytochemical tracing in humans to obtain biochemical data concerning human health at dietary relevant levels of exposure. AMS, thus, obviates the need for uncertain extrapolations from animal models, which express marginal relevance to human metabolism. The unparalleled capabilities and benefits of AMS will undoubtedly establish this particular MS technique as an important analytical tool in phytochemical research.

  6. The electronics for the AMS-02 calorimeter

    NASA Astrophysics Data System (ADS)

    Cervelli, F.; Di Falco, S.; Incagli, M.; Vannini, C.; Magazzù, C.; Pedreschi, E.; Piendibene, M.; Pilo, F.; Spinella, F.

    2007-03-01

    AMS-02 is an astroparticle experiment that will operate on board of the ISS for a period of about three years. The main scientific goals of the experiment are the search for antimatter and dark matter and the study of gamma rays. In AMS-02 the Electromagnetic Calorimeter (ECAL) plays a key role for its high capability to measure e+, e- and gamma spectra and to discriminate electromagnetic showers from hadronic cascades [C. Adloff, et al., Performance of a 3D imaging electromagnetic calorimeter for the AMS02 space experiment, Proceedings of Calor 2004, Perugia, Italy. [1

  7. Latest AMS Results on Cosmic Ray fluxes

    NASA Astrophysics Data System (ADS)

    Bertucci, Bruna; AMS Collaboration

    2017-01-01

    AMS-02 is a wide acceptance high-energy physics experiment installed on the International Space Station in May 2011 and it has been operating continuously since then. Accurate studies of CR composition and energy spectra can be performed in AMS thanks to the unprecedented collected statistics - more than 90 billion events as of today - and the redundant measurements of particle charge, velocity, rigidity and energy. In this contribution we will present an overview of the latest results on anti-particles, electrons and light nuclei fluxes. On behalf of the AMS Collaboration.

  8. Depth profiling of Pu, 241Am and 137Cs in soils from southern Belarus measured by ICP-MS and alpha and gamma spectrometry.

    PubMed

    Boulyga, Sergei F; Zoriy, Myroslav; Ketterer, Michael E; Becker, J Sabine

    2003-08-01

    The depth distribution of plutonium, americium, and 137Cs originating from the 1986 accident at the Chernobyl Nuclear Power Plant (NPP) was investigated in several soil profiles in the vicinity from Belarus. The vertical migration of transuranic elements in soils typical of the 30 km relocation area around Chernobyl NPP was studied using inductively coupled plasma mass spectrometry (ICP-MS), alpha spectrometry, and gamma spectrometry. Transuranic concentrations in upper soil layers ranged from 6 x 10(-12) g g(-1) to 6 x 10(-10) g g(-1) for plutonium and from 1.8 x 10(-13) g g(-1) to 1.6 x 10(-11) g g(-1) for americium. These concentrations correspond to specific activities of (239+240)Pu of 24-2400 Bq kg(-1) and specific activity of 241Am of 23-2000 Bq kg(-1), respectively. Transuranics in turf-podzol soil migrate slowly to the deeper soil layers, thus, 80-95%, of radionuclide inventories were present in the 0-3 cm intervals of turf-podzol soils collected in 1994. In peat-marsh soil migration processes occur more rapidly than in turf-podzol and the maximum concentrations are found beneath the soil surface (down to 3-6 cm). The depth distributions of Pu and Am are essentially identical for a given soil profile. (239+240)Pu/137Cs and 241Am/137Cs activity ratios vary by up to a factor of 5 at some sites while smaller variations in these ratios were observed at a site close to Chernobyl, suggesting that 137Cs is dominantly particle associated close to Chernobyl but volatile species of 137Cs are of relatively greater importance at the distant sites.

  9. The first four years of the AMS-facility DREAMS: Status and developments for more accurate radionuclide data

    NASA Astrophysics Data System (ADS)

    Rugel, Georg; Pavetich, Stefan; Akhmadaliev, Shavkat; Enamorado Baez, Santiago Miguel; Scharf, Andreas; Ziegenrücker, René; Merchel, Silke

    2016-03-01

    DREAMS, the DREsden AMS-facility, is performing routine accelerator mass spectrometry of 10Be, 26Al, 36Cl, 41Ca, 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 36Cl 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, 26Al, and 41Ca 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.

  10. Elements in biological AMS

    SciTech Connect

    Vogel, J.S.; McAninch, J.; Freeman, S.

    1996-08-01

    AMS (Accelerator Mass Spectrometry) provides high detection sensitivity for isotopes whose half-lives are between 10 years and 100 million years. {sup 14}C is the most developed of such isotopes and is used in tracing natural and anthropogenic organic compounds in the Earth`s biosphere. Thirty-three elements in the main periodic table and 17 lanthanides or actinides have long lived isotopes, providing potential tracers for research in elemental biochemistry. Overlap of biologically interesting heavy elements and possible AMS tracers is discussed.

  11. AM 1316-241

    NASA Image and Video Library

    2008-04-24

    AM 1316-241 is made up of two interacting galaxies—a spiral galaxy on the left of the frame in front of an elliptical galaxy on the right of the frame. This image is part of a large collection of images of merging galaxies taken by NASA Hubble.

  12. The Schoolma'am.

    ERIC Educational Resources Information Center

    Donovan, Frances R.

    In the 1930s and reprinted in 1974, approximately 85 percent of the teachers in U.S. public schools were women--"schoolma'ams." This book provides a portrait of women teachers of that era, as well as a comprehensive overview of their lives, their careers, the conditions under which they taught in rural and urban schools, and the…

  13. How to convert biological carbon into graphite for AMS

    SciTech Connect

    Getachew, G; Kim, S; Burri, B J; Kelly, P B; Haack, K W; Ognibene, T J; Buchholz, B A; Vogel, J S; Modrow, J; Clifford, A J

    2006-07-27

    Isotope tracer studies, particularly radiocarbon measurements, play a key role in biological, nutritional, and environmental research. Accelerator mass spectrometry (AMS) is now the most sensitive detection method for radiocarbon, but AMS is not widely used in kinetic studies of humans. Part of the reason is the expense, but costs would decrease if AMS were used more widely. One component in the cost is sample preparation for AMS. Biological and environmental samples are commonly reduced to graphite before they are analyzed by AMS. Improvements and mechanization of this multi-step procedure is slowed by a lack of organized educational materials for AMS sample preparation that would allow new investigators to work with the technique without a substantial outlay of time and effort. We present a detailed sample preparation protocol for graphitizing biological samples for AMS and include examples of nutrition studies that have used this procedure.

  14. Variations in AmLi source spectra and their estimation utilizing the 5 Ring Multiplicity Counter

    DOE PAGES

    Weinmann-Smith, Robert; Beddingfield, David H.; Enqvist, Andreas; ...

    2017-02-28

    Active-mode assay systems are widely used for the safeguards of uranium items to verify compliance with the Non-Proliferation Treaty. Systems such as the Active-Well Coincidence Counter (AWCC) and the Uranium Neutron Coincidence Collar (UNCL) use americium-lithium (AmLi) neutron sources to induce fissions which are measured to determine the sample mass. These systems have historically relied on calibrations derived from well-defined standards. Recently, restricted access to standards or more difficult measurements have resulted in a reliance on modeling and simulation for the calibration of systems, which introduces potential simulation biases. Furthermore, the AmLi source energy spectra commonly used in the safeguardsmore » community do not accurately represent measurement results and the spectrum uncertainty can represent a large contribution to the total modeling uncertainty in active-mode systems.« less

  15. Alpha Magnetic Spectrometer (AMS) Overview

    NASA Image and Video Library

    The Alpha Magnetic Spectrometer (AMS) is flying to the station on STS-134. The AMS experiment is a state-of-the-art particle physics detector being operated by an international team composed of 60 ...

  16. Investigation of the 241Am(n ,2 n )240Am cross section

    NASA Astrophysics Data System (ADS)

    Kalamara, A.; Vlastou, R.; Kokkoris, M.; Diakaki, M.; Tsinganis, A.; Patronis, N.; Axiotis, M.; Lagoyannis, A.

    2016-01-01

    The 241Am(n ,2 n )240Am reaction cross section has been measured at four energies, 10.0, 10.4, 10.8, and 17.1 MeV, by means of the activation technique, relative to the 27Al(n ,α )24Na reaction reference cross section. Quasi-monoenergetic neutron beams were produced via the 2H(d ,n )3He and the 3H(d ,n )4He reactions at the 5.5 MV Tandem T11/25 accelerator laboratory of NCSR "Demokritos". The high purity 241Am targets were provided by JRC-IRMM, Geel, Belgium. The induced γ -ray activity of 240Am was measured with high-resolution high-purity germanium (HPGe) detectors. Auxiliary Monte Carlo simulations were performed with the mcnp code. The present results are in agreement with data obtained earlier and predictions obtained with the empire code.

  17. AMS results on positrons and antiprotons in cosmic rays

    NASA Astrophysics Data System (ADS)

    Kounine, Andrei; AMS Collaboration

    2017-01-01

    AMS-02 is a particle physics detector collecting data on the International Space Station since May 2011. Precision measurements of charged cosmic ray particles have been performed by AMS using a data sample of 85 billion cosmic ray events collected during the first five years of operations on the Station. The latest AMS results on the fluxes and flux ratios of the cosmic ray particles are presented with the emphasis on the measurements of positrons and antiprotons. They show unique features that require accurate theoretical interpretation as to their origin, be it from dark matter collisions or new astrophysical sources. On behalf of AMS.

  18. Absolute calibration of 10Be AMS standards

    NASA Astrophysics Data System (ADS)

    Nishiizumi, Kunihiko; Imamura, Mineo; Caffee, Marc W.; Southon, John R.; Finkel, Robert C.; McAninch, Jeffrey

    2007-05-01

    The increased detection sensitivity offered by AMS has dramatically expanded the utility of 10Be. As these applications become more sophisticated attention has focused on the accuracy of the 10Be standards used to calibrate the AMS measurements. In recent years it has become apparent that there is a discrepancy between two of the most widely used 10Be AMS standards, the ICN 10Be standard and the NIST 10Be standard. The ICN (ICN Chemical & Radioisotope Division) 10Be AMS standard was calibrated by radioactive decay counting. Dilutions, ranging from 5 × 10 -13 to 3 × 10 -1110Be/Be, have been prepared and are extensively used in many AMS laboratories. The NIST 10Be standard, prepared at the National Institute of Standards and Technology (NIST), is calibrated by mass spectrometric isotope ratio measurements. To provide an independent calibration of the 10Be standards we implanted a known number of 10Be atoms in both Si detectors and Be foil targets. The 10Be concentrations in these targets were measured by AMS. The results were compared with both the ICN and NIST AMS standards. Our 10Be measurements indicate that the 10Be/ 9Be isotopic ratio of the ICN AMS standard, which is based on a 10Be half-life of 1.5 × 10 6 yr, is 1.106 ± 0.012 times lower than the nominal value. Since the decay rate of the ICN standard is well determined, the decrease in 10Be/ 9Be ratio requires that the 10Be half-life be reduced to (1.36 ± 0.07) × 10 6 yr. The quoted uncertainty includes a ±5% uncertainty in the activity measurement carried out by ICN. In a similar fashion, we determined that the value of the NIST 10Be standard (SRM4325) is (2.79 ± 0.03) × 10 -1110Be/ 9Be, within error of the certified value of (2.68 ± 0.14) × 10 -11. The Lawrence Livermore National Laboratory (LLNL) internal standards were also included in this study. We conclude that the 9Be(n, γ) neutron cross section is 7.8 ± 0.23 mb, without taking into account the uncertainty in the neutron irradiation.

  19. Prelaunch Calibrations of the Clouds and the Earth's Radiant Energy System (CERES) Tropical Rainfall Measuring Mission and Earth Observing System Morning (EOS-AM1) Spacecraft Thermistor Bolometer Sensors

    NASA Technical Reports Server (NTRS)

    Lee, Robert B., III; Barkstrom, Bruce R.; Bitting, Herbert C.; Crommelynck, Dominique A. H.; Paden, Jack; Pandey, Dhirendra K.; Priestley, Kory J.; Smith, G. Louis; Thomas, Susan; Thornhill, K. Lee; Wilson, Robert S.

    1998-01-01

    The Clouds and the Earth's Radiant Energy System (CERES) spacecraft scanning thermistor bolometer sensors measure earth radiances in the broadband shortwave solar (O.3 - 5.0 micron and total (0.3 to 100 microns) spectral bands as well as in the 8-12 microns water vapor window spectral band. On November 27, 1997, the launch of the Tropical Rainfall Measuring Mission (TRMM) spacecraft placed the first set of CERES sensors into orbit, and 30 days later, the sensors initiated operational measurements of the earth radiance fields. In 1998, the Earth Observing System morning (EOS-AM1) spacecraft will place the second and third sensor sets into orbit. The prelaunch CERES sensors' count conversion coefficients (gains and zero-radiance offsets) were determined in vacuum ground facilities. The gains were tied radiometrically to the International Temperature Scale of 1990 (ITS-90). The gain determinations included the spectral properties (reflectance, transmittance, emittance, etc.) of both the sources and sensors as well as the in-field-of-view (FOV) and out-of-FOV sensor responses. The resulting prelaunch coefficients for the TRMM and EOS-AM1 sensors are presented. Inflight calibration systems and on-orbit calibration approaches are described, which are being used to determine the temporal stabilities of the sensors' gains and offsets from prelaunch calibrations through on-orbit measurements. Analyses of the TRMM prelaunch and on-orbit calibration results indicate that the sensors have retained their ties to ITS-90 at accuracy levels better than /- 0.3% between the 1995 prelaunch and 1997 on-orbit calibrations.

  20. Prelaunch Calibrations of the Clouds and the Earth's Radiant Energy System (CERES) Tropical Rainfall Measuring Mission and Earth Observing System Morning (EOS-AM1) Spacecraft Thermistor Bolometer Sensors

    NASA Technical Reports Server (NTRS)

    Lee, Robert B., III; Barkstrom, Bruce R.; Bitting, Herbert C.; Crommelynck, Dominique A. H.; Paden, Jack; Pandey, Dhirendra K.; Priestley, Kory J.; Smith, G. Louis; Thomas, Susan; Thornhill, K. Lee; hide

    1998-01-01

    The Clouds and the Earth's Radiant Energy System (CERES) spacecraft scanning thermistor bolometer sensors measure earth radiances in the broadband shortwave solar (O.3 - 5.0 micron and total (0.3 to 100 microns) spectral bands as well as in the 8-12 microns water vapor window spectral band. On November 27, 1997, the launch of the Tropical Rainfall Measuring Mission (TRMM) spacecraft placed the first set of CERES sensors into orbit, and 30 days later, the sensors initiated operational measurements of the earth radiance fields. In 1998, the Earth Observing System morning (EOS-AM1) spacecraft will place the second and third sensor sets into orbit. The prelaunch CERES sensors' count conversion coefficients (gains and zero-radiance offsets) were determined in vacuum ground facilities. The gains were tied radiometrically to the International Temperature Scale of 1990 (ITS-90). The gain determinations included the spectral properties (reflectance, transmittance, emittance, etc.) of both the sources and sensors as well as the in-field-of-view (FOV) and out-of-FOV sensor responses. The resulting prelaunch coefficients for the TRMM and EOS-AM1 sensors are presented. Inflight calibration systems and on-orbit calibration approaches are described, which are being used to determine the temporal stabilities of the sensors' gains and offsets from prelaunch calibrations through on-orbit measurements. Analyses of the TRMM prelaunch and on-orbit calibration results indicate that the sensors have retained their ties to ITS-90 at accuracy levels better than /- 0.3% between the 1995 prelaunch and 1997 on-orbit calibrations.

  1. Structural geology, petrofabrics and magnetic fabrics (AMS, AARM, AIRM)

    NASA Astrophysics Data System (ADS)

    Borradaile, Graham J.; Jackson, Mike

    2010-10-01

    Anisotropy of magnetic susceptibility (AMS) was recognized as a feature of minerals in 1899, and petrofabric-compatible AMS fabrics were reported from 1942-1958. Shortly thereafter, cleavage and mineral lineation were associated with the principal axes of the AMS ellipsoid. AMS is describable by a magnitude ellipsoid, somewhat similar in concept to the finite strain ellipsoid, with principal susceptibilities (κ MAX, κ INT, κ MIN) as its axes and their average value being the mean susceptibility (κ). Orientations of the AMS axes usually have a reasonably straightforward structural significance but their magnitudes are more difficult to interpret, being the result of mineral abundances and different mineral-AMS. The strain ellipsoid is dimensionless (i.e., of unit-volume) and readily compared from one outcrop to another but the AMS ellipsoid represents the anisotropy of a physical property. Thus, (κ) determines the relative importance of AMS for different specimens, or compared outcrops, or component AMS subfabrics. AMS provides a petrofabric tool, unlike any other, averaging and sampling the orientation-distribution of all minerals and all subfabrics in a specimen. Sophisticated laboratory techniques may isolate the AMS contributions of certain minerals from one another, and of certain subfabrics (e.g. depositional from tectonic). However, suitable data processing of the basic AMS measurements (κ MAX, κ INT, κ MIN magnitudes and orientations, and the mean susceptibility, κ) may provide the same information. Thus, AMS provides the structural geologist with a unique tool that may isolate the orientations of subfabrics of different origins (sedimentary, tectonic, tectonic overprints etc.).

  2. Latest AMS Results on elementary particles in cosmic rays

    NASA Astrophysics Data System (ADS)

    Kounine, Andrei; AMS Collaboration

    2017-01-01

    AMS-02 is a particle physics detector collecting data on the International Space Station since May 2011. Precision measurements of all elementary charged cosmic ray particles have been performed by AMS using a data sample of 85 billion cosmic ray events collected during the first five years of operations on the Station. The latest AMS results on the fluxes and flux ratios of the elementary cosmic ray particles are presented. They show unique features that require accurate theoretical interpretation as to their origin, be it from dark matter collisions or new astrophysical sources. On behalf of the AMS Collaboration.

  3. Compact AMS System At Yamagata University

    SciTech Connect

    Tokanai, Fuyuki; Kato, Kazuhiro; Anshita, Minoru; Izumi, Akihiro; Sakurai, Hirohisa; Saito, Tsugio

    2011-06-01

    A new compact accelerator mass spectrometry (AMS) system has been installed in the Kaminoyama research institute at Yamagata University. The AMS system is based on a 0.5 MV Pelletron accelerator developed by National Electrostatics Corp. The performance of the system was investigated using C series samples (C1-C8), standard samples (HOxII), and reagent graphite without any chemical treatment. The precision of {sup 14}C measurements for the standard samples is typically higher than 0.3%. The ratio of {sup 14}C to {sup 12}C is less than 6x10{sup -16} for the reagent graphite. In this paper, we present the performance of the new compact AMS system, as well as of the fully automated 20-reactor graphite lines equipped at the research institute.

  4. Thermal neutron capture cross-section and resonance integral measurements of 139La(n, γ)140La and 140Ce(n, γ)141Ce using a Am-Be neutron source

    NASA Astrophysics Data System (ADS)

    Panikkath, Priyada; Mohanakrishnan, P.

    2017-03-01

    Thermal neutron capture cross-sections and resonance integrals of 139La(n, γ)140La and 140Ce (n, γ)141Ce are measured with respect to reference reactions 197Au(n, γ)198Au and 55Mn(n, γ)56Mn using the neutron activation technique. Measurements are carried out using neutrons from an Am-Be source located inside a concrete bunker. Two different methods are used for determining self-shielding factors of activation foils as well as for finding the epithermal neutron spectrum shape factor. For 139 La with reference to 197 Au and 55 Mn the measured thermal cross sections are 9.24 ± 0.25 b and 9.28 ± 0.37 b, respectively, while the measured resonance integrals are 12.18 ± 0.67 b and 11.81 ± 0.94 b, respectively. For 140 Ce with reference to 197 Au and 55 Mn the measured thermal cross sections are 0.44 ± 0.01 b and 0.44 ± 0.02 b, respectively, while the measured resonance integrals are 0.55 ± 0.03 b and 0.54 ± 0.04 b, respectively. The present measurements are compared with earlier measurements and evaluations. Presently estimated values confirm the established 139La(n, γ)140La cross-sections. The presently measured thermal capture cross-section 140Ce(n, γ)141Ce , though lower than the evaluated data, is having higher accuracy compared to previous measurements with large uncertainties. The resonance integral measured is higher (like most previous measurements) than most evaluations requiring a revision of the evaluated data.

  5. "I Am Working-Class": Subjective Self-Definition as a Missing Measure of Social Class and Socioeconomic Status in Higher Education Research

    ERIC Educational Resources Information Center

    Rubin, Mark; Denson, Nida; Kilpatrick, Sue; Matthews, Kelly E.; Stehlik, Tom; Zyngier, David

    2014-01-01

    This review provides a critical appraisal of the measurement of students' social class and socioeconomic status (SES) in the context of widening higher education participation. Most assessments of social class and SES in higher education have focused on objective measurements based on the income, occupation, and education of students'…

  6. Hydrologic and geochemical controls on the transport of radionuclides in natural undisturbed arid environments as determined by accelerator mass spectrometry measurements

    SciTech Connect

    Nimz, G; Caffee, M W; McAninch, J

    2000-04-01

    This project developed techniques for measuring globally distributed radionuclides that occur today in extremely low abundances (''fallout'' from the era of atmospheric nuclear testing), and then applied these techniques to better understand the mechanisms by which radionuclides migrate. The techniques employ accelerator mass spectrometry (AMS), a relatively new analytical tool that permits this work to be conducted for the first time. The goal in this project was to develop AMS analytical techniques for {sup 129}I (fallout concentration: {approx} 10{sup 6} atoms/g) {sup 99}Tc ({approx} 10{sup 9} atoms/g), {sup 90}Sr ({approx}10{sup 7} atoms/gram soil), and {sup 93}Zr ({approx} 10{sup 9} atoms/g), and improved methods for {sup 36}Cl ({approx} 10{sup 9} atoms/g). As a demonstration of the analytical techniques, and as an investigation of identified problems associated with characterizing moisture and radionuclide movement in unsaturated desert soils, we developed a vadose zone research site at the Nevada Test Site. Our findings can be summarized as follows: (1) The distribution of chloride and {sup 36}Cl at the research site indicates that the widely-used ''chloride accumulation'' method for estimating moisture flux is erroneous; some mechanism for attenuation of chloride exists, violating an assumption of the accumulation method; (2) {sup 129}I is fractionated into several soil compartments that have varying migration abilities; the two most mobile can be tentatively identified as Fe/Mn oxyhydroxides and organic acids based on our sequential leaching techniques; (3) These most mobile constituents are capable of migrating at a rate greater than that of {sup 36}Cl, usually considered the most mobile solute in hydrologic systems; these constituents may be colloidal in character, of neutral surface charge, and therefore conservative in aqueous migration; (4) {sup 99}Tc is readily measurable by AMS, as we demonstrate by the first AMS {sup 99}Tc measurements of

  7. Mechanical Properties of AM Stainless Steel Parts and Repair Welds

    SciTech Connect

    Vogel, Sven C.; Carpenter, John S.

    2015-02-22

    Goals: Advance certification of AM materials and compare microstructure and its evolution during processing and deformation between AM fabricated and conventional steels. Deliverables achieved: Measured texture data for 17 steel samples on HIPPO, including material planned to be shocked in pRAD in FY16; quantified texture and austenite/ferrite phase fractions; and provide input data for deformation modeling.

  8. Welding of AM350 and AM355 steel

    NASA Technical Reports Server (NTRS)

    Davis, R. J.; Wroth, R. S.

    1967-01-01

    A series of tests was conducted to establish optimum procedures for TIG welding and heat treating of AM350 and AM355 steel sheet in thicknesses ranging from 0.010 inch to 0.125 inch. Statistical analysis of the test data was performed to determine the anticipated minimum strength of the welded joints.

  9. Measurement of long-lived radionuclides in surface soil around F1NPP accident site by Accelerator Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Miyake, Yasuto; Matsuzaki, Hiroyuki; Sasa, Kimikazu; Takahashi, Tsutomu

    2015-10-01

    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 36Cl (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, 36Cl is generated during reactor operation via neutron capture reaction of 35Cl, an impurity in the coolant or reactor component. Resulting 36Cl/Cl ratio within the reactor is thus much higher compared to that in environment. Similar to 129I, 36Cl 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. 36Cl/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 36Cl and 129I concentration was observed.

  10. Cross-cultural adaptation to Brazilian Portuguese of the Activity Measure for Post-Acute Care (AM-PAC) short forms for outpatients in rehabilitation.

    PubMed

    Souza, Mariana Angélica Peixoto De; Mancini, Marisa Cotta; Coster, Wendy Jane; Kirkwood, Renata Noce; Figueiredo, Elyonara Mello De; Sampaio, Rosana Ferreira

    2017-07-12

    The Activity Measure for Post-Acute Care was developed to evaluate the limitations of activities of adult individuals with different health conditions. To translate and cultural adapt the Activity Measure for Post-Acute Care short forms for outpatients into Portuguese-Brazilian, to verify the comprehension of the items and categories of the responses by users of the rehabilitation services and to analyze the reliability indices of the instrument. Translation and back-translation were conducted by two independent teams. Cognitive interviews (n=2) evaluated the comprehension of the translated version among patients. Item reliability and consistency was also investigated. There was conceptual equivalence between the translated and original versions. For some items, the information was modified in order to attend to the measurement units used in Brazil. Comparative analyses of the translated versions chose the most appropriate term to capture the English content. The few discrepancies identified in the back-translation were solved by consensus. The cognitive interviews detected few comprehension problems, which were solved by means of repetition of the item statement and use of examples to clarify the specificity of the information. The final translated short forms of the instrument showed excellent test-retest reliability and inter-examiner reliability indices, as well as high internal consistency. The Portuguese version of the Activity Measure for Post-Acute Care short forms will provide Brazilian clinicians and researchers with an up-to-date instrument for the evaluation of functioning of adults with various clinical conditions who attend outpatient rehabilitation settings. Copyright © 2017 Associação Brasileira de Pesquisa e Pós-Graduação em Fisioterapia. Publicado por Elsevier Editora Ltda. All rights reserved.

  11. Why Am I So Sad?

    MedlinePlus

    ... What Happens in the Operating Room? Why Am I So Sad? KidsHealth > For Kids > Why Am I So Sad? A A A What's in this ... ON THIS TOPIC My Pet Died - How Can I Feel Better? Five Steps for Fighting Stress What ...

  12. Am I Doing Anything Wrong?

    NASA Astrophysics Data System (ADS)

    Chang, Eun-Woo

    1998-04-01

    Absolutely not! Let me be more specific. Am I doing anything I do not want to do with my career? I don't think so. Am I satisfied? My initial career goal was to teach at a small four-year university and do research with undergraduate students. But I am more than satisfied with what I am doing now, and I am enjoying my job. It is true that many new and talented Ph.D.'s are currently looking for careers at two-year colleges instead of universities. Many people expect this trend will be even greater in the future. Surveys also show that younger people (20-30's) care a great deal about both family and career. Thus, a teaching job at a two-year college is ideal for them. It was quite a surprise to find that many of my friends, who are very talented in research, are now teaching at two-year colleges.

  13. 'Who am I?'.

    PubMed

    Schellinski, Kristina

    2014-04-01

    The dreams and existential questions of those, who came into being in order to replace a dead person, pivot around a central cry: 'Who am I?' If conceived, born or designated as a replacement child, such an individual may suffer-even as an adult-from a rarely recognized unconscious confusion of identity, compounded by grief and survivors' guilt. From before the child is born, the archetypal forces of death and life are joined in a fateful constellation; the soul of the replacement child bears the shadow of death from the very beginning of life. Hope for the replacement child lies in an emergence of true self as soul recreates original life. Analysis can help the replacement child experience a 'rebirth into true life', not as 'the one who returned', but as a psychologically newborn individual; the path of individuation countering the replacement child's identification with the dead. Jungian analysis offers unique concepts for understanding and healing the replacement child; C.G. Jung himself was born after two stillborn babies and an infant that lived only five days.

  14. High energy X-ray diffraction measurement of the superstructure reflection (100) for a creep deformed AM1 single crystal superalloy specimen

    SciTech Connect

    Royer, A.; Bastie, P.; Veron, M.

    1997-10-15

    Due to its importance for industrial applications, the microstructural behavior of single crystal nickel base superalloys as a function of the thermo-mechanical history of the material is the subject of many studies. However, some controversies remain concerning parameters which are driving the coarsening of {gamma}{prime} precipitates. In particular the role of the lattice parameter mismatch between the {gamma} and {gamma}{prime} phases (usually defined as {Delta}d/d = (a{gamma}{prime} {minus} a{gamma})/ where a{gamma}{prime} and a{gamma} represent respectively the lattice parameter value of the {gamma}{prime} and {gamma} phases) and of the internal stresses at the interfaces has to be clarified. An experiment was performed on a creep deformed sample using high energy synchrotron radiation and a Triple Crystal Diffractometer set-up (TCD) which allow nondestructive measurements and probe the bulk of the sample. With this method the superstructure reflection (100) was measured with a good accuracy and a reasonable statistics.

  15. Towards TCCON Tropics: Assessment and Measurements of Carbon and its Climate Impacts in Southeast Asia (T3AM C2lImA)

    NASA Astrophysics Data System (ADS)

    Morino, I.; Velazco, V. A.; Schwandner, F. M.; Macatangay, R. C.; Griffith, D. W. T.

    2015-12-01

    TCCON (Total Carbon Column Observing Network) measurements of CO2 and CH4 have been and are currently used extensively and globally for satellite validation, for comparison with atmospheric chemistry models and to study atmosphere-biosphere exchanges of carbon. With the global effort to cap greenhouse gas emissions, TCCON has become vital for validating satellite-based greenhouse gas data from past, current and future missions like Japanese GOSAT (Greenhouse Gas Observing SATellite) and GOSAT-2, NASA's OCO-2 (Orbiting Carbon Observatory-2) and OCO-3, ESA's Carbon Monitoring Satellite (CarbonSat), Chinese TanSat, and others. The lack of reliable validation data for the satellite-based greenhouse gas observing missions in the tropical regions is a common limitation in global carbon-cycle modeling studies that have a tropical component. The international CO2 modeling community have specified a requirement for "expansion of the CO2 observation network within the tropics" to reduce uncertainties in regional estimates of CO2 sources and sinks using atmospheric transport models. A TCCON site in the western tropical Pacific is a logical next step in obtaining additional knowledge that would greatly contribute to the understanding of the Earth's atmosphere and better constraining a major tropical region experiencing tremendous economic and population growth. Here, we present a complete site assessment for a possible TCCON site in the Philippines and our decision on the site where a new TCCON FTS will be installed. This site assessment was conducted in cooperation with the Energy Development Corporation (EDC, Philippines), National Institute for Environmental Studies (NIES, Japan), University of Wollongong (UoW, Australia), NASA's Jet Propulsion Laboratory (JPL), the University of the Philippines (UP-IESM), the TCCON science team, and the GOSAT-2 science team.

  16. Accelerator mass spectrometry (AMS) in plutonium analysis.

    PubMed

    Strumińska-Parulska, Dagmara I

    The paper summarizes the results of the (240)Pu/(239)Pu atomic ratio studies in atmospheric fallout samples collected in 1986 over Gdynia (Poland) as well as three Baltic fish species collected in 1997 using the accelerator mass spectrometry. A new generation of AMS has been developed during last years and this method is an efficient and good technique to measure long-lived radioisotopes in the environment and provides the most accurate determination of the atomic ratios between (240)Pu and (239)Pu. The nuclide compositions of plutonium in filter samples correspond to their means of production. AMS measurements of atmospheric fallout collected in April showed sufficient increase of the (240)Pu/(239)Pu atomic ratio from 0.28 from March to 0.47. Also such high increase of (240)Pu/(239)Pu atomic ratio, close to reactor core (240)Pu/(239)Pu atomic ratio, was observed in September and equaled 0.47.

  17. Status and plans for the PRIME Lab AMS facility

    NASA Astrophysics Data System (ADS)

    Elmore, D.; Ma, X.; Miller, T.; Mueller, K.; Perry, M.; Rickey, F.; Sharma, P.; Simms, P.; Lipschutz, M.; Vogt, S.

    1997-03-01

    The operation, status, performance, and upgrade plans for the Purdue Rare Isotope Measurement Laboratory (PRIME Lab) are described. The AMS system is in routine operation for all of the commonly-used AMS nuclides. Chemical preparation is being performed for all nuclides measured in many different matrices. Construction of a new injector and terminal stripper system is in progress; a fast-isotope-switching system is in the final design stage.

  18. Counting Statistics and Ion Interval Density in AMS

    SciTech Connect

    Vogel, J S; Ognibene, T; Palmblad, M; Reimer, P

    2004-08-03

    Confidence in the precisions of AMS and decay measurements must be comparable for the application of the {sup 14}C calibration to age determinations using both technologies. We confirmed the random nature of the temporal distribution of {sup 14}C ions in an AMS spectrometer for a number of sample counting rates and properties of the sputtering process. The temporal distribution of ion counts was also measured to confirm the applicability of traditional counting statistics.

  19. Resource for the Development of Biomedical Accelerator Mass Spectrometry (AMS)

    SciTech Connect

    Turteltaub, K. W.; Bench, G.; Buchholz, B. A.; Enright, H.; Kulp, K.; McCartt, A. D.; Malfatti, M.; Ognibene, T.; Loots, G.; Stewart, B. J.

    2016-04-08

    The NIH Research Resource for Biomedical AMS was originally funded at Lawrence Livermore National Laboratory in 1999 to develop and apply the technology of accelerator mass spectrometry (AMS) in broad- based biomedical research. The Resource’s niche is to fill needs for ultra high sensitivity quantitation when isotope-labeled agents are used. The Research Resource’s Technology Research and Development (TR&D) efforts will focus on the needs of the biomedical research community in the context of seven Driving Biomedical Projects (DBPs) that will drive the Center’s technical capabilities through three core TR&Ds. We will expand our present capabilities by developing a fully integrated HPLC AMS to increase our capabilities for metabolic measurements, we will develop methods to understand cellular processes and we will develop and validate methods for the application of AMS in human studies, which is a growing area of demand by collaborators and service users. In addition, we will continue to support new and ongoing collaborative and service projects that require the capabilities of the Resource. The Center will continue to train researchers in the use of the AMS capabilities being developed, and the results of all efforts will be widely disseminated to advance progress in biomedical research. Towards these goals, our specific aims are to:1.) Increase the value and information content of AMS measurements by combining molecular speciation with quantitation of defined macromolecular isolates. Specifically, develop and validate methods for macromolecule labeling, characterization and quantitation.2.) Develop and validate methods and strategies to enable AMS to become more broadly used in human studies. Specifically, demonstrate robust methods for conducting pharmacokinetic/pharmacodynamics studies in humans and model systems.3.) Increase the accessibility of AMS to the Biomedical research community and the throughput of AMS through direct coupling to separatory

  20. AMS with light nuclei at small accelerators

    NASA Astrophysics Data System (ADS)

    Stan-Sion, C.; Enachescu, M.

    2017-06-01

    AMS applications with lighter nuclei are presented. It will be shown how Carbon-14, Boron-10, Beryllium-10, and Tritium-3 can be used to provide valuable information in forensic science, environmental physics, nuclear pollution, in material science and for diagnose of the plasma confinement in fusion reactors. Small accelerators are reliable, efficient and possess the highest ion beam transmissions that confer high precision in measurements.

  1. AMS/DOE Graduate Fellowship

    SciTech Connect

    None None

    2011-06-15

    The American Meteorological Society (AMS) Fellowship Program was established in 1991. To date, AMS has awarded over 150 Fellowships. This five year DOE award provided for one Fellowship a year for five years. The objective of this program is to provide enough funding to a student so as to allow the student to focus solely on coursework requirements, thus allowing them to begin their research at an earlier date.

  2. Bioanalysis works in the IAA AMS facility: Comparison of AMS analytical method with LSC method in human mass balance study

    NASA Astrophysics Data System (ADS)

    Miyaoka, Teiji; Isono, Yoshimi; Setani, Kaoru; Sakai, Kumiko; Yamada, Ichimaro; Sato, Yoshiaki; Gunji, Shinobu; Matsui, Takao

    2007-06-01

    Institute of Accelerator Analysis Ltd. (IAA) is the first Contract Research Organization in Japan providing Accelerator Mass Spectrometry (AMS) analysis services for carbon dating and bioanalysis works. The 3 MV AMS machines are maintained by validated analysis methods using multiple control compounds. It is confirmed that these AMS systems have reliabilities and sensitivities enough for each objective. The graphitization of samples for bioanalysis is prepared by our own purification lines including the measurement of total carbon content in the sample automatically. In this paper, we present the use of AMS analysis in human mass balance and metabolism profiling studies with IAA 3 MV AMS, comparing results obtained from the same samples with liquid scintillation counting (LSC). Human samples such as plasma, urine and feces were obtained from four healthy volunteers orally administered a 14C-labeled drug Y-700, a novel xanthine oxidase inhibitor, of which radioactivity was about 3 MBq (85 μCi). For AMS measurement, these samples were diluted 100-10,000-fold with pure-water or blank samples. The results indicated that AMS method had a good correlation with LSC method (e.g. plasma: r = 0.998, urine: r = 0.997, feces: r = 0.997), and that the drug recovery in the excreta exceeded 92%. The metabolite profiles of plasma, urine and feces obtained with HPLC-AMS corresponded to radio-HPLC results measured at much higher radioactivity level. These results revealed that AMS analysis at IAA is useful to measure 14C-concentration in bioanalysis studies at very low radioactivity level.

  3. 47 CFR 1.30003 - Installations on an AM antenna.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... this chapter). Upon completion of the installation, antenna impedance measurements on the AM antenna... method proof (see § 73.151(c) of this chapter), a base impedance measurement on the tower being modified... impedance measurement shall be retained in the station's records. If the new measured base resistance...

  4. AM(VI) partitioning studies. FY14 final report

    SciTech Connect

    Mincher, Bruce J.

    2014-10-01

    The use of higher oxidation states of americium in partitioning from the lanthanides is under continued investigation by the sigma team. This is based on the hypothesis that Am(VI) can be produced and remain stable in irradiated first cycle raffinate solution long enough to perform solvent extraction for separations. The stability of Am(VI) to autoreduction was measured using millimolar americium concentrations in a 1-cm cell with a Cary 6000 UV/Vis spectrophotometer for data acquisition. At millimolar americium concentrations, Am(VI) is stable enough against its own autoreduction for separations purposes. A second major accomplishment during FY14 was the hot test. Americium oxidation and extraction was performed using a centrifugal contactor-based test bed consisting of an extraction stage and two stripping stages. Sixty-three percent americium extraction was obtained in one extraction stage, in agreement with batch contacts. Promising electrochemical oxidation results have also been obtained, using terpyridine ligand derivatized electrodes for binding of Am(III). Approximately 50 % of the Am(III) was oxidized to Am(V) over the course of 1 hour. It is believed that this is the first demonstration of the electrolytic oxidation of americium in a non-complexing solution. Finally, an initial investigation of Am(VI) extraction using diethylhexylbutyramide (DEHBA) was performed.

  5. AMS/DOE Fellowship Recipients

    SciTech Connect

    Armstrong, Stephanie

    2016-11-21

    The AMS/DOE graduate fellowships were awarded to three students entering their first year of graduate study. The funds allowed each student to take a full course load during their first of year of graduate study which helps each of them to enter the professional, scientific community at an earlier date. Each recipient is academically outstanding, received glowing references of support and demonstrated their strong desire to perform scientific research. As part of the fellowship, each of the students was invited to attend the AMS Annual Meeting where they got to participate in the AMS student conference, attend scientific sessions and visit the exhibition hall. In addition, a student awards luncheon was held where each of the recipients got to meet their sponsor and receive a certificate.

  6. The unusual helium variable AM Canum Venaticorum

    NASA Technical Reports Server (NTRS)

    Provencal, J. L.; Winget, D. E.; Nather, R. E.; Robinson, E. L.; Solheim, J.-E.; Clemens, J. C.; Bradley, J. L.; Kleinman, S. J.; Kanaan, A.; Claver, C. F.

    1995-01-01

    The unusual variable star AM CVn has puzzled astronomers for over 40 years. This object, both a photometric and spectroscopic variable, is believed to contain a pair of hydrogen-deficient white dwarfs of extreme mass ratio, transferring material via an accretion disk. We examine the photometric properties of AM CVn, analyzing 289 hours of high-speed photometric data spanning 1976 to 1992. The power spectrum displays significant peaks at 988.7, 1248.8, 1902.5, 2853.8, 3805.2, 4756.5, and 5707.8 microHz (1011.4, 800.8, 525.6, 350.4, 262.8, 210.2, and 175.2 s). We find no detectable power at 951.3 microHz (1051 s), the previously reported main frequency. The 1902.5, 2853.9, and 3805.2 microHz peaks are multiplets, with frequency splitting in each case of 20.77 +/- 0.05 microHz. The 1902.5 microHz seasonal pulse shapes are identical, within measurement noise, and maintain the same amplitude and phase as a function of color. We have determined the dominant frequency to be 1902.50902 +/- 0.00001 microHz with dot P = +1.71 (+/- 0.04) x 10(exp -11) s/s. We discuss the implications of these findings on a model for AM CVn.

  7. Delineating Glacial Till Bed Kinematics using AMS and Pebble Fabrics

    NASA Astrophysics Data System (ADS)

    Gentoso, M. J.; Evenson, E.; Kodama, K. P.

    2010-12-01

    Anisotropy of magnetic susceptibility (AMS) and pebble fabric analysis was used to explore glacial till bed kinematics in streamlined glacial landforms of the Weedsport Drumlin field of north central New York State. Five wave-truncated drumlins were sampled at two locations each along the shore of Lake Ontario. A total of 500 pebble orientations and 250 AMS samples were collected from 10 sampling sites in the drumlins. Six flutes were also sampled at 10 sampling sites for a total of 500 pebble orientations and 200 AMS measurements. All AMS measurements were conducted on a KLY-3s Kappabridge. The average orientation of the maximum principal susceptibility axes for the drumlins (N2°E) was parallel, within 95% confidence limits, to the average pebble long-axis orientations (N5°W) and parallel to the N-S trend of the drumlins. Both AMS and pebble average orientations plunge toward the north in the “up glacier” direction indicating an imbrication due to ice flow. The clustering of the AMS principal axis directions indicates that the strength of the AMS drumlin fabric is highly variable, at 3 of the 10 sites it is as strong as fabrics developed in a ring shear device (Iverson et al., 2008) at intermediate shear strains. AMS fabrics in the flutes are stronger and more unidirectional than for the drumlins with the average pebble direction (N4°E) parallel to the average AMS maximum susceptibility direction (N12°E), but not at the 95% confidence level. Northward plunge of these average orientations indicates an imbrication. The flutes trend N10°W, so the fabric orientations are not as closely parallel to the glacial landforms for the flutes as they are for the drumlins. Thermal demagnetization of three orthogonal components of an isothermal remanent magnetization indicates that the AMS is carried primarily by maghemite. The stronger AMS fabric in the flutes compared to the drumlins suggests that the till of the flutes has been subjected to higher strains and perhaps

  8. Overview of AMS (CCSDS Asynchronous Message Service)

    NASA Technical Reports Server (NTRS)

    Burleigh, Scott

    2006-01-01

    This viewgraph presentation gives an overview of the Consultative Committee for Space Data Systems (CCSDS) Asynchronous Message Service (AMS). The topics include: 1) Key Features; 2) A single AMS continuum; 3) The AMS Protocol Suite; 4) A multi-continuum venture; 5) Constraining transmissions; 6) Security; 7) Fault Tolerance; 8) Performance of Reference Implementation; 9) AMS vs Multicast (1); 10) AMS vs Multicast (2); 11) RAMS testing exercise; and 12) Results.

  9. Gaia14aae: the First Fully-Eclipsing AM CVn

    NASA Astrophysics Data System (ADS)

    Green, M. J.; Marsh, T. R.; Steeghs, D. T. H.; Breedt, E.; Campbell, H. C.; Dhillon, V. S.; Hardy, L. K.; Littlefair, S. P.

    2017-03-01

    AM CVns are a class of cataclysmic variables consisting of a white dwarf accreting H-deficient matter from a donor star. With periods of 5 to 65 minutes, AM CVns include the shortest period binaries containing white dwarfs. AM CVns are believed to form by one of three formation channels which can in principle be distinguished by the nature of the donor star, but are difficult to constrain observationally. Gaia14aae was one of the first transients discovered by the Gaia Science Alerts project. It eclipses on a period of 50 minutes, and is the only known AM CVn in which the white dwarf is fully eclipsed. This makes it an attractive system for parameter studies. We present an update on our attempts to measure these properties, using high-speed multi-colour photometry. Preliminary results suggest that the donor star is not as degenerate as predicted by models of white dwarf donors.

  10. Texas A&M University

    ERIC Educational Resources Information Center

    Osters, Sandi

    2009-01-01

    Texas A&M University is a research extensive institution located in College Station. More than 45,000 students attend the university (about 20% are graduate or professional students). Academically, the university is known for its engineering, business, and agricultural and veterinary medicine programs, although there are more than 150 programs…

  11. Texas A&M University

    ERIC Educational Resources Information Center

    Osters, Sandi

    2009-01-01

    Texas A&M University is a research extensive institution located in College Station. More than 45,000 students attend the university (about 20% are graduate or professional students). Academically, the university is known for its engineering, business, and agricultural and veterinary medicine programs, although there are more than 150 programs…

  12. I am a White Male

    ERIC Educational Resources Information Center

    Sammons, Jeffrey L.

    1975-01-01

    Suggests that competence and merit are elements in need of examination, and gives four reasons why being a woman, black, or Spanish-American is a qualification for academic appointment. Stresses that energy ought to be directed to increasing support of colleges and universities and not to fighting affirmative action. (Author/AM)

  13. Cannabinoid receptor antagonists AM251 and AM630 activate TRPA1 in sensory neurons

    PubMed Central

    Patil, Mayur; Patwardhan, Amol; Salas, Margaux M.; Hargreaves, Kenneth M.; Akopian, Armen N.

    2011-01-01

    Cannabinoid receptor antagonists have been utilized extensively in vivo as well as in vitro, but their selectivity has not been fully examined. We investigated activation of sensory neurons by two cannabinoid antagonists – AM251 and AM630. AM251 and AM630 activated trigeminal (TG) sensory neurons in a concentration-dependent fashion (threshold 1 μM). AM251 and AM630 responses are mediated by the TRPA1 channel in a majority (90–95%) of small-to-medium TG sensory neurons. AM630 (1–100 μM), but not AM251, was a significantly more potent agonist in cells co-expressing both TRPA1 and TRPV1 channels. We next evaluated AM630 and AM251 effects on TRPV1- and TRPA1-mediated responses in TG neurons. Capsaicin (CAP) effects were inhibited by pre-treatment with AM630, but not AM251. Mustard oil (MO) and WIN55,212-2 (WIN) TRPA1 mediated responses were also inhibited by pre-treatment with AM630, but not AM251 (25uM each). Co-treatment of neurons with WIN and either AM630 or AM251 had opposite effects: AM630 sensitized WIN responses, whereas AM251 inhibited WIN responses. WIN-induced inhibition of CAP responses in sensory neurons was reversed by AM630 pre-treatment and AM251 co-treatment (25μM each), as these conditions inhibit WIN responses. Hindpaw injections of AM630 and AM251 did not produce nocifensive behaviors. However, both compounds modulated CAP-induced thermal hyperalgesia in wild-type mice and rats, but not TRPA1 null-mutant mice. AMs also partially regulate WIN inhibition of CAP-induced thermal hyperalgesia in a TRPA1-dependent fashion. In summary, these findings demonstrate alternative targets for the cannabinoid antagonists, AM251 and AM630, in peripheral antihyperalgesia which involve certain TRP channels. PMID:21645531

  14. Cannabinoid receptor antagonists AM251 and AM630 activate TRPA1 in sensory neurons.

    PubMed

    Patil, Mayur; Patwardhan, Amol; Salas, Margaux M; Hargreaves, Kenneth M; Akopian, Armen N

    2011-09-01

    Cannabinoid receptor antagonists have been utilized extensively in vivo as well as in vitro, but their selectivity has not been fully examined. We investigated activation of sensory neurons by two cannabinoid antagonists - AM251 and AM630. AM251 and AM630 activated trigeminal (TG) sensory neurons in a concentration-dependent fashion (threshold 1 μM). AM251 and AM630 responses are mediated by the TRPA1 channel in a majority (90-95%) of small-to-medium TG sensory neurons. AM630 (1-100 μM), but not AM251, was a significantly more potent agonist in cells co-expressing both TRPA1 and TRPV1 channels. We next evaluated AM630 and AM251 effects on TRPV1- and TRPA1-mediated responses in TG neurons. Capsaicin (CAP) effects were inhibited by pre-treatment with AM630, but not AM251. Mustard oil (MO) and WIN55,212-2 (WIN) TRPA1 mediated responses were also inhibited by pre-treatment with AM630, but not AM251 (25 uM each). Co-treatment of neurons with WIN and either AM630 or AM251 had opposite effects: AM630 sensitized WIN responses, whereas AM251 inhibited WIN responses. WIN-induced inhibition of CAP responses in sensory neurons was reversed by AM630 pre-treatment and AM251 co-treatment (25 μM each), as these conditions inhibit WIN responses. Hindpaw injections of AM630 and AM251 did not produce nocifensive behaviors. However, both compounds modulated CAP-induced thermal hyperalgesia in wild-type mice and rats, but not TRPA1 null-mutant mice. AMs also partially regulate WIN inhibition of CAP-induced thermal hyperalgesia in a TRPA1-dependent fashion. In summary, these findings demonstrate alternative targets for the cannabinoid antagonists, AM251 and AM630, in peripheral antihyperalgesia which involve certain TRP channels.

  15. Performances of the AMS-02 Electromagnetic Calorimeter

    NASA Astrophysics Data System (ADS)

    Adloff, C.; Coignet, G.; Girard, L.; Goy, C.; Kossakowski, R.; Lees-Rosier, S.; Pochon, J.; Vialle, J. P.; Cervelli, F.; di Falco, S.; Galeotti, S.; Incagli, M.; Pedreschi, E.; Spinella, F.; Venanzoni, G.; Falchini, E.; Maestro, P.; Marrocchesi, P. S.; Paoletti, R.; Pilo, F.; Turini, N.; Valle, G.; Bolmont, J.; Jacholkowska, A.; Piron, F.; Sapinski, M.; Chen, G.; Chen, G.; Chen, H. S.; Lu, Y.; Yang, C.

    2004-07-01

    A 3D imaging electromagnetic calorimeter (ECAL) made of scintillating fibers embedded in lead has been developed for the AMS-02 experiment to be installed on the International Space Station. A full scale ECAL prototype, partially instrumented, was tested in July 2002 in a beam at CERN. Several million events were recorded using muon, electron, proton, and antiproton beams, from which the ECAL behavior was determined. Results on the measurement of the ECAL parameters and performances are presented : radiation length, linearity, energy and angular resolutions, e/p separation.

  16. AMS of the Minor Plutonium Isotopes

    PubMed Central

    Steier, P.; Hrnecek, E.; Priller, A.; Quinto, F.; Srncik, M.; Wallner, A.; Wallner, G.; Winkler, S.

    2013-01-01

    VERA, the Vienna Environmental Research Accelerator, is especially equipped for the measurement of actinides, and performs a growing number of measurements on environmental samples. While AMS is not the optimum method for each particular plutonium isotope, the possibility to measure 239Pu, 240Pu, 241Pu, 242Pu and 244Pu on the same AMS sputter target is a great simplification. We have obtained a first result on the global fallout value of 244Pu/239Pu = (5.7 ± 1.0) × 10−5 based on soil samples from Salzburg prefecture, Austria. Furthermore, we suggest using the 242Pu/240Pu ratio as an estimate of the initial 241Pu/239Pu ratio, which allows dating of the time of irradiation based solely on Pu isotopes. We have checked the validity of this estimate using literature data, simulations, and environmental samples from soil from the Salzburg prefecture (Austria), from the shut down Garigliano Nuclear Power Plant (Sessa Aurunca, Italy) and from the Irish Sea near the Sellafield nuclear facility. The maximum deviation of the estimated dates from the expected ages is 6 years, while relative dating of material from the same source seems to be possible with a precision of less than 2 years. Additional information carried by the minor plutonium isotopes may allow further improvements of the precision of the method. PMID:23565016

  17. AMS of the Minor Plutonium Isotopes.

    PubMed

    Steier, P; Hrnecek, E; Priller, A; Quinto, F; Srncik, M; Wallner, A; Wallner, G; Winkler, S

    2013-01-01

    VERA, the Vienna Environmental Research Accelerator, is especially equipped for the measurement of actinides, and performs a growing number of measurements on environmental samples. While AMS is not the optimum method for each particular plutonium isotope, the possibility to measure (239)Pu, (240)Pu, (241)Pu, (242)Pu and (244)Pu on the same AMS sputter target is a great simplification. We have obtained a first result on the global fallout value of (244)Pu/(239)Pu = (5.7 ± 1.0) × 10(-5) based on soil samples from Salzburg prefecture, Austria. Furthermore, we suggest using the (242)Pu/(240)Pu ratio as an estimate of the initial (241)Pu/(239)Pu ratio, which allows dating of the time of irradiation based solely on Pu isotopes. We have checked the validity of this estimate using literature data, simulations, and environmental samples from soil from the Salzburg prefecture (Austria), from the shut down Garigliano Nuclear Power Plant (Sessa Aurunca, Italy) and from the Irish Sea near the Sellafield nuclear facility. The maximum deviation of the estimated dates from the expected ages is 6 years, while relative dating of material from the same source seems to be possible with a precision of less than 2 years. Additional information carried by the minor plutonium isotopes may allow further improvements of the precision of the method.

  18. Pinpointing cosmic ray propagation with the AMS-02 experiment

    SciTech Connect

    Pato, Miguel; Hooper, Dan; Simet, Melanie E-mail: dhooper@fnal.gov

    2010-06-01

    The Alpha Magnetic Spectrometer (AMS-02), which is scheduled to be deployed onboard the International Space Station later this year, will be capable of measuring the composition and spectra of GeV-TeV cosmic rays with unprecedented precision. In this paper, we study how the projected measurements from AMS-02 of stable secondary-to-primary and unstable ratios (such as boron-to-carbon and beryllium-10-to-beryllium-9) can constrain the models used to describe the propagation of cosmic rays throughout the Milky Way. We find that within the context of fairly simple propagation models, all of the model parameters can be determined with high precision from the projected AMS-02 data. Such measurements are less constraining in more complex scenarios, however, which allow for departures from a power-law form for the diffusion coefficient, for example, or for inhomogeneity or stochasticity in the distribution and chemical abundances of cosmic ray sources.

  19. 7 CFR 65.105 - AMS.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) REGULATIONS AND STANDARDS UNDER THE AGRICULTURAL..., AND GINSENG General Provisions Definitions § 65.105 AMS. AMS means the Agricultural Marketing...

  20. Am(VI) Extraction Final Report: FY16

    SciTech Connect

    Mincher, Bruce Jay; Grimes, Travis Shane; Tillotson, Richard Dean; Law, Jack Douglas

    2016-08-01

    This report summarizes activities related to hexavalent Am extraction for FY16, in completion of FCR&D Milestone M3FT-16IN030103027. Activities concentrated on three areas of research: 1) centrifugal contactor hot testing, 2) Am(VI) stability studies, and 3) alternative oxidant studies. A brief summary of each task follows. Hot Testing: A new engineering-scale oxidation and solvent extraction test bed was built at Idaho National Laboratory to allow for solvent extraction testing of minor actinide separation concepts. The test bed consists of an oxidation vessel, filtration apparatus, four, 3D printed, 2-cm diameter centrifugal contactors, feed/product vessels, and sample ports. This system replaced the previous 3 stage, 5-cm contactor test bed that was used for the initial testing in FY14. In the FY16 hot test, a feed simulant was spiked with 243Am and 139Ce and treated with 60 g/L sodium bismuthate for two hours to oxidize the Am(III) to Am(VI). This solution was then pumped through a filter and into the four-stage centrifugal contactor setup. The organic phase solvent formulation was 1 M diethylhexylbutyramide (DEHBA)/dodecane. The test showed that Am(VI) was produced by bismuthate oxidation and the residual oxidant was successfully filtered without back pressure buildup. Sixty-four percent of Am was extracted in the contactors using DEHBA. Both Am and Ce were quantitatively stripped by 0.1 M H2O2. Successful demonstration of the utility of small, printable contactors suggests that hot testing of separations concepts can now be conducted more often, since it is cheaper, generates less waste, and entails much less radcon risk than previous testing. Am(VI) stability: A rigorous examination of reagents was conducted to determine if contaminants could interfere with Am oxidation and extraction. An series of DAm measurements showed that bismuthate particle size, water source, acid quality, and DAAP batch or pre-treatment had little effect on extraction efficiency

  1. Content-Based Networking: DTN, AMS, Sharednet

    NASA Technical Reports Server (NTRS)

    Burleigh, Scott

    2006-01-01

    A detailed viewgraph presentation on DTN, AMS, and Sharednet content-based networking is shown. The contents include: 1) DARPA Content-Based Networking Summary of Requirements; 2) Concept; 3) Key Features of AMS; 4) Overview of Sharednet; 5) SharedNet Deployment History; 6) SharedNet AMS DTN; 7) Detailed Structure; and 8) Bottom line.

  2. Selection of Additive Manufacturing (AM) Equipment

    DTIC Science & Technology

    2017-04-01

    Recent advancements in technology have enabled Additive Manufacturing (AM), also known as Three-Dimensional (3-D) printing, to become a powerful ...Aviation and Missile Research, Development, and Engineering Center (AMRDEC) has been tracking AM over recent years and is considering investing in...9 1 I. INTRODUCTION Additive Manufacturing (AM) has become a very powerful

  3. 7 CFR 1280.602 - Administrator, AMS.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 10 2010-01-01 2010-01-01 false Administrator, AMS. 1280.602 Section 1280.602... INFORMATION ORDER Procedures To Request a Referendum Definitions § 1280.602 Administrator, AMS. Administrator, AMS, means the Administrator of the Agricultural Marketing Service, or any officer or employee of...

  4. 7 CFR 1230.602 - Administrator, AMS.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 10 2010-01-01 2010-01-01 false Administrator, AMS. 1230.602 Section 1230.602... CONSUMER INFORMATION Procedures for the Conduct of Referendum Definitions § 1230.602 Administrator, AMS. The term Administrator, AMS, means the Administrator of the Agricultural Marketing Service, or...

  5. Dosimetry studies on prototype 241Am sources for brachytherapy.

    PubMed

    Nath, R; Gray, L

    1987-06-01

    Sealed sources of 241Am emit primarily 60 keV photons which, because of multiple Compton scattering, produce dose distributions in water that are comparable to those from 226Ra or 137Cs. However, americium gamma rays can be shielded by thin layers of high atomic number materials since the half value layer thickness is only 1/8th of a mm of lead for americium gamma rays as compared to a value of 12 mm for 226Ra gamma rays. This may allow effective in vivo shielding of critical organs, for example; the bladder can be partially shielded by hypaque solution, and the rectum and sigmoid colon by barium sulfate. In addition, the exposure to medical personnel involved in intracavitary application and patient care may be reduced substantially by the use of relatively thin lead aprons and light weight, portable shields. To investigate the feasibility of 241Am sources for intracavitary irradiation, dosimetry studies on prototype 241Am sources have been performed and a computer model for the determination of dose distributions around encapsulated cylindrical sources of 241Am has been developed and tested. Results of dosimetry measurements using ionization chambers, lithium fluoride thermoluminescent dosimeters, a scanning scintillation probe, and film dosimetry, confirm theoretical predictions that these sources can deliver dose rates adequate for intracavitary irradiation. Further dosimetry measurements in simulated clinical situations using lead foils and test tubes filled with hypaque or barium sulfate, confirm the predicted effectiveness of in vivo shielding which can be readily achieved with 241Am sources.

  6. Antiproton identification below threshold with the AMS-02 RICH detector

    NASA Astrophysics Data System (ADS)

    Li, Zi-Yuan; Delgado Mendez, Carlos Jose; Giovacchini, Francesca; Haino, Sadakazu; Hoffman, Julia

    2017-05-01

    The Alpha Magnetic Spectrometer (AMS-02), which is installed on the International Space Station (ISS), has been collecting data successfully since May 2011. The main goals of AMS-02 are the search for cosmic anti-matter, dark matter and the precise measurement of the relative abundance of elements and isotopes in galactic cosmic rays. In order to identify particle properties, AMS-02 includes several specialized sub-detectors. Among these, the AMS-02 Ring Imaging Cherenkov detector (RICH) is designed to provide a very precise measurement of the velocity and electric charge of particles. We describe a method to reject the dominant electron background in antiproton identification with the use of the AMS-02 RICH detector as a veto for rigidities below 3 GV. A ray tracing integration method is used to maximize the statistics of p¯ with the lowest possible e- background, providing 4 times rejection power gain for e- background with respect to only 3% of p¯ signal efficiency loss. By using the collected cosmic-ray data, e- contamination can be well suppressed within 3% with β ≈ 1, while keeping 76% efficiency for p¯ below the threshold. Supported by China Scholarship Council (CSC) under Grant No.201306380027.

  7. Biological AMS at Uppsala University: Status report

    NASA Astrophysics Data System (ADS)

    Salehpour, Mehran; Forsgard, Niklas; Possnert, Göran

    2010-04-01

    In January 2007 a new research program was initiated at Uppsala University focusing on the biological applications of AMS. We have used a 5 MV Pelletron Tandem accelerator to study biological samples. With Microdosing applications in mind, a variety of measurements have been performed on human blood, plasma and urine that have been labeled with a 14C-labeled pharmaceutical drug covering a concentration range, spanning 3 orders of magnitude. Furthermore, by studying small sample amounts and low concentrations, we have demonstrated sensitivity in the hundred zeptomole range for a small pharmaceutical substance in human blood. Another application of interest, based on the enhanced 14C activity from the cold war bomb-peak, is dating of DNA molecules providing fundamental data for the regenerative medicine and stem cell research community. We show data on a sensitive carrier method for measuring the isotopic ratio of small biological sample in the few μgC range.

  8. Internal gastargets in AmPS

    NASA Astrophysics Data System (ADS)

    Kaan, A. P.; Postma, O.; van den Brand, J. F. J.; van Leeuwen, E.; Doets, M.; Kraan, M.

    1997-05-01

    Internal gas targets in AmPS A.P. Kaan, O. Postma, J.F.J. van den Brand, E. van Leeuwen, M. Doets, M. Kra= an National Institute for Nuclear Physics and High Energy Physics; Kruislaan 409; 1098 SJ Amsterdam; Holland In the Amsterdam Puls Stretcher/storage ring AmPS(1 GeV electrons), we designed a set-up in order to accommodate a gas target with a density of 1016 mol/cm2. The storage cell needed for this purpose is a aluminium tube with a length of 40 cm, a diameter of 15 mm and a wall thickness of 25 =B5m. Three sets of conductance limiters on both sides of the target, combined with dry turbopumps are designed to be used as differential pumping stations. These limiters cause discontinuities in the beam path and must therefor be retractable and radio frequency compatible in both positions. Low =B5 materials must be used because of the depolarisation effects of changing magnetic fields. The calculations show that the flow resistance's are sufficient to reduce the load of the getter pumps to a level with which the lifetime of the pump elements remain acceptable. The design of the mechanics and the vacuum system will be explained. Recent results from the measurements after installation in combination with the influence on the lifetime on the beam will be presented

  9. Urinary amylase / urinary creatinine ratio (uAm/uCr) - a less-invasive parameter for management of hyperamylasemia

    PubMed Central

    2013-01-01

    Background The serum level of amylase (sAm) is commonly used as a biochemical marker for diagnosis and management of pancreatic disorders. However, the use of the urine level of amylase (uAm) is limited in practice, because the diagnostic ability of uAm is inferior to that of sAm. In the present study, the possible concordance of uAm-rerated parameters with sAm was investigated, and evaluate the usefulness of uAm for management of hyperamylasemia. Methods From June 1995 to October 2009, 804 samples of both urine and blood were collected from 128 patients in order to measure the serum level of amylase (sAm) and the urine level of amylase (uAm) and creatinine (uCr). Concordance of parameters using uAm compared to sAm was assessed. Parameters used were uAm, amylase creatinine clearance ratio (ACCR), and the ratio of uAm to uCr (uAm/uCr). Results uAm/uCr had the best correlation with sAm (r = 0.779, p < 0.001) compared to uAm (r = 0.620, p < 0.001) and to ACCR (r = 0.374, p < 0.001), when sAm was over the standard level. The area under the receiver operating characteristic curve of uAm/uCr (0.884) was significantly higher than that of uAm (0.766) and of ACCR (0.666) (p < 0.001 for each). The cutoff value of uAm/uCr was 569.8, with a sensitivity of 81.0% and a specificity of 83.1%. Conclusions The uAm/uCr ratio correlated with sAm, and may be an alternative to sAm for prediction of hyperamylasemia. Use of urine samples results in a decreased need for blood sampling, which is especially beneficial in pediatric patients. PMID:24330759

  10. The Basis for Developing Samarium AMS for Fuel Cycle Analysis

    SciTech Connect

    Buchholz, B A; Biegalski, S R; Whitney, S M; Tumey, S J; Weaver, C J

    2008-10-13

    Modeling of nuclear reactor fuel burnup indicates that the production of samarium isotopes can vary significantly with reactor type and fuel cycle. The isotopic concentrations of {sup 146}Sm, {sup 149}Sm, and {sup 151}Sm are potential signatures of fuel reprocessing, if analytical techniques can overcome the inherent challenges of lanthanide chemistry, isobaric interferences, and mass/charge interferences. We review the current limitations in measurement of the target samarium isotopes and describe potential approaches for developing Sm-AMS. AMS sample form and preparation chemistry will be discussed as well as possible spectrometer operating conditions.

  11. AMS in payload bay viewed from Mir Space Station

    NASA Image and Video Library

    2016-08-24

    STS091-367-033 (2-12 June 1998) --- This photo of the Space Shuttle Discovery's aft section features the Alpha Magnetic Spectrometer (AMS), as seen from Russia's Mir space station, docked with Discovery at the time. AMS is the first large-magnet experiment ever placed in Earth orbit. The scientific goal of this high-energy physics experiment is to increase our understanding of the composition and origin of the universe. It is designed to search for and measure charged particles, including antimatter, outside Earth's atmosphere. The charge of such particles can be identified only by their trajectories in a magnetic field.

  12. Status report on the Seoul National University AMS facility

    NASA Astrophysics Data System (ADS)

    Kim, J. C.; Youn, M.; Kim, I. C.; Park, J. H.; Song, Y. M.; Kang, J.; Choi, H. R.

    2004-08-01

    We report recent progress at the Seoul National University AMS facility in the area of sample preparations, facility maintenance, and briefly describe examples of present applications and future plans. The background level depending on the preparation methods is discussed, and water preparation line that are still under development is described. As the successful application of our facility, dating results of a historic site and a Paleolithic site, dating of Siberian permafrost and bomb pulse measurement are shown. Future plans for Be/Al AMS and biomedical application are discussed.

  13. Electronic and magnetic properties of Am and Cm

    SciTech Connect

    Edelstein, N.

    1985-02-01

    A review of the present status of the analyses of the optical spectra of Am and Cm in various oxidation states is given. From these analyses, the magnetic properties of the ground states of these ions can be determined. These predicted values are compared with the various magnetic measurements available.

  14. Design and Qualification of the AMS-02 Flight Cryocoolers

    NASA Technical Reports Server (NTRS)

    Shirey, Kimberly; Banks,Stuart; Boyle, Rob; Unger, Reuven

    2005-01-01

    Four commercial Sunpower M87N Stirling-cycle cryocoolers will be used to extend the lifetime of the Alpha Magnetic Spectrometer-02 (AMS-02) experiment. The cryocoolers will be mounted to the AMS-02 vacuum case using a structure that will thermally and mechanically decouple the cryocooler from the vacuum case. This paper discusses modifications of the Sunpower M87N cryocooler to make it acceptable for space flight applications and suitable for use on AMS-02. Details of the flight model qualification test program are presented. AMS-02 is a state-of-the-art particle physics detector containing a large superfluid helium-cooled superconducting magnet. Highly sensitive detector plates inside the magnet measure a particle's speed, mass, charge, and direction. The AMS-02 experiment, which will be flown as an attached payload on the International Space Station, will study the properties and origin of cosmic particles and nuclei including antimatter and dark matter. Two engineering model cryocoolers have been under test at NASA Goddard since November 2001. Qualification testing of the engineering model cryocooler bracket assembly including random vibration and thermal vacuum testing was completed at the end of April 2005. The flight cryocoolers were received in December 2003. Acceptance testing of the flight cryocooler bracket assemblies began in May 2005 .

  15. Space Flight Qualification Program for the AMS-2 Commercial Cryocoolers

    NASA Technical Reports Server (NTRS)

    Shirey, K. A.; Banks, I. S.; Breon, S. R.; Boyle, R. F.; Krebs, Carolyn A. (Technical Monitor)

    2002-01-01

    The Alpha Magnetic Spectrometer-02 (AMS-02) experiment is a state-of-the-art particle physics detector containing a large superfluid helium-cooled superconducting magnet. Highly sensitive detector plates inside the magnet measure a particle's speed, momentum, charge, and path. The AMS-02 experiment will study the properties and origin of cosmic particles and nuclei including antimatter and dark matter. AMS-02 will be installed on the International Space Station on Utilization Flight-4. The experiment will be run for at least three years. To extend the life of the stored cryogen and minimize temperature gradients around the magnet, four Stirling-cycle Sunpower M87N cryocoolers will be integrated with AMS-02. The cryocooler cold tip will be connected via a flexible strap to the outer vapor cooled shield of the dewar. Initial thermal analysis shows the lifetime of the experiment is increased by a factor of 2.8 with the use of the cryocooler. The AMS-02 project selected the Sunpower M87 cryocoolers and has asked NASA Goddard to qualify the cryocoolers for space flight use. This paper describes the interfaces with the cryocoolers and presents data collected during testing of the two engineering model cryocoolers. Tests include thermal performance characterization and launch vibration testing. Magnetic field compatibility testing will be presented in a separate paper at the conference.

  16. Design and Qualification of the AMS-02 Flight Cryocoolers

    NASA Technical Reports Server (NTRS)

    Shirey, Kimberly; Banks,Stuart; Boyle, Rob; Unger, Reuven

    2005-01-01

    Four commercial Sunpower M87N Stirling-cycle cryocoolers will be used to extend the lifetime of the Alpha Magnetic Spectrometer-02 (AMS-02) experiment. The cryocoolers will be mounted to the AMS-02 vacuum case using a structure that will thermally and mechanically decouple the cryocooler from the vacuum case. This paper discusses modifications of the Sunpower M87N cryocooler to make it acceptable for space flight applications and suitable for use on AMS-02. Details of the flight model qualification test program are presented. AMS-02 is a state-of-the-art particle physics detector containing a large superfluid helium-cooled superconducting magnet. Highly sensitive detector plates inside the magnet measure a particle's speed, mass, charge, and direction. The AMS-02 experiment, which will be flown as an attached payload on the International Space Station, will study the properties and origin of cosmic particles and nuclei including antimatter and dark matter. Two engineering model cryocoolers have been under test at NASA Goddard since November 2001. Qualification testing of the engineering model cryocooler bracket assembly including random vibration and thermal vacuum testing was completed at the end of April 2005. The flight cryocoolers were received in December 2003. Acceptance testing of the flight cryocooler bracket assemblies began in May 2005 .

  17. Low energy AMS of americium and curium

    NASA Astrophysics Data System (ADS)

    Christl, Marcus; Dai, Xiongxin; Lachner, Johannes; Kramer-Tremblay, Sheila; Synal, Hans-Arno

    2014-07-01

    Accelerator mass spectrometry (AMS) has evolved over the past years as one of the most sensitive, selective, and robust techniques for actinide analyses. While analyses of U and Pu isotopes have already become routine at the ETH Zurich 0.5 MV AMS system "Tandy", there is an increasing demand for highly sensitive analyses of the higher actinides such as Am and Cm for bioassay applications and beyond. In order to extend the actinide capabilities of the compact ETH Zurich AMS system and to develop new, more sensitive bioassay routines, a pilot study was carried out. The aim was to investigate and document the performance and the potential background of Am and Cm analyses with low energy AMS. Our results show that 241Am and Cm isotopes can be determined relative to a 243Am tracer if samples and AMS standards are prepared identically with regard to the matrix elements, in which the sample is dispersed. In this first test, detection limits for Cm and Am isotopes are all in the sub-femtogram range and even below 100 ag for Cm isotopes. In a systematic background study in the mass range of the Cm isotopes, two formerly unknown metastable triply charged Th molecules were found on amu(244) and amu(248). The presence of such a background is not a principal problem for AMS if the stripper pressure is increased accordingly. Based on our first results, we conclude that ultra-trace analyses of Am and Cm isotopes for bioassay are very well possible with low energy AMS.

  18. The AMS-02 lead-scintillating fibres Electromagnetic Calorimeter

    NASA Astrophysics Data System (ADS)

    Adloff, C.; Basara, L.; Bigongiari, G.; Bosi, F.; Brun, P.; Cadoux, F.; Cervelli, F.; Chambert, V.; Chen, G.; Chen, G. M.; Chen, H. S.; Coignet, G.; Cougoulat, G.; Di Falco, S.; Dubois, J. M.; Elles, S.; Falchini, E.; Fiasson, A.; Fougeron, D.; Fouque, N.; Galeotti, S.; Gallucci, G.; Gherarducci, F.; Girard, L.; Giuseppe, F.; Goy, C.; Hermel, R.; Incagli, M.; Jacquemier, J.; Journet, L.; Kossakowski, R.; Lepareur, V.; Li, Z. H.; Lieunard, B.; Lomtadze, T.; Lu, Y. S.; Maestro, P.; Magazzù, C.; Maire, M.; Orsini, A.; Paniccia, M.; Pedreschi, E.; Peltier, F.; Piendibene, M.; Pilo, F.; Pochon, J.; Rambure, T.; Rosier-Lees, S.; Spinella, F.; Tang, X. W.; Tassan-Viol, J.; Tazzioli, A.; Vannini, C.; Vialle, J. P.; Zhuang, H. L.

    2013-06-01

    The Electromagnetic Calorimeter (ECAL) of the AMS-02 experiment is a fine grained lead-scintillating fibres sampling calorimeter that allows for a precise three-dimensional imaging of the longitudinal and lateral shower development. It provides a high (≥106) electron/hadron discrimination with the other AMS-02 detectors [1] and good energy resolution. The calorimeter also provides a standalone photon trigger capability to AMS-02. The mechanical assembly was realized to ensure minimum weight, still supporting the intrinsically heavy calorimeter during launch. ECAL light collection system and electronics are designed to measure electromagnetic particles over a wide energy range, from GeV up to TeV. A full-scale flight-like model was tested using electrons and proton beams with energies ranging from 6 to 250 GeV.

  19. The ANTARES AMS facility at ANSTO

    NASA Astrophysics Data System (ADS)

    Fink, D.; Hotchkis, M.; Hua, Q.; Jacobsen, G.; Smith, A. M.; Zoppi, U.; Child, D.; Mifsud, C.; van der Gaast, H.; Williams, A.; Williams, M.

    2004-08-01

    This paper presents an overview of ANTARES operations, describing (1) technical upgrades that now allow routine 0.3-0.4% 14C precision for 1 mg carbon samples and 1% precision for 100 micrograms, (2) proficiency at 236U measurements in environmental samples, (3) new developments in AMS of platinum group elements and (4), some major application projects undertaken over the period of the past three years. Importantly, the facility is poised to enter into a new phase of expansion with the recent delivery of a 2 MV 14C tandem accelerator system from High Voltage Engineering (HVE) and a stable isotope ratio mass spectrometer from Micromass Inc. for combustion of organic samples and isotopic analysis.

  20. Neutron transmission and capture of 241Am

    NASA Astrophysics Data System (ADS)

    Lampoudis, C.; Kopecky, S.; Plompen, A.; Schillebeeckx, P.; Wynants, R.; Gunsing, F.; Sage, C.; Bouland, O.; Noguere, G.

    2013-03-01

    A set of neutron transmission and capture experiments based on the Time Of Flight (TOF) technique, were performed in order to determine the 241Am capture cross section in the energy range from 0.01 eV to 1 keV. The GELINA facility of the Institute for Reference Materials and Measurements (IRMM) served as the neutron source. A pair of C6D6 liquid scintillators was used to register the prompt gamma rays emerging from the americium sample, while a Li-glass detector was used in the transmission setup. Results from the capture and transmission data acquired are consistent with each other, but appear to be inconsistent with the evaluated data files. Resonance parameters have been derived for the data up to the energy of 100 eV.

  1. AM-AM/AM-PM distortion versus complex Volterra kernels for modeling RF transceiver blocks

    NASA Astrophysics Data System (ADS)

    Cimmino, Rosario F.; Monsurrò, Pietro; Romano, Francesco; Scotti, Giuseppe; Trifiletti, Alessandro

    2016-07-01

    We investigate AM/PM distortion models and compare them with baseband (BB) Volterra models. We show that the AM/PM model can be considered a special case of memoryless baseband Volterra models, and that adding memory can improve modeling accuracy by allowing the simulation of more complex nonlinearities. We report models of an LNA, a downconversion mixer, an upconversion mixer, and one class-AB Power Amplifier. All circuits are simulated using the 45nm STMicroelectronics CMOS process with Virtuoso, while the PA, with discrete devices, is simulated using ADS. Adding memory improves performance at the expense of increased numerical complexity: this makes real-time simulation and real-time calibration more expensive, so that there is a trade-off between complexity and accuracy or linearity (after calibration). Foreground calibration's techniques only require the real-time computation of the correction (inverse) system's output, whereas background calibration also requires the real-time estimation of the model coefficients, so the relevant complexity is that which is required during correction.

  2. Correlation of PET and AMS analyses for early kinetics of 2-fluoro-2-deoxyglucose (FDG)

    NASA Astrophysics Data System (ADS)

    Minamimoto, Ryogo; Hamabe, Yoshimi; Miyaoka, Teiji; Theeraladanon, Chumpol; Oka, Takashi; Matsui, Takao; Inoue, Tomio

    2010-04-01

    The draft of the guidelines for microdosing in clinical trials was published in Japan in 2008 following the guidelines of the European Medicines Agency (EMEA) and the Food and Drug Administration (FDA). It recommends utilizing accelerator mass spectrometry (AMS), liquid chromatography/mass spectrometry (LC/MS/MS), and positron emission tomography (PET) for monitoring drug metabolites in preclinical studies. In this study, we clarified the correlation in measuring result between PET and AMS. The AMS measurement was undergone by using AMS system of Institute of Accelerator Analysis Ltd. (IAA, Kawasaki, Japan). First the back ground 14C level of blood in mice was measured by AMS. Second, we clarified the relationship between AMS and PET by using 2-fluoro-2-deoxyglucose (FDG). The correlation coefficient ( r) of the measurements using PET ( 18F-FDG) and AMS ( 14C-FDG) were quite high at 0.97 ( Y = 7.54 E - 05 X + 0.02, p < 0.001). The blood clearance profile of 18F-FDG was nearly identical with that of 14C-FDG. These results indicate that the AMS analysis has excellent correlation with the PET method.

  3. 33 CFR 103.505 - Elements of the Area Maritime Security (AMS) Plan.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Elements of the Area Maritime...) Plan § 103.505 Elements of the Area Maritime Security (AMS) Plan. The AMS Plan should address the following elements, as applicable: (a) Details of both operational and physical measures that are in place...

  4. Mechanical reliability of AMS hydraulic penile prostheses.

    PubMed

    Kim, S C

    1995-12-01

    The mechanical reliability of AMS hydraulic penile prostheses implanted in 203 patients from April 1985 to June 1995 were evaluated. AMS Hydroflex prosthesis showed the highest incidence of mechanical failure (18.8%; 6/32 patients) during a mean follow-up period of 94.5 (64-117) months. Mean functioning time of the prostheses until malfunction was 50 (0-100) months. Bilateral fractures at junction of rear reservior and inflation chamber were found in 3 patients. AMS Dynaflex had a failure rate of 2.4% (2/85 patients) for an average of 35.3 (1-59) months. One patient showed complete fracture of silicone ball covering the proximal end of rear reservior onto which rear tip extenders are snapped. Regarding 3-piece inflatable prosthesis, AMS 700, AMS 700CX and AMS Ultrex had failure rates of 11.1% (1/9 patients), 10.5% (2/19 patients) and 4.0% (1/25 patients) during a mean follow-up period of 116.4 (103-125), 79.0 (60-94) and 44.4 (22-57) months, respectively. The verified causes of the mechanical failures were a tiny rupture of the cylinder in one case of AMS 700, an incomplete fracture of input tube in one case of AMS 700CX and a pump malfunction in one case of Ultrex. However, none of 33 cases of AMS 700CXM showed mechanical failure for an average of 21.3 (2-43) months. Therefore, AMS 700CXM and Ultrex seem to be very reliable, and the reliability of AMS Dynaflex was much higher than that of AMS Hydroflex. However, the long-term reliability of these devices needs more time to be determined.

  5. Mechanical reliability of AMS hydraulic penile prostheses.

    PubMed Central

    Kim, S. C.

    1995-01-01

    The mechanical reliability of AMS hydraulic penile prostheses implanted in 203 patients from April 1985 to June 1995 were evaluated. AMS Hydroflex prosthesis showed the highest incidence of mechanical failure (18.8%; 6/32 patients) during a mean follow-up period of 94.5 (64-117) months. Mean functioning time of the prostheses until malfunction was 50 (0-100) months. Bilateral fractures at junction of rear reservior and inflation chamber were found in 3 patients. AMS Dynaflex had a failure rate of 2.4% (2/85 patients) for an average of 35.3 (1-59) months. One patient showed complete fracture of silicone ball covering the proximal end of rear reservior onto which rear tip extenders are snapped. Regarding 3-piece inflatable prosthesis, AMS 700, AMS 700CX and AMS Ultrex had failure rates of 11.1% (1/9 patients), 10.5% (2/19 patients) and 4.0% (1/25 patients) during a mean follow-up period of 116.4 (103-125), 79.0 (60-94) and 44.4 (22-57) months, respectively. The verified causes of the mechanical failures were a tiny rupture of the cylinder in one case of AMS 700, an incomplete fracture of input tube in one case of AMS 700CX and a pump malfunction in one case of Ultrex. However, none of 33 cases of AMS 700CXM showed mechanical failure for an average of 21.3 (2-43) months. Therefore, AMS 700CXM and Ultrex seem to be very reliable, and the reliability of AMS Dynaflex was much higher than that of AMS Hydroflex. However, the long-term reliability of these devices needs more time to be determined. PMID:8924226

  6. Liquid chromatography - tandem quadrupole mass spectrometry and comprehensive two-dimensional gas chromatography - time-of-flight mass spectrometry measurement of targeted metabolites of Methylobacterium extorquens AM1 grown on two different carbon sources

    PubMed Central

    Yang, Song; Sadilek, Martin; Synovec, Robert E.; Lidstrom, Mary E.

    2009-01-01

    Complementary methods using liquid chromatography - tandem quadrupole mass spectrometry (LC-MS/MS) and comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GC × GC-TOF-MS) were developed and applied to determine targeted metabolites involved in central carbon metabolism [including tricarboxylic acid cycle, serine cycle, ethylmalonyl-coenzyme A (ethylmalonyl-CoA) pathway and poly-β-hydroxybutyrate cycle] of the bacterium Methylobacterium extorquens AM1 grown on two carbon sources, ethylamine (C2) and succinate (C4). Nucleotides, acyl-CoAs and a few volatile metabolites in cell extracts of M. extorquens AM1 were readily separated using either hydrophilic interaction liquid chromatography or reversed-phase liquid chromatography, and detected with good sensitivity by MS/MS. However, volatile intermediates within a low mass range (<300 m/z), especially at low abundance (such as glyoxylic acid and others <500 nM), were more effectively analyzed by GC × GC-TOF-MS which often provided better sensitivity, resolution and reproducibility. The complementary nature of the LC-based and GC-based methods allowed the comparison of 39 metabolite concentrations (the lowest level was at 139.3 nM). The overlap between the LC and GC-based methods of 7 metabolites provided a basis to check for consistency between the two methods, and thus provided some validation of the quantification accuracy. The abundance change of 20 intermediates further suggested differences in pathways linked to C2 and C4 metabolism. PMID:19268957

  7. Neutron capture cross section of Am241

    NASA Astrophysics Data System (ADS)

    Jandel, M.; Bredeweg, T. A.; Bond, E. M.; Chadwick, M. B.; Clement, R. R.; Couture, A.; O'Donnell, J. M.; Haight, R. C.; Kawano, T.; Reifarth, R.; Rundberg, R. S.; Ullmann, J. L.; Vieira, D. J.; Wilhelmy, J. B.; Wouters, J. M.; Agvaanluvsan, U.; Parker, W. E.; Wu, C. Y.; Becker, J. A.

    2008-09-01

    The neutron capture cross section of Am241 for incident neutrons from 0.02 eV to 320 keV has been measured with the detector for advanced neutron capture experiments (DANCE) at the Los Alamos Neutron Science Center. The thermal neutron capture cross section was determined to be 665±33 b. Our result is in good agreement with other recent measurements. Resonance parameters for En<12 eV were obtained using an R-matrix fit to the measured cross section. The results are compared with values from the ENDF/B-VII.0, Mughabghab, JENDL-3.3, and JEFF-3.1 evaluations. Γn neutron widths for the first three resonances are systematically larger by 5-15% than the ENDF/B-VII.0 values. The resonance integral above 0.5 eV was determined to be 1553±7 b. Cross sections in the resolved and unresolved energy regions above 12 eV were calculated using the Hauser-Feshbach theory incorporating the width-fluctuation correction of Moldauer. The calculated results agree well with the measured data, and the extracted averaged resonance parameters in the unresolved resonance region are consistent with those for the resolved resonances.

  8. Characterisation of a protection level Am-241 calibration source

    NASA Astrophysics Data System (ADS)

    Bass, G. A.; Rossiter, M. J.; Williams, T. T.

    1992-11-01

    The various measurements involved in the commissioning process of an Am-241 radioactive source and transport mechanisms to be used for protection level calibration work are detailed. The source and its handling mechanisms are described and measurements to characterize the resultant gamma ray beam are described. For the beam measurements, the inverse square law is investigated and beam uniformity is assessed. A trial calibration of ionization chambers is described. The Am-241 irradiation facility is concluded to be suitable for calibrating secondary standards as part of the calibration service offered for protection level instruments. The umbra part of beam is acceptably uniform for a range of chambers and the measurements obtained were predictable and consistent. This quality will be added to the range of qualities offered as part of the protection level secondary standard calibration service.

  9. High temperature heat capacity of (U, Am)O2±x

    NASA Astrophysics Data System (ADS)

    Epifano, E.; Beneš, O.; Vălu, O. S.; Zappey, J.; Lebreton, F.; Martin, P. M.; Guéneau, C.; Konings, R. J. M.

    2017-10-01

    Mixed uranium and americium dioxides (U, Am)O2±x are candidates as possible transmutation targets for generation IV reactors. In this work, the enthalpy increments of this solid solution were measured in the 470-1750 K temperature range by drop calorimetry for Am/(Am + U) ratios equal to 0.32, 0.39, 0.49, 0.58 and 0.68. Then, the heat capacity functions were obtained by derivation of the enthalpy data. The results of this work were compared to the heat capacity and enthalpy functions reported in the literature for the UO2 [1] and AmO2 [2] binary oxides and for the U0.9Am0.1O2±x, U0.8Am0.2O2±x mixed oxides [3]. From the obtained trend, it was found out that an excess contribution to the enthalpy increment appears for T > 1100 K in the compositions with Am/(Am + U)≥0.4 and a possible explanation attributing this effect to oxygen hypostoichiometry is provided. Finally, to verify the hypothesis, thermodynamic computations based on the CALPHAD method were performed for AmO2-x under air and the results confirmed that the source of the excess contribution is the formation of oxygen vacancies.

  10. Detection of 59Ni at the Lund AMS facility

    NASA Astrophysics Data System (ADS)

    Persson, Per; Kiisk, Madis; Erlandsson, Bengt; Faarinen, Mikko; Hellborg, Ragnar; Skog, Göran; Stenström, Kristina

    2000-10-01

    In the use of small tandem accelerators for accelerator mass spectrometry (AMS), interfering isobars are often troublesome, especially when heavier isotopes such as 59Ni are to be measured. One way to reduce this problem is to combine AMS with the detection of characteristic projectile X-rays. After analysis in the AMS system, the ions are stopped in a suitable target and it is possible to identify the ions by atomic number and thereby separate the isobars. In order to lower the detection limit in the case of 59Ni in stainless steel samples, it is necessary to chemically reduce the content of 59Co in the sample. Further improvements in the reduction of the X-ray background and in the chemical reduction of cobalt have led to nearly a factor of 10 lower detection limit of 59Ni at the Lund AMS facility compared to what has been reported earlier. The content of 59Ni in some steel samples obtained from Swedish nuclear power plants has been measured and the results are presented here.

  11. Photometry and dynamics of the minor mergers AM 1228-260 and AM 2058-381

    NASA Astrophysics Data System (ADS)

    Hernandez-Jimenez, J. A.; Pastoriza, M. G.; Bonatto, C.; Rodrigues, I.; Krabbe, A. C.; Winge, Cláudia

    2015-08-01

    We investigate interaction effects on the dynamics and morphology of the galaxy pairs AM 2058-381 and AM 1228-260. This work is based on r' images and long-slit spectra obtained with the Gemini Multi-Object Spectrograph at the Gemini South Telescope. The luminosity ratio between the main (AM 2058A) and secondary (AM 2058B) components of the first pair is a factor of ˜ 5, while for the other pair, the main (AM 1228A) component is 20 times more luminous than the secondary (AM 1228B). The four galaxies have pseudo-bulges, with a Sérsic index n < 2. Their observed radial velocities profiles (RVPs) present several irregularities. The receding side of the RVP of AM 2058A is displaced with respect to the velocity field model, while there is a strong evidence that AM 2058B is a tumbling body, rotating along its major axis. The RVPs for AM 1228A indicate a misalignment between the kinematic and photometric major axes. The RVP for AM 1228B is quite perturbed, very likely due to the interaction with AM 1228A. NFW halo parameters for AM 2058A are similar to those of the Milky Way and M 31. The halo mass of AM 1228A is roughly 10 per cent that of AM 2058A. The mass-to-light (M/L) of AM 2058 agrees with the mean value derived for late-type spirals, while the low M/L for AM 1228A may be due to the intense star formation ongoing in this galaxy.

  12. A&M. Plot plan of administration and A&M areas. Shows relationships ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    A&M. Plot plan of administration and A&M areas. Shows relationships among administration buildings and to A&M building (TAN-607), railroad turntable. Ralph M. Parsons 902-2&3-ANP-U 3. Date: December 1952. INEEL index code no. 032-0100-00-693-106690 - Idaho National Engineering Laboratory, Test Area North, Scoville, Butte County, ID

  13. Beneficial uses of /sup 241/Am

    SciTech Connect

    Mangeng, C.A.; Thayer, G.R.

    1984-05-01

    This report assesses the uses of /sup 241/Am and the associated costs and supply. The study shows that /sup 241/Am-fueled radioisotope thermoelectric generators in the range of 1 to 5 W electrical provide the most promising use of kilogram amounts of this isotope. For medical uses, where purity is essential, irradiation of /sup 241/Am can produce 97% pure /sup 238/Pu at $21,000/g. Using a pyro-metallurgical process, /sup 241/Am could be recovered from molten salt extraction (MSE) residues at an estimated incremental cost of $83/g adjusted to reflect the disposal costs of waste products. This cost of recovery is less than the $300/g cost for disposal of the /sup 241/Am contained in the MSE residues.

  14. Exotic negative molecules in AMS

    NASA Astrophysics Data System (ADS)

    Golser, Robin; Gnaser, Hubert; Kutschera, Walter; Priller, Alfred; Steier, Peter; Wallner, Anton

    2007-06-01

    "The techniques and equipment developed for AMS studies are well suited for identifying exotic negative ions". With this sentence begins a pioneering paper by Roy Middleton and Jeff Klein (M&K) on small doubly-charged negative carbon clusters [Nucl. Instr. and Meth. B 123 (1997) 532]. M&K were the first to utilize Accelerator Mass Spectrometry to prove the existence of these clusters and a number of other exotic molecules. We review M&K's efforts and show how their work is being continued at other laboratories. The latest developments are: (1) the discovery of long-lived molecular hydrogen anions H2-,D2-and (2) the unambiguous identification of the smallest doubly-charged negative molecule (LiF3)2-. In particular we show new experimental data for D3-, and for (LiF3)2-, and we try to answer the question why M&K's search for this di-anion was unsuccessful.

  15. A case of time-dependent anisotropy of low-field susceptibility (AMS)

    NASA Astrophysics Data System (ADS)

    Borradaile, Graham J.; Geneviciene, Ieva

    2007-07-01

    A suite of non-tectonized, Meso-Proterozoic siliceous crystal tuffs and volcanic breccia with a visible stratification has a modal bulk susceptibility ( k) ˜ 160 μSI [mean; S.D. = 141 μSI; 44 μSI]. Normally, such susceptibilities suffice to make reliable measurements of anisotropy of low field susceptibility (AMS) using AC induction-coil instruments. However, for this suite, time-dependent susceptibility - variations during measurement are large in comparison to susceptibility - differences along different axes through a specimen. Thus, in many specimens, AMS axes determined by routine induction coil measurement in a (Sapphire Instruments SI2B; 19,200 Hz, 60 A/m) measurement procedures are not reproducible. The apparent variation of specimen susceptibility during a single, four minute AMS measurement can > 2 μSI whereas in the same interval the noise-level of our instrument is < 0.2 μSI. Thus, the time-dependence of the specimen-susceptibility is an intrinsic phenomenon due to the characteristics (grain size, domain structure) of the magnetite which dominates susceptibility during measurement and handling. Two procedures improved the reproducibility and stability of AMS axial orientations in some specimens. First, for some specimens, one or two cycles of LTD or AF demagnetization (≤ 15 mT) stabilized AMS axes. (Previous workers have observed that LTD and AF demagnetization may change slightly the AMS of polydomainal magnetite). Of course, exposure to alternating fields is preferably avoided before any AMS study. Second, for some specimens AMS measurement were improved by shielding the induction coil instrument in a large magnetically shielded space (ambient field < 5 nT). Further improvements were achieved by permitting the specimens to relax in side a magnetic shield for 24 h before measurement. The occurrence of time-dependent bulk susceptibility, especially noticeable in its AMS axial orientations is certainly a rare phenomenon and the procedures we used

  16. Reprocessing of 10B-contaminated 10Be AMS targets

    NASA Astrophysics Data System (ADS)

    Simon, K. J.; Pedro, J. B.; Smith, A. M.; Child, D. P.; Fink, D.

    2013-01-01

    10Be accelerator mass spectrometry (AMS) is an increasingly important tool in studies ranging from exposure age dating and palaeo-geomagnetism to the impact of solar variability on the Earth’s climate. High levels of boron in BeO AMS targets can adversely impact the quality of 10Be measurements through interference from the isobar 10B. Numerous methods in chemical sample preparation and AMS measurement have been employed in order to reduce the impact of excessive boron rates. We present details of a method developed to chemically reprocess a set of forty boron-contaminated BeO targets derived from modern Antarctic ice. Previously, the excessive boron levels in these samples, as measured in an argon-filled absorber cell preceding the ionisation detector, had precluded routine AMS measurement. The procedure involved removing the BeO + Nb mixture from the target holders and dissolving the BeO in hot concentrated H2SO4. The solution was then heated with HF to remove the boron as volatile BF3 before re-precipitating as Be(OH)2 and calcining to BeO. This was again mixed with niobium and pressed into fresh target holders. Following reprocessing, the samples gave boron rates reduced by 10-100×, which were sufficiently low and similar to previous successful batches of ice core, snow and associated blank samples, thus allowing a successful 10Be measurement in the absence of any boron correction. Overall recovery of the BeO for this process averaged 40%. Extensive testing of relevant processing equipment and reagents failed to determine the source of the boron. As a precautionary measure, a similar H2SO4 + HF step has been subsequently added to the standard ice processing method.

  17. LLNL/UC AMS facility and research program

    NASA Astrophysics Data System (ADS)

    Davis, J. C.; Proctor, I. D.; Southon, J. R.; Caffee, M. W.; Heikkinen, D. W.; Roberts, M. L.; Moore, T. L.; Turteltaub, K. W.; Nelson, D. E.; Loyd, D. H.; Vogel, J. S.

    1990-12-01

    The Lawrence Livermore National Laboratory (LLNL) and the University of California (UC) now have in operation a large AMS spectrometer built as part of a new multiuser laboratory centered on an FN tandem. AMS measurements are expected to use half of the beam time of the accelerator. LLNL use of AMS is in research on consequences of energy usage. Examples include global warming, geophysical site characterization, radiation biology and dosimetry, and study of mutagenic and carcinogenic processes. UC research activities are in clinical applications, archaeology and anthropology, oceanography, and geophysical and geochemical research. Access is also possible for researchers outside the UC system. The technological focus of the laboratory is on achieving high rates of sample throughput, unattended operation, and advances in sample preparation methods. Because of the expected growth in the research programs and the other obligations of the present accelerator, we are designing a follow-on dedicated facility for only AMS and microprobe analysis that will contain at least two accelerators with multiple spectrometers.

  18. Effects of noise reduction on AM and FM perception.

    PubMed

    Ives, D Timothy; Calcus, Axelle; Kalluri, Sridhar; Strelcyk, Olaf; Sheft, Stanley; Lorenzi, Christian

    2013-02-01

    The goal of noise reduction (NR) algorithms in digital hearing aid devices is to reduce background noise whilst preserving as much of the original signal as possible. These algorithms may increase the signal-to-noise ratio (SNR) in an ideal case, but they generally fail to improve speech intelligibility. However, due to the complex nature of speech, it is difficult to disentangle the numerous low- and high-level effects of NR that may underlie the lack of speech perception benefits. The goal of this study was to better understand why NR algorithms do not improve speech intelligibility by investigating the effects of NR on the ability to discriminate two basic acoustic features, namely amplitude modulation (AM) and frequency modulation (FM) cues, known to be crucial for speech identification in quiet and in noise. Here, discrimination of complex, non-linguistic AM and FM patterns was measured for normal hearing listeners using a same/different task. The stimuli were generated by modulating 1-kHz pure tones by either a two-component AM or FM modulator with patterns changed by manipulating component phases. Modulation rates were centered on 3 Hz. Discrimination of AM and FM patterns was measured in quiet and in the presence of a white noise that had been passed through a gammatone filter centered on 1 kHz. The noise was presented at SNRs ranging from -6 to +12 dB. Stimuli were left as such or processed via an NR algorithm based on the spectral subtraction method. NR was found to yield small but systematic improvements in discrimination for the AM conditions at favorable SNRs but had little effect, if any, on FM discrimination. A computational model of early auditory processing was developed to quantify the fidelity of AM and FM transmission. The model captured the improvement in discrimination performance for AM stimuli at high SNRs with NR. However, the model also predicted a relatively small detrimental effect of NR for FM stimuli in contrast with the average

  19. Innovative Instructional Tools from the AMS

    NASA Astrophysics Data System (ADS)

    Abshire, W. E.; Geer, I. W.; Mills, E. W.; Nugnes, K. A.; Stimach, A. E.

    2016-12-01

    Since 1996, the American Meteorological Society (AMS) has been developing online educational materials with dynamic features that engage students and encourage additional exploration of various concepts. Most recently, AMS transitioned its etextbooks to webBooks. Now accessible anywhere with internet access, webBooks can be read with any web browser. Prior versions of AMS etextbooks were difficult to use in a lab setting, however webBooks are much easier to use and no longer a hurdle to learning. Additionally, AMS eInvestigations Manuals, also in webBook format, include labs with innovative features and educational tools. One such example is the AMS Climate at a Glance (CAG) app that draws data from NOAA's Climate at a Glance website. The user selects historical data of a given parameter and the app calculates various statistics revealing whether or not the results are consistent with climate change. These results allow users to distinguish between climate variability and climate change. This can be done for hundreds of locations across the U.S. and on multiple time scales. Another innovative educational tool used in AMS eInvestigations Manuals is the AMS Conceptual Climate Energy Model (CCEM). The CCEM is a computer simulation designed to enable users to track the paths that units of energy might follow as they enter, move through and exit an imaginary system according to simple rules applied to different scenarios. The purpose is to provide insight into the impacts of physical processes that operate in the real world. Finally, AMS educational materials take advantage of Google Earth imagery to reproduce the physical aspects of globes, allowing users to investigate spatial relationships in three dimensions. Google Earth imagery is used to explore tides, ocean bottom bathymetry and El Nino and La Nina. AMS will continue to develop innovative educational materials and tools as technology advances, to attract more students to the Earth sciences.

  20. Space Station Live: First Findings from the AMS

    NASA Image and Video Library

    PAO Officer Kyle Herring interviews Alpha Magnetic Spectrometer (AMS) Project Manager Trent Martin about the first findings from the AMS. A small team from Johnson Space Center collaborates with AM...

  1. Space Station Live: Installing the AMS

    NASA Image and Video Library

    PAO Officer Kyle Herring interviews NASA astronaut Mike Fincke about his contribution during STS-134, the shuttle mission that installed the Alpha Magnetic Spectrometer (AMS) in May 2011. As a miss...

  2. Challenge of COPD: Am I at Risk?

    MedlinePlus

    ... please turn JavaScript on. Feature: The Challenge of COPD Am I at Risk? Past Issues / Fall 2014 ... or the American Lung Association's COPD information section. COPD Learn More Breathe Better ® Program The COPD Learn ...

  3. Stomach Flu: How Long Am I Contagious?

    MedlinePlus

    ... long am I contagious if I have the stomach flu? Answers from James M. Steckelberg, M.D. You can ... more, depending on which virus is causing your stomach flu (gastroenteritis). A number of viruses can cause ...

  4. On the Light Curves of AM CVn

    NASA Astrophysics Data System (ADS)

    Smak, J.

    2017-03-01

    Light curves of AM CVn are analyzed by decomposing them into their Fourier components. The amplitudes of the fundamental mode and overtones of the three components: the superhumps, the negative superhumps and the orbital variations, are found to be variable. This implies that variations in the shape of the observed light curve of AM CVn are not only due to the interference between those components, but also due to the intrinsic variability within these components.

  5. AMS results on the fluxes of light nuclei in cosmic rays

    NASA Astrophysics Data System (ADS)

    Bertucci, Bruna; AMS Collaboration

    2017-01-01

    AMS-02 is a wide acceptance high-energy physics experiment installed on the International Space Station in May 2011 and it has been operating continuously since then. AMS-02 is able to separate cosmic rays light nuclei species (1 <= Z <= 8) with contaminations less than 10-3 thanks to the redundant measurement of the particle charge in eight silicon tracker layers, four scintillator planes and the Ring Imaging Cherenkov detector. The accurate measure of their spectrum in the GeV-TeV range is performed by the magnetic spectrometer with a maximum detectable rigidity of 2-3 TV. Precise measurements from AMS will be presented, including proton, helium, boron to carbon flux ratio, and highlights of ongoing analyses discussed. On behalf of the AMS Collaboration.

  6. SCADA -- AM/FM interface: Platforms, technology

    SciTech Connect

    Gilbert, R.F. )

    1994-05-01

    Efficient utility operations is enhanced by close interoperation between automated mapping/facility management (AM/FM) and supervisory control and data acquisition (SCADA) systems. Important benefits of such integration are improvements in service quality and reduced maintenance costs. Development of an AM/FM -- SCADA interface to provide automatic database and display generation for SCADA through AM/FM functions is continuing by Valmet Automation. To minimize or eliminate vendor-dependence, the AM/FM-SCADA interface is compliant with the Electric Power Research Institute's (EPRI) utility communication architecture (UCA). The utility industry is changing at an unprecedented rate. To remain a leader, or even to keep pace, utilities must be flexible and innovative. Competition forces companies to become more streamlined and efficient. These forces make the requirements for automation go beyond simple SCADA. Among several developing trends in the industry is the emergence of AM/FM. Collectively, these trends indicate the need to increase efficiency in the design, operation and maintenance of the transmission and distribution system. To accomplish its mission, SCADA and AM/FM must be a highly integrated system to provide timely information to its users. Open systems, the client-server paradigm and better information integration tools facilitate meeting these needs. UCA specification provides the technological glue, to achieve application integration between heterogeneous systems.

  7. The use of MOX caramel fuel mixed with (241)Am, (242m)Am and (243)Am as burnable absorber actinides for the MTR research reactors.

    PubMed

    Shaaban, Ismail; Albarhoum, Mohamad

    2017-07-01

    The MOX (UO2&PuO2) caramel fuel mixed with (241)Am, (242m)Am and (243)Am as burnable absorber actinides was proposed as a fuel of the MTR-22MW reactor. The MCNP4C code was used to simulate the MTR-22MW reactor and estimate the criticality and the neutronic parameters, and the power peaking factors before and after replacing its original fuel (U3O8-Al) by the MOX caramel fuel mixed with (241)Am, (242m)Am and (243)Am actinides. The obtained results of the criticality, the neutronic parameters, and the power peaking factors for the MOX caramel fuel mixed with (241)Am, (242m)Am and (243)Am actinides were compared with the same parameters of the U3O8-Al original fuel and a maximum difference is -6.18% was found. Additionally, by recycling 2.65% and 2.71% plutonium and (241)Am, (242m)Am and (243)Am actinides in the MTR-22MW reactor, the level of (235)U enrichment is reduced from 4.48% to 3% and 2.8%, respectively. This also results in the reduction of the (235)U loading by 32.75% and 37.22% for the 2.65%, the 2.71% plutonium and (241)Am, (242m)Am and (243)Am actinides, respectively. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. A&M. Aerial view of turntable and A&M building (TAN607). Pool, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    A&M. Aerial view of turntable and A&M building (TAN-607). Pool, hot shop, cold shop, and machine shop are completed. Track leading to left edge of view goes to the IET. Ancient lake shoreline and berm beyond A&M building. Camera facing east. Administrative buildings beyond berm. Date: November 24, 1954. INEEL negative no. 13205 - Idaho National Engineering Laboratory, Test Area North, Scoville, Butte County, ID

  9. The AMS-02 Proton Spectra and the Geomagnetic Field

    NASA Astrophysics Data System (ADS)

    Bobik, P.; Boschini, M. J.; Consolandi, C.; Della Torre, S.; Gervasi, M.; Grandi, D.; Kudela, K.; Pensotti, S.; Rancoita, P. G.

    2011-06-01

    We evaluate {\\rlap {- a}} the AMS-02 spectra for the year 2012 using the HelMod {\\rlap {- a}} software that reproduces the effect of the Heliospheric Modulation for different periods and polarities. Once {\\rlap {- a}} the Local Interstellar Spectrum (LIS) is given, we can obtain a modulated spectrum at Earth (1 AU) using the measured solar conditions (tilt angle apha, solar wind velocity V) and the extrapolated diffusion coefficients K0 (from Sunspot numbers). This calculations provide a flux of the primary (PCR) cosmic rays, protons, outside the geomagnetic field, that must be compared to the measured one at the low Earth orbit (about 400 km altitude). A back-tracking procedure of simulated protons entering the AMS-02 spectrometer has provided the fraction of allowed (and hence, forbidden) trajectories of the PCRs. Consequently, it has allowed the determination of the so-called Transmission Function (TF) which was able to describe the properties of the PCR transport from the Earth's magnetopause (i.e. the modulated primary spectrum at 1 AU) to the atmosphere and finally the fluxes of the PCRs in 10 geomagnetic regions for the AMS-02 observations.

  10. 26Al at the AMS facility in Lund

    NASA Astrophysics Data System (ADS)

    Faarinen, Mikko; Bazhal, Sergei; Falkengren-Grerup, U.; Hellborg, Ragnar; Kiisk, Madis; Magnusson, Carl Erik; Persson, Per; Skog, Göran; Stenström, Kristina

    2004-08-01

    To broaden the AMS programme in Lund by including Al studies, a new injector has been installed and tested at the 3 MV Pelletron accelerator. Detailed optical calculations have been performed to obtain maximum mass and energy resolution. The design of the injector, the improvement in the resolution compared to the old injector, as well as preliminary tests with a 26Al-beam, are presented. By using accelerator mass spectrometry (AMS) to measure the long-lived aluminium isotope 26Al it has become possible to study the uptake, distribution and retention of aluminium in biological system under physiologically realistic conditions. Results from a pilot project on 26Al in wheat plants are presented.

  11. The Earth Observing System AM Spacecraft - Thermal Control Subsystem

    NASA Technical Reports Server (NTRS)

    Chalmers, D.; Fredley, J.; Scott, C.

    1993-01-01

    Mission requirements for the EOS-AM Spacecraft intended to monitor global changes of the entire earth system are considered. The spacecraft is based on an instrument set containing the Advanced Spaceborne Thermal Emission and Reflection radiometer (ASTER), Clouds and Earth's Radiant Energy System (CERES), Multiangle Imaging Spectro-Radiometer (MISR), Moderate-Resolution Imaging Spectrometer (MODIS), and Measurements of Pollution in the Troposphere (MOPITT). Emphasis is placed on the design, analysis, development, and verification plans for the unique EOS-AM Thermal Control Subsystem (TCS) aimed at providing the required environments for all the onboard equipment in a densely packed layout. The TCS design maximizes the use of proven thermal design techniques and materials, in conjunction with a capillary pumped two-phase heat transport system for instrument thermal control.

  12. OSO-8 X-ray observations of AM Herculis

    NASA Technical Reports Server (NTRS)

    Swank, J. H.; Lampton, M.; Boldt, E.; Holt, S. S.; Serlemitsos, P. J.

    1977-01-01

    Hard X-ray observations of the binary system AM Her were coincident with soft X-ray and ground-based optical measurements. In the 2-60 KeV band, variability was detected with an eclipse during phases 0.5 to 0.7 with respect to the 0. d 12892 period optical minima, synchronous with the known soft X-ray eclipse. The 2-60 KeV uneclipsed flux was 9.5 x 10 to the minus 10th power erg sq cm/sec, of which 86% lies above 10 keV. Thus AM Her contains a hard source located near the similarly eclipsed soft X-ray source. The X-ray data are interpreted in terms of thermal bremsstrahlung from accretion onto a white dwarf.

  13. AMS,Chang-Diaz works with computers in the middeck

    NASA Image and Video Library

    2016-08-24

    STS091-378-028 (2-12 June 1998) --- Astronaut Franklin R. Chang-Diaz, payload commander, inputs data on a laptop computer associated with the Alpha Magnetic Spectrometer (AMS) hardware located in the aft cargo bay. Reference JSC photo number STS091-367-033, which shows the hardware as seen from Russia's Mir space station, which was docked with Discovery at the time. AMS is the first large magnet experiment ever placed in Earth orbit. The scientific goal of this high-energy physics experiment is to increase our understanding of the composition and origin of the universe. It is designed to search for and measure charged particles, including antimatter, outside Earth's atmosphere. The charge of such particles can be identified by their trajectories in a magnetic field.

  14. Radiocarbon AMS at IOP: System improvements and dating of groundwater from Bhadrak district, Orissa

    NASA Astrophysics Data System (ADS)

    Prasad, G. V. Ravi; Dutta, K.; Ray, D. K.

    2008-04-01

    The radiocarbon AMS facility at Institute of Physics, Bhubaneswar is based on a 3 MV tandem accelerator. In this paper, we present the recent improvements to the AMS system at this general purpose accelerator facility. We report an effective method of overcoming terminal voltage instability often met with in switching between AMS and other modes of operation of the accelerator. We report the radiocarbon measurements made on connate groundwater samples from the Bhadrak district of Orissa state (eastern India) to identify the regions that require artificial recharge.

  15. Quantitative metabolism using AMS: Choosing a labeled precursor

    PubMed Central

    Links, Jennifer; Palmblad, Magnus; Ognibene, Ted; Turteltaub, Ken; Bench, Graham

    2009-01-01

    Biological radioisotope studies suffer from a lack of sensitive measurement techniques and therefore traditionally require large amounts of labeled material to produce a measurable signal. Such quantities of materials are often significantly higher than naturally-occurring levels preventing these studies from replicating physiological conditions. AMS affords the sensitivity necessary to perform biological radioisotope studies with low levels of labeled material that preserve physiological conditions. The choice of labeled material can substantially affect the ease of interpretation and comprehensiveness of these studies. Here, the benefits and limitations of whole-cell labeling with 14C-glucose and targeted pathway labeling with 14C-nicotinic acid are discussed and compared. PMID:20368758

  16. A method for determining Am-241 activity for large area contamination.

    PubMed

    Wilhelm, Emilien; Arbor, Nicolas; Gutierrez, Sébastien; Ménard, Stéphanie; Nourreddine, Abdel-Mjid

    2017-01-01

    Airborne gamma-ray spectrometry system HELINUC™ is used for different missions. Although well-developed for estimation of high energy emitters' activity, it is rarely used for low energy emitters. A new method for the determination of Am-241 activity over extended sites based both on statistical analysis of spectra and deconvolution of Am-241 signal with a reference library is presented. Results show a lowering of the detection threshold and a good agreement with ground level measurements.

  17. 33 CFR 103.300 - Area Maritime Security (AMS) Committee.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Area Maritime Security (AMS... SECURITY MARITIME SECURITY MARITIME SECURITY: AREA MARITIME SECURITY Area Maritime Security (AMS) Committee § 103.300 Area Maritime Security (AMS) Committee. (a) The AMS Committee is established under the...

  18. AMS-02 antiprotons: implications for dark matter

    NASA Astrophysics Data System (ADS)

    Boudaud, Mathieu

    2016-05-01

    Using the updated proton and helium fluxes just released by the Ams-02 experiment we reevaluate the secondary astrophysical antiproton to proton ratio and its uncertainties, and compare it with the ratio preliminarly reported by AMS-02. We find no unambiguous evidence for a significant excess with respect to expectations. Yet, some preference for a flatter energy dependence of the diffusion coefficient (with respect to the Med benchmark often used in the literature) starts to emerge. Finally, we provide a first assessment of the room left for exotic components such as Galactic Dark Matter annihilation, deriving new stringent constraints.

  19. A comprehensive appraisal of 241Am in soils around Rocky Flats, Colorado.

    PubMed

    Litaor, M I; Allen, L

    1996-09-01

    Soils east of Rocky Flats Plant (RFETS) near Golden, Colorado, were contaminated with actinides because of accidental release of oils laden with plutonium isotopes. Consequently, these soils were contaminated by 241Am due to radioactive decay of 241Pu (t1/2 = 14.4 y). A spatial analysis of 241Am activity in soils east of RFETS was conducted to elucidate the magnitude and the mode of 241Am dispersion in the soil environment. 241Am activity of 178 soil samples ranged from 0.037 Bq kg-1 to 10,004 Bq kg-1 with a mean of 214 Bq kg-1, median of 7.28 Bq kg-1, standard deviation of 942 Bq kg-1, and a coefficient of variation of 4.3. Spatial analysis of 241Am in soils around RFETS was conducted using indicator kriging, which is a nonparametric technique especially suitable to model a conditional cumulative distribution function (ccdf) of highly skewed environmental data such as 241Am. The ccdf was used to generate an E-type (mean of the conditional cdf) surface. The resulted surfaces were consistent with the hypothesis that the westerly winds were the dominant mechanism of americium dispersal. The spatial distribution and dispersal mechanisms of 241Am were similar to those of 239+240Pu. The ccdf was also used to construct probability of exceedence maps of 241Am in soils. For the purpose of this report two threshold values for the probability maps were selected: (1) the mean measured background activity of 241Am (0.4 Bq kg-1), and (2) the programmatic preliminary remediation goal for residential occupancy scenario (87.7 Bq kg-1). The probability-of-exceedance maps provide estimates of spatial uncertainty associated with each threshold. The E-type maps in conjunction with the probability-of-exceedance maps provide a robust framework for future cleanup options and land use decisions.

  20. Behavior of 241Am in fast reactor systems - a safeguards perspective

    SciTech Connect

    Beddingfield, David H; Lafleur, Adrienne M

    2009-01-01

    Advanced fuel-cycle developments around the world currently under development are exploring the possibility of disposing of {sup 241}Am from spent fuel recycle processes by burning this material in fast reactors. For safeguards practitioners, this approach could potentially complicate both fresh- and spent-fuel safeguards measurements. The increased ({alpha},n) production in oxide fuels from the {sup 241}Am increases the uncertainty in coincidence assay of Pu in MOX assemblies and will require additional information to make use of totals-based neutron assay of these assemblies. We have studied the behavior of {sup 241}Am-bearing MOX fuel in the fast reactor system and the effect on neutron and gamma-ray source-terms for safeguards measurements. In this paper, we will present the results of simulations of the behavior of {sup 241}Am in a fast breeder reactor system. Because of the increased use of MOX fuel in thermal reactors and advances in fuel-cycle designs aimed at americium disposal in fast reactors, we have undertaken a brief study of the behavior of americium in these systems to better understand the safeguards impacts of these new approaches. In this paper we will examine the behavior of {sup 241}Am in a variety of nuclear systems to provide insight into the safeguards implications of proposed Am disposition schemes.

  1. 7 CFR 1221.201 - Administrator, AMS.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 10 2014-01-01 2014-01-01 false Administrator, AMS. 1221.201 Section 1221.201 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (MARKETING AGREEMENTS AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE SORGHUM PROMOTION, RESEARCH,...

  2. 7 CFR 1221.201 - Administrator, AMS.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 10 2013-01-01 2013-01-01 false Administrator, AMS. 1221.201 Section 1221.201 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (MARKETING AGREEMENTS AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE SORGHUM PROMOTION, RESEARCH,...

  3. 7 CFR 1221.201 - Administrator, AMS.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 10 2011-01-01 2011-01-01 false Administrator, AMS. 1221.201 Section 1221.201 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (MARKETING AGREEMENTS AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE SORGHUM PROMOTION, RESEARCH,...

  4. 7 CFR 1221.201 - Administrator, AMS.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 10 2012-01-01 2012-01-01 false Administrator, AMS. 1221.201 Section 1221.201 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (MARKETING AGREEMENTS AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE SORGHUM PROMOTION, RESEARCH,...

  5. Pro-Am Collaboration and the AAVSO

    NASA Astrophysics Data System (ADS)

    Henden, A.

    2006-04-01

    Professionals need to be aware that there is a valuable resource available and waiting to be used -- the amateur astronomy community. We give some examples of how pro-am collaborations have worked in the past, indicate the advantages and disadvantages of such collaborations, and suggest methods by which a professional can find and work effectively with amateur astronomers.

  6. 7 CFR 1220.601 - Administrator, AMS.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 10 2014-01-01 2014-01-01 false Administrator, AMS. 1220.601 Section 1220.601 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (MARKETING AGREEMENTS AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE SOYBEAN PROMOTION, RESEARCH,...

  7. 7 CFR 1220.601 - Administrator, AMS.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 10 2012-01-01 2012-01-01 false Administrator, AMS. 1220.601 Section 1220.601 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (MARKETING AGREEMENTS AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE SOYBEAN PROMOTION, RESEARCH,...

  8. 7 CFR 1220.601 - Administrator, AMS.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 10 2013-01-01 2013-01-01 false Administrator, AMS. 1220.601 Section 1220.601 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (MARKETING AGREEMENTS AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE SOYBEAN PROMOTION, RESEARCH,...

  9. 7 CFR 1220.601 - Administrator, AMS.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 10 2011-01-01 2011-01-01 false Administrator, AMS. 1220.601 Section 1220.601 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (MARKETING AGREEMENTS AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE SOYBEAN PROMOTION, RESEARCH,...

  10. 7 CFR 1220.601 - Administrator, AMS.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 10 2010-01-01 2010-01-01 false Administrator, AMS. 1220.601 Section 1220.601 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (MARKETING AGREEMENTS AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE SOYBEAN PROMOTION, RESEARCH,...

  11. Chemical thermodynamic representation of AmO 2- x

    NASA Astrophysics Data System (ADS)

    Thiriet, C.; Konings, R. J. M.

    2003-08-01

    The AmO 2- x solid solution data set for the dependence of the oxygen potential on the composition, x, and temperature was retrieved from the literature and represented by a thermodynamic model. The data set was analysed by least-squares using equations derived from the classical thermodynamic theory for the solid solution of a solute in a solvent. Two representations of the AmO 2- x data were used, namely the Am 5/4O 2-AmO 2 and AmO 3/2-AmO 2 solid solution. No significant difference was found between the two, and the Am 5/4O 2-AmO 2 solution was preferred on the basis of the phase diagram. From the results the Gibbs energy of formation of Am 5/4O 2 has been derived.

  12. CAOS spectroscopy of Am stars Kepler targets

    NASA Astrophysics Data System (ADS)

    Catanzaro, G.; Ripepi, V.; Biazzo, K.; Busá, I.; Frasca, A.; Leone, F.; Giarrusso, M.; Munari, M.; Scuderi, S.

    2015-07-01

    The Kepler space mission and its K2 extension provide photometric time series data with unprecedented accuracy. These data challenge our current understanding of the metallic-lined A stars (Am stars) for what concerns the onset of pulsations in their atmospheres. It turns out that the predictions of current diffusion models do not agree with observations. To understand this discrepancy, it is of crucial importance to obtain ground-based spectroscopic observations of Am stars in the Kepler and K2 fields in order to determine the best estimates of the stellar parameters. In this paper, we present a detailed analysis of high-resolution spectroscopic data for seven stars previously classified as Am stars. We determine the effective temperatures, surface gravities, projected rotational velocities, microturbulent velocities and chemical abundances of these stars using spectral synthesis. These spectra were obtained with CAOS, a new instrument recently installed at the observing station of the Catania Astrophysical Observatory on Mt Etna. Three stars have already been observed during quarters Q0-Q17, namely: HD 180347, HD 181206 and HD 185658, while HD 43509 was already observed during K2 C0 campaign. We confirm that HD 43509 and HD 180347 are Am stars, while HD 52403, HD 50766, HD 58246, HD 181206 and HD 185658 are marginal Am stars. By means of non-LTE (local thermodynamic equilibrium) analysis, we derived oxygen abundances from O I λ7771-5 Å triplet and we also discussed the results obtained with both non-LTE and LTE approaches.

  13. Liposomal amphotericin B, AmBisome.

    PubMed

    Hay, R J

    1994-05-01

    The unilamellar liposomal formulation of amphotericin B, AmBisome, is composed of hydrogenated soy phosphatidylcholine, distearoyl phosphatidylglycerol and cholesterol. Early studies of its efficacy in an open design showed that remissions could be induced in candidosis and aspergillosis and that doses of up to 5 mg/kg could be used. Adverse events were infrequent, with the main abnormality seen being hypokalaemia in about 18% of patients. Subsequent developments have extended this work. AmBisome has been used in two open studies of patients with invasive aspergillosis; in one of these remission was achieved in 77% of 17 patients with confirmed infection who had failed to respond to conventional amphotericin B. In AIDS patients with cryptococcosis AmBisome given for 6 weeks at 3 mg/kg daily produced mycological remission of meningitis in 67%. Other infections treated with the drug include zygomycete (mucormycosis) and Fusarium infections. AmBisome has also been used as preventative therapy in bone marrow transplant recipients and was found to reduce fungal colonisation rates. There were fewer systemic fungal infections in the treated versus placebo groups although this did not achieve statistical significance. Lack of renal and liver toxicity or anaemia has been confirmed in subsequent studies. In addition febrile reactions to the AmBisome are rare. The drug has also been used effectively in children, including infants, with systemic fungal infections. In visceral leishmaniasis patients, including HIV positive individuals, remissions have been obtained using drug regimens of 1-2 mg/kg of 2.1 days and 3 mg/kg for 10 days.

  14. A&M. TAN607. Elevation for secondphase expansion of A&M Building. Work ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    A&M. TAN-607. Elevation for second-phase expansion of A&M Building. Work areas south of the Carpentry Shop. High-bay shop, decontamination room at south-most end. Approved by INEEL Classification Office for public release. Ralph M. Parsons 1299-5-ANP/GE-3-607-A 106. Date: August 1956. INEEL index code no. 034-0607-00-693-107166 - Idaho National Engineering Laboratory, Test Area North, Scoville, Butte County, ID

  15. A&M. A&M building (TAN607). Camera facing east. From left to ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    A&M. A&M building (TAN-607). Camera facing east. From left to right, pool section, hot shop, cold shop, and machine shop. Biparting doors to hot shop are in open position behind shroud. Four rail tracks lead to hot shop and cold shop. Date: August 20, 1954. INEEL negative no. 11706 - Idaho National Engineering Laboratory, Test Area North, Scoville, Butte County, ID

  16. Dependence of the AmII′p Proline Raman Band on Peptide Conformation

    PubMed Central

    Ahmed, Zeeshan; Myshakina, Nataliya S.; Asher, Sanford A.

    2009-01-01

    We utilized UV-resonance Raman (UVRR) measurements and density functional theory (DFT) calculations to relate that the AmII′p frequency to the ψ-angle. The AmII′p frequency shifts by ∼ 25 cm-1 as the ψ-angle is varied over allowed angles of the pro peptide bond. The AmII′p frequency does not show any significant dependence on the φ-dihedral angle. The conformation sensitivity of the AmII′p frequency derives from conformation-induced changes in the planarity of the Pro peptide bond; ψ angles changes push the amide nitrogen out of the peptide bond plane. We use this AmII′p frequency dependence on the ψ-angle to track temperature-induced conformation changes in a polyproline peptide. The temperature-induced 7 cm-1 downshift in the AmII′p frequency of the polyproline peptide results from a ∼45° rotation of the ψ dihedral angle from ψ = 145° (ideal PPII conformation) to ψ = 100° (collapsed PPII conformation). PMID:19627094

  17. [Removal Congo Red from Aqueous Solution Using Poly (AM-co-DVB)].

    PubMed

    Zhang, Luan-luan; Liao, Yun-wen; Gao, He-jun; Wang, Zhong-zhi; Shuai, Chao

    2015-06-01

    Poly(AM-co-DVB) was synthesized by acrylamide(AM) and divinylbenzene(DVB) via the crosslinking reaction. The microscope structure and thermal stability of Poly(AM-co-DVB) were characterized by FT-IR, SEM and TG. Congo red (CR) was used to measure the adsorptive capacity of Poly (AM-co-DVB). The effects of initial pH, contact time and temperature on the adsorption of CR on Poly (AM-co-DVB) were investigated in this work. The kinetics, equilibrium, and thermodynamics of the adsorption process were also discussed. The results showed that the maximum adsorption capacities were 319.1 mg x g(-1) at pH = 7.25 and contact time = 3 h. The adsorption kinetics was well fitted by a pseudo-second-order model and the adsorption isotherms agreed well with the Langmuir model. The adsorption process was spontaneous process. Above all, the adsorption capacity of Poly (AM-co-DVB) on Congo red is significant.

  18. Determination of plutonium in environmental samples by AMS and alpha spectrometry.

    PubMed

    Hrnecek, E; Steier, P; Wallner, A

    2005-01-01

    Environmental samples from nuclear weapons test sites at the atolls of Mururoa and Fangataufa (French Polynesia, south Pacific) have been analyzed for their content of plutonium isotopes by applying the independent techniques of decay counting (Alpha Spectrometry) and accelerator mass spectrometry (AMS). Here, we propose the combination of both techniques which results in a maximum of information on the isotopic signature of Pu in environmental samples. Plutonium was chemically separated from the bulk material by anion exchange. (242)Pu was used as an internal standard for both AMS and alpha spectrometry. The samples for alpha spectrometry were prepared by micro-precipitation with NdF(3). After alpha spectrometry, the samples were reprocessed for AMS. Pu was co-precipitated with Fe(OH)(3) and finally, solid samples were prepared. At the VERA (Vienna Environmental Research Accelerator) facility, the various Pu isotopes were separated by their isotopic masses and quantified by the AMS technique. A good agreement of the results obtained from the AMS measurements was found with those obtained from Alpha Spectrometry. Overall, the data agree on average within 10% of each other. Isotope ratios for (238)Pu, (239)Pu and (240)Pu can be extracted from our investigations. Alpha spectrometry delivers data for the (238)Pu and the combination of ((239+240))Pu concentrations in those samples. In addition, the AMS technique provides information on the individual concentrations of (240)Pu and (239)Pu.

  19. Does AMS data from micaceous quartzite provide information about shape of the strain ellipsoid?

    NASA Astrophysics Data System (ADS)

    Mamtani, Manish A.; Vishnu, C. S.

    2012-04-01

    Anisotropy of magnetic susceptibility (AMS) in micaceous quartzites with mean susceptibility ( K m) >50 × 10-6 SI units is known to be on account of the orientation distribution of the para/ferromagnetic minerals (e.g. micas, magnetite), which comprise the minor phase in the rocks. However, the strain in such deformed micaceous quartzites is dominantly accommodated by the quartz grains, which are the major phase in them. The objective of this paper is to explore the extent to which AMS data from micaceous quartzites provide information about the shape of the strain ellipsoid. AMS analysis of 3 quartzite blocks is performed, and the shape of the AMS ellipsoid is recorded to be oblate. From AMS data, the three principal planes of the AMS ellipsoid are identified in each block and thin sections are prepared along them. Quartz grain shape (aspect ratio, R q), intensity of quartz and mica shape preferred orientation (κq and κmi, respectively) and 2D strain ( E) recorded by quartz are measured in each section. R q, κq, κmi and E are all noted to be minimum in the section parallel to the magnetic foliation plane as compared to the other two sections. This indicates that the quartz grains have oblate shapes in 3D and accommodated flattening strain, which is similar to the shape of the AMS ellipsoid. The role of mica in causing Zener drag and pinning of quartz grain boundaries is discussed. It is concluded that during progressive deformation, migration of pinned grain boundaries is inhibited. This causes enhanced recrystallization at the grain boundaries adjacent to the pinned ones, thus guiding the shape modification of quartz grains. A strong correlation is demonstrated between κq and κmi as well as κmi and E. It is inferred that fabric evolution of quartz was controlled by mica. Hence, the shape of the AMS ellipsoid, which is on account of mica, provides information about shape of the strain ellipsoid.

  20. Seven Passive 1-h Hypoxia Exposures Do Not Prevent AMS in Susceptible Individuals.

    PubMed

    Faulhaber, Martin; Pocecco, Elena; Gatterer, Hannes; Niedermeier, Martin; Huth, Maike; Dünnwald, Tobias; Menz, Verena; Bernardi, Luciano; Burtscher, Martin

    2016-12-01

    The present study evaluated the effects of a preacclimatization program comprising seven passive 1-h exposures to 4500-m normobaric hypoxia on the prevalence and severity of acute mountain sickness (AMS) during a subsequent exposure to real high altitude in persons susceptible to AMS. The project was designed as a randomized controlled trial including 32 healthy female and male participants with known susceptibility to AMS symptoms. After baseline measurements, participants were randomly assigned to the hypoxia or the control group to receive the preacclimatization program (seven passive 1-h exposures within 7 d to normobaric hypoxia or sham hypoxia). After completing preacclimatization, participants were transported (bus, cog railway) to real high altitude (3650 m, Mönchsjoch Hut, Switzerland) and stayed there for 45 h (two nights). Symptoms of AMS and physiological responses were determined repeatedly. AMS incidence and severity did not significantly differ between groups during the high-altitude exposure. In total, 59% of the hypoxia and 67% of the control group suffered from AMS at one or more time points during the high-altitude exposure. Hypoxic and hypercapnic ventilatory responses were not affected by the preacclimatization program. Resting ventilation at high altitude tended to be higher (P = 0.06) in the hypoxia group compared with the control group. No significant between-group differences were detected for heart rate variability, arterial oxygen saturation, and hematological and ventilatory parameters during the high-altitude exposure. Preacclimatization using seven passive 1-h exposures to normobaric hypoxia corresponding to 4500 m did not prevent AMS development during a subsequent high-altitude exposure in AMS-susceptible persons.

  1. AMS in basalts: is there a need for a-priori demagnetization?

    NASA Astrophysics Data System (ADS)

    Schoebel, Stefan; de Wall, Helga; Rolf, Christian

    2013-04-01

    One of the most prominent applications of anisotropy of magnetic susceptibility (AMS) measurements is the evaluation of flow fabrics in basalts. Basalts often contain Fe-Ti oxides with variations in grain/domain size fractions due to their variable cooling history. The origin of AMS in such rock types is of complex nature. Crystal shape, magneto-crystalline anisotropy and magnetic interactions are considered as the most influential parameters. It is still under debate if a remanent magnetization, commonly strong in such basalts, can influence the low-field AMS measurements and therefore bias the magnetic fabric interpretation. For this key study lava flows from the Malwa Plateau, the northern part of the Deccan Large Igneous Province in India have been investigated. Specimens were demagnetized using a static 3-axial and a tumbling device (peak fields of 100 mT). The AMS was measured before and after the respective demagnetizing experiment. Scalar AMS parameters and orientation of the principle axes change during the experiments: Mean susceptibility rises due to demagnetization, the shape factor T and the corrected magnetic anisotropy P' show systematic change. This behavior points to a significant influence of remanence vector on AMS. In multi-domain (MD) and pseudo-single-domain (PSD)-grains, axial-demagnetization will align the domain walls according to the applied field. Especially specimens showing a normal magnetic fabric react very sensitive to changes in the domain structure. κmax will get aligned parallel to the last applied field and the other principle magnetic axes will follow the orthogonal geometry of the field. Specimens with an inverse magnetic fabric can also be affected by the demagnetization. However, inverse specimens with an apparent high fraction of single-domain (SD)-particles show no redistribution of their principle axes. Demagnetization with a tumbling device will not impress a direction on the AMS but will remove the magnetic remanence in

  2. Environmental radiation protection studies related to nuclear industries, using AMS

    NASA Astrophysics Data System (ADS)

    Hellborg, Ragnar; Erlandsson, Bengt; Faarinen, Mikko; Hâkansson, Helena; Hâkansson, Kjell; Kiisk, Madis; Magnusson, Carl-Erik; Persson, Per; Skog, Göran; Stenström, Kristina; Mattsson, Sören; Thornberg, Charlotte

    2001-07-01

    14C is produced in nuclear reactors during normal operation and part of it is continuously released into the environment. Because of the biological importance of carbon and the long physical half-life of 14C it is of interest to study these releases. The 14C activity concentrations in the air and vegetation around some Swedish as well as foreign nuclear facilities have been measured by accelerator mass spectrometry (AMS). 59Ni is produced by neutron activation in the stainless steel close to the core of a nuclear reactor. The 59Ni levels have been measured in order to be able to classify the different parts of the reactor with respect to their content of long-lived radionuclides before final storage. The technique used to measure 59Ni at a small accelerator such as the Lund facility has been developed over the past few years and material from the Swedish nuclear industry has been analyzed.

  3. Signal Enhancement in AM-FM Interference

    DTIC Science & Technology

    1994-05-17

    the short-time linear assumption, it provides a good test of the suppression algorithm. A 10-ms Hamming window, a 4-ms frame, and a 2048-point DFT...complex suppression with a different test signal consisting of the AM-FM interference added to an information signal generated from a closing stapler...1st The results of an informal listening test are also listed in Table 1, based on the judgment of interference reduction and clarity of the information

  4. Binaries among AP and AM stars

    NASA Astrophysics Data System (ADS)

    North, P.; Ginestet, N.; Carquillat, J.-M.; Carrier, F.; Udry, S.

    1998-04-01

    The results of long-term surveys of radial velocities of cool Ap and Am stars are presented. There are two samples, one of about 100 Ap stars and the other of 86 Am stars. Both have been observed with the CORAVEL scanner from Observatoire de Haute-Provence (CNRS), France. The conspicuous lack of short-period binaries among cool Ap stars seems confirmed, although this may be the result of an observational bias; one system has a period as short as 1.6 days. A dozen new orbits could be determined, including that of one SB2 system. Considering the mass functions of 68 binaries from the literature and from our work, we conclude that the distribution of the mass ratios is the same for the Bp-Ap stars than for normal G dwarfs. Among the Am stars, we found 52 binaries, i.e. 60%; an orbit could be computed for 29 of them. Among these 29, there are 7 SB2 systems, one triple and one quadruple system. The 21 stars with an apparently constant radial velocity may show up later as long-period binaries with a high eccentricity. The mass functions of the SB1 systems are compatible with cool main-sequence companions, also suggested by ongoing spectral observations.

  5. 50 CFR 648.233 - Spiny dogfish Accountability Measures (AMs).

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE FISHERIES OF THE NORTHEASTERN UNITED STATES...-annual period described in § 648.232(e)(1) will be harvested and shall close the EEZ to fishing for...

  6. 50 CFR 648.163 - Bluefish Accountability Measures (AMs).

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... outlined in § 648.162(b)(2), then the following procedure will be followed: (1) If biomass is below the... estimate of biomass is below the BMSY threshold (i.e., B/BMSY is less than 0.5), the stock is under a... possible thereafter, once catch data are available, as a single-year adjustment. (2) If biomass is above...

  7. α decay of 97249Bk and levels in 95245Am

    NASA Astrophysics Data System (ADS)

    Ahmad, I.; Greene, J. P.; Kondev, F. G.; Zhu, S.; Carpenter, M. P.; Janssens, R. V. F.; Boll, R. A.; Ezold, J. G.; Van Cleve, S. M.; Browne, E.

    2013-05-01

    α decay of 249Bk has been investigated by measuring its α and γ-ray spectra, both in singles and in coincidence modes. The α spectrum of a freshly purified 249Bk sample was measured with a high-resolution, double-focusing magnetic spectrometer. γ singles, γ-γ coincidence, and γ-α coincidence spectra were also recorded. The absolute intensity of the 327.45-keV γ ray has been determined to be (1.44±0.08)×10-5% per 249Bk decay. Assignments of previously known single-particle states were confirmed. A new rotational band was identified in the α singles spectrum and Am K x rays have been observed in its decay. This single-particle state, with an energy of 154 keV, has been assigned to the 3/2-[521] Nilsson state. This is the lowest excitation energy for this orbital in any Am nucleus. More precise energies and intensities of the 249Bk α groups and γ-ray transitions are provided.

  8. Pulsar Electrons Detection in AMS-02 Experiment. Model Status and Discovery Potential

    NASA Astrophysics Data System (ADS)

    Pochon, Jonathan

    2011-06-01

    The measurements of cosmic rays electrons (e±) have begun a new era a few years ago with high precision experiments like PAMELA and Fermi-LAT. Both experiments show an excess above 10 GeV. Studying Fermi-LAT data, the total electron flux seems to be steeper than expected. While these new measurements have not closed the debate, results from AMS-02 are expected to reach the accuracy needed to determine a full description of these excesses, and hopefully give some evidence on the possible source. We will present in this paper, the AMS-02 capacity in the case of positrons produced by pulsars.

  9. AMS of natural 236U and 239Pu produced in uranium ores

    NASA Astrophysics Data System (ADS)

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

    2007-06-01

    The rare isotopes 236U and 239Pu are produced naturally by neutron capture in uranium ores. Here we measure 236U and 239Pu by accelerator mass spectrometry (AMS) in the same ore samples for the first time. To ensure efficient extraction of both elements and isotopic equilibrium between the 239Pu in the ore and a 242Pu spike, we developed a new sample preparation protocol. AMS has clear advantages over previous methods because it achieves better discrimination against molecular interferences with higher sensitivity and shorter counting times. Measurements of 236U and 239Pu hold considerable promise as proxy indicators of neutron flux and uranium concentration.

  10. Think Big: Leadership Projects for AMS and Montessori Educators

    ERIC Educational Resources Information Center

    Chattin-McNichols, John

    2014-01-01

    The American Montessori Society's (AMS) 2014 Living Legacy recipient, John Chattin-McNichols, delivered the keynote address at the Annual Conference in Dallas, TX, on March 27, 2014, In his speech, he described three overall highlights of AMS: (1) AMS is now a world-leading organization; (2) It must become a learning organization; and (3)…

  11. 47 CFR 73.45 - AM antenna systems.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 4 2013-10-01 2013-10-01 false AM antenna systems. 73.45 Section 73.45... Broadcast Stations § 73.45 AM antenna systems. (a) All applicants for new, additional, or different AM... existing station must specify an antenna system, the efficiency of which complies with the requirements...

  12. 47 CFR 73.45 - AM antenna systems.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false AM antenna systems. 73.45 Section 73.45... Broadcast Stations § 73.45 AM antenna systems. (a) All applicants for new, additional, or different AM... existing station must specify an antenna system, the efficiency of which complies with the requirements...

  13. 47 CFR 73.45 - AM antenna systems.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 4 2011-10-01 2011-10-01 false AM antenna systems. 73.45 Section 73.45... Broadcast Stations § 73.45 AM antenna systems. (a) All applicants for new, additional, or different AM... existing station must specify an antenna system, the efficiency of which complies with the requirements...

  14. 47 CFR 73.45 - AM antenna systems.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 4 2012-10-01 2012-10-01 false AM antenna systems. 73.45 Section 73.45... Broadcast Stations § 73.45 AM antenna systems. (a) All applicants for new, additional, or different AM... existing station must specify an antenna system, the efficiency of which complies with the requirements...

  15. 47 CFR 73.45 - AM antenna systems.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 4 2014-10-01 2014-10-01 false AM antenna systems. 73.45 Section 73.45... Broadcast Stations § 73.45 AM antenna systems. (a) All applicants for new, additional, or different AM... existing station must specify an antenna system, the efficiency of which complies with the requirements...

  16. 30 CFR 75.156 - AMS operator, qualifications.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false AMS operator, qualifications. 75.156 Section 75... HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Qualified and Certified Persons § 75.156 AMS operator, qualifications. (a) To be qualified as an AMS operator, a person shall be provided with...

  17. Challenges of Enterprise Wide AM for Air Force Sustainment

    DTIC Science & Technology

    2016-12-01

    that paradigm will take time and deliberate steps. AM designers will need to be creative , innovative and utilize a new design method- ology that will...ing the Air Force have the necessary AM foundational skills. AM designers will need to be creative , innovative, and utilize a new design methodology

  18. Think Big: Leadership Projects for AMS and Montessori Educators

    ERIC Educational Resources Information Center

    Chattin-McNichols, John

    2014-01-01

    The American Montessori Society's (AMS) 2014 Living Legacy recipient, John Chattin-McNichols, delivered the keynote address at the Annual Conference in Dallas, TX, on March 27, 2014, In his speech, he described three overall highlights of AMS: (1) AMS is now a world-leading organization; (2) It must become a learning organization; and (3)…

  19. 47 CFR 73.49 - AM transmission system fencing requirements.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false AM transmission system fencing requirements. 73.49 Section 73.49 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES RADIO BROADCAST SERVICES AM Broadcast Stations § 73.49 AM transmission system fencing...

  20. 47 CFR 73.49 - AM transmission system fencing requirements.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 4 2013-10-01 2013-10-01 false AM transmission system fencing requirements. 73.49 Section 73.49 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES RADIO BROADCAST SERVICES AM Broadcast Stations § 73.49 AM transmission system fencing...

  1. 47 CFR 73.49 - AM transmission system fencing requirements.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 4 2011-10-01 2011-10-01 false AM transmission system fencing requirements. 73.49 Section 73.49 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES RADIO BROADCAST SERVICES AM Broadcast Stations § 73.49 AM transmission system fencing...

  2. 47 CFR 73.49 - AM transmission system fencing requirements.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 4 2014-10-01 2014-10-01 false AM transmission system fencing requirements. 73.49 Section 73.49 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES RADIO BROADCAST SERVICES AM Broadcast Stations § 73.49 AM transmission system fencing...

  3. 47 CFR 73.49 - AM transmission system fencing requirements.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 4 2012-10-01 2012-10-01 false AM transmission system fencing requirements. 73.49 Section 73.49 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES RADIO BROADCAST SERVICES AM Broadcast Stations § 73.49 AM transmission system fencing...

  4. Technological developments for strontium-90 determination using AMS

    NASA Astrophysics Data System (ADS)

    Satou, Yukihiko; Sueki, Keisuke; Sasa, Kimikazu; Matsunaka, Tetsuya; Takahashi, Tsutomu; Shibayama, Nao; Izumi, Daiki; Kinoshita, Norikazu; Matsuzaki, Hiroyuki

    2015-10-01

    Accelerator mass spectrometry (AMS) is one of method used for 90Sr determination. It would enable rapid 90Sr measurements from environmental samples such as water, soil, and milk. However, routine analysis of 90Sr using AMS has not yet been achieved because of difficulties associated with isobaric separation and production of intense negative ion beams characterized by currents from hundreds of nanoamperes to several microamperes. We have developed a rapid procedure for preparing samples with optimum compositions for use with AMS, which enables production of intense Sr beam currents from an ion source. Samples of SrF2 were prepared from a standard Sr solution and agricultural soil. The time required to prepare a SrF2 sample from a soil sample was 10 h. Negative 88SrF3- ions were successfully extracted at 500 nA from mixed samples of SrF2 and PbF2. In the present work, negative ions of 90Zr, included as an impurity, were accelerated with a tandem accelerator operated at a terminal voltage of 5 MV. Ions characterized by a charge state of 6+ were channeled into a gas counter. An atomic ratio of 90Zr/88Sr of 3 × 10-8 was estimated for the soil sample. No signal was detected from the assay of PbF2, which was pressed in an aluminum cathode, for a mass number of 90. PbF2 revealed good performance in the production of negative SrF3- molecular ion beams and detection of 90Sr with a gas counter.

  5. Detection of fallout 241Am in U.S. Atlantic salt marsh soils

    NASA Astrophysics Data System (ADS)

    Boyd, B. M.; Sommerfield, C. K.

    2017-09-01

    We report the presence of the fallout radionuclide 241Am (t1/2 = 433 years) in salt marsh soils from two U.S. Atlantic estuaries and discuss its utility as a particle tracer and geochronometer. This work is motivated by the knowledge that 137Cs, the most widely used geochronometer in environmental studies, will decay to extinction during the next century. At the same time, levels of 241Am, produced by radioactive decay of fallout 241Pu, will continue to increase on Earth's surface as they have since the height of atmospheric nuclear weapons testing in the 1960s. Measurements of 241Am in soils at eighteen salt marsh locations were made by non-destructive gamma spectrometry and compared to activities of 137Cs in the same samples. Results indicate that decay of fallout 241Pu can explain the presence of 241Am in the soils, and that the activities are sufficiently high to provide meaningful chronological information with acceptable confidence limits. We achieved a detection limit of 0.28-1.47 Bq kg-1 using low-energy, planar germanium detectors and 11-55 g powderized samples. Activities of 241Am (0.08-6.44 Bq kg-1) were similar in mineral- and organic-rich marsh soils indicating that soil composition does not appear to influence the initial capture of 241Pu and retention of its 241Am progeny. Given its high affinity for fine particles, long half-life, and ease of measurement by non-destructive gamma spectrometry, 241Am has potential to serve as an alternative to 137Cs geochronometry in salt marshes and perhaps other estuarine and coastal environments.

  6. A new salicylate synthase AmS is identified for siderophores biosynthesis in Amycolatopsis methanolica 239(T).

    PubMed

    Xie, Feng; Dai, Shengwang; Shen, Jinzhao; Ren, Biao; Huang, Pei; Wang, Qiushui; Liu, Xueting; Zhang, Buchang; Dai, Huanqin; Zhang, Lixin

    2015-07-01

    Siderophores are important for the growth of bacteria or the applications in treatment of iron overload-associated diseases due to the iron-chelating property. Salicylate synthase played a key role in the biosynthesis of some NRPS-derived siderophores by the providing of an iron coordination moiety as the initial building block. A new salicylate synthase, namely AmS, was identified in the biosynthesis pathway of siderophore amychelin in Amycolatopsis methanolica 239(T), since it shunt chorismate, an integrant precursor, from primary to secondary metabolite flow. The amino acid sequence alignment and phylogenetic analysis showed that AmS grouped into a new cluster. In vitro assays of AmS revealed its wide temperature tolerance ranged from 0 to 40 °C and narrow pH tolerant ranged from 7.0 to 9.0. AmS was resistant to organic solvents and non-ionic detergents. Moreover, AmS converted chorismate to salicylate with K m of 129.05 μM, k cat of 2.20 min(-1) at optimal conditions, indicating its low substrate specificity and comparable velocity to reported counterparts (Irp9 and MbtI). These properties of AmS may improve the iron-seizing ability of A. methanolica to compete with its neighbors growing in natural environments. Most importantly, serine and cysteine residues were found to be important for the catalytic activity of AmS. This study presented AmS as a new cluster of salicylate synthase and the reaction mechanism and potential applications of salicylate synthase were highlighted as well.

  7. AMS-02 results support the secondary origin of cosmic ray positrons.

    PubMed

    Blum, Kfir; Katz, Boaz; Waxman, Eli

    2013-11-22

    We show that the recent AMS-02 positron fraction measurement is consistent with a secondary origin for positrons and does not require additional primary sources such as pulsars or dark matter. The measured positron fraction at high energy saturates the previously predicted upper bound for secondary production, obtained by neglecting radiative losses. This coincidence, which will be further tested by upcoming AMS-02 data at higher energy, is a compelling indication for a secondary source. Within the secondary model, the AMS-02 data imply a cosmic ray propagation time in the Galaxy of <10(6) yr and an average traversed interstellar matter density of ~1 cm(-3), comparable to the density of the Milky Way gaseous disk, at a rigidity of 300 GV.

  8. An Interface for the Direct Coupling of Small Liquid Samples to AMS.

    PubMed

    Ognibene, T J; Thomas, A T; Daley, P F; Bench, G; Turteltaub, K W

    2015-10-15

    We describe the moving wire interface attached to the 1-MV AMS system at LLNL's Center for Accelerator Mass Spectrometry for the analysis of nonvolatile liquid samples as either discrete drops or from the direct output of biochemical separatory instrumentation, such as high-performance liquid chromatography. Discrete samples containing at least a few 10s of nanograms of carbon and as little as 50 zmol (14)C can be measured with a 3-5% precision in a few minutes. The dynamic range of our system spans approximately 3 orders in magnitude. Sample to sample memory is minimized by the use of fresh targets for each discrete sample or by minimizing the amount of carbon present in a peak generated by an HPLC containing a significant amount of (14)C. Liquid Sample AMS provides a new technology to expand our biomedical AMS program by enabling the capability to measure low-level biochemicals in extremely small samples that would otherwise be inaccessible.

  9. Development of a fraction collector for coupling gas chromatography with an AMS facility

    NASA Astrophysics Data System (ADS)

    Rottenbach, Andreas; Uhl, T.; Hain, A.; Scharf, A.; Kritzler, K.; Kretschmer, W.

    2008-05-01

    It has been shown that microscale 14C measurements are possible by using a gas handling system and a gas ion source [T. Uhl, W. Kretschmer, W. Luppold, A. Scharf, AMS measurements from microgram to milligram, Nucl. Instr. and Meth. (2005) 474 (240th ed.), T. Uhl, W. Luppold, A. Rottenbach, A. Scharf, K. Kritzler, W. Kretschmer, Development of an automatic gas handling system for microscale AMS (14C) measurements, Nucl. Instr. and Meth. (2007) 303 (259th ed.)]. In Erlangen a gas handling system was especially developed for environmental and biomedical investigations. For the separation of the compound of interest a standard gas chromatograph (GC) is used. To minimize the sample contamination and sample loss we have designed a fraction collector that connects a GC and an elemental analyzer (EA) directly. The selected compound is combusted in the EA and the resulting CO2 is then transferred into the gas handling system for AMS measurements. From the beginning of GC preparation up to the AMS measurement the sample is in a closed line. All operations are fully automated, so no manual operations are necessary. This guarantees high cleanness and maximum sample yield. Preliminary measurements are done using modern and old ethyl alcohol (from fermentation and of petrochemical origin, respectively). The results are consistent with their expected values although cross contamination and background signal increased as the sample mass was decreased.

  10. 21 CFR 822.24 - What are my responsibilities once I am notified that I am required to conduct postmarket...

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... that I am required to conduct postmarket surveillance? 822.24 Section 822.24 Food and Drugs FOOD AND... SURVEILLANCE Responsibilities of Manufacturers § 822.24 What are my responsibilities once I am notified that I am required to conduct postmarket surveillance? You must submit your plan to conduct postmarket...

  11. 21 CFR 822.24 - What are my responsibilities once I am notified that I am required to conduct postmarket...

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... that I am required to conduct postmarket surveillance? 822.24 Section 822.24 Food and Drugs FOOD AND... SURVEILLANCE Responsibilities of Manufacturers § 822.24 What are my responsibilities once I am notified that I am required to conduct postmarket surveillance? You must submit your plan to conduct postmarket...

  12. 21 CFR 822.24 - What are my responsibilities once I am notified that I am required to conduct postmarket...

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... that I am required to conduct postmarket surveillance? 822.24 Section 822.24 Food and Drugs FOOD AND... SURVEILLANCE Responsibilities of Manufacturers § 822.24 What are my responsibilities once I am notified that I am required to conduct postmarket surveillance? You must submit your plan to conduct postmarket...

  13. Rolling-element fatigue life of AMS 5900 balls

    NASA Technical Reports Server (NTRS)

    Parker, R. J.

    1983-01-01

    The rolling-element fatigue life of AMS 5900 12.7-mm (1/2-in.) dia was determined in five-ball fatigue testers. The 10% life with the warm headed AMS 5900 balls was equivalent to that of AMS 5749 and over eight times that of AISI M-50. The AMS balls fabricated by cold heading had small surface cracks which initiated fatigue spalls where these cracks were crossed by running tracks. The cold-headed AMS 5900 balls had a 10% fatigue life an order of magnitude less than that of the warm headed balls even when failures on the cold headed balls at visible surface cracks were omitted.

  14. Educational Opportunities in Pro-Am Collaboration

    NASA Astrophysics Data System (ADS)

    Fienberg, R. T.; Stencel, R. E.

    2006-08-01

    While many backyard stargazers take up the hobby just for fun, many others are attracted to it because of their keen interest in learning more about the universe. The best way to learn science is to do science. Happily, the technology available to today's amateur astronomers — including computer-controlled telescopes, CCD cameras, powerful astronomical software, and the Internet — gives them the potential to make real contributions to scientific research and to help support local educational objectives. Meanwhile, professional astronomers are losing access to small telescopes as funding is shifted to larger projects, including survey programs that will soon discover countless interesting objects needing follow-up observations. Clearly the field is ripe with opportunities for amateurs, professionals, and educators to collaborate. Amateurs will benefit from mentoring by expert professionals, pros will benefit from observations and data processing by increasingly knowledgeable amateurs, and educators will benefit from a larger pool of skilled talent to help them carry out astronomy-education initiatives. We will look at some successful pro-am collaborations that have already borne fruit and examine areas where the need and/or potential for new partnerships is especially large. In keeping with the theme of this special session, we will focus on how pro-am collaborations in astronomy can contribute to science education both inside and outside the classroom, not only for students of school age but also for adults who may not have enjoyed particularly good science education when they were younger. Because nighttime observations with sophisticated equipment are not always possible in formal educational settings, we will also mention other types of pro-am partnerships, including those involving remote observing, data mining, and/or distributed computing.

  15. New Ultraviolet Observations of AM CVn

    NASA Astrophysics Data System (ADS)

    Wade, Richard A.; Eracleous, Michael; Flohic, Hélène M. L. G.

    2007-11-01

    We have obtained observations of the ultraviolet spectrum of AM CVn, an ultrashort-period helium cataclysmic variable, using the Space Telescope Imaging Spectrograph aboard the Hubble Space Telescope (HST). We obtained data in time-tag mode during two consecutive orbits of HST, covering 1600-3150 and 1140-1710 Å, respectively. The mean spectrum is approximately flat in fν. The absorption profiles of the strong lines of N V, Si IV, C IV, He II, and N IV are blueshifted and in some cases asymmetric, evidencing a wind that is partly occulted by the accretion disk. There is weak redshifted emission from N V and He II. The profiles of these lines vary mildly with time. The light curve shows a decline of ~20% over the span of the observations. There is also flickering and a 27 s (or 54 s) "dwarf nova oscillation," revealed in a power-spectrum analysis. The amplitude of this oscillation is larger at shorter wavelengths. We assemble and illustrate the spectral energy distribution of AM CVn from the ultraviolet to the near-infrared. Modeling the accretion phenomenon in this binary system can in principle lead to a robust estimate of the mass accretion rate on to the central white dwarf, which is of great interest in characterizing the evolutionary history of the binary system. Inferences about the mass accretion rate depend strongly on the local radiative properties of the disk, as we illustrate. Uncertainty in the distance of AM CVn and other parameters of the binary system currently limit the ability to confidently infer the mass accretion rate. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. These observations are associated with program 8159.

  16. Separate influences of acoustic AM and FM sensitivity on the phonological decoding skills of impaired and normal readers.

    PubMed

    Witton, Caroline; Stein, John F; Stoodley, Catherine J; Rosner, Burton S; Talcott, Joel B

    2002-08-15

    Developmental dyslexia is associated with deficits in the processing of basic auditory stimuli. Yet it is unclear how these sensory impairments might contribute to poor reading skills. This study better characterizes the relationship between phonological decoding skills, the lack of which is generally accepted to comprise the core deficit in reading disabilities, and auditory sensitivity to amplitude modulation (AM) and frequency modulation (FM). Thirty-eight adult subjects, 17 of whom had a history of developmental dyslexia, completed a battery of psychophysical measures of sensitivity to FM and AM at different modulation rates, along with a measure of pseudoword reading accuracy and standardized assessments of literacy and cognitive skills. The subjects with a history of dyslexia were significantly less sensitive than controls to 2-Hz FM and 20-Hz AM only. The absence of a significant group difference for 2-Hz AM shows that the dyslexics do not have a general deficit in detecting all slow modulations. Thresholds for detecting 2-Hz and 240-Hz FM and 20-Hz AM correlated significantly with pseudoword reading accuracy. After accounting for various cognitive skills, however, multiple regression analyses showed that detection thresholds for both 2-Hz FM and 20-Hz AM were significant and independent predictors of pseudoword reading ability in the entire sample. Thresholds for 2-Hz AM and 240-Hz FM did not explain significant additional variance in pseudoword reading skill. It is therefore possible that certain components of auditory processing of modulations are related to phonological decoding skills, whereas others are not.

  17. The AMS experiment: Results and perspectives

    NASA Astrophysics Data System (ADS)

    Bertucci, B.; AMS Collaboration

    2016-07-01

    The Alpha Magnetic Spectrometer (AMS) experiment operates since May 2011 on board of the International Space Station to search for primordial anti-matter, to study the light anti-matter components in the Cosmic Rays (CR) and to perform a precision study of the CR composition and energy spectrum. More than 60 billion events have been collected by the instrument up to now thanks to its large acceptance and the long exposure time. In this contribution we will discuss the most recent results, reviewing the instrument design and performances as well as the data analysis procedures enabling their achievement.

  18. Changes of AM Fungal Abundance along Environmental Gradients in the Arid and Semi-Arid Grasslands of Northern China

    PubMed Central

    Hu, Yajun; Rillig, Matthias C.; Xiang, Dan; Hao, Zhipeng; Chen, Baodong

    2013-01-01

    Arbuscular mycorrhizal (AM) fungi are ubiquitous symbionts of higher plants in terrestrial ecosystems, while the occurrence of the AM symbiosis is influenced by a complex set of abiotic and biotic factors. To reveal the regional distribution pattern of AM fungi as driven by multiple environmental factors, and to understand the ecological importance of AM fungi in natural ecosystems, we conducted a field investigation on AM fungal abundance along environmental gradients in the arid and semi-arid grasslands of northern China. In addition to plant parameters recorded in situ, soil samples were collected, and soil chemo-physical and biological parameters were measured in the lab. Statistical analyses were performed to reveal the relative contribution of climatic, edaphic and vegetation factors to AM fungal abundance, especially for extraradical hyphal length density (HLD) in the soil. The results indicated that HLD were positively correlated with mean annual temperature (MAT), soil clay content and soil pH, but negatively correlated with both soil organic carbon (SOC) and soil available N. The multiple regressions and structural equation model showed that MAT was the key positive contributor and soil fertility was the key negative contributor to HLD. Furthermore, both the intraradical AM colonization (IMC) and relative abundance of AM fungi, which was quantified by real-time PCR assay, tended to decrease along the increasing SOC content. With regard to the obvious negative correlation between MAT and SOC in the research area, the positive correlation between MAT and HLD implied that AM fungi could potentially mitigate soil carbon losses especially in infertile soils under global warming. However, direct evidence from long-term experiments is still expected to support the AM fungal contribution to soil carbon pools. PMID:23451247

  19. Changes of AM fungal abundance along environmental gradients in the arid and semi-arid grasslands of northern China.

    PubMed

    Hu, Yajun; Rillig, Matthias C; Xiang, Dan; Hao, Zhipeng; Chen, Baodong

    2013-01-01

    Arbuscular mycorrhizal (AM) fungi are ubiquitous symbionts of higher plants in terrestrial ecosystems, while the occurrence of the AM symbiosis is influenced by a complex set of abiotic and biotic factors. To reveal the regional distribution pattern of AM fungi as driven by multiple environmental factors, and to understand the ecological importance of AM fungi in natural ecosystems, we conducted a field investigation on AM fungal abundance along environmental gradients in the arid and semi-arid grasslands of northern China. In addition to plant parameters recorded in situ, soil samples were collected, and soil chemo-physical and biological parameters were measured in the lab. Statistical analyses were performed to reveal the relative contribution of climatic, edaphic and vegetation factors to AM fungal abundance, especially for extraradical hyphal length density (HLD) in the soil. The results indicated that HLD were positively correlated with mean annual temperature (MAT), soil clay content and soil pH, but negatively correlated with both soil organic carbon (SOC) and soil available N. The multiple regressions and structural equation model showed that MAT was the key positive contributor and soil fertility was the key negative contributor to HLD. Furthermore, both the intraradical AM colonization (IMC) and relative abundance of AM fungi, which was quantified by real-time PCR assay, tended to decrease along the increasing SOC content. With regard to the obvious negative correlation between MAT and SOC in the research area, the positive correlation between MAT and HLD implied that AM fungi could potentially mitigate soil carbon losses especially in infertile soils under global warming. However, direct evidence from long-term experiments is still expected to support the AM fungal contribution to soil carbon pools.

  20. Pushing the limits of accelerator mass spectrometry

    NASA Astrophysics Data System (ADS)

    Galindo-Uribarri, A.; Beene, J. R.; Danchev, M.; Doupé, J.; Fuentes, B.; Gomez del Campo, J.; Hausladen, P. A.; Juras, R. C.; Liang, J. F.; Litherland, A. E.; Liu, Y.; Meigs, M. J.; Mills, G. D.; Mueller, P. E.; Padilla-Rodal, E.; Pavan, J.; Sinclair, J. W.; Stracener, D. W.

    2007-06-01

    A renewed interest in Accelerator Mass Spectrometry (AMS) from nuclear physics laboratories is emerging in connection with Radioactive Ion Beams (RIBs). At the Holifield Radioactive Ion Beam Facility (HRIBF) at Oak Ridge National Laboratory (ORNL) we are exploring the AMS capabilities of the 25-MV tandem accelerator. Behind this effort is the realization that two fields of research - AMS and RIBs - complement each other in techniques. Development of effective and efficient beam purification techniques is of common interest to both AMS and the RIB program. Two main characteristics of the 25-MV tandem provide unique opportunities for performing the highest sensitivity measurements of AMS; namely (i) the highest operating voltage in the world, and (ii) a folded geometry which involves a 180° magnet in the terminal. For the RIB program, we have used AMS techniques to improve the sensitivity of detection of some radioactive species in the measurement of unknown masses of n-rich nuclei. For AMS, we have concentrated in exploring two important isotopes, 14C and 36Cl, for applications that require the highest sensitivity. We have successfully measured 36Cl/Cl ratios as low as a few times 10-16 in seawater samples demonstrating that our setup has the highest sensitivity for this isotope and proving that 36Cl can be measured at the levels required for a tracer in oceanography.

  1. Antimicrobial and immunomodulatory properties of PGLa-AM1, CPF-AM1, and magainin-AM1: potent activity against oral pathogens.

    PubMed

    McLean, Denise T F; McCrudden, Maelíosa T C; Linden, Gerard J; Irwin, Christopher R; Conlon, J Michael; Lundy, Fionnuala T

    2014-11-01

    Cationic amphipathic α-helical peptides are intensively studied classes of host defence peptides (HDPs). Three peptides, peptide glycine-leucine-amide (PGLa-AM1), caerulein-precursor fragment (CPF-AM1) and magainin-AM1, originally isolated from norepinephrine-stimulated skin secretions of the African volcano frog Xenopus amieti (Pipidae), were studied for their antimicrobial and immunomodulatory activities against oral and respiratory pathogens. Minimal effective concentrations (MECs), determined by radial diffusion assay, were generally lower than minimal inhibitory concentrations (MICs) determined by microbroth dilution. PGLa-AM1 and CPF-AM1 were particularly active against Streptococcus mutans and all three peptides were effective against Fusobacterium nucleatum, whereas Enterococcus faecalis and Candida albicans proved to be relatively resistant micro-organisms. A type strain of Pseudomonas aeruginosa was shown to be more susceptible than the clinical isolate studied. PGLa-AM1 displayed the greatest propensity to bind lipopolysaccharide (LPS) from Escherichia coli, P. aeruginosa and Porphyromonas gingivalis. All three peptides showed less binding to P. gingivalis LPS than to LPS from the other species studied. Oral fibroblast viability was unaffected by 50 μM peptide treatments. Production of the pro-inflammatory cytokine IL-8 by oral fibroblasts was significantly increased following treatment with 1 or 10 μM magainin-AM1 but not following treatment with PGLa-AM1 or CPF-AM1. In conclusion, as well as possessing potent antimicrobial actions, the X. amieti peptides bound to LPS from three human pathogens and had no effect on oral fibroblast viability. CPF-AM1 and PGLa-AM1 show promise as templates for the design of novel analogues for the treatment of oral and dental diseases associated with bacteria or fungi.

  2. 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

    NASA Astrophysics Data System (ADS)

    Hetmańczyk, Łukasz; Hetmańczyk, Joanna

    2017-02-01

    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.

  3. GLE and the NON-GLE Solar Events Observed by AMS-02 in Solar Cycle 24

    NASA Astrophysics Data System (ADS)

    Bindi, V.; Consolandi, C.; Corti, C.; Whitman, K.

    2014-12-01

    The Alpha Magnetic Spectrometer (AMS-02) is a high energy particle detector installed on the International Space Station (ISS) on May 2011 to study origin and nature of cosmic rays in the energy range from hundreds of MeV to a few TeV. In the first 3 years of operation, AMS-02 measured the highest part of the Solar Energetic Particle (SEP) spectra produced during M-and X-class flares and fast Coronal Mass Ejection. AMS-02 is able to perform precise measurements in a short period of time which is typical of these transient phenomena and to collected enough statistics to fully measure fine structures and time evolution of the spectrum. So far in Solar Cycle 24, one official Ground Level Enhancement (GLE) was observed on May 17, 2012 by Neutron Monitors (NM) while another possible GLE on January 6, 2014 was detected by South Pole NM. Observations by GOES-13, in the high energy proton channels, suggest that there were only 5 SEP events with energies above 500 MeV in this Cycle 24. AMS-02 observations, instead, indicate that since May 2011 there were more than 5 solar events with energies above 500 MeV at Earth. AMS-02 observations, with unprecedented resolution, large acceptance and high statistics, can therefore help the heliophysics community to better understand the true behavior of SEPs at high energies and to constrain models of SEP production. The SEP fluxes of GLE and NON-GLE events observed by AMS-02 will be presented.

  4. Performance in space of the AMS-02 RICH detector

    NASA Astrophysics Data System (ADS)

    Giovacchini, F.

    2014-12-01

    AMS-02 was successfully installed on the International Space Station (ISS) in May 2011, to perform precise measurements of galactic cosmic rays in the 100 MV to few TV magnetic rigidity range. Among several specialized sub-detectors, AMS-02 includes a Ring Imaging Cherenkov detector (RICH), which provides a precise measurement of the particle charge and velocity. The Cherenkov light is produced in a radiator made of silica aerogel and sodium fluoride and collected by means of an array of photomultiplier tubes. Since its launch to space, the detector has been taking data without failures; its functionality and data integrity are monitored and show stable response. In order to achieve the optimal detector performance, calibrations have been performed to account for the dependence of the photodetectors response on temperature and for effective non-uniformities in the detector. The knowledge gathered of the photon yield at the percent level resulted in a charge resolution of 0.3 charge units for He and 0.5 charge units for Si ions. The required precision in the measurements of the particle velocity at the per mil level demanded a more accurate determination of the aerogel refractive index. A map of the aerogel radiator refractive index has been directly inferred from in-flight high statistics data with a precision of Δn / n < 2 ×10-5 on average and its stability with time has also been checked. Finally, a velocity resolution of 0.8 ×10-3 for He and 0.5 ×10-3 for Z > 5 ions has been obtained.

  5. ORFEUS and EUVE observations of AM herculis

    SciTech Connect

    Mauche, C.W.; Paerels, F.B.S.; Raymond, J.C.

    1995-04-06

    Far-UV spectra of AM Her in a high optical state were obtained in 1993 September with the University of California, Berkeley (UCB) spectrometer aboard the ORFEUS telescope. The UCB spectrometer has a spectral resolution {lambda}/{Delta}{lambda} 3000 and covers the 390-1170 {Angstrom} bandpass, but interstellar absorption leaves no detectable -flux below the Lyman limit. Spectra of AM Her were acquired during the intervals 04:19:40-04:36:26 UT on September 16 and 08:34:03-09:09:06 UT on September 17 of 1993. The corresponding magnetic phases are 0.75-0.84 and 0.88-1.07 according to the linear polarization ephemeris of S. Tapia. The main spectral features are the 0 VI doublet, C III {lambda}977, and He II {lambda}1085 (Balmer {gamma}). The bright C III {lambda}1176 multiplet, which is detected by IUE, is at the very end of the spectrum. At the full spectral resolution of the instrument, the 0 VI doublet shows broad and narrow components similar to that of the optical emission lines. The intensity ratio of the narrow component of the 0 VI doublet is {approximately} 1.3:1, much closer to the optically thick limit of 1:1 than the optically thin ratio of 2:1.

  6. Leptophilic dark matter confronts AMS-02 cosmic-ray positron flux

    NASA Astrophysics Data System (ADS)

    Cao, Qing-Hong; Chen, Chuan-Ren; Gong, Ti

    2017-02-01

    With the measurement of positron flux published recently by AMS-02 collaboration, we show how the leptophilic dark matter fits the observation. We obtain the percentages of different products of dark matter annihilation that can best describe the flux of high energy positrons observed by AMS. We show that dark matter annihilates predominantly into $\\tau\\tau$ pair, while both $ee$ and $\\mu\\mu$ final states should be less than $20\\%$. When gauge boson final states are included, the best branching ratio of needed $\\tau\\tau$ mode reduces.

  7. 47 CFR 73.1692 - Broadcast station construction near or installation on an AM broadcast tower.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... the indirect method (see § 73.51). Upon the completion of the installation, antenna impedance... completion of construction, antenna impedance measurements of the AM station shall be made. In addition... simultaneously with the filing of the application for license to cover this permit, the results of the impedance...

  8. 47 CFR 73.1692 - Broadcast station construction near or installation on an AM broadcast tower.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... the indirect method (see § 73.51). Upon the completion of the installation, antenna impedance... completion of construction, antenna impedance measurements of the AM station shall be made. In addition... simultaneously with the filing of the application for license to cover this permit, the results of the impedance...

  9. 47 CFR 73.1692 - Broadcast station construction near or installation on an AM broadcast tower.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... the indirect method (see § 73.51). Upon the completion of the installation, antenna impedance... completion of construction, antenna impedance measurements of the AM station shall be made. In addition... simultaneously with the filing of the application for license to cover this permit, the results of the impedance...

  10. 47 CFR 73.1692 - Broadcast station construction near or installation on an AM broadcast tower.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... the indirect method (see § 73.51). Upon the completion of the installation, antenna impedance... completion of construction, antenna impedance measurements of the AM station shall be made. In addition... simultaneously with the filing of the application for license to cover this permit, the results of the impedance...

  11. 33 CFR 103.505 - Elements of the Area Maritime Security (AMS) Plan.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... ensure the security of the information contained in the AMS Plan; (n) Security measures designed to ensure effective security of infrastructure, special events, vessels, passengers, cargo, and cargo... if a vessel security alert system on board a vessel within or near the port has been activated; (q...

  12. 50 CFR 648.64 - Yellowtail flounder sub-ACLs and AMs for the scallop fishery.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... section: Southern New England Yellowtail Closure Point N. lat. W. long. SNEYT AM 1 41°28.4′ 71°10.25... 2013 fishing years are as follows: (1) 2011. 82 mt for the Southern New England/Mid-Atlantic stock of... yellowtail flounder. (3) 2013. To be determined. (b) Georges Bank accountability measure. (1) Unless...

  13. Determination of 241Am in Urine Using Sector Field Inductively Coupled Plasma Mass Spectrometry (SF-ICP-MS)

    PubMed Central

    Xiao, Ge; Saunders, David; Jones, Robert L.; Caldwell, Kathleen L.

    2016-01-01

    Quantification of 241Am in urine at low levels is important for assessment of individuals’ or populations’ accidental, environmental, or terrorism-related internal contamination, but no convenient, precise method has been established to rapidly determine these low levels. Here we report a new analytical method to measure 241Am as developed and validated at the Centers for Disease Control and Prevention (CDC) by means of the selective retention of Am from urine directly on DGA resin, followed by SF-ICP-MS detection. The method provides rapid results with a Limit of Detection (LOD) of 0.22 pg/L (0.028 Bq/L), which is lower than 1/3 of the C/P CDG for 241Am at 5 days post-exposure. The results obtained by this method closely agree with CDC values as measured by Liquid Scintillation Counting, and with National Institute of Standards Technology (NIST) Certified Reference Materials (CRM) target values. PMID:27375308

  14. Sorption mechanism of Pu, Am and Se on sodium-bentonite

    SciTech Connect

    Shibutani, Tomoki; Yui, Mikazu; Yoshikawa, Hideki

    1994-12-31

    The distribution coefficients (Kd) were measured for Pu, Am and Se on sodium-bentonite in bentonite-equilibrated distilled water in a pH range 4 {approximately} 10. Sodium-bentonite includes sodium-montmorillonite and ferrous minerals such as pyrite. The experiments were carried out by using the batch method under aerobic conditions for Pu, Am and under anaerobic conditions for Se. The distribution coefficients for Pu and Am were in the range 10{sup 0} {approximately} 10{sup 2}m{sup 3}/kg on sodium-bentonite in the above pH range. The sorption of Pu and Am was modeled by ion exchange of these cationic aqueous species with interlayer cations of sodium-bentonite. The distribution coefficients of Se on sodium-bentonite were interpreted by using a surface complexation model. The model was based on the assumption that the sorption behavior was dominated by ferric-oxyhydroxide, goethite, coating on the surface of pyrite. Sorption behavior of Am in compacted bentonite were also discussed by using cation exchange model.

  15. Case Study: Three Acute 241Am Inhalation Exposures with DTPA Therapy

    SciTech Connect

    Carbaugh, Eugene H.; Lynch, Timothy P.; Cannon, Curt; Lewis, Loren L.

    2010-10-01

    Three workers incurred inhalation exposures to 241Am oxide as a result of waste sorting and compaction activities. The magnitudes of the exposures were not fully recognized until the following day when an in vivo chest count identified a significant lung deposition of 241Am in a male worker, and DTPA chelation therapy was initiated. Two additional workers (one female and one male) were then identified as sufficiently exposed to also warrant therapy. In vivo bioassay measurements were performed over the ensuing 6 months to quantify the 241Am activity in the lungs, liver, and skeleton. Urine and fecal samples were collected and showed readily detectable 241Am. Clinical lab tests and medical evaluations all showed normal results. There were no significant adverse clinical health effects from the therapy. The estimated 241Am inhalation intakes for the three workers were 1800 Bq, 630 Bq, and 150 Bq. Lung retention showed somewhat longer pulmonary clearance half-times than standard inhalation class W or absorption Type M assumptions. The three underwent slightly different therapy regimes, with therapy effectiveness factors (defined as the ratio of the reference doses without therapy relative to the final assessed doses) of 4.65, 1.93, and 1.67, respectively.

  16. Unresponsiveness to AmBisome in some Sudanese patients with kala-azar.

    PubMed

    Mueller, Marius; Ritmeijer, Koert; Balasegaram, Manica; Koummuki, Youssif; Santana, Muriel Ramirez; Davidson, Robert

    2007-01-01

    In Sudan, two treatments are currently registered for visceral leishmaniasis: sodium stibogluconate (SSG) as first line and liposomal amphotericin B (AmBisome) as second line. We present 64 patients (52 relapse cases to SSG, 12 new but complicated cases) treated with AmBisome in eastern Sudan. AmBisome was administered at 2.5-8.2mg/kg (15-49mg/kg in total) per dose six times (days 1, 2, 3, 5, 10, 15) as an intravenous infusion. We measured outcome according to clinical response and parasitological clearance (lymph node aspiration). Patient outcomes fell into three groups: group 1, clinical responders (cured) with a negative test of cure (n=35); group 2, clinical responders with a positive test of cure (n=19); group 3, clinical non-responders (failures) with a positive test of cure (n=10). Of the 10 failures, six were already relapse cases. All of group 3, and 15 from group 2, were also treated with additional SSG (20mg/kg intramuscularly daily for 30-50 d) with resulting clinical and parasitological improvement. Parasite persistence and clinical failure were associated with a higher parasite density on admission (P<0.002) and underlying immunosuppressive disease: tuberculosis (three cases) or HIV (two cases). Because AmBisome monotherapy may fail in Sudan, a combination of AmBisome and SSG is recommended for relapse cases.

  17. Up-converted 1/f PM and AM noise in linear HBT amplifiers.

    PubMed

    Ferre-Pikal, Eva S; Savage, Frederick H

    2008-08-01

    In this paper we describe a technique to predict the 1/f phase modulation (PM) and 1/f amplitude modulation (AM) noise due to up-conversion of 1/f baseband current noise in microwave heterojunction bipolar transistor (HBT) amplifiers. We obtain an accurate model for the amplifier and find the expression for voltage gain in terms of DC bias, transistor parameters, and circuit components. Theoretical 1/f PM and AM noise sensitivities to 1/f baseband current noise are then found by applying the definitions of PM and AM noise to the gain expression of the amplifier. Measurements of PM and AM sensitivities at 500 MHz and 1 GHz were in good agreement with the values predicted by theory, verifying the validity of this technique. This method can be used to optimize amplifier design for low PM and AM noise. We show that the amplifier PM noise can be reduced by 9 dB by adjusting the value of the input coupling capacitor.

  18. Amiloride (Am) dissociates human neutrophil (N) activation events

    SciTech Connect

    Berkow, R.L.; Dodson, R.; Kraft, A.S.

    1986-03-05

    Human N can be stimulated to release granule contents and superoxide anion (O/sub 2/sup -//). These events are associated with an Am sensitive Na/sup +//H/sup +/ exchange and N alkalinization. Am has been reported to inhibit protein kinase C (PKC) in HL-60 cells. Due to the central role of PKC in N activation they assessed the effect of prolonged exposure of N to Am. When N were treated with 10/sup -6/ to 10/sup -3/M Am at 37/sup 0/C for 15 min a dose dependent inhibition of O/sub 2/sup -// release was seen upon N stimulation with FMLP (10/sup -6/M), A23187 (10/sup -5/M), or serum treated Zymosan (Z) (2.5 mg/ml). Maximal inhibition depended on the time of exposure of N to Am prior to stimulation and remained after removal of Am by washing. N treated with 10/sup -3/M Am had a decreased influx of /sup 45/Ca/sup + +/ upon stimulation with FMLP. Phorbol myristate acetate induc