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Sample records for cosmogenic 7be produced

  1. Distribution of cosmogenic 7Be in environmental matrices around Kudankulam

    International Nuclear Information System (INIS)

    Selvi, B.S.; George, Thomas; Vijayakumar, B.; Ravi, P.M.

    2014-01-01

    7 Be is a naturally occurring cosmogenic radionuclide produced in the atmosphere through the spallation of nitrogen and oxygen nuclei by cosmic ray produced neutrons and protons. Due to its continuous production in the atmosphere, its relatively short half-life (53.3 days), and its ease of measurement by gamma spectrometry, 7 Be has proven to be a useful tool for tracing and quantifying environmental processes such as atmospheric deposition, atmospheric transport and soil erosion etc. Therefore a systematic study is undertaken to estimate the concentration of 7 Be in different environmental compartments around Kudankulam Nuclear Power Project site. This study discusses the results of the concentration of 7 Be obtained in surface air, dry deposition, rain water and some plant species around Kudankulam Nuclear Power Plant

  2. Cosmogenic radionuclide 7Be in atmospheric fallouts, weather factors and solar activity

    International Nuclear Information System (INIS)

    Kungurov, F.R.

    2011-11-01

    Key words: 7 Be activity, atmospheric fallouts, solar activity, gamma spectroscopy. Subjects of research: cosmogenic radionuclide 7 Be in atmospheric fallouts and surrounding objects of environment, its migrational distribution connected to solar activity and weather meteorologic parameters of the region studied. Purpose of work: Defining correlation between atmospheric humidity and solar activity with concentration and distribution of cosmogenic radionuclide 7 Be. Methods of research: gamma-spectrometry method of activity measurements. The results obtained and their novelty: Cycle of research works on definition of concentration and migrational distribution of CRN 7 Be in Samarkand region during 2002-2005 was carried out for the first time. Volumetric activity of 7 Be in squat air layer of Samarkand was determined. Average density of 7 Be fallouts for the four years of studies was determined. Qualitative correlation bet ween 7 Be fallouts density variations and solar activity, expressed through Wolf number has been found. Qualitative correlation between 7 Be fallouts density variations and amount of precipitations has been found. Regularity in 7 Be concentration decrease towards north latitudes has been detected. Practical value: Developed scintillation method of 7 Be activity detection in atmospheric fallouts was used in works performed in the framework of republican grants 2F-No 1.2.3, CNT RUz PFNI 2F-No 2.1.39 and ITD-7-024. Methodology was used for the estimation of the velocity of erosion processes in the soils of different regions of Uzbekistan. Methodology is used in the works on 7 Be radioactivity measurements. Degree of embed and economic effectivity: Gained results replenish database on 7 Be isotope distribution on Earth regions and its role in formation of some processes, connected with meteorology, agronomy and radioecology of Samarkand region. Field of application: meteorology, agronomy and radioecology. (author)

  3. An introduction to in-situ produced cosmogenic nuclides

    International Nuclear Information System (INIS)

    Norton, K.P.

    2012-01-01

    Cosmogenic nuclides are produced through interactions between cosmic rays and target nuclei in Earth's atmosphere and surface materials. Those which are produced in Earth's atmosphere are termed 'meteoric' while the nuclides produced in surface material are known as in-situ cosmogenic nuclides. The past two decades have seen a proliferation of applications for cosmogenic nuclides. This is primarily due to a revolution in accelerator mass spectrometry, AMS, measurement techniques which has allowed the measurement of very small amounts of nuclides. The following is a brief introduction to the theory and application of in-situ produced cosmogenic nuclide methods. (author). 17 refs., figs., 1 tab.

  4. The cosmogenic radionuclides 7Be, 10Be, and 36Cl in precipitation

    International Nuclear Information System (INIS)

    Knies, D.L.

    1994-01-01

    Two-thirds of atmospheric 7 Be (t 1/2 =53 d), 10 Be(t 1/2 = 1.5 My), and 36 Cl(t 1/2 =0.3 My) is produced in the stratosphere and one-third in the troposphere. The residence time of these radionuclides in the stratosphere is a few years and in the troposphere is a few weeks. Since 7 Be's half-life is short compared to its residence time in the stratosphere and similar to its residence time in the troposphere, the 7 Be/ 10 Be and 7 Be/ 36 Cl ratios should have distinct tropospheric and stratospheric values. Consequently, these isotopes can be used to study processes that involve mixing of air from the troposphere and stratosphere. Relationships between the radionuclide concentrations and air mass history, event type, season, and the major cation and anion concentrations will be presented. Evidence and mechanisms for the fractionation of the 36 Cl and 10 Be concentrations as a function of event type will be presented. Evidence and mechanisms for the fractionation of the 36 Cl and 10 Be concentrations as a function of event type will be presented. A departure from the theoretical 10 Be/ 36 Cl production rate ratio of ∼40 is seen only in one direction with an apparent limit right at the calculated ratio. For this reason, a new theoretical calculation of the 10 Be/ 36 Cl production rate ratio was undertaken. The new calculated value is ∼9.3. This value is in good agreement with the measured mean values in both the Greenland ice sheet and West Lafayette, IN wet precipitation of 8.1 and 9.1 respectively

  5. Cosmogenic production of 7Be and 10Be in the atmosphere

    International Nuclear Information System (INIS)

    O'Brien, K.

    1979-01-01

    Collisions of cosmic-ray particles with nuclei of the air result in the production of energetic secondary nucleons and mesons that in turn collide with other air nuclei to generate a cascade of hadrons through the atmosphere. After its collision with an energetic hadron, the nucleus will be in one or more fragments. Each of these collisions is called a star. About 1.4% of the time, one of the fragments associated with the star will be a 10 Be nucleus, and about 3% of the time, one of the fragments will be 7 Be. The energy spectrum incident on the earth was calculated in the electric field approximation. Ehmert potentials were varied from zero to 1000 MV to encompass the maximum range of solar activity. The geomagnetic field strength was allowed to range from 0.5 to 5 times the current value. The production rates of 7 Be and 10 Be were obtained by calculating the star density as a function of altitude and geomagnetic latitude in the atmosphere. The combined effect of solar modulation and geomagnetic field variation on world-wide star production is shown. The results are in good agreement at each modulation level with the prediction that isotope production should go as Q varies as M - 52 , where M is the geomagnetic field strength given as multiples of the current value. The inventories of these isotopes can be obtained by averaging out the fluctuations produced in the production rate by variations in the solar activity level and the geomagnetic field intensity. This yields 3.5 MCi of Be 10 and 7.7 MCi of Be 7 . 1 figure

  6. A gamma-gamma coincidence/anticoincidence spectrometer for low-level cosmogenic (22)Na/(7)Be activity ratio measurement.

    Science.gov (United States)

    Zhang, Weihua; Ungar, Kurt; Stukel, Matthew; Mekarski, Pawel

    2014-04-01

    In this study, a digital gamma-gamma coincidence/anticoincidence spectrometer was developed and examined for low-level cosmogenic (22)Na and (7)Be in air-filter sample monitoring. The spectrometer consists of two bismuth germanate scintillators (BGO) and an XIA LLC Digital Gamma Finder (DGF)/Pixie-4 software and card package. The spectrometer design allows a more selective measurement of (22)Na with a significant background reduction by gamma-gamma coincidence events processing. Hence, the system provides a more sensitive way to quantify trace amounts of (22)Na than normal high resolution gamma spectrometry providing a critical limit of 3 mBq within a 20 h count. The use of a list-mode data acquisition technique enabled simultaneous determination of (22)Na and (7)Be activity concentrations using a single measurement by coincidence and anticoincidence mode respectively. Copyright © 2014 Elsevier Ltd. All rights reserved.

  7. Quantification of short-term erosion rates using the cosmogenic radionuclide 7Be

    International Nuclear Information System (INIS)

    Jha, Abhinand

    2012-12-01

    The fallout radionuclides 137 Cs, 210 Pb ex are used widely for obtaining quantitative information on soil erosion and sediment redistribution rates within agricultural landscapes, over several spatial and temporal scales, and they are frequently seen to represent a valuable complement to conventional soil erosion measurement techniques. However, measurements of these radionuclides provide estimates of medium term (i.e. 40-100 years) soil erosion rates. The shorter-term perspective provided by the 7 Be method has the potential to estimate soil erosion rates associated with individual events or short periods. The 7 Be method has become increasingly relevant in an environment impacted by climate change, changing land use and other human activities. The present work establishes a mathematical model based on the physical processes of molecular diffusion and radioactive decay, to study the vertical behaviour of 7 Be in soils. This model was further used to quantify erosion rates for 12 individual erosional events over a period of two years at our study site in Muencheberg, Germany. The scope of the model was explored analytically as well as numerically for Pulselike fallout initial condition, zero concentration initial condition and exponential distribution initial condition. The model was fitted to more than 15 depth distributions and the resulting model parameter, effective diffusion coefficient D, is evaluated. In general diffusion coefficients estimated were of the order of 10 -12 -10 -13 m 2 s -1 for loamy to sandy soil types. Diffusion coefficients estimated for our study site were about 10 -13 m 2 s -1 . The soil analyses indicate that the diffusion coefficient D is not merely a fitting parameter, but is related to the physico-chemical properties of radionuclide transport in soils. The erosion rates estimated at tilled and no-till plots at our study site were between -2 and 0.3±0.5 kg m -2 -2.0±1.4 kg m -2 respectively. The magnitude of erosion rates estimated

  8. Quantification of short-term erosion rates using the cosmogenic radionuclide {sup 7}Be

    Energy Technology Data Exchange (ETDEWEB)

    Jha, Abhinand

    2012-12-15

    The fallout radionuclides {sup 137}Cs, {sup 210}Pb{sub ex} are used widely for obtaining quantitative information on soil erosion and sediment redistribution rates within agricultural landscapes, over several spatial and temporal scales, and they are frequently seen to represent a valuable complement to conventional soil erosion measurement techniques. However, measurements of these radionuclides provide estimates of medium term (i.e. 40-100 years) soil erosion rates. The shorter-term perspective provided by the {sup 7}Be method has the potential to estimate soil erosion rates associated with individual events or short periods. The {sup 7}Be method has become increasingly relevant in an environment impacted by climate change, changing land use and other human activities. The present work establishes a mathematical model based on the physical processes of molecular diffusion and radioactive decay, to study the vertical behaviour of {sup 7}Be in soils. This model was further used to quantify erosion rates for 12 individual erosional events over a period of two years at our study site in Muencheberg, Germany. The scope of the model was explored analytically as well as numerically for Pulselike fallout initial condition, zero concentration initial condition and exponential distribution initial condition. The model was fitted to more than 15 depth distributions and the resulting model parameter, effective diffusion coefficient D, is evaluated. In general diffusion coefficients estimated were of the order of 10{sup -12}-10{sup -13} m{sup 2} s{sup -1} for loamy to sandy soil types. Diffusion coefficients estimated for our study site were about 10{sup -13} m{sup 2}s{sup -1}. The soil analyses indicate that the diffusion coefficient D is not merely a fitting parameter, but is related to the physico-chemical properties of radionuclide transport in soils. The erosion rates estimated at tilled and no-till plots at our study site were between <0.001-4.7{+-}0.4 kg m{sup -2} and

  9. Estimating cumulative soil accumulation rates with in situ-produced cosmogenic nuclide depth profiles

    International Nuclear Information System (INIS)

    Phillips, William M.

    2000-01-01

    A numerical model relating spatially averaged rates of cumulative soil accumulation and hillslope erosion to cosmogenic nuclide distribution in depth profiles is presented. Model predictions are compared with cosmogenic 21 Ne and AMS radiocarbon data from soils of the Pajarito Plateau, New Mexico. Rates of soil accumulation and hillslope erosion estimated by cosmogenic 21 Ne are significantly lower than rates indicated by radiocarbon and regional soil-geomorphic studies. The low apparent cosmogenic erosion rates are artifacts of high nuclide inheritance in cumulative soil parent material produced from erosion of old soils on hillslopes. In addition, 21 Ne profiles produced under conditions of rapid accumulation (>0.1 cm/a) are difficult to distinguish from bioturbated soil profiles. Modeling indicates that while 10 Be profiles will share this problem, both bioturbation and anomalous inheritance can be identified with measurement of in situ-produced 14 C

  10. WebCN: A web-based computation tool for in situ-produced cosmogenic nuclides

    Energy Technology Data Exchange (ETDEWEB)

    Ma Xiuzeng [Department of Physics, Purdue University, West Lafayette, IN 47907 (United States)]. E-mail: hongju@purdue.edu; Li Yingkui [Department of Geography, University of Missouri-Columbia, Columbia, MO 65211 (United States); Bourgeois, Mike [Department of Physics, Purdue University, West Lafayette, IN 47907 (United States); Caffee, Marc [Department of Physics, Purdue University, West Lafayette, IN 47907 (United States); Elmore, David [Department of Physics, Purdue University, West Lafayette, IN 47907 (United States); Granger, Darryl [Department of Earth and Atmospheric Sciences, Purdue University, West Lafayette, IN 47907 (United States); Muzikar, Paul [Department of Physics, Purdue University, West Lafayette, IN 47907 (United States); Smith, Preston [Department of Physics, Purdue University, West Lafayette, IN 47907 (United States)

    2007-06-15

    Cosmogenic nuclide techniques are increasingly being utilized in geoscience research. For this it is critical to establish an effective, easily accessible and well defined tool for cosmogenic nuclide computations. We have been developing a web-based tool (WebCN) to calculate surface exposure ages and erosion rates based on the nuclide concentrations measured by the accelerator mass spectrometry. WebCN for {sup 10}Be and {sup 26}Al has been finished and published at http://www.physics.purdue.edu/primelab/for{sub u}sers/rockage.html. WebCN for {sup 36}Cl is under construction. WebCN is designed as a three-tier client/server model and uses the open source PostgreSQL for the database management and PHP for the interface design and calculations. On the client side, an internet browser and Microsoft Access are used as application interfaces to access the system. Open Database Connectivity is used to link PostgreSQL and Microsoft Access. WebCN accounts for both spatial and temporal distributions of the cosmic ray flux to calculate the production rates of in situ-produced cosmogenic nuclides at the Earth's surface.

  11. Validation of cosmogenic nuclide production rate scaling factors through direct measurement. Part 2, Production of 7Be and 10Be in water targets deployed in the Southern Hemisphere, 1997-2001

    International Nuclear Information System (INIS)

    Graham, I.J.; Barry, B.J.; Ditchburn, R.G.; Zondervan, A.

    2005-01-01

    Sealed containers of de-ionised water were exposed to cosmic-rays at seven sites in Australia, New Zealand and Antarctica, covering a range of altitudes and geomagnetic latitudes, over time periods of six months to three years (1997-2001). After isotopic analysis by gamma counting (for 7 Be) and accelerator mass spectrometry (for 10 Be), the data obtained were corrected to obtain relative production factors (i.e., 'k' values). This report presents a full description of the target design, isotope extraction, and measurement procedures employed. It thus provides the raw data from which cosmogenic nuclide production rates for the Southern Hemisphere can be calculated, and scaling factors used in surface exposure dating can be independently validated. (author). 35 refs., 7 figs., 5 tabs

  12. New approaches investigating production rates of in-situ produced terrestrial cosmogenic nuclides

    Energy Technology Data Exchange (ETDEWEB)

    Merchel, Silke [CEREGE, CNRS-IRD-Universite Aix-Marseille, Aix-en-Provence (France); FZD, Dresden (Germany); Braucher, Regis; Benedetti, Lucilla; Bourles, Didier [CEREGE, CNRS-IRD-Universite Aix-Marseille, Aix-en-Provence (France)

    2010-07-01

    In-situ produced cosmogenic nuclides have proved to be valuable tools for environmental and Earth sciences. However, accurate application of this method is only possible, if terrestrial production rates in a certain environment over a certain time period and their depth-dependence within the exposed material are exactly known. Unfortunately, the existing data and models differ up to several tens of percent. Thus, one of the European project CRONUS-EU goals is the high quality calibration of the {sup 36}Cl production rate by spallation at independently dated surfaces. As part of fulfilling this task we have investigated calcite-rich samples from four medieval landslide areas in the Alps: Mont Granier, Le Claps, Dobratsch, and Veliki Vrh (330-1620 m, 1248-1442 AD). For investigating the depth-dependence of the different nuclear reactions, especially, the muon- and thermal neutron-induced contributions, we have analysed mixtures of carbonates and siliceous conglomerate samples - for {sup 10}Be, {sup 26}Al, and {sup 36}Cl - exposed at different shielding depths and taken from a core drilled in 2005 at La Ciotat, France (from surface to 11 m shielding). AMS of {sup 36}Cl was performed at LLNL and ETH, {sup 10}Be and {sup 26}Al at ASTER.

  13. Studies in earth sciences using in-situ produced cosmogenic radioisotopes

    International Nuclear Information System (INIS)

    Fink, D.

    1998-01-01

    The geological processes of glaciation and surface weathering which have moulded and continue to shape our landscape, are inextricably related to the dynamics of climate change. Earth Scientists have long sought an analytical technique based on radiometric methods that would quantify both temporally and spatially, the chronology of glacial cycles and erosion rates. Such a technique is now developing based on the in-situ production by cosmic rays of the long-lived cosmogenic radionuclides 10 Be (T 1 / 2 =1.5 Ma), 26 Al (0.7 Ma) and 36 Cl (0.3a) in exposed rocks, surfaces and within the first meter or so of the Earth's crust. Although only a million atoms of 10 Be are produced during a 100 ka exposure period per gram of rock, AMS can be applied to measure this telltale signal. Their build-up over time can be utilised as radiometric clocks to elucidate the exposure history of geomorphic formations and surfaces. Alternatively, if exposure has been sufficiently long for the in-situ signal to reach equilibrium, an average erosion rate can be determined. The applicability of the technique depends on the radioisotope half-life - in simple terms it works best over exposure periods of 5ka to 5 Ma (for 10 Be) and can identify erosion rates from 0.1 to 10 mm/ka

  14. Methodological study on exposure date of Tiankeng by AMS measurement of in situ produced cosmogenic {sup 36}Cl

    Energy Technology Data Exchange (ETDEWEB)

    Dong Kejun [China Institute of Atomic Energy, P.O. Box 275(50), Beijing 102413 (China); Li Shizhuo [China Institute of Atomic Energy, P.O. Box 275(50), Beijing 102413 (China); CNNC China North Nuclear Fuel Company Ltd., Baotou 014035 (China); He Ming [China Institute of Atomic Energy, P.O. Box 275(50), Beijing 102413 (China); Sasa, Kimikazu [Tandem Accelerator Complex, University of Tsukuba, Tsukuba, Ibaraki 305-8577 (Japan); Matsushi, Yuki [Disaster Prevention Research Institute, Kyoto University (Japan); Huang Baojian [Institute of Karst Geology, Chinese Academy of Geological Sciences, Guilin 541004 (China); Ruan Xiangdong; Guan Yongjing [College of Physics Science and Technology, Guangxi University, Nanning 530004 (China); Takahashi, Tsutomu [Tandem Accelerator Complex, University of Tsukuba, Tsukuba, Ibaraki 305-8577 (Japan); Sueki, Keisuke [Graduate School of Pure and Applied Sciences, University of Tsukuba (Japan); Li Chaoli; Wu Shaoyong [China Institute of Atomic Energy, P.O. Box 275(50), Beijing 102413 (China); Wang Xianggao [China Institute of Atomic Energy, P.O. Box 275(50), Beijing 102413 (China); Institute of Karst Geology, Chinese Academy of Geological Sciences, Guilin 541004 (China); Shen Hongtao [China Institute of Atomic Energy, P.O. Box 275(50), Beijing 102413 (China); College of Physics and Technology, Guangxi Normal University, Guilin 541004 (China); Nagashima, Yasuo [Tandem Accelerator Complex, University of Tsukuba, Tsukuba, Ibaraki 305-8577 (Japan); Jiang Shan, E-mail: jiangs@ciae.ac.cn [China Institute of Atomic Energy, P.O. Box 275(50), Beijing 102413 (China)

    2013-01-15

    Tiankeng is a typical Karst relief of the late Quaternary Period. Studies on the exposure ages of Tiankeng are very important in geographical research to elucidate the formation condition, the developing process, and the features of biological species. {sup 36}Cl on the surface layer of the rupture cross-section of Tiankeng is largely produced by cosmogenic high-energy neutron induced reactions {sup 40}Ca(n, {alpha}p) and {sup 39}K(n, {alpha}), and has accumulated since the formation of the Tiankeng. Low-energy neutron reaction {sup 35}Cl(n, {gamma}) contributes a small portion of {sup 36}Cl. In this work, the concentration of the cosmogenic {sup 36}Cl in rock samples taken from Dashiwei Tiankeng, Leye County, Guangxi Zhuang Autonomous Region, China, was measured jointly by Accelerator Mass Spectrometry (AMS) laboratories of CIAE and University of Tsukuba in an effort to estimate the formation time (or exposure age) of the Tiankeng. The results show that the exposure time of Da Shiwei Tiankeng is about 26 {+-} 9.6 ka (without erosion correction). The sampling strategy and procedures, experimental set-up, and preliminary results will be presented in detail.

  15. Cosmic ray exposure dating with in situ produced cosmogenic 3He: results from young Hawaiian lava flows

    Science.gov (United States)

    Kurz, M.D.; Colodner, D.; Trull, T.W.; Moore, R.B.; O'Brien, K.

    1990-01-01

    In an effort to determine the in situ production rate of spallation-produced cosmogenic 3He, and evaluate its use as a surface exposure chronometer, we have measured cosmogenic helium contents in a suite of Hawaiian radiocarbon-dated lava flows. The lava flows, ranging in age from 600 to 13,000 years, were collected from Hualalai and Mauna Loa volcanoes on the island of Hawaii. Because cosmic ray surface-exposure dating requires the complete absence of erosion or soil cover, these lava flows were selected specifically for this purpose. The 3He production rate, measured within olivine phenocrysts, was found to vary significantly, ranging from 47 to 150 atoms g-1 yr-1 (normalized to sea level). Although there is considerable scatter in the data, the samples younger than 10,000 years are well-preserved and exposed, and the production rate variations are therefore not related to erosion or soil cover. Data averaged over the past 2000 years indicate a sea-level 3He production rate of 125 ?? 30 atoms g-1 yr-1, which agrees well with previous estimates. The longer record suggests a minimum in sea level normalized 3He production rate between 2000 and 7000 years (55 ?? 15 atoms g-1 yr-1), as compared to samples younger than 2000 years (125 ?? 30 atoms g-1 yr-1), and those between 7000 and 10,000 years (127 ?? 19 atoms g-1 yr-1). The minimum in production rate is similar in age to that which would be produced by variations in geomagnetic field strength, as indicated by archeomagnetic data. However, the production rate variations (a factor of 2.3 ?? 0.8) are poorly determined due to the large uncertainties in the youngest samples and questions of surface preservation for the older samples. Calculations using the atmospheric production model of O'Brien (1979) [35], and the method of Lal and Peters (1967) [11], predict smaller production rate variations for similar variation in dipole moment (a factor of 1.15-1.65). Because the production rate variations, archeomagnetic data

  16. Cosmogenically-produced isotopes in natural and enriched high-purity germanium detectors for the MAJORANA DEMONSTRATOR

    Science.gov (United States)

    Gilliss, Thomas; MAJORANA DEMONSTRATOR Collaboration

    2017-01-01

    The MAJORANA DEMONSTRATOR advances toward measurements of the neutrinoless double-beta decay of 76Ge. Detectors employed in the DEMONSTRATOR are subject to cosmogenic spallation during production and processing, resulting in activation of certain long-lived radioisotopes. Activation of these cosmogenic isotopes is mitigated by shielded storage of detectors and through underground operation of the DEMONSTRATOR at the 4850 ft level of the Sanford Underground Research Facility. In this work, we explore the appearance and reduction of cosmogenic contributions to the DEMONSTRATOR background spectrum. This work is supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, the Particle Astrophysics and Nuclear Physics Programs of the National Science Foundation, and the Sanford Underground Research Facility.

  17. Evaluation of 7Be fallout spatial variability

    International Nuclear Information System (INIS)

    Pinto, Victor Meriguetti

    2011-01-01

    The cosmogenic radionuclide beryllium-7 (Be) is produced in the atmosphere by cosmic particle reactions and is being used as a tracer for soil erosion and climatic processes research. After the production, 7 Be bonds to aerosol particles in the atmosphere and is deposited on the soil surface with other radionuclide species by rainfall. Because of the high adsorption on soil particles and its short half-life of 53.2 days, this radionuclide follows of the erosion process and can be used as a tracer to evaluate the sediment transport that occurs during a single rain event or short period of rain events. A key assumption for the erosion evaluation through this radiotracer is the uniformity of the spatial distribution of the 7 Be fallout. The 7 Be method was elaborated recently and due to its few applications, some assumptions related to the method were not yet properly investigated yet, and the hypothesis of 7 Be fallout uniformity needs to be evaluated. The aim of this study was to evaluate the 7 Be fallout spatial distribution through the rain water 7 Be activity analysis of the first five millimeters of single rain events. The rain water was sampled using twelve collectors distributed on an experimental area of about 300 m2 , located in the campus of Sao Paulo University, Piracicaba. The 7 Be activities were measured using a 53% efficiency gamma-ray spectrometer from the Radioisotope laboratory of CENA. The 7 Be activities in rain water varied from 0.26 to 1.81 Sq.L - 1, with the highest values in summer and lowest in spring. In each one of the 5 single events, the spatial variability of 7 Se activity in rain water was high, showing the high randomness of the fallout spatial distribution. A simulation using the 7 Be spatial variability values obtained here and 7 Se average reference inventories taken from the literature was performed determining the lowest detectable erosion rate estimated by 7 Be model. The importance of taking a representative number of samples to

  18. Study of a neutron producing target via the 7Li(p,n)7Be reaction near its energy threshold for BNCT (boron neutron capture therapy)

    International Nuclear Information System (INIS)

    Burlon, Alejandro; Kreiner, Andres J.; Debray, Mario E.; Stoliar, Pablo; Kesque, Jose M.; Naab, Fabian; Ozafran, Mabel J.; Schuff, Juan; Vazquez, Monica; Caraballo, Maria E.; Valda, Alejandro; Somacal, Hector; Davidson, Miguel; Davidson, Jorge

    2000-01-01

    In the framework of Accelerator Based BNCT (AB-BNCT) the 7 Li(p,n) 7 Be reaction near its energy threshold is one of the most promising. In this work a thick LiF target irradiated with a proton beam was studied as a neutron source. The 1.88-2.0 MeV proton beam was produced by the tandem accelerator TANDAR at CNEA's facilities in Buenos Aires. A water-filled phantom, containing a boron sample was irradiated with the resulting neutron beam. The boron neutron capture reaction produces a 0.478 MeV gamma ray in 94 % of the cases. The neutron yield was monitored by detecting this gamma ray using a germanium detector with an 'anti-Compton' shield. Moreover, the thermal neutron flux was evaluated at different depths inside the phantom using bare and Cd-covered gold foils. A maximum neutron thermal flux of 1.4 x 10 8 1/(cm 2 -s-mA) was obtained at 4.2 cm from the phantom surface. (author)

  19. Denudation rates of the Southern Espinhaço Range, Minas Gerais, Brazil, determined by in situ-produced cosmogenic beryllium-10

    Science.gov (United States)

    Barreto, Helen N.; Varajão, César A. C.; Braucher, Régis; Bourlès, Didier L.; Salgado, André A. R.; Varajão, Angélica F. D. C.

    2013-06-01

    To investigate denudation rates in the southern part of the Espinhaço Range (central-eastern Brazil) and to understand how this important resistant and residual relief has evolved in the past 1.38 My, cosmogenic 10Be concentrations produced in situ were measured in alluvial sediments from the three main regional basins, whose substratum is composed primarily of quartzites. The long-term denudation rates (up to 1.38 My) estimated from these measurements were compared with those that affect the western (São Francisco River) and eastern (Doce and Jequitinhonha Rivers) basins, which face the West San Francisco craton and the Atlantic, respectively. Denudation rates were measured in 27 samples collected in catchments of different sizes (6-970 km2) and were compared with geomorphic parameters. The mean denudation rates determined in the northern part are low and similar to those determined in the southern part, despite slightly different geomorphic parameter values (catchment relief and mean slope). For the southern catchments, the values are 4.91 ± 1.01 m My- 1 and 3.65 ± 1.26 m My- 1 for the Doce and São Francisco River basins, respectively; for the northern catchments, they are 4.40 ± 1.06 m My- 1 and 3.96 ± 0.91 m My- 1 for the Jequitinhonha and São Francisco River basins, respectively. These low values of denudation rates suggest no direct correlation if plotted against geomorphic parameters such as the catchment area, maximum elevation, catchment relief, average relief and mean slope gradients. These values show that the regional landscape evolves slowly and is strongly controlled by resistant lithology, with similar erosional rates in the three studied basins.

  20. High performance liquid chromatographic separation of beryllium from some transition metals produced in high energy proton irradiations of medium mass elements: measurement of (p,7Be) cross sections

    International Nuclear Information System (INIS)

    Fassbender, M.; Spellerberg, S.; Qaim, S.M.

    1996-01-01

    A high performance liquid chromatographic (HPLC) method was developed for the separation of 7 Be formed in high energy proton irradiation of medium mass elements like Fe, Cu etc. The bulk of the target material was removed in a preseparation step. Thereafter beryllium was obtained in a high purity within a few minutes elution time using a mixture of 5 mM citric acid and 1.0 mM pyridinedicarboxylic acid as eluent and a SYKAM KO2 analytical cation-exchange column. The effect of Be-carrier on the quality of separation was investigated. The quality of separation deteriorated with the increasing Be-carrier column loading. A certain amount of Be-carrier was, however, necessary in order to quantitate the results. By using low Be-carrier amounts (∝100 μg) and determining the elution yield via a conductometric method, it was possible to obtain quantitative separation results. Besides the analytical column, a semi-preparative column was also used, and the Be separation yield determined gravimetrically. The cross sections for the (p, 7 Be) process on Cu obtained using the two separation columns (analytical and semipreparative) and the two separation yield determination methods agreed within 15%. (orig.)

  1. Cosmogenic isotope beryllium-7 in the atmosphere: Production versus transport

    Science.gov (United States)

    Pacini, Alessandra; Usoskin, Ilya; Evangelista, Heitor; Echer, Ezequiel; Mursula, Kalevi; Leppanen, Ari-Pekka

    Cosmogenic isotope 7 Be measured near the ground can provide information about its produc-tion (that occurs in the atmosphere due to the interaction of cosmic rays and atmospheric constituents) and its deposition processes (that involves air mass dynamics, stratosphere-troposphere coupling and local climatic conditions). We present the results of an investigation of the atmospheric 7 Be temporal variations at different geographic locations (Finland and Brazil). This study was based on an analysis of three time series of 7 Be concentration measured in near-surface air samples from Rovaniemi and Loviisa (Finland) and Rio de Janeiro (Brazil) for the last decades. We made use of the wavelet spectral method to identify the frequency-temporal features of the 7 Be temporal variations that allowed us to determine the relative importance of production and deposition process for the observed data. By comparing these time series with climatic indices and the values of 7 Be concentration expected from the model for the same period, we found that the climate system is the main driver of the surface isotopic modulation, while the imprints of the production variations are geographically dependent. Thus,7 Be can be considered a good tool to monitor the large-scale air mass dynamics.

  2. Cosmogenic Radionuclides in the Atmosphere: Origin and Applications

    International Nuclear Information System (INIS)

    Abdel Monem, A.A.

    2013-01-01

    The primary cosmic radiation arriving at the top of the atmosphere comprise mainly positively charged particles: protons (∼87%), alpha -particles (∼12%) and heavier nuclei such as Li, Be, B, C, O and F. Their energy spectrum peaks are in the vicinity of 1-2 GeV, but may extend up to 1018 eV. They are believed to be of galactic origin and to have been accelerated to their present energies by inters teller magnetic fields. The low energy particles ionize the atmosphere and are stopped. All other particles undergo collision with the nuclei of the atmosphere gases and produce new particles by a fragmentation process called s pallation . During nuclear spallation reactions in the atmosphere, particles are produced which may be either fragments of the target nucleus or newly created by collision. The particles produced are nuclei of H and He particularly 2 H, 3 H and 3 He as well as neutrons. The neutrons that are involved in these processes are captured by 14 N to produce 14 C (t 1/2 =5730 y). Also, produced by interaction with atmospheric N are: 3 H, 3 He, 7 Be and 10 Be. All these nuclides can also be formed by interaction with O as well as 14 C. Interaction with 40 Ar produces 26 AI, 36 CI, 38 CI, 39 CI, 32 Si, 37 Ar, 39 Ar, 22 Na, 24 Na, 35 S, 33 P and 32 P. Interaction with Kr produces 81 Kr and 85 Kr. With the exception of 3 He, all these nuclides are unstable. They either remain in the atmosphere for substantial periods of time or are rapidly removed by precipitation. Several of the cosmogenic radionuclides have reasonable long half-lives to be useful for the study of geological processes. The cosmogenic 14 C forms 14 CO 2 which is rapidly mixed with the atmosphere. Living organisms contain constant level 14 C, but when dead, the activity due to 14 C decreases with a half-life of 5730 y. Hence, it can be used to measure ages of C- containing materials. Tritium (t 1/2 =12.33 y) in the atmosphere is removed with the meteoric precipitation, which under favorable

  3. Cosmogenic activation of materials

    Science.gov (United States)

    Cebrián, Susana

    2017-10-01

    Experiments looking for rare events like the direct detection of dark matter particles, neutrino interactions or the nuclear double beta decay are operated deep underground to suppress the effect of cosmic rays. But, the production of radioactive isotopes in materials due to previous exposure to cosmic rays is a hazard when ultra-low background conditions are required. In this context, the generation of long-lived products by cosmic nucleons has been studied for many detector media and for other materials commonly used. Here, the main results obtained on the quantification of activation yields on the Earth’s surface will be summarized, considering both measurements and calculations following different approaches. The isotope production cross-sections and the cosmic ray spectrum are the two main ingredients when calculating this cosmogenic activation; the different alternatives for implementing them will be discussed. Activation that can take place deep underground mainly due to cosmic muons will be briefly commented too. Presently, the experimental results for the cosmogenic production of radioisotopes are scarce and discrepancies between different calculations are important in many cases, but the increasing interest on this background source which is becoming more and more relevant can help to change this situation.

  4. Estimation of site specific deposition velocities and mass interception factor using 7Be as a tracer in Kudankulam environment

    International Nuclear Information System (INIS)

    Selvi, B.S.; Vijayakumar, B.; Ravi, P.M.

    2018-01-01

    Beryllium-7 ( 7 Be) is a cosmogenic radionuclide formed in the atmosphere when cosmic ray produced neutrons and protons disintegrate the atomic nucleus of nitrogen and oxygen in to lighter fragments. ' 7 Be is found naturally in air, rainwater, vegetation, soils and sediments as well as lake and ocean waters. Due to its continuous production in the atmosphere, its relatively short half-life (53.3 days), and its ease of measurement by gamma spectrometry, 7 Be has proven to be a useful tool for tracing and quantifying environmental processes such as atmospheric deposition, atmospheric transport and soil erosion etc. A systematic study is carried out to estimate the site specific deposition velocities and the mass interception factor around the Kudankulam environment

  5. Determination of 7BE in soil sample by gamma spectrometry for erosion researchs

    International Nuclear Information System (INIS)

    Esquivel, Alexander D.; Kastner, Geraldo F.; Amaral, Angela M.; Monteiro, Roberto Pellacani G.; Moreira, Rubens M.

    2015-01-01

    Cosmogenic 7 Be is a natural radiotracer produced in the stratosphere and troposphere and reached to the Earth surface via wet and dry fallout and hence its measurement for research of erosion in soils is very significant. The 7 Be radio analyse based on gamma spectrometry technique has been a routine methodology for decades and although is the reference procedure is not free of analytical interference. 7 Be is a β-γ emitting radionuclide (Eγ = 477.59 keV, T½ = 53.12d) and depending on the chemical profile of the soil its determination is susceptible to 228 Ac (E γ = 478.40 keV, T½ = 6.15h) interference. The aim of this work was to establish an analytical protocol for the 7 Be determination in soil samples from Juatuba-Mg region in different sampling periods of dry and rainy seasons for erosion studies and to establish some methodologies for evaluating and correcting the interference level of 228 Ac in the 7 Be activity measurements by gamma spectrometry. (author)

  6. Cosmogenic 3He in detrital gold

    Science.gov (United States)

    Stuart, Finlay; Yakubovich, Olga; Caracedo, Ana; Nesterenok, Alexander

    2017-04-01

    Since the measurement of cosmogenic He in an alluvial diamond by McConville and Reynolds (1996) the application of cosmogenic noble gases to individual detrital grains to quantify surface processes has not been vigorously pursued. The likely low rate of diffusion of cosmogenic He in native metals, and their resistance to weathering and disintegration during erosion and transport, makes them a potential record of long-term Earth surface processes. In an effort to assess the extent that detrital refractory metals record the exposure history during transport and storage we have undertaken a reconnaissance study of the He isotope composition in 18 grains (2-200 mg) of native gold, copper, silver, and PtPd, Pt3Fe and OsIr alloys from alluvial placer deposits from around the world. 4He is dominantly the result of U and Th decay within the grains, or decay of 190Pt in the Pt-rich alloys. 3He is measurable in 13 grains, concentrations range up to 2.7E+6 atoms/g. 3He/4He are always in excess of the crustal radiogenic ratio, up to 306 Ra. Although nucleogenic 3He produced by (n,α) reactions on 6Li, and 3He from trapped hydrothermal fluids, are present, the majority of the 3He is cosmogenic in origin. Using newly calculated cosmogenic 3He production rates in heavy metals, and a determination of the effect of implantation based on the stopping distances of spallogenic 3He and 3H, the grains have 3Hecos concentrations that are equivalent to 0.35 to 1.5 Ma exposure at Earth's surface. In a study of detrital gold grains from several sites in Scotland we have found that 10 % have 3He concentrations that are significantly in excess of that generated since the Last Glacial Maximum. These studies demonstrate that, with refinement, cosmogenic 3He in refractory detrital minerals can be used to quantify sediment transport and storage on the 1-10 Ma timescale. P. McConville & J.H. Reynolds (1989). Geochim. Cosmochim. Acta, 53, 2365-75.

  7. 7Li--7Be experiment

    International Nuclear Information System (INIS)

    Rowley, J.K.

    1978-01-01

    An experiment to detect solar neutrinos by use of lithium is considered. The reaction employed is 7 Li(ν,e - ) 7 Be. The parameters of a possible experimental arrangement are described; chemical separation, backgrounds, and counting are discussed at some length. Despite the problems such an experiment still seems feasible. 5 figures, 6 tables

  8. Lithogenic and cosmogenic tracers in catchment hydrology

    Energy Technology Data Exchange (ETDEWEB)

    Nimz, G.J.

    1995-01-01

    A variety of physical processes affect solute concentrations within catchment waters. The isotopic compositions of the solutes can indicate which processes have determined the observed concentrations. These processes together constitute the physical history of the water, which is one of the primary concerns in hydrology. Many groundwater solutes are derived as a result of interaction between the water and the rock and/or soil within the system. These are termed {open_quotes}lithogenic{close_quotes} solutes. The isotopic compositions of these solutes provide information regarding rock-water interactions. Many other solutes have their isotopic compositions determined both internally and externally to the catchment system. Important members of this group include solutes that have isotopic compositions produced by atomic particle interactions with other nuclides. The source of the atomic particles can be cosmic radiation (producing {open_quotes}cosmogenic{close_quotes} nuclides in the atmosphere and land surface), anthropogenic nuclear reactions (producing {open_quotes}thermonuclear{close_quotes} nuclides), or radioactive and fission decay of naturally-occurring elements, such as U and Th (producing {open_quotes}in-situ{close_quotes} lithogenic nuclides in the deep subsurface). Current language usage often combines all of the atomic particle-produced nuclides under the heading {open_quotes}cosmogenic nuclides{close_quotes}, and for simplicity we will often follow that usage, although always clearly indicating which variety is being discussed. This paper addresses the processes that affect the lithogenic and cosmogenic solute compositions in groundwater, and how these compositions can therefore be used in integrative ways to understand the physical history of groundwater within a catchment system.

  9. Lithogenic and cosmogenic tracers in catchment hydrology

    International Nuclear Information System (INIS)

    Nimz, G.J.

    1995-01-01

    A variety of physical processes affect solute concentrations within catchment waters. The isotopic compositions of the solutes can indicate which processes have determined the observed concentrations. These processes together constitute the physical history of the water, which is one of the primary concerns in hydrology. Many groundwater solutes are derived as a result of interaction between the water and the rock and/or soil within the system. These are termed open-quotes lithogenicclose quotes solutes. The isotopic compositions of these solutes provide information regarding rock-water interactions. Many other solutes have their isotopic compositions determined both internally and externally to the catchment system. Important members of this group include solutes that have isotopic compositions produced by atomic particle interactions with other nuclides. The source of the atomic particles can be cosmic radiation (producing open-quotes cosmogenicclose quotes nuclides in the atmosphere and land surface), anthropogenic nuclear reactions (producing open-quotes thermonuclearclose quotes nuclides), or radioactive and fission decay of naturally-occurring elements, such as U and Th (producing open-quotes in-situclose quotes lithogenic nuclides in the deep subsurface). Current language usage often combines all of the atomic particle-produced nuclides under the heading open-quotes cosmogenic nuclidesclose quotes, and for simplicity we will often follow that usage, although always clearly indicating which variety is being discussed. This paper addresses the processes that affect the lithogenic and cosmogenic solute compositions in groundwater, and how these compositions can therefore be used in integrative ways to understand the physical history of groundwater within a catchment system

  10. Cosmogenic radionuclides as a synchronisation tool - present status

    Science.gov (United States)

    Muscheler, Raimund; Adolphi, Florian; Mekhaldi, Florian; Mellström, Anette; Svensson, Anders; Aldahan, Ala; Possnert, Göran

    2014-05-01

    Changes in the flux of galactic cosmic rays into Earth's atmosphere produce variations in the production rates of cosmogenic radionuclides. The resulting globally synchronous signal in cosmogenic radionuclide records can be used to compare time scales and synchronise climate records. The most prominent example is the 14C wiggle match dating approach where variations in the atmospheric 14C concentration are used to match climate records and the tree-ring based part of the 14C calibration record. This approach can be extended to other cosmogenic radionuclide records such as 10Be time series provided that the different geochemical behaviour of 10Be and 14C is taken into account. Here we will present some recent results that illustrate the potential of using cosmogenic radionuclide records for comparing and synchronising different time scales. The focus will be on the last 50000 years where we will show examples how geomagnetic field, solar activity and unusual short-term cosmic ray changes can be used for comparing ice core, tree ring and sediment time scales. We will discuss some unexpected offsets between Greenland ice core and 14C time scale and we will examine how far back in time solar induced 10Be and 14C variations presently can be used to reliably synchronise ice core and 14C time scales.

  11. Validation of cosmogenic nuclide production rate scaling factors through direct measurement

    Energy Technology Data Exchange (ETDEWEB)

    Graham, I.J. E-mail: i.graham@gns.cri.nz; Barry, B.J.; Ditchburn, R.G.; Whitehead, N.E

    2000-10-01

    {sup 7}Be produced in water targets by nuclear interactions of cosmic rays has been measured to determine cosmogenic nuclide production rates as a function of altitude (sea level to 2 km) and geomagnetic latitude (20-79 deg. S). Relative intensities of low energy cosmic ray neutrons have at the same time been measured using neutron monitors based on IGY/NM-64 designed to efficiently thermalise ca. 2-30 MeV neutrons. The research is on-going and we present here preliminary data from the past two years. Water target and neutron flux results are in general agreement, and are consistent with the altitude-dependent scaling factors of Lal [Earth Planet. Sci. Lett. 104 (1991) 4241]. Significant differences between the sea level, latitude-dependent neutron flux data and Lal's predictions are possibly related to the response function of the detector.

  12. Validation of cosmogenic nuclide production rate scaling factors through direct measurement

    CERN Document Server

    Graham, I J; Ditchburn, R G; Whitehead, N E

    2000-01-01

    sup 7 Be produced in water targets by nuclear interactions of cosmic rays has been measured to determine cosmogenic nuclide production rates as a function of altitude (sea level to 2 km) and geomagnetic latitude (20-79 deg. S). Relative intensities of low energy cosmic ray neutrons have at the same time been measured using neutron monitors based on IGY/NM-64 designed to efficiently thermalise ca. 2-30 MeV neutrons. The research is on-going and we present here preliminary data from the past two years. Water target and neutron flux results are in general agreement, and are consistent with the altitude-dependent scaling factors of Lal [Earth Planet. Sci. Lett. 104 (1991) 4241]. Significant differences between the sea level, latitude-dependent neutron flux data and Lal's predictions are possibly related to the response function of the detector.

  13. Cosmogenic radioberyllium and background radiation dose to the general public

    International Nuclear Information System (INIS)

    Poeschl, M.; Ohera, M.

    2008-01-01

    To discover the causes of the presence of abnormal Be concentrations (anthropogenic or natural or cosmogenic source) in the area of the Kralicky Sneznik mountain massive (in the northeast of the Czech Republic, altitude of about 800 m), concentrations of 7 Be and 10 Be were also assayed in selected environmental components in the years of 2005 - 2007. The 10 Be concentrations in soils (80.39x10 6 - 210.45x10 6 atom g -1 ) and activity concentrations of 7 Be in soils and wet deposition were very low (1.3 - 5.3 Bq kg -1 and 0.6 - 4.5 Bq l -1 , resp.). However, activities of 7 Be in birch leaves and grass (dry matter) reached relatively high values (up to 1000 Bq kg -1 ) and, in addition, showed out their significant seasonal growth. In the work the probable contribution of the cosmogenic 7 Be activities to background radiation dose to the general public is discussed. (authors)

  14. The solar forcing on the ground 7 Be concentration variability

    International Nuclear Information System (INIS)

    Talpos, S.; Borsan, D.H.

    2002-01-01

    7 Be, natural radionuclide, is produced by the interaction of cosmic radiation with oxygen and nitrogen molecules. 7 Be production in atmosphere depends on the intensity of cosmic radiation which is influenced by the Earth's magnetosphere. The magnetosphere shape depends on solar activity. This paper presents the influence of sunspots number (11 years period) on the ground 7 Be concentration variability. (authors)

  15. Superficial soil erosion assessment in agricultural land and bare land using 7Be fallout

    International Nuclear Information System (INIS)

    Marestoni, Luiz Diego

    2007-02-01

    Geologic and hydrologic phenomenon monitoring presents great environmental and financial interest and several radioisotopes, natural and artificial, have been used for this purpose. The more used are 137 Cs, 210 Pb not supported and 7 Be. In the present work, 7 Be was used to determine the soil erosion in three areas: one with soy ploughed at the direction of the slope, one with it perpendicular to the slope and one in an area with bare soil. 7 Be is a cosmogenic radionuclide, with half-life of 53.3 days, produced by spallation of oxygen and nitrogen by cosmic rays in the troposphere and stratosphere. 7 Be deposition occurs by dry and wet deposition, although wet deposition contributed by 95%. This can be verified through the measures of the 7 Be inventory correlated with the precipitation, which resulted in a good linear adjustment. The experimental set up consisted of two HPGe detectors: one with 66% of relative efficiency and one with 10% of relative efficiency, both detectors coupled to standard gamma ray spectrometry nuclear electronic chain. Soil samples were packed in 1 liter Marinelli beckers. Sampling was accomplished until the depth where 7 Be was present and it was possible to verify that its penetration in the soils could be very well adjusted by an exponential type function. The maximum beryllium-7 penetration in the bare soil without sign of soil erosion was 3 cm, that is, beryllium-7 is a useful tool as tracer for superficial soil erosion determination. The constant of mass relaxation h 0 was determined as 4.71 ± 0.36, result that is in agreement with other works in the international literature. It was verified that when the soy is ploughed perpendicular to the slope, the soil redistribution rate is smaller, resulting in economic advantage. The bare soil is very exposed to the erosion, because does not exist any barrier to contain the soil that flows at the direction of the slope, such fact was verified in this work, where it was determined that the

  16. Behaviour of 7Be air concentration observed during a period of 13 years and comparison with sun activity

    International Nuclear Information System (INIS)

    Cannizzaro, F.; Greco, G.; Raneli, M.; Spitale, M.C.; Tomarchio, E.

    1995-01-01

    The study reported in this work is addressed to review the time variations of the air-borne concentration of cosmogenic 7 Be obtained in the period January 1982-December 1994. Among other things, the observation of a long-term modulation present in the average monthly concentrations led us to perform a comparison with the behaviour in the same period of solar activity owing to its important influence on cosmic rays, from which the 7 Be production originates. (author)

  17. Cosmogenic activation of xenon and copper

    Energy Technology Data Exchange (ETDEWEB)

    Baudis, Laura; Kish, Alexander; Piastra, Francesco [University of Zuerich, Department of Physics, Zuerich (Switzerland); Schumann, Marc [University of Bern, Albert Einstein Center for Fundamental Physics, Bern (Switzerland)

    2015-10-15

    Rare event search experiments using liquid xenon as target and detection medium require ultra-low background levels to fully exploit their physics potential. Cosmic ray induced activation of the detector components and, even more importantly, of the xenon itself during production, transportation and storage at the Earth's surface, might result in the production of radioactive isotopes with long half-lives, with a possible impact on the expected background. We present the first dedicated study on the cosmogenic activation of xenon after 345 days of exposure to cosmic rays at the Jungfraujoch research station at 3470 m above sea level, complemented by a study of copper which has been activated simultaneously. We have directly observed the production of {sup 7}Be, {sup 101}Rh, {sup 125}Sb, {sup 126}I and {sup 127}Xe in xenon, out of which only {sup 125}Sb could potentially lead to background for a multi-ton scale dark matter search. The production rates for five out of eight studied radioactive isotopes in copper are in agreement with the only existing dedicated activation measurement, while we observe lower rates for the remaining ones. The specific saturation activities for both samples are also compared to predictions obtained with commonly used software packages, where we observe some underpredictions, especially for xenon activation. (orig.)

  18. Cosmogenic nuclide production within the atmosphere and long period comets

    Science.gov (United States)

    Overholt, Andrew C.

    The Earth is constantly bombarded by cosmic rays. These high energy particles collide with target nuclei, producing a shower of secondary particles. These secondaries contribute significantly to the radiation background at sea level and in the atmosphere, as well as producing rare cosmogenic nuclides. This contribution is variable over long time scales as astrophysical events change the cosmic ray flux incident on the Earth. Our work re-examines a previously proposed climate effect of increased cosmic ray flux due to galactic location. Although our work does not support this effect, cosmic ray secondaries remain a threat to terrestrial biota. We calculate the cosmogenic neutron flux within the atmosphere as a function of primary spectrum. This work is pivotal in determining the radiation dose due to any arbitrary astrophysical event where the primary spectrum is known. Additionally, this work can be used to determine the cosmogenic nuclide production from such an event. These neutrons are the fundamental source of cosmogenic nuclides within our atmosphere and extraterrestrial matter. We explore the idea that excursions in 14C and 10Be abundances in the atmosphere may arise from direct deposition by long-period comet impacts, and those in 26Al from any bolide. We find that the amount of nuclide mass on large long-period comets entering the Earth's atmosphere may be sufficient for creating anomalies in the records of 14C and 10Be from past impacts. In particular, the estimated mass of the proposed Younger Dryas comet is consistent with its having deposited sufficient isotopes to account for recorded nuclide increases at that time. The 26Al/10Be ratio is much larger in extraterrestrial objects than in the atmosphere, and so, we note that measuring this ratio in ice cores is a suitable further test for the Younger Dryas impact hypothesis. This portion of our work may be used to find possible impact events in the geologic record as well as determination of a large

  19. Implanted $^{7}$Be targets for the study of neutron interactions with $^{7}$Be

    CERN Multimedia

    The disagreement of the predicted abundance of primordial $^{7}$Li with the observed abundance is a longstanding problem in Big Bang Nucleosynthesis (BBN) theory (“Primordial $^{7}$Li problem”). While BBN theory correctly predicts the relative abundances of $^{2}$H/$^{1}$H, $^{3}$He/$^{1}$H and $^{4}$He/$^{1}$H (that vary over four orders of magnitudes), but it over-predicts the relative abundance of primordial $^{7}$Li/$^{1}$H by a factor of approximately 3-4 larger than observed (approximately 4-5$\\sigma$ discrepancy). Primordial $^{7}$Li is destroyed during the first 15 minutes primarily via the $^{7}$Li(p,$\\alpha$) reaction. Hence most of the primordial $^7$Li is predicted as the result of the (later when atoms are formed) electron capture $\\beta$-decay of the primordial $^{7}$Be that is produced primarily in the $^{3}$He($\\alpha$,$\\gamma$) )$^{7}$Be reaction. We propose to investigate the direct destruction of $^{7}$Be during (the first 15 minutes of) BBN via the $^{7}$Be(n,$\\alpha$) reaction to ch...

  20. Cosmogenic nuclides in recently fallen meteorites: Evidence for galactic cosmic ray variations during the period 1967--1978

    International Nuclear Information System (INIS)

    Evans, J.C.; Reeves, J.H.; Rancitelli, L.A.; Bogard, D.D.

    1982-01-01

    Cosmogenic radionuclides were measured on 48 fragments of 24 meteorites which fell between 1967 and 1978. Nondestructive gamma counting techniques were used to obtain data on 7 Be, 46 Sc, 48 V, 51 Cr, 54 Mn, 56 Co, 57 Co, 58 Co, and 60 Co on at least some of the samples. Sodium 22 and 26 Al measurements are reported on all 48 samples. In addition, new rare gas data and exposure ages are reported for the meteorites Guibga, Gorlovka, Dhajala, Louisville, Acapulco, Jilin, Kabo, Alta-Ameen, and Canon City. The cosmogenic radioisotope and rare gas data are interpreted in terms of a time dependent modulation of galactic cosmic rays spanning one full 11 year sun spot cycle. Special attention is given to the data on 22 Na, 46 Sc, 54 Mn, and 48 V with either 26 Al or 22 Ne/ 21 Ne used to provide a shielding correction. The shielding normalized data using the 26 Al method appear to correlate well with calculated production rates scaled against the Deep River neutron monitor. The data for the four isotopes are consistent with a production rate variation of a factor of 2.5--3 between solar maximum and solar minimum for sun spot cycle 20. These data demonstrate that the production rates of cosmic ray-produced nuclides in meteorites vary considerably according to modulation by the 11-year solar cycle and support the concept that variations of solar-modulated, cosmic ray flux of similar magnitude have occurred over much longer time periods

  1. New Hydrological Age-Dating Techniques Using Cosmogenic Radionuclides Beryllium-7 and Sodium-22

    Energy Technology Data Exchange (ETDEWEB)

    Frey, S.; Kuells, C. [Institute of Hydrology, Albert-Ludwigs-University of Freiburg (Germany); Schlosser, C. [Bundesamt fuer Strahlenschutz, Freiburg (Germany)

    2013-07-15

    Since atmospheric tritium levels have nearly reached the natural background, there is a need for further development of existing or additional methods for the age dating of young water. Non-gaseous age dating tracers are especially needed for hydrological applications in lakes, rivers and springs and for surface-groundwater interaction studies. Cosmogenically produced isotopes of sodium and beryllium ({sup 22}Na, {sup 7}Be, half-lives of 2.602 years and 53.29 days respectively) have been investigated as potential environmental tracers for residence time analysis of surface water. A simple chemical separation scheme for both radionuclides was established and {sup 7}Be was detected in both surface and groundwater samples. The ions were extracted from 500 L water using an ion exchange resin. The water samples were dated to ages of about 165 and 323 days for riverine samples and 475 days for a groundwater sample. Measurement was performed using a lead covered HPGe detector. These ages match ages previously reported using stable isotopes and tritium. (author)

  2. Ultrahigh energy cosmic ray fluxes and cosmogenic neutrinos

    Energy Technology Data Exchange (ETDEWEB)

    Stanev, Todor

    2013-04-15

    We discuss the possible origin of the two neutrino shower events reported by the IceCube Collaboration at the Neutrino 2012 conference in Kyoto, Japan. The suspicion early on was that these two events are due to cosmogenic neutrinos and possibly by electron antineutrinos generating the Glashow resonance. The difference of the energy of the W{sup −} in the resonance and the energy estimates of the detected cascade events makes this assumption unlikely. The conclusion then may be that these high energy neutrinos are produced at sources of high energy cosmic rays such as Active Galactic Nuclei.

  3. Muon and cosmogenic neutron detection in Borexino

    International Nuclear Information System (INIS)

    Bellini, G; Bonetti, S; Avanzini, M Buizza; Caccianiga, B; D'Angelo, D; Benziger, J; Bick, D; Cadonati, L; Calaprice, F; Chavarria, A; Galbiati, C; Carraro, C; Davini, S; Chepurnov, A; Derbin, A; Etenko, A; Feilitzsch, F von; Fomenko, K; Franco, D; Gazzana, S

    2011-01-01

    Borexino, a liquid scintillator detector at LNGS, is designed for the detection of neutrinos and antineutrinos from the Sun, supernovae, nuclear reactors, and the Earth. The feeble nature of these signals requires a strong suppression of backgrounds below a few MeV. Very low intrinsic radiogenic contamination of all detector components needs to be accompanied by the efficient identification of muons and of muon-induced backgrounds. Muons produce unstable nuclei by spallation processes along their trajectory through the detector whose decays can mimic the expected signals; for isotopes with half-lives longer than a few seconds, the dead time induced by a muon-related veto becomes unacceptably long, unless its application can be restricted to a sub-volume along the muon track. Consequently, not only the identification of muons with very high efficiency but also a precise reconstruction of their tracks is of primary importance for the physics program of the experiment. The Borexino inner detector is surrounded by an outer water-Cherenkov detector that plays a fundamental role in accomplishing this task. The detector design principles and their implementation are described. The strategies adopted to identify muons are reviewed and their efficiency is evaluated. The overall muon veto efficiency is found to be 99.992 % or better. Ad-hoc track reconstruction algorithms developed are presented. Their performance is tested against muon events of known direction such as those from the CNGS neutrino beam, test tracks available from a dedicated External Muon Tracker and cosmic muons whose angular distribution reflects the local overburden profile. The achieved angular resolution is ∼ 3 0 -5 0 and the lateral resolution is ∼ 35-50 cm, depending on the impact parameter of the crossing muon. The methods implemented to efficiently tag cosmogenic neutrons are also presented.

  4. Measurement of cosmogenic nuclides in extraterrestrial material

    International Nuclear Information System (INIS)

    Nishiizumi, K.; Arnold, J.R.

    1981-01-01

    Meteorites are rocks and pieces of iron-nickel alloy which fall to earth from time to time. They were formed about 4.6 billion years ago when our solar system was started. Thus it has been said that meteorites are the Rosetta stones of our solar system. We use the long-lived radioactive nuclides produced by cosmic ray bombardment, to study the history of the meteorites and also the history of the cosmic rays. When we have these historical facts in our hads, we hope we will be able to understand better how the solar system works, and how it got started. We can also learn more about the nature and origin of the cosmic rays. The accelerator mass spectrometry method helps not only reduce sample size, in most cases by two or three orders of magnitude, but opens another set of cosmogenic nuclides which have not been measured yet. Already 10 Be (t/sub 1/2 = 1.6 x 10 6 y), 36 Cl (3.0 x 10 5 y) and 129 I (1.6 x 10 7 y) in meteorites have been measured by accelerator mass spectrometry [3, 4, 7, 10]. Possible new candidates for measurement in extraterrestrial materials are 26 Al (7.2 x 10 5 y), 41 Ca (1.3 x 10 5 y), 60 Fe (approx. 10 5 y) and 59 Ni (7.6 x 10 4 y). We hope also to measure 146 Sm (1.0 x 10 8 y) and 92 Nb

  5. Transport of 7Be in a lithium loop

    International Nuclear Information System (INIS)

    Katsuta, H.; Anantatmula, R.P.; Bechtold, R.A.; Brehm, W.F.

    1982-07-01

    Beryllium-7 will be produced in the lithium target of the Fusion Materials Irradiation Test (FMIT) facility by the interaction of the deuteron beam with lithium by the two reactions 7 Li(d,2n) 7 Be and 6 Li(d,n) 7 Be. Recent estimates have shown that an equilibrium concentration of 45,000 curies of 7 Be will be present in FMIT lithium. Although this inventory of 7 Be corresponds to only 0.042 wt ppM in FMIT lithium, the radiation fields created can impose special design and maintenance requirements on the facility. A development program has been started at the Hanford Engineering Development Laboratory (HEDL) to investigate the transport of 7 Be in liquid lithium. Results obtained thus far indicated preferential deposition of 7 Be not only in the cold leg but also in the higher temperature region in a nonisothermal lithium system with a temperature gradient similar to that expected in FMIT. The results showed that 7 Be can diffuse into AISI 304 stainless steel (304) at FMIT operating temperatures; the diffusion coefficient of 7 Be in 304 was also calculated

  6. Cosmogenic Radionuclides in Bunburra Rockhole Achondrite Fall

    Czech Academy of Sciences Publication Activity Database

    Welten, K.C.; Nishiizumi, K.; Caffee, M. W.; Meier, M.M.M.; Bland, P.A.; Spurný, Pavel

    2009-01-01

    Roč. 44, Supplement (2009), A216-A216 ISSN 1086-9379. [Annual Meeting of the Meteoritical Society /72./. Nancy, 13.06.2009-18.06.2009] Institutional research plan: CEZ:AV0Z10030501 Keywords : Bunburra Rockhole * cosmogenic radionuclide concentrations Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 3.253, year: 2009

  7. Superficial soil erosion assessment in agricultural land and bare land using {sup 7}Be fallout; Estudo da redistribuicao de solo superficial em areas cultivadas e nao cultivadas utilizando o fallout do {sup 7}Be

    Energy Technology Data Exchange (ETDEWEB)

    Marestoni, Luiz Diego

    2007-02-15

    Geologic and hydrologic phenomenon monitoring presents great environmental and financial interest and several radioisotopes, natural and artificial, have been used for this purpose. The more used are {sup 137}Cs, {sup 210}Pb not supported and {sup 7}Be. In the present work, {sup 7}Be was used to determine the soil erosion in three areas: one with soy ploughed at the direction of the slope, one with it perpendicular to the slope and one in an area with bare soil. {sup 7}Be is a cosmogenic radionuclide, with half-life of 53.3 days, produced by spallation of oxygen and nitrogen by cosmic rays in the troposphere and stratosphere. {sup 7}Be deposition occurs by dry and wet deposition, although wet deposition contributed by 95%. This can be verified through the measures of the {sup 7}Be inventory correlated with the precipitation, which resulted in a good linear adjustment. The experimental set up consisted of two HPGe detectors: one with 66% of relative efficiency and one with 10% of relative efficiency, both detectors coupled to standard gamma ray spectrometry nuclear electronic chain. Soil samples were packed in 1 liter Marinelli beckers. Sampling was accomplished until the depth where {sup 7}Be was present and it was possible to verify that its penetration in the soils could be very well adjusted by an exponential type function. The maximum beryllium-7 penetration in the bare soil without sign of soil erosion was 3 cm, that is, beryllium-7 is a useful tool as tracer for superficial soil erosion determination. The constant of mass relaxation h{sub 0} was determined as 4.71 {+-} 0.36, result that is in agreement with other works in the international literature. It was verified that when the soy is ploughed perpendicular to the slope, the soil redistribution rate is smaller, resulting in economic advantage. The bare soil is very exposed to the erosion, because does not exist any barrier to contain the soil that flows at the direction of the slope, such fact was verified

  8. Cosmogenic radionuclides. Theory and applications in the terrestrial and space environments

    International Nuclear Information System (INIS)

    Beer, Juerg; Steiger, Rudolf von; McCracken, Ken

    2012-01-01

    Cosmogenic radionuclides are radioactive isotopes which are produced by natural processes and distributed within the Earth system. With a holistic view of the environment the authors show in this book how cosmogenic radionuclides can be used to trace and to reconstruct the history of a large variety of processes. They discuss the way in which cosmogenic radionuclides can assist in the quantification of complex processes in the present-day environment. The book aims to demonstrate to the reader the strength of analytic tools based on cosmogenic radionuclides, their contribution to almost any field of modern science, and how these tools may assist in the solution of many present and future problems that we face here on Earth. The book provides a comprehensive discussion of the basic principles behind the applications of cosmogenic (and other) radionuclides as environmental tracers and dating tools. The second section of the book discusses in some detail the production of radionuclides by cosmic radiation, their transport and distribution in the atmosphere and the hydrosphere, their storage in natural archives, and how they are measured. The third section of the book presents a number of examples selected to illustrate typical tracer and dating applications in a number of different spheres (atmosphere, hydrosphere, geosphere, biosphere, solar physics and astronomy). At the same time the authors have outlined the limitations of the use of cosmogenic radionuclides. Written on a level understandable by graduate students without specialist skills in physics or mathematics, the book addresses a wide audience, ranging from archaeology, biophysics, and geophysics, to atmospheric physics, hydrology, astrophysics and space science.

  9. Cosmogenic radionuclides. Theory and applications in the terrestrial and space environments

    Energy Technology Data Exchange (ETDEWEB)

    Beer, Juerg [Eidgenoessische Anstalt fuer Wasserversorgung, Abwasserreinigung und Gewaesserschutz, Duebendorf (Switzerland); Steiger, Rudolf von [International Space Science Insitute, Bern (Switzerland); McCracken, Ken [Maryland Univ., College Park (United States). IPST

    2012-07-01

    Cosmogenic radionuclides are radioactive isotopes which are produced by natural processes and distributed within the Earth system. With a holistic view of the environment the authors show in this book how cosmogenic radionuclides can be used to trace and to reconstruct the history of a large variety of processes. They discuss the way in which cosmogenic radionuclides can assist in the quantification of complex processes in the present-day environment. The book aims to demonstrate to the reader the strength of analytic tools based on cosmogenic radionuclides, their contribution to almost any field of modern science, and how these tools may assist in the solution of many present and future problems that we face here on Earth. The book provides a comprehensive discussion of the basic principles behind the applications of cosmogenic (and other) radionuclides as environmental tracers and dating tools. The second section of the book discusses in some detail the production of radionuclides by cosmic radiation, their transport and distribution in the atmosphere and the hydrosphere, their storage in natural archives, and how they are measured. The third section of the book presents a number of examples selected to illustrate typical tracer and dating applications in a number of different spheres (atmosphere, hydrosphere, geosphere, biosphere, solar physics and astronomy). At the same time the authors have outlined the limitations of the use of cosmogenic radionuclides. Written on a level understandable by graduate students without specialist skills in physics or mathematics, the book addresses a wide audience, ranging from archaeology, biophysics, and geophysics, to atmospheric physics, hydrology, astrophysics and space science.

  10. Isotope hydrology of catchment basins: lithogenic and cosmogenic isotopic systems

    Energy Technology Data Exchange (ETDEWEB)

    Nimz, G. J., LLNL

    1998-06-01

    A variety of physical processes affect solute concentrations within catchment waters. The isotopic compositions of the solutes can indicate which processes have determined the observed concentrations. These processes together constitute the physical history of the water. Many solutes in natural waters are derived from the interaction between the water and the rock and/or soil within the system - these are termed `lithogenic` solutes. The isotopic compositions of these solutes provide information regarding rock-water interactions. Many other solutes have their isotopic compositions determined both within and outside of the catchment - i.e., in addition to being derived from catchment rock and soil, they are solutes that are also transported into the catchment. Important members of this group include solutes that have isotopic compositions produced by atomic particle interactions with other nuclides. The source of the atomic particles can be cosmic radiation (producing `cosmogenic` nuclides in the atmosphere and land surface), anthropogenic nuclear reactions (producing `thermonuclear` nuclides), or radioactive and fission decay of naturally-occurring elements, principally {sup 238}U (producing `in-situ` lithogenic nuclides in the deep subsurface). Current language usage often combines all of the atomic particle-produced nuclides under the heading `cosmogenic nuclides`, and for simplicity we will often follow that usage here, although always indicating which variety is being discussed. This paper addresses the processes that affect the lithogenic and cosmogenic solute concentrations in catchment waters, and how the isotopic compositions of the solutes can be used in integrative ways to identify these processes, thereby revealing the physical history of the water within a catchment system. The concept of a `system` is important in catchment hydrology. A catchment is the smallest landscape unit that can both participate in all of the aspects of the hydrologic cycle and

  11. A new capability for ANTARES: {sup 7}Be by AMS for ice samples

    Energy Technology Data Exchange (ETDEWEB)

    Smith, A.M., E-mail: ams@ansto.gov.au [Australian Nuclear Science and Technology Organisation (ANSTO), Locked Bag 2001, Kirrawee, NSW 2232 (Australia); Mokhber-Shahin, L.; Simon, K.J. [Australian Nuclear Science and Technology Organisation (ANSTO), Locked Bag 2001, Kirrawee, NSW 2232 (Australia)

    2013-01-15

    ANSTO, in collaboration with Australian Antarctic Division (AAD) and the Antarctic Climate and Ecosystems Cooperative Research Centre (ACE CRC), has an on-going program of {sup 10}Be (t{sub Vulgar-Fraction-One-Half} = 1.39 Multiplication-Sign 10{sup 6} a) concentration measurement in firn and ice at Law Dome, Antarctica. In recent years snow pit samples have also been measured for {sup 7}Be (t{sub Vulgar-Fraction-One-Half} = 53.28 d) concentration as this isotope has the potential to give further insight into the transport and deposition of cosmogenic beryllium to Law Dome and so improve the use of {sup 10}Be as a proxy for solar activity. Early {sup 7}Be measurements were made by gamma-ray spectrometry (GRS) with typical counting times of 3 days. In 2010, we developed the capability for {sup 7}Be/{sup 9}Be measurement on the 10 MV ANTARES (Australian National Tandem Accelerator for Applied Research) accelerator using carbon foil post-stripping of {sup 7}Be{sup 3+} to {sup 7}Be{sup 4+} to eliminate the {sup 7}Li isobar. We describe the method and explain the advantages of using accelerator mass spectrometry (AMS) over GRS for {sup 7}Be analysis.

  12. Cosmogenic production of tritium in dark matter detectors

    Science.gov (United States)

    Amaré, J.; Castel, J.; Cebrián, S.; Coarasa, I.; Cuesta, C.; Dafni, T.; Galán, J.; García, E.; Garza, J. G.; Iguaz, F. J.; Irastorza, I. G.; Luzón, G.; Martínez, M.; Mirallas, H.; Oliván, M. A.; Ortigoza, Y.; Ortiz de Solórzano, A.; Puimedón, J.; Ruiz-Chóliz, E.; Sarsa, M. L.; Villar, J. A.; Villar, P.

    2018-01-01

    The direct detection of dark matter particles requires ultra-low background conditions at energies below a few tens of keV. Radioactive isotopes are produced via cosmogenic activation in detectors and other materials and those isotopes constitute a background source which has to be under control. In particular, tritium is specially relevant due to its decay properties (very low endpoint energy and long half-life) when induced in the detector medium, and because it can be generated in any material as a spallation product. Quantification of cosmogenic production of tritium is not straightforward, neither experimentally nor by calculations. In this work, a method for the calculation of production rates at sea level has been developed and applied to some of the materials typically used as targets in dark matter detectors (germanium, sodium iodide, argon and neon); it is based on a selected description of tritium production cross sections over the entire energy range of cosmic nucleons. Results have been compared to available data in the literature, either based on other calculations or from measurements. The obtained tritium production rates, ranging from a few tens to a few hundreds of nuclei per kg and per day at sea level, point to a significant contribution to the background in dark matter experiments, requiring the application of specific protocols for target material purification, material storing underground and limiting the time the detector is on surface during the building process in order to minimize the exposure to the most dangerous cosmic ray components.

  13. Precipitation scavenging of 7Be and 137Cs radionuclides in air

    International Nuclear Information System (INIS)

    Ioannidou, A.; Papastefanou, C.

    2006-01-01

    Atmospheric depositional fluxes of the naturally occurring 7 Be of cosmogenic origin and 137 Cs from fallout of the Chernobyl accident were measured over a 6-year period (January 1987-December 1992) at Thessaloniki, Greece (40 o 38'N, 22 o 58'E). Total precipitation accumulation during 1987-1992 varied between 33.7 cm and 65.2 cm, reflecting a relatively dry (precipitation-free) climate. The activity concentrations of 7 Be and 137 Cs in rainwater depended on the precipitation rate, being higher for low precipitation rates and lesser for high precipitation rates. 137 Cs was removed by rain and snow more efficiently than 7 Be. Snowfall was more efficient than rainfall in removing the radionuclides from the atmosphere. The annual bulk depositional fluxes of 7 Be varied between 477 and 1133 Bq m -2 y -1 and this variability was attributed to the amount of precipitation and the variations of the atmospheric concentrations of 7 Be. The annual bulk depositional fluxes of 137 Cs showed a significant decrease over time from 1987 to 1992, resulting in a removal half-life of 1.33 years. The presence of 137 Cs in air, and therefore in rainwater and snow, long after the Chernobyl accident (26 April 1986) was mainly due to the resuspension process. The normalized depositional fluxes of both radionuclides showed maximal values during the spring season where the maximum amount of precipitation occurred. The relatively high positive correlation between 7 Be and 137 Cs normalized depositional fluxes indicates that the scavenging process of local precipitation controlled the fluxes of both radionuclides. The dry depositional flux of 7 Be was less than 9.37% of total (wet and dry) depositional flux. The fraction of dry-to-total depositional flux of 137 Cs was much higher than that of 7 Be, due to the resuspended soil

  14. Experimental Determination of the Cosmogenic Ar Production Rate From Ca

    Science.gov (United States)

    Niedermann, S.; Schäfer, J. M.; Wieler, R.; Naumann, R.

    2005-12-01

    Cosmogenic 38Ar is produced in terrestrial surface rocks by spallation of target nuclides, in particular K and Ca. Though the presence of cosmogenic Ar in Ca-rich minerals has been demonstrated earlier [1], is has proven difficult to establish its production rate. To circumvent problems connected to 36Ar production by 35Cl neutron capture and different production rates from K and Ca, we have analyzed the noble gases in seven pyroxene separates (px) from the Antarctic Dry Valleys which are essentially free of Cl and K. The px were obtained from dolerite rocks, for which 3He and 21Ne exposure ages from 1.5 to 6.5 Ma have been reported [2]. The noble gases were extracted in two or three heating steps at GFZ Potsdam, yielding 38Ar/36Ar ratios up to 0.2283 ± 0.0008 (air: 0.1880). Ca (3.7-11.2 wt. %) is expected to be the only relevant target element for Ar production in the five pure px (ratio of 1.5 ± 0.2, we obtain cosmogenic 38Ar concentrations between 130 and 530x106 atoms/g. The 38Ar production rate was calculated based on 21Ne exposure ages [2], corrected for elevated nuclide production in Antarctica due to prevailing low air pressure and for the revised 21Ne production rate from Si. We obtain values between 188 ± 17 and 243 +110/-24 atoms (g Ca)-1 a-1 at sea level and high (northern) latitudes for four out of the five pure px, while one yields a very high value of 348 ± 70 atoms (g Ca)-1 a-1. Values above 250 atoms (g Ca)-1 a-1 are also obtained from two less pure px containing 0.3 and 0.9% K and from one feldspar/quartz accumulate, indicating that the production rate from K may be higher than that from Ca. The weighted mean (excluding the outlier) of ~200 atoms (g Ca)-1 a-1 is in excellent agreement with Lal's [3] theoretical estimate. [1] Renne et al., EPSL 188 (2001) 435. [2] Schäfer et al., EPSL 167 (1999) 215. [3] Lal, EPSL 104 (1991) 424.

  15. Cosmogenic nuclides principles, concepts and applications in the earth surface sciences

    CERN Document Server

    Dunai, Tibor J

    2010-01-01

    This is the first book to provide a comprehensive and state-of-the-art introduction to the novel and fast-evolving topic of in-situ produced cosmogenic nuclides. It presents an accessible introduction to the theoretical foundations, with explanations of relevant concepts starting at a basic level and building in sophistication. It incorporates, and draws on, methodological discussions and advances achieved within the international CRONUS (Cosmic-Ray Produced Nuclide Systematics) networks. Practical aspects such as sampling, analytical methods and data-interpretation are discussed in detail and an essential sampling checklist is provided. The full range of cosmogenic isotopes is covered and a wide spectrum of in-situ applications are described and illustrated with specific and generic examples of exposure dating, burial dating, erosion and uplift rates and process model verification. Graduate students and experienced practitioners will find this book a vital source of information on the background concepts and...

  16. Study of stratosphere-troposphere exchange via 10Be/7Be isotope ratios

    International Nuclear Information System (INIS)

    Priller, A.; Berger, M.; Golser, R.; Kutschera, W.; Steier, P.; Vockenhuber, C.; Wild, E.M.

    2001-01-01

    Full text: The present study is part of the European project STACCATO (influence of stratosphere-troposphere exchange in a changing climate on atmospheric transport and oxidation capacity). Stratosphere-troposphere exchange (STE) is one of the key factors controlling the budgets of ozone, water vapor and other substances in both the troposphere and the lower stratosphere. However, its contribution to their ozone budget relative to photo-chemical ozone formation from natural and anthropogenic precursor emissions is still uncertain. An international effort is made to estimate the strength of STE and its impact on tropospheric chemistry. The two cosmogenic radioisotopes of beryllium, 10 Be and 7 Be have very different half-lives of 1.51 Ma and 53.4 d, respectively. The combination of production rates, half-lives and different residence times in the stratosphere and troposphere, respectively, results in 10 Be/ 7 Be isotope ratios which can be used as fingerprints for STE. This ratio helps to give a much improved estimate of STE. However, only few 10 Be measurements exist, because its detection requires the rather elaborate method of accelerator mass spectrometry (AMS). At the AMS facility VERA we are now measuring the 10 Be content of air filters from the high-alpine stations 'Hoher Sonnblick', Austria, and 'Zugspitze', Germany. The TBe content is measured separately by decay counting. In this presentation, we want to describe the method of measuring 10 Be with AMS, and to discuss the results of first 10 Be/ 7 Be ratios. (author)

  17. Preparation and characterization of three 7Be targets for the measurement of the 7Be(n, p)7Li and 7Be(n, α)7Li reaction cross sections

    Science.gov (United States)

    Maugeri, E. A.; Heinitz, S.; Dressler, R.; Barbagallo, M.; Ulrich, J.; Schumann, D.; Colonna, N.; Köster, U.; Ayranov, M.; Vontobel, P.; Mastromarco, M.; Schell, J.; Correia, J. Martins; Stora, T.; n TOF Collaboration

    2018-05-01

    This manuscript describes the production of three targets obtained by implantation of different activities of 7Be into thin aluminium disks. Two of the produced targets were used to measure the 7Be(n, p)7Li cross section in the energy range of interest for the Big-Bang Nucleosynthesis. A third target was used to measure the cross sections of 7Be(n, p)7Li and 7Be(n, α)7Li nuclear reactions with cold and thermal neutrons, respectively. This paper describes also the characterization of the first two targets, performed after the neutron irradiation, in terms of implanted 7Be activities and spatial distributions.

  18. Atmospheric concentrations of 7Be, 10Be and 210Pb in northeast Asia

    International Nuclear Information System (INIS)

    Yamagata, T.; Tada, W.; T saito; Nagai, H.; Murayama, M.; Momoshima, N.; Matsuzaki, H.

    2005-01-01

    Cosmogenic nuclides 7 Be (T 1/2 = 53.3 d) and 10 Be (T 1/2 = 1.5 X 10 6 y) are very useful tracer for the aerosols originated in the upper atmosphere, In the case of 10 Be in surface air, however, two components from upper troposphere and from re-suspended dust from soil are mixed. We try to divide these sources, in order to know an interpretation of aerosol drives. To try to separate the two different source of 10 Be, we use 210 Pb (T 1/2 = 22.3y), progeny of 222 Rn, as continental component. In this study, the distribution of these nuclides in aerosols collected in the Northwest pacific and adjacent seas by employing the research Vessels as cut off the re-suspended dusts from soil are reported. Since research expeditions are mostly short term, continuous observation is very difficult. So we observed at Tokyo and Hachijo-Island, remote island located 300 km south from Tokyo, in 2002-2004. Seasonal variations for 7 Be, 10 Be and 210 Pb concentration were similar pattern at Tokyo and Hachijo-Island. The concentrations were high in April and October to November and low in July to August. Although 210 Pb concentration showed the seasonal variation similar to 7 Be concentration, the average 210 Pb concentration of Tokyo showed the value high about 35% as compared with Hachijo-Island, while the average 7 Be concentration having been mostly in agreement at both points. For the distribution of these nuclide, 7 Be and 10 Be concentrations in ocean air showed strong latitude dependence but 210 Pb concentration depend on distance from continent.

  19. Measurements of 14C in ancient ice from Taylor Glacier, Antarctica constrain in situ cosmogenic 14CH4 and 14CO production rates

    Science.gov (United States)

    Petrenko, Vasilii V.; Severinghaus, Jeffrey P.; Schaefer, Hinrich; Smith, Andrew M.; Kuhl, Tanner; Baggenstos, Daniel; Hua, Quan; Brook, Edward J.; Rose, Paul; Kulin, Robb; Bauska, Thomas; Harth, Christina; Buizert, Christo; Orsi, Anais; Emanuele, Guy; Lee, James E.; Brailsford, Gordon; Keeling, Ralph; Weiss, Ray F.

    2016-03-01

    Carbon-14 (14C) is incorporated into glacial ice by trapping of atmospheric gases as well as direct near-surface in situ cosmogenic production. 14C of trapped methane (14CH4) is a powerful tracer for past CH4 emissions from ;old; carbon sources such as permafrost and marine CH4 clathrates. 14C in trapped carbon dioxide (14CO2) can be used for absolute dating of ice cores. In situ produced cosmogenic 14C in carbon monoxide (14CO) can potentially be used to reconstruct the past cosmic ray flux and past solar activity. Unfortunately, the trapped atmospheric and in situ cosmogenic components of 14C in glacial ice are difficult to disentangle and a thorough understanding of the in situ cosmogenic component is needed in order to extract useful information from ice core 14C. We analyzed very large (≈1000 kg) ice samples in the 2.26-19.53 m depth range from the ablation zone of Taylor Glacier, Antarctica, to study in situ cosmogenic production of 14CH4 and 14CO. All sampled ice is >50 ka in age, allowing for the assumption that most of the measured 14C originates from recent in situ cosmogenic production as ancient ice is brought to the surface via ablation. Our results place the first constraints on cosmogenic 14CH4 production rates and improve on prior estimates of 14CO production rates in ice. We find a constant 14CH4/14CO production ratio (0.0076 ± 0.0003) for samples deeper than 3 m, which allows the use of 14CO for correcting the 14CH4 signals for the in situ cosmogenic component. Our results also provide the first unambiguous confirmation of 14C production by fast muons in a natural setting (ice or rock) and suggest that the 14C production rates in ice commonly used in the literature may be too high.

  20. A climatology of 7Be in surface air in European Union

    International Nuclear Information System (INIS)

    Hernández-Ceballos, M.A.; Cinelli, G.; Marín Ferrer, M.; Tollefsen, T.; De Felice, L.; Nweke, E.; Tognoli, P.V.; Vanzo, S.; De Cort, M.

    2015-01-01

    This study presents a European-wide analysis of the spatial and temporal distribution of the cosmogenic isotope 7 Be in surface air. This is the first time that a long term database of 34 sampling sites that regularly provide data to the Radioactivity Environmental Monitoring (REM) network, managed by the Joint Research Centre (JRC) in Ispra, is used. While temporal coverage varies between stations, some of them have delivered data more or less continuously from 1984 to 2011. The station locations were considerably heterogeneous, both in terms of latitude and altitude, a range which should ensure a high degree of representativeness of the results. The mean values of 7 Be activity concentration presented a spatial distribution value ranging from 2.0 to 5.4 mBq/m 3 over the European Union. The results of the ANOVA analysis of all 7 Be data available indicated that its temporal and spatial distributions were mainly explained by the location and characteristic of the sampling sites rather than its temporal distribution (yearly, seasonal and monthly). Higher 7 Be concentrations were registered at the middle, compared to high-latitude, regions. However, there was no correlation with altitude, since all stations are sited within the atmospheric boundary layer. In addition, the total and yearly analyses of the data indicated a dynamic range of 7 Be activity for each solar cycle and phase (maximum or minimum), different impact on stations having been observed according to their location. Finally, the results indicated a significant seasonal and monthly variation for 7 Be activity concentration across the European Union, with maximum concentrations occurring in the summer and minimum in the winter, although with differences in the values reached. The knowledge of the horizontal and vertical distribution of this natural radionuclide in the atmosphere is a key parameter for modelling studies of atmospheric processes, which are important phenomena to be taken into account in

  1. Using cosmogenic isotopes to measure basin-scale rates of erosion

    International Nuclear Information System (INIS)

    Bierman, P.R.; Steig, E.

    1992-01-01

    The authors present a new and different approach to interpreting the abundance of in situ-produced cosmogenic nuclides such as 36 Cl, 26 Al, and 10 Be. Unlike most existing models, which are appropriate for evaluating isotope concentrations on bedrock surfaces, this model can be used to interpret isotope concentration in fluvial sediment. Because sediment is a mixture of material derived from the entire drainage basin, measured isotope abundances can be used to estimate spatially-averaged rates of erosion and sediment transport. Their approach has the potential to provide geomorphologists with a relatively simple but powerful means by which to constrain rates of landscape evolution. The model considers the flux of cosmogenic isotopes into and out of various reservoirs. Implicit in model development are the assumptions that a geomorphic steady-state has been reached and that sampled sediment is spatially and temporally representative of all sediment leaving the basin. Each year, the impinging cosmic-ray flux produces a certain quantity of cosmogenic isotopes in the rock and soil of a drainage basin. For a basin in steady state, the outgoing isotope flux is also constant. They solve for the rate of mass loss as a function of isotope abundance in the sediment, the cosmic ray attenuation length, the isotope half life, and the effective isotope production rate. There are only a few published measurements of cosmogenic isotope abundance in sediment. They calculated model denudation rates for sediment samples from Zaire and central Texas. The denudation rates they calculated appear reasonable and are similar to those they have measured directly on granite landforms in Georgia and southeastern California and those calculated for the Appalachian Piedmont

  2. Cosmogenic nuclides in the Martian surface: constraints for sample recovery and transport

    International Nuclear Information System (INIS)

    Englert, P.A.J.

    1988-01-01

    Stable and radioactive cosmogenic nuclides and radiation damage effects such as cosmic ray tracks can provide information on the surface history of Mars. A recent overview on developments in cosmogenic nuclide research for historical studies of predominantly extraterrestrial materials was published previously. The information content of cosmogenic nuclides and radiation damage effects produced in the Martian surface is based on the different ways of interaction of the primary galactic and solar cosmic radiation (GCR, SCR) and the secondary particle cascade. Generally the kind and extent of interactions as seen in the products depend on the following factors: (1) composition, energy and intensity of the primary SCR and GCR; (2) composition, energy and intensity of the GCR-induced cascade of secondary particles; (3) the target geometry, i.e., the spatial parameters of Martian surface features with respect to the primary radiation source; (4) the target chemistry, i.e., the chemical composition of the Martian surface at the sampling location down to the minor element level or lower; and (5) duration of the exposure. These factors are not independent of each other and have a major influence on sample taking strategies and techniques

  3. 7Be fallout for superficial soil erosion assessment

    International Nuclear Information System (INIS)

    Marestoni, Luiz Diego; Martins, Eucarlos Lima; Appoloni, Carlos Roberto; Andrello, Avacir Casanova

    2009-01-01

    Geological and hydrological phenomenon monitoring presents great environmental and financial interest and several radioisotopes, natural and artificial, have been used for this purpose. In the present work, 7 Be was used to determine the soil erosion in three areas: one ploughed with soy at the direction of the slope, one with it perpendicular to the slope and an area with bare land. Beryllium-7 ( 7 Be) has half-life of 53.3 days and occurs in the upper troposphere and lower stratosphere and is produced naturally by spallation reaction of cosmic rays and solar energy particles with atoms of nitrogen, oxygen and carbon. The experiment was developed in tree areas located at Londrina city, north of State of Parana - Brazil, around of the coordinates 23deg20'34,0''S and 51deg12'34,0''W. The size of the areas was 15 m x 30 m, with a 10 % of sloping. The samples were analyzed by gamma ray spectrometry nuclear electronic chain. The calculated relaxation mass constant (h 0 ) was 4.71± 0.36, result that is in agreement with other works in the international literature. (author)

  4. In situ dating on Mars: A new approach to the K-Ar method utilizing cosmogenic argon

    Science.gov (United States)

    Cassata, William S.

    2014-01-01

    Cosmogenic argon isotopes are produced in feldspars via nuclear reactions between cosmic rays and Ca and K atoms within the lattice. These cosmogenic isotopes can be used as proxies for K and Ca, much like nuclear reactor-derived 39Ar and 37Ar are used as proxies for K and Ca, respectively, in 40Ar/39Ar geochronology. If Ca and K are uniformly distributed, then the ratio of radiogenic 40Ar (40Ar*) to cosmogenic 38Ar or 36Ar (38Arcos or 36Arcos) is proportional to the difference between the radioisotopic and exposure ages, as well as the K/Ca ratio of the degassing phase. Thus cosmogenic, radiogenic, and trapped Ar isotopes, all of which can be measured remotely and are stable over geologic time, are sufficient to generate an isochron-like diagram from which the isotopic composition of the trapped component may be inferred. Such data also provide a means to assess the extent to which the system has remained closed with respect to 40Ar*, thereby mitigating otherwise unquantifiable uncertainties that complicate the conventional K-Ar dating method.

  5. Enhanced cosmological GRB rates and implications for cosmogenic neutrinos

    International Nuclear Information System (INIS)

    Yueksel, Hasan; Kistler, Matthew D.

    2007-01-01

    Gamma-ray bursts, which are among the most violent events in the Universe, are one of the few viable candidates to produce ultra high-energy cosmic rays. Recently, observations have revealed that GRBs generally originate from metal-poor, low-luminosity galaxies and do not directly trace cosmic star formation, as might have been assumed from their association with core-collapse supernovae. Several implications follow from these findings. The redshift distribution of observed GRBs is expected to peak at higher redshift (compared to cosmic star formation), which is supported by the mean redshift of the Swift GRB sample, ∼3. If GRBs are, in fact, the source of the observed UHECR, then cosmic-ray production would evolve with redshift in a stronger fashion than has been previously suggested. This necessarily leads, through the GZK process, to an enhancement in the flux of cosmogenic neutrinos, providing a near-term approach for testing the gamma-ray burst-cosmic-ray connection with ongoing and proposed UHE neutrino experiments

  6. The 7Be profiles in the undisturbed soil used for reference site to estimate the soil erosion

    International Nuclear Information System (INIS)

    Raksawong, S; Bhongsuwan, T; Krmar, M

    2017-01-01

    The cosmogenic radionuclide 7 Be is increasingly used to obtain information on event-related soil erosion rates within agricultural landscapes. In this study, we select two undisturbed and flat areas to calculate the reference inventory and relaxation mass depth by using 7 Be technique to document short-term erosion. Our results showed that the depth distribution of 7 Be in undisturbed soil profiles was 1.0 cm in sites S02 and S03; the initial activities were 31.6 and 38.8 Bq.kg -1 , respectively. The relaxation mass depths were 5.4 and 7.2 kg.m -2 and the measured reference 7 Be inventories were 71 and 110 Bq.m -2 for sites S02 and S03, respectively. The difference values of the relaxation mass depth and the reference inventory of both sites implied that for determining a short term soil erosion using 7 Be, the reference site was suggested to be selected as close as possible to the study site. (paper)

  7. Reconstruction and measurement of cosmogenic signals in the neutrino experiment Borexino

    International Nuclear Information System (INIS)

    Meindl, Johannes Quirin

    2013-01-01

    Underground laboratories around the globe provide low-count rate experiments with the necessary shielding against the large flux of cosmic muons present at the Earth's surface. Depending on the depth of the underground site, the muon flux is reduced by up to eight orders of magnitude. Hower, the residual muons, and the neutrons and radioisotopes they produce in nuclear spallation processes, still pose a significant background for many of these experiments. This thesis focusses on cosmogenic background signals in the neutrino experiment Borexino, which is located at the Laboratori Nazionali del Gran Sasso underground site at a depth of 3800 meters of water equivalent. The work encompasses the identification, spatial reconstruction, and measurement of rates and production yields of these cosmogenic events. For the efficient tagging of long-lived cosmogenic radioisotopes of lifetimes in the order of seconds and longer, the spatial reconstruction of the parent muon is essential. Based on the characteristic light emission profile of muons crossing the inner detector of Borexino, a new muon track reconstruction algorithm was developed. Furthermore, to increase the performance of the existing muon track reconstruction of Borexino's outer detector, a routine was programmed to automatically calibrate the photomultiplier tubes in timing and charge response. Muons entering the experiment can cause fast secondary signals from decays and captures of stopped muons, and the captures of muon-induced neutrons. To identify these events in the high noise environment after the muon, dedicated search algorithms were developed. Based on the detected signals, these fast muon-correlated events are studied. The fraction and lifetime of stopped muons are found to be in agreement with expectations. The production yield of cosmogenic neutrons is measured to (3.10±0.07 stat ±0.08 syst ) . 10 -4 n/(μ . (g/cm 2 )). The corresponding capture time in the Borexino scintillator pseudocumene is

  8. Reconstruction and measurement of cosmogenic signals in the neutrino experiment Borexino

    Energy Technology Data Exchange (ETDEWEB)

    Meindl, Johannes Quirin

    2013-06-14

    Underground laboratories around the globe provide low-count rate experiments with the necessary shielding against the large flux of cosmic muons present at the Earth's surface. Depending on the depth of the underground site, the muon flux is reduced by up to eight orders of magnitude. Hower, the residual muons, and the neutrons and radioisotopes they produce in nuclear spallation processes, still pose a significant background for many of these experiments. This thesis focusses on cosmogenic background signals in the neutrino experiment Borexino, which is located at the Laboratori Nazionali del Gran Sasso underground site at a depth of 3800 meters of water equivalent. The work encompasses the identification, spatial reconstruction, and measurement of rates and production yields of these cosmogenic events. For the efficient tagging of long-lived cosmogenic radioisotopes of lifetimes in the order of seconds and longer, the spatial reconstruction of the parent muon is essential. Based on the characteristic light emission profile of muons crossing the inner detector of Borexino, a new muon track reconstruction algorithm was developed. Furthermore, to increase the performance of the existing muon track reconstruction of Borexino's outer detector, a routine was programmed to automatically calibrate the photomultiplier tubes in timing and charge response. Muons entering the experiment can cause fast secondary signals from decays and captures of stopped muons, and the captures of muon-induced neutrons. To identify these events in the high noise environment after the muon, dedicated search algorithms were developed. Based on the detected signals, these fast muon-correlated events are studied. The fraction and lifetime of stopped muons are found to be in agreement with expectations. The production yield of cosmogenic neutrons is measured to (3.10{+-}0.07{sub stat}{+-}0.08{sub syst}) . 10{sup -4} n/({mu} . (g/cm{sup 2})). The corresponding capture time in the

  9. Search for a resonant enhancement of the 7Be + d reaction and primordial 7Li abundances

    International Nuclear Information System (INIS)

    O'Malley, Patrick; Adekola, A.S.; Cizewski, J.A.; Howard, M.E.; Strauss, S.; Bardayan, Daniel W.; Chae, Kyung Yuk; Nesaraja, Caroline D.; Pain, Steven D.; Smith, Michael Scott; Ahn, S.H.; Jones, K.L.; Pittman, S.T.; Schmitt, Kyle; Graves, S.; Kozub, R.L.; Shriner, J.F. Jr.; Wheeler, J.L.; Linhardt, Laura; Matos, M.; Moazen, B.M.; Peters, W.A.; Spassova, I.

    2011-01-01

    Big Bang nucleosynthesis calculations, constrained by the Wilkinson Microwave Anisotropy Probe results, produce 7 Li abundances almost a factor of four larger than those extrapolated from observations. Since primordial 7 Li is believed to be mostly produced by the beta decay of 7 Be, one proposed solution to this discrepancy is a resonant enhancement of the 7 Be(d,p)2α reaction rate through the 5/2 + 16.7-MeV state in 9 B. The 2 H( 7 Be,d) 7 Be reaction was used to search for such a resonance; none was observed. An upper limit on the width of the proposed resonance was deduced.

  10. Seasonal variability in 7Be depositional fluxes at Granada, Spain

    International Nuclear Information System (INIS)

    Gonzalez-Gomez, C.; Azahra, M.; Lopez-Penalver, J.J.; Camacho-Garcia, A.; Bardouni, T.El.; Boukhal, H.

    2006-01-01

    Measurement of 7 Be depositional fluxes at Granada, Spain (37 o 10'50''N-3 o 35'44''W, altitude 670 m) in the period 1995 through 1998 indicates substantial variations between the four seasons and also between corresponding seasons in different years, ranging from 23.6 to 242 Bq m -2 per season. A strongly positive correlation with precipitation is shown, which explains about 70% of the variations in the 7 Be depositional fluxes over the 16 seasons studied. The depositional 7 Be flux is on the average highest in the fall and lowest in the summer. The study shows that precipitation primarily controls the 7 Be depositional flux and plays a dominant role in the removal of 7 Be from the troposphere. The average annual 7 Be depositional flux at Granada amounts to 469+145 Bq m -2

  11. Cosmogenic radionuclide carriers in the atmosphere

    International Nuclear Information System (INIS)

    Lujaniene, G.; Lujanas, V.

    1998-01-01

    The investigation of radionuclides ( 7 Be 32,33 P and 35 S) and stable sulfur and phosphorus forms was based on the Tessier sequential extraction method. The properties of radionuclide carriers can be transformed in the atmosphere in a very short time (days, hours), in contrast to soil and the hydrosphere. Oxidation processes proceeding in the atmosphere induce changes in the aerosol carrier properties. The aerosol can be characterized by low pH and high Eh values corresponding to high 7Be solubility. The unexpectedly high negative Eh values obtained in dry summer period indicate that the 7 Be 32,33 P aerosol is bound to insoluble carriers. 137 Cs solubility does not depend on changes in pH. This can be explained by the fact that in contrast to 7 Be, 137 Cs is associated with the exchangeable fraction. Cs ions can be replaced not only by H + but also by NH 4 + and other ions. 7 Be aerosols collected at the seaside of the Baltic sea (Preila) were found to be more soluble than those in Vilnius, their solubility was up to 50-90 % and clear dependence between 7 Be solubility, pH and Eh was not observed. It can be attributed to differences in the atmospheric aerosol composition (e.g. soluble chlorides) in Vilnius and Preila. A great variety of 7 Be carriers properties as well as their dependence on the season and the existence of admixtures in the atmosphere require great caution in applying this isotope in tracer investigations. Soluble carriers are removed faster from the atmosphere by precipitation. The significance of this fact is confirmed by the ratio of 7 Be/ 32 P in the air and precipitation. Both soluble and insoluble aerosols can be formed depending on the environmental conditions

  12. Concentration of 7Be in surface air at Suva, Fiji

    International Nuclear Information System (INIS)

    Garimella, S.; Koshy, K.

    1998-01-01

    A high-volume air sampler and a high-resolution gamma-ray spectrometer have been in use since August 1997 at the University of the South Pacific to measure the activity of 7 Be in surface air at Suva, the capital city of Fiji. Preliminary measurements during August - November 1997 indicate that the average concentration of 7 Be in surface air is approximately 4.0 mBq m -3 . Further measurements are in progress

  13. Present status and prospects of ultralow level radioactivity measurements (5). Measurement of time variations of cosmic rays in the past by the detection of ultralow level 14C and 7Be radioactivity

    International Nuclear Information System (INIS)

    Sakurai, Hirohisa

    2006-01-01

    The change of the concentration of 7 Be in air and 14 C in the tree ring, cosmogenic nuclide, was measured by the ultralow level radioactivity measurement method. The concentration of 14 C in the tree ring was changed by the intensity of cosmic ray in the past. Cosmic ray and cosmogenic nuclide, solar activity and change of cosmic ray intensity, the continuous measurement of 7 Be concentration in atmosphere, and measurement of 14 C concentration in the old tree ring are reported. 14 C concentration in tree ring is measured by the ultralow level liquid scintillation measuring system (Quantulus) and 14 C concentration in the tree ring of Japanese cedar at Akita and Murou was changed by nuclear tests in air. 14 C concentration of Chokaijindaisugi, cryptomeria, about 2500 years old, is changed periodically about 10.1 years as almost same as the sunspot activity cycle. (S.Y.)

  14. PRODUCTION AND RECOIL LOSS OF COSMOGENIC NUCLIDES IN PRESOLAR GRAINS

    International Nuclear Information System (INIS)

    Trappitsch, Reto; Leya, Ingo

    2016-01-01

    Presolar grains are small particles that condensed in the vicinity of dying stars. Some of these grains survived the voyage through the interstellar medium (ISM) and were incorporated into meteorite parent bodies at the formation of the Solar System. An important question is when these stellar processes happened, i.e., how long presolar grains were drifting through the ISM. While conventional radiometric dating of such small grains is very difficult, presolar grains are irradiated with galactic cosmic rays (GCRs) in the ISM, which induce the production of cosmogenic nuclides. This opens the possibility to determine cosmic-ray exposure (CRE) ages, i.e., how long presolar grains were irradiated in the ISM. Here, we present a new model for the production and loss of cosmogenic 3 He, 6,7 Li, and 21,22 Ne in presolar SiC grains. The cosmogenic production rates are calculated using a state-of-the-art nuclear cross-section database and a GCR spectrum in the ISM consistent with recent Voyager data. Our findings are that previously measured 3 He and 21 Ne CRE ages agree within the (sometimes large) 2 σ uncertainties and that the CRE ages for most presolar grains are smaller than the predicted survival times. The obtained results are relatively robust since interferences from implanted low-energy GCRs into the presolar SiC grains and/or from cosmogenic production within the meteoroid can be neglected.

  15. Off-line production of a sup 7 Be radioactive ion beam

    CERN Document Server

    Gialanella, L; De Cesare, N; D'Onofrio, A; Romano, M; Campajola, L; Formicola, A; Fülöp, Z; Gyürky, G; Imbriani, G; Lubritto, C; Ordine, A; Roca, V; Rogalla, D; Rolfs, C; Russo, M; Sabbarese, C; Somorjai, E; Strieder, F; Terrasi, F; Trautvetter, H P

    2002-01-01

    A sup 7 Be ion beam of several particle pA at 8 MeV has been produced at the TTT3 tandem of the University 'Federico II' in Naples. The sup 7 Be nuclides were formed via the sup 7 Li(p,n) sup 7 Be reaction using a metallic Li target and an 11.4 MeV proton beam of 20 mu A intensity, delivered by the cyclotron in Debrecen. Methods of hot chemistry were used to extract the sup 7 Be nuclides from the Li matrix and to prepare the sup 7 Be cathodes for the ion sputter source of the tandem. Examples of sup 7 Be beam applications are given.

  16. Estimation of groundwater residence time and evaluation of geomorphological processes using cosmogenic and terrigenic radionuclides and isotopes of noble gases

    International Nuclear Information System (INIS)

    Mahara, Yasunori; Ohta, Tomoko; Igarashi, Toshifumi

    2013-01-01

    In this paper, the estimation of groundwater residence time and geomorphological changing processes are discussed by focusing on isotopes of noble gases and radionuclides with a long half-life as an environmental tracer. Noble gases and radionuclides are produced in the atmospheric air and terrestrial rocks by spallation and various muon reactions during cosmic rays irradiation. Groundwater dating and geomorphological changing are estimated from changes in the number of atoms of cosmogenic and terrigenic nuclides in groundwater and terrestrial rock. The main tools of groundwater dating are combination of the dissolved helium and tritium (half-life T 1/2 =12.3 y) for younger groundwater less than 60 years of residence time, and of the dissolved helium and 36 Cl (T 1/2 =3.01 x 10 5 y) for older groundwater over million years. On the other hand, the main tools on the geomorphological changes are the estimation of exposure time using cosmogenic radionuclides ( 10 Be(half-life T 1/2 =1.6 x 10 6 y), 14 C (T 1/2 =5730 y), 26 Al (T 1/2 =7.16 x 10 5 y) and 36 Cl) and cosmogenic stable noble gases ( 3 He and 21 Ne) produced in rock. (author)

  17. 7Be solar neutrino measurement with KamLAND

    Science.gov (United States)

    Gando, A.; Gando, Y.; Hanakago, H.; Ikeda, H.; Inoue, K.; Ishidoshiro, K.; Ishikawa, H.; Kishimoto, Y.; Koga, M.; Matsuda, R.; Matsuda, S.; Mitsui, T.; Motoki, D.; Nakajima, K.; Nakamura, K.; Obata, A.; Oki, A.; Oki, Y.; Otani, M.; Shimizu, I.; Shirai, J.; Suzuki, A.; Tamae, K.; Ueshima, K.; Watanabe, H.; Xu, B. D.; Yamada, S.; Yamauchi, Y.; Yoshida, H.; Kozlov, A.; Takemoto, Y.; Yoshida, S.; Grant, C.; Keefer, G.; McKee, D. W.; Piepke, A.; Banks, T. I.; Bloxham, T.; Freedman, S. J.; Fujikawa, B. K.; Han, K.; Hsu, L.; Ichimura, K.; Murayama, H.; O'Donnell, T.; Steiner, H. M.; Winslow, L. A.; Dwyer, D.; Mauger, C.; McKeown, R. D.; Zhang, C.; Berger, B. E.; Lane, C. E.; Maricic, J.; Miletic, T.; Learned, J. G.; Sakai, M.; Horton-Smith, G. A.; Tang, A.; Downum, K. E.; Tolich, K.; Efremenko, Y.; Kamyshkov, Y.; Perevozchikov, O.; Karwowski, H. J.; Markoff, D. M.; Tornow, W.; Detwiler, J. A.; Enomoto, S.; Heeger, K.; Decowski, M. P.; KamLAND Collaboration

    2015-11-01

    We report a measurement of the neutrino-electron elastic scattering rate of 862 keV 7Be solar neutrinos based on a 165.4 kt d exposure of KamLAND. The observed rate is 582 ±94 (kt d)-1, which corresponds to an 862-keV 7Be solar neutrino flux of (3.26 ±0.52 ) ×109cm-2s-1 , assuming a pure electron-flavor flux. Comparing this flux with the standard solar model prediction and further assuming three-flavor mixing, a νe survival probability of 0.66 ±0.15 is determined from the KamLAND data. Utilizing a global three-flavor oscillation analysis, we obtain a total 7Be solar neutrino flux of (5.82 ±1.02 ) ×109cm-2s-1 , which is consistent with the standard solar model predictions.

  18. Concentration of 7Be in surface air at Suva, Fiji

    International Nuclear Information System (INIS)

    Garimella, S.; Koshy, K.

    1998-01-01

    A high-volume air sampler and a high-resolution gamma-ray spectrometer have been in use since August 1997 at the University of the South Pacific to measure the activity of 7 Be in surface air at Suva, the capital city of Fiji. Preliminary measurements during August-November 1997 indicate that the average concentration of 7 Be in surface air is approximately 4.0 mBq m -3 . Further measurements are in progress. (author). 4 refs., 1 fig

  19. 600 MeV Simulation of the Production of Cosmogenic Nuclides in Meteorites by Galactic Protons

    CERN Multimedia

    2002-01-01

    A large variety of stable and radioactive nuclides is produced by the interaction of solar and galactic cosmic rays with extraterrestrial matter. Measurements of such cosmogenic nuclides provide information about the constancy of cosmic ray fluxes in space and time and about the irradiation history of individual extraterrestrial objects provided that there exist reliable models describing the production process. For the calculation of the depth dependent production of cosmogenic nuclides in meteorites no satisfactory Therefore, the irradiation of small stony meteorites (radii~$<$~40~cm) by galactic protons is simulated in a series of thick target irradiation experiments at the 600~MeV proton beam of the SC. \\\\ \\\\ The thick targets are spheres (R = 5, 15, 25 cm) and are made out of diorite because of its low water content, its high density (3.0~g/cm|3) and because it provides a good approximation of the chemical composition of some common meteorite clas These spheres will also contain a wide variety of pure...

  20. Precision measurement of the $^{7}$Be(p, $\\gamma$)$\\,^{8}$B cross section with an implanted $^{7}$Be target

    CERN Document Server

    Baby, L.T.; Goldring, G.; Hass, M.; Weissman, L.; Fedoseyev, V.N.; Koester, U.; Nir-El, Y.; Haquin, G.; Gaggeler, H.W.; Weinreich, R.

    2003-01-01

    The $^{7}$Be(p, $\\gamma$) $\\,^{8}$B reaction plays a central role in the evaluation of solar neutrino fluxes. We report on a new precision measurement of the cross section of this reaction, following our previous experiment with an implanted $^{7}$Be target, a raster- scanned beam, and the elimination of the backscattering loss. The new measurement incorporates a more abundant $^{7}$Be target and a number of improvements in design and procedure. The point at E$_{lab}$ = 991 keV was measured several times under varying experimental conditions, yielding a value of S$_{17}$(E$_{c.m.}$ = 850 keV) = 24.0 $\\pm$ 0.5 eV b. Measurements were carried out at lower energies as well. Because of the precise knowledge of the implanted $^{7}$Be density profile, it was possible to reconstitute both the off- and on-resonance parts of the cross section and to obtain from the entire set of measurements an extrapolated value of S$_{17}$(0)=21.2 $\\pm$ 0.7 eV b.

  1. Continuous wet-only and dry-only deposition measurements of 137Cs and 7Be: an indicator of their origin

    International Nuclear Information System (INIS)

    Rosner, G.; Hoetzl, H.; Winkler, R.

    1996-01-01

    Series of monthly values of 137 Cs and 7 Be wet and dry deposition were measured with a wet-only and a dry-only collector each having an area of 2.25 m 2 . The results are presented for the period from November 1991 to May 1995. The behaviour of resuspended, Chernobyl-derived radiocesium is shown to be significantly different from that of cosmogenic 7 Be and from that of global fallout 137 Cs from nuclear weapons testing. The dry-to-total ratio of 0.65, the dry deposition velocity of 1.5 cm s -1 , the close correlation to the total amount of solids collected and the absence of a correlation between activity deposition and amount of rainfall point to a strong similarity in the deposition behaviour of present radiocesium and that of stable elements of terrestrial origin. (author)

  2. Continuous wet-only and dry-only deposition measurements of {sup 137}Cs and {sup 7}Be: an indicator of their origin

    Energy Technology Data Exchange (ETDEWEB)

    Rosner, G.; Hoetzl, H.; Winkler, R. [GSF - Forschungszentrum fuer Umwelt und Gesundheit Neuherberg GmbH, Oberschleissheim (Germany). Inst. fuer Strahlenschutz

    1996-09-01

    Series of monthly values of {sup 137}Cs and {sup 7}Be wet and dry deposition were measured with a wet-only and a dry-only collector each having an area of 2.25 m{sup 2}. The results are presented for the period from November 1991 to May 1995. The behaviour of resuspended, Chernobyl-derived radiocesium is shown to be significantly different from that of cosmogenic {sup 7}Be and from that of global fallout {sup 137}Cs from nuclear weapons testing. The dry-to-total ratio of 0.65, the dry deposition velocity of 1.5 cm s{sup -1}, the close correlation to the total amount of solids collected and the absence of a correlation between activity deposition and amount of rainfall point to a strong similarity in the deposition behaviour of present radiocesium and that of stable elements of terrestrial origin. (author).

  3. Constraining local subglacial bedrock erosion rates with cosmogenic nuclides

    Science.gov (United States)

    Wirsig, Christian; Ivy-Ochs, Susan; Christl, Marcus; Reitner, Jürgen; Reindl, Martin; Bichler, Mathias; Vockenhuber, Christof; Akcar, Naki; Schlüchter, Christian

    2014-05-01

    The constant buildup of cosmogenic nuclides, most prominently 10Be, in exposed rock surfaces is routinely employed for dating various landforms such as landslides or glacial moraines. One fundamental assumption is that no cosmogenic nuclides were initially present in the rock, before the event to be dated. In the context of glacially formed landscapes it is commonly assumed that subglacial erosion of at least a few meters of bedrock during the period of ice coverage is sufficient to remove any previously accumulated nuclides, since the production of 10Be ceases at a depth of 2-3 m. Insufficient subglacial erosion leads to overestimation of surface exposure ages. If the time since the retreat of the glacier is known, however, a discordant concentration of cosmogenic nuclides delivers information about the depth of subglacial erosion. Here we present data from proglacial bedrock at two sites in the Alps. Goldbergkees in the Hohe Tauern National Park in Austria and Gruebengletscher in the Grimsel Pass area in Switzerland. Samples were taken inside as well as outside of the glaciers' Little Ice Age extent. Measured nuclide concentrations are analyzed with the help of a MATLAB model simulating periods of exposure or glacial cover of user-definable length and erosion rates.

  4. The production rate of cosmogenic deuterium at the Moon's surface

    Science.gov (United States)

    Füri, Evelyn; Deloule, Etienne; Trappitsch, Reto

    2017-09-01

    The hydrogen (D/H) isotope ratio is a key tracer for the source of planetary water. However, secondary processes such as solar wind implantation and cosmic ray induced spallation reactions have modified the primordial D/H signature of 'water' in all rocks and soils recovered on the Moon. Here, we re-evaluate the production rate of cosmogenic deuterium (D) at the Moon's surface through ion microprobe analyses of hydrogen isotopes in olivines from eight Apollo 12 and 15 mare basalts. These in situ measurements are complemented by CO2 laser extraction-static mass spectrometry analyses of cosmogenic noble gas nuclides (3He, 21Ne, 38Ar). Cosmic ray exposure (CRE) ages of the mare basalts, derived from their cosmogenic 21Ne content, range from 60 to 422 Ma. These CRE ages are 35% higher, on average, than the published values for the same samples. The amount of D detected in the olivines increases linearly with increasing CRE ages, consistent with a production rate of (2.17 ± 0.11) ×10-12 mol(g rock)-1 Ma-1. This value is more than twice as high as previous estimates for the production of D by galactic cosmic rays, indicating that for water-poor lunar samples, i.e., samples with water concentrations ≤50 ppm, corrected D/H ratios have been severely overestimated.

  5. Atmospheric deposition of 7Be by rain events, incentral Argentina

    Science.gov (United States)

    Ayub, J. Juri; Di Gregorio, D. E.; Huck, H.; Velasco, H.; Rizzotto, M.

    2008-08-01

    Beryllium-7 is a natural radionuclide that enters into the ecosystems through wet and dry depositions and has numerous environmental applications in terrestrial and aquatic ecosystems. Atmospheric wet deposition of 7Be was measured in central Argentina. Rain traps were installed (1 m above ground) and individual rain events have been collected. Rain samples were filtered and analyzed by gamma spectrometry. The gamma counting was undertaken using a 40%-efficient p-type coaxial intrinsic high-purity natural germanium crystal built by Princeton Gamma-Tech. The cryostat was made from electroformed high-purity copper using ultralow-background technology. The detector was surrounded by 50 cm of lead bricks to provide shielding against radioactive background. The detector gamma efficiency was determined using a water solution with known amounts of chemical compounds containing long-lived naturally occurring radioisotopes, 176Lu, 138La and 40K. Due to the geometry of the sample and its position close to the detector, the efficiency points from the 176Lu decay, had to be corrected for summing effects. The measured samples were 400 ml in size and were counted curing one day. The 7Be detection limit for the present measurements was as low as 0.2 Bq l-1. Thirty two rain events were sampled and analyzed (November 2006-May 2007). The measured values show that the events corresponding to low rainfall (<20 mm) are characterized by significantly higher activity concentrations (Bq l-1). The activity concentration of each individual event varied from 0.8 to 3.5 Bq l-1, while precipitations varied between 4 and 70 mm. The integrated activity by event of 7Be was fitted with a model that takes into account the precipitation amount and the elapsed time between two rain events. The integrated activities calculated with this model show a good agreement with experimental values.

  6. Analysis of the atmospheric 7Be radioactivity by neural network

    International Nuclear Information System (INIS)

    Moroz, Z.; Myslek-Laurikainen, B.; Matul, M.; Mikolajewski, S.; Preibisz, Z.; Trzaskowaka, H.; Kownacki, C.

    2002-01-01

    Computational methods of artificial intelligence (neural networks) and modern signal processing (wavelet decomposition were applied for the analysis of atmospheric 7 Be radioactivity data. Measurements were performed each week during 1994-2001 in the sampling station placed at Swider Geophysical Observatory. Raw data as well as those averaged over 4 and 10 weeks were used. Ability of the neural networks for the purpose of representation, interpolation and prediction was tested. The corresponding relative errors are calculated. Next, the time sequences were decomposed using the wavelet method and eight components of different time scales were obtained. Neural networks were applied separately to each of those components. Application of such analysis and their possible extensions useful for the construction of phenomeno-logical models of atmospheric radioactivity are discussed. (author)

  7. Aerosol deposition velocities on the Pacific and Atlantic oceans calculated from 7Be measurements

    International Nuclear Information System (INIS)

    Young, J.A.; Silker, W.B.

    1980-01-01

    The concentrations of 7 Be have been measured in Pacific and Atlantic ocean water for the past several years to determine the deposition velocity of aerosol particles on the ocean surface. 7 Be is produced at a relatively constant rate in the atmosphere by spallation reactions of cosmic rays with atmospheric nitrogen and oxygen. Immediately after its formation 7 Be becomes attached to aerosol particles, and therefore can serve as tracers of the subsequent behavior of these particles. Isopleths of 7 Be surface water concentrations, 7 Be inventory in the ocean, and deposition velocity have been prepared for the Pacific Ocean from 30 0 S to 60 0 N and for the Atlantic Ocean from 10 0 N to 55 0 N. The concentrations, inventories and deposition velocities tended to be higher in regions where precipitation was high, and generally increased with latitude. The average flux of 7 Be across the ocean surface was calculated to be 0.027 atoms cm -2 s -1 which is probably not significantly greater than the worldwide average 7 Be flux across land and ocean surfaces of 0.022 atoms cm -2 s -1 calculated by Lal and Peters. The average deposition velocity was calculated to be 0.80 cm s -1 . This value may be 10-50% too low, since it was calculated using atmospheric 7 Be concentrations which were measured at continental stations. Measurements of atmospheric 7 Be concentrations at ocean stations suggest that the concentrations at the continental stations averaged 10-50% higher than the concentrations over the ocean. (orig.)

  8. Cosmogenic Secondary Radiation from a Nearby Supernova

    Science.gov (United States)

    Overholt, Andrew

    2017-01-01

    Increasing evidence has been found for multiple supernovae within 100 pc of the solar system. Supernovae produce large amounts of cosmic rays which upon striking Earth's atmosphere, produce a cascade of secondary particles. Among these cosmic ray secondaries are neutrons and muons, which penetrate far within the atmosphere to sea level and even below sea level. Muons and neutrons are both forms of ionizing radiation which have been linked to increases in cancer, congenital malformations, and other maladies. This work focuses on the impact of muons, as they penetrate into ocean water to impact the lowest levels of the aquatic food chain. We have used monte carlo simulations (CORSIKA, MCNPx, and FLUKA) to determine the ionizing radiation dose due to cosmic ray secondaries. This information shows that although most astrophysical events do not supply the necessary radiation flux to prove dangerous; there may be other impacts such as an increase to mutation rate.

  9. Aerosol deposition velocities on the Pacific and Atlantic oceans calculated from 7Be measurements

    International Nuclear Information System (INIS)

    Young, J.A.; Silker, W.B.

    1979-01-01

    The concentrations of 7 Be were measured in Pacific and Atlantic ocean water for past several years to determine the deposition velocity of aerosol particles on the ocean surface. Beryllium-7 is produced at a relatively constant rate in the atmosphere by spallation reactions of cosmic rays with atmospheric nitrogen and oxygen. Immediately after its formation 7 Be becomes attached to aerosol particles, and therefore can serve as tracers of the subsequent behavior of these particles. Isopleths of 7 Be surface water concentration, 7 Be inventory in the ocean, and deposition velocity have been prepared for the Pacific Ocean from 30 0 S to 60 0 N and for the Atlantic Ocean from 10 0 N to 55 0 N. The concentrations, inventories and deposition velocities tended to be higher in regions where precipitation was high, and generally increased with latitude. The average flux of 7 Be across the ocean surface was calculated to be 0.027 atoms cm -2 sec -1 which is probably not significantly greater than the worldwide average 7 Be flux across land and ocean surfaces of 0.022 atoms cm -2 sec -1 calculated by Lal and Peters. The average deposition velocity was calculated to be 0.80 cm sec -1 . This value may be 10 to 30% too low, since it was calculated using atmospheric 7 Be concentrations which were measured at continental stations. Measurements of atmospheric 7 Be concentrations at ocean stations suggest that the concentrations at the continental stations averaged 10 to 30% higher than the concentrations over the ocean

  10. What we know about Oslo meteorite from cosmogenic isotope analysis

    Science.gov (United States)

    Tymiński, Z.; Stolarz, M.; Kubalczak, T.; Zaręba, P.; Burski, M.; Bilet, M.; Miśta, E.; Tymińska, K.; Kołakowska, E.; Burakowska, A.; Żołądek, P.; Olech, A.; Wiśniewski, M.; Listkowska, A.; Saganowski, P.

    2015-10-01

    The fragments of an asteroid that had crashed over Norway were found in a few locations in Oslo at the beginning of March 2012. Later on some pieces of meteorite from the most South area were collected by the Meteoritical Section members of Comet and Meteor Workshop (PKiM) with the help of local meteoritical authorities. One meteorite fragment of 32g was used to measure cosmogenic radionuclides using non-destructive high-resolution gamma spectrometry technique. Five radioisotopes such as Al-26, Na-22, Mn-54, Co-57 and Co-60 were detected

  11. On the measurement of cosmogenic nuclides in cometary materials

    International Nuclear Information System (INIS)

    Herzog, G.F.; Englert, P.A.J.; Reedy, R.C.; Nishiizumi, K.; Kohl, C.P.; Arnold, J.R.

    1989-01-01

    Determinations of the cosmogenic nuclide concentrations in cometary material will help to define the recent surface history of the comet and its exposure to cosmic rays. In particular, the rates for the removal or mixing of surface material could be studied, and any variations in cosmic-ray intensity implied by the data could be used to infer orbital changes during the last few million years. The measurement of the shorter-lived isotopes poses technical challenges that should be addressed now. The measurement of longer-lived isotopes will be straightforward provided that rates of mass loss are not too high. 46 refs., 2 figs

  12. Cosmogenic nuclide shielding corrections determined via MCNPX radiation transport and spallation cross sections

    Science.gov (United States)

    Argento, D.; Reedy, R. C.; Stone, J. O.

    2011-12-01

    Cosmogenic Nuclides (CNs) are a critical new tool for geomorphology, allowing researchers to date Earth surface events and measure process rates [1]. Prior to CNs, many of these events and processes had no absolute method for measurement and relied entirely on relative methods. Reliable absolute measurement methods impact research constraining ice age extents and provide important climatic data via well constrained erosion rates, etc. [2]. Continuing to improve CN methods is critical for these sciences. Significant progress has been made in the last two decades in refining the method and reducing analytic uncertainties [1,3]. CRONUS-Earth, a collaboration of cosmogenic nuclide researchers, has been developing calibration data and scaling methods to provide a self-consistent platform for use in interpreting nuclide concentration values into geologic data. However, several aspects of the radiation cascade have been exceedingly difficult to measure empirically with either accuracy or spatial extent. One such aspect is the angular distribution of secondary cosmic rays that are energetic enough to produce cosmogenic nuclides via spallation. Researchers studying the angular distribution of such cosmic rays have usually described the distribution as (cos(Θ))^m. Currently, the standard corrections, assume an m of 2.3, which is based on very sparse data sets with very limited spatial and altitude variation [1,4,5]. Researchers using CNs must know the production rate at the sample location, and then make corrections for the portion of the sky that is blocked by nearby topography. If the shielding correction model currently used is too simplistic, this introduces error into the final results. In this study, a Monte Carlo method radiation transport code, MCNPX is used to model the Galactic Cosmic Ray (GCR) radiation impinging on the upper atmosphere and tracks the resulting secondary particles through a model of the Earth's atmosphere. Angle and energy distributions are

  13. Cosmogenic neutron production at Daya Bay

    Science.gov (United States)

    An, F. P.; Balantekin, A. B.; Band, H. R.; Bishai, M.; Blyth, S.; Cao, D.; Cao, G. F.; Cao, J.; Chan, Y. L.; Chang, J. F.; Chang, Y.; Chen, H. S.; Chen, S. M.; Chen, Y.; Chen, Y. X.; Cheng, J.; Cheng, Z. K.; Cherwinka, J. J.; Chu, M. C.; Chukanov, A.; Cummings, J. P.; Ding, Y. Y.; Diwan, M. V.; Dolgareva, M.; Dove, J.; Dwyer, D. A.; Edwards, W. R.; Gill, R.; Gonchar, M.; Gong, G. H.; Gong, H.; Grassi, M.; Gu, W. Q.; Guo, L.; Guo, X. H.; Guo, Y. H.; Guo, Z.; Hackenburg, R. W.; Hans, S.; He, M.; Heeger, K. M.; Heng, Y. K.; Higuera, A.; Hsiung, Y. B.; Hu, B. Z.; Hu, T.; Huang, H. X.; Huang, X. T.; Huang, Y. B.; Huber, P.; Huo, W.; Hussain, G.; Jaffe, D. E.; Jen, K. L.; Ji, X. L.; Ji, X. P.; Jiao, J. B.; Johnson, R. A.; Jones, D.; Kang, L.; Kettell, S. H.; Khan, A.; Koerner, L. W.; Kohn, S.; Kramer, M.; Kwok, M. W.; Langford, T. J.; Lau, K.; Lebanowski, L.; Lee, J.; Lee, J. H. C.; Lei, R. T.; Leitner, R.; Leung, J. K. C.; Li, C.; Li, D. J.; Li, F.; Li, G. S.; Li, Q. J.; Li, S.; Li, S. C.; Li, W. D.; Li, X. N.; Li, X. Q.; Li, Y. F.; Li, Z. B.; Liang, H.; Lin, C. J.; Lin, G. L.; Lin, S.; Lin, S. K.; Lin, Y.-C.; Ling, J. J.; Link, J. M.; Littenberg, L.; Littlejohn, B. R.; Liu, J. C.; Liu, J. L.; Loh, C. W.; Lu, C.; Lu, H. Q.; Lu, J. S.; Luk, K. B.; Ma, X. B.; Ma, X. Y.; Ma, Y. Q.; Malyshkin, Y.; Martinez Caicedo, D. A.; McDonald, K. T.; McKeown, R. D.; Mitchell, I.; Nakajima, Y.; Napolitano, J.; Naumov, D.; Naumova, E.; Ochoa-Ricoux, J. P.; Olshevskiy, A.; Pan, H.-R.; Park, J.; Patton, S.; Pec, V.; Peng, J. C.; Pinsky, L.; Pun, C. S. J.; Qi, F. Z.; Qi, M.; Qian, X.; Qiu, R. M.; Raper, N.; Ren, J.; Rosero, R.; Roskovec, B.; Ruan, X. C.; Steiner, H.; Sun, J. L.; Tang, W.; Taychenachev, D.; Treskov, K.; Tsang, K. V.; Tse, W.-H.; Tull, C. E.; Viaux, N.; Viren, B.; Vorobel, V.; Wang, C. H.; Wang, M.; Wang, N. Y.; Wang, R. G.; Wang, W.; Wang, X.; Wang, Y. F.; Wang, Z.; Wang, Z.; Wang, Z. M.; Wei, H. Y.; Wen, L. J.; Whisnant, K.; White, C. G.; Wise, T.; Wong, H. L. H.; Wong, S. C. F.; Worcester, E.; Wu, C.-H.; Wu, Q.; Wu, W. J.; Xia, D. M.; Xia, J. K.; Xing, Z. Z.; Xu, J. L.; Xu, Y.; Xue, T.; Yang, C. G.; Yang, H.; Yang, L.; Yang, M. S.; Yang, M. T.; Yang, Y. Z.; Ye, M.; Ye, Z.; Yeh, M.; Young, B. L.; Yu, Z. Y.; Zeng, S.; Zhan, L.; Zhang, C.; Zhang, C. C.; Zhang, H. H.; Zhang, J. W.; Zhang, Q. M.; Zhang, R.; Zhang, X. T.; Zhang, Y. M.; Zhang, Y. M.; Zhang, Y. X.; Zhang, Z. J.; Zhang, Z. P.; Zhang, Z. Y.; Zhao, J.; Zhou, L.; Zhuang, H. L.; Zou, J. H.; Daya Bay Collaboration

    2018-03-01

    Neutrons produced by cosmic ray muons are an important background for underground experiments studying neutrino oscillations, neutrinoless double beta decay, dark matter, and other rare-event signals. A measurement of the neutron yield in the three different experimental halls of the Daya Bay Reactor Neutrino Experiment at varying depth is reported. The neutron yield in Daya Bay's liquid scintillator is measured to be Yn=(10.26 ±0.86 )×10-5 , (10.22 ±0.87 )×10-5 , and (17.03 ±1.22 )×10-5 μ-1 g-1 cm2 at depths of 250, 265, and 860 meters-water-equivalent. These results are compared to other measurements and the simulated neutron yield in Fluka and Geant4. A global fit including the Daya Bay measurements yields a power law coefficient of 0.77 ±0.03 for the dependence of the neutron yield on muon energy.

  14. Study of the cosmogenic activation in NaI(Tl) crystals within the ANAIS experiment

    Science.gov (United States)

    Villar, P.; Amaré, J.; Cebrián, S.; Coarasa, I.; García, E.; Martínez, M.; Oliván, M. A.; Ortigoza, Y.; Ortiz de Solórzano, A.; Puimedón, J.; Sarsa, M. L.; Villar, J. A.

    2018-03-01

    The direct detection of galactic dark matter particles requires ultra-low background conditions. NaI(Tl) crystals are applied in the search for these dark matter particles through their interactions in the detector by measuring the scintillation signal produced. The production of long-lived isotopes in materials due to the exposure to cosmic rays on Earth’s surface can be an hazard for these ultra-low background demanding experiments, typically performed underground. Therefore, production rates of cosmogenic isotopes in all the materials present in the experimental set-up, as well as the corresponding cosmic rays exposure history, must be both well-known in order to assess the relevance of this effect in the achievable sensitivity of a given experiment. Here, analysis of the cosmogenic studies developed from the ANAIS experiment NaI(Tl) detectors are presented. Installed inside a convenient shielding at the Canfranc Underground Laboratory just after finishing surface exposure to cosmic rays and thanks to the prompt data taking developed, identification and quantification of isotopes with half-lives of the order of tens of days were allowed, and thanks to the long-term operation of the detectors long-lived isotopes have been also identified and quantified. Main results for the activation yields of iodine and tellurium isotopes, 22Na, 113Sn, 109Cd, and tritium are presented in this work, together with the estimate of the production rates for their activation by cosmic nucleons while on Earth’s surface based on a selection of excitation functions over the entire energy range of cosmic nucleons.

  15. Cosmogenic Radionuclides as an Extension of the Neutron Monitor Era into the Past: Potential and Limitations

    Science.gov (United States)

    Beer, J.; McCracken, K. G.; Abreu, J.; Heikkilä, U.; Steinhilber, F.

    2013-06-01

    The cosmogenic radionuclides, 10Be, 14C and others, provide a record of the paleo-cosmic radiation that extends >10,000 years into the past. They are the only quantitative means at our disposal to study the heliosphere prior to the commencement of routine sunspot observations in the 17th century. The cosmogenic radionuclides are primarily produced by secondary neutrons generated by the galactic cosmic radiation, and can be regarded, in a sense, as providing an extrapolation of the neutron monitor era into the past. However, their characteristics are quite different from the man-made neutron monitor in several important respects: (1) they are sensitive to somewhat lower cosmic ray energies; (2) their temporal resolution is ˜1 to 2 years, being determined by the rapidity with which they are sequestered in ice, biological, or other archives; (3) the statistical precision for annual data is very poor (˜19%); however it is quite adequate (˜5% for 22-year averages) to study the large variations (±40%) that have occurred in the paleo-cosmic ray record in the past between grand solar minima and maxima. The data contains "noise" caused by local meteorological effects, and longer-term climate effects, and the use of principal component analysis to separate these "system" effects from production effects is outlined. The concentrations of 10Be decreased by a factor of two at the commencement of Holocene, the present-day "interglacial", due to a 100% increase in the ice accumulation rates in polar regions. The use of the 10Be flux to study heliospheric properties during the last glacial is discussed briefly.

  16. A proposal of comparative Maunder minimum cosmogenic isotope measurements

    International Nuclear Information System (INIS)

    Attolini, M.R.; Nanni, T.; Galli, M.; Povinec, P.

    1989-01-01

    There are at present contraddictory conclusions about solar activity and cosmogenic isotope production variation during Maunder Minimum. The interaction of solar wind with galactic cosmic rays, the dynamic behaviour of the Sun either as a system having an internal clock, and/or as a forced non linear system, are important aspects that can shed new light on solar physics, the Earth-Sun relationship and the climatic variation. An essential progress in the matter might be made by clarifying the cosmogenic isotope production during the mentioned interval. As it seems that during Maunder Minimum the Be10 production oscillates of about a factor of two, the authors have also to expect short scale enhanced variations in tree rings radiocarbon concentrations for the same interval. It is therefore highly desirable that for the same interval, that the authors would identify with 1640-1720 AD, detailed concentration measurements both of Be10 (in dated polar ice in addition to those of Beer et al.) and of tree ring radiocarbon, be made with cross-checking, in samples of different latitudes, longitudes and within short and large distance of the sea. The samples could be taken, as for example in samples from the central Mediterranean region, in the Baltic region and in other sites from central Europe and Asia

  17. Assessment of {sup 7}Be content in precipitation in a South American semi-arid environment

    Energy Technology Data Exchange (ETDEWEB)

    Juri Ayub, J., E-mail: jjuri@unsl.edu.ar [Grupo de Estudios Ambientales, Instituto de Matematica Aplicada San Luis, Universidad Nacional de San Luis/CCT-San Luis-CONICET, San Luis (Argentina); LARA, Laboratorio de Radioecologia, Instituto de Fisica, Universidade Federal Fluminense, Niteroi, RJ (Brazil); Lohaiza, F.; Velasco, H.; Rizzotto, M. [Grupo de Estudios Ambientales, Instituto de Matematica Aplicada San Luis, Universidad Nacional de San Luis/CCT-San Luis-CONICET, San Luis (Argentina); Di Gregorio, D.; Huck, H. [Departamento de Fisica, Comision Nacional de Energia Atomica, Buenos Aires (Argentina); Escuela de Ciencia y Tecnologia, Universidad Nacional de San Martin, Buenos Aires (Argentina)

    2012-12-15

    There are two naturally occurring radiogenic isotopes of beryllium, {sup 7}Be and {sup 10}Be. These are produced when cosmic radiation interacts with oxygen and nitrogen in the atmosphere. After production, these radionuclides are input to ecosystems through wet and dry deposition. In recent years {sup 7}Be and {sup 10}Be have proved to be powerful tools for studying dynamic processes that occur on the surface of the earth. We measured the {sup 7}Be content in precipitation at a semiarid location in central Argentina. From November 2006 to March 2009, 68 precipitation events were collected. Measured {sup 7}Be content ranged from 0.7 {+-} 0.4 Bq L{sup -1} to 3.2 {+-} 0.7 Bq L{sup -1}, with a mean of 1.7 Bq L{sup -1} {+-} 0.6 Bq L{sup -1}. Beryllium-7 content of rainfall did not show clear relationships with amount of rainfall (mm), mean intensity (mm h{sup -1}) or duration (h{sup -1}), or elapsed time between events (day). The general results indicate that for the typical range of precipitation there was no atmospheric washout and that the reload of the atmosphere is not a relevant factor, but when the amount of precipitation is very high washout may occur. On the other hand, when the {sup 7}Be content was measured during single rain events, a high content of this radionuclide was found to be associated with very low rainfall intensity ( Almost-Equal-To 3 mm h{sup -1}), this suggests that rain intensity could affect the {sup 7}Be content. Using all data, a good linear relationship between {sup 7}Be deposition and rain magnitude was obtained (r{sup 2} = 0.82, p < 0.0001). Because of this, the slope of this linear regression equation may be applied as a tool for tracing environmental processes that affect the surface of the earth. We can do this by directly estimating erosion/sedimentation processes using {sup 7}Be or by estimating the input of {sup 10}Be in the environment with the aim to evaluate land degradation phenomena. -- Highlights: Black

  18. Assessment of 7Be content in precipitation in a South American semi-arid environment

    International Nuclear Information System (INIS)

    Juri Ayub, J.; Lohaiza, F.; Velasco, H.; Rizzotto, M.; Di Gregorio, D.; Huck, H.

    2012-01-01

    There are two naturally occurring radiogenic isotopes of beryllium, 7 Be and 10 Be. These are produced when cosmic radiation interacts with oxygen and nitrogen in the atmosphere. After production, these radionuclides are input to ecosystems through wet and dry deposition. In recent years 7 Be and 10 Be have proved to be powerful tools for studying dynamic processes that occur on the surface of the earth. We measured the 7 Be content in precipitation at a semiarid location in central Argentina. From November 2006 to March 2009, 68 precipitation events were collected. Measured 7 Be content ranged from 0.7 ± 0.4 Bq L −1 to 3.2 ± 0.7 Bq L −1 , with a mean of 1.7 Bq L −1 ± 0.6 Bq L −1 . Beryllium-7 content of rainfall did not show clear relationships with amount of rainfall (mm), mean intensity (mm h −1 ) or duration (h −1 ), or elapsed time between events (day). The general results indicate that for the typical range of precipitation there was no atmospheric washout and that the reload of the atmosphere is not a relevant factor, but when the amount of precipitation is very high washout may occur. On the other hand, when the 7 Be content was measured during single rain events, a high content of this radionuclide was found to be associated with very low rainfall intensity (≈ 3 mm h −1 ), this suggests that rain intensity could affect the 7 Be content. Using all data, a good linear relationship between 7 Be deposition and rain magnitude was obtained (r 2 = 0.82, p 7 Be or by estimating the input of 10 Be in the environment with the aim to evaluate land degradation phenomena. -- Highlights: ► 7 Be in precipitation was measured at a semiarid location in central Argentina. ► No atmospheric washout was observed except for one high precipitation event. ► Wet deposition of 7 Be was linearly correlated with precipitation. ► This relationship may be applied as a tool for assessing environmental processes. ► The latter includes natural processes as

  19. Calibration of cosmogenic 3He and 10Be production rates in the High Tropics

    Science.gov (United States)

    Blard, Pierre-Henri; Martin, Léo; Lavé, Jérôme; Charreau, Julien; Condom, Thomas; Lupker, Maarten; Braucher, Régis; Bourlès, Didier

    2014-05-01

    It is critical to refine both the accuracy and the precision of the in situ cosmogenic dating tool, especially for establishing reliable glacial chronologies that can be compared to other paleoclimatic records. Recent cross-calibrations of cosmogenic 3He in pyroxene and 10Be in quartz [1, 2] showed that, both at low (1300 m) and high elevation (4850 m), the 3He/10Be production ratio was probably ~40% higher than the value of ~23 initially defined in the 90's. This recent update is consistent with the last independent determinations of the sea level high latitude production rates of 10Be and 3He, that are about 4 and 125 at.g-1.yr-1, respectively [e.g. 3, 4]. However, major questions remain about these production rates at high elevation, notably because existing calibration sites for both 3He and 10Be are scarce above 2000 m. It is thus crucial to produce new high precision calibration data at high elevation. Here we report cosmogenic 10Be data from boulders sampled on a glacial fan located at 3800 m in the Central Altiplano (Bolivia), whose age is independently constrained by stratigraphic correlations and radiocarbon dating at ca. 16 ka. These data can be used to calibrate the production rate of 10Be at high elevation, in the Tropics. After scaling to sea level and high latitude, these data yield a sea level high latitude P10 ranging from 3.8 to 4.2 at.g-1.yr-1, depending on the used scaling scheme. These new calibration data are in good agreement with recent absolute and cross-calibration of 3He in pyroxenes and 10Be in quartz, from dacitic moraines located at 4850 m in the Southern Altiplano (22° S, Tropical Andes) [2,5]. The so-obtained 3He/10Be production ratio of 33.3±0.9 (1σ) combined with an absolute 3He production rate locally calibrated in the Central Altiplano, at 3800 m, indeed yielded a sea level high latitude P10 ranging from 3.7±0.2 to 4.1±0.2 at.g-1.yr-1, depending on the scaling scheme [2,5]. These values are also consistent with the 10Be

  20. Modelling the observed vertical transport of {sup 7}Be in specific soils with advection dispersion model

    Energy Technology Data Exchange (ETDEWEB)

    Torres Astorga, Romina; Velasco, Hugo; Valladares, Diego L.; Lohaiza, Flavia; Ayub, Jimena Juri; Rizzotto, Marcos [Grupo de Estudios Ambientales. Instituto de Matematica Aplicada San Luis - Universidad Nacional de San Luis - CONICET, San Luis (Argentina)

    2014-07-01

    {sup 7}Be is a short-lived environmental radionuclide, produced in the upper atmosphere by spallation of nitrogen and oxygen by cosmic rays. After of the production by the nuclear reaction, {sup 7}Be diffuses through the atmosphere until it attaches to atmospheric aerosols. Subsequently, it is deposited on the earth surface mainly as wet fallout. The main physical processes which transport {sup 7}Be in soil are diffusion and advection by water. Migration parameters and measurements confirm that sorption is the main physical process, which confines {sup 7}Be concentration to soil surface. The literature data show that in soils, {sup 7}Be is concentrated near the surface (0-2 cm) as it is adsorbed onto clay minerals after its deposition on the soil surface and does not penetrate deeper into soils due to its short half-life. The maximum mass activity density of {sup 7}Be is found at the point of input of the radionuclide, i.e. at the surface of the soil column, showing a exponential distribution profile typical of a purely diffusive transport. Many studies applying the advection dispersion models have been reported in the literature in order to modelling the transport of {sup 137}Cs in soils. On them, the models are used to achieve information of the mechanisms that govern the transport, i. e. the model is used to explain the soil profile of radionuclide. The effective dispersion coefficient and the apparent advection velocity of radionuclide in soil are also obtained by fitting the analytical solution of the model equation to measured depth distributions of the radionuclide. In this work, the advective dispersive transport model with linear sorption is used to analyze the vertical migration process of {sup 7}Be in soils of undisturbed or reference sites. The deposition history is approximated by pulse-like input functions and time dependent analytical solution of equation model is obtained. The values of dispersion coefficient and apparent advection velocity obtained

  1. Cosmogenic He and Ne in chondrules from clastic matrix and a lithic clast of Murchison: No pre-irradiation by the early sun

    Science.gov (United States)

    Riebe, My E. I.; Huber, Liliane; Metzler, Knut; Busemann, Henner; Luginbuehl, Stefanie M.; Meier, Matthias M. M.; Maden, Colin; Wieler, Rainer

    2017-09-01

    Whether or not some meteorites retain a record of irradiation by a large flux of energetic particles from the early sun in the form of excesses of cosmic-ray produced noble gases in individual crystals or single chondrules is a topic of ongoing debate. Here, we present He and Ne isotopic data for individual chondrules in Murchison, a chondritic regolith breccia of the CM group. We separated 27 chondrules from a clastic matrix portion and 26 chondrules from an adjacent single so-called "primary accretionary rock" (Metzler et al., 1992). All chondrules from the primary rock fragment are expected to share a common irradiation history, whereas chondrules from the clastic matrix were stirred in the regolith independently of each other. All "primary rock chondrules" and 23 of the "matrix chondrules" have very similar concentrations of cosmogenic 3He and 21Ne, corresponding to a cosmic-ray exposure age to galactic cosmic rays (GCR) of ∼1.3-1.9 Ma, in the range of Murchison's meteoroid exposure age determined with cosmogenic radionuclides. Four clastic matrix chondrules contain excesses of cosmogenic 3He and 21Ne, corresponding to nominal 4π exposure ages of ∼4-∼29 Ma, with a Ne isotopic composition as expected for production by GCR. If the fraction of excess cosmogenic gas bearing chondrules in the primary rock and clastic matrix were the same, we would expect this result with a statistical probability of only 0.5 - 2.7%. Therefore, the exposure age distributions for Murchison chondrules in primary rock and clastic matrix are very likely different. Such a difference is expected if the excess cosmogenic gas was acquired by some of the matrix chondrules in the regolith, but not if chondrules were irradiated in the solar nebula by the early sun before they accreted on the Murchison parent body. Therefore, Murchison does not provide evidence for irradiation by a high fluence of energetic particles from the early sun. By inference, this statement likely holds for the

  2. Concentration of 7Be in the lower atmosphere and fallout rate in Tokai

    International Nuclear Information System (INIS)

    Amano, Hikaru; Kasai, Atsushi

    1981-01-01

    Beryllium-7, cosmic ray produced radioactivity, its monthly average concentration in the lower atmosphere and monthly fallout rate were measured in Tokai, Japan. Then, the monthly variations were compared with those of fission products due to nuclear detonations in the atmosphere. The concentration of 7 Be in the lower atmosphere ranged from 0.5 x 10 -1 pCi/m 3 to 2.5 x 10 -1 pCi/m 3 in Tokai between the observed period, 1975 - 1977. The fallout rate of 7 Be vibrated widely, its range was from the detection limits to 1.2 x 10 4 pCi/m 2 . The monthly variations were not always the same with variations of the fission products. Fallout rate of 7 Be depended on the rain strongly. The concentration of 7 Be in the rain was measured, too. Then the range was from 9.2 pCi/l to 1.9 x 10 2 pCi/l between the observed period 1976.9 - 1977.2. (author)

  3. 7Be content and its seasonal regulation in the ground air around Hangzhou area

    International Nuclear Information System (INIS)

    Jiang Rangrong

    1995-01-01

    In twice investigations around Hangzhou, it is indicated that 7 Be concentration in the ground air is averagely 5.9 mBq/m 3 which is 130% higher than that in Germany reported by UNSCEAR. The highest level is in autumn-winter over a year reaching 7.7 mBq/m 3 ; the next is in spring reaching 6.2 mBq/m 3 ; the middle is 5.7 mBq/m 3 in early summer approaching to the yearly average level; and the lowest in a year is in summer-autumn that is 3.8 mBq/m 3 . It presents a decreasing regulation from autumn-winter to summer-autumn of the next year, and is basically consistent with the seasonal variation of the rainfall in Hangzhou area, but does not present the variation reported by UNSCEAR that it was the highest in spring and the lowest in late autumn basing on 7 Be falling down from the stratosphere. It shows that the process of rainfall is the main reason effecting 7 Be content in the air. Comparing to 222 Rn, the annual absorption dose produced by 7 Be can be neglected

  4. Estimation of production rates for in-situ cosmogenic isotopes and application to surface exposure dating: certitudes and uncertainties

    International Nuclear Information System (INIS)

    Graham, I.J.

    1996-01-01

    Cosmogenic nuclides, produced in-situ in rocks by the action of cosmic rays on target nuclei, are increasingly being employed by earth scientists in a wide variety of applications. For example, surface exposure dating is used to determine erosion rates, the age of debris flows, alluvial fans, volcanic eruptions, meteoritic impact craters, and glacial deposits, and the timing of recent movement along faults and tectonic uplift. The technique can thus play a vital role in the study of potential hazards from geological processes, by establishing recurrence intervals between them, and establish chronologies and periodicities for major paleoclimatic events. Before surface exposure dating methods using cosmogenic isotopes can be applied even more widely, production rates of the main nuclides of interest must be better known, and their temporal and spatial variabilities determined. This paper summarises the present state of knowledge on production rates of the currently most useful nuclides ( 10 Be, 26 Al, 36 Cl, 14 C, 3 He and 21 Ne), discusses the main areas of concern, and makes suggestions for future improvement. (author). 83 refs., 7 tabs., 11 figs

  5. Evidence for an increase in cosmogenic 10Be during a geomagnetic reversal

    International Nuclear Information System (INIS)

    Raisbeck, G.M.; Yiou, F.; Bourles, D.

    1985-01-01

    The authors report evidence in marine sediments for an increase in cosmogenic 10 Be production in the Earth's atmosphere during the Brunhes-Matuyama reversal 730,000 yr ago. In addition to confirming an increase in cosmogenic isotope production, the results provide information on the magnitude and duration of the geomagnetic intensity decrease during such an event, and the depth at which remanent magnetism is acquired in marine sediments. (author)

  6. Landscape Evolution Mechanisms in Gale Crater from In-Situ Measurement of Cosmogenic Noble Gas Isotopes

    Science.gov (United States)

    Martin, P.; Farley, K. A.; Mahaffy, P. R.; Malespin, C.; Vasconcelos, P. M.

    2017-12-01

    The Sample Analysis at Mars (SAM) instrument onboard the Curiosity rover can measure the noble gas isotopes contained in drilled rock samples on Mars by heating these samples to 930°C. In combination with bulk chemistry measured by the Alpha Particle X-ray Spectrometer (APXS), cosmogenic nuclide production rates can be determined and an exposure age may be calculated. Three cosmogenic nuclides are measured: 3He, and 21Ne, which are produced via spallation of mainly O, Mg, Si, and Al (held mostly in detrital grains); and 36Ar, which is produced from neutron capture of 35Cl (held mostly in secondary materials). To date, three samples have been measured: Cumberland (CB), Windjana (WJ), and Mojave 2 (MJ2). CB yielded 3He, 21Ne, and 36Ar ages of 72 ± 15, 84 ± 28, and 79 ± 24 Ma, respectively [Farley et al., 2014]. Two aliquots of WJ gave error-weighted mean ages of 30 ± 27 Ma (3He), 54 ± 19 Ma (21Ne), and 63 ± 84 Ma (36Ar) [Vasconcelos et al., 2016]. These relatively young ages were interpreted to suggest that a scarp-retreat mechanism is responsible for erosion at both the CB and WJ localities. The most recent measurements on MJ2 do not include the 21Ne isotope because of an instrument issue at this mass. 3He observed in MJ2 is the highest of any sample yet measured, suggesting an exposure age of approximately 1 Ga. In contrast, the calculated exposure age from 36Ar appears to be less than 100 Ma (despite a high uncertainty due to isobaric H35Cl). This discrepancy could be explained by 1) a contribution of extraterrestrial 3He from interplanetary dust or meteoritic fragments, or 2) approximately 1 Ga of prior exposure to the detrital grains. In the latter case 36Ar accumulates only after the Cl-bearing secondary minerals are formed and exposed at the surface. In either scenario the 36Ar measurement provides the better estimate of the recent exposure history. The young upper limit for 36Ar at MJ2 is consistent with the scarp-retreat mechanism observed at CB and

  7. Cosmic-ray interactions and dating of meteorite stranding surfaces with cosmogenic nuclides

    Energy Technology Data Exchange (ETDEWEB)

    Reedy, R.C.

    1988-01-01

    A wide variety of products from cosmic-ray interactions have been measured in terrestrial or extraterrestrial samples. These ''cosmogenic'' products include radiation damage tracks and rare nuclides that are made by nuclear reactions. They often have been used to determine the fluxes and composition of cosmic-ray particles in the past, but they are usually used to study the history of the ''target'' (such as the time period that it was exposed to cosmic-ray particles). Products made by both the high-energy galactic cosmic rays and energetic particles emitted irregularly from the Sun have been extensively studied. Some of these cosmogenic products, especially nuclides, have been or can be applied to studies of Antarctic meteorite stranding surfaces, the ice surfaces in Antarctica where meteorites have been found. Cosmogenic nuclides studied in samples from Antarctica and reported by others elsewhere in this volume include those in meteorites, especially radionuclides used to determine terrestrial ages, and those made in situ in terrestrial rocks. Cosmogenic nuclides made in the Earth's atmosphere or brought in with cosmic dust have also been studied in polar ice, and it should also be possible to measure nuclides made in situ in ice. As an introduction to cosmogenic nuclides and their applications, cosmic rays and their interactions will be presented below and production systematics of cosmogenic nuclides in these various media will be discussed later. 20 refs., 2 tabs.

  8. Cosmic-ray interactions and dating of meteorite stranding surfaces with cosmogenic nuclides

    International Nuclear Information System (INIS)

    Reedy, R.C.

    1988-01-01

    A wide variety of products from cosmic-ray interactions have been measured in terrestrial or extraterrestrial samples. These ''cosmogenic'' products include radiation damage tracks and rare nuclides that are made by nuclear reactions. They often have been used to determine the fluxes and composition of cosmic-ray particles in the past, but they are usually used to study the history of the ''target'' (such as the time period that it was exposed to cosmic-ray particles). Products made by both the high-energy galactic cosmic rays and energetic particles emitted irregularly from the Sun have been extensively studied. Some of these cosmogenic products, especially nuclides, have been or can be applied to studies of Antarctic meteorite stranding surfaces, the ice surfaces in Antarctica where meteorites have been found. Cosmogenic nuclides studied in samples from Antarctica and reported by others elsewhere in this volume include those in meteorites, especially radionuclides used to determine terrestrial ages, and those made in situ in terrestrial rocks. Cosmogenic nuclides made in the Earth's atmosphere or brought in with cosmic dust have also been studied in polar ice, and it should also be possible to measure nuclides made in situ in ice. As an introduction to cosmogenic nuclides and their applications, cosmic rays and their interactions will be presented below and production systematics of cosmogenic nuclides in these various media will be discussed later. 20 refs., 2 tabs

  9. Determination of Cross-Sections of Fast-Muon-Induced Reactions to Cosmogenic Radionuclides

    CERN Multimedia

    Hagner, T; Heisinger, B; Niedermayer, M; Nolte, E; Oberauer, L; Schonert, S; Kubik, P W

    2002-01-01

    %NA54 %title\\\\ \\\\We propose to measure cross-sections for fast muon-induced production of radionuclides. Firstly to study the contribution of fast-muon-induced reactions to the in-situ production of cosmogenic radionuclides in the lithosphere. Concrete is used to simulate the rock and to generate a secondary particle shower. The reaction channels to be measured are: C to $^{10}$Be, O to $^{10}$Be and $^{14}$C, Si to $^{26}$Al, S to $^{26}$Al, Ca to $^{36}$Cl, Fe to $^{53}$Mn and $^{205}$Tl to $^{205}$Pb. The energy dependent cross-section can be described by one single parameter $\\sigma_0$ and the energy dependence $\\rm\\overline{E}^{0.7}$ on the mean energy $\\rm\\overline{E}$. The irradiations of the targets is done at CERN. The produced radionuclides are measured by accelerator mass spectrometry in Munich and Zurich.\\\\ \\\\Secondly, muon induced signals can be a major source of background in experiments with low event rates located deep underground. We intent to study the produced radioactivity by fast-muon-ind...

  10. The 10B (7Li, 7Be)10Be charge-exchange reaction

    International Nuclear Information System (INIS)

    Etchegoyen, A.

    1987-01-01

    It is analysed the mechanisms: direct charge-exchange through the two-body residual force (Q opt ∼ 0.2 MeV, which is close to the reaction Q-value of - 1,42 MeV); and single-Nucleon Knock-on exchange (SNKE) due to the intereacting nucleons being undistinguishable. These mechanisms are analysed in detail for producing 10 B ( 7 Li, 7 Be) 10 Be reaction. The experience was carried out at the Tandar Laboratory using conventional electronics. The elastic scattering was simultaneously measured in order to obtain an optical model parameter set. (M.C.K.) [pt

  11. 7Be(p, γ)8B and the high-energy solar neutrino flux

    International Nuclear Information System (INIS)

    Csoto, A.

    1997-01-01

    Despite thirty years of extensive experimental and theoretical work, the predicted solar neutrino flux is still in sharp disagreement with measurements. The solar neutrino measurements strongly suggest that the problem cannot be solved within the standard electroweak and astrophysical theories. Thus, the solar neutrino problem constitutes the strongest evidence for physics beyond the Standard Model. Whatever the solution of the solar neutrino problem turns out to be, it is of paramount importance that the input parameters of the underlying electroweak and solar theories rest upon solid ground. The most uncertain nuclear input parameter in standard solar models is the low-energy 7 Be(p, γ) 8 B radiative capture cross section. This reaction produces 8 B in the Sun, whose β + decay is the main source of the high-energy solar neutrinos. Here, the importance of the 7 Be(p, γ) 8 B reaction in predicting the high energy solar neutrino flux is discussed. The author presents a microscopic eight-body model and a potential model for the calculation of the 7 Be(p, γ) 8 B cross section

  12. Rates of surface lowering and landscape development in southern South Africa: a cosmogenic view

    Science.gov (United States)

    Richardson, Janet; Vanacker, Veerle; Lang, Andreas; Hodgson, David

    2016-04-01

    The landscape of southern South Africa is characterised by large-scale erosion surfaces, including extensive pediments and multiple strath terraces, which document discordant river evolution through resistant quarzitic lithologies of the Cape Fold Belt (CFB). The timing and rate of erosion is poorly constrained. New cosmogenic ages from surfaces in South Africa are presented using in situ produced 10Be. Strath terraces in deeply incised rivers at two sites within the CFB indicate slow rates of erosion (1.54 - 11.79 m/Ma), which are some of the lowest rates recorded globally. Four pediment surfaces and a depth profile of the thickest pediment were also dated, and the results indicate that there are low rates of surface lowering on the pediments (0.44 - 1.24 m/Ma). The pediments are long-lived features (minimum exposure ages of 0.47 - 1.09 Ma), and are now deeply dissected. Given the minimum exposure ages, calculated river incision rates (42- 203 m/Ma) suggest that after a long period of geomorphic stability during pediment formation there was a discrete phase of increased geomorphic activity. The calculated minimum exposure ages are considered dubious because: 1) known rates of surrounding river incision (published and ours); 2) the climate conditions and time necessary for ferricrete formation on the pediment surfaces and; 3) the deeply incised catchments in the CFB on which the pediments sit, which all point to the pediments being much older. The pediments are fossilised remnants of a much larger geomorphic surface that formed after the main phase of exhumation in southern Africa. They form a store of sediment that currently sit above the surrounding rivers that have some of the lowest erosion rates in the world. These results indicate that steep topography can prevail even in areas of low erosion and tectonic quiescence, and that whilst cosmogenic dating of landscapes is an exciting development in earth sciences, care is needed especially in ancient settings. We

  13. Erosion of mountain plateaus along Sognefjord, Norway, constrained by cosmogenic nuclides

    DEFF Research Database (Denmark)

    Andersen, Jane Lund; Egholm, David Lundbek; Knudsen, Mads Faurschou

    –climate–erosion) hypothesis. Journal of Geodynamics 47(2), 72-95, 2009. Steer et al. Bimodal Plio-Quaternary glacial erosion of fjords and low-relief surfaces in Scandinavia. Na- ture Geoscience 5(9), 635-639, 2012. Egholm et al. The periglacial engine of mountain erosion – Part 2: Modelling large-scale landscape evolu- tion......Norway is famous for its deeply incised, steep-sided fjords, carved out by glacial erosion. The high relief of the fjords stands in contrast to the extensive areas of relatively low relief found between the fjords. The origin and development of these low-relief areas remain debated. The classical...... instead to a significant impact of glacial and periglacial erosion processes on the long-term development of the low-relief surfaces (Egholm et al. 2015). Here, we present a large new dataset of in-situ produced cosmogenic 10Be and 26Al in bedrock and boulders from the high, flat summit surfaces along...

  14. Possible cosmogenic neutrino constraints on Planck-scale Lorentz violation

    International Nuclear Information System (INIS)

    Mattingly, David M.; Maccione, Luca; Galaverni, Matteo; Liberati, Stefano; Sigl, Günter

    2010-01-01

    We study, within an effective field theory framework, O(E 2 M Pl 2 ) Planck-scale suppressed Lorentz invariance violation (LV) effects in the neutrino sector, whose size we parameterize by a dimensionless parameter η ν . We find deviations from predictions of Lorentz invariant physics in the cosmogenic neutrino spectrum. For positive O(1) coefficients no neutrino will survive above 10 19 eV. The existence of this cutoff generates a bump in the neutrino spectrum at energies of 10 17 eV. Although at present no constraint can be cast, as current experiments do not have enough sensitivity to detect ultra-high-energy neutrinos, we show that experiments in construction or being planned have the potential to cast limits as strong as η ν ∼ −4 on the neutrino LV parameter, depending on how LV is distributed among neutrino mass states. Constraints on η ν < 0 can in principle be obtained with this strategy, but they require a more detailed modeling of how LV affects the neutrino sector

  15. Possible cosmogenic neutrino constraints on Planck-scale Lorentz violation

    Energy Technology Data Exchange (ETDEWEB)

    Mattingly, David M. [New Hamshire Univ., Durham, NH (United States); Maccione, Luca [DESY Hamburg (Germany). Theory Group; Galaverni, Matteo [INAF-IASF Bologna (Italy); Liberati, Stefano [INFN, Trieste (Italy); SISSA, Trieste (Italy); Sigl, Guenter [Hamburg Univ. (Germany). II. Inst. fuer Theoretische Physik

    2009-11-15

    We study, within an effective field theory framework, O(E{sup 2}/M{sup 2}{sub Pl}) Planck-scale suppressed Lorentz invariance violation (LV) effects in the neutrino sector, whose size we parameterize by a dimensionless parameter {eta}{sub {nu}}. We find deviations from predictions of Lorentz invariant physics in the cosmogenic neutrino spectrum. For positive O(1) coefficients no neutrino will survive above 10{sup 19} eV. The existence of this cutoff generates a bump in the neutrino spectrum at energies of 10{sup 17} eV. Although at present no constraint can be cast, as current experiments do not have enough sensitivity to detect ultra-high-energy neutrinos, we show that experiments in construction or being planned have the potential to cast limits as strong as {eta}{sub {nu}}

  16. Surface exposure history using in-situ cosmogenic 10Be, 26Al and 36Cl - applications to the Australian environment

    International Nuclear Information System (INIS)

    Fink, D.

    1999-01-01

    Production of the long-lived cosmogenic radionuclides, 10 Be (T 1/2 =1.5Ma), 26 Al (0.7Ma) and 36 Cl (0.3Ma), is dominated by the interaction of cosmic-rays with the upper atmosphere. They are also produced in exposed surface rocks and within the first meter or so of the Earth's crust. This is called in-situ production and although only a million atoms or so of 10 Be are produced within a ten thousand year exposure period per gram of surface rock, the technique of Accelerator Mass Spectrometry (AMS) can be applied to measure this tell-tale signal. The build-up over time of these radionuclides can be utilised as radiometric clocks to elucidate the exposure history of geomorphic formations and surfaces that have experienced some event or process that delivers previously unexposed material to cosmic-ray irradiation. Hence the reconstruction of glacial chronologies (ie time a bedrock surface was uncovered by ice retreat, or deposition age of glacial moraines), development of raised river terraces and paleo-beach ridges, age of meteorite impact craters and volcanic eruptions have been addressed with the in-situ method. Moreover, geomorphological processes of landscape evolution such as surface erosion rates, continental weathering, sediment transport and deposition, uplift rates can also be studied. The in-situ method is described along with examples of cosmogenic dating projects at ANSTO. It is estimated that it works best over the time period from 5 ka to 5 Ma and can identify erosion rates ranging from 0.1 to 10 mm/ka

  17. Low-energy behavior of the 3He(α,γ)7Be cross section

    International Nuclear Information System (INIS)

    Osborne, J.L.; Barnes, C.A.; Kavanagh, R.W.; Kremer, R.M.; Mathews, G.J.; Zyskind, J.L.; Parker, P.D.; California Inst. of Tech., Pasadena; Howard, A.J.; California Inst. of Tech., Pasadena

    1984-01-01

    Cross sections for the 3 He(α,γ) 7 Be reaction have been measured at several energies from Esub(c.m.)=165 to 1169 keV by counting prompt γ-rays from a windowless, differentially pumped, recirculating, 3 He gas target. The cross-section factor S 34 (Esub(c.m.)) and branching ratio γ 1 /γ 0 were determined at each energy. Cross sections were also measured at Esub(c.m.)=947 and 1255 keV by counting the γ-rays from the 7 Be produced in a 3 He gas cell with a Ni entrance foil. Combining the results of these two independent experiments yields a zero-energy intercept for the cross-section factor of S 34 (O) = 0.53+-0.03 keV x b. The relationship between these measurements and serveral theoretical calculations, and the import of the extrapolated cross section for the solar-neutrino problem are discussed. (orig.)

  18. Survey on Cosmogenic 26Al in Lewis Cliff Meteorites

    Science.gov (United States)

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

    1992-07-01

    INTRODUCTION: We have embarked upon a ^26Al gamma-ray survey of meteorites selected from about 2000 samples recently recovered from the Lewis Cliff Ice Fields (84 degrees 18'S/161 degrees 20'E). Due to its 705-ka half-life ^26Al can be used for estimating terrestrial ages and thus contribute to further characterization of Antarctic meteorites in addition to their classification and thermoluminescence (TL) properties. The ^26Al survey is also useful for identifying meteorites with unusual exposure histories, which merit additional measurements of cosmogenic radionuclides (by AMS) and noble gases. In addition, it provides clues on possible pairings. METHOD: Low-level gamma-ray spectroscopy is well suited for ^26Al survey work, since bulk meteorite samples can be measured routinely and nondestructively without any previous sample preparation. The required size of the samples (30-500 g) makes the method relatively independent of depth effects and compositional inhomogeneities. The use of a high-resolution GeLi detector also allows the determination of the natural ^40K activity and thus the K content of the samples, which can be used as an additional pairing criterion for ordinary chondrites. Also ^137Cs, a fall-out surface contamination [1], is simultaneously measured; low values may be characteristic for meteorites recently fallen or released from the ablating ice. For the detector an efficiency calibration curve has been made that adequately accounts for differences in size and shape of the meteorite samples. RESULTS and DISCUSSION: TERRESTRIAL AGES: So far, we have measured over 30 Lewis Cliff equilibrated H and L chondrites, collected from widely differing locations. Normalized to L-chondrite composition, the ^26Al contents range from 27 to 110 dpm/kg with peaks around 43 and 53 dpm/kg. This bimodal ^26Al distribution is reminiscent of that observed for Allan Hills ordinary chondrites [2]. Tentative terrestrial ages, calculated on the basis of ^26Al saturation

  19. Measurements of the neutron-induced reactions on 7Be with CRIB by the Trojan Horse method

    Science.gov (United States)

    Hayakawa, S.; Abe, K.; Beliuskina, O.; Cha, S. M.; Chae, K. Y.; Cherubini, S.; Figuera, P.; Ge, Z.; Gulino, M.; Hu, J.; Inoue, A.; Iwasa, N.; Kahl, D.; Kim, A.; Kim, D. H.; Kiss, G.; Kubono, S.; La Cognata, M.; La Commara, M.; Lamia, L.; Lattuada, M.; Lee, E. J.; Moon, J. Y.; Palmerini, S.; Parascandolo, C.; Park, S. Y.; Pierroutsakou, D.; Pizzone, R. G.; Rapisarda, G. G.; Romano, S.; Shimizu, H.; Spitaleri, C.; Tang, X. D.; Trippella, O.; Tumino, A.; , P., Vi; Yamaguchi, H.; Yang, L.; Zhang, N. T.

    2018-04-01

    The cosmological 7Li problem has been one of the big issues left in the standard Big-Bang nucleosynthesis (BBN) model. In order to determine the radiogenic 7Li abundance by the BBN, it is important to know the production and the destruction rate of 7Be rather than 7Li itself. We performed indirect measurements of the relevant neutron-induced reactions 7Be(n, p)7Li and 7Be(n, α)4He simultaneously by the Trojan Horse Method (THM) via the three-body reactions 7Be(d,7Lip)1H and 7Be(d, αα)1H. A 7Be radioactive-isotope (RI) beam at 3.16 MeV/u was produced at Center-for-Nuclear-Study RI Beam (CRIB) separator. The Q-value spectra shows the evidence of the three-body channels of interest. We confirmed that the THM was applicable to the present measurements by the momentum distributions of the spectator proton. Preliminary excitation functions are roughly consistent with the previous studies, moreover providing new data in the BBN energy range, and suggesting that new information about the 7Be(n, p1)7Li* contribution may be obtained by carrying out a further data analysis.

  20. The Fourier analysis applied to the relationship between (7)Be activity in the Serbian atmosphere and meteorological parameters.

    Science.gov (United States)

    Rajačić, M M; Todorović, D J; Krneta Nikolić, J D; Janković, M M; Djurdjević, V S

    2016-09-01

    Air sample monitoring in Serbia, Belgrade started in the 1960s, while (7)Be activity in air and total (dry and wet) deposition has been monitored for the last 22 years by the Environment and Radiation Protection Department of the Institute for Nuclear Sciences, Vinca. Using this data collection, the changes of the (7)Be activity in the air and the total (wet and dry) deposition samples, as well as their correlation with meteorological parameters (temperature, pressure, cloudiness, sunshine duration, precipitation and humidity) that affect (7)Be concentration in the atmosphere, were mathematically described using the Fourier analysis. Fourier analysis confirmed the expected; the frequency with the largest intensity in the harmonic spectra of the (7)Be activity corresponds to a period of 1 year, the same as the largest intensity frequency in Fourier series of meteorological parameters. To analyze the quality of the results produced by the Fourier analysis, we compared the measured values of the parameters with the values calculated according to the Fourier series. Absolute deviations between measured and predicted mean monthly values are in range from 0.02 mBq/m(3) to 0.7 mBq/m(3) for (7)Be activity in air, and 0.01 Bq/m(2) and 0.6 Bq/m(2) for (7)Be activity in deposition samples. Relatively good agreement of measured and predicted results offers the possibility of prediction of the (7)Be activity. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Investigation of cosmogenic radionuclide carriers in the atmosphere

    International Nuclear Information System (INIS)

    Lujaniene, G.

    2000-01-01

    Speciation of 7 Be, 32 P, 33 P, 35 S and stable S carriers and their changes in the atmosphere were investigated. It has been determined that aerosol-carriers of 7 Be, 32 P and 33 P radionuclides can have different properties, and after several days their transformation was observed. The amount of water-soluble carriers in aerosol samples differed widely (from 11 to 95 %). The dependence of radionuclide carrier solubility on pH was obtained for 7 Be, 32 P and 33 P. It has been found that 7 Be carriers can be soluble compounds such as mixed chlorides, sulphates and nitrates as well as insoluble carbonates and insoluble hydrous Fe(III) oxides. High percentage of 32 P and 33 P was found in exchangeable fraction. The 35 S carriers were found to be more soluble than those of 7 Be, 32 P and 33 P and exhibited a lower or the same solubility as stable sulphur. (author)

  2. Cosmogenic 45Sc in Gibeon iron meteorite by radioanalytical neutron activation analysis

    International Nuclear Information System (INIS)

    Oura, Y.; Honda, M.; Ebihara, M.; Bajo, K.; Nagao, K.

    2011-01-01

    Cosmogenic nuclides in many fragments of Gibeon iron meteorite have been studied by Honda and coworkers. They observed that their concentrations varied by 5 orders and found that Gibeon gives two different exposure ages using pair of stable noble gas isotopes and radinuclide. To assess one possible cause for the difference, namely loss of partial noble gases due to atmospheric heating of the incoming meteoroid, concentrations of non-volatile and stable cosmogenic 45 Sc of Gibeon were determined by radiochemical neutron activation analysis (RNAA). For RNAA, a radiochemical procedure using extraction chromatography was developed to separate Sc from an iron meteorite. Concentrations of 45 Sc in 7 fragments ranged from 0.0064 to 0.11 ppb and correlated with cosmogenic 4 He concentrations. This correlation suggests that noble gases in Gibeon were not lost during the fall to the earth. (orig.)

  3. Cosmogenic activation of germanium used for tonne-scale rare event search experiments

    Science.gov (United States)

    Wei, W.-Z.; Mei, D.-M.; Zhang, C.

    2017-11-01

    We report a comprehensive study of cosmogenic activation of germanium used for tonne-scale rare event search experiments. The germanium exposure to cosmic rays on the Earth's surface are simulated with and without a shielding container using Geant4 for a given cosmic muon, neutron, and proton energy spectrum. The production rates of various radioactive isotopes are obtained for different sources separately. We find that fast neutron induced interactions dominate the production rate of cosmogenic activation. Geant4-based simulation results are compared with the calculation of ACTIVIA and the available experimental data. A reasonable agreement between Geant4 simulations and several experimental data sets is presented. We predict that cosmogenic activation of germanium can set limits to the sensitivity of the next generation of tonne-scale experiments.

  4. On scaling cosmogenic nuclide production rates for altitude and latitude using cosmic-ray measurements

    Science.gov (United States)

    Desilets, Darin; Zreda, Marek

    2001-11-01

    The wide use of cosmogenic nuclides for dating terrestrial landforms has prompted a renewed interest in characterizing the spatial distribution of terrestrial cosmic rays. Cosmic-ray measurements from neutron monitors, nuclear emulsions and cloud chambers have played an important role in developing new models for scaling cosmic-ray neutron intensities and, indirectly, cosmogenic production rates. Unfortunately, current scaling models overlook or misinterpret many of these data. In this paper, we describe factors that must be considered when using neutron measurements to determine scaling formulations for production rates of cosmogenic nuclides. Over the past 50 years, the overwhelming majority of nucleon flux measurements have been taken with neutron monitors. However, in order to use these data for scaling spallation reactions, the following factors must be considered: (1) sensitivity of instruments to muons and to background, (2) instrumental biases in energy sensitivity, (3) solar activity, and (4) the way of ordering cosmic-ray data in the geomagnetic field. Failure to account for these factors can result in discrepancies of as much as 7% in neutron attenuation lengths measured at the same location. This magnitude of deviation can result in an error on the order of 20% in cosmogenic production rates scaled from 4300 m to sea level. The shapes of latitude curves of nucleon flux also depend on these factors to a measurable extent, thereby causing additional uncertainties in cosmogenic production rates. The corrections proposed herein significantly improve our ability to transfer scaling formulations based on neutron measurements to scaling formulations applicable to spallation reactions, and, therefore, constitute an important advance in cosmogenic dating methodology.

  5. Evaluating steady-state soil thickness by coupling uranium series and 10Be cosmogenic radionuclides

    Science.gov (United States)

    Vanacker, Veerle; Schoonejans, Jerome; Opfergelt, Sophie; Granet, Matthieu; Christl, Marcus; Chabaux, Francois

    2017-04-01

    Within the Critical Zone, the development of the regolith mantle is controlled by the downwards propagation of the weathering front into the bedrock and denudation at the surface of the regolith by mass movements, water and wind erosion. When the removal of surface material is approximately balanced by the soil production, the soil system is assumed to be in steady-state. The steady state soil thickness (or so-called SSST) can be considered as a dynamic equilibrium of the system, where the thickness of the soil mantle stays relatively constant over time. In this study, we present and compare analytical data from two independent isotopic techniques: in-situ produced cosmogenic nuclides and U-series disequilibria to constrain soil development under semi-arid climatic conditions. The Spanish Betic Cordillera (Southeast Spain) was selected for this study, as it offers us a unique opportunity to analyze soil thickness steady-state conditions for thin soils of semiarid environments. Three soil profiles were sampled across the Betic Ranges, at the ridge crest of zero-order catchments with distinct topographic relief, hillslope gradient and 10Be-derived denudation rate. The magnitude of soil production rates determined based on U-series isotopes (238U, 234U, 230Th and 226Ra) is in the same order of magnitude as the 10Be-derived denudation rates, suggesting steady state soil thickness in two out of three sampling sites. The results suggest that coupling U-series isotopes with in-situ produced radionuclides can provide new insights in the rates of soil development; and also illustrate the potential frontiers in applying U-series disequilibria to track soil production in rapidly eroding landscapes characterized by thin weathering depths.

  6. Applications of in situ cosmogenic nuclides in the geologic site characterization of Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    Gosse, J.C.; Harrington, C.D.

    1995-01-01

    The gradual buildup of rare isotopes from interactions between cosmic rays and atoms in an exposed rock provides a new method of directly determining the exposure age of rock surfaces. The cosmogenic nuclide method can also provide constraints on erosion rates and the length of time surface exposure was interrupted by burial. Numerous successful applications of the technique have been imperative to the complete surface geologic characterization of Yucca Mountain, Nevada, a potential high level nuclear waste repository. In this short paper, we summarize the cosmogenic nuclide method and describe with examples some the utility of the technique in geologic site characterization. We report preliminary results from our ongoing work at Yucca Mountain

  7. Measurement of $^{7}$Be(n,$\\alpha$)$^{4}$He and $^{7}$Be(n,p)$^{7}$Li cross-sections for the Cosmological Lithium Problem

    CERN Multimedia

    We propose to measure in the second experimental area of n TOF the $^{7}$Be(n,$\\alpha$)$^{4}$He and $^{7}$Be(n,p)$^{7}$Li reaction in a wide energy range. Both reactions are of interest for the long- standing "Cosmological $^{7}$Li problem" in Big Bang Nucleosynthesis (BBN). The very high specific activity of $^{7}$Be, and the low cross section of the (n,$\\alpha$) reaction make this measurement extremely dicult. As afirst step, we request some beam time for detector tests at EAR2. For the $^{7}$Be(n,p) reaction, previously measured up to 13 keV, the diculty is mostly associated withthe availability of a high-purity $^{7}$Be sample. To this purpose we ask for three shifts of offline ISOLDE mass separation for the preparation of the sample to be used at n TOF. To this end, a prior endorsement by INTC of the scientific validity and feasibility of the proposed measurement is requested, to start activity on the sample production. The present proposal is part of a wider collaborative effort aimed at measuring neutr...

  8. THE {sup 7}Be ii RESONANCE LINES IN TWO CLASSICAL NOVAE V5668 SGR AND V2944 OPH

    Energy Technology Data Exchange (ETDEWEB)

    Tajitsu, Akito [Subaru Telescope, National Astronomical Observatory of Japan, 650 North A’ohoku Place, Hilo, HI 96720 (United States); Sadakane, Kozo [Astronomical Institute, Osaka Kyoiku University, Asahigaoka, Kashiwara, Osaka 582-8582 (Japan); Naito, Hiroyuki [Nayoro Observatory, 157-1 Nisshin, Nayoro, Hokkaido 096-0066 (Japan); Arai, Akira; Kawakita, Hideyo [Koyama Astronomical Observatory, Kyoto Sangyo University, Motoyama, Kamigamo, Kita-ku, Kyoto 603-8555 (Japan); Aoki, Wako, E-mail: tajitsu@naoj.org [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)

    2016-02-20

    We report spectroscopic observations of the resonance lines of singly ionized {sup 7}Be in the blueshifted absorption line systems found in the post-outburst spectra of two classical novae—V5668 Sgr (Nova Sagittarii 2015 No. 2) and V2944 Oph (Nova Ophiuchi 2015). The unstable isotope {sup 7}Be should have been created during the thermonuclear runaway (TNR) of these novae and decayed to form {sup 7}Li within a short period (a half-life of 53.22 days). These confirmations of {sup 7}Be are the second and the third ones following the first case found in V339 Del by Tajitsu et al. The blueshifted absorption line systems in both novae are clearly divided into two velocity components, both of which contain {sup 7}Be. This means that the absorbing gases in both velocity components consist of products of TNR. We estimated the amounts of {sup 7}Be produced during the outbursts of both novae and concluded that significant {sup 7}Li should have been created. These findings strongly suggest that the explosive production of {sup 7}Li via the reaction {sup 3}He(α,γ){sup 7}Be and its  subsequent decay to {sup 7}Li occurs frequently among classical novae and contributes to the process of Galactic Li enrichment.

  9. 7Be(n,α and 7Be(n,p cross-section measurement for the cosmological lithium problem at the n_TOF facility at CERN

    Directory of Open Access Journals (Sweden)

    Barbagallo M.

    2017-01-01

    Full Text Available The Cosmological Lithium Problem refers to the large discrepancy between the abundance of primordial 7Li predicted by the standard theory of Big Bang Nucleosynthesis and the value inferred from the so-called “Spite plateau” in halo stars. A possible explanation for this longstanding puzzle in Nuclear Astrophysics is related to the incorrect estimation of the destruction rate of 7Be, which is responsible for the production of 95% of primordial Lithium. While charged-particle induced reactions have mostly been ruled out, data on the 7Be(n,α and 7Be(n,p reactions are scarce or completely missing, so that a large uncertainty still affects the abundance of 7Li predicted by the standard theory of Big Bang Nucleosynthesis. Both reactions have been measured at the n_TOF facility at CERN, providing for the first time data in a wide neutron energy range.

  10. 7Be(n,α) and 7Be(n,p) cross-section measurement for the cosmological lithium problem at the n_TOF facility at CERN

    Science.gov (United States)

    Barbagallo, M.; Colonna, N.; Aberle, O.; Andrzejewski, J.; Audouin, L.; Bécares, V.; Bacak, M.; Balibrea, J.; Barros, S.; Bečvář, F.; Beinrucker, C.; Berthoumieux, E.; Billowes, J.; Bosnar, D.; Brugger, M.; Caamaño, M.; Calviño, F.; Calviani, M.; Cano-Ott, D.; Cardella, R.; Casanovas, A.; Castelluccio, D. M.; Cerutti, F.; Chen, Y. H.; Chiaveri, E.; Cortés, G.; Cortés-Giraldo, M. A.; Cosentino, L.; Damone, L. A.; Diakaki, M.; Domingo-Pardo, C.; Dressler, R.; Dupont, E.; Durán, I.; Fernández-Domínguez, B.; Ferrari, A.; Ferreira, P.; Finocchiaro, P.; Furman, V.; Göbel, K.; García, A. R.; Gawlik, A.; Glodariu, T.; Gonçalves, I. F.; González, E.; Goverdovski, A.; Griesmayer, E.; Guerrero, C.; Gunsing, F.; Harada, H.; Heftrich, T.; Heinitz, S.; Heyse, J.; Jenkins, D. G.; Jericha, E.; Käppeler, F.; Kadi, Y.; Katabuchi, T.; Kavrigin, P.; Ketlerov, V.; Khryachkov, V.; Kimura, A.; Kivel, N.; Kokkoris, M.; Krtička, M.; Leal-Cidoncha, E.; Lederer, C.; Leeb, H.; Lerendegui-Marco, J.; Meo, S. Lo; Lonsdale, S. J.; Losito, R.; Macina, D.; Marganiec, J.; Martínez, T.; Massimi, C.; Mastinu, P.; Mastromarco, M.; Matteucci, F.; Maugeri, E. A.; Mendoza, E.; Mengoni, A.; Milazzo, P. M.; Mingrone, F.; Mirea, M.; Montesano, S.; Musumarra, A.; Nolte, R.; Oprea, A.; Patronis, N.; Pavlik, A.; Perkowski, J.; Porras, J. I.; Praena, J.; Quesada, J. M.; Rajeev, K.; Rauscher, T.; Reifarth, R.; Riego-Perez, A.; Rout, P. C.; Rubbia, C.; Ryan, J. A.; Sabaté-Gilarte, M.; Saxena, A.; Schillebeeckx, P.; Schmidt, S.; Schumann, D.; Sedyshev, P.; Smith, A. G.; Stamatopoulos, A.; Tagliente, G.; Tain, J. L.; Tarifeño-Saldivia, A.; Tassan-Got, L.; Tsinganis, A.; Valenta, S.; Vannini, G.; Variale, V.; Vaz, P.; Ventura, A.; Vlachoudis, V.; Vlastou, R.; Wallner, A.; Warren, S.; Weigand, M.; Weiss, C.; Wolf, C.; Woods, P. J.; Wright, T.; Žugec, P.

    2017-09-01

    The Cosmological Lithium Problem refers to the large discrepancy between the abundance of primordial 7Li predicted by the standard theory of Big Bang Nucleosynthesis and the value inferred from the so-called "Spite plateau" in halo stars. A possible explanation for this longstanding puzzle in Nuclear Astrophysics is related to the incorrect estimation of the destruction rate of 7Be, which is responsible for the production of 95% of primordial Lithium. While charged-particle induced reactions have mostly been ruled out, data on the 7Be(n,α) and 7Be(n,p) reactions are scarce or completely missing, so that a large uncertainty still affects the abundance of 7Li predicted by the standard theory of Big Bang Nucleosynthesis. Both reactions have been measured at the n_TOF facility at CERN, providing for the first time data in a wide neutron energy range.

  11. Extraction of in situ cosmogenic 14C from olivine

    Science.gov (United States)

    Pigati, J.S.; Lifton, N.A.; Timothy, Jull A.J.; Quade, Jay

    2010-01-01

    Chemical pretreatment and extraction techniques have been developed previously to extract in situ cosmogenic radiocarbon (in situ 14C) from quartz and carbonate. These minerals can be found in most environments on Earth, but are usually absent from mafic terrains. To fill this gap, we conducted numerous experiments aimed at extracting in situ 14C from olivine ((Fe,Mg)2SiO4). We were able to extract a stable and reproducible in situ 14C component from olivine using stepped heating and a lithium metaborate (LiBO2) flux, following treatment with dilute HNO3 over a variety of experimental conditions. However, measured concentrations for samples from the Tabernacle Hill basalt flow (17.3 ?? 0.3 ka4) in central Utah and the McCarty's basalt flow (3.0 ?? 0.2 ka) in western New Mexico were significantly lower than expected based on exposure of olivine in our samples to cosmic rays at each site. The source of the discrepancy is not clear. We speculate that in situ 14C atoms may not have been released from Mg-rich crystal lattices (the olivine composition at both sites was ~Fo65Fa35). Alternatively, a portion of the 14C atoms released from the olivine grains may have become trapped in synthetic spinel-like minerals that were created in the olivine-flux mixture during the extraction process, or were simply retained in the mixture itself. Regardless, the magnitude of the discrepancy appears to be inversely proportional to the Fe/(Fe+Mg) ratio of the olivine separates. If we apply a simple correction factor based on the chemical composition of the separates, then corrected in situ 14C concentrations are similar to theoretical values at both sites. At this time, we do not know if this agreement is fortuitous or real. Future research should include measurement of in situ 14C concentrations in olivine from known-age basalt flows with different chemical compositions (i.e. more Fe-rich) to determine if this correction is robust for all olivine-bearing rocks. ?? 2010 by the Arizona

  12. Unravelling the Mysteries of Slip Histories, Validating Cosmogenic 36Cl Derived Slip Rates on Normal Faults

    Science.gov (United States)

    Goodall, H.; Gregory, L. C.; Wedmore, L.; Roberts, G.; Shanks, R. P.; McCaffrey, K. J. W.; Amey, R.; Hooper, A. J.

    2017-12-01

    The cosmogenic isotope chlorine-36 (36Cl) is increasingly used as a tool to investigate normal fault slip rates over the last 10-20 thousand years. These slip histories are being used to address complex questions, including investigating slip clustering and understanding local and large scale fault interaction. Measurements are time consuming and expensive, and as a result there has been little work done validating these 36Cl derived slip histories. This study aims to investigate if the results are repeatable and therefore reliable estimates of how normal faults have been moving in the past. Our approach is to test if slip histories derived from 36Cl are the same when measured at different points along the same fault. As normal fault planes are progressively exhumed from the surface they accumulate 36Cl. Modelling these 36Cl concentrations allows estimation of a slip history. In a previous study, samples were collected from four sites on the Magnola fault in the Italian Apennines. Remodelling of the 36Cl data using a Bayesian approach shows that the sites produced disparate slip histories, which we interpret as being due to variable site geomorphology. In this study, multiple sites have been sampled along the Campo Felice fault in the central Italian Apennines. Initial results show strong agreement between the sites we have processed so far and a previous study. This indicates that if sample sites are selected taking the geomorphology into account, then 36Cl derived slip histories will be highly similar when sampled at any point along the fault. Therefore our study suggests that 36Cl derived slip histories are a consistent record of fault activity in the past.

  13. Study of the concentration of {sup 7} Be in samples of rain water; Estudio de la concentracion de {sup 7} Be en muestras de agua de lluvia

    Energy Technology Data Exchange (ETDEWEB)

    Quintero P, E.; Rojas M, V.P. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)

    2004-07-01

    This work shows the methodology carried out for the determination of {sup 7} Be in samples of rain water and the obtained results of the concentration of having said radionuclide in this sampled matrix during the last five years in the Nuclear Center of Mexico. (Author)

  14. "7Be(n,α) "7Be(n,p) cross-section measurement for the Cosmological Lithium Problem at the n_TOF facility at CERN

    International Nuclear Information System (INIS)

    Barbagallo, M.

    2016-01-01

    The "7Be(n,α) reaction cross-section has been measured for the first time in a wide neutron energy range, in order to investigate its role in the destruction of "7Be during Big Bang Nucleosynthesis, as a possible solution to the Cosmological Lithium problem (CLiP). The measurement has been performed at the new vertical beam line of the neutron Time-of-Flight facility (n TOF) at CERN, taking advantage of the extremely high instantaneous neutron flux which allows to obtain the useful signal-to-background ratio particularly suited for challenging measurements on short-lived radioisotopes, such as "7Be (t_1_/_2 ≃ 53.2days). The two alfa particles emitted back-to-back in the reaction have been detected by mean of sandwiches of silicon detectors and exploiting the coincidence technique. In order to complete the n TOF program on CLiP, the "7Be(n,p) cross-section will be measured during the next n TOF experimental campaign, using an high-purity sample and a silicon telescope device.

  15. Constraining the 7Be(p,γ)8B S-factor with the new precise 7Be solar neutrino flux from Borexino

    Science.gov (United States)

    Takács, M. P.; Bemmerer, D.; Junghans, A. R.; Zuber, K.

    2018-02-01

    Among the solar fusion reactions, the rate of the 7Be(p , γ)8B reaction is one of the most difficult to determine rates. In a number of previous experiments, its astrophysical S-factor has been measured at E = 0.1- 2.5 MeV centre-of-mass energy. However, no experimental data is available below 0.1 MeV. Thus, an extrapolation to solar energies is necessary, resulting in significant uncertainty for the extrapolated S-factor. On the other hand, the measured solar neutrino fluxes are now very precise. Therefore, the problem of the S-factor determination is turned around here: Using the measured 7Be and 8B neutrino fluxes and the Standard Solar Model, the 7Be(p , γ)8B astrophysical S-factor is determined at the solar Gamow peak. In addition, the 3He(α , γ)7Be S-factor is redetermined with a similar method.

  16. A 30000 yr record of erosion rates from cosmogenic 10Be in middle European river terraces

    NARCIS (Netherlands)

    Schaller, M.; Blanckenburg, von F.; Veldkamp, A.; Tebbens, L.A.; Hovius, N.; Kubik, P.W.

    2002-01-01

    Cosmogenic 10Be in river-borne quartz sand records a time-integrated erosion rate representative of an entire drainage basin. When sequestered in a terrace of known age, paleo-erosion rates may be recovered from the nuclide content of the terrace material. Paleo-erosion rates between 30 and 80

  17. Balance of the tropospheric ozone and its relation to stratospheric intrusions indicated by cosmogenic radionuclides. Technical progress report, 1 November 1977--30 June 1978

    International Nuclear Information System (INIS)

    Reiter, R.; Kanter, H.J.; Sladkovic, R.; Jaeger, H.; Mueller, H.

    1978-01-01

    The study of the balance of the tropospheric ozone as a function of atmospheric pollutants and tropospheric transport has been started. Continuous recordings are available of ozone concentration at three levels (3000 m, 1800 m, and 700 m a.s.l.) and of the concentration of the cosmogenic radionuclides 7 Be, 32 P, 33 P, and the CO 2 -concentration. Ozone concentrations >70 ppB have been observed after stratospheric intrusions as well as in consequence of photochemical reactions in the boundary layer. An observation sequence, covering now a period of 20 months, is presented of the stratospheric aerosol layer by means of lidar monitoring. Possible errors in the measuring technique are discussed. A filter photospectrometer for the measurement of the atmospheric total ozone is described, its suitability is checked by a direct intercomparison with a Dobson spectrometer

  18. Analysis of 7Be behaviour in the air by using a multilayer perceptron neural network

    International Nuclear Information System (INIS)

    Samolov, A.; Dragović, S.; Daković, M.; Bačić, G.

    2014-01-01

    A multilayer perceptron artificial neural network (ANN) model for the prediction of the 7 Be behaviour in the air as the function of meteorological parameters was developed. The model was optimized and tested using 7 Be activity concentrations obtained by standard gamma-ray spectrometric analysis of air samples collected in Belgrade (Serbia) during 2009–2011 and meteorological data for the same period. Good correlation (r = 0.91) between experimental values of 7 Be activity concentrations and those predicted by ANN was obtained. The good performance of the model in prediction of 7 Be activity concentrations could provide basis for construction of models which would forecast behaviour of other airborne radionuclides. - Highlights: • Neural network analysis was used to predict airborne 7 Be activity using meteorological parameters as inputs. • Strong correlation between calculated and measured activities was found. • Obtained results can help in construction of a general model of 7 Be activity variation in air

  19. Determination of the mean aerosol residence times in the atmosphere and additional 210Po input on the base of simultaneous determination of 7Be, 22Na, 210Pb, 210Bi and 210Po in urban air

    International Nuclear Information System (INIS)

    Magdalena Dlugosz-Lisiecka; Henryk Bem

    2012-01-01

    The significant differences in the activities of 210 Pb, 210 Bi, 210 Po and cosmogenic 7 Be and 22 Na radionuclides in the urban aerosol samples collected in the summers 2010 and 2011 in the Lodz city of Poland were observed. Simultaneous measurement of these radionuclides, after a simple modification of the one compartment model, allows us to calculate both: the corrected aerosol residence times in the troposphere (1 / 25 days) and in the lower stratosphere (103 / 205 days). The relative input of the additional sources (beside of the 222 Rn decay in the air) to the total activity concentrations of 210 Pb, 210 Bi and 210 Po radionuclides in the urban air, plays a substantial role (up to 97% of the total activity) only in the case of 210 Po. (author)

  20. Quantifying the Fluxes of Atmospherically Derived Trace Elements in the Arctic Ocean/Ice System using 7Be

    Science.gov (United States)

    Landing, W. M.; Kadko, D. C.; Shelley, R.; Galfond, B.

    2016-02-01

    Aerosol deposition is an important pathway for delivering biologically-essential and anthropogenically-derived trace elements to the Arctic Ocean. Limited field study in the harsh Arctic environment has forced a reliance on poorly constrained models for the atmospheric deposition of trace elements. Here we use the cosmic ray produced radioisotope 7Be to link aerosol concentrations to flux to the Arctic water/ice system. Seawater, ice, snow, melt pond, and aerosol samples were collected during late summer 2011 as part of the RV Polarstern ARK-XXVI/3 campaign. The average 7Be aerosol loading was 0.018 dpm m-3 and we determined an average 7Be flux of 125 dpm m-2 d-1, consistent with results from previous studies in the region. None of the lithogenic aerosol elements showed any significant enrichment above crustal composition, while the pollution-type elements showed varying degrees of enrichment relative to crustal values. In addition to our own measurements, we use two years of continuous aerosol 7Be and trace element data from the Alert (Canada) monitoring site to generate seasonal and annual estimates for the fluxes of 7Be and trace elements to the Arctic water/ice system. Fluxes of 7Be are 30% higher in Winter (Nov-May) than in Summer (Jun-Oct) due to the strong seasonality in aerosol 7Be concentrations. Fluxes of lithogenic elements (Al, Mn, Fe) are 2-3 times higher in Summer, possibly due to local dust sources on Ellesmere Island. Fluxes of V and Pb are strongly correlated and are 2-3 times higher in Winter, while fluxes of Ni, Cu, and Zn are relatively uniform for both seasons.

  1. Seasonality of 7Be concentrations in Europe and influence of tropopause height

    Directory of Open Access Journals (Sweden)

    Miguel Angel Hernández-Ceballos

    2016-05-01

    Full Text Available This study aims at analysing the latitudinal variability of both the yearly and seasonal pattern of 7Be surface activity concentrations, at addressing the impact of tropopause height (TPH on 7Be distribution and at evaluating the time lag between TPH and 7Be at European level. With this aim, weekly 7Be and daily TPH data at 17 sampling stations during 10 yr (2001–2010 are analysed. 7Be shows a clear increasing tendency in the period and generally tends to increase with decreasing latitude. The seasonal pattern generally shows maxima during the warm period and minima during the cold one. The seasonal variogram analysis points out a good spatial correlation for TPH data while a weaker one is observed for 7Be, having TPH a larger influence on 7Be during summer. The influence of TPH on 7Be exhibits a large spatial variability, with a clear gap between south and north in the area of the polar front jet. The results identify the presence of two main groups, in particular separating between stations located in northern Europe (50 °N and higher and stations in southern Europe (south of 50 °N. A similar behaviour for stations located in the same geographical area is also observed when looking at the day of maximum impact of TPH on 7Be concentrations. The results suggest that 7Be concentrations respond in different time ranges to changes in the TPH, observing seasonal differences in each group. These results represent the first European approach to the understanding of the TPH impact on 7Be concentrations at surface levels.

  2. Monitoring of 7Be in surface air of varying PM10 concentrations

    International Nuclear Information System (INIS)

    Chao, J.H.; Liu, C.C.; Cho, I.C.; Niu, H.

    2014-01-01

    In this study, beryllium-7 ( 7 Be) concentrations of surface air were monitored throughout a span of 23 years (1992–2012) in the Taiwanese cities Yilan, Taipei, Taichung, and Kaohsiung. During this period, particulate matter (PM) concentrations, in terms of PM 10 , were collected monthly from the nearest air-quality pollutant monitoring stations and compared against 7 Be concentrations. Seasonal monsoons influenced 7 Be concentrations in all cities, resulting in high winter and low summer concentrations. In addition, the meteorological conditions caused seasonal PM 10 variations, yielding distinct patterns among the cities. There was no correlation between 7 Be and PM 10 in the case cities. The average annual 7 Be concentrations varied little among the cities, ranging from 2.9 to 3.5 mBq/m 3 , while the PM 10 concentrations varied significantly from 38 μg/m 3 in Yilan to 92 μg/m 3 in Kaohsiung depending on the degree of air pollution and meteorological conditions. The correlation between the 7 Be concentration and gross-beta activities (A β ) in air implied that the 7 Be was mainly attached to crustal PM and its concentration varied little among the cities, regardless of the increase in anthropogenic PM in air-polluted areas. - Highlights: • Both 7 Be and PM 10 concentrations were monitored in four Taiwanese cities from 1992 to 2012. • Seasonal variations of 7 Be and PM 10 were explained based on on meteorological and pollution conditions. • The annual concentrations of 7 Be varied little among the four cities even in high PM environment. • 7 Be is believed to mainly attach to natural PM in the cities that exhibited varying PM 10 concentrations

  3. Cosmogenic nuclide age estimate for Laurentide Ice Sheet recession from the terminal moraine, New Jersey, USA, and constraints on latest Pleistocene ice sheet history

    Science.gov (United States)

    Corbett, Lee B.; Bierman, Paul R.; Stone, Byron D.; Caffee, Marc W.; Larsen, Patrick L.

    2017-01-01

    The time at which the Laurentide Ice Sheet reached its maximum extent and subsequently retreated from its terminal moraine in New Jersey has been constrained by bracketing radiocarbon ages on preglacial and postglacial sediments. Here, we present measurements of in situ produced 10Be and 26Al in 16 quartz-bearing samples collected from bedrock outcrops and glacial erratics just north of the terminal moraine in north-central New Jersey; as such, our ages represent a minimum limit on the timing of ice recession from the moraine. The data set includes field and laboratory replicates, as well as replication of the entire data set five years after initial measurement. We find that recession of the Laurentide Ice Sheet from the terminal moraine in New Jersey began before 25.2±2.1 ka (10Be, n=16, average, 1 standard deviation). This cosmogenic nuclide exposure age is consistent with existing limiting radiocarbon ages in the study area and cosmogenic nuclide exposure ages from the terminal moraine on Martha’s Vineyard ~300 km to the northeast. The age we propose for Laurentide Ice Sheet retreat from the New Jersey terminal position is broadly consistent with regional and global climate records of the last glacial maximum termination and records of fluvial incision.

  4. Transfer of 7Be, 210Pb and 210Po in a forest canopy of Japanese cedar

    International Nuclear Information System (INIS)

    Osaki, S.; Tagawa, Y.; Sugihara, S.; Maeda, Y.; Inokura, Y.

    2003-01-01

    The concentrations of 7 Be, 210 Pb and 210 Po of ca. 60 parts of a whole tree of Japanese cedar and of underlying litter and soil samples were determined for studying their transfer in a forest canopy. The results suggest that the mean residence times of 7 Be and 210 Pb in the forest canopy were ca. 20 and 900 days, respectively, and the dry deposition rate of 7 Be on the forest canopy was about a half of the total deposition rate. (author)

  5. Annual variation of 7Be soil inventory in a semiarid region of central Argentina

    International Nuclear Information System (INIS)

    Lohaiza, F.; Velasco, H.; Juri Ayub, J.; Rizzotto, M.; Di Gregorio, D.E.; Huck, H.; Valladares, D.L.

    2014-01-01

    Reliable information on environmental radionuclides atmospheric entrance, and their distribution along the soil profile, is a necessary condition for using these soil and sediment tracers to investigate key environmental processes. To address this need, 7 Be content in rainwater and the wet deposition in a semiarid region at San Luis Province, Argentina, were studied. Following these researches, in the same region, we have assessed the 7 Be content along a soil profile, during 2.5 years from September 2009 to January 2012. As expected, the specific activity values in soil samples in the wet period (November–April) were higher than in the dry period (May–October). During the investigated period (2009 – beginning 2012) and for all sampled points, the maximum value of the 7 Be specific activity (Bq kg −1 ) was measured at the surface level. A typical decreasing exponential function of 7 Be areal activity (Bq m −2 ) with soil mass depth (kg m −2 ) was found and the key distribution parameters were determined for each month. The minimum value of areal activity was 51 Bq m −2 in August, and the maximum was 438 Bq m −2 in February. The relaxation mass depth ranges from 2.9 kg m −2 in March to 1.3 kg m −2 in August. 7 Be wet deposition can explain in a very significant proportion the 7 Be inventory in soil. During the period of winds in the region (September and October), the 7 Be content in soil was greater than the expected contribution from wet deposition, situation that is compatible with a higher relative contribution of dry deposition at this period of the year. - Highlights: • The 7 Be content along the soil profile in a semiarid region of Argentina was assessed. • The 7 Be areal activity on soil shows an exponentially decreasing distribution with mass depth. • The relaxation mass depth ranging from 2.9 kg m −2 to 1.3 kg m −2 in wet and dry period respectively. • A simple model is used to determine the 7 Be content in soil from the 7

  6. Measurement of the $^{7}$Be$(p,\\gamma)^{8}$B Cross-Section with an Implanted Target

    CERN Document Server

    2002-01-01

    % IS366\\\\ \\\\ The $^7$Be(p,$\\gamma)^8$B capture reaction is of major importance to the physics of the sun and the issues of the ``solar neutrino puzzle'' and neutrino masses. We report here on a new determination of the absolute cross section of this reaction, using a novel method which overcomes some of the major experimental uncertainties of previous measurements. We utilize an implanted $^7$Be target and a uniformly scanned particle beam larger than the target spot, eliminating issues of target homogeneity and backscattering loss of $^8$B reaction products. The target was produced using a beam of 1.8 10$^{10}$/s $^7$Be nuclei extracted at ISOLDE(CERN) from a graphite target bombarded by 1 GeV protons in a two-step resonant laser ionization source. The $^7$Be nuclei were directly implanted into a copper substrate to obtain a target of 2 mm diameter with a total of 3.10$^{15}$ atoms. The measurement of the $^8$B production cross section was carried out at the Van de Graaff laboratory of the Weizmann Institute...

  7. Direct Measurement of the 7Be Solar Neutrino Flux with 192 Days of Borexino Data

    International Nuclear Information System (INIS)

    Arpesella, C.; Di Pietro, G.; Monzani, M. E.; Back, H. O.; Hardy, S.; Joyce, M.; Manecki, S.; Raghavan, R. S.; Rountree, D.; Vogelaar, R. B.; Balata, M.; Di Credico, A.; Gazzana, S.; Korga, G.; Laubenstein, M.; Orsini, M.; Papp, L.; Razeto, A.; Tartaglia, R.; Bellini, G.

    2008-01-01

    We report the direct measurement of the 7 Be solar neutrino signal rate performed with the Borexino detector at the Laboratori Nazionali del Gran Sasso. The interaction rate of the 0.862 MeV 7 Be neutrinos is 49±3 stat ±4 syst counts/(day·100 ton). The hypothesis of no oscillation for 7 Be solar neutrinos is inconsistent with our measurement at the 4σ C.L. Our result is the first direct measurement of the survival probability for solar ν e in the transition region between matter-enhanced and vacuum-driven oscillations. The measurement improves the experimental determination of the flux of 7 Be, pp, and CNO solar ν e , and the limit on the effective neutrino magnetic moment using solar neutrinos

  8. The solar forcing on the 7Be-air concentration variability at ground level

    International Nuclear Information System (INIS)

    Talpos, Simona

    2004-01-01

    This paper analyses the correlation between the temporal and spatial variability of 7 Be-air concentration at ground level and the amount of precipitation. There were used the measured data from 26 stations distributed on North America, South America, Australia and Antarctica. The variability study was made using EOF and principal components analysis. The presented results show that the variability of 7 Be air concentration at ground level is simultaneously influenced by the solar cycle and some atmospheric processes like precipitation, turbulent transport, advection, etc. The solar forcing on the 7 Be variability at ground level was outlined for time-scales longer than 1 year and can be considered a global phenomenon. The atmospheric processes influence the 7 Be variability for scale shorter than one year and can be considered a local phenomenon. (author)

  9. Determination of S17 from the 7Be(d,n)8B reaction

    International Nuclear Information System (INIS)

    Ogata, Kazuyuki; Kamimura, Masayasu; Yahiro, Masanobu; Iseri, Yasunori

    2003-01-01

    The astrophysical factor S 17 for 7 Be(p,γ) 8 B reaction is reliably extracted from the transfer reaction 7 Be(d,n) 8 B at E=7.5 MeV with the asymptotic normalization coefficient method. The transfer reaction is accurately analyzed with CDCC based on a three-body model. This analysis is free from uncertainties of the optical potentials having been crucial in the previous DWBA analyses

  10. Importance of the tensor interaction in the (/sup 7/Li, /sup 7/Be) reaction

    Energy Technology Data Exchange (ETDEWEB)

    Dodd, A.C.; Clarke, N.M.; Coopersmith, J.; Griffiths, R.J.; Pearce, K.I.; Stanley, B.; Cook, J.

    1985-09-01

    Data for the /sup 28/Si(/sup 7/Li, /sup 7/Be)/sup 28/Al reaction at 72 MeV and for the /sup 26/Mg(/sup 7/Li, /sup 7/Be)/sup 26/Na reaction at 88 MeV are presented together with one-step DWBA calculations using microscopic form factors. The tensor interaction is shown to be important to explain the structureless nature of the angular distributions.

  11. The importance of the tensor interaction in the (7Li, 7Be) reaction

    International Nuclear Information System (INIS)

    Dodd, A.C.; Clarke, N.M.; Coopersmith, J.; Griffiths, R.J.; Pearce, K.I.; Stanley, B.; Cook, J.

    1985-01-01

    Data for the 28 Si( 7 Li, 7 Be) 28 Al reaction at 72 MeV and for the 26 Mg( 7 Li, 7 Be) 26 Na reaction at 88 MeV are presented together with one-step DWBA calculations using microscopic form factors. The tensor interaction is shown to be important to explain the structureless nature of the angular distributions. (author)

  12. Determining timing of Alaska Range exhumation and glaciation through cosmogenic nuclide burial dating.

    Science.gov (United States)

    Sortor, R. N.; Goehring, B. M.; Bemis, S. P.; Ruleman, C.; Nichols, K. A.; Ward, D. J.; Frothingham, M.

    2017-12-01

    The Alaska Range is a transpressional orogen with modern exhumation initiating 6 Ma. The stratigraphic record of unroofing and uplift of the foreland basin is largely preserved along the northern flank of the Alaska Range in the Pliocene-Pleistocene aged Nenana Gravel, an extensive alluvial fan and braidplain deposit. Chronometric control on the Nenana Gravel is largely lacking, with the limited available age control based on a single Ar-Ar tephra date in an underlying unit and via stratigraphic inferences for the upper portions. Higher-resolution dating of the Nenana Gravel unit is imperative in order to quantify deposition rates and the timing of uplift and deformation of the foreland basin. Furthermore, a glacial unit has been found to lie unconformably on top of the unit at Suntrana Creek and may represent the initiation of glacial advances in the Alaska Range. We present a suite of 26Al/10Be cosmogenic nuclide burial ages collected from the lower, middle, and upper sections of the Nenana Gravel at Suntrana Creek, as well as the overlying glacial unit. Three samples from the lower Nenana Gravel yield an isochron burial age of 4.42+0.67/-0.13 Ma, which represents initiation of Nenana Gravel deposition and may equate to early unroofing of the Alaska Range. Two samples collected from the middle of the Nenana Gravel unit produced an average simple burial age of 2.25+/-0.45 Ma, with a single sample stratigraphically above dating to 0.99 +/-1.60. Two samples from the upper-most portion of the Nenana Gravel yielded an average simple burial age of 1.27+/-0.22 Ma, and one sample from the glacial unit overlying the Nenana Gravel was dated to 0.97+/-0.06 Ma, representing one of the earliest glacial advances in the region. In addition, the age of the glacial unit provides a minimum age for inception of foreland basin uplift and abandonment of the Nenana Gravel in this region.

  13. Active basement uplift as seen with cosmogenic lenses: the Sierra Pie de Palo case (Western Argentina)

    Science.gov (United States)

    Siame, L. L.; Sébrier, M.; Costa, C. H.; Ahumada, E. A.; Bellier, O.

    2013-12-01

    The Andean foreland of western Argentina (28°S-33°S) corresponds to retroarc deformations associated with the ongoing flat subduction of the Nazca plate beneath the South American lithosphere, and associated with high levels of seismic activity and crustal active faulting. To improve earthquake source identification and characterization in the San Juan region, data from seismology, structural geology and quantitative geomorphology can be integrated and combined to provide a seismotectonic model. In this model, the Andean back-arc of western Argentina has to be regarded as an obliquely converging foreland where Plio-Quaternary deformations are partitioned between strike-slip and thrust motions that are localized on the E-verging, thin-skinned Argentine Precordillera, and the W-verging thick-skinned Sierras Pampeanas, respectively. In this domain, the Sierra Pie de Palo is a key structure playing a major role in the partitioning of the Plio-Quaternary deformations. Located in the westernmost Sierras Pampeanas, the Sierra Pie de Palo forms a NNE striking, 80 km-long and 35-40 km-wide, ellipsoid range that reaches elevation as high as 3162 m. This mountain range is an actively growing basement fold associated with a high level of seismic activity (e.g., the November 23, 1977, Caucete, Mw 7.4 earthquake). To evaluate the degree of tectonic activity around the Sierra Pie de Palo, we combined a detailed morphometric analysis of the topography together with in situ-produced cosmogenic 10Be concentrations measured in (1) bedrock outcrops corresponding to the exhumed erosional regional surface, (2) surface boulders abandoned on alluvial fans deformed by active faults, and (3) in fluvial sediments sampled at the outlets of selected watersheds that drains out from the Sierra Pie de Palo. All together, our results allows: (1) assessing quantitative constraints on the rate of tectonic and denudation processes that are responsible for the active growth and erosion of the Sierra

  14. Model for GCR-particle fluxes in stony meteorites and production rates of cosmogenic nuclides

    International Nuclear Information System (INIS)

    Reedy, R.C.

    1984-01-01

    A model is presented for the differential fluxes of galactic-cosmic-ray (GCR) particles with energies above 1 MeV inside any spherical stony meteorite as a function of the meteorite's radius and the sample's depth. This model is based on the Reedy-Arnold equations for the energy-dependent fluxes of GCR particles in the moon and is an extension of flux parameters that were derived for several meteorites of various sizes. This flux is used to calculate the production rates of many cosmogenic nuclides as a function of radius and depth. The peak production rates for most nuclides made by the reactions of energetic GCR particles occur near the centers of meteorites with radii of 40 to 70 g cm -2 . Although the model has some limitations, it reproduces well the basic trends for the depth-dependent production of cosmogenic nuclides in stony meteorites of various radii. These production profiles agree fairly well with measurements of cosmogenic nuclides in meteorites. Some of these production profiles are different than those calculated by others. The chemical dependence of the production rates for several nuclides varies with size and depth. 25 references, 8 figures

  15. Study of the {sup 10}B(p,α){sup 7}Be reaction through the indirect Trojan Horse method

    Energy Technology Data Exchange (ETDEWEB)

    Puglia, S. M. R., E-mail: puglia@lns.infn.it [INFN Laboratori Nazionali del Sud and CSFNM-Centrosiciliano Fisica Nucleare e Struttura della Materia,Catania (Italy); Spitaleri, C.; Lamia, L.; Romano, S.; La Cognata, M.; Pizzone, R. G.; Rapisarda, G. G.; Sergi, M. L. [INFN Laboratori Nazionali del Sud and DMFCI- Università di Catania, Catania (Italy); Burjan, V.; Kroha, V.; Hons, Z.; Mrazek, J. [Institute for Nuclear Physics, Prague-Rez (Czech Republic); Carlin, N.; Del Santo, M. G.; Munhoz, M. G.; Souza, F.; Szanto de Toledo, A. [Universidade de São Paulo - DFN, São Paulo (Brazil); Chengbo, L.; Qungang, W.; Shu-Hua, Z. [China Institute of Atomic Energy, Beijing (China); and others

    2015-02-24

    Boron abundances in stellar atmospheres, as well as berillium and lithium ones, can give useful hints for non-standard transport processes discrimination in stars. They can also be relevant for understanding several astrophysical processes (e.g. primordial nucleosynthesis and spallation reactions in ISM). A comprehensive study of Li Be B abundances can therefore confirm or not the presence of non-standard mixing processes in stellar envelopes. For this reason nuclear processes producing or depleting boron isotope abundance need to be studied at astrophysical energies. The {sup 10}B(p,α){sup 7}Be reaction has been studied by means of the Trojan Horse Method. The Trojan Horse Method was thus applied to the {sup 10}B(d,α{sup 7}Be)n reaction, studied at 24 MeV. The obtained results will be discussed.

  16. Do cosmogenic nuclides (10Be, 14C , 21Ne, 26Al) track late Quaternary climate changes on the Altiplano?

    Science.gov (United States)

    Hippe, K.; Kober, F.; Zeilinger, G.; Ivy-Ochs, S.; Kubik, P.; Maden, C.; Wieler, R.

    2010-12-01

    The high Altiplano plateau is the most prominent element of the Central Andes, separating the Andean Cordilleras between 15° to 22° S. It represents a tectonically quiet, intramontane basin with arid to semi-arid climate, low relief and internal drainage. Throughout the late Quaternary regional climate on the Altiplano repeatedly changed between wet and dry conditions [1]. The influence of climate on the plateau evolution during the Pleistocene/Holocene is unclear, however, as data on erosion processes and rates on the Altiplano are sparse. Here, we present a multiple-nuclide study investigating surface denudation at the eastern Altiplano of Bolivia (16°-17° S) on millennial and longer timescales. The aim is a better understanding of the complex feedback between climate, tectonics and geomorphology on the topographic evolution of the Andes. Catchment-wide denudation (CWD) rates are provided for a 150 km NW-SE transect along the Altiplano edge based on the analyses of cosmogenic 10Be, 26Al, 21Ne and in-situ 14C in river-borne sediment. Single nuclide CWD rates obtained for 10Be, 26Al and 21Ne are similar for all three nuclides and on the order of 3-37 mm/ka. Thus, the calculated denudation rates provide an averaged denudation history dating back at least to the middle Pleistocene. Denudation rates correlate positively with the mean basin hillslope, which is mainly controlled by basin lithology. For most catchments both, the 26Al/10Be ratios and the 21Ne/10Be ratios indicate a complex erosion/exposure history with probably several periods of sediment storage and burial/shielding totalling ~0.5 - 1.2 Ma. Local geomorphology featuring low slopes and low relief, small terraces and local floodplains also suggests that sediment transport might have been periodically ineffective. Concentrations of in-situ produced short-lived 14C are significantly lower than expected from the concentrations of the long-lived and stable cosmogenic nuclides. This would indicate a 30

  17. Atmospheric deposition patterns of (210)Pb and (7)Be in Cienfuegos, Cuba.

    Science.gov (United States)

    Alonso-Hernández, Carlos M; Morera-Gómez, Yasser; Cartas-Águila, Héctor; Guillén-Arruebarrena, Aniel

    2014-12-01

    The radiometric composition of bulk deposition samples, collected monthly for one year, February 2010 until January 2011, at a site located in Cienfuegos (22° 03' N, 80° 29' W) (Cuba), are analysed in this paper. Measurement of (7)Be and (210)Pb activity concentrations were carried out in 12 bulk deposition samples. The atmospheric deposition fluxes of (7)Be and (210)Pb are in the range of 13.2-132 and 1.24-8.29 Bq m(-2), and their mean values are: 56.6 and 3.97 Bq m(-2), respectively. The time variations of the different radionuclide have been discussed in relation with meteorological factors and the mean values have been compared to those published in recent literature from other sites located at different latitudes. The annual average flux of (210)Pb and (7)Be were 47 and 700 Bq m(-2) y(-1), respectively. Observed seasonal variations of deposition data are explained in terms of different environmental features. The atmospheric deposition fluxes of (7)Be and (210)Pb were moderately well correlated with precipitation and well correlated with one another. The (210)Pb/(7)Be ratios in the monthly depositions samples varied in the range of 0.05-0.10 and showed a strong correlation with the number of rainy days. Copyright © 2014 Elsevier Ltd. All rights reserved.

  18. Atmospheric concentrations of 7Be and 210Pb in Granada, Spain

    International Nuclear Information System (INIS)

    Azahra, M.; Gonzalez-Gomez, C.; Instituto Andaluz de Ciencias de la Tierra, Granada; Lopez-Penalver, J.J.; Camacho-Garcia, M.A.; El Bardouni, T.; Boukhal, H.

    2004-01-01

    Aerosols samples in near-surface air of Granada (Spain) were collected on a weekly basis. The seasonal 210 Pb and 7 Be concentrations were determined during the five-year period, from October 1993 to September 1997. The elements, despite their different origin and their different distribution throughout the atmosphere, present the same seasonal variation. There was a tendency for a maximum during the summer season and a minimum during fall and/or winter. Concentration of 7 Be and 210 Pb and meteorological data have been used in order to determine the periods of the potential radioactive pollution. Deposition of 7 Be occurs primarily by precipitation except during the investigation periods where precipitation was scarce and irregular. (author)

  19. Reaction dynamics studies for the system 7Be + 208Pb at Coulomb barrier energies

    Directory of Open Access Journals (Sweden)

    Mazzocco M.

    2017-01-01

    Full Text Available The scattering process of the Radioactive Ion Beam 7Be from a 208Pb target was measured at three near-barrier energies. The quasi-elastic angular distributions were analyzed within the framework of the optical model to extract the reaction cross sections. The results are compared with those obtained for the reactions induced by the mirror projectile 7Li and by the lightest particle-stable lithium isotope 6Li on the same target. The angular distributions for the production of the two 7Be constituent clusters, namely 3He and 4He, were also measured. In agreement with what observed for the interaction of 7Be with lighter targets, the production of the heavier helium isotope resulted to be much more abundant than that of its lighter counterpart.

  20. Reaction dynamics studies for the system 7Be + 208Pb at Coulomb barrier energies

    Science.gov (United States)

    Mazzocco, M.; Boiano, A.; Boiano, C.; La Commara, M.; Manea, C.; Parascandolo, C.; Pierroutsakou, D.; Strano, E.; Torresi, D.; Acosta, L.; Di Meo, P.; Fernandez-Garcia, J. P.; Glodariu, T.; Grebosz, J.; Guglielmetti, A.; Marquinez-Duran, G.; Martel, I.; Nicoletto, M.; Pakou, A.; Sánchez-Benítez, A. M.; Sava, T.; Sgouros, O.; Signorini, C.; Soramel, F.; Soukeras, V.; Stroe, L.

    2017-11-01

    The scattering process of the Radioactive Ion Beam 7Be from a 208Pb target was measured at three near-barrier energies. The quasi-elastic angular distributions were analyzed within the framework of the optical model to extract the reaction cross sections. The results are compared with those obtained for the reactions induced by the mirror projectile 7Li and by the lightest particle-stable lithium isotope 6Li on the same target. The angular distributions for the production of the two 7Be constituent clusters, namely 3He and 4He, were also measured. In agreement with what observed for the interaction of 7Be with lighter targets, the production of the heavier helium isotope resulted to be much more abundant than that of its lighter counterpart.

  1. Spectroscopic information from (3He, 7Be) reaction on 12C and 24Mg

    International Nuclear Information System (INIS)

    Rahman, Md.A.; Sen Gupta, H.M.

    1986-01-01

    The reaction ( 3 He, 7 Be) on 12 C and 24 Mg has been analysed using four discrete potential families for 7 Be channel and one discrete potential family for 3 He channel to extract alpha spectroscopic factors. It is shown that the relative spectroscopic factors are reliable if they are calculated staying within one potential family (S( 24 Mg/ 12 C) approx. 0.12). But, changing the potential family between 12 C and 24 Mg, one obtains the extreme cases, such as S( 24 Mg/ 12 C) = 0.025 and 0.51, i.e. 1:20

  2. Terrestrial cosmogenic 3He: where are we 30 years after its discovery?

    Science.gov (United States)

    Blard, Pierre-Henri; Pik, Raphaël; Farley, Kenneth A.; Lavé, Jérôme; Marrocchi, Yves

    2016-04-01

    It is now 30 years since cosmogenic 3He has been detected for the first time in a terrestrial sample (Kurz, 1986). 3He is now a widely used geochemical tool in many fields of Earth sciences: volcanology, tectonics, paleoclimatology. 3He has the advantage to have a high "production rate" to "detection limit" ratio, allowing surfaces as young as hundred of years to be dated. Although its nuclear stability implies several limitations, it moreover represents a useful alternative to 10Be in mafic environments. This contribution is a review of the progresses that have been accomplished since this discovery, and discuss strategies to improve both the accuracy and the precision of this geochronometer. 1) Measurement of cosmogenic 3He Correction of magmatic 3He. To estimate the non-cosmogenic magmatic 3He, Kurz (1986) invented a two steps method involving crushing of phenocrysts (to analyze the isotopic ratio of the magmatic component), followed by a subsequent melting of the sample, to extract the remaining components, including the cosmogenic 3He: 3Hec = 3Hemelt -4Hemelt x (3He/4He)magmatic (1) Several studies suggested that the preliminary crushing may induce a loss of cosmogenic 3He (Hilton et al., 1993; Yokochi et al., 2005; Blard et al., 2006), implying an underestimate of the cosmogenic 3He measurement. However, subsequent work did not replicate these observations (Blard et al., 2008; Goerhing et al., 2010), suggesting an influence of the used apparatus. An isochron method (by directly melting several phenocrysts aliquots) is an alternative to avoid the preliminary crushing step (Blard and Pik, 2008). Atmospheric contamination. Protin et al. (in press) provides robust evidences for a large and irreversible contamination of atmospheric helium on silicate surfaces. This unexpected behavior may reconcile the contrasted observations about the amplitude of crushing loss. This undesirable atmospheric contamination is negligible if grain fractions smaller than 150 mm are

  3. Cosmogenic Be-7 in grass of Maamora site

    International Nuclear Information System (INIS)

    El-khoukhi, T.; Fidah, M.; Oublaid, B.

    1994-01-01

    Be-7 is one of the radionuclides produced by the nuclear reactions of protons and alpha particulates of galactic and solar cosmic rays as well as the secondary neutrons produced during those reactions. it is submitted, as soon as it is produced, to the physical and chemical laws of the environment, such as air motions or the fixing to the atmospheric aerosols. In the framework of environmental radioactivity monitoring programme of Maamora site (Morocco), samples of grass were collected, prepared and analyzed using gamma spectrometry. The preparation consists of drying and ashing the grass. The detector used is coaxial Ge HP with 20% efficiency. Samples were counted for more than 50000 s. The activity of Be-7 calculated for samples collected in 10 km around Maamora site varies between 4 and 20 Bq/g of ashed grass. 3 refs. (author)

  4. Restriction of cosmic-ray acceleration, mechanisms by high-energy Be7/Be data

    International Nuclear Information System (INIS)

    Orth, C.D.; Buffington, A.; Mast, T.S.

    1979-01-01

    New high-energy cosmic-ray Be data indicate that the ratio Be 7 /Be drops by approximately a factor of two between 200 and 1500 MeV/nucleon. This result may provide a severe constraint for theories of cosmic-ray acceleration

  5. Study of the concentration of 7 Be in samples of rain water

    International Nuclear Information System (INIS)

    Quintero P, E.; Rojas M, V.P.

    2004-01-01

    This work shows the methodology carried out for the determination of 7 Be in samples of rain water and the obtained results of the concentration of having said radionuclide in this sampled matrix during the last five years in the Nuclear Center of Mexico. (Author)

  6. 3He(α,γ7Be cross section measured using complementary techniques

    Directory of Open Access Journals (Sweden)

    Carmona-Gallardo M.

    2014-03-01

    Full Text Available The astrophysical S-factor for the 3He(α,γ7Be reaction plays an important role in the Solar Standard Model and in the Big Bang Nucleosynthesis scenario. The advances from two recent experiments performed using complementary techniques at center of mass (C.M. energies between 1 and 3 MeV are discussed.

  7. Study of the 6He+9Be and 7Be+9Be collisions

    CERN Document Server

    Pires, K C C; Mukha, I; Moro, A M; Gómez-Camacho, J; Lépine-Szily, A; Guimarães, V; Assunção, M; de Faria, P N; Crema, E; Barioni, A; Mendes Junior, D R; Morcelle, V; Morais, M C; Pampa Condori, O; Mukherjee, S; Huyse, M; Ivanov, O; Leash, S; Pauwels, D; Ponsaers, J; Raabe, R; Smirnov, D; Stefanescu, I; Van Duppen, P; Angulok, C; Casarejosk, E; Loiseletk, M; Ryckwaertk, G; Martel, I; Sánchez-Benítez, A M; Grigorenko, L; Timofeyuk, N K

    2010-01-01

    We present elastic scattering angular distributions of the 6He+9Be and 7Be+9Be reactions at Elab =16.2 MeV and Elab =23.7 MeV respectively. The 6He+9Be measurements have been performed at the Pelletron Laboratory of the Institute of Physics of the University of Sao Paulo, Brazil, using the Radioactive Ion Beams in Brasil (RIBRAS) facility and the 7Be+9Be system has beenmeasured at CRC Radioactive Beam Facility at Louvain-la-Neuve,Belgium. An OpticalModel analysis has been performed to obtain the nuclear potentials for both systems. A coupled-channel calculation was performed for the 7Be+9Be system taking into account the coupling to the first excited state and breakup channels of the 7Be nucleus. Keywords: Radioctive Beams. Exotic Nuclei. Nuclear Halo. Long range absorption. Elastic Scattering. Optical potential. Coupled channels calculations. PACS: 25.60.-t,25.60.Bx,25.70.Bc,29.38.-c,24.10.Eq

  8. Post-acceleration of sup 7 Be at the Louvain-la-Neuve radioactive ion beam facility

    CERN Document Server

    Gaelens, M; Loiselet, M; Ryckewaert, G

    2003-01-01

    The development of an intense and pure post-accelerated sup 7 Be beam at Louvain-la-Neuve will be discussed. Given its properties (metallic nature, long half-life (53 days)) and the special beam parameters required (multi-charge ions, high purity), a range of special techniques had to be investigated. At Louvain-la-Neuve, sup 7 Be is produced by irradiating a lithium target with 30 mu A of 27 MeV protons and is extracted using offline chemical separation techniques. Because of the large amounts of activity required, the chemistry has to be adapted for use in hotcells. The ionization is performed with an Electron Cyclotron Resonance ion source with the sup 7 Be injected in the source by means of sputtering. Special techniques have to be used to prevent the beryllium atoms from being lost on the plasma chamber walls. A dedicated heated plasma chamber for the ion source was developed. The ionization efficiency was increased by studying the chemistry involved in the ion source. The atoms are ionized to the 1+ or ...

  9. In-situ buildup of cosmogenic isotopes at the earth`s surface: measurement of erosion rates and exposure times

    Energy Technology Data Exchange (ETDEWEB)

    Fifield, L K; Allan, G L; Stone, J O.H.; Evans, J M; Cresswell, R G; Ophel, T R [Australian National Univ., Canberra, ACT (Australia)

    1994-12-31

    Cosmic rays produce a number of nuclides in rocks that can be used to determine the geomorphic history of surfaces. The most useful are the radioactive isotopes {sup 10}Be (t{sub 1/2} = 1.5Ma), {sup 26}Al (0.7Ma) and {sup 36}Cl (0.3Ma). Within the top 2m of the surface, these are produced principally by fast neutrons. At greater depths, production is dominated by the capture of negative muons. Measurements of a single nuclide produced in situ can be used to determine total exposure times or erosion rates. The use of multiple nuclides with different half-lives makes it possible to determine more complex histories, such as exposures interrupted by periods of burial. At the ANU, all three of the isotopes above are being used to study a variety of problems in geomorphology and paleoclimatology, although to date, most of the work has concentrated on {sup 36}Cl. The accumulation of cosmogenic {sup 36}Cl in calcite (CaCO{sub 3}) provides a means of measuring erosion rates on limestone surfaces. Sensitivity is achieved over a wide range of erosion rates due to the high production rate of {sup 36}Cl in calcite (typically greater than 30 atoms/g/yr) and a detection limit of ca. 5000 atoms/g attainable with the ANU AMS system. The method is simplified by the predominance of Ca reactions (principally spallation) over other sources of {sup 36}Cl in calcite, and the ease of sample preparation. This presentation discuss the results of measurements of {sup 36}Cl in calcite from limestone samples from Australia and Papua New Guinea. Erosion rates derived from these measurements range from 3 microns per year (Australia) to over 200 microns per year in the New Guinea highlands. 3 refs.

  10. In-situ buildup of cosmogenic isotopes at the earth's surface: measurement of erosion rates and exposure times

    International Nuclear Information System (INIS)

    Fifield, L.K.; Allan, G.L.; Stone, J.O.H.; Evans, J.M.; Cresswell, R.G.; Ophel, T.R.

    1993-01-01

    Cosmic rays produce a number of nuclides in rocks that can be used to determine the geomorphic history of surfaces. The most useful are the radioactive isotopes 10 Be (t 1/2 = 1.5Ma), 26 Al (0.7Ma) and 36 Cl (0.3Ma). Within the top 2m of the surface, these are produced principally by fast neutrons. At greater depths, production is dominated by the capture of negative muons. Measurements of a single nuclide produced in situ can be used to determine total exposure times or erosion rates. The use of multiple nuclides with different half-lives makes it possible to determine more complex histories, such as exposures interrupted by periods of burial. At the ANU, all three of the isotopes above are being used to study a variety of problems in geomorphology and paleoclimatology, although to date, most of the work has concentrated on 36 Cl. The accumulation of cosmogenic 36 Cl in calcite (CaCO 3 ) provides a means of measuring erosion rates on limestone surfaces. Sensitivity is achieved over a wide range of erosion rates due to the high production rate of 36 Cl in calcite (typically greater than 30 atoms/g/yr) and a detection limit of ca. 5000 atoms/g attainable with the ANU AMS system. The method is simplified by the predominance of Ca reactions (principally spallation) over other sources of 36 Cl in calcite, and the ease of sample preparation. This presentation discuss the results of measurements of 36 Cl in calcite from limestone samples from Australia and Papua New Guinea. Erosion rates derived from these measurements range from 3 microns per year (Australia) to over 200 microns per year in the New Guinea highlands. 3 refs

  11. In-situ buildup of cosmogenic isotopes at the earth`s surface: measurement of erosion rates and exposure times

    Energy Technology Data Exchange (ETDEWEB)

    Fifield, L.K.; Allan, G.L.; Stone, J.O.H.; Evans, J.M.; Cresswell, R.G.; Ophel, T.R. [Australian National Univ., Canberra, ACT (Australia)

    1993-12-31

    Cosmic rays produce a number of nuclides in rocks that can be used to determine the geomorphic history of surfaces. The most useful are the radioactive isotopes {sup 10}Be (t{sub 1/2} = 1.5Ma), {sup 26}Al (0.7Ma) and {sup 36}Cl (0.3Ma). Within the top 2m of the surface, these are produced principally by fast neutrons. At greater depths, production is dominated by the capture of negative muons. Measurements of a single nuclide produced in situ can be used to determine total exposure times or erosion rates. The use of multiple nuclides with different half-lives makes it possible to determine more complex histories, such as exposures interrupted by periods of burial. At the ANU, all three of the isotopes above are being used to study a variety of problems in geomorphology and paleoclimatology, although to date, most of the work has concentrated on {sup 36}Cl. The accumulation of cosmogenic {sup 36}Cl in calcite (CaCO{sub 3}) provides a means of measuring erosion rates on limestone surfaces. Sensitivity is achieved over a wide range of erosion rates due to the high production rate of {sup 36}Cl in calcite (typically greater than 30 atoms/g/yr) and a detection limit of ca. 5000 atoms/g attainable with the ANU AMS system. The method is simplified by the predominance of Ca reactions (principally spallation) over other sources of {sup 36}Cl in calcite, and the ease of sample preparation. This presentation discuss the results of measurements of {sup 36}Cl in calcite from limestone samples from Australia and Papua New Guinea. Erosion rates derived from these measurements range from 3 microns per year (Australia) to over 200 microns per year in the New Guinea highlands. 3 refs.

  12. 3He(α, γ7Be cross section in a wide energy range

    Directory of Open Access Journals (Sweden)

    Szücs Tamás

    2017-01-01

    Full Text Available The reaction rate of the 3He(α,γ7 Be reaction is important both in the Big Bang Nucleosynthesis (BBN and in the Solar hydrogen burning. There have been a lot of experimental and theoretical efforts to determine this reaction rate with high precision. Some long standing issues have been solved by the more precise investigations, like the different S(0 values predicted by the activation and in-beam measurement. However, the recent, more detailed astrophysical model predictions require the reaction rate with even higher precision to unravel new issues like the Solar composition. One way to increase the precision is to provide a comprehensive dataset in a wide energy range, extending the experimental cross section database of this reaction. This paper presents a new cross section measurement between Ecm = 2.5 − 4.4 MeV, in an energy range which extends above the 7Be proton separation threshold.

  13. Using 7Be to document soil erosion on the weed plots

    International Nuclear Information System (INIS)

    Zhang Bo; Zhang Fengbao; Yang Mingyi

    2013-01-01

    Be tracing technology was applied to document soil erosion on the bare plot and weed plot, and compae soil erosion rate with the calculated rate. Results indicated that vegetation cover had obvious effect on the estimate of soil erosion rate on the weed plot using 7 Be measurement. Therefore, a factor of vegetation had been introduced into the Walling's model of converting 7 Be activity to soil erosion rate for estimating soil erosion rate on the weed slope surface. It was found that the soil erosion rates calculated by modified model were well close to the measured values on the weed plot, which illustrated that the modified model could be well used to estimate the rates of soil loss on the weed slope surface. These findings provide effective means for further study on the relationship between vegetation cover and soil erosion. (authors)

  14. Direct measurement of the partial decay energy of 7Be inner bremstrahlung spectrum

    International Nuclear Information System (INIS)

    Sanjeeviah, H.; Sanjeeviah, B.

    1978-01-01

    The inner bremsstrahlung spectrum accompanying orbital electron capture decay of 7 Be to the first excited state of 7 Li was measured in coincidence with 477 keV gamma rays. From the Jauch plot of the spectrum the partial decay energy was found to be 394 +- 16 keV. The shape factor of the inner bremsstrahlung spectrum close to the end point was accurately determined. It was found to be a constant X(1.001 +- 0.002) (author)

  15. Activity of the 7Be isotope in plants from south-west Finland

    International Nuclear Information System (INIS)

    Loennroth, T.; Kaellman, K.M.; Agren, D.; Lill, J.O.

    2007-01-01

    We report the measurements of 7 Be activity in nine vegetable species through the detection of its 477.6 keV γ-ray of 7 Li. The plants were grown 10 km south of the city of Turku in south-west Finland, located at approximately about 23E, 62N. The results show that nettle, salad and cucumber have activities that exceed the detection limit. (author)

  16. Cosmogenic helium and volatile-rich fluid in Sierra leone alluvial diamonds

    International Nuclear Information System (INIS)

    McConville, P.; Reynolds, J.H.

    1989-01-01

    Pursuant to the discovery elsewhere of cosmogenic 10 Be in alluvial diamond fragments from Zaire, noble gas measurements were made on two identical splits of a finely powdered, harshly acid-washed sample derived from selected (for clarity) fragments of a single alluvial diamond from Sierra Leone (sample LJA → L4 and L5). Essentially identical results were obtained for both splits. Isotopic ratios for Ar, Kr, and Xe were atmospheric and their elemental abundances were high relative to published data, owing to shock implantation in the crushing as verified in a supplementary experiment. No neon was detected above blank level. 3 He was exceptionally abundant, 4 He exceptionally depleted, possibly from the acid wash, and the ratio 3 He/ 4 He almost unprecedentedly high at an R/R a value of 246 ± 16. The results support the hypothesis that excess 3 He in diamonds is cosmogenic, although a cosmic-ray exposure of 5, 35, or (impossibly) 152 Ma for cyclic gardening of the sample to a maximum depth of 0, 4.6 m, or 20 m, respectively, is required. Troublesome for the cosmogenic hypothesis is a sample from very deep in the Finsch mine, South Africa, found by Zadnik et al (1987) to have an R/R a value of 1,000. This paper includes histograms of noble gas data published prior to mid-1988 for diamonds of known provenance. The Sierra Leone diamond studied in the supplementary experiment belongs to a distinct population of 40* Ar-rich diamonds consisting mostly of cubic diamonds for Zaire

  17. The production of cosmogenic isotopes in the earth's atmosphere and their inventories

    International Nuclear Information System (INIS)

    O'Brien, K.; de la Zerda Lerner, A.; Shea. M.A.; Smart, D.F.

    1991-01-01

    In this paper, production rates of cosmogenic isotopes in the Earth's atmosphere and their dependence on solar modulation and geomagnetic field intensity are calculated. Spallation cross sections were also obtained using the Silberberg-Tsao equations and solar modulation effects were calculated using the force-field model. The current geomagnetic field is treated in detail, and past magnetic fields are modeled based on the archeomagnetic record. Radiocarbon and radioberyllium inventories so obtained are in good agreement with current values. The neutrino-emitting radioactivity of the Earth's atmosphere is shown to add a negligible contribution to the flux from the Sun

  18. Tungsten isotopic compositions of iron meteorites: Chronological constraints vs. cosmogenic effects

    Science.gov (United States)

    Markowski, A.; Quitté, G.; Halliday, A. N.; Kleine, T.

    2006-02-01

    High-precision W isotopic compositions are presented for 35 iron meteorites from 7 magmatic groups (IC, IIAB, IID, IIIAB, IIIF, IVA, and IVB) and 3 non-magmatic groups (IAB, IIICD, and IIE). Small but resolvable isotopic variations are present both within and between iron meteorite groups. Variations in the 182W/ 184W ratio reflect either time intervals of metal-silicate differentiation, or result from the burnout of W isotopes caused by a prolonged exposure to galactic cosmic rays. Calculated apparent time spans for some groups of magmatic iron meteorites correspond to 8.5 ± 2.1 My (IID), 5.1 ± 2.3 My (IIAB), and 5.3 ± 1.3 My (IVB). These time intervals are significantly longer than those predicated from models of planetesimal accretion. It is shown that cosmogenic effects can account for a large part of the W isotopic variation. No simple relationship exists with exposure ages, compromising any reliable method of correction. After allowance for maximum possible cosmogenic effects, it is found that there is no evidence that any of the magmatic iron meteorites studied here have initial W isotopic compositions that differ from those of Allende CAIs [ ɛ182W = - 3.47 ± 0.20; [T. Kleine, K. Mezger, H. Palme, E. Scherer and C. Münker, Early core formation in asteroids and late accretion of chondrite parent bodies: evidence from 182Hf- 182W in CAIs, metal-rich chondrites and iron meteorites, Geochim. Cosmochim. Acta (in press)]. Cosmogenic corrections cannot yet be made with sufficient accuracy to obtain highly precise ages for iron meteorites. Some of the corrected ages nevertheless require extremely early metal-silicate segregation no later than 1 My after formation of CAIs. Therefore, magmatic iron meteorites appear to provide the best examples yet identified of material derived from the first planetesimals that grew by runaway growth, as modelled in dynamic simulations. Non-magmatic iron meteorites have a more radiogenic W isotopic composition than magmatic

  19. Cold rocks, hot sands: In-situ cosmogenic applications in Australia at ANTARES

    International Nuclear Information System (INIS)

    Fink, David; McKelvey, B.; Hannan, D.; Newsome, D.

    2000-01-01

    The ANTARES AMS facility at ANSTO is conducting a comprehensive program in the application of in-situ cosmogenic radionuclides based on strong university collaborations in the earth sciences. The program targets two major objectives: (1) to determine and improve the Quaternary glacial chronology of the Southern Hemisphere in support of global climate change studies; (2) to characterise the processes of surface weathering and landscape evolution in semi-arid regions of the Australian continent. An overview of the program is presented with preliminary results from the first phase of these studies

  20. Scaling in situ cosmogenic nuclide production rates using analytical approximations to atmospheric cosmic-ray fluxes

    Science.gov (United States)

    Lifton, Nathaniel; Sato, Tatsuhiko; Dunai, Tibor J.

    2014-01-01

    Several models have been proposed for scaling in situ cosmogenic nuclide production rates from the relatively few sites where they have been measured to other sites of interest. Two main types of models are recognized: (1) those based on data from nuclear disintegrations in photographic emulsions combined with various neutron detectors, and (2) those based largely on neutron monitor data. However, stubborn discrepancies between these model types have led to frequent confusion when calculating surface exposure ages from production rates derived from the models. To help resolve these discrepancies and identify the sources of potential biases in each model, we have developed a new scaling model based on analytical approximations to modeled fluxes of the main atmospheric cosmic-ray particles responsible for in situ cosmogenic nuclide production. Both the analytical formulations and the Monte Carlo model fluxes on which they are based agree well with measured atmospheric fluxes of neutrons, protons, and muons, indicating they can serve as a robust estimate of the atmospheric cosmic-ray flux based on first principles. We are also using updated records for quantifying temporal and spatial variability in geomagnetic and solar modulation effects on the fluxes. A key advantage of this new model (herein termed LSD) over previous Monte Carlo models of cosmogenic nuclide production is that it allows for faster estimation of scaling factors based on time-varying geomagnetic and solar inputs. Comparing scaling predictions derived from the LSD model with those of previously published models suggest potential sources of bias in the latter can be largely attributed to two factors: different energy responses of the secondary neutron detectors used in developing the models, and different geomagnetic parameterizations. Given that the LSD model generates flux spectra for each cosmic-ray particle of interest, it is also relatively straightforward to generate nuclide-specific scaling

  1. Production of selected cosmogenic radionuclides by muons; 1, Fast muons

    CERN Document Server

    Heisinger, B; Jull, A J T; Kubik, P W; Ivy-Ochs, S; Neumaier, S; Knie, K; Lazarev, V A; Nolte, E

    2002-01-01

    To investigate muon-induced nuclear reactions leading to the production of radionuclides, targets made of C/sub 9/H/sub 12/, SiO /sub 2/, Al/sub 2/O/sub 3/, Al, S, CaCO/sub 3/, Fe, Ni, Cu, Gd, Yb and Tl were irradiated with 100 and 190 GeV muons in the NA54 experimental setup at CERN. The radionuclide concentrations were measured with accelerator mass spectrometry and gamma -spectroscopy. Results are presented for the corresponding partial formation cross- sections. Several of the long-lived and short-lived radionuclides studied are also produced by fast cosmic ray muons in the atmosphere and at depths underground. Because of their importance to Earth sciences investigations, calculations of the depth dependence of production rates by fast cosmic ray muons have been made. (48 refs).

  2. 7Be content in rainfall and soil deposition in South American coastal ecosystems

    International Nuclear Information System (INIS)

    Cardoso, R.; Ayub, J. Juri; Anjos, Roberto Meigikos dos; Cid, Alberto Silva; Velasco, H.

    2011-01-01

    Full text: Research about input, circulation and accumulation of natural and anthropogenic radionuclides in terrestrial ecosystems allows examining sources, establishing time scales and elucidating environmental processes. Thinking this way, researchers at UFF and UNSL have applied short-lived particle-reactive tracers to understand the behaviour of species evolution, functioning and restorations of natural and semi-natural ecosystems as well as to investigate the patterns and frequency of disturbances due to modern global changes. This can be accomplished through a detailed understanding on the hydrology and water circulation pattern, soil characteristics, erosion, resuspension, reduction/oxidation, speciation, precipitation and accumulation, diagenetic processes and microbial activities. 7 Be is a natural radionuclide (Eγ = 477.6 keV, t 1 / 2 = 53.3 d), which originates in the upper atmosphere as a result of bombardment by cosmic rays. The global distribution of this radionuclide provides a valuable means for testing and validating global circulation models on short time-scales. Its removal from the atmosphere by wet or dry deposition provides a useful tool for developing and validation of models about transport processes from the troposphere to the land surface. Knowledge of site-specific atmospheric fluxes is also crucial to evaluate the impact of atmospherically delivered pollutants on terrestrial ecosystems. The distribution of South American lands on different latitudes and its diversified topography can influence the development and action of many atmospheric systems contributing to generate non-homogeneous climatic conditions in this region. Increasing anthropogenic loads can further modify the precipitation rates and hence the climate of this region. Therefore it is important to study intra-system and inter-system interactions in different South American terrestrial ecosystems. Since 2006, UNSL has been investigating the 7 Be contents in rainfall and

  3. Beam shaping assembly optimization for (7)Li(p,n)(7)Be accelerator based BNCT.

    Science.gov (United States)

    Minsky, D M; Kreiner, A J

    2014-06-01

    Within the framework of accelerator-based BNCT, a project to develop a folded Tandem-ElectroStatic-Quadrupole accelerator is under way at the Atomic Energy Commission of Argentina. The proposed accelerator is conceived to deliver a proton beam of 30mA at about 2.5MeV. In this work we explore a Beam Shaping Assembly (BSA) design based on the (7)Li(p,n)(7)Be neutron production reaction to obtain neutron beams to treat deep seated tumors. © 2013 Elsevier Ltd. All rights reserved.

  4. The behavior of 210Pb and 7Be in the atmosphere in Nagasaki

    International Nuclear Information System (INIS)

    Nakamura, M.; Fujiyasu, N.; Yoshikawa, I.; Takatsuji, T.

    2004-01-01

    Nagasaki is located in the western end of Japan, and first receives aerosol factors in Japan from the Eurasian Continent such as Asian dusts and directly almost with no mixing of the domestic factors. Since this geographically situation of Nagasaki area, we have measured the aerosol size and the concentration of 210 Pb and 7 Be adhering to aerosol. Seasonal variation of these data was analyzed combined with some weather data, the rainfall and the wind direction. We present and discuss some result from the analysis. (author)

  5. Glacial erosion of high-elevation low-relief summits on passive continental margins constrained by cosmogenic nuclides

    DEFF Research Database (Denmark)

    Andersen, Jane Lund; Egholm, David Lundbek; Knudsen, Mads Faurschou

    We present a new, extensive in-situ cosmogenic 10Be and 26Al dataset from high-elevation low-relief summits along Sognefjorden in Norway. Contrary to previous studies of high-elevation low-relief summits in cold regions, we find only limited cosmogenic nuclide inheritance in bedrock surfaces......, indicating that warm-based ice eroded the summits during the last glacial period. From the isotope concentrations we model denudation histories using a recently developed Monte Carlo Markov Chain inversion model (Knudsen et al, 2015). The model relies on the benthic d18O curve (Lisiecki and Raymo, 2005...

  6. Fluvial terrace dating using in situ cosmogenic {sup 21}Ne

    Energy Technology Data Exchange (ETDEWEB)

    Sexton, E. [Univ. of Illinois, Chicago, IL (United States); Caffee, M. [Lawrence Livermore National Lab., CA (United States)

    1994-12-01

    Through the analysis of cosmic-ray produced radio-genic and stable nuclide concentrations, specifically {sup 21}Ne, we hope to date certain geomorphic features located along the tributaries of the Colorado River in the Eastern Grand Canyon and the Rainbow Plateau located in Utah. During the Quaternary, the Colorado River system was fed by glacial melting and run-off from the Wind River and Colorado Mountain Ranges. Past periods of aggradation allowed the emplacement of terrace features from debris flow activity. By dating such features we can further constrain the timing of key events such as river down cutting, terrace genesis/exposure age, and rates of surface erosion. Knowing the age and elevation of each terrace we can determine an average rate of down cutting of this river system. This, in turn, will offer information regarding alpine glaciation which is a sensitive indicator of global climate change. Studying the relative concentrations of these isotopic species in surface rocks can be useful in researching glacial periodicity and the relationship between solar activity and climate.

  7. Precision measurement of the (7)Be solar neutrino interaction rate in Borexino.

    Science.gov (United States)

    Bellini, G; Benziger, J; Bick, D; Bonetti, S; Bonfini, G; Buizza Avanzini, M; Caccianiga, B; Cadonati, L; Calaprice, F; Carraro, C; Cavalcante, P; Chavarria, A; D'Angelo, D; Davini, S; Derbin, A; Etenko, A; Fomenko, K; Franco, D; Galbiati, C; Gazzana, S; Ghiano, C; Giammarchi, M; Goeger-Neff, M; Goretti, A; Grandi, L; Guardincerri, E; Hardy, S; Ianni, Aldo; Ianni, Andrea; Kobychev, V; Korablev, D; Korga, G; Koshio, Y; Kryn, D; Laubenstein, M; Lewke, T; Litvinovich, E; Loer, B; Lombardi, F; Lombardi, P; Ludhova, L; Machulin, I; Manecki, S; Maneschg, W; Manuzio, G; Meindl, Q; Meroni, E; Miramonti, L; Misiaszek, M; Montanari, D; Mosteiro, P; Muratova, V; Oberauer, L; Obolensky, M; Ortica, F; Pallavicini, M; Papp, L; Peña-Garay, C; Perasso, L; Perasso, S; Pocar, A; Raghavan, R S; Ranucci, G; Razeto, A; Re, A; Romani, A; Sabelnikov, A; Saldanha, R; Salvo, C; Schönert, S; Simgen, H; Skorokhvatov, M; Smirnov, O; Sotnikov, A; Sukhotin, S; Suvorov, Y; Tartaglia, R; Testera, G; Vignaud, D; Vogelaar, R B; von Feilitzsch, F; Winter, J; Wojcik, M; Wright, A; Wurm, M; Xu, J; Zaimidoroga, O; Zavatarelli, S; Zuzel, G

    2011-09-30

    The rate of neutrino-electron elastic scattering interactions from 862 keV (7)Be solar neutrinos in Borexino is determined to be 46.0±1.5(stat)(-1.6)(+1.5)(syst) counts/(day·100  ton). This corresponds to a ν(e)-equivalent (7)Be solar neutrino flux of (3.10±0.15)×10(9)  cm(-2) s(-1) and, under the assumption of ν(e) transition to other active neutrino flavours, yields an electron neutrino survival probability of 0.51±0.07 at 862 keV. The no flavor change hypothesis is ruled out at 5.0 σ. A global solar neutrino analysis with free fluxes determines Φ(pp)=6.06(-0.06)(+0.02)×10(10)  cm(-2) s(-1) and Φ(CNO)Mikheyev-Smirnov-Wolfenstein large mixing angle neutrino oscillation model is experimentally tested at low energy.

  8. Evaluating uncertainty in 7Be-based soil erosion estimates: an experimental plot approach

    Science.gov (United States)

    Blake, Will; Taylor, Alex; Abdelli, Wahid; Gaspar, Leticia; Barri, Bashar Al; Ryken, Nick; Mabit, Lionel

    2014-05-01

    Soil erosion remains a major concern for the international community and there is a growing need to improve the sustainability of agriculture to support future food security. High resolution soil erosion data are a fundamental requirement for underpinning soil conservation and management strategies but representative data on soil erosion rates are difficult to achieve by conventional means without interfering with farming practice and hence compromising the representativeness of results. Fallout radionuclide (FRN) tracer technology offers a solution since FRN tracers are delivered to the soil surface by natural processes and, where irreversible binding can be demonstrated, redistributed in association with soil particles. While much work has demonstrated the potential of short-lived 7Be (half-life 53 days), particularly in quantification of short-term inter-rill erosion, less attention has focussed on sources of uncertainty in derived erosion measurements and sampling strategies to minimise these. This poster outlines and discusses potential sources of uncertainty in 7Be-based soil erosion estimates and the experimental design considerations taken to quantify these in the context of a plot-scale validation experiment. Traditionally, gamma counting statistics have been the main element of uncertainty propagated and reported but recent work has shown that other factors may be more important such as: (i) spatial variability in the relaxation mass depth that describes the shape of the 7Be depth distribution for an uneroded point; (ii) spatial variability in fallout (linked to rainfall patterns and shadowing) over both reference site and plot; (iii) particle size sorting effects; (iv) preferential mobility of fallout over active runoff contributing areas. To explore these aspects in more detail, a plot of 4 x 35 m was ploughed and tilled to create a bare, sloped soil surface at the beginning of winter 2013/2014 in southwest UK. The lower edge of the plot was bounded by

  9. A new study of {sup 10}B(p,α){sup 7}Be reaction at low energies

    Energy Technology Data Exchange (ETDEWEB)

    Caciolli, A.; Depalo, R. [Universita di Padova, Dipartimento di Fisica e Astronomia, Padova (Italy); INFN, Sezione di Padova, Padova (Italy); Broggini, C.; Menegazzo, R. [INFN, Sezione di Padova, Padova (Italy); La Cognata, M.; Puglia, S.M.R.; Sergi, M.L. [Laboratori Nazionali del Sud, INFN, Catania (Italy); Lamia, L. [Universita degli Studi di Catania, Dipartimento di Fisica e Astronomia, Catania (Italy); Mou, L.; Rigato, V.; Rossi Alvarez, C. [Laboratori Nazionali di Legnaro, INFN, Legnaro (Italy); Romano, S.; Spitaleri, C. [Laboratori Nazionali del Sud, INFN, Catania (Italy); Universita degli Studi di Catania, Dipartimento di Fisica e Astronomia, Catania (Italy); Tumino, A. [Laboratori Nazionali del Sud, INFN, Catania (Italy); Universita degli Studi di Enna ' ' Kore' ' , Facolta di Ingegneria e Architettura, Enna (Italy)

    2016-05-15

    The {sup 10}B(p,α){sup 7}Be reaction is of great interest since it has many applications in different fields of research such as nuclear astrophysics, nuclear physics, and models of new reactors for clean energy generation. This reaction has been studied at the AN2000 accelerator of the INFN National Laboratories of Legnaro (LNL). The total cross section has been measured in a wide energy range (250-1182 keV) by using the activation method. The decays of the {sup 7}Be nuclei produced by the reaction were measured at the low counting facility of LNL by using two fully shielded high-purity germanium detectors. The present dataset shows a large discrepancy with respect to one of the previous data at the same energies and reduces the total uncertainty to the level of 6%. An R-matrix calculation has been performed on the present data using the parameters from previous Trojan Horse measurements for the 10 and 500 keV resonances. The present data do not lay on the R-matrix fit in one point suggesting the existence of a {sup 11}C level not observed yet. Further nuclear investigations are needed to confirm this hypothesis. (orig.)

  10. Neogene basin infilling from cosmogenic nuclides (10Be and 21Ne) in Atacama, Chile

    Science.gov (United States)

    Sanchez, Caroline; Regard, Vincent; Carretier, Sébastien; Riquelme, Rodrigo; Blard, Pierre-Henri; Campos, Eduardo; Brichau, Stéphanie; Lupker, Marteen; Hérail, Gérard

    2017-04-01

    In the hyperarid Atacama Desert, northern Chile, Neogene sediments host copper rich layers (exotic supergene mineralization). Current mines are excavated into relatively thin (production (quickly decreasing with depth) and disintegration (not for 21Ne). Sampling depths are at ˜100 m and at ˜50 m below the desert surface. First, 21Ne gives lower boundaries for upstream erosion rates or local sedimentation rate. These bounds are between 2 and 10 m/Ma, which is quite important for the area. The ratio between the two cosmogenic nuclides indicate a maximum burial age of 12 Ma (minimal erosion rate of 15 m/Ma) and is surprisingly similar from bottom to top, indicating a probable rapid infilling. We finally processed a Monte-Carlo inversion. This inversion helps taking into account the post-deposition muonic production of cosmogenic nuclides. Inversion results is dependent on the muonic production scheme. Interestingly, the similarity in concentrations from bottom to top pleads for quite low production at depth. Our data finally indicates a quick infilling between 12.5 and 10 Ma BP accounting for ˜100 m of deposition (minimum sedimentation rate of 40 m/Ma).

  11. New cosmogenic burial ages for Sterkfontein Member 2 Australopithecus and Member 5 Oldowan

    Science.gov (United States)

    Granger, Darryl E.; Gibbon, Ryan J.; Kuman, Kathleen; Clarke, Ronald J.; Bruxelles, Laurent; Caffee, Marc W.

    2015-06-01

    The cave infills at Sterkfontein contain one of the richest assemblages of Australopithecus fossils in the world, including the nearly complete skeleton StW 573 (`Little Foot') in its lower section, as well as early stone tools in higher sections. However, the chronology of the site remains controversial owing to the complex history of cave infilling. Much of the existing chronology based on uranium-lead dating and palaeomagnetic stratigraphy has recently been called into question by the recognition that dated flowstones fill cavities formed within previously cemented breccias and therefore do not form a stratigraphic sequence. Earlier dating with cosmogenic nuclides suffered a high degree of uncertainty and has been questioned on grounds of sediment reworking. Here we use isochron burial dating with cosmogenic aluminium-26 and beryllium-10 to show that the breccia containing StW 573 did not undergo significant reworking, and that it was deposited 3.67 +/- 0.16 million years ago, far earlier than the 2.2 million year flowstones found within it. The skeleton is thus coeval with early Australopithecus afarensis in eastern Africa. We also date the earliest stone tools at Sterkfontein to 2.18 +/- 0.21 million years ago, placing them in the Oldowan at a time similar to that found elsewhere in South Africa at Swartkans and Wonderwerk.

  12. Simulation of 7Be monthly depositions using normally available data on environmental monitoring and local meteorology

    International Nuclear Information System (INIS)

    Sakashita, Tetsuya; Nakamura, Yuji; Doi, Masahiro

    2003-01-01

    Monthly depositions of Beryllium-7 were simulated using normally available data on environmental monitoring and local meteorology over a 5-year period, from 1986 to 1990. The washout scheme of ApSimon et al., the constant dry deposition velocity (0.002 ms -1 ), and the rainout scheme of Kasibhatla et al. (K scheme) were used for simulation. Seasonal variations in the observed depositions were relatively well simulated by the present parameterization, however, there was a tendency for simulations to exceed the observed values, when heavy rain was measured. The revised parameterization of rainout scheme was introduced and improved the overestimation. The result may suggest that aerosols containing 7 Be are removed at a relatively high rate from the formation area of raindrops. (author)

  13. New method to evaluate the 7Li(p, n)7Be reaction near threshold

    International Nuclear Information System (INIS)

    Herrera, María S.; Moreno, Gustavo A.; Kreiner, Andrés J.

    2015-01-01

    In this work a complete description of the 7 Li(p, n) 7 Be reaction near threshold is given using center-of-mass and relative coordinates. It is shown that this standard approach, not used before in this context, leads to a simple mathematical representation which gives easy access to all relevant quantities in the reaction and allows a precise numerical implementation. It also allows in a simple way to include proton beam-energy spread affects. The method, implemented as a C++ code, was validated both with numerical and experimental data finding a good agreement. This tool is also used here to analyze scattered published measurements such as (p, n) cross sections, differential and total neutron yields for thick targets. Using these data we derive a consistent set of parameters to evaluate neutron production near threshold. Sensitivity of the results to data uncertainty and the possibility of incorporating new measurements are also discussed

  14. Late Pleistocene - Holocene development of the Tista megafan (West Bengal, India): 10Be cosmogenic and IRSL age constraints

    Science.gov (United States)

    Abrahami, Rachel; Huyghe, Pascale; van der Beek, Peter; Lowick, Sally; Carcaillet, Julien; Chakraborty, Tapan

    2018-04-01

    The Himalayan proximal foreland is characterized by Quaternary megafans, of which the formational mechanisms remain debated. The Tista megafan spreads over more than 16,000 km2 from the mountain front, where it is strongly incised, to the confluence of the Tista River with the Jamuna/Brahmaputra River, and stores sediments produced in the Sikkim Himalaya. We propose a scenario for the late Pleistocene - Holocene development of the Tista megafan based on new 10Be cosmogenic and Infra-Red Stimulated Luminescence (IRSL) age constraints, and discuss the main potential controls on its evolution. We suggest that two distal lobes developed successively downstream from a common proximal lobe. Deposition in the proximal lobe took place since at least ∼135 ka and incision began at 3.7-0.7+1.0 ka. The western distal lobe of the megafan was deposited early in the history of the megafan, when the Sikkim Himalaya catchment was drained by a tributary of the Ganga River, and was abandoned in the early Holocene (10-11 ka). The eastern, recent (active. Approximately synchronous incision between terraces in the hinterland and megafan surfaces suggests that incision propagated rapidly through the system. Our data do not evidence a direct link between incicion and tectonic processes. Aggradation and incision episodes appear more compatible with a climatic control, through changes in monsoon intensity and associated sediment flux. Depositional episodes in the Tista megafan, as elsewhere in the Himalaya and its foreland, appear to correlate with periods of strong monsoon precipitation and associated high sediment flux toward the foreland. Abandonment and incision of megafan surfaces and hinterland terraces appear associated to both the onset and the ending of phases of strong monsoon precipitation, during which the balance between water and sediment discharge changes rapidly.

  15. Holocene glacial history of the west Greenland Ice Sheet inferred from cosmogenic exposure ages and threshold lakes

    DEFF Research Database (Denmark)

    Larsen, Nicolaj Krog; Kjaer, K. H.; Colding, Sune Oluf

    2011-01-01

    In this study, we use a combination of 10Be exposure ages and threshold lakes to constrain the ice sheet history in Godthåbs- and Buksefjorden, west Greenland (63-64°N) during the Holocene. The 10Be cosmogenic exposure ages have been used to quantify both the ice retreat and thinning of the west...

  16. Adsorption and colloidal behaviour of carrier-free 7Be in aqueous solutions

    International Nuclear Information System (INIS)

    Benes, P.; Jiranek, V.

    1974-01-01

    The state of carrier-free 7 Be in aqueous nitrate solutions was studied by electrophoresis, centrifugation and dialysis. In solutions of pH 2+ cation. At pH > 4 hydrolysis of beryllium proceeds which results in the formation of BeOH + ions and Be(OH) 2 molecules. The larger part of these molecules is adsorbed on the surface of colloidal impurities present in the solution. The pseudocolloids thus formed are positively charged up to pH 11. In alkaline solutions (pH > 11), negatively charged pseudocolloids and anionic hydroxocomplexes of beryllium exist. Adsorption and desorption of carrier-free beryllium was studied on glass, plexiglass and polyethylene as a function of pH, age and ionic strength (NaNO 3 ) of the solution. It has been found that the adsorption begins at pH 3-5, passes through a maximum at pH 8-11 and decreases to a very low value at pH 14. Probable mechanismus of the adsorption were discussed. (orig.) [de

  17. Plot-slope soil erosion using 7Be measurement and rill fractal dimension

    International Nuclear Information System (INIS)

    Zhang Fengbao; Yang Mingyi

    2010-01-01

    In this study, we intended to use 7 Be measurement and fractal theory to quantify soil erosion process on slope. The results showed that contribution rate of inter rill erosion was more than that of rill erosion during early stage of rainfall. When it rained, contribution rate of rill erosion began to be higher than inter rill erosion and become the main part of erosion during medium stage of rainfall. The trend of contribution rate of inter rill erosion was growing and the rill erosion was lowering during late stage of rainfall. Rill fractal dimension on the plot slope was almost growing larger during rainfall,growing quickly during early stage of rainfall and slowly during the late stage. Correlations was positive between rill fractal dimension and total erosion amount, also positive between rill fractal dimension and rill erosion. The correlations was positive between rill fractal dimension variation and total erosion amount, also was positive between rill fractal dimension variation and rill erosion amount. The best correlation was observed between rill fractal dimension and rill erosion amount. These results indicated that the rill fractal dimension on the plot slope could represent the development process of rill,the complex degree of rill and the variation of soil erosion intensity on the entire slope. (authors)

  18. New Applications of Cosmogenic Radioactive Isotopes to Study Water Travel Times

    Science.gov (United States)

    Visser, A.; Thaw, M.; Deinhart, A.; Bibby, R. K.; Esser, B.

    2017-12-01

    The travel time of water moving through a landscape influences nutrient dynamics and biogeochemical cycles. Constraining water travel times helps to understand the functioning of the critical zone. Water travel times cannot be observed directly but can be constrained by measurements of cosmogenic radioactive isotopes. We studied a small (4.6 km2) subalpine (1660-2117 m) catchment in a Mediterranean climate (8 °C, 1200 mm/yr) in the California Sierra Nevada to assess subsurface water storage dynamics and investigate flow paths and flow velocities. We analyzed a combination of three cosmogenic radioactive isotopes with half-lives varying from 87 days (sulfur-35), 2.6 years (sodium-22) to 12.3 years (tritium) in precipitation and stream samples. Water stable isotopes and solute chemistry aided the interpretation of the cosmogenic isotopes. Tritium samples (1L) are analyzed by noble gas mass spectrometry after helium-3 accumulation. Samples for sulfur-35 and sodium-22 are collected by processing 20-1000 L of water through an anion and cation exchange column in-situ. Sulfur-35 is analyzed by liquid scintillation counting after chemical purification and precipitation. Sodium-22 is analyzed by gamma counting after eluting the cations into a 4L Marinelli beaker. Monthly collected precipitation samples show variability of deposition rate for tritium and sulfur-35. Sodium-22 levels in cumulative yearly precipitation samples are consistent with recent studies in the US and Japan. The observed variability of deposition rates complicates direct use as decaying age tracers. The level and variability of tritium in monthly stream samples indicate a mean residence time on the order of 10 years and only small contributions of younger water during high flow conditions. Sulfur-35 and sodium-22 concentrations were critically interpreted considering possible uptake by vegetation and cation exchange. Detections of sodium-22 confirm a small fraction of younger (water. Low concentrations

  19. Reconciling radiocarbon and ice core timescales over the Holocene - Cosmogenic radionuclides as synchronization tools

    Science.gov (United States)

    Muscheler, R.; Adolphi, F.; Mekhaldi, F.

    2015-12-01

    The atmospheric production rates of cosmogenic radionuclides, such as 14C and 10Be, vary globally due to external processes, namely the solar and geomagnetic modulation of the galactic cosmic ray flux as well as solar proton events. This signature is recorded in various archives such as ice cores (10Be) and tree-rings (14C). Hence, cosmogenic radionuclides offer a means to continuously assess timescale differences between two of the most widely used timescales in paleoclimatology - the radiocarbon and the ice core timescales. Short lived solar proton events additionally provide distinct marker horizons that allow synchronization of discrete horizons at annual precision. We will present a cosmogenic radionuclide based synchronization of the Greenland ice core timescale (GICC05, Svensson et al., 2008) and the radiocarbon timescale (IntCal13, Reimer et al., 2013) over the Holocene. This synchronization allows radiocarbon dated and ice core paleoclimate records to be compared on a common timescale at down to sub-decadal precision. We will compare these results to independent discrete isochrones obtained from tephrochronology and solar proton events. In addition, we will discuss implications for the accuracy and uncertainty estimates of GICC05 over the Holocene. Reimer, P. J., Bard, E., Bayliss, A., Beck, J. W., Blackwell, P. G., Bronk Ramsey, C., Buck, C. E., Cheng, H., Edwards, R. L., Friedrich, M., Grootes, P. M., Guilderson, T. P., Haflidason, H., Hajdas, I., Hatté, C., Heaton, T. J., Hoffmann, D. L., Hogg, A. G., Hughen, K. A., Kaiser, K. F., Kromer, B., Manning, S. W., Niu, M., Reimer, R. W., Richards, D. A., Scott, E. M., Southon, J. R., Staff, R. A., Turney, C. S. M., and van der Plicht, J.: IntCal13 and Marine13 Radiocarbon Age Calibration Curves 0-50,000 Years cal BP, Radiocarbon, 55, 1869-1887, 10.2458/azu_js_rc.55.16947, 2013. Svensson, A., Andersen, K. K., Bigler, M., Clausen, H. B., Dahl-Jensen, D., Davies, S. M., Johnsen, S. J., Muscheler, R., Parrenin

  20. An accelerator-based Boron Neutron Capture Therapy (BNCT) facility based on the 7Li(p,n)7Be

    Science.gov (United States)

    Musacchio González, Elizabeth; Martín Hernández, Guido

    2017-09-01

    BNCT (Boron Neutron Capture Therapy) is a therapeutic modality used to irradiate tumors cells previously loaded with the stable isotope 10B, with thermal or epithermal neutrons. This technique is capable of delivering a high dose to the tumor cells while the healthy surrounding tissue receive a much lower dose depending on the 10B biodistribution. In this study, therapeutic gain and tumor dose per target power, as parameters to evaluate the treatment quality, were calculated. The common neutron-producing reaction 7Li(p,n)7Be for accelerator-based BNCT, having a reaction threshold of 1880.4 keV, was considered as the primary source of neutrons. Energies near the reaction threshold for deep-seated brain tumors were employed. These calculations were performed with the Monte Carlo N-Particle (MCNP) code. A simple but effective beam shaping assembly (BSA) was calculated producing a high therapeutic gain compared to previously proposed facilities with the same nuclear reaction.

  1. Use of 7Be to document soil erosion associated with a short period of extreme rainfall

    International Nuclear Information System (INIS)

    Sepulveda, A.; Schuller, P.; Walling, D.E.; Castillo, A.

    2008-01-01

    Intensification and expansion of agricultural production since the 1970s have increased soil erosion problems in south-central Chile. Quantitative information on soil loss is needed for erosion risk assessment and to establish the effectiveness of improved land management practices. Since information from traditional sources, such as erosion plots, is limited, attention has been directed to the use of environmental radionuclides for documenting erosion rates. Cs-137 has been successfully utilised for this purpose, but only provides information on medium-term erosion rates. There is also a need to document event-related soil erosion. This paper outlines the basis for using 7 Be measurements to document short-term erosion and reports its successful use for quantifying the erosion that occurred within an arable field, as a result of a period of heavy rainfall (400 mm in 27 days) occurring in May 2005. The study field had been under a no-till, no-burning system for 18 years, but immediately prior to the period of heavy rainfall the harvest residues were burnt. The erosion recorded therefore reflected both the extreme nature of the rainfall and the effects of the burning in increasing surface runoff and erosion. The sampled area corresponded to that used previously by the authors to document the medium-term erosion rates associated with both conventional tillage and the subsequent switch to a no-till system. Comparisons between the erosion documented for the period of heavy rainfall in 2005 with these medium-term erosion rates permits some tentative conclusions regarding the importance of extreme events and the impact of burning in increasing the erosion associated with the no-till system

  2. Measurement of the 2H(7Be, 6Li)3He reaction rate and its contribution to the primordial lithium abundance

    Science.gov (United States)

    Li, Er-Tao; Li, Zhi-Hong; Yan, Sheng-Quan; Su, Jun; Guo, Bing; Li, Yun-Ju; Wang, You-Bao; Lian, Gang; Zeng, Sheng; Chen, Si-Zhe; Ma, Shao-Bo; Li, Xiang-Qing; He, Cao; Sun, Hui-Bin; Liu, Wei-Ping

    2018-04-01

    In the standard Big Bang nucleosynthesis (SBBN) model, the lithium puzzle has attracted intense interest over the past few decades, but still has not been solved. Conventionally, the approach is to include more reactions flowing into or out of lithium, and study the potential effects of those reactions which were not previously considered. 7Be(d, 3He)6Li is a reaction that not only produces 6Li but also destroys 7Be, which decays to 7Li, thereby affecting 7Li indirectly. Therefore, this reaction could alleviate the lithium discrepancy if its reaction rate is sufficiently high. However, there is not much information available about the 7Be(d, 3He)6Li reaction rate. In this work, the angular distributions of the 7Be(d, 3He)6Li reaction are measured at the center of mass energies E cm = 4.0 MeV and 6.7 MeV with secondary 7Be beams for the first time. The excitation function of the 7Be(d, 3He)6Li reaction is first calculated with the computer code TALYS and then normalized to the experimental data, then its reaction rate is deduced. A SBBN network calculation is performed to investigate its influence on the 6Li and 7Li abundances. The results show that the 7Be(d, 3He)6Li reaction has a minimal effect on 6Li and 7Li because of its small reaction rate. Therefore, the 7Be(d, 3He)6Li reaction is ruled out by this experiment as a means of alleviating the lithium discrepancy. Supported by National Natural Science Foundation of China (11375269, 11505117, 11490560, 11475264, 11321064), Natural Science Foundation of Guangdong Province (2015A030310012), 973 program of China (2013CB834406) and National key Research and Development Province (2016YFA0400502)

  3. Using Multiple Cosmogenic Nuclides to Investigate Ice Elevation Changes in the Ellsworth Mountains, Antarctica

    Science.gov (United States)

    Marrero, Shasta; Hein, Andy; Sugden, David; Woodward, John; Dunning, Stuart; Freeman, Stewart; Shanks, Richard

    2015-04-01

    Well-dated geologic data points provide important indicators that can be used for the reconstruction of ice sheet dynamics and as constraints in ice sheet models predicting future change. Cosmogenic nuclides, which accumulate in rocks exposed at the earth's surface, can be used to directly date the exposure age of the rock surfaces that have been created through glacial erosion or deposition. The technique requires a detailed understanding of the local geomorphology as well as awareness of the post-depositional processes that may affect the interpretation of exposure ages. Surface exposure ages (10Be, 26Al, 21Ne, and 36Cl) from local limestone bedrock and other glacially deposited exotic lithologies provide a history spanning from 0 to more than 1 million years in the Patriot, Independence, and Marble Hills in the southern Ellsworth Mountains, Antarctica. Using the new surface exposure ages combined with geomorphological mapping, we will discuss the implications for the glacial history of the southern Ellsworth Mountains.

  4. Ice Elevation Changes in the Ellsworth Mountains, Antarctica Using Multiple Cosmogenic Nuclides

    Science.gov (United States)

    Marrero, S.; Hein, A.; Sugden, D.; Woodward, J.; Dunning, S.; Reid, K.

    2014-12-01

    Well-dated geologic data points provide important indicators that can be used for the reconstruction of ice sheet dynamics and as constraints in ice sheet models predicting future change. Cosmogenic nuclides, which accumulate in rocks exposed at the earth's surface, can be used to directly date the exposure age of the rock surfaces that have been created through glacial erosion or deposition. The technique requires a detailed understanding of the local geomorphology as well as awareness of the post-depositional processes that may affect the interpretation of exposure ages. Initial surface exposure ages (10Be, 26Al, 21Ne, and 36Cl ) from local limestone bedrock and other glacially deposited exotic lithologies provide a history spanning from 0 to 1.1 Ma in the Patriot, Independence, and Marble Hills in the southern Ellsworth Mountains, Antarctica. Using the new surface exposure ages combined with geomorphological mapping, we will discuss the implications for the glacial history of the southern Ellsworth Mountains.

  5. An update on in situ cosmogenic {sup 14}C analysis at ETH Zuerich

    Energy Technology Data Exchange (ETDEWEB)

    Hippe, K., E-mail: hippe@erdw.ethz.ch [Institute of Geochemistry and Petrology, ETH Zuerich, Zuerich CH-8092 (Switzerland); Kober, F. [Institute of Geology, ETH Zuerich, Zuerich CH-8092 (Switzerland); Wacker, L. [Institute for Particle Physics, ETH Zuerich, Zuerich CH-8093 (Switzerland); Fahrni, S.M. [Institute for Particle Physics, ETH Zuerich, Zuerich CH-8093 (Switzerland); Department of Chemistry and Biochemistry, University of Bern, Bern CH-3012 (Switzerland); Ivy-Ochs, S. [Institute for Particle Physics, ETH Zuerich, Zuerich CH-8093 (Switzerland); Akcar, N.; Schluechter, C. [Institute of Geological Sciences, University of Bern, Bern CH-3012 (Switzerland); Wieler, R. [Institute of Geochemistry and Petrology, ETH Zuerich, Zuerich CH-8092 (Switzerland)

    2013-01-15

    We present the improved performance of the modified in situ cosmogenic {sup 14}C extraction system at ETH Zuerich. Samples are now processed faster (2 days in total) and are measured with a high analytical precision of usually <2% using the gas ion source of the MICADAS AMS facility. Measurements of the PP-4 standard sample show a good reproducibility and consistency with published values. Procedural blanks are very low at currently {approx}4.0 Multiplication-Sign 10{sup 414}C atoms. Analyses of samples from a {approx}300 year old rock avalanche prove that we can successfully apply in situ{sup 14}C exposure dating to very young surfaces. Additionally, we present a modified calculation scheme for in situ{sup 14}C concentrations which differs from that used for conventional radiocarbon dating. This new approach explicitly accounts for the characteristics of in situ{sup 14}C production.

  6. Constraining processes of landscape change with combined in situ cosmogenic 14C-10Be analysis

    Science.gov (United States)

    Hippe, Kristina

    2017-10-01

    Reconstructing Quaternary landscape evolution today frequently builds upon cosmogenic-nuclide surface exposure dating. However, the study of complex surface exposure chronologies on the 102-104 years' timescale remains challenging with the commonly used long-lived radionuclides (10Be, 26Al, 36Cl). In glacial settings, key points are the inheritance of nuclides accumulated in a rock surface during a previous exposure episode and (partial) shielding of a rock surface after the main deglaciation event, e.g. during phases of glacier readvance. Combining the short-lived in situ cosmogenic 14C isotope with 10Be dating provides a valuable approach to resolve and quantify complex exposure histories and burial episodes within Lateglacial and Holocene timescales. The first studies applying the in situ14C-10Be pair have demonstrated the great benefit from in situ14C analysis for unravelling complex glacier chronologies in various glacial environments worldwide. Moreover, emerging research on in situ14C in sedimentary systems highlights the capacity of combined in situ14C-10Be analysis to quantify sediment transfer times in fluvial catchments or to constrain changes in surface erosion rates. Nevertheless, further methodological advances are needed to obtain truly routine and widely available in situ14C analysis. Future development in analytical techniques has to focus on improving the analytical reproducibility, reducing the background level and determining more accurate muonic production rates. These improvements should allow extending the field of applications for combined in situ14C-10Be analysis in Earth surface sciences and open up a number of promising applications for dating young sedimentary deposits and the quantification of recent changes in surface erosion dynamics.

  7. Early Acheulean technology in the Rietputs Formation, South Africa, dated with cosmogenic nuclides.

    Science.gov (United States)

    Gibbon, Ryan J; Granger, Darryl E; Kuman, Kathleen; Partridge, Timothy C

    2009-02-01

    An absolute dating technique based on the build-up and decay of (26)Al and (10)Be in the mineral quartz provides crucial evidence regarding early Acheulean hominid distribution in South Africa. Cosmogenic nuclide burial dating of an ancient alluvial deposit of the Vaal River (Rietputs Formation) in the western interior of South Africa shows that coarse gravel and sand aggradation there occurred ca 1.57+/-0.22Ma, with individual ages of samples ranging from 1.89+/-0.19 to 1.34+/-0.22Ma. This was followed by aggradation of laminated and cross-bedded fine alluvium at ca 1.26+/-0.10Ma. The Rietputs Formation provides an ideal situation for the use of the cosmogenic nuclide burial dating method, as samples could be obtained from deep mining pits at depths ranging from 7 to 16 meters. Individual dates provide only a minimum age for the stone tool technology preserved within the deposits. Each assemblage represents a time averaged collection. Bifacial tools distributed throughout the coarse gravel and sand unit can be assigned to an early phase of the Acheulean. This is the first absolute radiometric dated evidence for early Acheulean artefacts in South Africa that have been found outside of the early hominid sites of the Gauteng Province. These absolute dates also indicate that handaxe-using hominids inhabited southern Africa as early as their counterparts in East Africa. The simultaneous appearance of the Acheulean in different parts of the continent implies relatively rapid technology development and the widespread use of large cutting tools in the African continent by ca 1.6Ma.

  8. 10Be systematics in the Tsangpo-Brahmaputra catchment: the cosmogenic nuclide legacy of the eastern Himalayan syntaxis

    Directory of Open Access Journals (Sweden)

    M. Lupker

    2017-08-01

    Full Text Available The Tsangpo-Brahmaputra River drains the eastern part of the Himalayan range and flows from the Tibetan Plateau through the eastern Himalayan syntaxis downstream to the Indo-Gangetic floodplain and the Bay of Bengal. As such, it is a unique natural laboratory to study how denudation and sediment production processes are transferred to river detrital signals. In this study, we present a new 10Be data set to constrain denudation rates across the catchment and to quantify the impact of rapid erosion within the syntaxis region on cosmogenic nuclide budgets and signals. The measured 10Be denudation rates span around 2 orders of magnitude across individual catchments (ranging from 0.03 to > 4 mm yr−1 and sharply increase as the Tsangpo-Brahmaputra flows across the eastern Himalaya. The increase in denudation rates, however, occurs  ∼  150 km downstream of the Namche Barwa–Gyala Peri massif (NBGPm, an area which has been previously characterized by extremely high erosion and exhumation rates. We suggest that this downstream lag is mainly due to the physical abrasion of coarse-grained, low 10Be concentration, landslide material produced within the syntaxis that dilutes the upstream high-concentration 10Be flux from the Tibetan Plateau only after abrasion has transferred sediment to the studied sand fraction. A simple abrasion model produces typical lag distances of 50 to 150 km compatible with our observations. Abrasion effects reduce the spatial resolution over which denudation can be constrained in the eastern Himalayan syntaxis. In addition, we also highlight that denudation rate estimates are dependent on the sediment connectivity, storage, and quartz content of the upstream Tibetan Plateau part of the catchment, which tends to lead to an overestimation of downstream denudation rates. While no direct 10Be denudation measurements were made in the syntaxis, the dilution of the upstream 10Be signal, measured in Tsangpo

  9. Short-term seasonal variability in 7Be wet deposition in a semiarid ecosystem of central Argentina

    International Nuclear Information System (INIS)

    Juri Ayub, J.; Di Gregorio, D.E.; Velasco, H.; Huck, H.; Rizzotto, M.; Lohaiza, F.

    2009-01-01

    The 7 Be wet deposition has been intensively investigated in a semiarid region at San Luis Province, Argentina. From November 2006 to May 2008, the 7 Be content in rainwater was determined in 58 individual rain events, randomly comprising more than 50% of all individual precipitations at the sampling period. 7 Be activity concentration in rainwater ranged from 0.7 ± 0.3 Bq l -1 to 3.2 ± 0.7 Bq l -1 , with a mean value of 1.7 Bq l -1 (sd = 0.53 Bq l -1 ). No relationship was found between 7 Be content in rainwater and (a) rainfall amount, (b) precipitation intensity and (c) elapsed time between events. 7 Be ground deposition was found to be well correlated with rainfall amount (R = 0.92). For the precipitation events considered, the 7 Be depositional fluxes ranged from 1.1 to 120 Bq m -2 , with a mean value of 32.7 Bq m -2 (sd = 29.9 Bq m -2 ). The annual depositional flux was estimated at 1140 ± 120 Bq m -2 y -1 . Assuming the same monthly deposition pattern and that the 7 Be content in soil decreases only through radioactive decay, the seasonal variation of 7 Be areal activity density in soil was estimated. Results of this investigation may contribute to a valuable characterization of 7 Be input in the explored semiarid ecosystem and its potential use as tracer of environmental processes.

  10. Study of the 10B(p,α)7Be Reaction through the Indirect Trojan Horse Method

    International Nuclear Information System (INIS)

    Puglia, S. M. R.; Romano, S.; Lamia, L.; Spitaleri, C.; Cherubini, S.; Gulino, M.; La Cognata, M.; Pizzone, R. G.; Rapisarda, G. G.; Sergi, M. L.; Tudisco, S.; Del Santo, M. G.; Carlin, N.; Souza, F.; Szanto de Toledo, A.; Kroha, V.; Kubono, S.; Wakabayashi, Y.; Yamaguchi, H.; Li, C.

    2010-01-01

    The 10 B(p,α) 7 Be reaction is the main responsible for 10 B destruction in stellar interior. In such environments the process takes places mainly through a resonant state of the compound 11 C nucleus. The 10 B(p,α) 7 Be reaction has been studied by means of the Trojan Horse Method using the 2 H( 10 B,α 7 Be)n three-body reaction. The experiment was performed at the Laboratori Nazionali del Sud in Catania. The 10 B(p,α) 7 Be reaction cross section has been extracted at low neutron momentum.

  11. Applications of cosmogenic radio-isotopes, 10Be, 26Al and 36CI in the Earth Sciences using AMS at ANSTO

    International Nuclear Information System (INIS)

    Fink, D.; Elliot, G.

    1997-01-01

    Production of long-lived cosmogenic radionuclides (CRN) is dominated by cosmic ray interaction in the upper atmosphere. Through atmospheric transport and precipitation, they become distributed over the Earth's surface, and participate in various geochemical and geophysical global processes. An alternate production mode of CRNs is in the Earth's lithosphere, particularly in exposed rocks and surfaces. The production rate of these in-situ produced CRNs depends primarily on the reaction mode and type of target material. Although production is small - a few tens of atoms per gram per year - the built-up in concentration even after a few thousand years of exposure can be measured using the technique of Accelerator Mass Spectrometry. Concentrations of in situ nuclides in the near-surface zone allows a 'surface exposure history' to be estimated resulting in a measure of exposure ages and erosion rates. With a range in half-lives from 0.3-1.5 Ma, in-situ produced CRNs are ideally suited as geochronometers and tracers in Quaternary geomorphology related to paleoclimate change. This paper will briefly outline principles and techniques of 10 Be, 26 AI and 36 CI in-situ methods and describe Some of the above projects related to the unique geomorphology of the Australian and Antarctic continents

  12. Reconstructing temperatures in the Maritime Alps, Italy, since the Last Glacial Maximum using cosmogenic noble gas paleothermometry

    Science.gov (United States)

    Tremblay, Marissa; Spagnolo, Matteo; Ribolini, Adriano; Shuster, David

    2016-04-01

    The Gesso Valley, located in the southwestern-most, Maritime portion of the European Alps, contains an exceptionally well-preserved record of glacial advances during the late Pleistocene and Holocene. Detailed geomorphic mapping, geochronology of glacial deposits, and glacier reconstructions indicate that glaciers in this Mediterranean region responded to millennial scale climate variability differently than glaciers in the interior of the European Alps. This suggests that the Mediterranean Sea somehow modulated the climate of this region. However, since glaciers respond to changes in temperature and precipitation, both variables were potentially influenced by proximity to the Sea. To disentangle the competing effects of temperature and precipitation changes on glacier size, we are constraining past temperature variations in the Gesso Valley since the Last Glacial Maximum (LGM) using cosmogenic noble gas paleothermometry. The cosmogenic noble gases 3He and 21Ne experience diffusive loss from common minerals like quartz and feldspars at Earth surface temperatures. Cosmogenic noble gas paleothermometry utilizes this open-system behavior to quantitatively constrain thermal histories of rocks during exposure to cosmic ray particles at the Earth's surface. We will present measurements of cosmogenic 3He in quartz sampled from moraines in the Gesso Valley with LGM, Bühl stadial, and Younger Dryas ages. With these 3He measurements and experimental data quantifying the diffusion kinetics of 3He in quartz, we will provide a preliminary temperature reconstruction for the Gesso Valley since the LGM. Future work on samples from younger moraines in the valley system will be used to fill in details of the more recent temperature history.

  13. Long-term background denudation rates of southern and southeastern Brazilian watersheds estimated with cosmogenic 10Be

    Science.gov (United States)

    Sosa Gonzalez, Veronica; Bierman, Paul R.; Fernandes, Nelson F.; Rood, Dylan H.

    2016-09-01

    In comparison to humid temperate regions of the Northern Hemisphere, less is known about the long-term (millennial scale) background rates of erosion in Southern Hemisphere tropical watersheds. In order to better understand the rate at which watersheds in southern and southeastern Brazil erode, and the relationship of that erosion to climate and landscape characteristics, we made new measurements of in situ produced 10Be in river sediments and we compiled all extant measurements from this part of the country. New data from 14 watersheds in the states of Santa Catarina (n = 7) and Rio de Janeiro (n = 7) show that erosion rates vary there from 13 to 90 m/My (mean = 32 m/My; median = 23 m/My) and that the difference between erosion rates of basins we sampled in the two states is not significant. Sampled basin area ranges between 3 and 14,987 km2, mean basin elevation between 235 and 1606 m, and mean basin slope between 11 and 29°. Basins sampled in Rio de Janeiro, including three that drain the Serra do Mar escarpment, have an average basin slope of 19°, whereas the average slope for the Santa Catarina basins is 14°. Mean basin slope (R2 = 0.73) and annual precipitation (R2 = 0.57) are most strongly correlated with erosion in the basins we studied. At three sites where we sampled river sand and cobbles, the 10Be concentration in river sand was greater than in the cobbles, suggesting that these grain sizes are sourced from different parts of the landscape. Compiling all cosmogenic 10Be-derived erosion rates previously published for southern and southeastern Brazil watersheds to date (n = 76) with our 14 sampled basins, we find that regional erosion rates (though low) are higher than those of watersheds also located on other passive margins including Namibia and the southeastern North America. Brazilian basins erode at a pace similar to escarpments in southeastern North America. Erosion rates in southern and southeastern Brazil are directly and positively related to

  14. Erosion rates and landscape evolution of the lowlands of the Upper Paraguay river basin (Brazil) from cosmogenic 10Be

    Science.gov (United States)

    Pupim, Fabiano do Nascimento; Bierman, Paul R.; Assine, Mario Luis; Rood, Dylan H.; Silva, Aguinaldo; Merino, Eder Renato

    2015-04-01

    The importance of Earth's low sloping areas in regard to global erosion and sediment fluxes has been widely and vigorously debated. It is a crucial area of research to elucidate geologically meaningful rates of land-surface change and thus the speed of element cycling on Earth. However, there are large portions of Earth where erosion rates have not been well or extensively measured, for example, the tropical lowlands. The Cuiabana lowlands are an extensive low-altitude and low-relief dissected metamorphic terrain situated in the Upper Paraguay river basin, central-west Brazil. Besides exposures of highly variable dissected metamorphic rocks, flat residual lateritic caps related to a Late Cenozoic planation surface dominate interfluves of the Cuiabana lowlands. The timescale over which the lowlands evolved and the planation surface developed, and the rate at which they have been modified by erosion, are poorly known. Here, we present measurements of in situ produced cosmogenic 10Be in outcropping metamorphic bedrock and clastic-lateritic caps to quantify rates of erosion of the surface and associated landforms in order to better understand the Quaternary landscape evolution of these lowlands. Overall, slow erosion rates (mean 10 m/Ma) suggest a stable tectonic environment in these lowlands. Erosion rates vary widely between different lithologies (range 0.57 to 28.3 m/Ma) consistent with differential erosion driving regional landform evolution. The lowest erosion rates are associated with the low-relief area (irregular plains), where clastic-laterite (mean 0.67 m/Ma) and quartzite (mean 2.6 m/Ma) crop out, whereas the highest erosion rates are associated with dissection of residual hills, dominated by metasandstone (mean 11.6 m/Ma) and phyllite (mean 27.6 m/Ma). These data imply that the Cuiabana lowland is comprised of two dominant landform sets with distinct and different dynamics. Because the planation surface (mostly lowlands) is lowering and losing mass more

  15. Travel Times of Water Derived from Three Naturally Occurring Cosmogenic Radioactive Isotopes

    Science.gov (United States)

    Visser, Ate; Thaw, Melissa; Deinhart, Amanda; Bibby, Richard; Esser, Brad

    2017-04-01

    Hydrological travel times are studied on scales that span six orders of magnitude, from daily event water in stream flow to pre-Holocene groundwater in wells. Groundwater vulnerability to contamination, groundwater surface water interactions and catchment response are often focused on "modern" water that recharged after the introduction of anthropogenic tritium in precipitation in 1953. Shorter residence times are expected in smaller catchments, resulting in immediate vulnerability to contamination. We studied a small (4.6 km2) alpine (1660-2117 m) catchment in a Mediterranean climate (8 ˚ C, 1200 mm/yr) in the California Sierra Nevada to assess subsurface storage and investigate the response to the recent California drought. We analyzed a combination of three cosmogenic radioactive isotopes with half-lives varying from 87 days (sulfur-35), 2.6 years (sodium-22) to 12.3 years (tritium) in precipitation and stream samples. Tritium samples (1 L) are analyzed by noble gas mass spectrometry after helium-3 accumulation. Samples for sulfur-35 and sodium-22 are collected by processing 20-1000 L of water through an anion and cation exchange column in-situ. Sulfur-35 is analyzed by liquid scintillation counting after chemical purification and precipitation. Sodium-22 is analyzed by gamma counting after eluting the cations into a 4L Marinelli beaker. Monthly collected precipitation samples show variability of deposition rate for tritium and sulfur-35. Sodium-22 levels in cumulative yearly precipitation samples are consistent with recent studies in the US and Japan. The observed variability of deposition rates complicates direct estimation of stream water age fractions. The level and variability of tritium in monthly stream samples indicate a mean residence time on the order of 10 years and only small contributions of younger water during high flow conditions. Estimates of subsurface storage are in agreement with estimates from geophysical studies. Detections of sodium-22

  16. Time lag between the tropopause height and the levels of 7Be concentration in near surface air

    Directory of Open Access Journals (Sweden)

    Melas D.

    2012-04-01

    Full Text Available The concentration of 7Be at near surface air has been determined over 2009, a year of a deep solar minimum, in the region of Thessaloniki, Greece at 40°62′ N, 22°95'E. In geomagnetic latitudes over 40° N, the elevation of the tropopause during the warm summer months and the vertical exchange of air masses within the troposphere cause greater mixture of the air masses resulting in higher concentration levels for 7Be in surface air. The positive correlation between the monthly activity concentration of 7Be and the tropopause height (0.94, p < 0.0001, and also between 7Be concentration and the temperature T (°C (R = 0.97, p < 0.001, confirm that the increased rate of vertical transport within the troposphere, especially during warmer summer months, has as a result the descent to surface of air masses enriched in 7Be. However, the 7Be concentration levels in near surface air are not expected to respond immediately to the change of elevation of the tropopause. It was found that there's a time lag of ~ 3 days between the change in the daily surface concentrations of 7Be the change in the elevation of the tropopause.

  17. Calculation of the rockwall recession rate of a limestone cliff, affected by rockfalls, using cosmogenic chlorine-36. Case study of the Montsec Range (Eastern Pyrenees, Spain)

    Science.gov (United States)

    Domènech, Guillem; Corominas, Jordi; Mavrouli, Olga; Merchel, Silke; Abellán, Antonio; Pavetich, Stefan; Rugel, Georg

    2018-04-01

    Cliff erosion may be a major problem in settled areas affecting populations and producing economic and ecological losses. In this paper we present a procedure to calculate the long-term retreat rate of a cliff affected by rockfalls in the Montsec Range, Eastern Pyrenees (Spain). It is composed of low, densely fractured limestones; and the rockwall is affected by rockfalls of different sizes. The rockfall scars are clearly distinguishable by their regular boundaries and by their orange colour, which contrast with the greyish old reference surface (S0) of the cliff face. We have dated different stepped surfaces of the rockwall, including S0, using cosmogenic 36Cl. The total amount of material released by rockfall activity was calculated using a high definition point cloud of the slope face obtained with a terrestrial laser scanner (TLS). The present rockwall surface has been subtracted from the reconstructed old cliff surface. This has allowed the calculation of the total volume released by rockfalls and of the retreat rate. The latter ranges from 0.31 to 0.37 mm·a- 1. This value is of the same order of magnitude as that obtained by other researchers in neighbouring regions in Spain, having similar geology and affected by rockfalls.

  18. On the Determination of the 7Be(n, α)4He Reaction Cross Section at BBN Energies

    Science.gov (United States)

    Lamia, L.; Spitaleri, C.; Bertulani, C. A.; Hou, S. Q.; La Cognata, M.; Pizzone, R. G.; Romano, S.; Sergi, M. L.; Tumino, A.

    2017-12-01

    7Be destruction channels are currently a matter of study because of their influence on the 7Li cosmological abundances. Here, we determine the cross section of the (n, α) reaction by using Trojan Horse experimental data for the 7Li(p, α)4He reaction and correcting for Coulomb effects. The deduced 7Be(n, α)4He data overlap with the Big Bang nucleosynthesis energies and the deduced reaction rate allows us to evaluate the corresponding cosmological implications.

  19. The Trojan Horse Method application on the 10B(p,α0)7Be reaction cross section measurements

    Science.gov (United States)

    Cvetinović, A.; Spitaleri, C.; Spartá, R.; Rapisarda, G. G.; Puglia, S. M.; La Cognata, M.; Cherubini, S.; Guardo, G. L.; Gulino, M.; Lamia, L.; Pizzone, R. G.; Romano, S.; Sergi, M. L.

    2018-01-01

    The 10B(p,α0)7Be reaction cross section has been measured in an wide energy range from 2.2 MeV down to 3 keV in a single experiment applying THM. Optimized experimental set-up ensured good energy resolution leading to a good separation of α0 and α1 contributions to the cross section coming from the 7Be ground and first excited state, respectively.

  20. Time lag between the tropopause height and the levels of 7Be concentration in near surface air

    Science.gov (United States)

    Ioannidou, A.; Vasileiadis, A.; Melas, D.

    2012-04-01

    The concentration of 7Be at near surface air has been determined over 2009, a year of a deep solar minimum, in the region of Thessaloniki, Greece at 40°62' N, 22°95'E. In geomagnetic latitudes over 40° N, the elevation of the tropopause during the warm summer months and the vertical exchange of air masses within the troposphere cause greater mixture of the air masses resulting in higher concentration levels for 7Be in surface air. The positive correlation between the monthly activity concentration of 7Be and the tropopause height (0.94, p rate of vertical transport within the troposphere, especially during warmer summer months, has as a result the descent to surface of air masses enriched in 7Be. However, the 7Be concentration levels in near surface air are not expected to respond immediately to the change of elevation of the tropopause. It was found that there's a time lag of ~ 3 days between the change in the daily surface concentrations of 7Be the change in the elevation of the tropopause.

  1. Atmospheric deposition and soil vertical distribution of {sup 7}Be in a semiarid region of central Argentina

    Energy Technology Data Exchange (ETDEWEB)

    Lohaiza, Flavia A.; Velasco, Hugo; Ayub, Jimena Juri; Rizzotto, Marcos; Valladares, Diego L. [Grupo de Estudios Ambientales, Instituto de Matematica Aplicada San Luis, Universidad Nacional de San Luis - CONICET, Ejercito de los Andes 950, D5700HHW San Luis (Argentina)

    2014-07-01

    Beryllium-7 is a potentially powerful tracer of soil erosion but poor information on {sup 7}Be atmospheric deposition and associated soil inventories in a semiarid region of Central Argentina exists. We estimated the {sup 7}Be atmospheric wet deposition and {sup 7}Be inventory in undisturbed soils north of the City of San Luis (S 33 deg. 9'; W 66 deg. 16') and explored its seasonal variation. Rain and soil samples were collected during 2006-2008 and 2009-2012, respectively. The atmospheric wet deposition was estimated considering both the mean activity concentration in rainwater and the precipitation regime of the region. Using the assessed monthly wet deposition of {sup 7}Be, the expected {sup 7}Be areal activity in soil was estimated applying a simple model. These estimated values were confronted with the experimental measurements in soil. The {sup 7}Be rainwater activity concentration ranged from 0.7 to 3.2 Bq l{sup -1}, with a mean of 1.7 Bq l{sup -1} (sd = 0.53 Bq l{sup -1}). A good linear relationship between {sup 7}Be wet deposition and rain magnitude was obtained (R=0.92, p<0.0001). The wet deposition on soil ranged from 1.1 to 120 Bq m{sup -2} with a mean value of 32.7 Bq m-2 (sd = 29.9 Bq m-2). The annual depositional flux was estimated at 1140 ± 120 Bq m{sup -2} y{sup -1}. The {sup 7}Be mass activity (Bq kg{sup -1}) values in soil samples in the wet period (November-April) were higher than in the dry period (May-October). A typical decreasing exponential function of {sup 7}Be areal activity (Bq m{sup -2}) with soil mass depth (kg m{sup -2}) was found and the distribution parameters for each month were determined. The minimum value of areal activity was 51 Bq m{sup -2} in August, reaching the maximum of 438 Bq m{sup -2} in February. The relaxation mass depth ranged from 2.9 kg m{sup -2} in March to 1.3 kg m{sup -2} in August. The confrontation of experimental measurements in soil with the estimated values using the model showed a good agreement

  2. A comment on the 7Be(p,γ)8B cross section and the solar neutrino problem

    International Nuclear Information System (INIS)

    Barker, F.C.; Spear, R.H.

    1986-02-01

    Evidence is presented which indicates that the accepted value for the cross section of the 7 Be(p,γ) 8 B reaction at stellar energies is probably too large. It is suggested that the accepted value of the 7 Li(d,p) 8 Li cross section, which has been used for normalization purposes, is too large; that the accepted value for the ratio of the 7 Be(p,γ) 8 B and 7 Li(d,p) 8 Li cross sections is too large; and that the energy dependence used to extrapolate to stellar energies from the higher energies at which measurements have been made is inaccurate. The consequent reduction of the 7 Be(p,γ) 8 B cross section by about 30% would not be sufficient to resolve the solar neutrino problem but would significantly lessen the discrepancy between observation and calculation

  3. 7Be in soil, deposited dust and atmospheric air and its using to infer soil erosion along Alexandria region, Egypt.

    Science.gov (United States)

    Saleh, I H; Abdel-Halim, A A

    2017-06-01

    This study investigated the radioactivity behavior of 7 Be in surface soil, airborne and deposited dust along Alexandria region in Egypt. The results obtained were used to predict scavenging processes of 7 Be from surface soil to infer soil erosion and land vulnerable to accelerated sea-level rise. The areal activity concentrations of 7 Be in surface soil were investigated in 30 undisturbed sites and 7 Be inventories were determined via deposited dust in 10 locations. Results of the former were found to be ranged from 78 Bq/m 2 to 104 Bq/m 2 . High levels were observed in western sites associated with high dust deposition rate. On the other hand, low levels were found in the eastern sites, those may be attributed to scavenging processes such as land erosion toward the direction to the sea. The effective removal rates of 7 Be were calculated using the box-model, showing a broad special trend of inventories generally decreasing eastwards. The scavenging rates were ranged between 3.13 yr -1 in western sites to 5.34 yr -1 in eastern ones which denote that the east of the city suffers from rapid soil erosion. The airborne 7 Be was monthly monitored along the period from October 2014 to September 2015 through one site located at the mid of the city. The results revealed lower values in winter and autumn than in summer and spring ranged between 6.2 mBq/m 3 and 10.5 mBq/m 3 . These levels are comparable with that in other world regions and the seasonal variations are associated with the prevailing climatic conditions in Alexandria region. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Cycling of 7Be and 210Pb in a high DOC, shallow, turbid estuary of south-east Texas

    International Nuclear Information System (INIS)

    Baskaran, M.; Ravichandran, M.; Bianchi, T.S.

    1997-01-01

    The Sabine-Neches estuary is a shallow, turbid estuary in south-east Texas with high concentrations of dissolved organic carbon (DOC). The sediment inventory of 210 Pb and 239 , 240 Pu indicates that only a fraction of the particle-associated nuclides that reach the estuary were retained in the sediment. To better understand the cause for this low-sediment inventory of particle-reactive nuclides, 7 Be and 210 Pb concentrations have been measured in the dissolved and particulate phases, in addition to the DOC and suspended particle concentrations. The ratios of dissolved to particulate concentrations of 7 Be and 210 Pb were generally higher than in most other coastal waters. The dissolved residence times of 7 Be and 210 Pb (accounting for riverine input) varied between 0.6 and 9.6 days and 1.7 and 9.8 days, respectively. Distribution coefficients (Kd) ranged between 1500 and 87 100 cm 3 g -1 for 7 Be and 2600 and 37 000 cm 3 g -1 for 210 Pb. These K d s are lower than those reported for most coastal waters. There was no significant correlation between suspended particle concentration and K d of either 7 Be and 210 Pb; this has been observed for many other particle-reactive nuclides, suggesting that particle is not the primary controlling variable for the removal of particle-reactive nuclides in these high DOC waters. The average particle residence time in this estuary is ∼ 2 days. The relatively low K d values, longer dissolved residence times of 7 Be and 210 Pb, longer particle residence times and shorter hydraulic residence times compared to other coastal areas, result in only a partial removal of particle-reactive radionuclides in this estuary. (author)

  5. Cross-section of the reaction {sup 7}Li(p,n){sup 7}Be close to the threshold

    Energy Technology Data Exchange (ETDEWEB)

    Shorin, V S [Institute of Physics and Power Engineering, Obninsk (Russian Federation)

    1997-06-01

    The status of data on the cross-section of the reaction {sup 7}Li(p,n){sup 7}Be close to the threshold is reviewed. On the basis of recent data on the cross-section of the inverse reaction {sup 7}Be(n,p){sup 7}Li and certain theoretical models, an evaluation is performed of the total cross-section of the {sup 7}Li(p,n)-reaction in the proton energy region up to 2 MeV. (author). 16 refs, 1 fig., 1 tab.

  6. Terrestrial Cosmogenic-Nuclide Dating of Alluvial Fans in Death Valley, California

    Science.gov (United States)

    Machette, Michael N.; Slate, Janet L.; Phillips, Fred M.

    2008-01-01

    We have used terrestrial cosmogenic nuclides (TCN) to establish the age of some of the most extensive Quaternary alluvial fans in Death Valley, California. These intermediate-age alluvial fans are most extensive on the western side of the valley, where tectonic deformation is considerably less pronounced than on the eastern side of the valley. These fans are characterized by a relatively smooth, densely packed desert pavement formed by well-varnished (blackened) clasts. These surfaces have been mapped as the Q2 gravel by previous workers and as unit Qai (intermediate age) by us. However, the intermediate-age gravels probably contain multiple subunits, as evidenced by slight differences in morphologic expression, soil formation, and inset geomorphic relations. The TCN technique used herein sums the cosmogenic 36Cl in approximately 2.5-meter-deep profiles through soil and host alluvium, thus avoiding some of the problems associated with the more typical surface-exposure dating of boulders or smaller clasts. Our TCN 36Cl dating of 12 depth profiles indicates that these intermediate-age (Qai) alluvial fans range from about 100 to 40 kilo-annum (ka), with a mean age of about 70 ka. An alternative interpretation is that alluvial unit Qai was deposited in two discrete episodes from 90 to 80 ka and from 60 to 50 ka, before and after MIS (marine oxygen-isotope stage) 4 (respectively). Without an intermediate-age unit, such as MIS 4 lake deposits, we can neither disprove nor prove that Qai was deposited in two discrete intervals or over a longer range of time. Thus, in Death Valley, alluvial unit Qai largely brackets MIS 4, which is not associated with a deep phase of Lake Manly. These Qai fans extend to elevations of about -46 meters (150 feet below sea level) and have not been transgressed by Lake Manly, suggesting that MIS 4 or MIS 2 lakes were rather shallow in Death Valley, perhaps because they lacked inflow from surface runoff of the Sierra Nevada drainages through

  7. Deglacial history of the Pensacola Mountains, Antarctica from glacial geomorphology and cosmogenic nuclide surface exposure dating

    Science.gov (United States)

    Bentley, M. J.; Hein, A. S.; Sugden, D. E.; Whitehouse, P. L.; Shanks, R.; Xu, S.; Freeman, S. P. H. T.

    2017-02-01

    The retreat history of the Antarctic Ice Sheet is important for understanding rapid deglaciation, as well as to constrain numerical ice sheet models and ice loading models required for glacial isostatic adjustment modelling. There is particular debate about the extent of grounded ice in the Weddell Sea embayment at the Last Glacial Maximum, and its subsequent deglacial history. Here we provide a new dataset of geomorphological observations and cosmogenic nuclide surface exposure ages of erratic samples that constrain the deglacial history of the Pensacola Mountains, adjacent to the present day Foundation Ice Stream and Academy Glacier in the southern Weddell Sea embayment. We show there is evidence of at least two glaciations, the first of which was relatively old and warm-based, and a more recent cold-based glaciation. During the most recent glaciation ice thickened by at least 450 m in the Williams Hills and at least 380 m on Mt Bragg. Progressive thinning from these sites was well underway by 10 ka BP and ice reached present levels by 2.5 ka BP, and is broadly similar to the relatively modest thinning histories in the southern Ellsworth Mountains. The thinning history is consistent with, but does not mandate, a Late Holocene retreat of the grounding line to a smaller-than-present configuration, as has been recently hypothesized based on ice sheet and glacial isostatic modelling. The data also show that clasts with complex exposure histories are pervasive and that clast recycling is highly site-dependent. These new data provide constraints on a reconstruction of the retreat history of the formerly-expanded Foundation Ice Stream, derived using a numerical flowband model.

  8. Precise determination of cosmogenic Ne in CREU-1 quartz standard, using the Helix-MC Plus mass spectrometer

    Science.gov (United States)

    Hamilton, D.; Honda, M.; Zhang, X.; Phillips, D.; Matchan, E.

    2017-12-01

    The Helix-MC Plus multi-collector noble gas mass spectrometer at the Australian National University is uniquely equipped with three high mass resolution collectors on H2, Axial and L2 positions. Their mass resolution and mass resolving power are as high as 1,800 and 8,000, respectively. The Helix-MC Plus can totally separate 20Ne+ from 40Ar++ isobaric interference and also partially separate 21Ne+ from 20NeH+ and 22Ne+ from 12C16O2++. By adjusting collector positions, we are able to measure interference-free Ne isotope intensities and have re-determined the 21Ne abundance in air [1]. Analyses by Honda et al. [1] demonstrated that 20Ne1H contributes approximately 2% to previously determined atmospheric 21Ne values [2], and a new atmospheric 21Ne/20Ne ratio of 0.002906 was calculated. Using the Helix-MC Plus mass spectrometer, we measured Ne abundances in the CREU-1 quartz standard [3] and determined cosmogenic concentrations by subtraction of atmospheric Ne with the new atmospheric 21Ne/20Ne value. The average concentration of cosmogenic 21Ne determined from four repeated analyses is 338 ± 12 × 106 atom/g (2σ). This compares with the average concentration of 348 ± 10 × 106 atom/g (2σ) from 45 analyses determined by several laboratories [3], where Ne isotope analyses were undertaken by conventional low resolution mass spectrometers and atmospheric Ne was subtracted using the conventional atmospheric 21Ne/20Ne [2]. On this basis, for a sample with abundant cosmogenic Ne, like CREU-1 quartz, previously measured by low mass resolution mass spectrometers are likely valid and their geological implications are unaffected. However, for low 21Ne concentration samples, combining new generation of mass spectrometers as well as the new atmospheric ratio may have significance for cosmogenic 21Ne surface exposure dating. References: [1] Honda M., et. al., International Journal of Mass Spectrometry, 387, 1 (2015). [2] Eberhardt P., et. al., Zeitschrift fur Naturforschung, 20

  9. Atmospheric radiocarbon calibration to 45,000 yr B.P.: late glacial fluctuations and cosmogenic isotope production

    Science.gov (United States)

    Kitagawa; van der Plicht J

    1998-02-20

    More than 250 carbon-14 accelerator mass spectrometry dates of terrestrial macrofossils from annually laminated sediments from Lake Suigetsu (Japan) provide a first atmospheric calibration for almost the total range of the radiocarbon method (45,000 years before the present). The results confirm the (recently revised) floating German pine chronology and are consistent with data from European and marine varved sediments, and combined uranium-thorium and carbon-14 dating of corals up to the Last Glacial Maximum. The data during the Glacial show large fluctuations in the atmospheric carbon-14 content, related to changes in global environment and in cosmogenic isotope production.

  10. Diffraction scattering of 7Be and 8B on 12C taking into account the coulomb interaction

    International Nuclear Information System (INIS)

    Davydovskyy, V.V.; Evlanov, M.V.; Tartakovsky, V.K.

    2004-01-01

    The differential cross sections for scattering of 7 Be and 8 B nuclei on 12 C nuclei are calculated in the framework of general theory of diffraction interactions of nuclei consisting of two charged weakly-bound clusters. Available experimental data are analyzed. (author)

  11. Radiative capture reaction {sup 7}Be(p,{gamma}){sup 8}B in the continuum shell model

    Energy Technology Data Exchange (ETDEWEB)

    Bennaceur, K; Ploszajczak, M [Grand Accelerateur National d` Ions Lourds (GANIL), Caen (France); Nowacki, F [Grand Accelerateur National d` Ions Lourds (GANIL), Caen (France); [Lab. de Physique Theorique Strasbourg, Strasbourg (France); Okolowicz, J [Grand Accelerateur National d` Ions Lourds (GANIL), Caen (France); [Inst. of Nuclear Physics, Krakow (Poland)

    1998-06-01

    We present here the first application of realistic shell model (SM) including coupling between many-particle (quasi-)bound states and the continuum of one-particle scattering states to the calculation of the total capture cross section and the astrophysical factor in the reaction {sup 7}Be(p,{gamma}){sup 8}B. (orig.)

  12. A new measurement of the proton capture rate on $^{7}$Be and the S$_{17}$(0) factor

    CERN Document Server

    Baby, L T; Goldring, G; Hass, M; Weissman, L; Fedosseev, V; Köster, U; Haquin, G; Gäggeler, H W; Weinreich, R

    2003-01-01

    The $^{7}$Be(p, $\\gamma$) $ \\,^{8}$B reaction plays a central role in the evaluation of solar neutrino fluxes. We report on a new precision measurement of the cross section of this reaction, following our previous experiment with an implanted target, a raster scanned beam and the elimination of back-scattering losses. The new measurement incorporates a higher activity $^{7}$Be target and a number of improvements in design and procedure. The cross section at Ec.m. = 850 keV was measured several times under varying experimental conditions, yielding a value of S$_{17}$(Ec.m.=850 keV) = 24.0 $\\pm$ 0.5 eV b. Measurements were carried out at lower energies as well. We obtain from the entire set of measurements an extrapolated value of S$_{17}$(0) = 21.2 $\\pm$ 0.7 eV b.

  13. Direct measurement of the 7Be(n, α4 He reaction cross sections for the cosmological Li problem

    Directory of Open Access Journals (Sweden)

    Kawabata Takahiro

    2017-01-01

    Full Text Available The cross sections of the 7Be(n, α4He reaction for p-wave neutrons were experimentally determined at Ec.m. = 0.20−0.81 MeV close to the Big Bang nucleosynthesis (BBN energy window for the first time on the basis of the detailed balance principle by measuring the time-reverse reaction. The obtained cross sections are much larger than the cross sections for s-wave neutrons inferred from the recent measurement at the n_TOF facility in CERN, but significantly smaller than the theoretical estimation widely used in the BBN calculations. The present results suggest the 7Be(n, α4 He reaction rate is not large enough to solve the cosmological lithium problem

  14. Evolution of the texture, mechanical properties, and microstructure of Cu-2.7Be alloys during hot cross-rolling

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Daibo; Liu, Chuming; Liu, Yadi; Gao, Yonghao; Jiang, Shunong [Central South University, School of Materials Science and Engineering, Changsha (China); Han, Tan [Suzhou Kinkou Copper Industry Limited Liability Company, Taicang (China)

    2015-09-15

    The evolution of the microstructure and texture of Cu-2.7Be alloys during hot rolling was investigated and related to the mechanical properties of the resulting sheets. Hot cross-rolling is shown to be an effective way to refine the hard and brittle secondary-phase particles in Cu-2.7Be alloys. The Cu- and brass-type textures increase and decrease in prevalence, respectively, during the rolling process. The yield strengths along the first and second rolling directions, and 45 to the former, are all enhanced because the corresponding Schmid factors decrease as the sheets are rolled thinner. The ductility anisotropy of the as-rolled sheets is related to the distribution and shape of the secondary-phase particles therein. (orig.)

  15. Precision measurement of the 7Be solar neutrino rate and absence of day-night asymmetry in Borexino

    International Nuclear Information System (INIS)

    Davini, S.

    2011-01-01

    Borexino, in data taking since May 2007, is the only experiment capable to perform the measurement of low-energy solar-ν. Borexino has performed the first direct measurement of the 7 Be solar-ν rate with accuracy better than 5%. The absence of day-night asymmetry of the 7 Be solar-ν rate was measured with a total uncertainty of 1%. Borexino results alone reject the Low Δm 2 (LOW) region of solar-ν oscillation parameters at more than 8.5 σ CL. Combined with the other solar-ν data, Borexino measurements isolate the Large Mixing Angle (LMA)- Mikheyev Smirnov Wolfenstein (MSW) solution of neutrino oscillations without assuming CPT invariance in the neutrino sector.

  16. Simultaneous measurement of angular distribution of elastic scattering for 6Li, 7Be, and 8B in 58Ni

    International Nuclear Information System (INIS)

    Ruiz S, A.; Martinez Q, E.; Aguilera R, E.F.; Murillo O, G.; Lizcano C, D.; Gomez C, A.

    2007-01-01

    The experimental angular distributions of elastic scattering for the projectiles 6 Li, 7 Be, 8 B in 58 Ni were obtained. Using the Optical model with a Woods-Saxon potential form, as much for the real part as for the imaginary one, an adjustment to the experimental data varying only the depth of the imaginary part of the potential is made. A comparison of the results obtained for each projectile is made. (Author)

  17. Preliminary study of 7Be, 137Cs and 131I activity concentration distribution rule in Beijing aerosol

    International Nuclear Information System (INIS)

    Fan Yuanqing; Wang Shilian; Zhang Xinjun; Li Qi; Jia Huaimao; Zhao Yungang; Chen Zhanying; Chang Yinzhong; Liu Shujiang; Li Huijuan

    2013-01-01

    The process of aerosol sampling and measuring of Beijing Radionuclide Station and Beijing Radionuclide Laboratory of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) International Monitoring System (IMS) was described. Long time aerosol monitoring data of the station and the laboratory were analyzed through statistic method and the characteristic and rule of the concentration distribution of nuclides 7 Be, 137 Cs and 131 I were obtained. The foundation was formed for further studying the rule of the radionuclide distribution in atmosphere. (authors)

  18. Reconstruction of 137Cs signal in cuba using 7be as a Tracer of vertical transport processes in the Atmosphere

    International Nuclear Information System (INIS)

    Alonso Hernandez, C.M.; Cartas Aguila, H.; Diaz Asencio, M.; Munnoz Caravaca, A.

    2001-01-01

    The goal of this study is to estimate the 137Cs signal in Cuba using the relation 137Cs/7Be for Miami and Cienfuegos City's obtained for four year and data base of 137Cs concentration in aerosols for Miami since 1957. The temporal behaviour of 137Cs and 7Be in aerosols in the Central and Southern region of Cuba are shown too. Sampling of aerosols was carried out in the Environmental Study Centre (22 grade 03'N, 80 grade 29'W) facilities during June/1994 - December/1998 in Cienfuegos Province. Aerosols were collected by an integral method using the facility Primus I, with 0.65 m2 collection area, 1200 m3h-1 air flux during 7 days collection time. Petrianov filter FPP-15-1.5 was used (efficiency collection of 99% to aerosols 0.3-1.5 mm diameter). After collection, the filters were ashed at 350 grade for 72 hours, put in appropriate geometry and analysed by gamma spectrometry. 137Cs mean concentration in aerosols was 1.09 mBqm-3 and the range of variations was 0.18-3.24 mBqm-3 ; while the 7Be was 4.10 mBqm-3 with 0.96-10.46 mBqm-3 variation range. These results allow to establish a relationship between 137Cs concentrations in aerosols from Cienfuegos and Miami in the same period, normalising in both cases with 7Be values; this normalisation allows to discriminate the variations due to local meteorological conditions and latitudinal position

  19. Preliminary study of the 19F(7Li,7Be)19O reaction at 52 MeV with MAGNEX

    CERN Document Server

    Cavallaro, M; Cappuzzello, F; Carbone, D; Foti, A; Orrigo, S E A; Rodrigues, M R D; Schillaci, M; Borello-Lewin, T; Petrascu, H

    2010-01-01

    The 19F(7Li,7Be)19O charge-exchange reaction at 52 MeV incident energy has been performed at INFN-LNS in Catania using the MAGNEX spectrometer. The use of an algebraic ray-reconstruction technique has allowed to extract the 19O excitation energy spectrum and the experimental angular distributions obtained with a single angular setting of the spectrometer.

  20. Accessing the application of in situ cosmogenic 14C to surface exposure dating of amorphous SiO2

    Science.gov (United States)

    Cesta, J. M.; Goehring, B. M.; Ward, D. J.

    2017-12-01

    We assess the feasibility and utility of in situ cosmogenic 14C as a geochronometer for landforms composed of amorphous SiO2 through the comparison of 14C surface exposure ages to independently determined eruption ages on Obsidian Dome, California. Landforms composed of amorphous SiO2 phases are difficult to date by conventional cosmogenic nuclide methods due to several complications that may arise (e.g., inability to remove meteoric contamination). The onset of an increased understanding of production rates and analytical measurement of in situ 14C in SiO2 provides an opportunity to address this limitation. Obsidian Dome is a 600-year-old phreatomagmatic dome of the Mono-Inyo Craters located in Inyo County, California, and consists of vesicular pumice, obsidian, and rhyolite. Exposure ages from eight obsidian and banded pumice and obsidian surface samples range from 3947 ± 678 to 914 ± 134 years, all significantly older than the accepted radiocarbon age of 650-550 years. δ13C values for the samples range between +2.65‰ and +1.34‰ and show a negative correlation with CO2 yield. The `too old' exposure ages coupled with this negative correlation between δ13C and CO2 yield suggests the incorporation of an atmospheric component of 14C. Measurement of 14C concentrations in shielded, subsurface samples will assist in isolating the atmospheric 14C component and aid in correcting the surface exposure ages.

  1. Constraining Quaternary ice covers and erosion rates using cosmogenic 26Al/10Be nuclide concentrations

    Science.gov (United States)

    Knudsen, Mads Faurschou; Egholm, David Lundbek

    2018-02-01

    Paired cosmogenic nuclides are often used to constrain the exposure/burial history of landforms repeatedly covered by ice during the Quaternary, including tors, high-elevation surfaces, and steep alpine summits in the circum-Arctic regions. The approach generally exploits the different production rates and half-lives of 10Be and 26Al to infer past exposure/burial histories. However, the two-stage minimum-limiting exposure and burial model regularly used to interpret the nuclides ignores the effect of variable erosion rates, which potentially may bias the interpretation. In this study, we use a Monte Carlo model approach to investigate systematically how the exposure/burial and erosion history, including variable erosion and the timing of erosion events, influence concentrations of 10Be and 26Al. The results show that low 26Al/10Be ratios are not uniquely associated with prolonged burial under ice, but may as well reflect ice covers that were limited to the coldest part of the late Pleistocene combined with recent exhumation of the sample, e.g. due to glacial plucking during the last glacial period. As an example, we simulate published 26Al/10Be data from Svalbard and show that it is possible that the steep alpine summits experienced ice-free conditions during large parts of the late Pleistocene and varying amounts of glacial erosion. This scenario, which contrasts with the original interpretation of more-or-less continuous burial under non-erosive ice over the last ∼1 Myr, thus challenge the conventional interpretation of such data. On the other hand, high 26Al/10Be ratios do not necessarily reflect limited burial under ice, which is the common interpretation of high ratios. In fact, high 26Al/10Be ratios may also reflect extensive burial under ice, combined with a change from burial under erosive ice, which brought the sample close to the surface, to burial under non-erosive ice at some point during the mid-Pleistocene. Importantly, by allowing for variable

  2. Technological advances in cosmogenic neutron detectors for measuring soil water content

    Science.gov (United States)

    Zreda, M. G.; Schrön, M.; Köhli, M.

    2017-12-01

    The cosmic-ray neutron probe is used for measuring area-average soil water content at the hectometer scale. Early work showed a simple exponential decrease with distance of the instrument's sensitivity and a footprint 300 m in radius. Recent research suggested a much higher sensitivity to local neutrons and reduced footprint. We show results confirming the high sensitivity to local neutrons, describe two ways to reduce local and increase far-field effects, and propose ways of measuring neutrons at different spatial scales. Measurements with moderated detectors across a 10-m-wide creek and a 2-m-wide water tank show a decrease by 30% and 20%, respectively, of neutron intensity over water compared to that over land nearby. These results mean that the detector is sensitive to meter-scale heterogeneities of water content. This sensitivity can be reduced by rising the detector or by shielding it from local neutrons. The effect of local water distributions on the measured neutron intensity decreases with height. In the water tank experiment it disappeared almost completely at the height of 2 m, leading to the conjecture that the height roughly equal to the horizontal scale of heterogeneity would eliminate the sensitivity. This may or may not be practical. Shielding the detector below by a hydrogenous material removes a substantial fraction of the local neutrons. The shielded detector has a reduced count rate, reduced sensitivity to local neutrons and increased sensitivity to neutrons farther afield, and a larger footprint. Such a detector could be preferable to the current cosmogenic-neutron probe under heterogeneous soil water conditions. The shielding experiments also inspired the development of a local-area neutron detector. It has hydrogenous neutron shields on all sides except the bottom, substantially blocking the neutrons coming from afar, while allowing the neutrons coming directly from below. Its footprint is equal to its physical dimension when the detector is

  3. Cosmogenic 10Be signature of geomagnetic dipole moment variations over the last 2 Ma

    Science.gov (United States)

    Simon, Q.; Thouveny, N.; Bourlès, D. L.; Valet, J. P.; Bassinot, F. C.; Savranskaia, T.; Duvivier, A.; Choy, S.; Gacem, L.; Villedieu, A.

    2017-12-01

    Long-term variations of the geomagnetic dipole moment (GDM) during periods of stable polarity and in transitional states (reversals and excursions) provide key information for understanding the geodynamo regime. Authigenic 10Be/9Be ratios (Be-ratio, proxy of atmospheric 10Be production) from marine sedimentary cores give independent and additional insights on the evolution of the geomagnetic intensity, completing information from absolute and relative paleointensity (RPI) records. Here we present new Be-ratio results obtained on several marine cores from the North Atlantic, Indian and Pacific Oceans which permit to extent into the Matuyama chron our previous 10Be-derived GDM reconstructions (Simon et al., 2016 JGR 121). Stratigraphic offsets measured between Be-ratio peaks and the corresponding RPI minima in each studied cores are assigned to (post-) detrital remanent magnetization (pDRM) effects leading to magnetization locking-in delays varying from 0 to 16 cm (up to 12 ka). All these results were compiled in order to obtain a continuous Be-ratio record covering the last 2 Ma. 10Be overproduction episodes triggered by geomagnetic dipole moment lows (GDL) linked to polarity reversals and excursions confirm the global control exerted by the GDM on cosmogenic radionuclides production. A dipole moment reconstruction derived from the Be-ratio stack (BeDiMo2Ma) was calibrated using absolute paleointensity data. This independent record completes the available paleomagnetic RPI records and permits: 1) to confront and increase the robustness and precision of GDM reconstructions; and, 2) to better constrain geomagnetic field instabilities during the mid- to late- Matuyama chron. Our new 10Be derived inventory is fully compatible with the GDL series linked to polarity reversals (Matuyama-Brunhes transition, Jaramillo and Olduvai boundaries), geomagnetic events (Cobb Mountain, Réunion) and Brunhes' excursions (e.g. Laschamp, Blake, Iceland-Basin, Big Lost). It further

  4. Cosmogenic Nuclide Exposure Dating of the Tiltill Rock Avalanche, Yosemite National Park

    Science.gov (United States)

    Ford, K. R.; Pluhar, C. J.; Stone, J. O.; Stock, G. M.; Zimmerman, S. R.

    2013-12-01

    Yosemite National Park serves as an excellent natural laboratory for studying rock falls and rock avalanches because these are the main processes modifying the nearly vertical slopes of this recently glaciated landscape. Mass wasting represents a significant hazard in the region and the database of previous rock falls and other mass wasting events in Yosemite is extensive, dating back to the mid-1800s. However, this record is too short to capture the recurrence characteristics and triggering mechanisms of the very largest events, necessitating studies of the geologic record of mass wasting. Rock falls and rock avalanches are readily dated by cosmogenic nuclide methods due to their instantaneous formation, and results can be tied to triggering events such as seismic activity (e.g. Stock et al., 2009). Here, we apply exposure dating to the Holocene Tiltill rock avalanche north of Hetch Hetchy Reservoir. The deposit comprises what appear to be two separate lobes of rock and debris, yielding a total volume of ~3.1 x 106 m3. Assuming an erosion rate of 0.0006 cm/yr and neglecting snowpack shielding, preliminary data suggest a mean exposure age of 11,000 + 600 year B.P. for both deposits, indicating that they were emplaced in a single event. The age of the Tiltill 'slide' is similar to earthquakes on the Owens Valley Fault between 10,800 + 600 and 10,200 + 200 cal year B.P. (Bacon, 2007) and the White Mountain Fault, ~10,000 cal year B.P. (Reheis, 1996; DePolo, 1989). Given that movement on the Owens Valley fault in 1872 caused a number of rock falls in Yosemite and the coincidence of ages between the Tiltill 'slide' and paleoseismic events, a large earthquake in Eastern Sierra Nevada may have triggered this event. Other trigger events are also possibilities, but only through compilation of a database of large rock avalanches can statistically significant groupings of events begin to demonstrate whether seismic triggering is a dominant process.

  5. Activity size distributions of some naturally occurring radionuclides 7Be, 40K and 212Pb in indoor and outdoor environments

    International Nuclear Information System (INIS)

    Mohamed, A.

    2005-01-01

    The activity size distributions of natural radionuclides 7 Be and 40 K were measured outdoor in El-Minia city, Egypt by means of gamma spectroscopy. A low-pressure Berner cascade impactor was used as a sampling device. The activity size distribution of both 7 Be and 40 K was described by one log-normal distribution, which was represented by the accumulation mode. The activity median aerodynamic diameter (AMAD) of 7 Be and 40 K was determined to be 530 and 1550nm with a relative geometric standard deviation (δ, which was defined as the dispersion of the peak) of 2.4 and 2, respectively. The same sampling device (Berner impactor) and a screen diffusion battery were used to measure the activity size distribution, activity concentration and unattached fraction (f P ) of 212 Pb in indoor air of El-Minia City, Egypt. The mean activity median aerodynamic diameter (AMAD) of the accumulation mode for attached 212 Pb was determined to be 250nm with a mean geometric standard deviation (δ) of 2.6. The mean value of the specific concentration of 212 Pb associated with that mode was determined to be 460+/-20mBqm -3 . The activity median thermodynamic diameter (AMTD) of unattached 212 Pb was determined to be 1.25nm with δ of 1.4. A mean unattached fraction (f p ) of 0.13+/-0.02 was obtained at a mean aerosol particle concentration of 1.8x10 3 cm -3 . The mean activity concentration of unattached 212 Pb was found to be 19+/-3mBqm -3 . It was found that the aerosol concentration played an important role in varying the unattached, attached activity concentration and unattached fraction (f P )

  6. River-plume sedimentation and 210Pb/7Be seabed delivery on the Mississippi River delta front

    Science.gov (United States)

    Keller, Gregory; Bentley, Samuel J.; Georgiou, Ioannis Y.; Maloney, Jillian; Miner, Michael D.; Xu, Kehui

    2017-06-01

    To constrain the timing and processes of sediment delivery and submarine mass-wasting events spanning the last few decades on the Mississippi River delta front, multi-cores and gravity cores (0.5 and water depth in 2014. The cores were analyzed for radionuclide activity (7Be, 210Pb, 137Cs), grain size, bulk density, and fabric (X-radiography). Core sediments are faintly bedded, sparsely bioturbated, and composed mostly of clay and fine silt. Short-term sedimentation rates (from 7Be) are 0.25-1.5 mm/day during river flooding, while longer-term accumulation rates (from 210Pb) are 1.3-7.9 cm/year. In most cores, 210Pb activity displays undulatory profiles with overall declining activity versus depth. Undulations are not associated with grain size variations, and are interpreted to represent variations in oceanic 210Pb scavenging by river-plume sediments. The 210Pb profile of one gravity core from a mudflow gully displays uniform basal excess activity over a zone of low and uniform bulk density, interpreted to be a mass-failure event that occurred 9-18 years before core collection. Spatial trends in sediment deposition (from 7Be) and accumulation (from 210Pb) indicate that proximity to the river mouth has stronger influence than local facies (mudflow gully, depositional lobe, prodelta) over the timeframe and seabed depth represented by the cores (sediment deposition from river plumes coupled with infrequent tropical cyclone activity near the delta in the last 7 years (2006-2013), and by the location of most sediment failure surfaces (from mass flows indicated by parallel geophysical studies) deeper than the core-sampling depths of the present study.

  7. Angular measurement of the energy distribution of neutrons from the thick target 7Li(p,n)7Be source

    International Nuclear Information System (INIS)

    Rose, A.

    1981-11-01

    The energy spectrum of neutrons emitted from a thick lithium target bombarded by protons has been measured as a function of neutron angle of emission. The measurements were done at proton energies up to 2.8 MeV and at 30 deg. intervals in the range 0 to 120 deg. using proportional detectors with gas fillings of hydrogen and methane. A review is given of papers published on the 7 Li(p,n) 7 Be reactions at 0 deg.; where applicable, comparisons are made with the present results

  8. Contribution to the study of excited levels of 7Be obtained from the reaction 6Li (p, α)

    International Nuclear Information System (INIS)

    Beaumevieille, H.

    1964-05-01

    The interpretation of the results of the reaction 6 Li (p, α) in the energy range 100 keV to 3 MeV has been done with the next levels of 7 Be : 3/2- (5,9 MeV), 3/2+ (6,2 MeV), 5/2- (7,18 MeV) and a level the characteristics of which may be 1/2+ or 4 P (9,5 MeV). (author) [fr

  9. Rate of bedrock channel incision by waterfall retreat and landscape response constrained by cosmogenic 3He, Kauai, Hawaii

    Science.gov (United States)

    Mackey, B. H.; Lamb, M. P.; Scheingross, J. S.; Farley, K. A.

    2011-12-01

    Channel incision and knickpoint retreat are the drivers of landscape evolution, yet we are still challenged to quantify the rate and processes by which rivers cut into rock. The Napali Coast on the northwestern side of Kauai, Hawaii, has multiple linear channels incising >200 m into the shield volcano surface. The channels have well-constrained initial conditions, including original topography, and relatively uniform layered basalt of known age (~4.5 Ma), which have attracted previous studies of channel evolution (e.g., Seidl et al., 1994, 1997). Many channels feature prominent waterfalls, although the mechanism of knickpoint initiation (submarine landslide vs cliff erosion) and subsequent retreat remain ambiguous. Motivated by these knowledge gaps and recent advances in cosmogenic helium geochronology, we revisited the Kaulaula Valley, a 9 km long narrow valley, beheaded on its upslope extent by the Waimea Canyon, and ending near the coast at the northern Mana Plain. Four kilometers up the canyon is a prominent 40 m high vertical knickpoint, dividing the valley into strongly contrasting geomorphic domains. The boulder-lined channel below the knickpoint is linear, steep (15%), and confined to a narrow valley with steep rocky cliffs (average slope 31°). Large, >2 m diameter angular boulders in the lower section of channel show evidence of mobility from debris flows. Above the knickpoint, average channel gradient is reduced (9%), bed load is much finer, and convex, soil-mantled hillslopes have a consistently lower mean slope of 18°. We constrained the exposure age of 18 features (in-channel boulders, stable boulders on terraces, and in-channel bedrock) along the length of the channel, by analysis of cosmogenic 3He in olivine phenocrysts. Cosmogenic exposure ages are oldest near the coast (80 ka) and systematically decrease with upstream distance towards the waterfall (model of knickpoint retreat and downstream terrace abandonment advocated by Seidl (1997), and we

  10. Timing of Expansions of the Quelccaya Ice Cap, Peru, and Implications for Cosmogenic Nuclide Production Rate Calibration

    Science.gov (United States)

    Lowell, T. V.; Kelly, M. A.; Applegate, P. J.; Smith, C. A.; Phillips, F. M.; Hudson, A. M.

    2010-12-01

    We calibrate the production rate of the cosmogenic nuclide beryllium-10 (10Be) at a low-latitude, high-elevation site, using nuclide concentrations measured in moraine boulders and an independent chronology determined with bracketing radiocarbon dates. The measurement of terrestrial cosmogenic nuclide (TCN) concentrations in earth surface materials has been an important development for understanding a host of earth surface processes. Uncertainty in cosmogenic nuclide production rates has hampered application of this method. Here, we contribute to the estimation of 10Be production rates by reporting both preliminary 10Be concentrations and independent radiocarbon dates from a low latitude, high elevation site. Our study site in the southeastern Peruvian Andes (~13.9°S, 70.9°W, 4850 m asl) is centered on a moraine set, known as the Huancané II moraines, that represents a ~4 km expansion of Quelccaya Ice Cap during late glacial time. At this location, organic material situated both stratigraphically below and above moraines in two adjacent valleys provide material for radiocarbon dating. Based on geomorphic arguments, we correlate results from the two valleys. The timing of ice cap margin advance is bracketed by 13 radiocarbon ages on organic material within the outermost Huancané II moraines that range from 13.6 to 12.5 ka. Two stratigraphic sections upvalley from the moraines yield 6 radiocarbon ages from 11.3 to 12.4 ka, indicating the time of retreat . We computed the probability density function that lies between these two sets of dates, and assign an age of 12.4 ka (+/-???) for the formation of the Huancané II moraines. Calculating beryllium-10 exposure dates from the measured concentrations yield exposure dates that significantly underestimate the independently determined age of the moraine (~8-30%), if existing production rate estimates are used. We suggest that the radiocarbon age for the moraines can be used as a robust independent calibration for 10Be

  11. Tectonic-Volcanic Interplay in the Dabbahu Segment of the Afar Rift from Cosmogenic 3He Constraints

    Science.gov (United States)

    Williams, A.; Pik, R.; Burnard, P.; Lahitte, P.; Yirgu, G.; Adem, M.

    2008-12-01

    The Afar Rift in Ethiopia is one of the only subaerial locations in the world where the transition from continental break-up to oceanic-spreading can be observed. Extension and volcanism in the Afar is concentrated in tectono-magmatic segments (TMS), similar in size and morphology to those that characterise spreading ridges. The Dabbahu TMS is the southernmost of the western Afar and has recently been the site of significant activity. A massive seismic event in late 2005, triggered by the injection of an 8-m wide dyke, heralded the onset of a new rifting period in the Dabbahu TMS. Volcanic activity associated with the periods of magma-driven extension, which have recurred at 4-8 mth intervals, has been both silicic (explosive) and basaltic (fissural). The most recent activity in the Afar thus testifies to the close interplay of tectonics and magmatism in rifting environments. In an effort to decipher the long-term structural and volcanic evolution of Dabbahu TMS we have employed the cosmogenic nuclide dating technique to provide chronological data for the segment. This method has advantages over other geochronological tools in that we can target both volcanic and tectonic surfaces of a few Kyr to several Myr age. Baddi Volcano, located off-axis on the western margin of the TMS, is a bimodal central stratovolcano typical of the Afar TMS. Late-stage basaltic lava flows cap an acidic base, which has been dated at 290 ± 4 ka using the K-Ar technique (Lahitte et al., 2003). Following preliminary sampling in 2007, we have determined a cosmogenic 3He age of 53.4 ± 3.7 ka from multiple samples from one of the basaltic flows on the NW flank of Baddi. These data show a significant time gap (240 Kyr) between the final phase of acidic volcanism and the onset of basaltic activity at the central volcanoes, presumably related to the rate of magma chamber replenishment. To test whether the spectacular shift to basaltic activity at 53 ka represents replenishment of the entire sub

  12. Surface Uplift Rate Constrained by Multiple Terrestrial Cosmogenic Nuclides: Theory and Application from the Central Andean Plateau

    Science.gov (United States)

    McPhillips, D. F.; Hoke, G. D.; Niedermann, S.; Wittmann, H.

    2015-12-01

    There is widespread interest in quantifying the growth and decay of topography. However, prominent methods for quantitative determinations of paleoelevation rely on assumptions that are often difficult to test. For example, stable isotope paleoaltimetry relies on the knowledge of past lapse rates and moisture sources. Here, we demonstrate how cosmogenic 10Be - 21Ne and/or 10Be - 26Al sample pairs can be applied to provide independent estimates of surface uplift rate using both published data and new data from the Atacama Desert. Our approach requires a priori knowledge of the maximum age of exposure of the sampled surface. Ignimbrite surfaces provide practical sampling targets. When erosion is very slow (roughly, ≤1 m/Ma), it is often possible to constrain paleo surface uplift rate with precision comparable to that of stable isotopic methods (approximately ±50%). The likelihood of a successful measurement is increased by taking n samples from a landscape surface and solving for one regional paleo surface uplift rate and n local erosion rates. In northern Chile, we solve for surface uplift and erosion rates using three sample groups from the literature (Kober et al., 2007). In the two lower elevation groups, we calculate surface uplift rates of 110 (+60/-12) m/Myr and 160 (+120/-6) m/Myr and estimate uncertainties with a bootstrap approach. The rates agree with independent estimates derived from stream profile analyses nearby (Hoke et al., 2007). Our calculated uplift rates correspond to total uplift of 1200 and 850 m, respectively, when integrated over appropriate timescales. Erosion rates were too high to reliably calculate the uplift rate in the third, high elevation group. New cosmogenic nuclide analyses from the Atacama Desert are in progress, and preliminary results are encouraging. In particular, a replicate sample in the vicinity of the first Kober et al. (2007) group independently yields a surface uplift rate of 110 m/Myr. Compared to stable isotope

  13. Reaction cross sections and elastic scattering energy dependence around the Coulomb barrier for the {sup 7}Be+{sup 27}Al system

    Energy Technology Data Exchange (ETDEWEB)

    Morcelle, Viviane; Gomes, P.R.S.; Lubian, J.; Mendes Junior, D.R. [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil); Lichtenthaeler, R.; Guimaraes, V.; Lepine-Szily, A.; Camargo, O.; Faria, P.N. de; Gasquez, L.; Morais, M.C.; Condori, R.P.; Pires, K.C.C.; Scarduelli, V. [Universidade de Sao Paulo (USP), SP (Brazil); Barioni, A. [Universidade Federal da Bahia (UFBA), Salvador, BA (Brazil); Shorto, J.M.B. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Zamora, J.C. [Technische Universitaet Darmstadt (Germany); Aguilera, E.; Martinez-Quiroz, E. [Instituto Nacional de Investigaciones Nucleares (Mexico); Kolata, J.; Jiang, H. [University of Notre Dame, IN (United States); Bechetti, F.D.; Lamm, L.O. [Michigan University, MI (United States); Lizcano, D. [Universidad Autonoma del Estado de Mexico (Mexico)

    2012-07-01

    Full text: Elastic scattering measurements were performed at energies around the Coulomb barrier at the Tandem Accelerators of the Sao Paulo (USP - Brazil ) and Notre Dame (UND - USA) Universities. The {sup 7}Be is a radioactive nucleus and has been produced by the reaction {sup 6}He({sup 6}Li,{sup 9}Be) and impinged on {sup 27}Al and {sup 197}Au secondary targets using a double superconducting systems RIBRAS ( USP ) and Twinsol (UND). The elastic scattering angular distributions were analyzed through the optical model calculations, using the Woods- Saxon form factors [1] and the Sao Paulo potential [2] to fit the experimental data. The total reaction cross sections were also derived and compared with others presented at the literature for other systems. In addition, a study of the nuclear potential energy dependence has been carried out in this work in the dispersion relation context. Due to the fact that {sup 7}Be has a small breakup threshold energy, the results can provide significant information of the influence of the breakup channel on the reactions involving this projectile. For this purpose, {chi}{sup 2}- data analysis with different kind of potentials were performed to identify the energy dependence of the real (V) and imaginary (W) parts of the potential. [1] L.C. Chamon et al., Phys. Rev. C 66, (2002) 014610. [2] R.D. Wood e D.S. Saxon, Phys. Rev. 95 ( 1954) 577. (author)

  14. New method to evaluate the {sup 7}Li(p, n){sup 7}Be reaction near threshold

    Energy Technology Data Exchange (ETDEWEB)

    Herrera, María S., E-mail: herrera@tandar.cnea.gov.ar [Comisión Nacional de Energía Atómica, Av. Gral. Paz 1499, Buenos Aires B1650KNA (Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas, Av. Rivadavia 1917, Ciudad Autónoma de Buenos Aires C1033AAJ (Argentina); Escuela de Ciencia y Tecnología, UNSAM, 25 de Mayo y Francia, Buenos Aires B1650KNA (Argentina); Moreno, Gustavo A. [YPF Tecnología, Baradero S/N, Buenos Aires 1925 (Argentina); Departamento de Física J. J. Giambiagi, Facultad de Ciencias Exactas y Naturales, UBA, Ciudad Universitaria, Ciudad Autónoma de Buenos Aires 1428 (Argentina); Kreiner, Andrés J. [Comisión Nacional de Energía Atómica, Av. Gral. Paz 1499, Buenos Aires B1650KNA (Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas, Av. Rivadavia 1917, Ciudad Autónoma de Buenos Aires C1033AAJ (Argentina); Escuela de Ciencia y Tecnología, UNSAM, 25 de Mayo y Francia, Buenos Aires B1650KNA (Argentina)

    2015-04-15

    In this work a complete description of the {sup 7}Li(p, n){sup 7}Be reaction near threshold is given using center-of-mass and relative coordinates. It is shown that this standard approach, not used before in this context, leads to a simple mathematical representation which gives easy access to all relevant quantities in the reaction and allows a precise numerical implementation. It also allows in a simple way to include proton beam-energy spread affects. The method, implemented as a C++ code, was validated both with numerical and experimental data finding a good agreement. This tool is also used here to analyze scattered published measurements such as (p, n) cross sections, differential and total neutron yields for thick targets. Using these data we derive a consistent set of parameters to evaluate neutron production near threshold. Sensitivity of the results to data uncertainty and the possibility of incorporating new measurements are also discussed.

  15. Effects of Changing Hot Rolling Direction on Microstructure, Texture and Mechanical Properties of Cu-2.7Be Sheets

    Science.gov (United States)

    Zhu, Daibo; Liu, Chuming; Yu, Haijun; Han, Tan

    2018-03-01

    A hot rolling scheme (cross-rolling and unidirectional rolling) was adopted to process Cu-2.7Be sheets used as multiplier dynodes in photomultiplier. The effects of changing rolling direction on microstructure, texture and mechanical properties were studied by a combination of XRD, EBSD and TEM. It was found that higher copper-type texture and lower brass texture intensity were obtained in the ultimately cross-rolling (CR) sheet compared with the unidirectional rolling (UR) sheet.The EBSD results indicated that the grain orientation from mainly for UR sample turns to random for CR sample. Great enhancements in YS and UTS after unidirectional rolling were attributed to the massive and polygonal γ precipitates. The CR sample exhibited lower anisotropy, because of the increase of S and γ precipitates with spherical and tiny shape.

  16. In-situ cosmogenic 10Be and 36Cl studies in the earth sciences at the ANTARES AMS facility

    International Nuclear Information System (INIS)

    Fink, D.; Elliott, G.; Child, D.; Misfud, C.

    1998-01-01

    In parallel with a successful 14 C AMS program, routine measurements of 10 Be (T 1/2 = 1.5 Ma), 26 Al (0.7Ma) and 36 Cl (0.3Ma) have been demonstrated at the ANTARES AMS facility. With this capability, ANSTO is coordinating and funding a comprehensive program in the application of in-situ cosmogenic radioisotopes for Southern Hemisphere Quaternary climate change. The sub-projects within the program are based on strong university collaboration in the Earth Sciences and with the Australian Antarctic Division. A fully equipped geochemistry laboratory for chemically processing rock samples for AMS studies has been completed and is fully operational. In addition a variety of analytical techniques such as NAA, ICP-MS, XRF, XRD, etc are available through the Environment Division at ANSTO. A brief description of the research projects in glacial chronology and those related to landscape geomorphology is given

  17. Natural climate variability inferred from cosmogenic isotopes and other geophysical data and its impact on human activity

    International Nuclear Information System (INIS)

    Creer, K.M.

    2001-01-01

    The way how natural climate changes may have influenced anthropological development is discussed. The main characteristics of solar variability are reviewed: (1) as measured in detail over recent decades by instruments on-board artificial satellites; (2) as recorded in historical documents on the time-scale of centuries; and (3) as inferred on millennial time-scales from archived records of the cosmogenically generated isotopes 14 C and 10 Be. The older, proxy data comprise temperature changes reconstructed from tree ring studies and environmental changes deduced from multi-disciplinary studies of lake sediments. The effects of changes in ocean circulation and the sporadic influence of volcanic activity are also considered briefly. (author)

  18. Determination of primordial and cosmogenic radioactivity in achondritic meteorites by low-level, gamma-ray spectrometry

    International Nuclear Information System (INIS)

    Muntean, R.A.

    1979-08-01

    A high-sensitivity, low-background gamma-ray spectrometer containing two 23 cm by 13 cm thallium-activated, sodium iodide detectors was used to measure long-lived primordial and cosmogenic radioactivity in a suite of achondritic meteorites. Potassium, thorium, uranium, and 26 Al abundances were established for sixteen brecciated eucrites, two unbrecciated eucrites, a nakhlite, a chassignite, and a unique meteorite from Antarctica by nondestructive counting techniques. In several cases, multiple samples of the same meteorite fall were examined. Concentrations ranged from 79.8 ppM to 1150 ppM for potassium, 55.6 ppb to 663 ppb for thorium, 18.1 ppb to 190 ppb for uranium, and 45.0 dpm/kg to 99.0 dpm/kg for 26 Al. In addition, a 137 Cs concentration of 264 dpm/kg was observed in the Allan Hills 77005,9 specimen

  19. Cosmogenic Radionuclides in Antarctic Meteorites: Preliminary Results on Terrestrial Ages and Temporal Phenomena

    Science.gov (United States)

    Michlovich, E.; Vogt, S.; Wolf, S. F.; Elmore, D.; Lipschutz, M. E.

    1993-07-01

    Since 1969, more than 15,000 meteorites have been recovered from various sites in Antarctica. Differences have been reported between the Antarctic populations and the population of non-Antarctic meteorites in volatile trace- element content, thermoluminescence properties, physical size, and relative distribution of meteorite type [1]. Lipschutz and Samuels [2] developed a method based upon multivariate linear and logistic regression that they applied to interpret trace-element content in Antarctic and non-Antarctic meteorites, showing that the two populations can be chemically distinguished. Since Antarctic meteorites have, on the whole, much longer terrestrial ages than non-Antarctic falls, such differences have been used to support the notion that the flux of meteorites sampled by the Earth has changed in the recent past. A subsequent study [3] showed a statistically significant difference in trace-element content between meteorites from Victoria Land and those found in Queen Maud Land, two groups that seem to have different terrestrial age distributions. Changes in meteorite flux patterns on the order of 60 yr are indicated from a study of Cluster 1 vs. non-Cluster 1 falls [4]. Rapid fluctuations would almost certainly require the existence of co-orbital meteoroid streams, an idea that has been criticized by some [5] on dynamical grounds. To quantify the discussion of a temporal dependence of meteorite flux patterns, and to continue systematic study of Antarctic meteorites, we have measured the contents of the cosmogenic radionuclides ^10Be and ^26Al in the bulk phase, and ^36Cl in the metal phase, of 40 Antarctic specimens that are from the same suite of samples analyzed in the trace-element studies and that were chosen to minimize any chances of paired meteorites. The means and standard deviations of ^10Be and ^26Al activities are 16.4 +/- 3.5 and 48 +/- 8 dpm/kg respectively. Correction for cosmic ray exposure [6,7] and terrestrial ages allows us to estimate

  20. Radiogenic 3He/4He Estimates and Their Effect on Calculating Plio-Pleistocene Cosmogenic 3He Ages of Alluvial-Fan Terraces in the Lower Colorado River Basin, USA

    Science.gov (United States)

    Fenton, C.; Pelletier, J.

    2005-12-01

    Several alluvial-fan terraces near Topock, AZ were created by successive entrenchment of Pliocene and Pleistocene alluvial-fan gravels shed from the adjacent Black Mountains along the lower Colorado River corridor below Hoover Dam. These fans interfinger with and overlie main-stem Colorado River sands and gravels and grade to terrace levels that correspond with pre-existing elevations of the Colorado River. Absolute dates for the ages of Quaternary deposits on the lower Colorado River are rare and cosmogenic 3He age estimates of these surfaces would help constrain the timing of aggradation and incision in the lower Colorado River corridor. We analyzed individual basalt boulders from several terrace surfaces for total 3He/4He concentrations to calculate cosmogenic 3He ages of each fan terrace; 3He/4He values, expressed as R/Ra where Ra is the 3He/4He of air, range from 0.29 to 590. Black Mountain volcanic rocks have reported K-Ar ages between 15 and 30 Ma and basalt samples from adjacent alluvial fans contain 0.42 to 47× 1012 at/g of 4He, which has likely accumulated due to nuclear processes. The amount of radiogenic 3He/4He can be significant in old rocks with young exposure ages and can complicate determination of cosmogenic 3 He content. Alpha-decay of U, Th, and their daughter isotopes produces large amounts of 4He, whereas significant amounts of radiogenic 3He are only produced through the neutron bombardment of Li and subsequent beta-decay of tritium. We measured Li, U, Th, major and rare-earth element concentrations in whole-rock basalts and mineral separates. These concentrations are used to estimate the ratio of radiogenic helium contributed to the total helium system in our samples. Li concentrations typically range from 6 to 17 ppm, with one outlier of 62 ppm. U contents range from calculations predict that the average radiogenic helium (R/Ra) contributed to the total helium in Black Mountain basalt samples is 0.011. Other noble gas studies have shown

  1. Surface Exposure Geochronology Using Cosmogenic Nuclides: Applications in Antarctic Glacial Geology

    Science.gov (United States)

    1994-02-01

    in rocks, are particularly promising for directly dating 1 geological surfaces . In 1934, Grosse et al. first suggested that cosmic rays produce rare...and muons produced by cosmic ray irteractions in the atmosphere and in rocks, and spallation by I neutrons produced in muon capture reactions (Kurz...stable isotopes are useful for surface 3 exposure studies because they can act as integrators of cosmic ray exposure on long time scales, potentially up

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

    Science.gov (United States)

    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

  3. One Isotope, Two Tales: using plant and cosmogenic 14C to constrain Holocene glacier activity on Baffin Island.

    Science.gov (United States)

    Pendleton, S.; Miller, G. H.; Lifton, N. A.; Young, N. E.

    2017-12-01

    As the cryosphere continues to undergo rapid and accelerating change, it is more important than ever to understand past glacier activity to predict the future of the cryosphere. However, continuous Holocene glacier records are notoriously difficult to reconstruct because an advancing glacier will re-incorporate previous deposits so that moraines typically only record the farthest downvalley glacier expansion. Here we combine dates of ice margin advance from in situ dead vegetation with in situ cosmogenic 14C (in situ 14C) from preserved bedrock surfaces at the same locations to further constrain the timing of ice-free episodes during the Holocene following deglaciation on southern Baffin Island. Radiocarbon ages from recently exposed in situ plants suggest that ice last advanced over sample locations at 9.4, 9.2, 9.0, and 3.7 ka and that they remained ice covered until modern times. Associated in situ 14C inventories are variable, but well above background levels, suggesting some amount of Holocene in situ 14C production. Using plant 14C ages representing the beginning of ice coverage and in situ 14C inventories representative of exposure prior to ice coverage, a simple model of cosmogenic in situ 14C production (accounting for muon production through ice) provides constraints timing and duration of ice-free times at sample locations prior to their most recent burial. Using conservative Holocene ice thicknesses, the locations buried at 9.4, 9.2, and 9.0 ka require, at minimum, 1000 years of pre-burial exposure to match the observed in situ 14C inventory. This suggests these locations were ice free by at least 10 ka and likely earlier. The in situ 14C inventory at the location buried at 3.7 ka limits prior exposure to 2000 years, suggesting that this location experienced more complex Holocene ice cover/burial history. These pilot data show that valuable information regarding periods of exposure is contained within in situ 14C inventories. Additional paired plant and

  4. No surface breaking on the Ecemiş Fault, central Turkey, since Late Pleistocene (~ 64.5 ka); new geomorphic and geochronologic data from cosmogenic dating of offset alluvial fans

    Science.gov (United States)

    Sarıkaya, M. A.; Yıldırım, C.; Çiner, A.

    2015-05-01

    The Ecemiş Fault Zone (EF) has been recognized as a major left lateral strike-slip fault in the Central Anatolian Fault Zone (CAFZ) of Turkey. However, its Quaternary slip-rate has been challenging to determine due to the difficulty of dating offset markers. Using high-precision offset measurements and 36Cl cosmogenic nuclide dating, we present the first geochronologically determined Late Quaternary slip-rate for the EF. Our study focuses on the excellent exposures of offset alluvial fan surfaces, originating from the Aladağlar, a Late Quaternary glaciated mountain. Analysis of airborne orthophotogrametry and GNSS (Global Navigation Satellite System) surveys indicates 168 ± 2 m left lateral and 31 ± 1 m vertical displacements. In-situ terrestrial cosmogenic 36Cl geochronology obtained from eleven surface boulders provides a minimum abandonment/incision age of 104.2 ± 16.5 ka for the oldest offset alluvial fan surface. Our geomorphic observations together with Self-potential geophysical surveys revealed the presence of an unfaulted alluvial fan terrace, which allows us to constrain the timing of deformation. The abandonment/incision age of this fan is 64.5 ± 5.6 ka based on thirteen 36Cl depth profile samples. Accordingly, we obtained a geologic fault slip-rate of 4.2 ± 1.9 mm a- 1 horizontally and 0.8 ± 0.3 mm a- 1 vertically for the time frame between 104.2 ± 16.5 ka and 64.5 ± 5.6 ka. Our analysis indicates that the EF has not been producing a major surface breaking earthquake on the main strand at least since 64.5 ± 5.6 ka (mid-Late Pleistocene). This could be the result of abandonment of the main strand and accommodation of deformation by other faults within the EF. Nevertheless, a recently occurred (30 September 2011) low magnitude (ML: 4.3) left lateral strike-slip earthquake indicates recent seismic activity of the EF. Comparison of the recent GPS velocity field with the longer slip history along the CAFZ indicates a constant but low strain

  5. Cosmogenic /sup 22/Na and /sup 26/Al in samples of lunar ground from a drill column of Moon-24

    Energy Technology Data Exchange (ETDEWEB)

    Lavrukhina, A.K.; Povinets, P.; Ustinova, G.K.

    1984-01-01

    The method of low background (..beta..-..gamma..-..gamma..)-spectrometry without destruction of the sample has been used to measure /sup 22/Na and /sup 26/Al radioactivity in samples of lunar ground 24118.4-4, 24143.4-4 apd 24184.4-4 from the ''Luna-24'' drilling column. Equilibrium radioactivity of these cosmogenic isotopes is calculated by the analytic method. The analysis of theoretical and experimental data shows that at depths lower than approximately 40 cm from the lunar surface the drilling process did not bring about ground mixing in the drilling column. For the last million of years the regolite surface layer in the place of ''Luna-24'' landing remained pracically unchanged, i.e. has not been subjected to intensive effect of some mechanic processes on lunar surface. The average intensity of galactic cosmic rays with the rigidity > 0.5 GV for the last million years within the limits of approximtaely 20% remained stable and corresponded to their modern medium intensity 0.24 particlesxcm/sup -2/xc/sup -1/xsr/sup -1/. The average spectrum of galactic cosmic rays for a million years approximately corresponds to the average spectrum for 1962 or 1971.

  6. Unstable isotopes in a stable landscape?- Untangling Southern Africa's geological history with fission tracks and cosmogenic nuclides

    International Nuclear Information System (INIS)

    Belton, D.; Brown, R.; Fink, D.

    1998-01-01

    Full text: In the absence of direct evidence for burial and subsequent exposure of the land surface in the interior of Africa, researchers have argued for surface ages of several hundred million years. The proposition that landforms may have persisted at the surface for these extensive periods of time has a number of important implications. It suggests that the processes of tectonics and geomorphic evolution have been essentially absent for a period of up to 500 Ma. As a consequence, the persistence of these landscapes would require extremely low rates of weathering and erosion. Although this view of continental evolution has been widely held for several decades, recent studies suggest that continental interiors in Africa, Australia, Brazil and north America, have been subject to denudation in the order of several kilometres during the last 60 Ma. This study applies the complimentary techniques of apatite fission track and cosmogenic nuclide analysis, in an effort to measure both the long-term crustal-scale denudation and the short-term erosion rates, of which denudation is a function. We present preliminary data from the Zimbabwe Craton that illustrates the utility of such techniques in addressing both local and regional geological questions. The study provides a detailed picture of complex tectonic responses as well as large scale denudation over extended periods of time

  7. Age and evolution of diachronous erosion surfaces in the Amazon: Combining (U-Th)/He and cosmogenic 3He records

    Science.gov (United States)

    Monteiro, H. S.; Vasconcelos, P. M. P.; Farley, K. A.; Lopes, C. A. M.

    2018-05-01

    (U-Th)/He geochronology of two weathered plateaus in the Carajás Mountains, Pará, Brazil, reveals a history of weathering spanning from ca. 80 Ma to the present for this high elevation (∼720 m) land surface. Cosmogenic 3He measurements of hematite pebbles and blocks cemented onto the plateaus at two sites, N1 and S11D, yield erosion rates as low as 0.09 and 0.08 m Ma-1, respectively. Thus, these results confirm that the plateau surfaces are nearly immune to physical erosion for tens of millions of years. (U-Th)/He geochronology of ferruginous duricrusts blanketing the low elevation (250-100 m) plains surrounding the Carajás Mountains yield results consistently younger than ∼10 Ma. The geochronology results also reveal that the low elevation plain is diachronous, becoming progressively younger towards the receding plateaus. The spatial distribution of (U-Th)/He ages permits reconstruction of the history of scarp retreat for the Carajás landscape, showing that scarp retreat along major river valleys may have been as fast as 20 km Ma-1 during tectonically active and humid periods in the Cenozoic. The cessation of scarp retreat at some sites suggests that metamorphosed banded iron-formations and quartzites provide effective barriers to retreating escarpments, helping to preserve some of the oldest continuously exposed land surfaces on Earth.

  8. Measurement of the efficient cross section of the reaction 7Be(p, γ)8B at low energies and implications in the problem of solar neutrinos

    International Nuclear Information System (INIS)

    Hammache, Fairouz

    1999-01-01

    The 8 B produced inside the sun through the reaction 7 Be(p,γ) 8 B is the main, and even unique, source of high energy neutrinos detected in most solar neutrino detection experiments, except with Gallex and Sage. These experiments have all measured a neutrinos flux lower than the one predicted by solar models. Several explanations have been proposed to explain this deficit, but all require a precise knowledge of the efficient cross-section of the reaction 7 Be(p,γ) 8 B, because the neutrinos flux of 8 B is directly proportional to this reaction. The direct measurement of this cross section for the solar energy is impossible because of its low value (about 1 femto-barn). In order to get round this problem, the cross sections are measured at higher energy and extrapolated to the solar energy using a theoretical energy dependence. The 6 previous experimental determinations of the efficient cross section were shared in two distinct groups with differences of about 30% which leads to an uncertainty of the same order on the high energy neutrinos flux. The re-measurement of the cross section of this reaction with a better precision is thus of prime importance. A direct measurement of the cross section in the energy range comprised between 0.35 and 1.4 MeV (cm) has been performed first. These experiments have permitted the precise measurement of each parameter involved in the determination of the cross section. Then, measurements of the cross section have been carried out with the PAPAP accelerator at 185.8, 134.7 and 111.7 keV, the lowest mass center energy never reached before. The results are in excellent agreement with those obtained at higher energies. The value obtained by extrapolation of these data for the astrophysical factor S 17 (0) is 19.21.3 EV-B, which leads to a significant reduction of the uncertainty on the high energy neutrinos flux of 8 B. (J.S.)

  9. Cosmogenic radionuclides in the environment: 32Si in precipitation samples from the Jungfraujoch, production cross sections of 36Cl in Argon and modeling of the atmospheric 36Cl production

    International Nuclear Information System (INIS)

    Parrat, Y.

    1997-06-01

    The concentrations of the cosmogenic radionuclide 32 Si were measured in four fresh snow samples from the Jungfraujoch in the Swiss Alps (3450 m asl.) to study the feasibility of measuring this potential dating nuclide with Accelerator Mass Spectrometry. This technique could reduce drastically the amount of material needed for measurements of 32 Si concentrations in environmental samples in contrast to conventional radiometric detection. The measured 32 Si concentrations in the snow samples were between 1.84 and 6.28 μBql -1 . These values agree with other measurements of precipitation samples. The measured 32 Si/Si tot ratios ranged from 2.5.10 -17 to 2.3.10 -15 and were thus below the present detection limit of about 10 -14 , showing that at present it is not possible to carry out AMS measurements of 32 Si in precipitation samples. For the first time, experimental cross sections of the reaction 40 Ar(p,X) 36 Cl have been determined for the proton energy range 16-590 MeV. These cross sections were measured using a gas target, a novel method which was tested successfully by irradiating nitrogen targets to confirm literature values of the N(p,X) 7 Be and N(p,X) 10 Be cross sections. In fact, good agreement was found between the obtained cross sections with those using solid targets. Production of several radionuclides in the reaction of proton with nickel were also measured. Comparison of these cross sections with literature data proved that the proton flux measurements carried out with ionization chambers were very accurate. The excitation function of the reaction 40 Ar(p,X) 36 Cl exhibits two maxima at proton energies of 20 MeV for the (p,αn)reaction and 95 MeV for the (p,2p3n) reaction, with maximum cross sections of 105 mb and 53 mb, respectively. (author) figs., tabs., refs

  10. Comparison of the soil losses from 7Be measurements and the monitoring data by erosion pins and runoff plots in the Three Gorges Reservoir region, China

    International Nuclear Information System (INIS)

    Shi Zhonglin; Wen Anbang; Zhang Xinbao; Yan Dongchun

    2011-01-01

    The potential for using 7 Be measurements to document soil redistribution associated with a heavy rainfall was estimated using 7 Be method on a bare purple soil plot in the Three Gorges Reservoir region of China. The results were compared with direct measurement from traditional approaches of erosion pins and runoff plots. The study shows that estimation of soil losses from 7 Be are comparable with the monitoring results provided by erosion pins and runoff plots, and are also in agreement with the existing knowledge provided by 137 Cs measurements. The results obtained from this study demonstrated the potential for using 7 Be technique to quantify short-term erosion rates in these areas. - Highlights: → The soil redistribution associated with a heavy rainfall was estimated using 7 Be measurements. → Estimation of soil losses from 7 Be are comparable with the monitoring data provided by erosion pins and runoff plots. → The potential for using 7 Be measurements to quantify short-term erosion rates in purple soil areas was demonstrated.

  11. Behavior of 7Be and 210Pb deposited via rainwater on a coniferous forest, a broad-leaved forest, and grassland

    International Nuclear Information System (INIS)

    Osaki, S.; Sugihara, S.; Maeda, Y.; Osaki, T.

    2007-01-01

    Fall water, stem flow water and falling litter in a coniferous forest (C. japonica) and a broad-leaved forest (L. edulis), and rainwater on a grassland near the forests were collected, and their 7 Be and 210 Pb contents were measured. The average residence times of 7 Be and 210 Pb in the forest crowns were calculated from the balances of their radionuclides, those in the forest crown of C. japonica were 88 days for 7 Be and 9.2 years for 210 Pb, and those in the forest crown of L. edulis were 52 days and <1 year, respectively. (author)

  12. Measurements of neutron emission spectra and 7Be production in Li(d, n) and Be(d, n) reactions for 25 and 40 MeV deuterons

    International Nuclear Information System (INIS)

    Hagiwara, Masayuki; Baba, Mamoru; Aoki, Takao; Kawata, Naoki; Hirabayashi, Naoya; Itoga, Toshiro

    2003-01-01

    The neutron spectra in Li(d, n) and Be(d, n) reactions for Ed = 25, 40 MeV were measured from ∼1 MeV to highest energy of secondary neutrons at ten laboratory angles between 0- and 110-deg with the time-of-flight (TOF) method. In addition, the number of 7 Be accumulated in the targets was also measured by counting the γ-rays from 7 Be using a pure Ge detector to obtain 7 Be production cross-section and yields. (author)

  13. Comparison of the soil losses from (7)Be measurements and the monitoring data by erosion pins and runoff plots in the Three Gorges Reservoir region, China.

    Science.gov (United States)

    Shi, Zhonglin; Wen, Anbang; Zhang, Xinbao; Yan, Dongchun

    2011-10-01

    The potential for using (7)Be measurements to document soil redistribution associated with a heavy rainfall was estimated using (7)Be method on a bare purple soil plot in the Three Gorges Reservoir region of China. The results were compared with direct measurement from traditional approaches of erosion pins and runoff plots. The study shows that estimation of soil losses from (7)Be are comparable with the monitoring results provided by erosion pins and runoff plots, and are also in agreement with the existing knowledge provided by 137Cs measurements. The results obtained from this study demonstrated the potential for using (7)Be technique to quantify short-term erosion rates in these areas. Copyright © 2011 Elsevier Ltd. All rights reserved.

  14. Cosmogenic 3He in hematite and goethite from Brazilian "canga" duricrust demonstrates the extreme stability of these surfaces

    Science.gov (United States)

    Shuster, David L.; Farley, Kenneth A.; Vasconcelos, Paulo M.; Balco, Greg; Monteiro, Hevelyn S.; Waltenberg, Kathryn; Stone, John O.

    2012-05-01

    Helium isotopes were measured in hematite and goethite samples from several lateritiric duricrusts (canga) developed on banded iron formations. These samples uniformly have high 3He concentrations which must arise from long periods of cosmic ray exposure. From coexisting phases from the Quadrilátero Ferrífero in east central Brazil, we determined the ratio of cosmogenic 3He in hematite to that of 21Ne in quartz to be 3.96 ± 0.19. Combined with best current estimates of the 21Ne production rate in quartz, this ratio implies a sea-level high latitude (SLHL) 3He production rate in hematite of 68.1 ± 8.1 atoms/g/yr; from the chemical composition we estimate the 3He production rate in goethite to be ~ 5% higher. We use these production rate estimates to interpret 3He concentrations measured in goethite and hematite from a ~ 10 m depth profile collected from a surface canga in Carajás, in the Amazon basin of Brazil. We find that the Carajás canga has experienced a very low rate of surface erosion (~ 0.16-0.54 m/Myr) over at least the last few millions of years. This iron-rich canga surface is remarkably resistant to erosion despite its location in a wet tropical environment. Details of the depth profile suggest that despite its stability, the canga has also been internally dynamic (translocation of material; solution and reprecipitation) over million-year timescales.

  15. Quantifying Quaternary Deformation in the Eastern Cordillera of the Colombian Andes Using Cosmogenic Nuclide Geochronology and Fluvial Geomorphology

    Science.gov (United States)

    Dalman, E.; Taylor, M. H.; Veloza-fajardo, G.; Mora, A.

    2014-12-01

    Northwest South America is actively deforming through the interaction between the Nazca, South American, and Caribbean plates. Though the Colombian Andes are well studied, much uncertainty remains in the rate of Quaternary deformation along the east directed frontal thrust faults hundreds of kilometers in board from the subduction zones. The eastern foothills of the Eastern Cordillera (EC) preserve deformed landforms, allowing us to quantify incision rates. Using 10Be in-situ terrestrial cosmogenic nuclide (TCN) geochronology, we dated 2 deformed fluvial terraces in the hanging wall of the Guaicaramo thrust fault. From the 10Be concentration and terrace profile relative to local base level, we calculated incision rates. We present a reconstructed slip history of the Guaicaramo thrust fault and its Quaternary slip rate. Furthermore, to quantify the regional Quaternary deformation, we look at the fluvial response to tectonic uplift. Approximately 20 streams along the eastern foothills of the Eastern Cordillera (EC) were studied using a digital elevation model (DEM). From the DEM, longitudinal profiles were created and normalized channel steepness (Ksn) values calculated from plots of drainage area vs. slope. Knickpoints in the longitudinal profiles can record transient perturbations or differential uplift. Calculated Ksn values indicate that the EC is experiencing high rates of uplift, with the highest mean Ksn values occurring in the Cocuy region. Mean channel steepness values along strike of the foothills are related to increasing uplift rates from south to north. In contrast, we suggest that high channel steepness values in the south appear to be controlled by high rates of annual precipitation.

  16. Cosmogenic radionuclides and mineralogical properties of the Chelyabinsk (LL5) meteorite: What do we learn about the meteoroid?

    Science.gov (United States)

    Povinec, Pavel P.; Laubenstein, Matthias; Jull, A. J. Timothy; FerrièRe, Ludovic; BrandstäTter, Franz; Sýkora, Ivan; Masarik, Jozef; BeåO, Juraj; KováčIk, Andrej; Topa, Dan; Koeberl, Christian

    2015-02-01

    On February 15, 2013, after the observation of a brilliant fireball and a spectacular airburst over the southern Ural region (Russia), thousands of stones fell and were rapidly recovered, bringing some extremely fresh material for scientific investigations. We undertook a multidisciplinary study of a dozen stones of the Chelyabinsk meteorite, including petrographic and microprobe investigations to unravel intrinsic characteristics of this meteorite. We also study the short and long-lived cosmogenic radionuclides to characterize the initial meteoroid size and exposure age. Petrographic observations, as well as the mineral compositions obtained by electron microprobe analyses, allow us to confirm the classification of the Chelyabinsk meteorite as an LL5 chondrite. The fragments studied, a few of which are impact melt rocks, contain abundant shock melt veins and melt pockets. It is likely that the catastrophic explosion and fragmentation of the Chelyabinsk meteoroid into thousands of stones was in part determined by the initial state of the meteoroid. The radionuclide results obtained show a wide range of concentrations of 14C, 22Na, 26Al, 54Mn, 57Co, 58Co, and 60Co, which indicate that the pre-atmospheric object had a radius >5 m, consistent with other size estimates based on the magnitude of the airburst caused by the atmospheric entry and breakup of the Chelyabinsk meteoroid. Considering the observed 26Al activities of the investigated samples, Monte Carlo simulations, and taking into account the 26Al half-life (0.717 Myr), the cosmic-ray exposure age of the Chelyabinsk meteorite is estimated to be 1.2 ± 0.2 Myr. In contrast to the other radionuclides, 14C showed a very large range only consistent with most samples having been exposed to anthropogenic sources of 14C, which we associate with radioactive contamination of the Chelyabinsk region by past nuclear accidents and waste disposal, which has also been confirmed by elevated levels of anthropogenic 137Cs and

  17. Use of 7Be as a sediment tracer: a scope for testing and refining key assumptions related to its adsorption on a catchment scale

    Science.gov (United States)

    Ryken, Nick; Al-Barri, Bashar; Blake, Will; Taylor, Alex; Boeckx, Pascal; Verdoodt, Ann

    2014-05-01

    To date the use of Beryllium-7 (7Be) as a sediment tracer on catchment scale is largely understudied, although several studies applied the ratio 7Be/137Cs or 7Be/210Pbex for sediment source fingerprinting. Several key assumptions, (1) spatially uniform fallout, (2) immediate adsorption upon contact with the soil and (3) irreversible adsorption by the soil, must hold if 7Be is to be used as a sediment tracer. However, recent studies have raised questions about the validity of these assumptions in the changing environments on a catchment scale. In this study three representative soil types of the Mariaborrebeek catchment, a small watershed located in the Flemish Ardennes in Belgium, were collected to assess the adsorption rate of 7Be on the soil surface in this catchment. In a laboratory experiment, soil samples were equilibrated with a stable Be solution of 1 mg l-1 at a soil:solution ratio of 1:10 and the adsorption of Be was measured at different time intervals. Furthermore, different amendments were applied to assess the impact of soil pH, fertilizer and organic matter on the adsorption of Be. Preliminary results confirm a rapid and almost complete Be adsorption and a negative correlation between pH and Be adsorption. The results of this study might lead to the formulation of interpretation guidelines for the use of 7Be to assess short-term soil redistribution and sediment source fingerprinting on catchment scale.

  18. Short-term variability of 7Be atmospheric deposition and watershed response in a Pacific coastal stream, Monterey Bay, California, USA

    Science.gov (United States)

    Conaway, Christopher H.; Storlazzi, Curt D.; Draut, Amy E.; Swarzenski, Peter W.

    2013-01-01

    Beryllium-7 is a powerful and commonly used tracer for environmental processes such as watershed sediment provenance, soil erosion, fluvial and nearshore sediment cycling, and atmospheric fallout. However, few studies have quantified temporal or spatial variability of 7Be accumulation from atmospheric fallout, and parameters that would better define the uses and limitations of this geochemical tracer. We investigated the abundance and variability of 7Be in atmospheric deposition in both rain events and dry periods, and in stream surface-water samples collected over a ten-month interval at sites near northern Monterey Bay (37°N, 122°W) on the central California coast, a region characterized by a rainy winters, dry summers, and small mountainous streams with flashy hydrology. The range of 7Be activity in rainwater samples from the main sampling site was 1.3–4.4 Bq L−1, with a mean (±standard deviation) of 2.2 ± 0.9 Bq L−1, and a volume-weighted average of 2.0 Bq L−1. The range of wet atmospheric deposition was 18–188 Bq m−2 per rain event, with a mean of 72 ± 53 Bq m−2. Dry deposition fluxes of 7Be ranged from less than 0.01 up to 0.45 Bq m−2 d−1, with an estimated dry season deposition of 7 Bq m−2 month−1. Annualized 7Be atmospheric deposition was approximately 1900 Bq m−2 yr−1, with most deposition via rainwater (>95%) and little via dry deposition. Overall, these activities and deposition fluxes are similar to values found in other coastal locations with comparable latitude and Mediterranean-type climate. Particulate 7Be values in the surface water of the San Lorenzo River in Santa Cruz, California, ranged from −1 to 0.6 Bq g−1, with a median activity of 0.26 Bq g−1. A large storm event in January 2010 characterized by prolonged flooding resulted in the entrainment of 7Be-depleted sediment, presumably from substantial erosion in the watershed. There were too few particulate 7Be data over the storm to accurately model a 7Be load

  19. Cosmogenic excess of 40K and the flux of fast neutrons in meteorites

    International Nuclear Information System (INIS)

    Stegmann, W.; Begemann, F.

    1975-01-01

    Results are reported of a mass spectrometric investigation of the content and isotopic composition of potassium from the mesosiderite Emery (silicate phase) and the chondrite Elenovka (bulk). Normalized to the Nier value of 39 K/ 41 K = 13.47, the 40 K in Emery (K-content 220 +- 25 ppm) was found to be enriched by (4.03 +- 0.30)%, the potassium from Elenovka (760 +- 50 ppm) to be indistinguishable from terrestrial potassium. Evidence is presented that the excess 40 K in the silicates from Emery (Ca-content 6.06 weight %) has been produced essentially by secondary cosmic ray neutrons via the 40 Ca(n,p)-reaction. The total excess of (2.57 +- 0.39) x 10 14 40 K-atoms/gCa together with the excitation function of the 40 Ca(n,p)-reaction and the neutron flux spectrum of Arnold, Honda and Lal yields a dose of fast neutrons (2 MeV 16 neutrons/cm 2 and an average flux during the cosmic ray exposure age T = (134 +- 12) Myrs of PHI = (17.4 +- 3.1) neutrons/cm 2 sec. (orig./BJ) [de

  20. Hydrodynamic Simulations of Classical Nova explosions: predictions of 7Be and 7Li production and the growth to the Chandrasekhar Limit

    Science.gov (United States)

    Starrfield, Sumner; Bose, Maitrayee; Iliadis, Christian; Hix, William R.; Wagner, R. Mark; Woodward, Charles E.; Jose', Jordi; Hernanz, Margarita

    2018-01-01

    We have continued our studies of Classical Nova explosions by following the evolution of thermonuclear runaways (TNRs) on Carbon Oxygen white dwarfs (WDs). We have varied both the mass of the WD and the composition of the accreted material. We now rely on the results of multi-D studies of TNRs in WDs that accrete only Solar matter. They find that mixing with the core occurs after the TNR is well underway, reaching enrichment levels in agreement with observations of the ejecta abundances. We, therefore, accrete only Solar matter with NOVA (our 1-D, fully implicit, hydro code) until the TNR is initiated and then switch the accreted composition to a mixed composition: either 25% core and 75% Solar or 50% core and 50% Solar. Because the amount of accreted material is inversely proportional to the initial 12C abundance, by accreting Solar matter the amount of material taking part in the outburst is larger than if we had used mixed material from the beginning. We follow the TNR through the peak and tabulate the amount of ejected gases, their velocities and abundances. We also predict the amount of 7Li and 7Be produced and ejected by the explosion and compare our predictions to the observations in a companion poster describing the LBT measurements of 7Li in V5668 Sgr. We also compare our abundance predictions to those measured in pre-solar grains that may arise from Classical Nova explosions. Our predictions are also compared to results with SHIVA (Josè and Hernanz). Finally, many of these simulations eject significantly less mass than accreted and, therefore, the WD is growing in mass toward the Chandrasekhar Limit. This suggests that the single degenerate scenario is still a viable option for SN Ia progenitors. This work was supported in part by NASA under the Astrophysics Theory Program grant 14-ATP14-0007 and the U.S. DOE under Contract No. DE-FG02- 97ER41041. SS acknowledges partial support from NASA and HST grants to ASU and WRH is supported by the U.S. Department

  1. Short-term variability of 7Be atmospheric deposition and watershed response in a Pacific coastal stream, Monterey Bay, California, USA

    International Nuclear Information System (INIS)

    Conaway, Christopher H.; Storlazzi, Curt D.; Draut, Amy E.; Swarzenski, Peter W.

    2013-01-01

    Beryllium-7 is a powerful and commonly used tracer for environmental processes such as watershed sediment provenance, soil erosion, fluvial and nearshore sediment cycling, and atmospheric fallout. However, few studies have quantified temporal or spatial variability of 7 Be accumulation from atmospheric fallout, and parameters that would better define the uses and limitations of this geochemical tracer. We investigated the abundance and variability of 7 Be in atmospheric deposition in both rain events and dry periods, and in stream surface-water samples collected over a ten-month interval at sites near northern Monterey Bay (37°N, 122°W) on the central California coast, a region characterized by a rainy winters, dry summers, and small mountainous streams with flashy hydrology. The range of 7 Be activity in rainwater samples from the main sampling site was 1.3–4.4 Bq L −1 , with a mean (±standard deviation) of 2.2 ± 0.9 Bq L −1 , and a volume-weighted average of 2.0 Bq L −1 . The range of wet atmospheric deposition was 18–188 Bq m −2 per rain event, with a mean of 72 ± 53 Bq m −2 . Dry deposition fluxes of 7 Be ranged from less than 0.01 up to 0.45 Bq m −2 d −1 , with an estimated dry season deposition of 7 Bq m −2 month −1 . Annualized 7 Be atmospheric deposition was approximately 1900 Bq m −2 yr −1 , with most deposition via rainwater (>95%) and little via dry deposition. Overall, these activities and deposition fluxes are similar to values found in other coastal locations with comparable latitude and Mediterranean-type climate. Particulate 7 Be values in the surface water of the San Lorenzo River in Santa Cruz, California, ranged from −1 to 0.6 Bq g −1 , with a median activity of 0.26 Bq g −1 . A large storm event in January 2010 characterized by prolonged flooding resulted in the entrainment of 7 Be-depleted sediment, presumably from substantial erosion in the watershed. There were too few particulate 7 Be data over the storm

  2. Spatial and temporal variability of 7Be and 210Pb wet deposition during four successive monsoon storms in a catchment of northern Laos

    International Nuclear Information System (INIS)

    Gourdin, E.; Evrard, O.; Huon, S.; Reyss, J.-L.; Ribolzi, O.; Bariac, T.; Sengtaheuanghoung, O.; Ayrault, S.

    2014-01-01

    Fallout radionuclides 7 Be and 210 Pb have been identified as potentially relevant temporal tracers for studying soil particles dynamics (surface vs. subsurface sources contribution; remobilization of in-channel sediment) during erosive events in river catchments. An increasing number of studies compared 7 Be: 210 Pb activity ratio in rainwater and sediment to estimate percentages of freshly eroded particles. However, the lack of data regarding the spatial and temporal variability of radionuclide wet deposition during individual storms has been identified as one of the main gaps in these estimates. In order to determine these key parameters, rainwater samples were collected at three stations during four storms that occurred at the beginning of the monsoon (June 2013) in the Houay Xon mountainous catchment in northern Laos. Rainwater 7 Be and 210 Pb activities measured using very low background hyperpure Germanium detectors ranged from 0.05 to 1.72 Bq L −1 and 0.02 to 0.26 Bq L −1 , respectively. Water δ 18 O were determined on the same samples. Total rainfall amount of the four sampled storms ranged from 4.8 to 26.4 mm (51 mm in total) at the time-fractionated collection point. Corresponding cumulative 7 Be and 210 Pb wet depositions during the sampling period were 17.6 and 2.9 Bq m −2 , respectively. The 7 Be: 210 Pb activity ratio varied (1) in space from 6 to 9 for daily deposition and (2) in time from 3 to 12 for samples successively collected. Intra-event evolution of rainwater 7 Be and 210 Pb activities as well as δ 18 O highlighted the progressive depletion of local infra-cloud atmosphere radionuclide stock with time (washout), which remains consistent with a Raleigh-type distillation process for water vapour. Intra-storm ratio increasing with time showed the increasing contribution of rainout scavenging. Implications of such variability for soil particle labelling and erosion studies are briefly discussed and recommendations are formulated for the

  3. Tracking paraglacial sediment with cosmogenic 10Be using an example from the northwest Scottish Highlands

    Science.gov (United States)

    Fame, Michelle L.; Owen, Lewis A.; Spotila, James A.; Dortch, Jason M.; Caffee, Marc W.

    2018-02-01

    Beryllium-10 concentrations in samples of sediment and bedrock from five study sites across the Scottish Highlands trace paraglacial sediment sources and define the nature of glacial erosion for the late Quaternary. Exposure ages derived from 10Be concentrations in ridge and lower elevation bedrock range from 10 to 33 ka, which suggest that polythermal ice and warm based ice were primarily responsible for producing glacial sediment. Comparisons of 10Be concentrations between catchment-wide sediment (2.06 ± 0.34 × 104 to 11.24 ± 1.54 × 104 atoms g-1 SiO2; n = 33), near surface deposits (2.71 ± 0.33 × 104 to 3.48 ± 0.49 × 104 atoms g-1 SiO2; n = 6), 4-m-thick deep till (0.68 × 10410Be atoms g-1 SiO2; n = 1), ridge bedrock (8.93 ± 0.47 × 104 to 34.05 ± 1.66 × 104 atoms g-1 SiO2; n = 20), and lower elevation polished bedrock (6.74 ± 0.67 × 104 to 12.65 ± 0.7 × 104 atoms g-1 SiO2, n = 5) indicate that most sand fluxing through catchments in the Scottish Highlands is sourced from the remobilization and vertical mixing of near surface deposits. These findings indicate that glaciogenic material continues to dominate paraglacial sediment budgets more than 11 ka after deglaciation.

  4. Accuracy of 9Be-data and its influence on 10Be cosmogenic nuclide data

    International Nuclear Information System (INIS)

    Merchel, S.; Schaefer, U.; Bremser, W.; Recknagel, S.; Bourles, D.L.; Leanni, L.; Czeslik, U.; Erzinger, J.; Kummer, N.A.; Merkel, B.

    2013-01-01

    A 9 Be-solution has been chemically prepared from phenakite (Be 2 SiO 4 ) mineral grains as commercial 9 Be-solutions are too high in long-lived 10 Be. The solution is intended to be used as a carrier for radiochemical separation of 10 Be to be measured by accelerator mass spectrometry (AMS). Thus, accurate data of the 9 Be-concentration of this solution is essential to guarantee for high-accuracy 10 Be data in the future. After devastating preliminary results (∼8 % standard deviation), eight laboratories finally produced twelve individual results by four different analytical methods. A certain lab and method bias might be identified by sophisticated statistical evaluation. Some laboratories also (grossly) underestimate their uncertainties. Thus, the simple weighted mean of this round-robin exercise needed to be corrected by introducing additional allowances (Paule-Mandel-approach). The final result has been calculated to (2,246 ± 11) μg 9 Be/(g solution) with a reasonably low weighted standard deviation of 0.49 %. The maximum deviation of a single lab value from the weighted mean is 2.4 % when removing one Grubbs outlier (11 % off from the mean) from the data set. As 10 Be-data, which is usually calculated from measured 10 Be/ 9 Be by AMS and stable 9 Be, cannot be more accurate than the determined 9 Be-concentration, it seems highly advisable to establish or improve quality assurance by having self-made carrier-solutions analysed at more than a single lab and regularly taking part in round-robin exercises. (author)

  5. Cosmogenic 10Be Dating of Early and Latest Holocene Moraines on Nevado Salcantay in the Southern Peruvian Andes

    Science.gov (United States)

    Licciardi, J. M.; Schaefer, J. M.; Lund, D. C.

    2007-12-01

    A two-fold sequence of nested lateral and end moraines was mapped in a glacial trough emanating from the southwest flank of Nevado Salcantay (6271 m; ~13°S latitude), the highest peak in the Cordillera Vilcabamba of southern Peru. The field area is situated 25 km due south of the archaeological site of Machu Picchu. Outer and inner moraines in the sequence were deposited by valley glaciers that terminated ~5 km and ~3 km, respectively, from their headwall on the Salcantay summit massif. Cosmogenic 10Be surface exposure dating of granitic boulders sampled on the Salcantay moraines is underway and has provided the first numerical ages for these deposits. Initial results indicate ages of 8.1 ± 0.1 10Be ka for the outer moraine and 200 ± 20 10Be years for the sharp-crested inner moraine. These ages are derived using the CRONUS-Earth 10Be exposure age calculator (version 2.0) and expressed with respect to the Lal- Stone production rate scaling scheme using the standard atmosphere. The outer and inner moraine ages correspond to glacial events during the early and latest Holocene, respectively. Further 10Be dating of the mapped moraines and similar deposits observed in adjacent drainages on Nevado Salcantay is anticipated to yield a high-resolution chronology of valley glaciation in this segment of the southern Peruvian Andes. The new results bridge an important gap between existing Andean glacier records to the north and south, and complement available ice core and lacustrine paleoclimate records in the vicinity, thereby expanding spatial and temporal coverage for identifying patterns of Holocene climate change in the tropical Andes. Notably, the inner moraine age correlates with the timing of the Little Ice Age as defined in northern mid- and high latitude glacier records, and suggests considerable expansion of valley glaciers in the southern Peruvian Andes during this climatic minimum. Apart from their paleoclimatic significance, the initial results also demonstrate

  6. Seismic Supercycles of Normal Faults in Central Italy over Various Time Scales Revealed by 36Cl Cosmogenic Dating

    Science.gov (United States)

    Benedetti, L. C.; Tesson, J.; Perouse, E.; Puliti, I.; Fleury, J.; Rizza, M.; Billant, J.; Pace, B.

    2017-12-01

    The use of 36Cl cosmogenic nuclide as a paleoseismological tool for normal faults in the Mediterranean has revolutionized our understanding of their seismic cycle (Gran Mitchell et al. 2001, Benedetti et al. 2002). Here we synthetized results obtained on 13 faults in Central Italy. Those records cover a period of 8 to 45 ka. The mean recurrence time of retrieved seismic events is 5.5 ±6 ka, with a mean slip per event of 2.5 ± 1.8 m and a mean slip-rate from 0.1 to 2.4 mm/yr. Most retrieved events correspond to single events according to scaling relationships. This is also supported by the 2 m-high co-seismic slip observed on the Mt Vettore fault after the October 30, 2016 M6.5 earthquake in Central Italy (EMERGEO working group). Our results suggest that all faults have experienced one or several periods of slip acceleration with bursts of seismic activity, associated with very high slip-rate of 1.7-9 mm/yr, corresponding to 2-20 times their long-term slip-rate. The duration of those bursts is variable from a fault to another (from recurrence time. This might suggest that the seismic activity of those faults could be controlled by their intrinsic properties (e.g. long-term slip-rate, fault-length, state of structural maturity). Our results also show events clustering with several faults rupturing in less than 500 yrs on adjacent or distant faults within the studied area. The Norcia-Amatrice seismic sequence, ≈ 50 km north of our study area, also evidenced this clustering behaviour, with over the last 20 yrs several successive events of Mw 5 to 6.5 (from north to south: Colfiorito 1997 Mw6.0, Norcia 2016 Mw6.5, L'Aquila 2009 Mw6.3), rupturing various fault systems, over a total length of ≈100 km. This sequence will allow to better understand earthquake kinematics and spatiotemporal slip distribution during those seismic bursts.

  7. Cosmogenic 10Be and 26Al exposure ages of tors and erratics, Cairngorm Mountains, Scotland: Timescales for the development of a classic landscape of selective linear glacial erosion

    Science.gov (United States)

    Phillips, W.M.; Hall, A.M.; Mottram, R.; Fifield, L.K.; Sugden, D.E.

    2006-01-01

    The occurrence of tors within glaciated regions has been widely cited as evidence for the preservation of relic pre-Quaternary landscapes beneath protective covers of non-erosive dry-based ice. Here, we test for the preservation of pre-Quaternary landscapes with cosmogenic surface exposure dating of tors. Numerous granite tors are present on summit plateaus in the Cairngorm Mountains of Scotland where they were covered by local ice caps many times during the Pleistocene. Cosmogenic 10Be and 26Al data together with geomorphic relationships reveal that these landforms are more dynamic and younger than previously suspected. Many Cairngorm tors have been bulldozed and toppled along horizontal joints by ice motion, leaving event surfaces on tor remnants and erratics that can be dated with cosmogenic nuclides. As the surfaces have been subject to episodic burial by ice, an exposure model based upon ice and marine sediment core proxies for local glacial cover is necessary to interpret the cosmogenic nuclide data. Exposure ages and weathering characteristics of tors are closely correlated. Glacially modified tors and boulder erratics with slightly weathered surfaces have 10Be exposure ages of about 15 to 43 ka. Nuclide inheritance is present in many of these surfaces. Correction for inheritance indicates that the eastern Cairngorms were deglaciated at 15.6 ?? 0.9 ka. Glacially modified tors with moderate to advanced weathering features have 10Be exposure ages of 19 to 92 ka. These surfaces were only slightly modified during the last glacial cycle and gained much of their exposure during the interstadial of marine Oxygen Isotope Stage 5 or earlier. Tors lacking evidence of glacial modification and exhibiting advanced weathering have 10Be exposure ages between 52 and 297 ka. Nuclide concentrations in these surfaces are probably controlled by bedrock erosion rates instead of discrete glacial events. Maximum erosion rates estimated from 10Be range from 2.8 to 12.0 mm/ka, with

  8. Catchment-wide weathering and erosion rates of mafic, ultramafic, and granitic rock from cosmogenic meteoric 10Be/9Be ratios

    Science.gov (United States)

    Dannhaus, N.; Wittmann, H.; Krám, P.; Christl, M.; von Blanckenburg, F.

    2018-02-01

    Quantifying rates of weathering and erosion of mafic rocks is essential for estimating changes to the oceans alkalinity budget that plays a significant role in regulating atmospheric CO2 levels. In this study, we present catchment-wide rates of weathering, erosion, and denudation measured with cosmogenic nuclides in mafic and ultramafic rock. We use the ratio of the meteoric cosmogenic nuclide 10Be, deposited from the atmosphere onto the weathering zone, to stable 9Be, a trace metal released by silicate weathering. We tested this approach in stream sediment and water from three upland forested catchments in the north-west Czech Republic. The catchments are underlain by felsic (granite), mafic (amphibolite) and ultramafic (serpentinite) lithologies. Due to acid rain deposition in the 20th century, the waters in the granite catchment exhibit acidic pH, whereas waters in the mafic catchments exhibit neutral to alkaline pH values due to their acid buffering capability. The atmospheric depositional 10Be flux is estimated to be balanced with the streams' dissolved and particulate meteoric 10Be export flux to within a factor of two. We suggest a correlation method to derive bedrock Be concentrations, required as an input parameter, which are highly heterogeneous in these small catchments. Derived Earth surface metrics comprise (1) Denudation rates calculated from the 10Be/9Be ratio of the "reactive" Be (meaning sorbed to mineral surfaces) range between 110 and 185 t km-2 y-1 (40 and 70 mm ky-1). These rates are similar to denudation rates we obtained from in situ-cosmogenic 10Be in quartz minerals present in the bedrock or in quartz veins in the felsic and the mafic catchment. (2) The degree of weathering, calculated from the fraction of 9Be released from primary minerals as a new proxy, is about 40-50% in the mafic catchments, and 10% in the granitic catchment. Lastly, (3) erosion rates were calculated from 10Be concentrations in river sediment and corrected for sorting

  9. Tectonic-magmatic interplay during the early stages of oceanic rifting: temporal constraints from cosmogenic 3He dating in the Dabbahu rift segment, Afar

    Science.gov (United States)

    Williams, A.; Pik, R.; Burnard, P.; Medynski, S.; Yirgu, G.

    2009-12-01

    The Afar Rift in Ethiopia is one of the only subaerial locations in the world where the transition from continental break-up to oceanic-spreading can be observed. Extension and volcanism in the Afar is concentrated in tectono-magmatic segments (TMS), similar in size and morphology to those that characterize mid-ocean ridge systems. However, unlike their submarine equivalents, the Afar TMS contain large silicic central volcanoes, implying that magma differentiation plays an important role in the early evolution of the oceanic rifts. The Dabbahu TMS at the south of the western Afar rift system has recently been the site of significant activity. A massive seismic event in late 2005, triggered by dyke injection, heralded the onset of new rifting period. Volcanism associated with the periods of magma-driven extension has been both silicic (explosive) and basaltic (fissural). The most recent activity in the Afar thus testifies to the close interplay of tectonics and magmatism in rifting environments. In an effort to decipher the long-term structural and volcanic evolution of Dabbahu TMS, we combine cosmogenic 3He dating with geological interpretation of ASTER images and major and trace element analyses of the main volcanic units present. The cosmogenic dating method has advantages over other geochronological tools in that we can target both volcanic and tectonic surfaces of a few Kyr to several Myr age. At Baddi Volcano, an off-axis stratovolcano located west of the Dabbahu rift-axis, basaltic lava flows overlie an acidic base, previously dated at 290 ka using the K-Ar technique (Lahitte et al., 2003). Following preliminary sampling in 2007, we determined cosmogenic 3He ages of 57 ka and 45 ka for two basaltic flows on the flanks of Baddi. We now investigate whether this presumed replenishment of the Baddi magma chamber represents a replenishment of the entire sub-rift plumbing system, and how this in turn relates to the onset and maintenance of surface deformation

  10. Cosmogenic 10Be production rate calibrated against 3He in the high Tropical Andes (3800-4900 m, 20-22° S)

    Science.gov (United States)

    Blard, P.-H.; Braucher, R.; Lavé, J.; Bourlès, D.

    2013-11-01

    Many geomorphologic applications, notably glacier chronologies, require improvements in both the precision and the accuracy of the cosmogenic dating tool. Of particular importance is the need to better constrain the spatial variability of the cosmogenic nuclides production rates at high elevation and low latitudes. One strategy that can be adopted for this is to couple absolute calibrations, from independently dated surfaces, with cross-calibration studies, performed by measuring several cosmogenic nuclides in the same rock. In the present study, we report the highest-elevation (>4800 m) cross-calibration published to date, comprising measurements of cosmogenic 3He and 10Be in cogenetic pyroxene and quartz. The samples were collected from six dacitic moraine boulders, exposed from 32 to 65 ka at 4820 m on the flanks of the Uturuncu volcano (22° S, 67° W), Southern Lipez (Bolivia). The samples yield a remarkably tight cluster of 3He-10Be production ratios, with a weighted mean of 33.3±0.9 (1σ). This production ratio is undistinguishable, within uncertainties, from the 3He-10Be production ratio of 32.3±0.9 determined in the same mineral pair at low elevation (1333 m) by Amidon et al. (2009). These results agree at the 1σ level and suggest that any hypothetical increase of the 3He-10Be production ratio in pyroxene and quartz is likely to be lower than 5% over this elevation range (1000-5000 m). Moreover, the production ratio is almost insensitive to the Li content of the pyroxene (20 to 50 ppm Li), suggesting that the cosmogenic thermal neutron production of 3He is very low in this setting. The high-elevation 3He-10Be production ratio is used in combination with a local determination of the 3He production rate in the high Central Altiplano (3800 m) (Blard et al., 2013) to establish a local 10Be production rate of 30.0±1.4 at g yr at 3800 m and 20° S. After scaling to sea-level high latitude with the time-dependent Lal/Stone model, this yields a 10Be production

  11. Measurement of the efficient cross section of the reaction {sup 7}Be(p, {gamma}){sup 8}B at low energies and implications in the problem of solar neutrinos; Mesures de la section efficace de la reaction {sup 7}Be(p,{gamma}){sup 8}B a basses energies et implications dans le probleme des neutrinos solaires

    Energy Technology Data Exchange (ETDEWEB)

    Hammache, Fairouz

    1999-07-01

    The {sup 8}B produced inside the sun through the reaction {sup 7}Be(p,{gamma}){sup 8}B is the main, and even unique, source of high energy neutrinos detected in most solar neutrino detection experiments, except with Gallex and Sage. These experiments have all measured a neutrinos flux lower than the one predicted by solar models. Several explanations have been proposed to explain this deficit, but all require a precise knowledge of the efficient cross-section of the reaction {sup 7}Be(p,{gamma}){sup 8}B, because the neutrinos flux of {sup 8}B is directly proportional to this reaction. The direct measurement of this cross section for the solar energy is impossible because of its low value (about 1 femto-barn). In order to get round this problem, the cross sections are measured at higher energy and extrapolated to the solar energy using a theoretical energy dependence. The 6 previous experimental determinations of the efficient cross section were shared in two distinct groups with differences of about 30% which leads to an uncertainty of the same order on the high energy neutrinos flux. The re-measurement of the cross section of this reaction with a better precision is thus of prime importance. A direct measurement of the cross section in the energy range comprised between 0.35 and 1.4 MeV (cm) has been performed first. These experiments have permitted the precise measurement of each parameter involved in the determination of the cross section. Then, measurements of the cross section have been carried out with the PAPAP accelerator at 185.8, 134.7 and 111.7 keV, the lowest mass center energy never reached before. The results are in excellent agreement with those obtained at higher energies. The value obtained by extrapolation of these data for the astrophysical factor S{sub 17}(0) is 19.21.3 EV-B, which leads to a significant reduction of the uncertainty on the high energy neutrinos flux of {sup 8}B. (J.S.)

  12. Production of mirror nuclei 7Li and 7Be in 16Op interactions at a momentum of 3.25 GeV/c per nucleon

    International Nuclear Information System (INIS)

    Olimov, K.; Glagolev, V. V.; Lutpullaev, S. L.; Kurbanov, A.; Olimov, A. K.; Petrov, V. I.; Yuldashev, A. A.

    2011-01-01

    Results of a comparative analysis of processes leading to the production of mirror nuclei 7 Li and 7 Be in 16 Op collisions at a momentum of 3.25 GeV/c per nucleon are presented. A comparison of associated multiplicities of accompanying particles is performed. The first results on the mean multiplicity of neutrons appearing as fragments are described.

  13. $^7Be(n,\\alpha)^4He$ reaction and the Cosmological Lithium Problem: measurement of the cross section in a wide energy range at n_TOF (CERN)

    CERN Document Server

    Barbagallo, M.; Cosentino, L.; Maugeri, E.; Heinitz, S.; Mengoni, A.; Dressler, R.; Schumann, D.; Käppeler, F.; Colonna, N.; Finocchiaro, P.; Ayranov, M.; Damone, L.; Kivel, N.; Aberle, O.; Altstadt, S.; Andrzejewski, J.; Audouin, L.; Bacak, M.; Balibrea-Correa, J.; Barros, S.; Bécares, V.; Bečvář, F.; Beinrucker, C.; Berthoumieux, E.; Billowes, J.; Bosnar, D.; Brugger, M.; Caamaño, M.; Calviani, M.; Calviño, F.; Cano-Ott, D.; Cardella, R.; Casanovas, A.; Castelluccio, D. M.; Cerutti, F.; Chen, Y. H.; Chiaveri, E.; Cortés, G.; Cortés-Giraldo, M. A.; Cristallo, S.; Diakaki, M.; Domingo-Pardo, C.; Dupont, E.; Duran, I.; Fernandez-Dominguez, B.; Ferrari, A.; Ferreira, P.; Furman, W.; Ganesan, S.; García-Rios, A.; Gawlik, A.; Glodariu, T.; Göbel, K.; Gonçalves, I. F.; González-Romero, E.; Griesmayer, E.; Guerrero, C.; Gunsing, F.; Harada, H.; Heftrich, T.; Heyse, J.; Jenkins, D. G.; Jericha, E.; Katabuchi, T.; Kavrigin, P.; Kimura, A.; Kokkoris, M.; Krtička, M.; Leal-Cidoncha, E.; Lerendegui, J.; Lederer, C.; Leeb, H.; Lo Meo, S.; Lonsdale, S. J.; Losito, R.; Macina, D.; Marganiec, J.; Martínez, T.; Massimi, C.; Mastinu, P.; Mastromarco, M.; Mazzone, A.; Mendoza, E.; Milazzo, P. M.; Mingrone, F.; Mirea, M.; Montesano, S.; Nolte, R.; Oprea, A.; Pappalardo, A.; Patronis, N.; Pavlik, A.; Perkowski, J.; Piscopo, M.; Plompen, A.; Porras, I.; Praena, J.; Quesada, J.; Rajeev, K.; Rauscher, T.; Reifarth, R.; Riego-Perez, A.; Rout, P.; Rubbia, C.; Ryan, J.; Sabate-Gilarte, M.; Saxena, A.; Schillebeeckx, P.; Schmidt, S.; Sedyshev, P.; Smith, A. G.; Stamatopoulos, A.; Tagliente, G.; Tain, J. L.; Tarifeño-Saldivia, A.; Tassan-Got, L.; Tsinganis, A.; Valenta, S.; Vannini, G.; Variale, V.; Vaz, P.; Ventura, A.; Vlachoudis, V.; Vlastou, R.; Vollaire, J.; Wallner, A.; Warren, S.; Weigand, M.; Weiß, C.; Wolf, C.; Woods, P. J.; Wright, T.; Žugec, P.

    2016-01-01

    The energy-dependent cross section of the 7Be(n,alpha)4He reaction, of interest for the so-called Cosmological Lithium Problem in Big Bang Nucleosynthesis, has been measured for the first time from 10 meV to 10 keV neutron energy. The challenges posed by the short half-life of 7Be and by the low reaction cross section have been overcome at n_TOF thanks to an unprecedented combination of the extremely high luminosity and good resolution of the neutron beam in the new experimental area (EAR2) of the n_TOF facility at CERN, the availability of a sufficient amount of chemically pure 7Be, and a specifically designed experimental setup. Coincidences between the two alpha-particles have been recorded in two Si-7Be-Si arrays placed directly in the neutron beam. The present results are consistent, at thermal neutron energy, with the only previous measurement performed in the 60's at a nuclear reactor. The energy dependence here reported clearly indicates the inadequacy of the cross section estimates currently used in ...

  14. About the reactions sup 3 H(alpha,gamma) sup 7 Li and sup 3 He(alpha,gamma) sup 7 Be

    CERN Document Server

    Loeffler, W

    1993-01-01

    In this article the current experimental and theoretical status of the radiative alpha capture reactions sup 3 H(alpha,gamma) sup 7 Li and sup 3 He(alpha,gamma) sup 7 Be and their relations to primordial nucleosynthesis and the solar neutrino problem are reviewed. (author)

  15. Asymptotic normalization coefficients (nuclear vertex constants) for the p+7Be→8B and the 7Be(p, γ)8B astrophysical S-factors at solar energies

    International Nuclear Information System (INIS)

    Igamov, S.B.; Yarmukhamedov, R.

    2007-01-01

    Full text: The 7 Be(p,γ) 8 B reaction rate given by in terms of the zero-energy astrophysical S-factor S(0) is one of the main input data in the solar neutrino problem because the high energy neutrinos are produced via the decay 8 B→ 7 Be+e + + n e . This quantity is determined by both extrapolating the measured absolute cross sections σexp (E) (or equivalently its experimental S-factors S exp (E) ) to solar energies (≅ 25 keV) and the theoretical predictions. Despite the steady and impressive progress in our understanding of this reaction have been made in last years in measurements S exp (E) at extremely low energies and the theoretical predictions S(E) at solar energies (E≤25 keV), ambiguities (up to about 35%) associated with prediction for S(0) however still exist, and it may considerably influence the predictions of the standard solar model. In this work the modified two - body potential approach is applied for a new analysis of the highly precise experimental astrophysical S-factors for the direct capture 7 Be(p, γ) 8 B reaction at E≤400 keV and 1000≤E≤1200 keV to obtain 'indirectly measured' values both of the asymptotic normalization coefficient (ANC) for the p+ 7 Be→ 8 B and of S(E) at E≤115 keV, including E=0. In this approach S(E) is expressed in the terms of ANC C Aα;lj 2 but not in the terms of the usual spectroscopic factor Z Aα;lj , which is related to the ANC C Aα;l. j as Z aα;lj =C Aα;lj 2 /b lj 2 , where b lj is the single-particle ANC for the wave function of the bound 8 B( 7 Be+p) state calculated within the shell model using the phenomenological Woods-Saxon potential with the geometric parameters (a radius r o and a diffuseness a). The approach allows one to remove the model dependence of the calculated direct on S(E) on the geometric parameters r o and a both for the two-body bound ( 7 Be+p) state and the p 7 Be- scattering state in minimum. The analysis of the experimental S exp (E) is performed by verifying values of

  16. Analysis of the 7Be (P, γ) 8B reaction at extremely low energies within the modified two-body potential approach

    International Nuclear Information System (INIS)

    Sanetullaev, A.; Igamov, S.B.; Yarmukhamedov, R.

    2004-01-01

    Full text: Obtaining the extremely low energy cross sections for the reaction 7 Be(p,γ ) 8 B is of great interest for a reliable estimation of the rate of this reaction, which is crucial for an accurate determination of the solar neutrino flux. At present, in current literature, there is a rather wide spread in estimation of this rate (see, for instance, Ref. [1] and references therein). In this work, the modified two-body potential approach for analysis of the astrophysical S- factor S(E) for the peripheral direct radiative capture 7 Be(p,γ ) 8 B reaction of astrophysical interest is applied, in which the additional conditions of verification of the peripheral character of the reaction under consideration are formulated. The method involves the information on the asymptotic normalization coefficient (ANC) for the virtual decay 8 B → 7 Be+p and allows one to exclude the model dependence of the calculated direct astrophysical S-factor S(E) on the geometric parameters (radius r 0 and diffuseness a) of the adopted Woods-Saxon potential, which is usually used for calculations both for the two-body ( 7 Be+p)-bound state and for the 7 Be p -scattering state. The rather precise experimental astrophysical S-factor, S exp (E), in the energy range 100 7 Be(p,γ ) 8 B reaction, measured recently by the authors of Ref. [1] is used for the analysis. It is demonstrated that at extremely low energies this reaction is strongly peripheral and the measured S exp (E) can be used as an independent source of getting the information about the ANC. The new information about values of the ANC is obtained with an estimation of the weighted mean errors for them, which involves both the experimental errors of the S exp (E), and uncertainty of the method not exceeding 4%. The extracted value of the ANC is equal to C 2 =C 2 1/2 +C 2 3/2 =5.68± 0.15 fm -1 , where the indices show the value total angular momentum of the proton in the (p+ 7 Be)-bound state of 8 B. It was also demonstrated

  17. Cosmogenic radionuclides in the environment: {sup 32}Si in precipitation samples from the Jungfraujoch, production cross sections of {sup 36}Cl in Argon and modeling of the atmospheric {sup 36}Cl production

    Energy Technology Data Exchange (ETDEWEB)

    Parrat, Y. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-06-01

    The concentrations of the cosmogenic radionuclide {sup 32}Si were measured in four fresh snow samples from the Jungfraujoch in the Swiss Alps (3450 m asl.) to study the feasibility of measuring this potential dating nuclide with Accelerator Mass Spectrometry. This technique could reduce drastically the amount of material needed for measurements of {sup 32}Si concentrations in environmental samples in contrast to conventional radiometric detection. The measured {sup 32}Si concentrations in the snow samples were between 1.84 and 6.28 {mu}Bql{sup -1}. These values agree with other measurements of precipitation samples. The measured {sup 32}Si/Si{sub tot} ratios ranged from 2.5.10{sup -17} to 2.3.10{sup -15} and were thus below the present detection limit of about 10{sup -14}, showing that at present it is not possible to carry out AMS measurements of {sup 32}Si in precipitation samples. For the first time, experimental cross sections of the reaction {sup 40}Ar(p,X){sup 36}Cl have been determined for the proton energy range 16-590 MeV. These cross sections were measured using a gas target, a novel method which was tested successfully by irradiating nitrogen targets to confirm literature values of the N(p,X){sup 7}Be and N(p,X){sup 10}Be cross sections. In fact, good agreement was found between the obtained cross sections with those using solid targets. Production of several radionuclides in the reaction of proton with nickel were also measured. Comparison of these cross sections with literature data proved that the proton flux measurements carried out with ionization chambers were very accurate. The excitation function of the reaction {sup 40}Ar(p,X){sup 36}Cl exhibits two maxima at proton energies of 20 MeV for the (p,{alpha}n)reaction and 95 MeV for the (p,2p3n) reaction, with maximum cross sections of 105 mb and 53 mb, respectively. (author) figs., tabs., refs.

  18. Review and Discussion on the Key Assumptions and Challenges Surrounding the Use of {sup 7}Be as a Soil and Sediment Tracer

    Energy Technology Data Exchange (ETDEWEB)

    Mabit, L. [Soil and Water Management and Crop Nutrition Laboratory, IAEA (Austria); Taylor, A.; Blake, W. H. [School of Geography, Earth and Environmental Sciences, Plymouth University (United Kingdom); Smith, H. G. [School of Environmental Sciences, University of Liverpool (United Kingdom); Keith-Roach, M. J. [Kemakta Konsult, Stockholm (Sweden)

    2014-01-15

    Full text: The assumptions and challenges surrounding the use of {sup 7}Be to investigate soil and sediment in river basins have recently been reviewed (Taylor et al., 2013) to support the Coordinated Research Project D1.20.11 on Integrated Isotopic Approaches for an Area Wide Precision Conservation to Control the Impacts of Agricultural Practices on Land Degradation and Soil Erosion. This paper analyses the assumptions made in the context of hillslope erosion studies and additional implications for the use of {sup 7}Be as a tracer at a catchment-scale. A key assumption in hillslope erosion studies is that {sup 7}Be fallout is spatially uniform for a typical field or location. It is also important to assume that rainfall received prior to a study event is non-eroding to maintain a uniform inventory and enable estimates of soil redistribution to be attributed to a particular event. This requirement is well recognised by researchers in this field and these conditions have been met in studies shown in the literature. Little attention, however, has been given to the effects of other factors (e.g. atmospheric processes affecting the rainfall field across a site, topographic factors including the influence of vegetation cover), which could influence the uniformity of fallout and therefore the spatial variability of the {sup 7}Be inventory. Assumptions of spatially uniform fallout at the microscale has not been adequately supported by previous research. Studies demonstrated for example the variability in raindrop size distribution across short distances (i.e. 250 m). These factors are, however, likely to translate into minimal gradients in {sup 7}Be inventories and it is more likely that factors affecting the direct transfer of {sup 7}Be to soil, such as rain shadowing (by e.g. vegetation and topography) and interception by vegetation, will have a greater influence on spatial uniformity. These factors could present a fundamental challenge to the application of {sup 7}Be

  19. Experimental setup and procedure for the measurement of the 7Be(n,p)7Li reaction at n_TOF

    Science.gov (United States)

    Barbagallo, M.; Andrzejewski, J.; Mastromarco, M.; Perkowski, J.; Damone, L. A.; Gawlik, A.; Cosentino, L.; Finocchiaro, P.; Maugeri, E. A.; Mazzone, A.; Dressler, R.; Heinitz, S.; Kivel, N.; Schumann, D.; Colonna, N.; Aberle, O.; Amaducci, S.; Audouin, L.; Bacak, M.; Balibrea, J.; Bečvář, F.; Bellia, G.; Berthoumieux, E.; Billowes, J.; Bosnar, D.; Brown, A.; Caamaño, M.; Calviño, F.; Calviani, M.; Cano-Ott, D.; Cardella, R.; Casanovas, A.; Cerutti, F.; Chen, Y. H.; Chiaveri, E.; Cortés, G.; Cortés-Giraldo, M. A.; Cristallo, S.; Diakaki, M.; Dietz, M.; Domingo-Pardo, C.; Dupont, E.; Durán, I.; Fernández-Domínguez, B.; Ferrari, A.; Ferreira, P.; Furman, V.; Göbel, K.; García, A. R.; Gilardoni, S.; Glodariu, T.; Gonçalves, I. F.; González-Romero, E.; Griesmayer, E.; Guerrero, C.; Gunsing, F.; Harada, H.; Heyse, J.; Jenkins, D. G.; Jericha, E.; Johnston, K.; Käppeler, F.; Kadi, Y.; Kalamara, A.; Kavrigin, P.; Kimura, A.; Kokkoris, M.; Krtička, M.; Kurtulgil, D.; Leal-Cidoncha, E.; Lederer, C.; Leeb, H.; Lerendegui-Marco, J.; Lo Meo, S.; Lonsdale, S. J.; Macina, D.; Manna, A.; Marganiec, J.; Martínez, T.; Martins-Correia, J. G.; Masi, A.; Massimi, C.; Mastinu, P.; Mendoza, E.; Mengoni, A.; Milazzo, P. M.; Mingrone, F.; Musumarra, A.; Negret, A.; Nolte, R.; Oprea, A.; Pappalardo, A. D.; Patronis, N.; Pavlik, A.; Piscopo, M.; Porras, I.; Praena, J.; Quesada, J. M.; Radeck, D.; Rauscher, T.; Reifarth, R.; Robles, M. S.; Rubbia, C.; Ryan, J. A.; Sabaté-Gilarte, M.; Saxena, A.; Schell, J.; Schillebeeckx, P.; Sedyshev, P.; Smith, A. G.; Sosnin, N. V.; Stamatopoulos, A.; Tagliente, G.; Tain, J. L.; Tarifeño-Saldivia, A.; Tassan-Got, L.; Valenta, S.; Vannini, G.; Variale, V.; Vaz, P.; Ventura, A.; Vlachoudis, V.; Vlastou, R.; Wallner, A.; Warren, S.; Weiss, C.; Woods, P. J.; Wright, T.; Žugec, P.

    2018-04-01

    Following the completion of the second neutron beam line and the related experimental area (EAR2) at the n_TOF spallation neutron source at CERN, several experiments were planned and performed. The high instantaneous neutron flux available in EAR2 allows to investigate neutron induced reactions with charged particles in the exit channel even employing targets made out of small amounts of short-lived radioactive isotopes. After the successful measurement of the 7Be(n, α) α cross section, the 7Be(n,p)7Li reaction was studied in order to provide still missing cross section data of relevance for Big Bang Nucleosynthesis (BBN), in an attempt to find a solution to the cosmological Lithium abundance problem. This paper describes the experimental setup employed in such a measurement and its characterization.

  20. Aerosol Characterization at the WMO-GAW Station of Mt. Cimone (2165 m a.s.l.) by 7Be, 210Pb and PM10

    International Nuclear Information System (INIS)

    Tositti, Laura; Brattich, Erika; Cinelli, Giorgia; Cristofanelli, Paolo; Bonasoni, Paolo

    2011-01-01

    The importance of environmental radionuclides in the study of atmosphere and climate dynamics has long been recognized in the course of the last decades. The radiotracer method provides a powerful tool for the basic characterization of transfer and transformation mechanisms occurring both at local and large scale. For this reason several radionuclides, namely 7 Be, 210 Pb, 222 Rn and others are included among the key atmospheric components that are routinely monitored within the WMO-GAW network. In this work we will describe the long term monitoring activity of 7 Be, 210 Pb in the PM 10 fraction at Mt. Cimone station, a global WMO-GAW station in the Northern Italian Apennines hosting a complex activity of atmospheric research. Investigations in progress is aimed at characterizing the phenomenologies of ozone as well as of mineral dust incursions, two parameters of outstanding climatological relevance by means of several statistical methods including: time series analysis, multivariate analysis and source apportionment techniques

  1. Producing cement

    Energy Technology Data Exchange (ETDEWEB)

    Stone, E G

    1923-09-12

    A process and apparatus are described for producing Portland cement in which pulverized shale is successively heated in a series of inclined rotary retorts having internal stirrers and oil gas outlets, which are connected to condensers. The partially treated shale is removed from the lowermost retort by a conveyor, then fed separately or conjointly into pipes and thence into a number of vertically disposed retorts. Each of these retorts may be fitted interiorly with vertical arranged conveyors which elevate the shale and discharge it over a lip, from whence it falls to the bottom of the retorts. The lower end of each casing is furnished with an adjustable discharge door through which the spent shale is fed to a hopper, thence into separate trucks. The oil gases generated in the retorts are exhausted through pipes to condensers. The spent shale is conveyed to a bin and mixed while hot with ground limestone. The admixed materials are then ground and fed to a rotary kiln which is fired by the incondensible gases derived from the oil gases obtained in the previous retorting of the shale. The calcined materials are then delivered from the rotary kiln to rotary coolers. The waste gases from the kiln are utilized for heating the retorts in which the ground shale is heated for the purpose of extracting therefrom the contained hydrocarbon oils and gases.

  2. Activity concentrations of /sup 226/Ra, /sup 228/Ra, /sup 210/Pb, /sup 40/K and /sup 7/Be and their temporal variations in surface air

    Energy Technology Data Exchange (ETDEWEB)

    Hoetzl, H.; Winkler, R.

    1987-01-01

    Activity concentrations of the long-lived natural radionuclides /sup 226/Ra, /sup 228/Ra, /sup 210/Pb, /sup 40/K and of /sup 7/Be in surface air were measured twice monthly at a semi-rural location 10 km north of Munich (FRG) for at least three years. For the time interval 1983-1985, all values were found to be distributed log-normally, with geometric means (in ..mu..Bq m-./sup 3/) of 1.2 for /sup 226/Ra, 0.5 for /sup 228/Ra, 580 for /sup 210/Pb, 12 for /sup 40/K and 3500 for /sup 7/Be. Reflecting their common origin, the activity concentrations of /sup 226/Ra and /sup 40/K are correlated with surface air dust concentrations (geometric mean 59 ..mu..g m/sup -3/). Seasonal variations of /sup 210/Pb and /sup 7/Be air activity concentrations are established for the time interval 1978-1985.. The contribution of local soil activity to the air activity concentrations of these radionuclides and of natural uranium is discussed. Resuspension factors are found to be of the order of 10/sup -9/ m/sup -1/.

  3. Cosmogenic 10Be Depth Profile in top 560 m of West Antarctic Ice Sheet Divide Ice Core

    Science.gov (United States)

    Welten, K. C.; Woodruff, T. E.; Caffee, M. W.; Edwards, R.; McConnell, J. R.; Bisiaux, M. M.; Nishiizumi, K.

    2009-12-01

    Concentrations of cosmogenic 10Be in polar ice samples are a function of variations in solar activity, geomagnetic field strength, atmospheric mixing and annual snow accumulation rates. The 10Be depth profile in ice cores also provides independent chronological markers to tie Antarctic to Greenland ice cores and to tie Holocene ice cores to the 14C dendrochronology record. We measured 10Be concentrations in 187 samples from depths of 0-560 m of the main WAIS Divide core, WDC06A. The ice samples are typically 1-2 kg and represent 2-4 m of ice, equivalent to an average temporal resolution of ~12 years, based on the preliminary age-depth scale proposed for the WDC core, (McConnell et al., in prep). Be, Al and Cl were separated using ion exchange chromatography techniques and the 10Be concentrations were measured by accelerator mass spectrometry (AMS) at PRIME lab. The 10Be concentrations range from 8.1 to 19.1 x 10^3 at/g, yielding an average of (13.1±2.1) x 10^3 at/g. Adopting an average snow accumulation rate of 20.9 cm weq/yr, as derived from the age-depth scale, this value corresponds to an average 10Be flux of (2.7±0.5) x 10^5 atoms/yr/cm2. This flux is similar to that of the Holocene part of the Siple Dome (Nishiizumi and Finkel, 2007) and Dome Fuji (Horiuchi et al. 2008) ice cores, but ~30% lower than the value of 4.0 x 10^5 atoms/yr/cm2 for GISP2 (Finkel and Nishiizumi, 1997). The periods of low solar activity, known as Oort, Wolf, Spörer, Maunder and Dalton minima, show ~20% higher 10Be concentrations/fluxes than the periods of average solar activity in the last millennium. The maximum 10Be fluxes during some of these periods of low solar activity are up to ~50% higher than average 10Be fluxes, as seen in other polar ice cores, which makes these peaks suitable as chronologic markers. We will compare the 10Be record in the WAIS Divide ice core with that in other Antarctic as well as Greenland ice cores and with the 14C treering record. Acknowledgment. This

  4. Erosion patterns produced by the paleo Haizishan ice cap, SE Tibetan Plateau

    Science.gov (United States)

    Fu, P.; Stroeven, A. P.; Harbor, J.; Hättestrand, C.; Heyman, J.; Caffee, M. W.

    2017-12-01

    Erosion is a primary driver of landscape evolution, topographic relief production, geochemical cycles, and climate change. Combining in situ 10Be and 26Al exposure age dating, geomorphological mapping, and field investigations, we examine glacial erosion patterns of the almost 4,000 km2 paleo Haizishan ice cap on the southeastern Tibetan Plateau. Our results show that ice caps on the low relief Haizishan Plateau produced a zonal pattern of landscape modification. In locations where apparent exposure ages on bedrock are consistent with the last deglaciation, complete resetting of the cosmogenic exposure age clock indicates glacial erosion of at least a few meters. However, older apparent exposure ages on bedrock in areas known to have been covered by the paleo ice cap during the Last Glacial Maximum indicate inheritance and thus limited glacial erosion. Inferred surface exposure ages from cosmogenic depth profiles through two saprolites vary from resetting and thus saprolite profile truncation to nuclide inheritance indicating limited erosion. Finally, significant nuclide inheritance in river sand samples from basins on the scoured plateau surface also indicate limited glacial erosion during the last glaciation. Hence, for the first time, our study shows clear evidence of preservation under non-erosive ice on the Tibetan Plateau. As patterns of glacial erosion intensity are largely driven by the basal thermal regime, our results confirm earlier inferences from geomorphology for a concentric basal thermal pattern for the paleo Haizishan ice cap during the LGM.

  5. Reconstruction of the Exposure Histories of 20 Allan Hills Ordinary Chondrites on the Basis of Cosmogenic 10Be, 26Al, Noble Gases, and Cosmic Ray Tracks

    Science.gov (United States)

    Neupert, U.; Knauer, M.; Michel, R.; Loeken, Th.; Schultz, L.; Dittrich-Hannen, B.; Suter, M.; Kubik, P. W.; Metzler, K.; Romstedt, J.

    1995-09-01

    Twenty ordinary chondrites from the 1988/89 meteorite search (ALH 88004, 88008, 88010, 88011, 88013, 88016 to 88021, 88026 to 88031, 88033, 88039, 88042) [1,2] were investigated for 10Be and 26Al, and for He, Ne and Ar by accelerator and rare gas mass spectrometry, respectively. Cosmic ray tracks were measured in samples of ALH 88019. Using theoretical production rates calculated by a physical model [3] the experimental data are interpreted with respect to the reconstruction of the preatmospheric exposure conditions and exposure histories of the meteoroids. Ordinary chondrites are particularly well suited to exemplify the capabilities of an interpretation of many cosmogenic nuclides measured in one sample. Model calculations of GCR production rates were performed for 10Be, 26Al, 3He, 21Ne, 22Ne and 38Ar as reported elsewhere [4,5]. For all meteorites, except for ALH 88019, the cosmogenic nuclide data can be explained by simple one stage exposure histories between 3 Ma and 44 Ma in meteoroids with radii between 5 cm and 85 cm. Exposure ages were derived from cosmogenic 3He, 21Ne and 38Ar on the basis of the theoretical production rates as function of3He/21Ne and 22Ne/21Ne as well as on the empirical ones proposed by Eugster [6]. The average ratios of exposure ages determined from theoretical production rates to those calculated according to Eugster [6] were 1.08+/-0.11, 1.11+/-0.25 and 1.12+/-0.17 in case of 3He, 21Ne and 38Ar, respectively. Repeated measurements of 10Be and 26Al in ALH 88019 resulted in 10.4+/-1.3 dpm/kg and 5.6+/-0.5 dpm/kg, respectively. But, the cosmogenic rare gas concentrations point to a (single stage) exposure age of 39 Ma in a meteoroid. This is in accordance with a measured cosmic ray track density in olivine of 2.8 * 10^6 cm^-2. The samples are from depths betwen 3 cm and 8 cm. Based on the track data we obtain a minimum meteoroid radius of 8 cm. The low 10Be and 26Al cannot be explained by a one stage exposure history and a long

  6. Glacial evolution in King George and Livingston Islands (Antarctica) since the Last Glacial Maximum based on cosmogenic nuclide dating and glacier surface reconstruction - CRONOANTAR project

    Science.gov (United States)

    Ruiz Fernández, Jesús; Oliva, Marc; Fernández Menéndez, Susana del Carmen; García Hernández, Cristina; Menéndez Duarte, Rosa Ana; Pellitero Ondicol, Ramón; Pérez Alberti, Augusto; Schimmelpfennig, Irene

    2017-04-01

    CRONOANTAR brings together researchers from Spain, Portugal, France and United Kingdom with the objective of spatially and temporally reconstruct the deglaciation process at the two largest islands in the South Shetlands Archipelago (Maritime Antarctica), since the Global Last Glacial Maximum. Glacier retreat in polar areas has major implications at a local, regional and even planetary scale. Global average sea level rise is the most obvious and socio-economically relevant, but there are others such as the arrival of new fauna to deglaciated areas, plant colonisation or permafrost formation and degradation. This project will study the ice-free areas in Byers and Hurd peninsulas (Livingston Island) and Fildes and Potter peninsulas (King George Island). Ice-cap glacier retreat chronology will be revealed by the use of cosmogenic isotopes (mainly 36Cl) on glacially originated sedimentary and erosive records. Cosmogenic dating will be complemented by other dating methods (C14 and OSL), which will permit the validation of these methods in regions with cold-based glaciers. Given the geomorphological evidences and the obtained ages, a deglaciation calendar will be proposed and we will use a GIS methodology to reconstruct the glacier extent and the ice thickness. The results emerging from this project will allow to assess whether the high glacier retreat rates observed during the last decades were registered in the past, or if they are conversely the consequence (and evidence) of the Global Change in Antarctica. Acknowledgements This work has been funded by the Spanish Ministry of Economy, Industry and Competitiveness (Reference: CTM2016-77878-P).

  7. Influence of long-range atmospheric transport pathways and climate teleconnection patterns on the variability of surface 210Pb and 7Be concentrations in southwestern Europe.

    Science.gov (United States)

    Grossi, C; Ballester, J; Serrano, I; Galmarini, S; Camacho, A; Curcoll, R; Morguí, J A; Rodò, X; Duch, M A

    2016-12-01

    The variability of the atmospheric concentration of the 7 Be and 210 Pb radionuclides is strongly linked to the origin of air masses, the strength of their sources and the processes of wet and dry deposition. It has been shown how these processes and their variability are strongly affected by climate change. Thus, a deeper knowledge of the relationship between the atmospheric radionuclides variability measured close to the ground and these atmospheric processes could help in the analysis of climate scenarios. In the present study, we analyze the atmospheric variability of a 14-year time series of 7 Be and 210 Pb in a Mediterranean coastal city using a synergy of different indicators and tools such as: the local meteorological conditions, global and regional climate indexes and a lagrangian atmospheric transport model. We particularly focus on the relationships between the main pathways of air masses and sun spots occurrence, the variability of the local relative humidity and temperature conditions, and the main modes of regional climate variability, such as the North Atlantic Oscillation (NAO) and the Western Mediterranean Oscillation (WeMO). The variability of the observed atmospheric concentrations of both 7 Be and 210 Pb radionuclides was found to be mainly positively associated to the local climate conditions of temperature and to the pathways of air masses arriving at the station. Measured radionuclide concentrations significantly increase when air masses travel at low tropospheric levels from central Europe and the western part of the Iberian Peninsula, while low concentrations are associated with westerly air masses. We found a significant negative correlation between the WeMO index and the atmospheric variability of both radionuclides and no significant association was observed for the NAO index. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Astrophysical 3He(α ,γ )7Be and 3H(α ,γ )7Li direct capture reactions in a potential-model approach

    Science.gov (United States)

    Tursunov, E. M.; Turakulov, S. A.; Kadyrov, A. S.

    2018-03-01

    The astrophysical 3He(α ,γ )7Be and 3H(α ,γ )7Li direct capture processes are studied in the framework of the two-body model with potentials of a simple Gaussian form, which describe correctly the phase shifts in the s , p , d , and f waves, as well as the binding energy and the asymptotic normalization constant of the ground p3 /2 and the first excited p1 /2 bound states. It is shown that the E 1 transition from the initial s wave to the final p waves is strongly dominant in both capture reactions. On this basis the s -wave potential parameters are adjusted to reproduce the new data of the LUNA Collaboration around 100 keV and the newest data at the Gamov peak estimated with the help of the observed neutrino fluxes from the sun, S34(23-5+6keV ) =0.548 ±0.054 keV b for the astrophysical S factor of the capture process 3He(α ,γ )7Be . The resulting model describes well the astrophysical S factor in the low-energy big-bang nucleosynthesis region of 180-400 keV; however, it has a tendency to underestimate the data above 0.5 MeV. The energy dependence of the S factor is mostly consistent with the data and the results of the no-core shell model with continuum, but substantially different from the fermionic molecular dynamics model predictions. Two-body potentials, adjusted for the properties of the 7Be nucleus, 3He+α elastic scattering data, and the astrophysical S factor of the 3He(α ,γ )7Be direct capture reaction, are able to reproduce the properties of the 7Li nucleus, the binding energies of the ground 3 /2- and first excited 1 /2- states, and phase shifts of the 3H+α elastic scattering in partial waves. Most importantly, these potential models can successfully describe both absolute value and energy dependence of the existing experimental data for the mirror astrophysical 3H(α ,γ )7Li capture reaction without any additional adjustment of the parameters.

  9. Measurement of concentrations of 7Be, 90Sr, 134,137Cs, 210Pb and 226Ra in the tropospheric and lower stratospheric air in 1997 and 1998

    International Nuclear Information System (INIS)

    Kownacka, L.; Jaworowski, Z.; Zajac, B.

    1999-01-01

    In this report the results of the vertical distribution of atmospheric particulates concentrations of fission products and natural radionuclides 7 Be, 210 Pb, 226 Ra are presented for 1997 and 1998. The measurements have been carried out over north-eastern part of Poland. The samples of aerosols were collected with airplane samplers at 1, 3, 6, 9, 12 and 15 km altitudes, and with a stationary sampler near the ground level. Concentrations of radiocesium in both stratospheric and ground level air were in 1997 and 1998 lower then before the Chernobyl accident. In the troposphere in 1998 concentration increased by a factor of 6 due to a nuclear incident in Spain. (author)

  10. Transfer vs. Breakup in the interaction of the 7Be Radioactive Ion Beam with a 58Ni target at Coulomb barrier energies

    Directory of Open Access Journals (Sweden)

    Mazzocco M.

    2014-03-01

    Full Text Available We measured for the first time 7Be elastically scattered nuclei as well as 3,4He reaction products from a 58Ni target at 22.3 MeV beam energy. The data were analyzed within the optical model formalism to extract the total reaction cross section. Extensive kinematical, Distorted Wave Born Approximation (DWBAand Continuum Discretized Coupled Channel (CDCC calculations were performed to investigate the 3,4He originating mechanisms and the interplay between different reaction channels.

  11. Experimental setup and procedure for the measurement of the {sup 7}Be(n,α)α reaction at n-TOF

    Energy Technology Data Exchange (ETDEWEB)

    Cosentino, L. [INFN Laboratori Nazionali del Sud, Catania (Italy); Musumarra, A. [INFN Laboratori Nazionali del Sud, Catania (Italy); Dipartimento di Fisica e Astronomia DFA, Università di Catania (Italy); Barbagallo, M. [INFN Sezione di Bari (Italy); Pappalardo, A. [INFN Laboratori Nazionali del Sud, Catania (Italy); Colonna, N.; Damone, L. [INFN Sezione di Bari (Italy); Piscopo, M. [INFN Laboratori Nazionali del Sud, Catania (Italy); Finocchiaro, P., E-mail: FINOCCHIARO@LNS.INFN.IT [INFN Laboratori Nazionali del Sud, Catania (Italy); Maugeri, E.; Heinitz, S.; Schumann, D.; Dressler, R.; Kivel, N. [Paul Scherrer Institut, Nuclear Energy and Safety Research Department, 5232 Villigen (Switzerland); Aberle, O. [CERN, Geneva (Switzerland); Andrzejewski, J. [Uniwersytet Łódzki, Lodz (Poland); Audouin, L. [Institut de Physique Nucléaire, CNRS-IN2P3, Univ. Paris-Sud, Université Paris-Saclay, 91406 Orsay Cedex (France); Ayranov, M. [European Commission, DG-Energy (Luxembourg); Bacak, M. [Atominstitut der Österreichischen Universitäten, Technische Universität Wien (Austria); Barros, S. [C2TN-Instituto Superior Tecníco, Universidade de Lisboa (Portugal); Balibrea-Correa, J. [Centro de Investigaciones Energeticas Medioambientales y Tecnológicas (CIEMAT), Madrid (Spain); and others

    2016-09-11

    The newly built second experimental area EAR2 of the n-TOF spallation neutron source at CERN allows to perform (n, charged particles) experiments on short-lived highly radioactive targets. This paper describes a detection apparatus and the experimental procedure for the determination of the cross-section of the {sup 7}Be(n,α)α reaction, which represents one of the focal points toward the solution of the cosmological Lithium abundance problem, and whose only measurement, at thermal energy, dates back to 1963. The apparently unsurmountable experimental difficulties stemming from the huge {sup 7}Be γ-activity, along with the lack of a suitable neutron beam facility, had so far prevented further measurements. The detection system is subject to considerable radiation damage, but is capable of disentangling the rare reaction signals from the very high background. This newly developed setup could likely be useful also to study other challenging reactions requiring the detectors to be installed directly in the neutron beam.

  12. The solar Lithium problem: is the explanation due solely to mixing or also to the e-capture decay rate of 7Be?

    Science.gov (United States)

    Vescovi, Diego; Busso, Maurizio; Palmerini, Sara; Trippella, Oscar

    2018-01-01

    The nucleosynthesis of 7Li is one of the most crucial problems in nuclear as- trophysics, as its observations in several sites are hard to be explained. Concerning the Sun, the most common interpretations of the low Li abundance invoke either burning in early stages or non-convective mixing below the envelope. Here we apply a diffusive mechanism of mixing, together with a recent estimate of the rate for e-captures on 7Be, to establish whether the solar Li destruction should be attributed to purely pre-Main Se- quence (MS) nuclear processes or if the coupling of mixing and nucleosynthesis on the MS can account for it. Our preliminary results indicate that, whether Li survives the pre- MS phase, the changes of the 7Be e--capture rate do not affect its production/destruction. The low Li abundance should then depend only on diffusion processes from the bottom of the convective envelope to the lowerlying tachocline zone. We suggest that, if diffusive processes occurred over the age of the Sun, they required diffusive mass transfers of a few 10-13 M⊙/yr to explain the Li drop. This is a high estimate: future works will tell us if it is realistic or not. In this second case, pre-MS burning would remain the only alternative.

  13. Cosmic-ray-produced stable nuclides: various production rates and their implications

    International Nuclear Information System (INIS)

    Reedy, R.C.

    1981-01-01

    The rates for a number of reactions producing certain stable nuclides, such as 3 He and 4 He, and fission in the moon are calculated for galactic-cosmic-ray particles and for solar protons. Solar-proton-induced reactions with bromine usually are not an important source of cosmogenic Kr isotopes. The 130 Ba(n,p) reaction cannot account for the undercalculation of 130 Xe production rates. Calculated production rates of 15 N, 13 C, and 2 H agree fairly well with rates inferred from measured excesses of these isotopes in samples with long exposure ages. Cosmic-ray-induced fission of U and Th can produce significant amounts of fission tracks and of 86 Kr, 134 Xe, and 136 Xe, especially in samples with long exposures to cosmic-ray particles

  14. $sup 155$Eu, $sup 144$Ce, $sup 125$Sb, $sup 106$Ru, $sup 95$Zr, $sup 54$Mn, and $sup 7$Be in the reindeer lichen Cladonia alpestris: deposition, retention and internal distribution, 1961--1970

    Energy Technology Data Exchange (ETDEWEB)

    Mattsson, L J.S.

    1972-09-01

    The retention and distribution of the fallout radionuclides , /sup 106/ Ru, /sup 95/Zr, and /sup 54/Mn and the naturally occurring radionuclide /sup 7/Be were studied in undisturbed natural carpets of the lichen Cladonia alpesiris, a major component of the diet of reindeer in the Lake Rogen district in central Sweden during the period 1961 to 1970. The contents of the artificially produced radionuclides in the lichen-carpet reached their maxima in 1963 to 1966 and all showed high retention values. During the seven-year period of 1962 to 1968 the average absorbed dose in the gut of a reindeer was calculated to be about 3 rad due to the passage of the food alone. The dominating contributions (about 40%) came from /sup 144/Ce. (CH)

  15. Five-nucleon simultaneous and sequential transfer in the 12C(11B,6Li)17O and 12C(d,7Li)7Be reactions

    International Nuclear Information System (INIS)

    Jarczyk, L.; Kamys, B.; Kistryn, M.; Magiera, A.; Rudy, Z.; Strzal/kowski, A.; Barna, R.; DAmico, V.; De Pasquale, D.; Italiano, A.; Licandro, M.

    1996-01-01

    Measurements of the angular distributions of the 12 C( 11 B, 6 Li) 17 O reaction were performed at three energies of a 11 B beam: 28, 35, and 40 MeV. The results were analyzed in the frame of the exact finite range distorted wave Born approximation of the first and the second order assuming the simultaneous and sequential transfer of the neutron and the α particle. Such an analysis was also performed for previously measured angular distributions of the 12 C(d, 7 Li) 7 Be reaction at E lab = 78 MeV. In both reactions under investigation dominance was found of the simultaneous transfer of the α particle and the nucleon correlated to the 5 He ( 5 Li) cluster in the ground or the first excited state. copyright 1996 The American Physical Society

  16. Application Of 137Cs And 7Be To Assess The Effectiveness Of Soil Conservation Technologies In The Central Highlands Of Vietnam

    International Nuclear Information System (INIS)

    Phan Son Hai; Tran Dinh Khoa; Nguyen Dao; Nguyen Thi Mui; Tran Van Hoa; Trinh Cong Tu

    2008-01-01

    The combined use of 137 Cs and 7 Be for assessment of medium- and short-term soil erosion rates for sloping lands with and without soil conservation technologies in the Central Highlands of Vietnam has been carried out. For the 2.5 ha mulberry field with the slope gradient of about 15%, where green manure hedgerows have been utilized as a soil conservation measure for 22 years, about 54.6% of the area suffered from erosion with erosion rates varying from 0.6 to 70 t ha -1 y -1 (the average: 31 t ha -1 y -1 ), and deposition occurred for 45.4% of the area with the deposition rates ranging between 0.2 and 74 t ha-1 y-1 (the average: 36 t ha -1 y -1 ). The medium-term erosion rate at this field was 1.2 ± 0.6 t ha -1 y -1 , and short-term erosion rate was 1.5 ± 0.24 t ha -1 y -1 . Soil erosion was almost controlled by the shrubby hedgerows and the net erosion rate was reduced from 28 t ha -1 y -1 to 1.2 t ha -1 y -1 . 137 Cs and 7 Be were also used for assessment of soil erosion rates for two 0.5 ha coffee plots with the slope gradient of about 25%. For the plot without soil conservation, soil erosion occurred for all sampling points with medium-term erosion rates ranging between 1.2 t ha -1 y -1 and 35 t ha -1 y -1 (the average erosion rate was 22.7 ± 1.2 t ha -1 y -1 ). The short term soil erosion rate estimated by 7 Be technique in the year 2005 was 32.7 ± 6.1 t ha -1 y -1 for this plot. For the plot with the last five year presence of Vetiver strips, about 93% of the area suffered from medium term erosion with erosion rates varying from 3 t ha -1 y -1 to 33 t ha -1 y -1 (the mean is 22.2 t ha -1 y -1 ), and medium term deposition occurred for only 7% of the area with the deposition rates ranging between 1.3 and 1.4 t ha -1 y -1 , resulting in the net erosion rate of 20.4 ± 0.6 t ha -1 y -1 . The short term soil erosion rate at this plot estimated by 7 Be technique in the year 2005 was 2.3 t ha -1 y -1 . By using Vetiver strips as a soil conservation technology

  17. Optimization of a neutron production target based on the 7Li (p,n)7Be reaction with the Monte Carlo Method

    International Nuclear Information System (INIS)

    Burlon, Alejandro A.; Kreiner, Andres J.; Minsky, Daniel; Valda, Alejandro A.; Somacal, Hector R.

    2003-01-01

    In order to optimize a neutron production target for accelerator-based boron neutron capture therapy (AB-BNCT) a Monte Carlo Neutron and Photon (MCNP) investigation has been performed. Neutron fields from a LiF thick target (with both a D 2 O-graphite and a Al/AlF 3 -graphite moderator/reflector assembly) were evaluated along the centerline in a head phantom. The target neutron beam was simulated from the 7 Li(p,n) 7 Be nuclear reaction for 1.89, 2.0 and 2.3 MeV protons. The results show that it is more advantageous to irradiate the target with near resonance energy protons (2.3 MeV) because of the high neutron yield at this energy. On the other hand, the Al/AlF 3 -graphite exhibits a more efficient performance than D 2 O. (author)

  18. Importance of coccolithophore-associated organic biopolymers for fractionating particle-reactive radionuclides (234Th, 233Pa, 210Pb, 210Po, and 7Be) in the ocean

    Science.gov (United States)

    Lin, Peng; Xu, Chen; Zhang, Saijin; Sun, Luni; Schwehr, Kathleen A.; Bretherton, Laura; Quigg, Antonietta; Santschi, Peter H.

    2017-08-01

    Laboratory incubation experiments using the coccolithophore Emiliania huxleyi were conducted in the presence of 234Th, 233Pa, 210Pb, 210Po, and 7Be to differentiate radionuclide uptake to the CaCO3 coccosphere from coccolithophore-associated biopolymers. The coccosphere (biogenic calcite exterior and its associated biopolymers), extracellular (nonattached and attached exopolymeric substances), and intracellular (sodium-dodecyl-sulfate extractable and Fe-Mn-associated metabolites) fractions were obtained by sequentially extraction after E. huxleyi reached its stationary growth phase. Radionuclide partitioning and the composition of different organic compound classes, including proteins, total carbohydrates (TCHO), and uronic acids (URA), were assessed. 210Po was closely associated with the more hydrophobic biopolymers (high protein/TCHO ratio, e.g., in attached exopolymeric substances), while 234Th and 233Pa showed similar partitioning behavior with most activity being distributed in URA-enriched, nonattached exopolymeric substances and intracellular biopolymers. 234Th and 233Pa were nearly undetectable in the coccosphere, with a minor abundance of organic components in the associated biopolymers. These findings provide solid evidence that biogenic calcite is not the actual main carrier phase for Th and Pa isotopes in the ocean. In contrast, both 210Pb and 7Be were found to be mostly concentrated in the CaCO3 coccosphere, likely substituting for Ca2+ during coccolith formation. Our results demonstrate that even small cells (E. huxleyi) can play an important role in the scavenging and fractionation of radionuclides. Furthermore, the distinct partitioning behavior of radionuclides in diatoms (previous studies) and coccolithophores (present study) explains the difference in the scavenging of radionuclides between diatom- and coccolithophore-dominated marine environments.

  19. Use of fallout radionuclides ((7)Be, (210)Pb) to estimate resuspension of Escherichia coli from streambed sediments during floods in a tropical montane catchment.

    Science.gov (United States)

    Ribolzi, Olivier; Evrard, Olivier; Huon, Sylvain; Rochelle-Newall, Emma; Henri-des-Tureaux, Thierry; Silvera, Norbert; Thammahacksac, Chanthamousone; Sengtaheuanghoung, Oloth

    2016-02-01

    Consumption of water polluted by faecal contaminants is responsible for 2 million deaths annually, most of which occur in developing countries without adequate sanitation. In tropical aquatic systems, streambeds can be reservoirs of persistent pathogenic bacteria and high rainfall can lead to contaminated soils entering streams and to the resuspension of sediment-bound microbes in the streambed. Here, we present a novel method using fallout radionuclides ((7)Be and (210)Pbxs) to estimate the proportions of Escherichia coli, an indicator of faecal contamination, associated with recently eroded soil particles and with the resuspension of streambed sediments. We show that using these radionuclides and hydrograph separations we are able to characterize the proportion of particles originating from highly contaminated soils and that from the resuspension of particle-attached bacteria within the streambed. We also found that although overland flow represented just over one tenth of the total flood volume, it was responsible for more than two thirds of the downstream transfer of E. coli. We propose that data obtained using this method can be used to understand the dynamics of faecal indicator bacteria (FIB) in streams thereby providing information for adapted management plans that reduce the health risks to local populations. Graphical Abstract Graphical abstract showing (1) the main water flow processes (i.e. overland flow, groundwater return flow, blue arrows) and sediment flow components (i.e. resuspension and soil erosion, black arrows) during floods in the Houay Pano catchment; (2) the general principle of the method using fallout radionuclide markers (i.e. (7)Be and (210)Pbxs) to estimate E. coli load from the two main sources (i.e. streambed resuspension vs soil surface washoff); and 3) the main results obtained during the 15 May 2012 storm event (i.e. relative percentage contribution of each process to the total streamflow, values in parentheses).

  20. Effects of an energy broadened proton beam on the neutron distribution for the "7Li(p,n)"7Be reaction near threshold

    International Nuclear Information System (INIS)

    Shor, A.; Eisen, Y.; Berkovits, D.; Hirsh, T.; Feinberg, G.; Friedman, M.; Paul, M.; Krasa, A.; Giorginis, G.; Plompen, A.

    2011-01-01

    A common method for simulating the thermal neutron conditions in the stellar interior is based on the "7Li(p,n)"7Be reaction near threshold energy. Maxwellian-averaged neutron capture cross-sections of mean energy 25 keV, relevant to the s-process nucleosynthesis, are measured at existing Van-de-Graaff (VdG) proton accelerators. Soreq NRC Applied Research superconducting linear Accelerator Facility (SARAF) phase 1 is in its final stage of commissioning. Maxwellian averaged neutron capture cross-section measurements are planned to be conducted using a forced-flow closed-loop liquid-lithium target (LiLiT). The proton beam energy spread of RF linear accelerators, such as SARAF, is typically larger than the spread of proton beams of VdG accelerators. The energy spread of SARAF proton beam at 1912 keV is calculated to be of the order of 20-40 keV FWHM as compared to about 3 keV FWHM for VdG accelerators. For simulating the SARAF proton beam we performed an experiment at the IRMM-Geel VdG using a gold foil degrader positioned before the LiF target. This degrader shifts the mean proton energy to 1912 keV and it broadens the proton beam energy to values simulating the spread of the proton beam at SARAF. For calibrating the cross-sections we also performed a "7Li(p,n)"7Be experiment without the gold foil degrader at a proton energy of 1912 keV. The VdG was operated in a pulse mode and the neutron energies were determined by time-of-flight measurements using "6Li glass detectors. Detector efficiencies were obtained by Monte Carlo calculations. We present our study and compare the results for both narrow and broad energy proton beams. It is shown that the energy distribution for the broad-energy beam with a spread of 15 keV is similar to that of the distribution of the narrow energy beam and they peak nearly at the same energy. The broad-energy distribution has a tail extending to higher energies than that of the narrow-energy beam. It appears also that the neutron

  1. Investigating the temporal dynamics of suspended sediment during flood events with 7Be and 210Pbxs measurements in a drained lowland catchment

    Science.gov (United States)

    Le Gall, Marion; Evrard, Olivier; Foucher, Anthony; Laceby, J. Patrick; Salvador-Blanes, Sébastien; Manière, Louis; Lefèvre, Irène; Cerdan, Olivier; Ayrault, Sophie

    2017-02-01

    Soil erosion is recognized as one of the main processes of land degradation in agricultural areas. High suspended sediment loads, often generated from eroding agricultural landscapes, are known to degrade downstream environments. Accordingly, there is a need to understand soil erosion dynamics during flood events. Suspended sediment was therefore sampled in the river network and at tile drain outlets during five flood events in a lowland drained catchment in France. Source and sediment fallout radionuclide concentrations (7Be, 210Pbxs) were measured to quantify both the fraction of recently eroded particles transported during flood events and their residence time. Results indicate that the mean fraction of recently eroded sediment, estimated for the entire Louroux catchment, increased from 45 ± 20% to 80 ± 20% between December 2013 and February 2014, and from 65 ± 20% to 80 ± 20% in January 2016. These results demonstrate an initial flush of sediment previously accumulated in the river channel before the increasing supply of sediment recently eroded from the hillslopes during subsequent events. This research highlights the utility of coupling continuous river monitoring and fallout radionuclide measurements to increase our understanding of sediment dynamics and improve the management of soil and water resources in agricultural catchments.

  2. Astrophysical S-factor of the 32He(α,γ) 733 7Be reaction in the Big-Bang nucleosynthesis

    Science.gov (United States)

    Ghamary, Motahareh; Sadeghi, Hossein; Mohammadi, Saeed

    2018-05-01

    In the present work, we have studied the properties of the 23He(α , γ) 47Be reaction. The direct radiative capture nuclear reactions in the Big-Bang nucleosynthesis mainly, are done in the external areas of inter-nuclear interaction range and play an essential role in nuclear astrophysics. Among of these reactions, the 23He(α , γ) 47Be reaction with Q = 1.586 MeV is the main part of the Big-Bang nucleosynthesis chain reactions. This reaction can be used to understand the physical and chemical properties of the sun as well as can be justified the lake of the observed solar neutrino in the detector of the Earth. Since product neutrino fluxes are predicated in the center of the sun by the decay of 7Be and 8B, and almost are proportional to the astrophysical S-factor for the 23He(α , γ) 47Be reaction, S34. The 23He(α , γ) 47Be reaction is considered the key to solve the solar neutrino puzzle. Finally, we have astrophysical S-factor obtained for the ground S1,3/2-, first excited S1,1/2-and total S34 states by modern nucleon-nucleon two-body local potential models. We have also compared the obtained S-factor with experimental data and other theoretical works.

  3. Toward detection of supernova event near the earth based on high-resolution analysis of cosmogenic nuclide 10Be in marine sediments

    Science.gov (United States)

    Takiguchi, S.; Suganuma, Y.; Kataoka, R.; Yamaguchi, K. E.

    2017-12-01

    Cosmic rays react with substances in the Earth's atmosphere and form cosmogenic nuclides. The flux would abruptly increase with nearby supernova or terrestrial magnetic events such as reversal or excursion of terrestrial magnetism. The Earth must have been exposed to cosmic ray radiation for as long as 10 Ma, if any, by nearby supernova activities (Kataoka et al., 2014). Increased and prolonged activity of cosmic rays would affect Earth's climate through forming greenhouse gases and biosphere through damaging DNA. Therefore, interests have been growing as to whether and how past supernova events have ever left any fingerprints on them. However, detection of nearby supernova is still under debate (e.g., Knie et al., 2004) To detect long-term record of past supernova activities, we utilize cosmogenic nuclide 10Be because of its short residence time (1-2yr) in the atmosphere, simple transport process, and adequate half-life (1.36 kyr) which is nearly equivalent to the duration of present-day deep water circulation. Sediment samples collected from the equatorial western Pacific (706-825 kyr in age) were finely powdered and decomposed by mixed acids (HNO3, HF, and HClO4). Authigenic phase was also separated from bulk powders by leaching with a weak acid. Because quantitative separation of Be from samples is essential toward high-quality 10Be analysis, both Be-bearing fractions were applied to optimized anion exchange chromatography for Be separation, and Be abundance was measured by atomic absorption spectrometry. The 10Be abundance (10Be/9Be ratios) were measured by accelerator mass spectrometry. The authigenic phase showed temporal curve that is similar to that of bulk samples (Suganuma et al., 2012), reflecting the influence of relative paleo-intensity and utility of authigenic method. Increased data set in terms of sampling interval (density) and total age range would allow us to judge whether it could detect past supernova activities and how it appears when

  4. Cosmogenic 10Be ages from the Meirs and Garwood Valleys, Denton Hills, West Antarctica, suggest an absence in LGM Ice Sheet expansion.

    Science.gov (United States)

    Fink, David; Joy, Kurt; Storey, Bryan

    2014-05-01

    It has been hypothesised that during interglacials, thinning of the Ross Ice Shelf allowed a more open water environment with increased local precipitation. This resulted in outlet glaciers, which drain the Transantarctic Mountains and fed by the East Antarctic Ice Sheet, advancing during moist warmer periods, apparently out of phase with colder arid dry periods. Significantly the ice core record during these warm periods also shows increased accumulation continent wide The geomorphology of the Denton Hills in the Royal Society Range, West Antarctica, is a result of Miocene fluvial incision reworked by subsequent glacial advances throughout the Quaternary. The Garwood and Miers glacial valleys drain ice across the Denton Hills into the Shelf, and should thus show maximum extent during interstadials. To understand the chronology of late Quaternary glaciations, 15 granitic boulders from terminal moraines were sampled for 10Be and 26Al cosmogenic dating. Obtaining reliable exposure ages of erratics within moraines that represent timing of deposition (i.e. glacial advances) is problematic in polar regions, where glacial activity is principally controlled by ice sheet dynamics. Recycling of previously exposed debris, uncertainty in provenance of glacially transported boulders and a lack of a post-depositional hydrologic process to remove previously exposed material from a valley system, leads to ambiguities in multiple exposure ages from a single coeval glacial landform. More importantly, cold-based ice advance can leave a landform unmodified resulting in young erratics deposited on bedrock that shows weathering and/or inconsistent age-altitude relationships. Primarily, inheritance becomes a difficulty in qualifying exposure ages from polar regions. Preliminary results from the Garwood and Miers Valleys indicate that glaciers in the Denton Hills had begun to retreat from their last maximum positions no later than 23-37 ka, and thus the local last glacial maximum

  5. Synchronizing Greenland ice-core records and the Meerfelder maar sediment record via the global cosmogenic radionuclide signature and insights on climate around 11,230 years BP

    Science.gov (United States)

    Mekhaldi, F.; Czymzik, M.; Brauer, A.; Martin-Puertas, C.; Aldahan, A.; Possnert, G.; Muscheler, R.

    2017-12-01

    The causal investigation of multiple paleoclimate records relies on the accuracy of their respective chronostratigraphy. To achieve relative synchronization, cosmogenic radionuclides are an excellent tool because their common signature is global and can be retrieved and measured in different paleoclimate archives. For instance, 10Be can be measured in both ice cores and lake sediments (Berggren et al., 2013; Czymzik et al., 2016) which allows for both archives to be anchored onto radiocarbon timescales by synchronizing 10Be with 14C. We investigate the period 11,500-11,000 years BP when a short cold climate spell is known, from ice-core proxy records, to have occurred in Greenland shortly after the onset of the Holocene - the Preboreal Oscillation (PBO). This period also coincides with one of the largest and longest-lived increase in 14C production rate during the Holocene, which most likely corresponds to a grand solar minimum (around 11,230-11,000 years BP). In consequence, this period ideally illustrates the potential of using a known and clear signal in the production rate of cosmogenic radionuclides as a synchronizing tool, such as caused by large variations in solar activity. Here we measure 10Be in Meerfelder Maar (a well-dated and widely used sediment record from Germany) around 11,230 years BP which allows us to align the 10Be signal in both the Meerfelder Maar (MFM) sediment record and the GRIP ice core to IntCal13. Doing so, we report that i) the structure of the grand solar minimum is well-preserved in the 10Be signal of MFM sediments, ii) the PBO in Greenland occurs during high levels of solar activity and is not clearly observed in MFM, and iii) the PBO in Greenland ends precisely at the onset of the grand solar minimum at 11,230 years BP which also corresponds to a depositional change in MFM sediments (Martin-Puertas et al., 2017). These results thus suggest that changes in solar activity could have been a forcing at play eventually resulting in the

  6. Simultaneous measurement of angular distribution of elastic scattering for {sup 6}Li, {sup 7}Be, and {sup 8}B in {sup 58}Ni; Medida simultanea de Distribuciones Angulares de Dispersion Elastica para {sup 6}Li, {sup 7}Be, y {sup 8}B en {sup 58}Ni

    Energy Technology Data Exchange (ETDEWEB)

    Ruiz S, A. [Facultad de Ciencias, UAEM, Toluca, Estado de Mexico (Mexico); Martinez Q, E.; Aguilera R, E.F.; Murillo O, G.; Lizcano C, D.; Gomez C, A. [Departamento de Aceleradores, ININ, 52750 La Marquesa, Estado de Mexico (Mexico)

    2007-07-01

    The experimental angular distributions of elastic scattering for the projectiles {sup 6}Li, {sup 7}Be, {sup 8}B in {sup 58}Ni were obtained. Using the Optical model with a Woods-Saxon potential form, as much for the real part as for the imaginary one, an adjustment to the experimental data varying only the depth of the imaginary part of the potential is made. A comparison of the results obtained for each projectile is made. (Author)

  7. 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)

    Science.gov (United States)

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

    2010-12-01

    Because the intensity and energy spectrum of the cosmic ray flux is affected by atmospheric depth and geomagnetic-field strength, cosmogenic nuclide production rates increase considerably with altitude and to a lesser degree with latitude. The scaling methods used to account for spatial variability in production rates assume that all cosmogenic nuclides have the same altitude dependence. In this study we evaluate whether the production rates of cosmogenic 36Cl, 3He and 21Ne change differently with altitude, which is plausible due to the different energy-thresholds of their production reactions. If so, nuclide-specific scaling factors would be required. Concentrations of the three cosmogenic nuclides were determined in mafic phenocrysts over an altitude transect between 1000 and 4300 m at Kilimanjaro volcano (3° S). Altitude-dependence of relative production rates was assessed in two ways: by determination of concentration ratios and by calculation of apparent exposure age ratios for all nuclide pairs. The latter accounts for characteristics of 36Cl that the stable nuclides 3He and 21Ne do not possess (radioactive decay, high sensitivity to mineral composition and significant contributions from production reactions other than spallation). All ratios overlap within error over the entire transect, and altitudinal variation in relative production rates is not therefore evident. This suggests that nuclide-specific scaling factors are not required for the studied nuclides at this low latitude location. However, because previous studies [1,2] documented anomalous altitude-dependent variations of 3He production at mid-latitude sites, the effect of latitude on cross-calibrations should be further evaluated. We determined cosmogenic 21Ne/3He concentration ratios of 0.187 ± 0.010 in pyroxenes and 0.375 ± 0.015 in olivines, agreeing with those reported in previous studies. Despite the absence of independently determined ages for the studied lava surfaces, the consistency in

  8. Development of liquid-lithium film jet-flow for the target of (7)Li(p,n)(7)Be reactions for BNCT.

    Science.gov (United States)

    Kobayashi, Tooru; Miura, Kuniaki; Hayashizaki, Noriyosu; Aritomi, Masanori

    2014-06-01

    A feasibility study on liquid lithium target in the form of a flowing film was performed to evaluate its potential use as a neutron generation target of (7)Li(p,n)(7)Be reaction in BNCT. The target is a windowless-type flowing film on a concave wall. Its configuration was adapted for a proton beam which is 30mm in diameter and with energy and current of up to 3MeV and 20mA, respectively. The flowing film of liquid lithium was 0.6mm in thickness, 50mm in width and 50mm in length. The shapes of the nozzle and concave back wall, which create a stable flowing film jet, were decided based on water experiments. A lithium hydrodynamic experiment was performed to observe the stability of liquid lithium flow behavior. The flowing film of liquid lithium was found to be feasible at temperatures below the liquid lithium boiling saturation of 342°C at the surface pressure of 1×10(-3)Pa. Using a proto-type liquid lithium-circulating loop for BNCT, the stability of the film flow was confirmed for velocities up to 30m/s at 220°C and 250°C in vacuum at a pressure lower than 10(-3) Pa. It is expected that for practical use, a flowing liquid lithium target of a windowless type can solve the problem of radiation damage and target cooling. Copyright © 2013 Elsevier Ltd. All rights reserved.

  9. Uplift rates of the marine terraces in the south coast of Japan deduced from in situ cosmogenic 10Be and 26Al

    Science.gov (United States)

    Yokoyama, Y.; Nagano, G.; Nakamura, A.; Maemoku, H.; Miyairi, Y.; Matsuzaki, H.

    2015-12-01

    Marine terraces are low-relief platforms located along coastal areas. They are formed by waves action with the changes in the relative sea level (RSL) that is affected by combined effects of the eustatic sea level (ESL) and the tectonic movements (e.g. uplift, subsidence and isostatic effect). Therefore, determining the ages and the elevations of the marine terraces allows us to reconstruct the ESL and/or the tectonic history of the study area. The Kii Peninsula and the southern coast of the Shikoku Island are located along the Nankai Trough where the Philippine Sea Plate is subducting under the Eurasian plate. There exist relatively well-preserved marine terraces along the coastal line with the elevation of ca. 50 -100 m. Because of this unique tectonic setting, the terraces are regarded as the suitable counterparts to reconstruct uplift history of the south coast of Japan. However, the ages of these terraces are poorly understood due to the lack of the ash layers that is suitable for the tephrochronology. In this study, we determine the age of the marine terraces using terrestrial in-situ cosmogenic radionuclides (TCN), 10Be and 26Al. This is the first age estimation of the marine terraces in Japan using TCN, allowing us to determine the uplift rates and the seismic history of the region.

  10. Balance of the tropospheric ozone and its relation to stratospheric intrusions indicated by cosmogenic radionuclides. Part 13. Annual report, 1 February 1982-31 January 1983

    International Nuclear Information System (INIS)

    Reiter, R.; Kanter, H.J.; Jaeger, H.; Munzert, K.

    1985-06-01

    A statistical evaluation of tropospheric ozone concentrations in the air obtained at 3 different levels is presented from data covering 1977 to 1984. Annual and interannual variations are used to project a trend. To clarify the climatology of the stratospheric exchange, the measuring series of cosmogenic radionuclides Be7, P32, P33 covering the period 1970 through 1981 are statistically analyzed with regard to the ozone concentration recorded on the Zugspitze. The statistics of stratospheric intrusions is shown and the stratospheric residence time is estimated. Effects of the eruption of volcano El Chichon in April 1982 on the concentration of the stratospheric aerosol are documented. The time variation of the concentration of the stratospheric aerosol is studied with consideration of the stratospheric circulation. The noted effects are weighed by a comparison with earlier volcanic eruptions. First results of CO 2 recordings in the lower stratosphere are presented. Based on CO 2 recording series from two different levels (740 m and 1780 m a.s.1) from the years 1978 to 1980, systematic differences are shown as a function of height. The question of sources and sinks is discussed to assess the contribution from anthropogenic sources

  11. Balance of the tropospheric ozone and its relation to stratospheric intrusions indicated by cosmogenic radionuclides. Technical progress report, 1 November 1978-30 June 1979

    International Nuclear Information System (INIS)

    Reiter, R.; Kanter, H.J.; Poetzl, K.; Sladkovic, R.; Jaeger, H.; Mueller, H.

    The balance of the tropospheric ozone as a function of atmospheric pollutants, tropospheric transport, and stratospheric intrusions is under active investigation. Continuous recordings of the ozone concentration at three levels (3000 m, 1800 m, and 700 m a.s.l.) and of the cosmogenic radionuclides Be 7 , P 32 , P 33 , and the CO 2 are available and used for subject purposes. Results of a statistical evaluation concerning the frequency of high concentrations (> 70 ppB) of the tropospheric ozone are presented and possible sources discussed. Observations of changes in the fine structure of the ozone profile in the lower stratosphere after solar events are shown by balloon-borne ozone soundings up to 35 km altitude and discussed in connection with parameters of the stratospheric-tropospheric exchange. Monitoring of the stratospheric aerosol layer by lidar was continued. The accuracy of these measurements was considerably enhanced by significant system improvements. Intercomparisons with the results of nearby Dobson stations allowed conclusions to be drawn on the suitability of a filter spectrophotometer for the determination of the total ozone. Solar-terrestrial relationships were investigated and are discussed

  12. The determination of irradiation and so-called terrestrial ageing of rock meteorites based on the cosmogenic resulting radionuclides 53Mn and 26Al

    International Nuclear Information System (INIS)

    Englert, P.

    1979-01-01

    The contents of cosmogenic occuring 53 Mn was determined by neutron activation in over 90 samples of 75 individual rock meteorites. The distinct depth effect of the 53 Mn production rate in rock meteorites could be measured by a depth profile at LL6 chondrite St. Severin (falling weight 271 kg). The experimental results confirm the present model concepts. By comparing with the spallogenic 22 Ne/ 21 Ne and 3 He/ 21 Ne ratios applicable as depth indicators, one could derive linear relationships suitable for correcting 53 Mn. They enable the determination of the average 53 Mn production rate from the saturation activities of long-term irradiated meteorites. Using this method it was possible to calculate the irradiation age of 40 rock meteorites. As 26 Al is formed with a similar effective cross-section to 53 Mn, the production rate ratio 53 Mn: 26 Al was also taken to derive the depth-independent irradiation ages. A method to determine the depth-independent terrestrial ageing of meteriorites has been developed based on the same isotope ratio, the effective field of application is between 0.10 to 2x10 6 a. Furthermore, an attempt was made to draw up the dependence of noble gas contents of 53 Mn resp. 53 Mn/ 26 Al irradiation age for the new determination of the 3 He, 21 Ne and 38 Ar production rates by means of a linear regression analysis. (orig./RB) [de

  13. Quantifying the sources and the transit times of sediment using fallout radionuclides (7Be, 137Cs, 210Pbxs) in contrasted cultivated catchments across the world

    Science.gov (United States)

    Evrard, O.; Le Gall, M.; Laceby, J. P.; Foucher, A.; Lefèvre, I.; Salvador-Blanes, S.; Morera, S.; Ribolzi, O.

    2017-12-01

    Soil erosion and fine sediment supply to rivers are exacerbated in intensively cultivated catchments. Information on the sediment sources and transit times in rivers is required to improve our understanding of these processes and to guide the implementation of effective conservation measures. Accordingly, natural (7Be, 210Pb) and artificial (137Cs) fallout radionuclide concentrations were measured in overland flow and suspended sediment collected during the erosive season in contrasted cultivated catchments. In Laos, samples were collected in a steep catchment (Houay Pano, 12 km²) covered with cropland and teak plantations during the first flood of the monsoon in 2014. Cropland surface sources dominated the supply of sediment at the upstream sampling location (55%), whereas subsurface sources (channel, landslides) contributed the majority of material at the outlet (60%). Furthermore, the material exported from the catchment mainly consisted of re-suspended sediment. In Central France, the study was conducted in a flat and drained cultivated catchment (Louroux, 25 km²) during a sequence of winter events in 2013-2014 and 2016. Only surface material enriched in 137Cs was found to transit through the river during floods. The results demonstrated the initial re-suspension of material accumulated in the river channel during the first winter flood before the direct supply of sediment recently eroded from the hillslopes during the next events. In Peru, sediment was collected during a series of summer flood events (2017) in a river draining páramos (Ronquillo, 42 km²) that were recently put in cultivation. Preliminary results show that subsurface re-suspended material dominates the exports from this catchment. These results confirmed the utility of coupling continuous river monitoring and fallout radionuclide measurements on sediment collected in both tropical and temperate rivers to better understand sediment dynamics in these endangered habitats. The main challenges

  14. Evaluation of the characteristics of boron-dose enhancer (BDE) materials for BNCT using near threshold {sup 7}Li(p,n){sup 7}Be direct neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Bengua, Gerard [Research Reactor Institute, Kyoto University, Kumatori-cho, Sennann-gun, Osaka 590-0494 (Japan); Kobayashi, Tooru [Research Reactor Institute, Kyoto University, Kumatori-cho, Sennann-gun, Osaka 590-0494 (Japan); Tanaka, Kenichi [Research Institute for Radiation Biology and Medicine, Hiroshima University, Kasumi, Minami-ku, Hiroshima 734-8553 (Japan); Nakagawa, Yoshinobu [National Kagawa Children' s Hospital, Zentsuji-cho, Zentsuji, Kagawa 765-8501 (Japan)

    2004-03-07

    The characteristics of a number of candidate boron-dose enhancer (BDE) materials for boron neutron capture therapy (BNCT) using near threshold {sup 7}Li(p,n){sup 7}Be direct neutrons were evaluated based on the treatable protocol depth (TPD), defined in this paper. Simulation calculations were carried out by means of MCNP-4B transport code for candidate BDE materials, namely, (C{sub 2}H{sub 4}){sub n}, (C{sub 2}H{sub 3}F){sub n}, (C{sub 2}H{sub 2}F{sub 2}){sub n}, (C{sub 2}HF{sub 3}){sub n}, (C{sub 2}D{sub 4}){sub n}, (C{sub 2}F{sub 4}){sub n}, beryllium metal, graphite, D{sub 2}O and {sup 7}LiF. Dose protocols applied were those used for intra-operative BNCT treatment for brain tumour currently used in Japan. The maximum TPD (TPD{sub max}) for each BDE material was found to be between 4 cm and 5 cm in the order of (C{sub 2}H{sub 4}){sub n} < (C{sub 2}H{sub 3}F){sub n} < (C{sub 2}H{sub 2}F{sub 2}){sub n} < (C{sub 2}HF{sub 3}){sub n} < beryllium metal < (C{sub 2}D{sub 4}){sub n} < graphite < (C{sub 2}F{sub 4}){sub n} < D{sub 2}O < {sup 7}LiF. Based on the small and arbitrary variations in the TPD{sub max} for these materials, an explicit advantage of a candidate BDE material could not be established from the TPD{sub max} alone. The dependence of TPD on BDE thickness was found to be influenced by the type of BDE material. For materials with hydrogen, sharp variations in TPD were observed, while those without hydrogen exhibited more moderate fluctuations in TPD as the BDE thickness was varied. The BDE thickness corresponding to TPD{sub max} (BDE(TPD{sub max})) was also found to depend on the type of BDE material used. Thicker BDE(TPD{sub max}), obtained mostly for BDE materials without hydrogen, significantly reduced the dose rates within the phantom. The TPD{sub max}, the dependence of TPD on BDE thickness and the BDE (TPD{sub max}) were ascertained as appropriate optimization criteria in choosing suitable BDE materials for BNCT. Among the candidate BDE materials

  15. Contribution to the study of excited levels of {sup 7}Be obtained from the reaction {sup 6}Li (p, {alpha}); Contribution a l'etude des niveaux excites du {sup 7}Be obtenus par la reaction {sup 6}Li (p, {alpha})

    Energy Technology Data Exchange (ETDEWEB)

    Beaumevieille, H. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1964-05-01

    The interpretation of the results of the reaction {sup 6}Li (p, {alpha}) in the energy range 100 keV to 3 MeV has been done with the next levels of {sup 7}Be : 3/2- (5,9 MeV), 3/2+ (6,2 MeV), 5/2- (7,18 MeV) and a level the characteristics of which may be 1/2+ or {sup 4}P (9,5 MeV). (author) [French] L'interpretation des resultats de la reaction {sup 6}Li (p, {alpha}) dans la gamme d'energie 100 keV a 3 MeV a ete faite avec les niveaux suivants du {sup 7}Be : 3/2- (5,9 MeV), 3/2 + (6,2 MeV), 5/2- (7,18 MeV) et un niveau dont les caracteristiques doivent etre 1/2+ ou {sup 4}P (9,5 MeV). (auteur)

  16. Contribution to the study of excited levels of {sup 7}Be obtained from the reaction {sup 6}Li (p, {alpha}); Contribution a l'etude des niveaux excites du {sup 7}Be obtenus par la reaction {sup 6}Li (p, {alpha})

    Energy Technology Data Exchange (ETDEWEB)

    Beaumevieille, H [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1964-05-01

    The interpretation of the results of the reaction {sup 6}Li (p, {alpha}) in the energy range 100 keV to 3 MeV has been done with the next levels of {sup 7}Be : 3/2- (5,9 MeV), 3/2+ (6,2 MeV), 5/2- (7,18 MeV) and a level the characteristics of which may be 1/2+ or {sup 4}P (9,5 MeV). (author) [French] L'interpretation des resultats de la reaction {sup 6}Li (p, {alpha}) dans la gamme d'energie 100 keV a 3 MeV a ete faite avec les niveaux suivants du {sup 7}Be : 3/2- (5,9 MeV), 3/2 + (6,2 MeV), 5/2- (7,18 MeV) et un niveau dont les caracteristiques doivent etre 1/2+ ou {sup 4}P (9,5 MeV). (auteur)

  17. Unraveling the Quaternary river incision in the Moselle valley (Rhenish Massif, Germany): new insights from cosmogenic nuclide dating (10Be/26Al) of the Main Terrace complex

    Science.gov (United States)

    Rixhon, Gilles; Cordier, Stéphane; Harmand, Dominique; May, Simon Matthias; Kelterbaum, Daniel; Dunai, Tibor; Binnie, Steven; Brückner, Helmut

    2014-05-01

    Throughout the whole river network of the Rhenish Massif, the terrace complex of the so-called Main Terrace forms the morphological transition between a wide upper palaeovalley (plateau valley) and a deeply incised lower valley. The youngest level of this Main Terrace complex (YMT), directly located at the edge of the incised valley, represents a dominant geomorphic feature in the terrace flight; it is often used as a reference level to identify the start of the main middle Pleistocene incision episode (Demoulin & Hallot, 2009). The latter probably reflects the major tectonic pulse that affected the whole Massif and was related to an acceleration of the uplift rates (Demoulin & Hallot, 2009). The Main terraces are particularly well preserved in the lower Moselle valley and are characterized by a constant absolute elevation of their base along a 150 km-long reach. Despite that various hypotheses have been proposed to explain this horizontality (updoming, faulting...), all studies assumed an age of ca. 800 ka for the YMT, mainly based on the questionable extrapolation of palaeomagnetic data obtained in the Rhine valley. Therefore, a reliable chronological framework is still required to unravel the spatio-temporal characteristics of the Pleistocene evolution of the Moselle valley. In this study, we apply cosmogenic nuclide dating (10Be/26Al) to fluvial sediments pertaining to the Main Terrace complex or to the upper Middle Terraces. Several sites along the lower Moselle were sampled following two distinct sampling strategies: (i) depth profiles where the original terrace (palaeo-)surface is well preserved and did not experience much postdepositional burial (e.g., loess cover); and (ii) the isochron technique where the sediment thickness exceeds 3 m. Cosmogenic nuclide ages recently obtained for three rivers in the Meuse catchment in the western Rhenish Massif demonstrated that the Main Terraces were younger than expected and their abandonment was diachronic along the

  18. Authigenic 10Be/9Be ratio signatures of the cosmogenic nuclide production linked to geomagnetic dipole moment variation since the Brunhes/Matuyama boundary.

    Science.gov (United States)

    Simon, Quentin; Thouveny, Nicolas; Bourlès, Didier L; Valet, Jean-Pierre; Bassinot, Franck; Ménabréaz, Lucie; Guillou, Valéry; Choy, Sandrine; Beaufort, Luc

    2016-11-01

    Geomagnetic dipole moment variations associated with polarity reversals and excursions are expressed by large changes of the cosmogenic nuclide beryllium-10 ( 10 Be) production rates. Authigenic 10 Be/ 9 Be ratios (proxy of atmospheric 10 Be production) from oceanic cores therefore complete the classical information derived from relative paleointensity (RPI) records. This study presents new authigenic 10 Be/ 9 Be ratio results obtained from cores MD05-2920 and MD05-2930 collected in the west equatorial Pacific Ocean. Be ratios from cores MD05-2920, MD05-2930 and MD90-0961 have been stacked and averaged. Variations of the authigenic 10 Be/ 9 Be ratio are analyzed and compared with the geomagnetic dipole low series reported from global RPI stacks. The largest 10 Be overproduction episodes are related to dipole field collapses (below a threshold of 2 × 10 22  Am 2 ) associated with the Brunhes/Matuyama reversal, the Laschamp (41 ka) excursion, and the Iceland Basin event (190 ka). Other significant 10 Be production peaks are correlated to geomagnetic excursions reported in literature. The record was then calibrated by using absolute dipole moment values drawn from the Geomagia and Pint paleointensity value databases. The 10 Be-derived geomagnetic dipole moment record, independent from sedimentary paleomagnetic data, covers the Brunhes-Matuyama transition and the whole Brunhes Chron. It provides new and complementary data on the amplitude and timing of millennial-scale geomagnetic dipole moment variations and particularly on dipole moment collapses triggering polarity instabilities.

  19. A minimum age for Llullaillaco south flow from cosmogenic 3He: Much older than 19th century

    International Nuclear Information System (INIS)

    Niedermann, S.; Althau, T.; Hahne, K

    2001-01-01

    Dating of Holocene lava flows can be a difficult task in cases when buried organic material suitable for 14 C dating is lacking, as typical for arid climatic conditions. Cosmic-ray-produced nuclides may provide an alternative dating method, especially for lava flows exposed at high altitudes: When cosmic ray particles (predominantly secondary neutrons) interact with terrestrial surface rocks, they can produce a variety of stable and radioactive nuclides by spallation reactions with target elements in the crystal lattice (e.g. Lal, 1988; Cerling and Craig, 1994). Some of these nuclides, such as the noble gas isotopes 3 He and 21 Ne or the radionuclides 10 Be, 26 Al, and 36 Cl, can be detected mass-spectrometrically, and their concentration can be used to determine the duration of the rock exposure on the surface as production rates decrease rapidly with depth. The intensity of cosmic rays increases with altitude due to the reduced shielding by the atmosphere, therefore production rates at 4000 m are more than an order of magnitude higher than at sea level (Lal, 1991; Dunai, 2000). The Central Volcanic Zone (CVZ) in the Andes of northern Chile is a region of prevailing arid climate, where a lot of prehistoric lava flows are still undated. Typically, high elevations and low erosion rates render them well suited for surface exposure dating. However, there are a few obstacles also. Many lavas in the CVZ have andesitic to dacitic compositions and a very small-grained structure. The most abundant rock-forming mineral plagioclase is known not to retain the light noble gases He and Ne quantitatively, but separation of more retentive minerals cannot easily be achieved. Also, the isotopic composition of magmatic He in these lavas is not very well constrained. Hilton et al. (1993) report 3 He/ 4 He ratios between 0.8 and 6.0 R A (R A = 1.39x10 -6 is the 3 He/ 4 He ratio in the atmosphere) for olivine and clinopyroxene phenocrysts from CVZ lavas. Such a range of compositions

  20. The particulate 7Be/210Pbxs and 234Th/210Pbxs activity ratios as tracers for tidal-to-seasonal particle dynamics in the Gironde estuary (France): Implications for the budget of particle-associated contaminants

    International Nuclear Information System (INIS)

    Saari, Hanna-Kaisa; Schmidt, Sabine; Castaing, Patrice; Blanc, Gerard; Sautour, Benoit; Masson, Olivier; Cochran, J. Kirk

    2010-01-01

    The short-lived natural radionuclides 7 Be (T 1/2 = 53 days), 234 Th xs (T 1/2 = 24.1 days) and 210 Pb xs (T 1/2 = 22.3 years), i.e. 234 Th and 210 Pb in excesses of that supported within particles by the decay of their parent isotopes, were analysed in suspended particulate matter (SPM) to study the particle dynamics in the Gironde fluvial estuarine system (France), strongly impacted by heavy metal pollution. From surveys of this land-ocean interface in 2006 and 2007, we established a times series of these radioisotopes and of their activity ratios ( 7 Be/ 210 Pb xs and 234 Th/ 210 Pb xs ARs) in particles sampled under different hydrological conditions. The particulate 7 Be/ 210 Pb xs AR varies along the fluvial estuarine system mainly due to variations in 7 Be activities, controlled by riverine, oceanic and atmospheric inputs and by resuspension of old 7 Be-deficient sediments. These processes vary with river discharge, tidal cycle and season. Therefore, seasonal particle transport processes can be described using variations of the SPM 7 Be/ 210 Pb xs ARs. During high river discharge, the SPM 7 Be/ 210 Pb x ARs decrease from river to the ocean. The turbidity maximum zone (TMZ) is dispersed and the particles, and the associated contaminants, are rapidly transported from river to coastal waters, without significant retention within the TMZ. During low river discharge, the TMZ intrudes into the fluvial estuary, and the lowest 7 Be/ 210 Pb x ARs are observed there due to resuspension of 7 Be-deficient sediments. Away from the TMZ, from the middle to lower estuary, SPM 7 Be/ 210 Pb x ARs increase, indicating that the particles have been recently tagged with 7 Be. We explain this trend as being caused by marine input of dissolved radionuclides, as traced by SPM 234 Th/ 210 Pb xs ARs, followed by scavenging in the estuary. This result indicates that particle transport models based on 7 Be and trace-metal budgets must consider oceanic dissolved inputs as an additional

  1. Measurements of neutron emission spectra and {sup 7}Be production in Li(d, n) and Be(d, n) reactions for 25 and 40 MeV deuterons

    Energy Technology Data Exchange (ETDEWEB)

    Hagiwara, Masayuki; Baba, Mamoru; Aoki, Takao; Kawata, Naoki; Hirabayashi, Naoya; Itoga, Toshiro [Tohoku Univ., Cyclotron and Radioisotope Center, Sendai, Miyagi (Japan)

    2003-06-01

    The neutron spectra in Li(d, n) and Be(d, n) reactions for Ed = 25, 40 MeV were measured from {approx}1 MeV to highest energy of secondary neutrons at ten laboratory angles between 0- and 110-deg with the time-of-flight (TOF) method. In addition, the number of {sup 7}Be accumulated in the targets was also measured by counting the {gamma}-rays from {sup 7}Be using a pure Ge detector to obtain {sup 7}Be production cross-section and yields. (author)

  2. Coupling erosion and topographic development in the rainiest place on Earth: Reconstructing the Shillong Plateau uplift history with in-situ cosmogenic 10Be

    Science.gov (United States)

    Rosenkranz, Ruben; Schildgen, Taylor; Wittmann, Hella; Spiegel, Cornelia

    2018-02-01

    The uplift of the Shillong Plateau, in northeast India between the Bengal floodplain and the Himalaya Mountains, has had a significant impact on regional precipitation patterns, strain partitioning, and the path of the Brahmaputra River. Today, the plateau receives the highest measured yearly rainfall in the world and is tectonically active, having hosted one of the strongest intra-plate earthquakes ever recorded. Despite the unique tectonic and climatic setting of this prominent landscape feature, its exhumation and surface uplift history are poorly constrained. We collected 14 detrital river sand and 3 bedrock samples from the southern margin of the Shillong Plateau to measure erosion rates using the terrestrial cosmogenic nuclide 10Be. The calculated bedrock erosion rates range from 2.0 to 5.6 m My-1, whereas catchment average erosion rates from detrital river sands range from 48 to 214 m My-1. These rates are surprisingly low in the context of steep, tectonically active slopes and extreme rainfall. Moreover, the highest among these rates, which occur on the low-relief plateau surface, appear to have been affected by anthropogenic land-use change. To determine the onset of surface uplift, we coupled the catchment averaged erosion rates with topographic analyses of the plateau's southern margin. We interpolated an inclined, pre-incision surface from minimally eroded remnants along the valley interfluves and calculated the eroded volume of the valleys carved beneath the surface. The missing volume was then divided by the volume flux derived from the erosion rates to obtain the onset of uplift. The results of this calculation, ranging from 3.0 to 5.0 Ma for individual valleys, are in agreement with several lines of stratigraphic evidence from the Brahmaputra and Bengal basin that constrain the onset of topographic uplift, specifically the onset of flexural loading and the transgression from deltaic to marine deposition. Ultimately, our data corroborate the

  3. Cosmogenic signature of geomagnetic reversals and excursions from the Réunion event to the Matuyama-Brunhes transition (0.7-2.14 Ma interval)

    Science.gov (United States)

    Simon, Quentin; Bourlès, Didier L.; Thouveny, Nicolas; Horng, Chorng-Shern; Valet, Jean-Pierre; Bassinot, Franck; Choy, Sandrine

    2018-01-01

    Long-term variations of the geomagnetic dipole moment (GDM) during periods of stable polarity and in transitional states (reversals and excursions) provide key information for understanding the geodynamo regime. Following several studies dealing with the Brunhes chron and the Matuyama-Brunhes transition, this study presents a new authigenic 10Be/9Be ratio (Be-ratio) record obtained from the MD97-2143 core (western Pacific Ocean). This new Be-ratio series yields a record of GDM variations covering the early Brunhes and mid to late Matuyama time period (i.e. 700-2140 ka), independently from the relative paleointensity (RPI) record obtained from the same core, that can be compared with available RPI records and stacks. Stratigraphic offsets measured between the Be-ratio peaks and the corresponding RPI minima reach 2 to 14 cm. They can be assigned to (post-) detrital remanent magnetization (pDRM) effects leading to magnetization locking-in delays varying from 2 to 12 ka in the studied core. 10Be overproduction episodes triggered by geomagnetic dipole moment lows (GDL) linked to polarity reversals and excursions confirm the global control exerted by the GDM on cosmogenic radionuclides production. A dipole moment reconstruction derived from the Beryllium-10 (BeDiMo) was compiled and calibrated using absolute paleointensity data. This independent record complements the available paleomagnetic RPI records, permitting 1) to overcome the pDRM lock-in offsets induced below the mixing layer, 2) to confront and increase the robustness and precision of GDM reconstructions and, 3) to better constrain the chronology of geomagnetic field instabilities during the mid to late Matuyama chron. Our new 10Be derived inventory is fully compatible with the GDL series linked to geomagnetic polarity reversals and events (Matuyama-Brunhes transition, Jaramillo and Olduvai subchron boundaries, Cobb Mountain, Réunion) and it strengthens the occurrence of several excursions (Kamikatsura, Santa

  4. Cosmogenic 10Be Dating of Northern Quebec-Labrador Glacial Lake Shorelines and Drainage Deposits: Implications for the Final Meltwater Discharges of the Last Deglaciation

    Science.gov (United States)

    Roy, M.; Dube-Loubert, H.; Schaefer, J. M.; Hébert, S.

    2017-12-01

    The decay of the Laurentide ice sheet played an important role in the climate variability of the last deglaciation, notably through large discharges of meltwater from glacial lakes that disturbed the Atlantic meridional overturning oceanic circulation (AMOC). These former climate-forcing events are now under focus due to growing evidence showing that the present-day increase in freshwater releases from Greenland and other Arctic glaciers may potentially lead to a slowdown of the AMOC and cause important climate feedbacks. In northern Quebec and Labrador, the end of the deglaciation led to the formation of at least 10 important glacial lakes that drained into the nearby Labrador Sea where repeated meltwater discharges could have destabilized the ocean surface conditions in this key sector of the North Atlantic Ocean. Although the drainage of these ice-dammed lakes may form a good analogue for modern processes, the lack of direct constraints on the physiographic configuration and temporal evolution of these lakes limits our understanding of the timing and climate impact of these final meltwater pulses. Here we applied cosmogenic 10Be dating to raised boulder shorelines belonging to Lake Naskaupi, one of the largest glacial lakes in northern Quebec and Labrador. We reconstructed the lake extent and meltwater volume, as well as its lake-level history by systematic mapping of geomorphic features. We sampled a total of 16 boulders at 4 sites along the valley. In addition, we dated five boulders belonging to a large-scale outburst flood deposit recording the abrupt drainage of the lake. The distribution of the 21 ages shows a remarkable consistency, yielding a mean age of 7.8 ± 0.4 ka (1 outlier excluded). The ages from the shorelines are indistinguishable from those of the outburst flood deposit, suggesting that Lake Naskaupi existed for a relatively short time span. These new chronological data constrain the timing of the lake development and attendant drainage

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

    Science.gov (United States)

    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

  6. Brookhaven Linac Isotope Producer

    Data.gov (United States)

    Federal Laboratory Consortium — The Brookhaven Linac Isoptope Producer (BLIP)—positioned at the forefront of research into radioisotopes used in cancer treatment and diagnosis—produces commercially...

  7. Variation of monthly inventories of {sup 7}Be fallout in the soils of the sub-basins 3 and 4 in Mato Frio river, a tributary of Serra Azul river

    Energy Technology Data Exchange (ETDEWEB)

    Esquivel, Alexander D., E-mail: alexander.esquivel@utp.ac.pa [Centro de Investigaciones Hidráulicas e Hidrotécnicas (CIHH / UTP – PA), Universidad Tecnológica de Panamá (Panama); Moreira, Rubens M., E-mail: rubens@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

    2015-07-01

    In this study 72 soil samples collected right at the surface were analyzed. They were collected at two work parcels located within the basin of the Mato Frio Creek (total drainage area = 10.6 km²) located in the municipality of Itauna, except for a small fraction in its northern part, which is located in the municipality of Serra Azul. Both municipalities are in the State of Minas Gerais, Brazil. The sampling period covers the time span from May 2014 to May 2015, with the purpose of observing on a monthly basis the variation in the activity of the radionuclide Beryllium-7 ({sup 7}Be, Eγ = 477.6 keV) along a one year hydrologic cycle, stressing the dry and rainy seasons. The objective of this investigation was to establish a baseline for the alteration pattern of the {sup 7}Be content in the soil in order to use these results for future estimates of rates of erosion or accreation in areas of interest within this basin. In order to measure the {sup 7}Be activity in the collected samples, a gamma spectrometer was used, composed of a hyperpure germanium detector with a relative efficiency of 50%. The results indicate a net trend towards a marked variation in the activity of {sup 7}Be in relative to the period of year within which the samples were collected, which in turn results in a reduction or increase in the values of the {sup 7}Be monthly inventory in the topsoil. (author)

  8. Producing charcoal from wastes

    Energy Technology Data Exchange (ETDEWEB)

    Pogorelov, V.A.

    1983-01-01

    Experimental works to use wood wastes for producing charcoal are examined, which are being conducted in the Sverdlovsk assembly and adjustment administration of Soyuzorglestekhmontazh. A wasteless prototype installation for producing fine charcoal is described, along with its subsequent briqueting, which is made on the basis of units which are series produced by the factories of the country. The installation includes subassemblies for preparing and drying the raw material and for producing the charcoal briquets. In the opinion of specialists, the charcoal produced from the wastes may be effectively used in ferrous and nonferrous metallurgy and in the production of pipes.

  9. The 10B(p,α)7Be S(E)-factor from 5 keV to 1.5 MeV using the Trojan Horse Method

    Science.gov (United States)

    Puglia, Sebastiana Maria Regina; Spitaleri, Claudio; La Cognata, Marco; Lamia, Livio; Broggini, Carlo; Caciolli, Antonio; Carlin, Nelson; Cherubini, Silvio; Cvetinovic, Alexandra; D'Agata, Giuseppe; Dell'aquila, Daniele; Depalo, Rosanna; Gulino, Marisa; Guardo, Giovanni Luca; Indelicato, Iolanda; Lombardo, Ivano; Menegazzo, Roberto; Munhoz, Marcelo Gimenez; Pizzone, Rosario Gianluca; Rapisarda, Giuseppe Gabriele; Rigato, Valentino; Romano, Stefano; Sergi, Maria Letizia; Souza, Francisco; Sparta, Roberta; Tudisco, Salvo; Tumino, Aurora

    2018-01-01

    The 10B(p,α)7Be reaction is the main responsible for the 10B destruction in stellar interior [1]. In such environments this p-capture process occurs at a Gamow energy of 10 keV and takes places mainly through a resonant state (Ex = 8.701 MeV) of the compound 11C nucleus. Thus a resonance right in the region of the Gamow peak is expected to significantly influence the behavior of the astrophysical S(E)-factor. The 10B(p,α)7Be reaction was studied via the Trojan Horse Method (THM) applied to the 2H(10B,α7Be)n in order to extract the astrophysical S(E)-factor in a wide energy range from 5 keV to 1.5 MeV.

  10. Balance of the tropospheric ozone and its relation to stratospheric intrusions indicated by cosmogenic radionuclides. Part 14. Final technical report, 1 November 1977-31 January 1984

    International Nuclear Information System (INIS)

    Reiter, R.; Kanter, H.J.; Jaeger, H.; Munzert, K.

    1985-01-01

    The objective was to clarify the effect of stratospheric intrusions on the tropospheric ozone budget. The correlation between stratospheric-tropospheric exchange and solar events was also investigated. Tropospheric ozone was recorded at three different levels. The radioisotopes 7 Be and radon daughter products 214 Pb and 214 Bi were used as tracers to identify the source of ozone

  11. A listing of cosmogenic, optically-stimulated-luminescence, (U-Th)/He, and fission-track sample locations, analyses, and age data compiled as part of Marsden contract GNS002 (2000-2004) : subduction initiation beneath Fiordland, southwest New Zealand

    International Nuclear Information System (INIS)

    Sutherland, R.

    2007-01-01

    This report is an archive of data relevant to Fiordland tectonic evolution. Specifically these are the data that were collected and compiled as part of Marsden contract GNS002 (2000-2004); samples were collected between 1987 and 2002. The principal investigator of the Marsden Fund project was Rupert Sutherland (GNS Science). Additional named investigators (with responsibilities and affiliations) were: Kyeong Kim (cosmogenic isotope dating; GNS Science); Peter Kamp (fission track dating; Waikato University); Martha House (U-Th/He dating; Caltech, USA); and Michael Gurnis (numerical models of subduction initiation; Caltech, USA). After the project began, Uwe Rieser from Victoria University agreed to undertake optically-stimulated luminescence (OSL) dating as part of the project. (author). 6 refs

  12. ^{7}Be(n,α)^{4}He Reaction and the Cosmological Lithium Problem: Measurement of the Cross Section in a Wide Energy Range at n_TOF at CERN.

    Science.gov (United States)

    Barbagallo, M; Musumarra, A; Cosentino, L; Maugeri, E; Heinitz, S; Mengoni, A; Dressler, R; Schumann, D; Käppeler, F; Colonna, N; Finocchiaro, P; Ayranov, M; Damone, L; Kivel, N; Aberle, O; Altstadt, S; Andrzejewski, J; Audouin, L; Bacak, M; Balibrea-Correa, J; Barros, S; Bécares, V; Bečvář, F; Beinrucker, C; Berthoumieux, E; Billowes, J; Bosnar, D; Brugger, M; Caamaño, M; Calviani, M; Calviño, F; Cano-Ott, D; Cardella, R; Casanovas, A; Castelluccio, D M; Cerutti, F; Chen, Y H; Chiaveri, E; Cortés, G; Cortés-Giraldo, M A; Cristallo, S; Diakaki, M; Domingo-Pardo, C; Dupont, E; Duran, I; Fernandez-Dominguez, B; Ferrari, A; Ferreira, P; Furman, W; Ganesan, S; García-Rios, A; Gawlik, A; Glodariu, T; Göbel, K; Gonçalves, I F; González-Romero, E; Griesmayer, E; Guerrero, C; Gunsing, F; Harada, H; Heftrich, T; Heyse, J; Jenkins, D G; Jericha, E; Katabuchi, T; Kavrigin, P; Kimura, A; Kokkoris, M; Krtička, M; Leal-Cidoncha, E; Lerendegui, J; Lederer, C; Leeb, H; Lo Meo, S; Lonsdale, S J; Losito, R; Macina, D; Marganiec, J; Martínez, T; Massimi, C; Mastinu, P; Mastromarco, M; Mazzone, A; Mendoza, E; Milazzo, P M; Mingrone, F; Mirea, M; Montesano, S; Nolte, R; Oprea, A; Pappalardo, A; Patronis, N; Pavlik, A; Perkowski, J; Piscopo, M; Plompen, A; Porras, I; Praena, J; Quesada, J; Rajeev, K; Rauscher, T; Reifarth, R; Riego-Perez, A; Rout, P; Rubbia, C; Ryan, J; Sabate-Gilarte, M; Saxena, A; Schillebeeckx, P; Schmidt, S; Sedyshev, P; Smith, A G; Stamatopoulos, A; Tagliente, G; Tain, J L; Tarifeño-Saldivia, A; Tassan-Got, L; Tsinganis, A; Valenta, S; Vannini, G; Variale, V; Vaz, P; Ventura, A; Vlachoudis, V; Vlastou, R; Vollaire, J; Wallner, A; Warren, S; Weigand, M; Weiß, C; Wolf, C; Woods, P J; Wright, T; Žugec, P

    2016-10-07

    The energy-dependent cross section of the ^{7}Be(n,α)^{4}He reaction, of interest for the so-called cosmological lithium problem in big bang nucleosynthesis, has been measured for the first time from 10 meV to 10 keV neutron energy. The challenges posed by the short half-life of ^{7}Be and by the low reaction cross section have been overcome at n_TOF thanks to an unprecedented combination of the extremely high luminosity and good resolution of the neutron beam in the new experimental area (EAR2) of the n_TOF facility at CERN, the availability of a sufficient amount of chemically pure ^{7}Be, and a specifically designed experimental setup. Coincidences between the two alpha particles have been recorded in two Si-^{7}Be-Si arrays placed directly in the neutron beam. The present results are consistent, at thermal neutron energy, with the only previous measurement performed in the 1960s at a nuclear reactor. The energy dependence reported here clearly indicates the inadequacy of the cross section estimates currently used in BBN calculations. Although new measurements at higher neutron energy may still be needed, the n_TOF results hint at a minor role of this reaction in BBN, leaving the long-standing cosmological lithium problem unsolved.

  13. Aerosol Characterization at the WMO-GAW Station of Mt. Cimone (2165 m a.s.I.) BY {sup 7}Be, {sup 210}Pb and PM{sub 10}

    Energy Technology Data Exchange (ETDEWEB)

    Tositti, L. [Dipartimento di Chimica ' Giacomo Ciamician' , Laboratorio di Chimica Ambientale e Radioattivita, Universita di Bologna, Bologna (Italy); Brattich, E.; Cinelli, G. [Dipartimento di Chimica ' Giacomo Ciamician' , Laboratorio di Chimica Ambientale e Radioattivita and Dipartimento di Scienze della Terra e Geologico-Ambientali, Universita di Bologna, Bologna and (Italy)

    2013-07-15

    Measurements of airborne radionuclides {sup 7}Be ,{sup 210}Pb and PM{sub 10} have been routinely carried out together with aerosol mass concentration at theWMO-GAW station of Mt. Cimone (Northern Apennines, Italy) with the aim of obtaining basic information on aerosol behaviour at this site. Several years of data (the experimental activity was started in January 1998) are presented and discussed in this paper. Aerosol collection is carried out by filtration with a high volume PM{sub 10} sampler for 48 hours. Activities of {sup 7}Be and {sup 210}Pb were measured by non-destructive gray spectrometry and aerosol mass concentration was determined gravimetrically. A distinct seasonal cycle is observed for {sup 7}Be, {sup 210}Pb and PM{sub 10,} with maxima in the summer and minima in the winter. The opposite trend is observed for the activity ratio {sup 7}Be/{sup 210}Pb, used as an indicator of vertical transport. Variability of the three parameters at this site is discussed by means of statistical tools such as t-test analysis classification as well as by back trajectory approach. (author)

  14. Biologically produced sulfur

    NARCIS (Netherlands)

    Kleinjan, W.E.; Keizer, de A.; Janssen, A.J.H.

    2003-01-01

    Sulfur compound oxidizing bacteria produce sulfur as an intermediate in the oxidation of hydrogen sulfide to sulfate. Sulfur produced by these microorganisms can be stored in sulfur globules, located either inside or outside the cell. Excreted sulfur globules are colloidal particles which are

  15. Consumers and Producers

    NARCIS (Netherlands)

    E. Maira (Elisa)

    2018-01-01

    markdownabstractIn the last few decades, advances in information and communication technology have dramatically changed the way consumers and producers interact in the marketplace. The Internet and social media have torn down the information barrier between producers and consumers, leading to

  16. Producers and oil markets

    International Nuclear Information System (INIS)

    Greaves, W.

    1993-01-01

    This article attempts an assessment of the potential use of futures by the Middle East oil producers. It focuses on Saudi Arabia since the sheer size of Saudi Arabian sales poses problems, but the basic issues discussed are similar for the other Middle East producers. (Author)

  17. CNO and pep neutrino spectroscopy in Borexino: Measurement of the deep underground production of cosmogenic 11C in organic liquid scintillator

    OpenAIRE

    Borexino Collaboration

    2006-01-01

    Borexino is an experiment for low energy neutrino spectroscopy at the Gran Sasso underground laboratories. It is designed to measure the mono-energetic $^7$Be solar neutrino flux in real time, via neutrino-electron elastic scattering in ultra-pure organic liquid scintillator. Borexino has the potential to also detect neutrinos from the \\emph{pep} fusion process and the CNO cycle. For this measurement to be possible, radioactive contamination in the detector must be kept extremely low. Once su...

  18. Producing the Spielberg Brand

    OpenAIRE

    Russell, J.

    2016-01-01

    This chapter looks at the manufacture of Spielberg’s brand, and the limits of its usage. Spielberg’s directorial work is well known, but Spielberg’s identity has also been established in other ways, and I focus particularly on his work as a producer. At the time of writing, Spielberg had produced (or executive produced) 148 movies and television series across a range of genres that takes in high budget blockbusters and low budget documentaries, with many more to come. In these texts, Spielber...

  19. Preliminary study on 2-dimensional distributions of 10B reaction rate in a water phantom with boron-doped CR-39 for 7Li(p, n)7Be neutrons by 1.95 MeV protons

    International Nuclear Information System (INIS)

    Hasegawa, Y.; Tanaka, K.; Tsuruta, T.

    2000-01-01

    In an Accelerator-based neutron irradiation field using 7 Li(p, n) 7 Be neutrons by 1.95 MeV protons, the distributions of 10 B reaction rates and thermal neutron fluence in a water phantom were measured using Boron-doped CR-39 and Au activation analysis, respectively. Comparing the results of the measurements, we discussed the validity of the evaluation method of 10 B reaction rate using thermal neutron fluence. (author)

  20. Agricultural Producer Certificates

    Data.gov (United States)

    Montgomery County of Maryland — A Certified Agricultural Producer, or representative thereof, is an individual who wishes to sell regionally-grown products in the public right-of-way. A Certified...

  1. Methods for producing diterpenes

    DEFF Research Database (Denmark)

    2015-01-01

    The present invention discloses that by combining different di TPS enzymes of class I and class II different diterpenes may be produced including diterpenes not identified in nature. Surprisingly it is revealed that a di TPS enzyme of class I of one species may be combined with a di TPS enzyme...... of class II from a different species, resulting in a high diversity of diterpenes, which can be produced....

  2. Polysaccharide-producing microalgae

    Energy Technology Data Exchange (ETDEWEB)

    Braud, J.P.; Chaumont, D.; Gudin, C.; Thepenier, C.; Chassin, P.; Lemaire, C.

    1982-11-01

    The production of extracellular polysaccharides is studied with Nostoc sp (cyanophycus), Porphiridium cruentum, Rhodosorus marinus, Rhodella maculata (rhodophyci) and Chlamydomonas mexicana (chlorophycus). The polysaccharides produced are separated by centrifugation of the culture then precipitation with alcohol. Their chemical structure was studied by infrared spectrometry and acid hydrolysis. By their rheological properties and especially their insensitivity to temperatrure and pH variations the polysaccharides produced by Porphryridium cruentum and Rhodella maculata appear as suitable candidates for industrial applications.

  3. Producing metallurgic coke

    Energy Technology Data Exchange (ETDEWEB)

    Abe, T.; Isida, K.; Vada, Y.

    1982-11-18

    A mixture of power producing coals with coal briquets of varying composition is proposed for coking in horizontal chamber furnaces. The briquets are produced from petroleum coke, coal fines or semicoke, which make up less than 27 percent of the mixture to be briquetted and coals with a standard coking output of volatile substances and coals with high maximal Gizeler fluidity. The ratio of these coals in the mixture is 0.6 to 2.1 or 18 to 32 percent, respectively. Noncaking or poorly caking coals are used as the power producing coals. The hardness of the obtained coke is DJ15-30 = 90.5 to 92.7 percent.

  4. Experimental investigation of highly excited states of the 5,6He and 5,6Li nuclei in the (6Li, 7Be) and (6Li, 7Li) one-nucleon-pick-up reactions

    International Nuclear Information System (INIS)

    Sakuta, S.B.; Novatskij, B.G.; Stepanov, D.N.; Aleksandrov, D.V.; Glukhov, Yu.A.; Nikol'skij, E.Yu.

    2002-01-01

    ( 6 Li, 7 Be) and ( 6 Li, 7 Li) reactions on the 6 Li, 7 Li nuclei have been investigated in the angular range of 0-20 deg in laboratory system at the 93-MeV 6 Li energy. Besides low-lying states of 5,6 He and 5,6 Li nuclei, broad structures have been observed in the measured spectra close to the t( 3 He) + d and t( 3 He) + t threshold at excitation energies of 16.75 (3/2 + ) and ∼ 20 MeV ( 5 He), 16.66 (3/2 + ) and ∼ 20 MeV ( 5 Li), 14.0 and 25 MeV ( 6 He), and ∼ 20 MeV ( 6 Li). Angular distributions, which have been measured for transitions to the ground (0 + ) and exited states at E x =1.8 MeV (2 + ) and 14.0 MeV of the 6 He nucleus in the 7 Li( 6 Li, 7 Be) 6 He reaction, have been analyzed in the framework of the finite-range distorted-waves method assuming the 1p- and 1s-proton pick-up mechanism. It has been shown that ( 6 Li, 7 Be) and ( 6 Li, 7 Li) reactions predominately proceed by one-step pick-up mechanism and broad structures which are observed at high excitation energies should be considered as quasimolecular states of the t( 3 He) + d and t( 3 He) + t type [ru

  5. Effect of zirconium purity on the glass-forming-ability and notch toughness of Cu{sub 43}Zr{sub 43}Al{sub 7}Be{sub 7}

    Energy Technology Data Exchange (ETDEWEB)

    Andersen, Laura M. [Department of NanoEngineering, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA (United States); Hofmann, Douglas C. [Materials Development and Manufacturing Technology Group, NASA Jet Propulsion Laboratory/California Institute of Technology, MS 18-105, 4800 Oak Grove Dr. Pasadena, CA 91109 (United States); Vecchio, Kenneth S., E-mail: kvecchio@ucsd.edu [Department of NanoEngineering, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA (United States)

    2016-09-30

    The effect of substituting standard grade zirconium lump (99.8% excluding up to 4% hafnium) for high purity zirconium crystal bar (99.5%) in a Cu{sub 43}Zr{sub 43}Al{sub 7}Be{sub 7} bulk metallic glass (BMG) is examined. The final hafnium content in the BMG specimens was found to range from 0 to 0.44 at%. Introducing low purity zirconium significantly decreased the glass-forming-ability and reduced the notch toughness of the BMG. In contrast, when adding high purity hafnium to Cu{sub 43}Zr{sub 43}Al{sub 7}Be{sub 7} made with high purity zirconium, no significant change in the glass-forming-ability or toughness was observed. This suggests that the introduction of low purity zirconium in BMGs creates a more complex response than a simple addition of hafnium. It is likely that other impurities in the material, such as oxygen, play a role in the complex crystallization kinetics and change in mechanical properties. The notch toughness was measured through four-point-bend tests, which showed a decrease in notch toughness from an average of ~53 MPa m{sup 1/2} for the high purity samples to an average of ~29 MPa m{sup 1/2} with full substitution of low purity zirconium. A similar decrease in glass-forming-ability and toughness is observed in commercially synthesized high purity Cu{sub 43}Zr{sub 43}Al{sub 7}Be{sub 7}. The large scale commercial process is expected to introduced some unintentional impurities, which decrease the properties of the BMG in the same way as the lower purity elements. Lastly, Weibull statistics are used to provide an analysis of variability in toughness for both ingots synthesized in a small laboratory arc-melter and those synthesized commercially.

  6. Improved Results on Extraction of 11B(p, α0)8Be and 10B(p, α)7Be S(E)-Factor Through the Trojan Horse Method

    International Nuclear Information System (INIS)

    Puglia, S. M. R.; Lamia, L.; Romano, S.; Spitaleri, C.; Cherubini, S.; Gulino, M.; La Cognata, M.; Rapisarda, G. G.; Sergi, M. L.; Tudisco, S.; Carlin, N.; Del Santo, M. G.; Kroha, V.; Souza, F.; Szanto de Toledo, A.; Kubono, S.; Wakabayashi, Y.; Yamaguchi, H.; Li, C.; Qungang, W.

    2010-01-01

    In this work the analysis of the 10 B(23p, α) 7 Be and 11 B(p, α) 8 Be reactions, studied via the indirect Trojan Horse Method (THM), is discussed. In the astrophysical context of light nuclei LiBeB depletion, the above mentioned reactions are the main responsible for the destruction of boron in the stellar interior. The THM application allows their investigation in the astrophysically relevant energy region, around the Gamow Peak (≅10 keV), overcoming the problems due to the presence of the Coulomb barrier and electron screening effect. The experimental procedure and the preliminary results are shown.

  7. Standards and producers' liability

    International Nuclear Information System (INIS)

    Kretschmer, F.

    1979-01-01

    The author discusses the liability of producers and the diligence required, which has to come up to technical standards and the latest state of technology. The consequences of this requirement with regard to claims for damages are outlined and proposals for reforms are pointed out. (HSCH) [de

  8. Producing superhydrophobic roof tiles

    International Nuclear Information System (INIS)

    Carrascosa, Luis A M; Facio, Dario S; Mosquera, Maria J

    2016-01-01

    Superhydrophobic materials can find promising applications in the field of building. However, their application has been very limited because the synthesis routes involve tedious processes, preventing large-scale application. A second drawback is related to their short-term life under outdoor conditions. A simple and low-cost synthesis route for producing superhydrophobic surfaces on building materials is developed and their effectiveness and their durability on clay roof tiles are evaluated. Specifically, an organic–inorganic hybrid gel containing silica nanoparticles is produced. The nanoparticles create a densely packed coating on the roof tile surface in which air is trapped. This roughness produces a Cassie–Baxter regime, promoting superhydrophobicity. A surfactant, n-octylamine, was also added to the starting sol to catalyze the sol–gel process and to coarsen the pore structure of the gel network, preventing cracking. The application of ultrasound obviates the need to use volatile organic compounds in the synthesis, thereby making a ‘green’ product. It was also demonstrated that a co-condensation process effective between the organic and inorganic species is crucial to obtain durable and effective coatings. After an aging test, high hydrophobicity was maintained and water absorption was completely prevented for the roof tile samples under study. However, a transition from a Cassie–Baxter to a Wenzel state regime was observed as a consequence of the increase in the distance between the roughness pitches produced by the aging of the coating. (paper)

  9. Isotope shift measurements in the 2s(1/2) -> 2p(3/2) transition of Be+ and extraction of the nuclear charge radii for Be-7,Be-10,Be-11

    CERN Document Server

    Zakova, M; Yordanov, D T; Lochmann, M; Drake, G W F; Yan, Z-C; Neugart, R; Kowalska, M; Blaum, K; Andjelkovic, Z; Kraemer, J; Bissell, M L; Neff, T; Schmidt-Kaler, F; Sanchez, R; Noertershaeuser, W; Geppert, Ch; Tiedemann, D; Zimmermann, C

    2010-01-01

    We have performed isotope shift measurements in the 2s(1/2) -> 2p(3/2) transition of Be+ ions using advanced collinear laser spectroscopy with two counter-propagating laser beams. Measurements involving a frequency comb for laser stabilization and absolute frequency determination allowed us to determine the isotope shifts with an accuracy of 2 MHz. From the isotope shifts between Be-9 and Be-7,Be-10,Be-11, high-accuracy mass shift calculations and the charge radius of the reference isotope Be-9 we determined nuclear charge radii for the isotopes Be-7,Be-10 and the one-neutron halo nucleus Be-11. The results are compared to nuclear-structure calculations using the fermionic molecular dynamics model which reproduce well the general trend of the radii. Decreasing charge radii from Be-7 to Be-10 are explained by the cluster structure of the nuclei. The increase from Be-10 to Be-11 is mainly caused by the halo neutron by which the Be-10 core moves relative to the center of mass. Polarization of the Be-10 core has ...

  10. USA coal producer perspective

    Energy Technology Data Exchange (ETDEWEB)

    Porco, J. [Alpha Natural Resources, Latrobe, PA (US). Alpha Energy Global Marketing

    2004-07-01

    The focus is on the Central Appalachian coal industry. Alpha Natural Resources was formed in 2002 from Pittston Coal's Virginia and Coastal operations. AMCI's U.S. operations and Mears Enterprises in Pennsylvania were acquired later. The company produces 20-21 million tonnes per year and sells 20 million tonnes of steam coal and 10 million tonnes of exports, including some coal that is brokered. Foundry coke is a major product. Capital investment has resulted in increased productivity. Central Appalachia is expected to continue as a significant coal-producing region for supplying metallurgical coke. Production is expected to stabilize, but not increase; so the mines will have a longer life. 31 slides/overheads are included.

  11. Dimuons produced by antineutrinos

    International Nuclear Information System (INIS)

    Benvenuti, A.; Cline, D.; Ford, W.T.; Imlay, R.; Ling, T.Y.; Mann, A.K.; Orr, R.; Reeder, D.D.; Rubbia, C.; Stefanski, R.; Sulak, L.; Wanderer, P.

    1975-01-01

    In a run with a predominantly phi-bar beam we have observed seven dimuon events which show clearly that dimuons are produced by phi-bar as well as by phi. Using the signature of those events we tentatively identify twelve dimuon events from earlier runs as phi-bar-induced. The characteristics of the total sample support the explanation that dimuons arise from new hadron production

  12. Cluster model of A=7 nuclei revisited, and the astrophysical S factors for 3 He(α, γ)7 Be and 3 H(α, γ)7 Li at zero energy

    International Nuclear Information System (INIS)

    Buck, B.; Merchant, A.C.

    1988-10-01

    A elementary cluster model that visualizes an alpha particle interacting with a 3 H of 3 He cluster via a local potential is employed. An assurance is made that the major requirements of the Pauli principle are satisfied by choosing relative motion quantum numbers N (Principal Quantum Number) and L to correspond to the microscopic situation in which the 3 H or 3 He nucleons occupy shell-model orbitals above the (O ) - orbitals filled by the alpha particles. The S o factor for the capture reactions 3 He (α,γ) 7 Be and 3 H (α,γ) 7 Li is calculated by considering only electric dipole capture from incident s-waves as follows. (author)

  13. Producing quality radiographic images

    International Nuclear Information System (INIS)

    Cullinan, A.M.

    1987-01-01

    This book gives an overview of physics, equipment, imaging, and quality assurance in the radiology department. The chapters are laid out with generous use of subheads to allow for quick reference, Points are illustrated with clear, uncluttered line diagrams and well-produced images. The accompanying explanations are miniature lessons by themselves. Inserted at various points throughout the text are important notes that highlight key concepts. The chapter ''Image Evaluation and Application of Radiographic Principles'' present a systematic approach to evaluating radiographs and contains several sample radiographs to illustrate the points made

  14. Producing x-rays

    International Nuclear Information System (INIS)

    Mallozzi, P.J.; Epstein, H.M.; Jung, R.G.; Applebaum, D.C.; Fairand, B.P.; Gallagher, W.J.

    1977-01-01

    A method of producing x-rays by directing radiant energy from a laser onto a target is described. Conversion efficiency of at least about 3 percent is obtained by providing the radiant energy in a low-power precursor pulse of approximately uniform effective intensity focused onto the surface of the target for about 1 to 30 nanoseconds so as to generate an expanding unconfined coronal plasma having less than normal solid density throughout and comprising a low-density (underdense) region wherein the plasma frequency is less than the laser radiation frequency and a higher-density (overdense) region wherein the plasma frequency is greater than the laser radiation frequency and, about 1 to 30 nanoseconds after the precursor pulse strikes the target, a higher-power main pulse focused onto the plasma for about 10 -3 to 30 nanoseconds and having such power density and total energy that the radiant energy is absorbed in the underdense region and conducted into the overdense region to heat it and thus to produce x-rays therefrom with the plasma remaining substantially below normal solid density and thus facilitating the substantial emission of x-rays in the form of spectral lines arising from nonequilibrium ionization states

  15. Producing Civil Society

    DEFF Research Database (Denmark)

    Feldt, Liv Egholm; Hein Jessen, Mathias

    Since the beginning of the 1990’s, civil society has attracted both scholarly and political interest as the ‘third sphere’ outside the state and the market not only a normatively privileged site of communication and ‘the public sphere’, but also as a resource for democratization processes...... and social cohesion, as well as a provider of welfare services from a welfare state in dire straits. However, such a view upholds a sharp distinction between the three sectors and their distinct logic. This article claims that the separation of spheres is a fundamental part of our ‘social imaginary......’ and as such dominates our way of thinking about civil society. Yet, this view hinders the understanding of how civil society is not a pre-existing or given sphere, but a sphere which is constantly produced both discursively, conceptually and practically. Through two examples; 1,the case of philanthropy in the beginning...

  16. Cosmogenic He and Ne in chondrules from clastic matrix and a lithic clast of Murchison : No pre-irradiation by the early sun

    NARCIS (Netherlands)

    Riebe, My E.I.; Huber, Liliane; Metzler, Knut; Busemann, Henner; Luginbuehl, Stefanie M.; Meier, Matthias M.M.; Maden, Colin; Wieler, Rainer

    2017-01-01

    Whether or not some meteorites retain a record of irradiation by a large flux of energetic particles from the early sun in the form of excesses of cosmic-ray produced noble gases in individual crystals or single chondrules is a topic of ongoing debate. Here, we present He and Ne isotopic data for

  17. Power Producer Production Valuation

    Directory of Open Access Journals (Sweden)

    M. Kněžek

    2008-01-01

    Full Text Available The ongoing developments in the electricity market, in particular the establishment of the Prague Energy Exchange (PXE and the associated transfer from campaign-driven sale to continuous trading, represent a significant change for power companies.  Power producing companies can now optimize the sale of their production capacities with the objective of maximizing profit from wholesale electricity and supporting services. The Trading Departments measure the success rate of trading activities by the gross margin (GM, calculated by subtracting the realized sales prices from the realized purchase prices and the production cost, and indicate the profit & loss (P&L to be subsequently calculated by the Control Department. The risk management process is set up on the basis of a business strategy defining the volumes of electricity that have to be sold one year and one month before the commencement of delivery. At the same time, this process defines the volume of electricity to remain available for spot trading (trading limits. 

  18. Antibiotics produced by Streptomyces.

    Science.gov (United States)

    Procópio, Rudi Emerson de Lima; Silva, Ingrid Reis da; Martins, Mayra Kassawara; Azevedo, João Lúcio de; Araújo, Janete Magali de

    2012-01-01

    Streptomyces is a genus of Gram-positive bacteria that grows in various environments, and its shape resembles filamentous fungi. The morphological differentiation of Streptomyces involves the formation of a layer of hyphae that can differentiate into a chain of spores. The most interesting property of Streptomyces is the ability to produce bioactive secondary metabolites, such as antifungals, antivirals, antitumorals, anti-hypertensives, immunosuppressants, and especially antibiotics. The production of most antibiotics is species specific, and these secondary metabolites are important for Streptomyces species in order to compete with other microorganisms that come in contact, even within the same genre. Despite the success of the discovery of antibiotics, and advances in the techniques of their production, infectious diseases still remain the second leading cause of death worldwide, and bacterial infections cause approximately 17 million deaths annually, affecting mainly children and the elderly. Self-medication and overuse of antibiotics is another important factor that contributes to resistance, reducing the lifetime of the antibiotic, thus causing the constant need for research and development of new antibiotics. Copyright © 2012 Elsevier Editora Ltda. All rights reserved.

  19. Cyclotron produced radiopharmaceuticals

    International Nuclear Information System (INIS)

    Kopicka, K.; Fiser, M.; Hradilek, P.; Hanc, P.; Lebeda, O.

    2003-01-01

    Some of the cyclotron-produced radionuclides may serve as important materials for the production of radiopharmaceuticals. This lecture deals with basic information relating to various aspects of these compounds. In comparison with radionuclides /compounds used for non-medical purposes, radiopharmaceuticals are subject to a broader scale of regulations, both from the safety and efficacy point of view; besides that, there are both radioactive and medical aspects that must be taken into account for any radiopharmaceutical. According to the regulations and in compliance with general rules of work with radioactivity, radiopharmaceuticals should only be prepared/manufactured under special conditions, using special areas and special equipment and applying special procedures (e.g. sterilisation, disinfection, aseptic work). Also, there are special procedures for cleaning and maintenance. Sometimes the requirements for the product safety clash with those for the safety of the personnel; several examples of solutions pertaining to these cases are given in the lecture. Also, the specific role of cyclotron radiopharmaceuticals is discussed. (author)

  20. Radiation produced biomaterials

    International Nuclear Information System (INIS)

    Rosiak, J.M.

    1998-01-01

    radiation technique. Immobilization of biologically active species in hydrogel matrices, their use as drug delivery systems and enzyme traps as well as modification of material surfaces to improve their biocompatibility and ability to bond antigens and antibodies have been the main subject of their investigations. The rising interest in the field of application of radiation to bioengineering was also recognized by the International Atoimc Energy Agency, which has initiated the international programs relating to those studies. In these lectures some directions of investigations on the formation of hydrogels and their applications for biomedical purposes have been specified. Also, some examples of commercialized products being produced by means of radiation technique have been presented

  1. Seasonal variation in the environmental background level of cosmic ray produced 22Na

    International Nuclear Information System (INIS)

    Tokuyama, Hideki; Igarashi, Shuichi

    1998-01-01

    22 Na (half life 2.6 year) is produced by cosmic rays, nuclear test and reactor. 7 Be (half life 53.3 day) is produced in atmosphere by reaction. 7 Be/ 22 Na activity ratio is good factor to observe the mixing process between stratosphere and troposphere atmosphere. The seasonal variation of 7 Be and 22 Na deposition, the ratio and the background level of 22 Na deposition were observed in Fukui city and reported in this paper. Very large reasonable change of 22 Na deposition was observed, especially the largest peak in winter. Because the concentration of cosmic-ray-produced nuclear in precipitation and the amount of precipitation were large in winter. 22 Na produced by the previous nuclear test was attenuated. The present 22 Na is only produced by cosmic rays, indicating the background level. 22 Na deposition at Fukui was 0.42Bq m -2 y -1 , one ten-thousandth of 7 Be deposition. 7 Be/ 22 Na activity ratio was changed in season and the largest peak was shown in autumn. In this reason, atmosphere showed relatively short residence time in the lower part of stratosphere, Mixture and exchange of atmosphere between stratosphere and troposphere were the most active in autumn. (S.Y.)

  2. Indirect study of {sup 11}B(p,alpha{sub 0}){sup 8}Be and {sup 10}B(p,alpha){sup 7}Be reactions at astrophysical energies by means of the Trojan Horse Method: recent results

    Energy Technology Data Exchange (ETDEWEB)

    Lamia, L.; Puglia, S.M.R.; Spitaleri, C.; Romano, S. [Laboratori Nazionali del Sud, Catania (Italy); Dipartimento di Metodologie Fisiche e Chimiche per l' Ingegneria, Universita di Catania, Catania (Italy); Del Santo, M. Gimenez; Carlin, N.; Munhoz, M. Gameiro [Departamento de Fisica Nuclear, Universitade de Sao Paulo, Sao Paulo (Brazil); Cherubini, S. [Laboratori Nazionali del Sud, Catania (Italy); Dipartimento di Metodologie Fisiche e Chimiche per l' Ingegneria, Universita di Catania, Catania (Italy); Kiss, G.G. [Laboratori Nazionali del Sud, Catania (Italy); Atomki, Debrecen (Hungary); Kroha, V. [Institute for Nuclear Physics, Prague (Czech Republic); Kubono, S. [CNS, University of Tokyo, Tokyo (Japan); La Cognata, M. [Laboratori Nazionali del Sud, Catania (Italy); Dipartimento di Metodologie Fisiche e Chimiche per l' Ingegneria, Universita di Catania, Catania (Italy); Centro Siciliano di Fisica Nucleare e Struttura della Materia, Catania (Italy); Li Chengbo [China Institute of Atomic Energy, Department of Physics, Beijing (China); Pizzone, R.G. [Laboratori Nazionali del Sud, Catania (Italy); Dipartimento di Metodologie Fisiche e Chimiche per l' Ingegneria, Universita di Catania, Catania (Italy); Wen Qungang [China Institute of Atomic Energy, Department of Physics, Beijing (China); Sergi, M.L. [Laboratori Nazionali del Sud, Catania (Italy); Dipartimento di Metodologie Fisiche e Chimiche per l' Ingegneria, Universita di Catania, Catania (Italy); Centro Siciliano di Fisica Nucleare e Struttura della Materia, Catania (Italy); Szanto de Toledo, A. [Departamento de Fisica Nuclear, Universitade de Sao Paulo, Sao Paulo (Brazil); Wakabayashi, Y. [CNS, University of Tokyo, Tokyo (Japan); Advanced Science Research Center - JAEA - Ibaraki (Japan); Yamaguchi, H. [CNS, University of Tokyo, Tokyo (Japan); Zhou Shuhua [China Institute of Atomic Energy, Department of Physics, Beijing (China)

    2010-03-01

    Nuclear (p,alpha) reactions destroying the so-called 'light-elements' lithium, beryllium and boron have been largely studied in the past mainly because their role in understanding some astrophysical phenomena, i.e. mixing-phenomena occurring in young F-G stars [A.M. Boesgaard et al., Astr. Phys. J, 991, 2005, 621]. Such mechanisms transport the surface material down to the region close to the nuclear destruction zone, where typical temperatures of the order of approx10{sup 6} K are reached. The corresponding Gamow energy E{sub 0}=1.22(Z{sub x}{sup 2}Z{sub X}{sup 2}T{sub 6}{sup 2}){sup 1/3} keV [C. Rolfs and W. Rodney, 'Cauldrons in the Cosmos', The Univ. of Chicago press, 1988] is about approx10 keV if one considers the 'boron-case' and replaces in the previous formula Z{sub x}=1, Z{sub X}=5 and T{sub 6}=5. Direct measurements of the two {sup 11}B(p,alpha{sub 0}){sup 8}Be and {sup 10}B(p,alpha){sup 7}Be reactions in correspondence of this energy region are difficult to perform mainly because the combined effects of Coulomb barrier penetrability and electron screening [H.J. Assenbaum, K. Langanke and C. Rolfs, Z. Phys., 327, 1987, 461]. The indirect method of the Trojan Horse (THM) [G. Baur et al., Phys. Lett. B, 178, 1986, 135; G. Calvi et al., Nucl. Phys. A, 621, 1997, 139; C. Spitaleri et al., Phys. Rev. C, 493, 1999, 206] allows one to extract the two-body reaction cross section of interest for astrophysics without the extrapolation-procedures. Due to the THM formalism, the extracted indirect data have to be normalized to the available direct ones at higher energies thus implying that the method is a complementary tool in solving some still open questions for both nuclear and astrophysical issues [S. Cherubini et al., Astr. Phys. J, 457, 1996, 855; C. Spitaleri et al., Phys. Rev. C, 63, 2001, 005801; C. Spitaleri et al., Phys. Rev. C, 63, 2004, 055806; A. Tumino et al., Phys. Rev. Lett., 98, 2007, 252502; M. La Cognata et al., Phys

  3. Producers give prices a boost

    International Nuclear Information System (INIS)

    Anon.

    1992-01-01

    Uranium producers came alive in August, helping spot prices crack the $8.00 barrier for the first time since March. The upper end of NUKEM's price range actually finished the month at $8.20. Scrambling to fulfill their long-term delivery contracts, producers dominate the market. In the span of three weeks, five producers came out for 2 million lbs U3O8, ultimately buying nearly 1.5 million lbs. One producer accounted for over half this volume. The major factor behind rising prices was that producers required specific origins to meet contract obligations. Buyers willing to accept open origins created the lower end of NUKEM's price range

  4. Predicted versus observed cosmic-ray-produced noble gases in lunar samples: improved Kr production ratios

    International Nuclear Information System (INIS)

    Regnier, S.; Hohenberg, C.M.; Marti, K.; Reedy, R.C.

    1979-01-01

    New sets of cross sections for the production of krypton isotopes from targets of Rb, Sr, Y, and Zr were constructed primarily on the bases of experimental excitation functions for Kr production from Y. These cross sections were used to calculate galactic-cosmic-ray and solar-proton production rates for Kr isotopes in the moon. Spallation Kr data obtained from ilmenite separates of rocks 10017 and 10047 are reported. Production rates and isotopic ratios for cosmogenic Kr observed in ten well-documented lunar samples and in ilmenite separates and bulk samples from several lunar rocks with long but unknown irradiation histories were compared with predicted rates and ratios. The agreements were generally quite good. Erosion of rock surfaces affected rates or ratios for only near-surface samples, where solar-proton production is important. There were considerable spreads in predicted-to-observed production rates of 83 Kr, due at least in part to uncertainties in chemical abundances. The 78 Kr/ 83 Kr ratios were predicted quite well for samples with a wide range of Zr/Sr abundance ratios. The calculated 80 Kr/ 83 Kr ratios were greater than the observed ratios when production by the 79 Br(n,γ) reaction was included, but were slightly undercalculated if the Br reaction was omitted; these results suggest that Br(n,γ)-produced Kr is not retained well by lunar rocks. The productions of 81 Kr and 82 Kr were overcalculated by approximately 10% relative to 83 Kr. Predicted-to-observed 84 Kr/ 83 ratios scattered considerably, possibly because of uncertainties in corrections for trapped and fission components and in cross sections for 84 Kr production. Most predicted 84 Kr and 86 Kr production rates were lower than observed. Shielding depths of several Apollo 11 rocks were determined from the measured 78 Kr/ 83 Kr ratios of ilmenite separates. 4 figures, 5 tables

  5. Galactic cosmic-ray-produced radionuclides in Antarctic meteorites and a lunar core

    International Nuclear Information System (INIS)

    Fox, R.L.

    1987-01-01

    Radionuclide depth effects in a meteorite, the history and pairing of Antarctic meteorites and processes on the lunar surface are discussed in six chapters. A depth profile of 26 Al, 10 Be and 53 Mn activities have been measured in eleven metal phase samples of the Antarctic meteorite ALHA78084 to determine the importance of the secondary cascade in producing these nuclides in a 30 centimeter diameter meteorite. The results show a buildup of lower energy reaction products and a flat profile for high energy reaction products with depth. The activity of 53 Mn has been measured as a function of depth in eleven soil samples from the lunar double drive tubes 15011/15010. The results agree within error with the previous results of Nishiizumi. These data are consistent with the previously published 26 Al results of the Battelle Northwest group which indicated a disturbed profile down to 17 g/cm 2 and an accumulation rate of 2 cm/My. Comparison with the gardening models of Arnold and Langevin and the local topography suggests such a continuous accumulation is the result of steady downslope transport of surface soil for 7 to 10 My at this site. The 53 Mn activity was determined in eleven samples in eight Allan Hills-80 Antarctic meteorites and one sample from an Elephant Moraine Antarctic meteorite. Mineralogic and field relation data suggest that Allan Hills meteorites to be two sets of paired falls. The 53 Mn results are consistent with the grouping of these meteorites as paired falls excluding the meteorite ALHA80127. comparison with future nuclear particle track work and results from the measurement of other cosmogenic nuclides will provide more definitive results

  6. Cosmogenic 35S as a Novel Detector of Stratospheric Air at the Earth's Surface: Key Findings from the Western United States and New Insights into the Seasonal Variations of Ozone and Sulfate in East Asia

    Science.gov (United States)

    Lin, M.; Thiemens, M. H.; Shaheen, R.; Biglari, S.; Crocker, D.; Zhang, Z.; Tao, J.; Su, L.; Fung, J. C. H.; Su, B.; Liu, L.

    2016-12-01

    The extent to which stratospheric intrusions on synoptic scales influence the tropospheric ozone (O3) levels remains poorly understood because quantitative detection of stratosphere air at the Earth's surface has been challenging. Cosmogenic 35S is invaluable in such quantification, but this has not yet been unambiguously demonstrated. As a global hot spot for stratospheric intrusions, the western United States (US) is a natural laboratory for testing the validity of this approach. Here, we present measurements of 35S in sulfate aerosols during a well-defined deep stratospheric intrusion event in the western US, which led to a regional O3 pollution event across southern California. The surprisingly high 35S activity in this episode is greater than any other natural radiogenic sulfate aerosols reported in the literature, providing the first and direct field-based evidence that 35S is a sensitive tracer for air mass of stratospheric origin and transported downward. Using this novel tracer, we quantify the seasonal variation for the strength of downward transport of stratospheric air to the planetary boundary layer in East Asia (EA) and what it may mean for surface O3 and sulfate levels. Our 35S measurements in sulfate aerosols collected from a background site (Mount Wuyi; 27.72°N, 117.68°E) during 2014-2015 show peaks in spring and autumn and the temporal variations of 35S were in tandem with surface O3 levels. These results imply that stratospheric O3 in aged stratospheric air masses may contribute to surface O3 levels in the study region in these two seasons. Along with radiogenic 35S analysis, measuring all seven stable isotopes (16O, 17O, 18O, 32S, 33S, 34S and 36S) in the same sulfate samples provides significantly deeper understanding of the atmospheric sulfur cycle in this region. Triple oxygen isotopes are being measured and preliminary results show that the relative importance of different formation pathways of secondary sulfate in EA is likely altitude

  7. [Distiller Yeasts Producing Antibacterial Peptides].

    Science.gov (United States)

    Klyachko, E V; Morozkina, E V; Zaitchik, B Ts; Benevolensky, S V

    2015-01-01

    A new method of controlling lactic acid bacteria contamination was developed with the use of recombinant Saccharomyces cerevisiae strains producing antibacterial peptides. Genes encoding the antibacterial peptides pediocin and plantaricin with codons preferable for S. cerevisiae were synthesized, and a system was constructed for their secretory expression. Recombinant S. cerevisiae strains producing antibacterial peptides effectively inhibit the growth of Lactobacillus sakei, Pediacoccus pentasaceus, Pediacoccus acidilactici, etc. The application of distiller yeasts producing antibacterial peptides enhances the ethanol yield in cases of bacterial contamination. Recombinant yeasts producing the antibacterial peptides pediocin and plantaricin can successfully substitute the available industrial yeast strains upon ethanol production.

  8. A method of producing hydroxymethyfurfural

    DEFF Research Database (Denmark)

    2011-01-01

    The present invention relates to a method of producing 5-hydroxymethylfurfural by dehydration of fructose and/or glucose and/or mannose.......The present invention relates to a method of producing 5-hydroxymethylfurfural by dehydration of fructose and/or glucose and/or mannose....

  9. Producers' Complex Risk Management Choices

    NARCIS (Netherlands)

    Pennings, J.M.E.; Isengildina, O.; Irwin, S.H.; Garcia, P.; Good, D.L.

    2008-01-01

    Producers have a wide variety of risk management instruments available, making their choice(s) complex. The way producers deal with this complexity can vary and may influence the impact that the determinants, such as risk aversion, have on their choices. A recently developed choice bracketing

  10. Method of producing molybdenum-99

    Science.gov (United States)

    Pitcher, Eric John

    2013-05-28

    Method of producing molybdenum-99, comprising accelerating ions by means of an accelerator; directing the ions onto a metal target so as to generate neutrons having an energy of greater than 10 MeV; directing the neutrons through a converter material comprising techentium-99 to produce a mixture comprising molybdenum-99; and, chemically extracting the molybdenum-99 from the mixture.

  11. Tekna's produced water conference 2005

    International Nuclear Information System (INIS)

    2005-01-01

    The conference has 22 presentations discussing topics on discharge reduction, produced water quality, produced water re-injection, chemicals particularly environmentally friendly ones, separation technology, reservoir souring, total water management systems, pollution, oil in water problems and platform operation. Various field tests and experiences particularly from the offshore petroleum sector are presented (tk)

  12. DOES ELECTRIC CAR PRODUCE EMISSIONS?

    Directory of Open Access Journals (Sweden)

    Vladimír RIEVAJ

    2017-03-01

    Full Text Available This article focuses on the comparison of the amount of emissions produced by vehicles with a combustion engine and electric cars. The comparison, which is based on the LCA factor results, indicates that an electric car produces more emissions than a vehicle with combustion engine. The implementation of electric cars will lead to an increase in the production of greenhouse gases.

  13. Producing colour pictures from SCAN

    International Nuclear Information System (INIS)

    Robichaud, K.

    1982-01-01

    The computer code SCAN.TSK has been written for use on the Interdata 7/32 minicomputer which will convert the pictures produced by the SCAN program into colour pictures on a colour graphics VDU. These colour pictures are a more powerful aid to detecting errors in the MONK input data than the normal lineprinter pictures. This report is intended as a user manual for using the program on the Interdata 7/32, and describes the method used to produce the pictures and gives examples of JCL, input data and of the pictures that can be produced. (U.K.)

  14. Producing new radionuclides for medicine

    International Nuclear Information System (INIS)

    Michaut, C.

    2009-01-01

    The Arronax cyclotron, a new particle accelerator dedicated to the production of radionuclides for medicine and research has been commissioned in Nantes (France). Because of its unique features: an energy of 70 MeV and an intensity of 750 μA, Arronax will produce radionuclides that can not be produce in present cyclotrons. Among others it will produce Strontium-82 and Germanium-68 that are the precursors for Rubidium-82 and Gallium-68 respectively. 20 per cent of the research works will be dedicated to other domains like radioactive wastes, the radiation biological damage and the radiation damage on electronic devices. (A.C.)

  15. Cellulase producing microorganism ATCC 55702

    Science.gov (United States)

    Dees, H. Craig

    1997-01-01

    Bacteria which produce large amounts of cellulase--containing cell-free fermentate have been identified. The original bacterium (ATCC 55703) was genetically altered using nitrosoguanidine (MNNG) treatment to produce the enhanced cellulase producing bacterium (ATCC 55702), which was identified through replicate plating. ATCC 55702 has improved characteristics and qualifies for the degradation of cellulosic waste materials for fuel production, food processing, textile processing, and other industrial applications. ATCC 55702 is an improved bacterial host for genetic manipulations using recombinant DNA techniques, and is less likely to destroy genetic manipulations using standard mutagenesis techniques.

  16. Methods of producing cesium-131

    Science.gov (United States)

    Meikrantz, David H; Snyder, John R

    2012-09-18

    Methods of producing cesium-131. The method comprises dissolving at least one non-irradiated barium source in water or a nitric acid solution to produce a barium target solution. The barium target solution is irradiated with neutron radiation to produce cesium-131, which is removed from the barium target solution. The cesium-131 is complexed with a calixarene compound to separate the cesium-131 from the barium target solution. A liquid:liquid extraction device or extraction column is used to separate the cesium-131 from the barium target solution.

  17. Methods of producing transportation fuel

    Science.gov (United States)

    Nair, Vijay [Katy, TX; Roes, Augustinus Wilhelmus Maria [Houston, TX; Cherrillo, Ralph Anthony [Houston, TX; Bauldreay, Joanna M [Chester, GB

    2011-12-27

    Systems, methods, and heaters for treating a subsurface formation are described herein. At least one method for producing transportation fuel is described herein. The method for producing transportation fuel may include providing formation fluid having a boiling range distribution between -5.degree. C. and 350.degree. C. from a subsurface in situ heat treatment process to a subsurface treatment facility. A liquid stream may be separated from the formation fluid. The separated liquid stream may be hydrotreated and then distilled to produce a distilled stream having a boiling range distribution between 150.degree. C. and 350.degree. C. The distilled liquid stream may be combined with one or more additives to produce transportation fuel.

  18. Cosmogenic radioisotopes in Gebel Kamil meteorite

    Science.gov (United States)

    Taricco, C.; Colombetti, P.; Bhandari, N.; Sinha, N.; Di Martino, M.; Vivaldo, G.

    2012-04-01

    Recently a small (45 m in diameter) and very young (radioisotope activity generated by cosmic rays in the meteoroids as they travel through the interplanetary space before falling on the Earth. From the 26Al activity measurement and its depth production profiles, we infer (i) that the radius of the meteoroid should be about 1 m, constraining to 30-40 ton the range of pre-atmospheric mass previously proposed and (ii) that the fragment should have been located deeply inside the meteoroid, at a depth > 0.7 m. The 44Ti activity is under the detection threshold of the apparatus; using the depth production profiles of this radioisotope and its half-life T1/2 = 59.2 y, we deduce an upper limit to the date of fall.

  19. Cosmogenic photons strongly constrain UHECR source models

    Directory of Open Access Journals (Sweden)

    van Vliet Arjen

    2017-01-01

    Full Text Available With the newest version of our Monte Carlo code for ultra-high-energy cosmic ray (UHECR propagation, CRPropa 3, the flux of neutrinos and photons due to interactions of UHECRs with extragalactic background light can be predicted. Together with the recently updated data for the isotropic diffuse gamma-ray background (IGRB by Fermi LAT, it is now possible to severely constrain UHECR source models. The evolution of the UHECR sources especially plays an important role in the determination of the expected secondary photon spectrum. Pure proton UHECR models are already strongly constrained, primarily by the highest energy bins of Fermi LAT’s IGRB, as long as their number density is not strongly peaked at recent times.

  20. On the feasibility of producing secondary radioactive nuclear beams using reactions in reversed geometries at HI-13 tandem accelerator

    International Nuclear Information System (INIS)

    Bai Xixiang; Liu Weiping

    1993-01-01

    Some of (p,n),(d,p),(d,n) and (d, 3 He) reactions involving heavy-ions in reversed geometries are proposed for producing the kinematically compressed beams of ions such as 6 He, 7 Be, 8 Li, 11 C, 12 B, 13 N, 15 O and 17 F. A simple facility being constructed to produce and utilize these beams is briefly described

  1. Preliminary study of 7Be concentration in environmental (air) samples

    International Nuclear Information System (INIS)

    Quintero P, E.; Rojas M, V.P.; Alfaro L, M.M.; Cervantes N, M.L.; Gaso P, M.I.

    2001-01-01

    In this work lithium silicates were synthesised by the combustion technique, the mixtures were prepared with different molar ratios and using urea as fuel. Its characterization was realized by means of X-ray diffraction (XRD) and the percentages of its sizes were determined measuring the area under curve of the peaks in the diffractogram. (Author)

  2. Constraints on ice volume changes of the WAIS and Ross Ice Shelf since the LGM based on cosmogenic exposure ages in the Darwin-Hatherton glacial system of the Transantarctic Mountains

    Science.gov (United States)

    Fink, David; Storey, Bryan; Hood, David; Joy, Kurt; Shulmeister, James

    2010-05-01

    Quantitative assessment of the spatial and temporal scale of ice volume change of the West Antarctic ice sheet (WAIS) and Ross Ice Shelf since the last glacial maximum (LGM) ~20 ka is essential to accurately predict ice sheet response to current and future climate change. Although global sea level rose by approximately 120 metres since the LGM, the contribution of polar ice sheets is uncertain and the timing of any such contribution is controversial. Mackintosh et al (2007) suggest that sectors of the EAIS, similar to those studied at Framnes Mountains where the ice sheet slowly calves at coastal margins, have made marginal contributions to global sea-level rise between 13 and 7 ka. In contrast, Stone et al (2003) document continuing WAIS decay during the mid-late Holocene, raising the question of what was the response of the WAIS since LGM and into the Holocene. Terrestrial evidence is restricted to sparse coastal oasis and ice free mountains which archive limits of former ice advances. Mountain ranges flanking the Darwin-Hatherton glaciers exhibit well-defined moraines, weathering signatures, boulder rich plateaus and glacial tills, which preserve the evidence of advance and retreat of the ice sheet during previous glacial cycles. Previous studies suggest a WAIS at the LGM in this location to be at least 1,000 meters thicker than today. As part of the New Zealand Latitudinal Gradient Project along the Transantarctic, we collected samples for cosmogenic exposure dating at a) Lake Wellman area bordering the Hatherton Glacier, (b) Roadend Nunatak at the confluence of the Darwin and Hatherton glaciers and (c) Diamond Hill which is positioned at the intersection of the Ross Ice Shelf and Darwin Glacier outlet. While the technique of exposure dating is very successful in mid-latitude alpine glacier systems, it is more challenging in polar ice-sheet regions due to the prevalence of cold-based ice over-riding events and absence of outwash processes which removes

  3. Origin and transport of sediments in an alpine glaciated catchment (Bossons glacier, France): a quantification combining hydro-sedimentary data, radio-frequency identification of pebbles, cosmogenic nuclides content and probabilistic methods

    International Nuclear Information System (INIS)

    Guillon, Herve

    2016-01-01

    Among the most efficient agents of erosion, glaciers react dynamically to climate change, leading to a significant adjustment of downstream sediment flux. Present-day global warming raises the question regarding the evolution of the sediment load originating from partially glaciated catchment. The detrital export from such environment results from erosion processes operating within distinct geomorphologic domains: supra-glacial rock-walls, ice-covered substratum and the pro-glacial area, downstream from the glacier. The general intent of this doctoral research is therefore to characterize the origin and transport of sediments in the watersheds of two streams draining Bossons glacier (Mont-Blanc massif, France).For this purpose, the components of the sediment flux coming from supra-glacial, sub-glacial and pro-glacial domains are separated and quantified by innovating methods: i. Using the terrestrial cosmogenic nuclides concentrations as evidence of a supra-glacial transport; ii. Combining meteorological data and hydro-sedimentary data acquired at a high time resolution (2 min) and completed by multi-linear models; iii. Estimating sediment flux by source for 7 years and with a probabilistic method; iv. Associating radio-frequency identification of pebbles in the pro-glacial area with a stochastic transport analysis.Through numerical tools, applying the presented methodologies provides erosion rates of the supra-glacial, sub-glacial and pro-glacial domains, and determines the sediment transfer mechanisms within the catchment.Thus in the terminal part of the glacier, 52±14 to 9±4% of the supra-glacial load is transferred to the sub-glacial drainage network. Moreover, its evolution throughout the melt season leads to the export of the winter sediment production during a limited period. Furthermore, the drainage configuration beneath the glacier and its retreat control the remobilization of a long-term sediment stock. These processes explain the contrast between the

  4. Price satisfaction and producer loyalty

    DEFF Research Database (Denmark)

    Mutonyi, Sarah; Beukel, Karin; Gyau, Amos

    2016-01-01

    Purpose The purpose of this paper is to investigate which dimensions of price satisfaction influence producers’ trust in buyers and assess the mediating role of such trust in the relationship between price satisfaction and producer loyalty in fresh fruit supply chains. Design/methodology/approach......Purpose The purpose of this paper is to investigate which dimensions of price satisfaction influence producers’ trust in buyers and assess the mediating role of such trust in the relationship between price satisfaction and producer loyalty in fresh fruit supply chains. Design...... reliability, and relative price are dimensions of price satisfaction that affect producers’ trust in the buyer. Moreover, trust between the producer and the buyer is found to be a strong mediator between price satisfaction and producer loyalty. The findings support recent studies about trust and its mediating...... between the multi-dimensional nature of price satisfaction and producer loyalty with trust as a mediating variable in the business-to-business (B2B) context. Although B2B relationships have been shown to be of great importance for smallholders in enhancing business performance with their buyers, little...

  5. Producing liquid fuels from biomass

    Science.gov (United States)

    Solantausta, Yrjo; Gust, Steven

    The aim of this survey was to compare, on techno-economic criteria, alternatives of producing liquid fuels from indigenous raw materials in Finland. Another aim was to compare methods under development and prepare a proposal for steering research related to this field. Process concepts were prepared for a number of alternatives, as well as analogous balances and production and investment cost assessments for these balances. Carbon dioxide emissions of the alternatives and the price of CO2 reduction were also studied. All the alternatives for producing liquid fuels from indigenous raw materials are utmost unprofitable. There are great differences between the alternatives. While the production cost of ethanol is 6 to 9 times higher than the market value of the product, the equivalent ratio for substitute fuel oil produced from peat by pyrolysis is 3 to 4. However, it should be borne in mind that the technical uncertainties related to the alternatives are of different magnitude. Production of ethanol from barley is of commercial technology, while biomass pyrolysis is still under development. If the aim is to reach smaller carbon dioxide emissions by using liquid biofuels, the most favorable alternative is pyrolysis oil produced from wood. Fuels produced from cultivated biomass are more expensive ways of reducing CO2 emissions. Their potential of reducing CO2 emissions in Finland is insignificant. Integration of liquid fuel production to some other production line is more profitable.

  6. Human body may produce bacteria.

    Science.gov (United States)

    Salerian, Alen J

    2017-06-01

    "Human body may produce bacteria" proposes that human body may produce bacteria and represent an independent source of infections contrary to the current paradigm of infectious disorders proposed by Louis Pasteur in 1880. The following observations are consistent with this hypothesis: A. Bidirectional transformations of both living and nonliving things have been commonly observed in nature. B. Complex multicellular organisms harbor the necessary properties to produce bacteria (water, nitrogen and oxygen). C. Physical laws suggest any previously observed phenomenon or action will occur again (life began on earth; a non living thing). D. Animal muscle cells may generate energy (fermentation). E. Sterilized food products (i.e. boiled eggs), may produce bacteria and fungus under special conditions and without any exposure to foreign living cells. "Human body may produce bacteria" may challenge the current medical paradigm that views human infectious disorders as the exclusive causative byproducts of invading foreign cells. It may also introduce new avenues to treat infectious disorders. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Produced water - composition and analysis

    International Nuclear Information System (INIS)

    Kvernheim, Arne Lund

    1998-01-01

    Produced water can be defined as ''High volume waste-water separated from oil and gas that is produced from subsurface formations''. The water contains aliphatic and aromatic hydrocarbons, particulate matter and soluble salts as well as elements originating from formations and from sea water injections. Residues of chemicals may also be present. The accepted North Sea discharge limit is 40 ppm. In this presentation the focus will be on the chemical composition of produced water and on the challenges involved in developing and implementing analytical methods. The focus will also be on the development of a new oil-in-water analytical method as a replacement for the Freon method. 7 refs., 1 tab

  8. Method of producing grouting mortar

    Energy Technology Data Exchange (ETDEWEB)

    Shelomov, I K; Alchina, S I; Dizer, E I; Gruzdeva, G A; Nikitinskii, V I; Sabirzyanov, A K

    1980-10-07

    A method of producing grouting mortar by mixing the cement with an aqueous salt solution is proposed. So as to increase the quality of the mortar through an acceleration of the time for hardening, the mixture is prepared in two stages, in the first of which 20-30% of the entire cement batch hardens, and in the second of which the remainder of the cement hardens; 1-3-% of an aqueous salt solution is used in quantities of 0.5/1 wt.-% of weight of the cement. The use of this method of producing grouting mortar helps to increase the flexural strength of the cement brick up to 50% after two days ageing by comparison with the strength of cement brick produced from grouting mortar by ordinary methods utilizing identical quantities of the initial components (cement, water, chloride).

  9. Apparatus for producing laser targets

    International Nuclear Information System (INIS)

    Jarboe, T.R.; Baker, W.R.

    1975-01-01

    This patent relates to an apparatus and method for producing deuterium targets or pellets of 25u to 75u diameter. The pellets are sliced from a continuously spun solid deuterium thread at a rate of up to 10 pellets/second. The pellets after being sliced from the continuous thread of deuterium are collimated and directed to a point of use, such as a laser activated combustion or explosion chamber wherein the pellets are imploded by laser energy or laser produced target plasmas for neutral beam injection

  10. Producing deep-water hydrocarbons

    International Nuclear Information System (INIS)

    Pilenko, Thierry

    2011-01-01

    Several studies relate the history and progress made in offshore production from oil and gas fields in relation to reserves and the techniques for producing oil offshore. The intention herein is not to review these studies but rather to argue that the activities of prospecting and producing deep-water oil and gas call for a combination of technology and project management and, above all, of devotion and innovation. Without this sense of commitment motivating men and women in this industry, the human adventure of deep-water production would never have taken place

  11. Method for producing redox shuttles

    Science.gov (United States)

    Pupek, Krzysztof Z.; Dzwiniel, Trevor L.; Krumdick, Gregory K.

    2015-03-03

    A single step method for producing a redox shuttle having the formula 2,5-di-tert-butyl-1,4-phenylene tetraethyl bis(phosphate) is provided, the method comprising phosphorylating tert butyl hydroquinone with a phosphate-containing reagent. Also provided is method for producing 2,5-di-tert-butyl-1,4-phenylene tetraethyl bis(phosphate), the method comprising solubilizing tert-butyl hydroquinone and tetrabutylammonium bromide with methyltetrahydrofuran to create a mixture; heating the mixture while adding base to the mixture in an amount to turn the mixture orange; and adding diethyl chlorophosphate to the orange mixture in an amount to phosphorylate the hydroquinone.

  12. Marketing Hardwoods to Furniture Producers

    Science.gov (United States)

    Steven A. Sinclair; Robert J. Bush; Philip A. Araman

    1989-01-01

    This paper discusses some of the many problems in developing marketing programs for small wood products manufacturers. It examines the problems of using price as a dominant means for getting and attracting customers. The marketing of hardwood lumber to furniture producers is then used as an example. Data from 36 furniture lumber buyers is presented to illustrate...

  13. Importance of producing impactful research

    CSIR Research Space (South Africa)

    Nienaber, S

    2010-11-01

    Full Text Available from the more pragmatic issue of funding. Funding agencies, organisational leadership and policymakers need scientists to prove that the science we produce makes enough of an impact to merit further funding in future. This emphasis and pressure around...

  14. Method of producing vegetable puree

    DEFF Research Database (Denmark)

    2004-01-01

    A process for producing a vegetable puree, comprising the sequential steps of: a)crushing, chopping or slicing the vegetable into pieces of 1 to 30 mm; b) blanching the vegetable pieces at a temperature of 60 to 90°C; c) contacted the blanched vegetable pieces with a macerating enzyme activity; d......) blending the macerated vegetable pieces and obtaining a puree....

  15. Cosmic ray exposure dating of geo-morphic surface features using in situ-produced 10Be: tectonic and climatic implications

    International Nuclear Information System (INIS)

    Siame, L.; Bellier, O.; Sebrier, M.; Braucher, R.; Bourles, D.L.

    2001-01-01

    The evolution of continental landforms is mainly modulated by the impact of climatic and tectonic processes. Because of their distinctive morphology and the periodicity of their deposition, climatically induced landforms such as alluvial fans or terraces are well suited to infer rates of tectonic and continental climatic processes. Within tectonically active regions, an important step consists in dating displaced geomorphic features to calculate slip rates on active faults. Dating is probably the most critical tool because it is generally much more simpler to measure deformation resulting from tectonic activity than it is to accurately date when that deformation occurred. Recent advances in analytical chemistry and nuclear physics (accelerator mass spectrometry) now allow quantitative abundance measurements of the extremely rare isotopes produced by the interaction of cosmic rays with surface rocks and soils, the so-called in situ-produced cosmogenic nuclides ( 3 He, 10 Be, 21 Ne, 26 Al, 36 Cl), and allow to directly date the duration that a landform has been exposed to cosmic rays at the Earth's surface (Lal, 1991; Nishiizumi et al., 1993; Cerling and Craig, 1994; Clark et al., 1995]. In fact, the abundance of these cosmo-nuclides is proportional to landscape stability and, under favorable circumstances, their abundance within surface rocks can be used as a proxy for erosion rate or exposure age. These cosmo-nuclides thus provide geomorphologists with the opportunity to constrain rates of landscape evolution. This paper presents a new approach that combines cosmic ray exposure (CRE) dating using in situ-produced 10 Be and geomorphic as well as structural analyse. This approach has been applied on two active strike-slip and reverse faults located in the Andean fore-land of western Argentina. These two case studies illustrate how CRE dating using in situ-produced 10 Be is particularly well suited for geomorphic studies that aim to estimate the respective control of

  16. Method for producing carbon nanotubes

    Science.gov (United States)

    Phillips, Jonathan [Santa Fe, NM; Perry, William L [Jemez Springs, NM; Chen, Chun-Ku [Albuquerque, NM

    2006-02-14

    Method for producing carbon nanotubes. Carbon nanotubes were prepared using a low power, atmospheric pressure, microwave-generated plasma torch system. After generating carbon monoxide microwave plasma, a flow of carbon monoxide was directed first through a bed of metal particles/glass beads and then along the outer surface of a ceramic tube located in the plasma. As a flow of argon was introduced into the plasma through the ceramic tube, ropes of entangled carbon nanotubes, attached to the surface of the tube, were produced. Of these, longer ropes formed on the surface portion of the tube located in the center of the plasma. Transmission electron micrographs of individual nanotubes revealed that many were single-walled.

  17. Nonlinear Pricing to Produce Information

    OpenAIRE

    David J. Braden; Shmuel S. Oren

    1994-01-01

    We investigate the firm's dynamic nonlinear pricing problem when facing consumers whose tastes vary according to a scalar index. We relax the standard assumption that the firm knows the distribution of this index. In general the firm should determine its marginal price schedule as if it were myopic, and produce information by lowering the price schedule; “bunching” consumers at positive purchase levels should be avoided. As a special case we also consider a market characterized by homogeneous...

  18. Method for producing metallic nanoparticles

    Science.gov (United States)

    Phillips, Jonathan; Perry, William L.; Kroenke, William J.

    2004-02-10

    Method for producing metallic nanoparticles. The method includes generating an aerosol of solid metallic microparticles, generating non-oxidizing plasma with a plasma hot zone at a temperature sufficiently high to vaporize the microparticles into metal vapor, and directing the aerosol into the hot zone of the plasma. The microparticles vaporize in the hot zone to metal vapor. The metal vapor is directed away from the hot zone and to the plasma afterglow where it cools and condenses to form solid metallic nanoparticles.

  19. Method for producing metallic microparticles

    Science.gov (United States)

    Phillips, Jonathan; Perry, William L.; Kroenke, William J.

    2004-06-29

    Method for producing metallic particles. The method converts metallic nanoparticles into larger, spherical metallic particles. An aerosol of solid metallic nanoparticles and a non-oxidizing plasma having a portion sufficiently hot to melt the nanoparticles are generated. The aerosol is directed into the plasma where the metallic nanoparticles melt, collide, join, and spheroidize. The molten spherical metallic particles are directed away from the plasma and enter the afterglow where they cool and solidify.

  20. Extended producer responsibility in oligopoly

    OpenAIRE

    Hiroaki Ino

    2007-01-01

    I investigate the optimal environmental tax under a policy based on extended producer responsibility (EPR) in oligopoly markets. I introduce the recycling market and explicitly consider how these policies affect the incentive for recycling. I derive the optimal tax rule, which depends on the weighted sum of the markup in the product market and the markdown in the recycling market. In contrast to the existing works that emphasize that the optimal tax rate is lower than the marginal external da...

  1. MARKETING STRATEGIES OF SMARTPHONES PRODUCERS

    OpenAIRE

    Markova V.; Tzinlin M.; Ge C.

    2017-01-01

    Smartphones global market is one of the most dynamically developing markets that can be characterized by high level of competition. The growth of smartphones homogeneity, which is a reduction in difference between technical and functional parameters of smartphones produced by various manufacturers, can be considered the market’s specific feature. The unique situation of high-tech product homogeneity in a fast-growing market is scantily described in specialized literature. The article shows ch...

  2. Method of producing ethyl alcohol

    Energy Technology Data Exchange (ETDEWEB)

    Philliskirk, G; Yates, H J

    1978-09-13

    Ethanol was produced from whey by removing protein from the whey by ultrafiltration, concentrating the deproteinized whey by reverse osmosis to a lactose content of at least 8 g/100 mL, fermenting with Candida pseudotropicalis NCYC 744, and distilling. E.g., milk whey was deproteinized to give a permeate containing 8.3 g lactose/100 mL. After fermentation, the final lactose content was 0.1 g/100 mL and the ethanol concentration was 3.55 g/100 mL, representing a 42% conversion of lactose to ethanol.

  3. Producing biofuels using polyketide synthases

    Science.gov (United States)

    Katz, Leonard; Fortman, Jeffrey L; Keasling, Jay D

    2013-04-16

    The present invention provides for a non-naturally occurring polyketide synthase (PKS) capable of synthesizing a carboxylic acid or a lactone, and a composition such that a carboxylic acid or lactone is included. The carboxylic acid or lactone, or derivative thereof, is useful as a biofuel. The present invention also provides for a recombinant nucleic acid or vector that encodes such a PKS, and host cells which also have such a recombinant nucleic acid or vector. The present invention also provides for a method of producing such carboxylic acids or lactones using such a PKS.

  4. Uranium producers foresee new boom

    International Nuclear Information System (INIS)

    McIntyre, H.

    1979-01-01

    The status of uranium production in Canada is reviewed. Uranium resources in Saskatchewan and Ontario are described and the role of the Cluff Lake inquiry in securing a government decision in favour of further uranium development is mentioned. There have been other uranium strikes near Kelowna, British Columbia and in the Northwest Territories. Increasing uranium demand and favourable prices are making the development of northern resources economically attractive. In fact, all uranium currently produced has been committed to domestic and export contracts so that there is considerable room for expanding the production of uranium in Canada. (T.I.)

  5. Soybean biomass produced in Argentina

    DEFF Research Database (Denmark)

    Semino, Stella Maris; Paul, Helena; Tomei, Julia

    2009-01-01

    Soybean biomass for biodiesel, produced in Argentina amongst other places, is considered by some to reduce greenhouse gas emissions and mitigate climate change when compared with fossil fuel. To ensure that the production of biofuels is ‘sustainable', EU institutions and national governments...... are currently designing certification schemes for the sustainable production of biomass. This paper questions the validity of proposed environmental standards, using the production of Argentine soybean as a case study. The production of soybean production is associated with profound environmental impacts...

  6. Producing deuterium-enriched products

    International Nuclear Information System (INIS)

    1980-01-01

    A method of producing an enriched deuterium product from a gaseous feed stream of mixed hydrogen and deuterium, comprises: (a) combining the feed stream with gaseous bromine to form a mixture of the feed stream and bromine and exposing the mixture to an electrical discharge effective to form deuterium bromide and hydrogen bromide with a ratio of D/H greater than the ratio of D/H in the feed stream; and (b) separating at least a portion of the hydrogen bromide and deuterium bromide from the mixture. (author)

  7. Fatty acid-producing hosts

    Science.gov (United States)

    Pfleger, Brian F; Lennen, Rebecca M

    2013-12-31

    Described are hosts for overproducing a fatty acid product such as a fatty acid. The hosts include an exogenous nucleic acid encoding a thioesterase and, optionally, an exogenous nucleic acid encoding an acetyl-CoA carboxylase, wherein an acyl-CoA synthetase in the hosts are functionally delected. The hosts prefereably include the nucleic acid encoding the thioesterase at an intermediate copy number. The hosts are preferably recominantly stable and growth-competent at 37.degree. C. Methods of producing a fatty acid product comprising culturing such hosts at 37.degree. C. are also described.

  8. Methods of producing luminescent images

    International Nuclear Information System (INIS)

    Broadhead, P.; Newman, G.A.

    1977-01-01

    A method is described for producing a luminescent image in a layer of a binding material in which is dispersed a thermoluminescent material. The layer is heated uniformly to a temperature of 80 to 300 0 C and is exposed to luminescence inducing radiation whilst so heated. The preferred exposing radiation is X-rays and preferably the thermoluminescent material is insensitive to electromagnetic radiation of wavelength longer than 300 mm. Information concerning preparation of the luminescent material is given in BP 1,347,672; this material has the advantage that at elevated temperatures it shows increased sensitivity compared with room temperature. At temperatures in the range 80 to 150 0 C the thermoluminescent material exhibits 'afterglow', allowing the image to persist for several seconds after the X-radiation has ceased, thus allowing the image to be retained for visual inspection in this temperature range. At higher temperatures, however, there is negligible 'afterglow'. The thermoluminescent layers so produced are particularly useful as fluoroscopic screens. The preferred method of heating the thermoluminescent material is described in BP 1,354,149. An example is given of the application of the method. (U.K.)

  9. Concrete produced with recycled aggregates

    Directory of Open Access Journals (Sweden)

    J. J. L. Tenório

    Full Text Available This paper presents the analysis of the mechanical and durable properties of recycled aggregate concrete (RAC for using in concrete. The porosity of recycled coarse aggregates is known to influence the fresh and hardened concrete properties and these properties are related to the specific mass of the recycled coarse aggregates, which directly influences the mechanical properties of the concrete. The recycled aggregates were obtained from construction and demolition wastes (CDW, which were divided into recycled sand (fine and coarse aggregates. Besides this, a recycled coarse aggregate of a specific mass with a greater density was obtained by mixing the recycled aggregates of the CDW with the recycled aggregates of concrete wastes (CW. The concrete was produced in laboratory by combining three water-cement ratios, the ratios were used in agreement with NBR 6118 for structural concretes, with each recycled coarse aggregates and recycled sand or river sand, and the reference concrete was produced with natural aggregates. It was observed that recycled aggregates can be used in concrete with properties for structural concrete. In general, the use of recycled coarse aggregate in combination with recycled sand did not provide good results; but when the less porous was used, or the recycled coarse aggregate of a specific mass with a greater density, the properties of the concrete showed better results. Some RAC reached bigger strengths than the reference concrete.

  10. How Mobility Systems Produce Inequality

    DEFF Research Database (Denmark)

    Richardson, Tim; Jensen, Ole B.

    2008-01-01

    This paper explores a crucial aspect of sustainable mobility: the production of social inequality in mobility systems. The approach taken is to focus on how, as new transit infrastructures create alternative ways of traveling in and accessing the city, they create changed conditions for the forma......This paper explores a crucial aspect of sustainable mobility: the production of social inequality in mobility systems. The approach taken is to focus on how, as new transit infrastructures create alternative ways of traveling in and accessing the city, they create changed conditions...... for the formation of subject identities. New types of travellers are realised in the newly engineered spaces of mobility. The paper argues that this focus on these emergent mobile subject types can be useful in investigating the social inequalities that can result from the introduction of new infrastructures...... are constructed and how social inequality is materially produced....

  11. Producing The New Regressive Left

    DEFF Research Database (Denmark)

    Crone, Christine

    members, this thesis investigates a growing political trend and ideological discourse in the Arab world that I have called The New Regressive Left. On the premise that a media outlet can function as a forum for ideology production, the thesis argues that an analysis of this material can help to trace...... the contexture of The New Regressive Left. If the first part of the thesis lays out the theoretical approach and draws the contextual framework, through an exploration of the surrounding Arab media-and ideoscapes, the second part is an analytical investigation of the discourse that permeates the programmes aired...... becomes clear from the analytical chapters is the emergence of the new cross-ideological alliance of The New Regressive Left. This emerging coalition between Shia Muslims, religious minorities, parts of the Arab Left, secular cultural producers, and the remnants of the political,strategic resistance...

  12. Conducting nanofibres produced by electrospinning

    Science.gov (United States)

    Sen, S.; Davis, F. J.; Mitchell, G. R.; Robinson, E.

    2009-08-01

    Electrospun fibres based on polypyrrole have been prepared. The incorporation of preformed polypyrrole into fibres electrospun from a carrier polymer can only be achieved when materials are prepared with particulates smaller than the cross-section of the fibre; even so there are some problems, with the substantial loss of material from the electrode tip. As an alternative approach, soluble polypyrroles can be prepared but these are not of sufficient viscosity to prepare electrospun fibres, once again a carrier polymer must be employed. More effective loadings are gained by the process of coating the outer surface of a pre-spun fibre; in this way electrospun fibres coated with polypyrrole can be prepared. This approach has been adapted to produce silver coated polymer fibres by the use of copolymers of styrene and 3-vinyl benzaldehyde.

  13. Conducting nanofibres produced by electrospinning

    International Nuclear Information System (INIS)

    Sen, S; Mitchell, G R; Robinson, E; Davis, F J

    2009-01-01

    Electrospun fibres based on polypyrrole have been prepared. The incorporation of preformed polypyrrole into fibres electrospun from a carrier polymer can only be achieved when materials are prepared with particulates smaller than the cross-section of the fibre; even so there are some problems, with the substantial loss of material from the electrode tip. As an alternative approach, soluble polypyrroles can be prepared but these are not of sufficient viscosity to prepare electrospun fibres, once again a carrier polymer must be employed. More effective loadings are gained by the process of coating the outer surface of a pre-spun fibre; in this way electrospun fibres coated with polypyrrole can be prepared. This approach has been adapted to produce silver coated polymer fibres by the use of copolymers of styrene and 3-vinyl benzaldehyde.

  14. Producer flexibility answers market forces

    International Nuclear Information System (INIS)

    Von Flatern, R.

    1996-01-01

    The petroleum industry was revolutionized in the 1980s when oil became a commodity and rising prices no longer ensured profits. Alliancing, partnering, integration and operator cooperation became economic responses to the 1990s market reality. The industry has long been a bastion of free-marketeering; competition among producers and service providers continues to control prices. But new, more efficient ways of doing business control costs in an industry buffeted by stagnant prices, a prolonged period of downsizing and increasingly difficult and remote operating environments. How long the new business atmosphere will last depends on industry needs and how well things work out. But based on the successes of the immediate past and the foreseeable future, the new cross-company business practices seem destined only to multiply

  15. Process for producing a polymer

    Energy Technology Data Exchange (ETDEWEB)

    Koshimura, M; Haruta, K; Matsuzaka, J; Terakado, H

    1969-02-13

    A novel polymer is produced by a novel polymerization or copolymerization process in the presence of a free radical-forming catalyst or radical-forming irradiation energy to provide a monomer of the general formula CH/sub 2/=C(R/sub 1/)(COO)-(R/sub 2/OOCR/sub 3/COO)sub(n)-R/sub 2/OH wherein R/sub 1/ is hydrogen, halogen or alkyl radical containing one or two atoms; R/sub 2/ is an epoxy compound residue; R/sub 3/ is a polybasic anhydride residue; and n is an integer. This polymer: (1) enables the cross-linking reaction, (2) improves the adhesiveness of adhesives, pigments, films and coatings; (3) is adjustable for mutual solubility and affinity when blending with other solvents and resins; (4) is resistant to yellowing and mechanically stronger than the benzene nucleus of styrene; (5) improves the textile dyeing affinity, adhesiveness and dispersion of pigments, and the dimensional stability of films and sheets; (6) is suitable as a molding material of synthetic resins, adhesives and coatings because of its three dimensional cross-linking construction; (7) can control the hardness, flexibility and rigidity of the molding materials; and (8) can lower the cost of production. In an example, 10 g of the monomer of the above mentioned formula wherein n=1, R/sub 1/=CH/sub 3/, R/sub 2/=-(CH/sub 2/)/sub 2/ and R/sub 3/ is ortho-substituted benzene, and 0.1 g of benzol peroxide, are added to ampoule, sealed and polymerized at 120/sup 0/C for 2 hours. Next the contents are precipitated in a large amount of benzene to produce a polymer having a molecular weight of 9,500. The products have good dimensional stability as molding materials.

  16. Manual for reactor produced radioisotopes

    International Nuclear Information System (INIS)

    2003-01-01

    numerous new developments that have taken place since then. Hence in this manual it was decided to focus only on reactor produced radioisotopes. This manual contains procedures for 48 important reactor-produced isotopes. These were contributed by major radioisotope producers from different parts of the world and are based on their practical experience. In case of widely used radioisotopes such as 131 I, 32 P and 99 Mo, information from more than one centre is included so that the users can compare the procedures. As in the earlier two versions, a general introductory write-up is included covering basic information on related aspects such as target irradiation, handling facilities, radiation protection and transportation, but in less detail. Relevant IAEA publications on such matters, particularly related to radiation protection and transportation, should be referred to for guidelines. Similarly, the nuclear data contained in the manual are only indicative and the relevant databases should be referred to for more authentic values. It is hoped that the manual will be a useful source of information for those working in radioisotope production laboratories as well as those intending to initiate such activities

  17. MARKETING STRATEGIES OF SMARTPHONES PRODUCERS

    Directory of Open Access Journals (Sweden)

    Markova V.

    2017-12-01

    Full Text Available Smartphones global market is one of the most dynamically developing markets that can be characterized by high level of competition. The growth of smartphones homogeneity, which is a reduction in difference between technical and functional parameters of smartphones produced by various manufacturers, can be considered the market’s specific feature. The unique situation of high-tech product homogeneity in a fast-growing market is scantily described in specialized literature. The article shows changeability of smartphones global market leaders and explains that the key success factor in such a mature market is marketing. Based on secondary information, marketing strategies of long standing market leader in sales Samsung and overtaking Apple companies are determined as well as strategies of contenders for leadership - Chinese companies Huawei and Lenovo. It is shown on Lenovo case that inexplicit positioning leads to a loss of the growing market share due to offensive marketing strategies of other Chinese companies. The research results broaden the knowledge of methodical potential of marketing strategies in companies’ activities in competitive markets of homogeneous high-tech products.

  18. Producing tantalum or columbium powder

    International Nuclear Information System (INIS)

    Rerat, C.F.

    1979-01-01

    A process is described for the production of tantalum or columbium powder with a high yield within a desired range of particle sizes. A molten salt bath of a double salt comprising either an alkali metal tantalum fluoride or an alkali metal columbium fluoride and a relatively large amount of alkali metal halide diluent salt to act as a heat sink is initially maintained at a temperature a little above the liquidus temperature of the salt mixture. A liquid alkali metal at a comparatively low temperature is added to the continuously stirred bath at a high mass flow rate, and reduces the double salt, producing tantalum or columbium. The reaction is exothermic and causes the temperature to rise rapidly to a desired final reaction temperature within the range 760 to 1000 0 . The liquid alkali metal is thereafter fed at a high mass flow rate to complete the reaction quickly at the final reaction temperature. Forced cooling at a heat extraction rate not less than 42 kilojoules/min./kg. of double salt is used during at least a portion of the reaction cycle at a rate sufficient to maintain the final reaction temperature within a desired range. (author)

  19. Sideways Force Produced During Disruptions

    Science.gov (United States)

    Strauss, H. R.; Paccagnella, R.; Breslau, J.; Jardin, S.; Sugiyama, L.

    2012-10-01

    We extend previous studies [1] of vertical displacement events (VDE) which can produce disruptions. The emphasis is on the non axisymmetric ``sideways'' wall force Fx. Simulations are performed using the M3D [2] code. A VDE expels magnetic flux through the resistive wall until the last closed flux surface has q VDE is presented. The wall force depends strongly on γτw, where γ is the mode growth rate and τw is the wall resistive penetration time. The force Fx is largest when γτw is a constant of order unity, which depends on the initial conditions. For large values of γτw, the wall force asymptotes to a relatively smaller value, well below the critical value ITER is designed to withstand. The principle of disruption mitigation by massive gas injection is to cause a disruption with large γτw. [4pt] [1] H. R. Strauss, R. Paccagnella, and J. Breslau,Phys. Plasmas 17, 082505 (2010) [2] W. Park, E.V. Belova, G.Y. Fu, X. Tang, H.R. Strauss, L.E. Sugiyama, Phys. Plasmas 6, 1796 (1999).

  20. Yeast: A new oil producer?

    Directory of Open Access Journals (Sweden)

    Beopoulos Athanasios

    2012-01-01

    Full Text Available The increasing demand of plant oils or animal fat for biodiesel and specific lipid derivatives for the oleochemical field (such as lubricants, adhesives or plastics have created price imbalance in both the alimentary and energy field. Moreover, the lack of non-edible oil feedstock has given rise to concerns on land-use practices and on oil production strategies. Recently, much attention has been paid to the exploitation of microbial oils. Most of them present lipid profiles similar in type and composition to plants and could therefore have many advantages as are no competitive with food, have short process cycles and their cultivation is independent of climate factors. Among microorganisms, yeasts seem to be very promising as they can be easily genetically enhanced, are suitable for large-scale fermentation and are devoid of endotoxins. This review will focus on the recent understanding of yeasts lipid metabolism, the succeeding genetic engineering of the lipid pathways and the recent developments on fermentation techniques that pointed out yeasts as promising alternative producers for oil or plastic.

  1. Collision-produced atomic states

    International Nuclear Information System (INIS)

    Andersen, N.; Copenhagen Univ.

    1988-01-01

    The last 10-15 years have witnessed the development of a new, powerful class of experimental techniques for atomic collision studies, allowing partial or complete determination of the state of the atoms after a collision event, i.e. the full set of quantum-mechanical scattering amplitudes or - more generally - the density matrix describing the system. Evidently, such studies, involving determination of alignment and orientation parameters, provide much more severe tests of state-of-the-art scattering theories than do total or differential cross section measurements which depend on diagonal elements of the density matrix. The off-diagonal elements give us detailed information about the shape and dynamics of the atomic states. Therefore, close studies of collision-produced atomic states are currently leading to deeper insights into the fundamental physical mechanisms governing the dynamics of atomic collision events. The first part of the lectures deals with the language used to describe atomic states, while the second part presents a selection of recent results for model systems which display fundamental aspects of the collision physics in particularly instructive ways. I shall here restrict myself to atom-atom collisions. The discussion will be focused on states decaying by photon emission though most of the ideas can be easily modified to include electron emission as well. (orig./AH)

  2. Engineering microbes to produce biofuels.

    Science.gov (United States)

    Wackett, Lawrence P

    2011-06-01

    The current biofuels landscape is chaotic. It is controlled by the rules imposed by economic forces and driven by the necessity of finding new sources of energy, particularly motor fuels. The need is bringing forth great creativity in uncovering new candidate fuel molecules that can be made via metabolic engineering. These next generation fuels include long-chain alcohols, terpenoid hydrocarbons, and diesel-length alkanes. Renewable fuels contain carbon derived from carbon dioxide. The carbon dioxide is derived directly by a photosynthetic fuel-producing organism(s) or via intermediary biomass polymers that were previously derived from carbon dioxide. To use the latter economically, biomass depolymerization processes must improve and this is a very active area of research. There are competitive approaches with some groups using enzyme based methods and others using chemical catalysts. With the former, feedstock and end-product toxicity loom as major problems. Advances chiefly rest on the ability to manipulate biological systems. Computational and modular construction approaches are key. For example, novel metabolic networks have been constructed to make long-chain alcohols and hydrocarbons that have superior fuel properties over ethanol. A particularly exciting approach is to implement a direct utilization of solar energy to make a usable fuel. A number of approaches use the components of current biological systems, but re-engineer them for more direct, efficient production of fuels. Copyright © 2010 Elsevier Ltd. All rights reserved.

  3. Reactor-produced therapeutic radioisotopes

    International Nuclear Information System (INIS)

    Knapp, F.F. Jr.

    2002-01-01

    The significant worldwide increase in therapeutic radioisotope applications in nuclear medicine, oncology and interventional cardiology requires the dependable production of sufficient levels of radioisotopes for these applications (Reba, 2000; J. Nucl. Med., 1998; Nuclear News, 1999; Adelstein and Manning, 1994). The issues associated with both accelerator- and reactor-production of therapeutic radioisotopes is important. Clinical applications of therapeutic radioisotopes include the use of both sealed sources and unsealed radiopharmaceutical sources. Targeted radiopharmaceutical agents include those for cancer therapy and palliation of bone pain from metastatic disease, ablation of bone marrow prior to stem cell transplantation, treatment modalities for mono and oligo- and polyarthritis, for cancer therapy (including brachytherapy) and for the inhibition of the hyperplastic response following coronary angioplasty and other interventional procedures (For example, see Volkert and Hoffman, 1999). Sealed sources involve the use of radiolabeled devices for cancer therapy (brachytherapy) and also for the inhibition of the hyperplasia which is often encountered after angioplasty, especially with the exponential increase in the use of coronary stents and stents for the peripheral vasculature and other anatomical applications. Since neutron-rich radioisotopes often decay by beta decay or decay to beta-emitting daughter radioisotopes which serve as the basis for radionuclide generator systems, reactors are expected to play an increasingly important role for the production of a large variety of therapeutic radioisotopes required for these and other developing therapeutic applications. Because of the importance of the availability of reactor-produced radioisotopes for these applications, an understanding of the contribution of neutron spectra for radioisotope production and determination of those cross sections which have not yet been established is important. This

  4. 7 CFR 1206.16 - Producer.

    Science.gov (United States)

    2010-01-01

    ... producing, or causing to be produced, mangos beyond the person's own family use and having value at first... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE MANGO PROMOTION, RESEARCH, AND INFORMATION Mango Promotion, Research, and Information Order Definitions § 1206.16 Producer. Producer means...

  5. The dating of rock surfaces using in situ produced 10Be, 26Al and 36Cl, with examples from Antarctica and the Swiss Alps

    International Nuclear Information System (INIS)

    Ivy Ochs, S.D.

    1996-01-01

    A primary concern today in ice age research is to elucidate the worldwide timing of glacial fluctuations. This information is needed to define the mechanisms by which signals are initiated, and then transferred throughout the various global systems. Because of the importance of integrating the terrestrial records of the former extent of both ice sheets and alpine glaciers, the direct dating of rock surfaces with in situ produced cosmogenic isotopes is an essential tool. These isotopes (e.g. 10 Be, 26 Al and 36 Cl) are produced in the surfaces of rocks due to interactions with cosmic rays. In order to be able to reliably determine exposure ages from rock surfaces with both long and short exposure times, our goal at the onset of this project was to set-up the extraction procedure for Be, Al, Cl from rock samples. 73 separate rock or mineral dissolutions, involving 52 different rock samples, were performed to 1) make sure that meteoric 10 Be was being removed, 2) verify the reproducibility of the procedure, and 3) eventually, address several questions on the timing of glacier fluctuations in two specific geographic areas: Antarctica and the Swiss Alps. Exposure dates we have determined from erratic boulders in the Sirius Group sediments at Mount Fleming proved conclusively that this outcrop of the Sirius Group is more than 5.8 million years old. Minimum ages for Sirius Group deposits at Table Mountain and Mount Feather are 2.9 and 2.3 Ma, respectively. Our results have provided support for the idea that the East Antarctic Ice Sheet, a crucial variable in projections of greenhouse scenarios, is a stable feature of Antarctica. We have investigated three key sites in Switzerland related to the timing of glaciations of the Alps. (author) figs., tabs., refs

  6. Appendix to Health and Safety Laboratory environmental quarterly, March 1, 1976--June 1, 1976. [Tabulated data on content of lead in surface air and /sup 7/Be, /sup 95/Zr, /sup 137/Cs, /sup 144/Ce, and /sup 90/Sr in surface air, milk, drinking water, and foods sampled in USA

    Energy Technology Data Exchange (ETDEWEB)

    Hardy, E.P. Jr.

    1976-07-01

    Tabulated data are presented on: the monthly deposition of /sup 89/Sr and /sup 90/Sr at some 100 world land sites; the content of lead and /sup 7/Be, /sup 95/Zr, /sup 137/Cs, and /sup 144/Ce in samples of surface air from various world sites; and the content of /sup 90/Sr in samples of milk, drinking water, and animal and human diets collected at various locations throughout the USA. (CH)

  7. Mass-producing B mesons

    Energy Technology Data Exchange (ETDEWEB)

    Aleksan, Roy; Ali, Ahmed

    1993-06-15

    Since the discovery of the upsilon resonances in 1977 the physics of the fifth quark - beauty - has played a vital role in establishing and consolidating today's Standard Model of particle physics. In recent years, a wealth of data on B particle (containing the beauty quark) has emerged from the detectors ARGUS (at the DORIS ring, DESY, Hamburg) and CLEO (at the Cornell CESR ring) as well as from CERN's LEP electron-positron collider and the proton-antiproton colliders at CERN and Fermilab. But the most challenging goal of this physics is to explore the mystery of CP violation, so far only seen in neutral kaon decays. This subtle mechanism - a disregard for the combined symmetry of particle antiparticle switching and left-right reflection - possibly moulded the evolution of the Universe after the Big Bang, providing a world dominated by matter, rather than one where matter and antimatter play comparable roles. To fully explore CP violation in the laboratory needs a dedicated machine - a particle 'factory' - to mass produce B mesons. Only when this full picture of CP violation has been revealed will physicists finally be able to solve its mysteries. As well as major proposals in the US and Japan, several ideas have been launched in Europe. Over the years, many working groups have accumulated an impressive amount of data and knowledge on the physics as well as on the machine and detectors. The spearheads of experimental B physics are the ARGUS and CLEO collaborations. Highlights include the determination of the parameters of the (Cabibbo-Kobayashi-Maskawa, CKM) quark mixing matrix, testing the consistency of the Standard Model with six quarks and three leptons, and giving the first indirect hint that the as yet unseen sixth ('top') quark is very heavy, together with initial indications of how it should decay. Valuable complementary information has come from proton-antiproton collider data and particularly from the LEP experiments at the Z resonance. Experiments at

  8. Mass-producing B mesons

    International Nuclear Information System (INIS)

    Aleksan, Roy; Ali, Ahmed

    1993-01-01

    Since the discovery of the upsilon resonances in 1977 the physics of the fifth quark - beauty - has played a vital role in establishing and consolidating today's Standard Model of particle physics. In recent years, a wealth of data on B particle (containing the beauty quark) has emerged from the detectors ARGUS (at the DORIS ring, DESY, Hamburg) and CLEO (at the Cornell CESR ring) as well as from CERN's LEP electron-positron collider and the proton-antiproton colliders at CERN and Fermilab. But the most challenging goal of this physics is to explore the mystery of CP violation, so far only seen in neutral kaon decays. This subtle mechanism - a disregard for the combined symmetry of particle antiparticle switching and left-right reflection - possibly moulded the evolution of the Universe after the Big Bang, providing a world dominated by matter, rather than one where matter and antimatter play comparable roles. To fully explore CP violation in the laboratory needs a dedicated machine - a particle 'factory' - to mass produce B mesons. Only when this full picture of CP violation has been revealed will physicists finally be able to solve its mysteries. As well as major proposals in the US and Japan, several ideas have been launched in Europe. Over the years, many working groups have accumulated an impressive amount of data and knowledge on the physics as well as on the machine and detectors. The spearheads of experimental B physics are the ARGUS and CLEO collaborations. Highlights include the determination of the parameters of the (Cabibbo-Kobayashi-Maskawa, CKM) quark mixing matrix, testing the consistency of the Standard Model with six quarks and three leptons, and giving the first indirect hint that the as yet unseen sixth ('top') quark is very heavy, together with initial indications of how it should decay. Valuable complementary information has come from proton-antiproton collider data and particularly from the LEP experiments at the

  9. Numerical dating of a Late Quaternary spit-shoreline complex at the northern end of Silver Lake playa, Mojave Desert, California: A comparison of the applicability of radiocarbon, luminescence, terrestrial cosmogenic nuclide, electron spin resonance, U-series and amino acid racemization methods

    Science.gov (United States)

    Owen, L.A.; Bright, Jordon; Finkel, R.C.; Jaiswal, M.K.; Kaufman, D.S.; Mahan, S.; Radtke, U.; Schneider, J.S.; Sharp, W.; Singhvi, A.K.; Warren, C.N.

    2007-01-01

    A Late Quaternary spit-shoreline complex on the northern shore of Pleistocene Lake Mojave of southeastern California, USA was studied with the goal of comparing accelerator mass spectrometry (AMS) radiocarbon, luminescence, electron spin resonance (ESR), terrestrial cosmogenic radionuclide (TCN) surface exposure, amino acid racemization (AAR) and U-series dating methods. The pattern of ages obtained by the different methods illustrates the complexity of processes acting in the lakeshore environment and highlights the utility of a multi-method approach. TCN surface exposure ages (mostly ???20-30 ka) record the initial erosion of shoreline benches, whereas radiocarbon ages on shells (determined in this and previous studies) within the spit, supported by AAR data, record its construction at fluctuating lake levels from ???16 to 10 ka. Luminescence ages on spit sediment (???6-7 ka) and ESR ages on spit shells (???4 ka) are anomalously young relative to radiocarbon ages of shells within the same deposits. The significance of the surprisingly young luminescence ages is not clear. The younger ESR ages could be a consequence of post-mortem enrichment of U in the shells. High concentrations of detrital thorium in tufa coating spit gravels inhibited the use of single-sample U-series dating. Detailed comparisons such as this provide one of the few means of assessing the accuracy of Quaternary dating techniques. More such comparisons are needed. ?? 2007 Elsevier Ltd and INQUA.

  10. Long-term variation of atmospheric beryllium-7 in Taiwan

    International Nuclear Information System (INIS)

    Yu-Ming Lin; Chi-Chang Liu; Ching-Jiang Chen

    1996-01-01

    Taiwan Radiation Monitoring Center (TRMC) has measured the concentration of atmospheric 7 Be at tile four stations on Taiwan for almost twenty years. Gamma emitting nuclides have been collected by air samplers and measured by gamma spectrometry. Cosmogenic 7 Be and other man-made radionuclides produced by Chinese nuclear weapon testings have been detected. Compared with 7 Be, man-made nuclides vanished quickly because of their short half life. The behaviour of 7 Be in long-term concentration variation is different between northern and southern Taiwan because of local meteorological conditions. Tile results of Fourier analysis show that washout effect of rainfalls and transportation from stratosphere to troposphere are closely related to tile variation of 7Be concentration in near surface air. All the measured data of 7 Be show that tile characteristic of yearly data coincides with tile 11-year solar cycle. (author)

  11. 7 CFR 1212.19 - Producer.

    Science.gov (United States)

    2010-01-01

    ... producing, or causing to be produced, honey beyond personal use and having value at first point of sale. ... person who is engaged in the production and sale of honey in any State and who owns, or shares the...

  12. Genetic engineering of to produce Bacterial Polyhydroxyalkanotes ...

    African Journals Online (AJOL)

    PHAs), in the sense of an environmental precaution appears meaningful and necessary. In order to more economically produce microbial products, this investigation was focused on suitable producers, like the yeast Schizosaccharomyces pombe ...

  13. Characterization of bacteriocin produced by Lactobacillus plantarum ...

    African Journals Online (AJOL)

    Characterization of bacteriocin produced by Lactobacillus plantarum F1 and ... brevis OG1 isolated from Nigerian fermented food products, produced bacteriocins ... interest for food safety and may have future applications as food preservative.

  14. 7 CFR 1131.13 - Producer milk.

    Science.gov (United States)

    2010-01-01

    ... Handling Definitions § 1131.13 Producer milk. Producer milk means the skim milk (or the skim equivalent of components of skim milk) and butterfat in milk of a producer that is: (a) Received by the operator of a pool... percentage in paragraph (d)(2) of this section may be increased or decreased by the market administrator if...

  15. 7 CFR 1033.13 - Producer milk.

    Science.gov (United States)

    2010-01-01

    ... Handling Definitions § 1033.13 Producer milk. Producer milk means the skim milk (or the skim equivalent of components of skim milk), including nonfat components, and butterfat in milk of a producer that is: (a... percentages in paragraph (d)(4) of this section may be increased or decreased by the market administrator if...

  16. 7 CFR 1001.13 - Producer milk.

    Science.gov (United States)

    2010-01-01

    ... Handling Definitions § 1001.13 Producer milk. Producer milk means the skim milk (or the skim equivalent of components of skim milk) and butterfat contained in milk of a producer that is: (a) Received by the operator... be increased or decreased by the Market Administrator if the Market Administrator finds that such...

  17. 7 CFR 1126.13 - Producer milk.

    Science.gov (United States)

    2010-01-01

    ... Handling Definitions § 1126.13 Producer milk. Producer milk means the skim milk (or the skim equivalent of components of skim milk), including nonfat components, and butterfat contained in milk of a producer that is...) of this section may be increased or decreased by the market administrator if there is a finding that...

  18. 7 CFR 1006.13 - Producer milk.

    Science.gov (United States)

    2010-01-01

    ... Handling Definitions § 1006.13 Producer milk. Producer milk means the skim milk (or the skim equivalent of components of skim milk) and butterfat contained in milk of a producer that is: (a) Received by the operator... (d) (1) through (3) of this section may be increased or decreased by the market administrator if the...

  19. 29 CFR 780.213 - Produce business.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 3 2010-07-01 2010-07-01 false Produce business. 780.213 Section 780.213 Labor Regulations... Specific Situations Hatchery Operations § 780.213 Produce business. In some instances, hatcheries also engage in the produce business as such and commingle with the culled eggs and chickens other eggs and...

  20. Cosmic ray produced sodium and its applications

    International Nuclear Information System (INIS)

    Goncalves Barbosa, A.

    1981-07-01

    The following topics were presented: calculations of the theoretical production rate of sodium-22 in the atmosphere in order to estimate its activity in rain water; description of the method of chemical separation of sodium and of counting of various radionuclide samples; results obtained for 22 Na, 137 Cs, 144 Ce, 7 Be and 210 Pb and seasonal variations of these radionuclides in rain and river waters; seasonal variations of natural elements, sodium, potassium and uranium in rain and river waters [fr

  1. Environmental background level of cosmic ray produced 22Na

    International Nuclear Information System (INIS)

    Tokuyama, H.; Oonishi, M.; Matsuura, H.

    1993-01-01

    The annual deposition rate of cosmogenic 22 Na has been studied at Fukui City, Japan, to obtain the current background level. The deposition rate was found to range from 0.16 to 0.22 Bq m -2 y -1 with a mean value of 0.20 Bq m -2 y -1 for the years 1986-1990. The author's results agree fairly well with those observed for the years 1975-1977 in Tokyo. The 22 Na concentration in rain water was also estimated. The mean value for this period was found to be 0.09 mBq litre -1 , which is about one-third of that detected during the latter half of the 1950's. The high levels of environmental 22 Na in the 1950's are attributed to the many nuclear weapon tests conducted at that time. At present, however, the 22 Na from these weapons tests has practically decayed and the concentration in rain water has decreased to the natural background level. (Author)

  2. Late Pleistocene deglaciation chronology in the NW of the Iberian Peninsula using cosmic-ray produced 21Ne in quartz

    International Nuclear Information System (INIS)

    Fernandez Mosquera, D.; Marti, K.; Romani, J.R. Vidal; Weigel, A.

    2000-01-01

    Late Pleistocene glaciations in the NW Iberian Peninsula over Serra de Queixa and Serra de Xures, all with granite substrata, were studied by mass spectrometry using cosmogenic 21 Ne. Rock cores were drilled in glacial polished surfaces and push-moraine boulders, and were analyzed to determine their integral exposure time to cosmic rays. First results, which are consistent with the relative geomorphologic model estimates, allow the identification of at least three different glacial stages, with the latest terminating about 15 ka BP

  3. Inventory transparency for agricultural produce through IOT

    Science.gov (United States)

    Srinivasan, S. P.; Sorna Shanthi, D.; Anand, Aashish V.

    2017-06-01

    Re-structuring the practices of traditional inventory management is becoming more essential to optimize the supply chain transparency and accuracy of agricultural produce. A flexible and transparent inventory management system is becoming the need of any agricultural commodity. It was noticed that the major setback for the farmers who are the suppliers of the farm produce is due to poor supply chain integration. The recent advent technologies and IT explosion can bring up a greater impact in the process of storing, tracking, distributing and monitoring perishable agriculture produce of day to day life. The primary focus of this paper is to integrate IoT into inventory management and other inbound logistics management of agriculture produce. The unique features of agricultural produce like a prediction of supply, demand, the location of warehouses, distribution and tracking of inventory can be integrated through IoT. This paper proposes a conceptual framework for inventory management transparency involved in the supply chain of agriculture produce.

  4. Process for producing ethanol from syngas

    Science.gov (United States)

    Krause, Theodore R; Rathke, Jerome W; Chen, Michael J

    2013-05-14

    The invention provides a method for producing ethanol, the method comprising establishing an atmosphere containing methanol forming catalyst and ethanol forming catalyst; injecting syngas into the atmosphere at a temperature and for a time sufficient to produce methanol; and contacting the produced methanol with additional syngas at a temperature and for a time sufficient to produce ethanol. The invention also provides an integrated system for producing methanol and ethanol from syngas, the system comprising an atmosphere isolated from the ambient environment; a first catalyst to produce methanol from syngas wherein the first catalyst resides in the atmosphere; a second catalyst to product ethanol from methanol and syngas, wherein the second catalyst resides in the atmosphere; a conduit for introducing syngas to the atmosphere; and a device for removing ethanol from the atmosphere. The exothermicity of the method and system obviates the need for input of additional heat from outside the atmosphere.

  5. Bioavailability of isoflavones from soy products in equol producers and non-producers in Japanese women

    Directory of Open Access Journals (Sweden)

    Ayako Miura

    2016-12-01

    Conclusions: The results in this study suggest that bioavailability of isoflavones are different between equol producers and non-producers, because the 24 h urinary excretion of equol in the equol producers were significantly lower than those in the equol non-producers.

  6. Stable, fertile, high polyhydroxyalkanoate producing plants and methods of producing them

    Energy Technology Data Exchange (ETDEWEB)

    Bohmert-Tatarev, Karen; McAvoy, Susan; Peoples, Oliver P.; Snell, Kristi D.

    2015-08-04

    Transgenic plants that produce high levels of polyhydroxybutyrate and methods of producing them are provided. In a preferred embodiment the transgenic plants are produced using plastid transformation technologies and utilize genes which are codon optimized. Stably transformed plants able to produce greater than 10% dwt PHS in tissues are also provided.

  7. Potential biosurfactant producing endophytic and epiphytic fungi ...

    African Journals Online (AJOL)

    Potential biosurfactant producing endophytic and epiphytic fungi, isolated from macrophytes in the Negro River in Manaus, Amazonas, Brazil. ... Solms and Cyperus ligularis L., macrophytes collected from oil-contaminated waters, were studied to assess their potential for producing biosurfactants; the most promising ones ...

  8. Understanding producers' motives for adopting sustainable practices

    NARCIS (Netherlands)

    Trujillo-Barrera, Andres; Pennings, Joost M.E.; Hofenk, Dianne

    2016-01-01

    Understanding the motives and risk attitudes of producers to engage in sustainable practices is important for policy-makers who wish to increase the likelihood of adoption and improve the design of incentives. This article examines the underlying motives of producers to adopt sustainable

  9. Does Bt Corn Really Produce Tougher Residues

    Science.gov (United States)

    Bt corn hybrids produce insecticidal proteins that are derived from a bacterium, Bacillus thuringiensis. There have been concerns that Bt corn hybrids produce residues that are relatively resistant to decomposition. We conducted four experiments that examined the decomposition of corn residues und...

  10. 7 CFR 1124.13 - Producer milk.

    Science.gov (United States)

    2010-01-01

    ... section, Producer milk means the skim milk (or skim milk equivalent of components of skim milk), including... filed a request in writing with the market administrator before the first day of the month the agreement... producer deliveries of each according to a method approved by the market administrator. (4) Diverted milk...

  11. Automatic produce quality monitoring in Reefer containers

    NARCIS (Netherlands)

    Lukasse, L.J.S.; Sanders, M.G.; Kramer, de J.E.

    2003-01-01

    Current day perishable supply chains require intermediate points for manual produce quality inspection. Over the last decade international seatransport of fruit and vegetables in reefer containers has grown tremendously. Reefer containers may completely close the cold chain only if produce quality

  12. 7 CFR 1206.8 - Foreign producer.

    Science.gov (United States)

    2010-01-01

    ... produced, mangos beyond the person's own family use and having value at first point of sale. ... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE MANGO PROMOTION, RESEARCH, AND INFORMATION Mango Promotion, Research, and Information Order Definitions § 1206.8 Foreign producer. Foreign...

  13. Technology development for producing nickel metallic filters

    International Nuclear Information System (INIS)

    Hubler, C.H.

    1990-01-01

    A technology to produce metallic filters by Instituto de Engenharia Nuclear (IEN-Brazilian CNEN) providing the Instituto de Pesquisas Energeticas e Nucleares (IPEN-Brazilian CNEN) in obtaining nickel alloy filters used for filtration process of uranium hexafluoride, was developed. The experiences carried out for producing nickel conical trunk filters from powder metallurgy are related. (M.C.K.)

  14. Music Teacher as Writer and Producer

    Science.gov (United States)

    Randles, Clint

    2012-01-01

    In this article I attempt to redefine the role of a music teacher as being more than a director, the more traditional term ascribed to this position. I do this by using descriptions of the role of "writer" and "producer" of student lives borrowed from music education philosophy, screenwriting, and professional music producers. This vision is…

  15. Isolation and molecular characterization of phytase producing ...

    African Journals Online (AJOL)

    Isolation and molecular characterization of phytase producing bacteria from Malaysia hot springs. ... The strains were further analyzed in broth culture using sodium phytate as substrate. Among them, strain L3 was selected as the best producer (0.16 U/ml after 72 h of culture). This phytase showed optimal activity at 37 °C ...

  16. Extended Producer Responsibility in the Aviation Sector

    OpenAIRE

    Brito, Marisa; Laan, Erwin; Irion, B.D.

    2007-01-01

    textabstractIn this paper we investigate recent initiatives with respect to extended producer responsibility in the aviation sector. We compare those with the existing practices in the automobile sector and the emerging regulations in the shipping sector. We describe the challenges and the lessons to be learned from the evolution and state of extended producer responsibility in these two industries.

  17. Exopolysaccharides produced by lactic acid bacteria

    NARCIS (Netherlands)

    Caggianiello, Graziano; Kleerebezem, Michiel; Spano, Giuseppe

    2016-01-01

    A wide range of lactic acid bacteria (LAB) is able to produce capsular or extracellular polysaccharides, with various chemical compositions and properties. Polysaccharides produced by LAB alter the rheological properties of the matrix in which they are dispersed, leading to typically viscous and

  18. Producer services, economic geography, and services tradability

    NARCIS (Netherlands)

    de Vaal, A; van den Berg, M

    We investigate how the incorporation of producer services linkages affects the outcome of an economic geography model. We specify the production of manufactures such that a variety of producer services is needed to transform tradable unfinished goods into final consumption goods. We find that

  19. Applicability of a portable CdTe and NaI (Tl) spectrometer for activity measure; Aplicabilidade de um espectrometro portatil de CdTe e NaI (Tl) para a medida da atividade de Cesio-137 ({sup 137}Cs) e Berilio-7 ({sup 7}Be)

    Energy Technology Data Exchange (ETDEWEB)

    Fernandes, Jaquiel Salvi

    2005-02-15

    In this work it was studied the application of an in situ gamma spectrometer (ROVER) of Amptek Inc., composed by a Cadmium Telluride detector (CdTe) of 3 mm x 3 mm x 1 mm and a 30 mm x 30 mm Sodium Iodide detector doped with Thallium [NaI (Tl)). The radioactive sources used were type pastille, sealed in aluminum and polyethylene, of {sup 241}Am, {sup 133}Ba, {sup 152}Eu, 3 sources of {sup 137}Cs and soil samples contaminated with {sup 137}Cs. It was performed a factorial planning 2{sup 3} to optimize the in situ spectrometry system. This way it was determined that the best temperature for CdTe crystal operation is -22, deg C, with Shaping Time of 3 {mu}S and Rise Time Discrimination (RTD) with value 3. With the help of the certified radioactive sources, we determined the efficiency curve of the two detectors. The CdTe detector was positioned at the standard distance of 1 meter of the sources and also at 4.15 cm. The NaI (Tl) detector was also positioned at the standard distance of 1 meter of the sources and at 2.8 cm. Measures were performed to determine the Minimum Detectable Activity (MDA) for both detectors. For the pastille type sources, the {sup 137}Cs MDA for the CdTe detector at 4.15 cm, analyzing the energy line of 32 keV, was 6 kBq and at 1 meter of the {sup 137}Cs source, analyzing the line of 661.65 keV, the MDA was 67 kBq. For soil samples, CdTe detector at 4.15 cm presented a MDA of 693 kBq.kg-l for the line of 32 keV, and for the soil sample {sup 7}Be content the MDA found was 2867 Bq.kg{sup -1} at 4.15 cm. For the NaI (Tl) detector, analyzing the line of 661.65 keV, the {sup 137}Cs MDA for pastille type source at 1 meter of distance was 7 kBq, and for soil sample at 2.8 cm the measured {sup 137}Cs MDA was 71 Bq.kg{sup -1}. For the soil sample {sup 7}Be content, at 2.8 cm of the Nal (Tl) detector, the obtained MDA was 91 Bq.kg{sup -1}. Due to the minimum detectable activities found for the two detectors, we concluded that the employed in situ gamma

  20. Bacteriocin producers from traditional food products

    Directory of Open Access Journals (Sweden)

    Thonart P.

    2007-01-01

    Full Text Available A total of 220 strains of LAB isolated from 32 samples of traditional fermented food from Senegal were screened for bacteriocin production. Two bacteriocin producers, Lactococcus lactis subsp. lactis and Enterococcus faecium, were identified from 12 bacteriocin-producing isolates on the basis of phenotypic analyses and 16S rDNA sequence. Both bacteriocins produced by new isolates show antimicrobial activity against Listeria monocytogenes and Bacillus coagulans whereas only that produced by Lactococcus lactis has an activity against Bacillus cereus. Bacteriocin-producing Lactococcus lactis strains were found in a variety of traditional foods indicating a high potential of growth of this strain in variable ecological complex environment. Partial 16S rDNA of the two bacteriocin producers obtained in this study has been registered to Genbank databases under the accession number AY971748 for Lactococcus lactis subsp. lactis (named CWBI-B1410 and AY971749 for Enterococcus faecium (named CWBI-B1411. The new bacteriocin-producing Lactococcus lactis subsp. lactis strain has been selected for identification and application of the bacteriocin to food preservation.

  1. US producers in a competitive market

    International Nuclear Information System (INIS)

    Beck, M.

    1987-01-01

    The current (1986) situation in the world-wide uranium market is explained and the competitiveness of United States producers is considered in this context. Historical export contracts by US producers are examined to evaluate how sales quantities by region have changed. The influence of inflation and exchange rates on production costs are considered. The threat of US protectionism is discussed. Despite the contraction of the US uranium industry in recent years a number of US producers have remained competitive. Factors which could increase US competitiveness are listed. (U.K.)

  2. Method for producing uranium atomic beam source

    International Nuclear Information System (INIS)

    Krikorian, O.H.

    1976-01-01

    A method is described for producing a beam of neutral uranium atoms by vaporizing uranium from a compound UM/sub x/ heated to produce U vapor from an M boat or from some other suitable refractory container such as a tungsten boat, where M is a metal whose vapor pressure is negligible compared with that of uranium at the vaporization temperature. The compound, for example, may be the uranium-rhenium compound, URe 2 . An evaporation rate in excess of about 10 times that of conventional uranium beam sources is produced

  3. Methods and systems for producing syngas

    Science.gov (United States)

    Hawkes, Grant L; O& #x27; Brien, James E; Stoots, Carl M; Herring, J. Stephen; McKellar, Michael G; Wood, Richard A; Carrington, Robert A; Boardman, Richard D

    2013-02-05

    Methods and systems are provided for producing syngas utilizing heat from thermochemical conversion of a carbonaceous fuel to support decomposition of at least one of water and carbon dioxide using one or more solid-oxide electrolysis cells. Simultaneous decomposition of carbon dioxide and water or steam by one or more solid-oxide electrolysis cells may be employed to produce hydrogen and carbon monoxide. A portion of oxygen produced from at least one of water and carbon dioxide using one or more solid-oxide electrolysis cells is fed at a controlled flow rate in a gasifier or combustor to oxidize the carbonaceous fuel to control the carbon dioxide to carbon monoxide ratio produced.

  4. Natural rubber producing plants: An overview | Venkatachalam ...

    African Journals Online (AJOL)

    ... Hevea and also other natural rubber producing species for alternative source of latex production in the near future. Keywords: Alternative rubber sources, biotechnology, breeding, Hevea brasiliensis, Parthenium argentatum, Taraxacum koksaghyz, Ficus bengalensis, Lactuca serriola. African Journal of Biotechnology Vol.

  5. Methods of producing compounds from plant materials

    Science.gov (United States)

    Werpy, Todd A [West Richland, WA; Schmidt, Andrew J [Richland, WA; Frye, Jr., John G.; Zacher, Alan H. , Franz; James A. , Alnajjar; Mikhail S. , Neuenschwander; Gary G. , Alderson; Eric V. , Orth; Rick J. , Abbas; Charles A. , Beery; Kyle E. , Rammelsberg; Anne M. , Kim; Catherine, J [Decatur, IL

    2010-01-26

    The invention includes methods of processing plant material by adding water to form a mixture, heating the mixture, and separating a liquid component from a solid-comprising component. At least one of the liquid component and the solid-comprising component undergoes additional processing. Processing of the solid-comprising component produces oils, and processing of the liquid component produces one or more of glycerol, ethylene glycol, lactic acid and propylene glycol. The invention includes a process of forming glycerol, ethylene glycol, lactic acid and propylene glycol from plant matter by adding water, heating and filtering the plant matter. The filtrate containing starch, starch fragments, hemicellulose and fragments of hemicellulose is treated to form linear poly-alcohols which are then cleaved to produce one or more of glycerol, ethylene glycol, lactic acid and propylene glycol. The invention also includes a method of producing free and/or complexed sterols and stanols from plant material.

  6. Methods of producing compounds from plant material

    Energy Technology Data Exchange (ETDEWEB)

    Werpy, Todd A.; Schmidt, Andrew J.; Frye, Jr., John G.; Zacher, Alan H.; Franz, James A.; Alnajjar, Mikhail S.; Neuenschwander, Gary G.; Alderson, Eric V.; Orth, Rick J.; Abbas, Charles A.; Beery, Kyle E.; Rammelsberg, Anne M.; Kim, Catherine J.

    2006-01-03

    The invention includes methods of processing plant material by adding water to form a mixture, heating the mixture, and separating a liquid component from a solid-comprising component. At least one of the liquid component and the solid-comprising component undergoes additional processing. Processing of the solid-comprising component produces oils, and processing of the liquid component produces one or more of glycerol, ethylene glycol, lactic acid and propylene glycol. The invention includes a process of forming glycerol, ethylene glycol, lactic acid and propylene glycol from plant matter by adding water, heating and filtering the plant matter. The filtrate containing starch, starch fragments, hemicellulose and fragments of hemicellulose is treated to form linear poly-alcohols which are then cleaved to produce one or more of glycerol, ethylene glycol, lactic acid and propylene glycol. The invention also includes a method of producing free and/or complexed sterols and stanols from plant material.

  7. (ESBL) producing Escherichia coli and Klebsiella pneumoniae

    African Journals Online (AJOL)

    use

    2011-11-21

    Nov 21, 2011 ... the most common serious bacterial infections in infants ... UTI is a common cause of morbidity .... of ESBL and non-ESBL producing Escherichia coli and Klebsiella pneumonia. ... in hospital and community acquired infections.

  8. Must producers earn a resource rent?

    International Nuclear Information System (INIS)

    Austvik, Ole Gunnar

    2003-01-01

    In petroleum producing countries it has been a prevailing opinion that a resource rent should be earned by petroleum producers due to the commodities' non-renewable nature. An important element in this logic is that the supply of oil and natural gas is limited to relatively few places in the world. As the resources are exploited, the remaining reserves are reduced. What is extracted today cannot be extracted tomorrow. Rationing of the scarce resource takes place through pricing mechanisms. Due to the scarcity the consumers must pay a higher price than the marginal production costs, so that the amounts supplied and demanded become equal. Most producers of oil and gas and not just the ones that produce the cheapest, have therefore until now earned an economic rent

  9. How to: Produce a Good Poster.

    Science.gov (United States)

    Simmonds, D

    1984-01-01

    'Poster sessions' have become a widespread feature of medical meetings. Here, an experienced medical artist gives his guidelines for producing a poster that provides clear information in an attractive and easy-to-assemble format.

  10. Sideways wall force produced during tokamak disruptions

    Science.gov (United States)

    Strauss, H.; Paccagnella, R.; Breslau, J.; Sugiyama, L.; Jardin, S.

    2013-07-01

    A critical issue for ITER is to evaluate the forces produced on the surrounding conducting structures during plasma disruptions. We calculate the non-axisymmetric ‘sideways’ wall force Fx, produced in disruptions. Simulations were carried out of disruptions produced by destabilization of n = 1 modes by a vertical displacement event (VDE). The force depends strongly on γτwall, where γ is the mode growth rate and τwall is the wall penetration time, and is largest for γτwall = constant, which depends on initial conditions. Simulations of disruptions caused by a model of massive gas injection were also performed. It was found that the wall force increases approximately offset linearly with the displacement from the magnetic axis produced by a VDE. These results are also obtained with an analytical model. Disruptions are accompanied by toroidal variation of the plasma current Iφ. This is caused by toroidal variation of the halo current, as verified computationally and analytically.

  11. Do bacteria, not fish, produce 'fish kairomone'?

    NARCIS (Netherlands)

    Ringelberg, J.; Van Gool, E.

    1998-01-01

    Fish-associated chemicals enhance phototactic downward swimming in Daphnia. If perch were treated with the antibiotic ampicillin, this enhancement was significantly decreased. Therefore, not fish, but bacteria associated with fish, seem to produce this kairomone. [KEYWORDS: Diel vertical migration;

  12. 7 CFR 1430.510 - New producers.

    Science.gov (United States)

    2010-01-01

    ... AGRICULTURE LOANS, PURCHASES, AND OTHER OPERATIONS DAIRY PRODUCTS Dairy Market Loss Assistance Program § 1430... in 1999 or 2000 and not affiliated with other eligible producers may receive payments from sums made...

  13. Diagnostics of laser-produced plasmas

    Directory of Open Access Journals (Sweden)

    Batani Dimitri

    2016-12-01

    Full Text Available We present the general challenges of plasma diagnostics for laser-produced plasmas and give a few more detailed examples: spherically bent crystals for X-ray imaging, velocity interferometers (VISAR for shock studies, and proton radiography.

  14. An anaerobic mitochondrion that produces hydrogen

    NARCIS (Netherlands)

    Boxma, Brigitte; Graaf, Rob M. de; Staay, Georg W.M. van der; Alen, Theo A. van; Ricard, Guenola; Gabaldón, Toni; Hoek, Angela H.A.M. van; Moon-van der Staay, Seung Yeo; Koopman, Werner J.H.; Hellemond, Jaap J. van; Tielens, Aloysius G.M.; Friedrich, Thorsten; Veenhuis, Marten; Huynen, Martijn A.; Hackstein, Johannes H.P.

    2005-01-01

    Hydrogenosomes are organelles that produce ATP and hydrogen, and are found in various unrelated eukaryotes, such as anaerobic flagellates, chytridiomycete fungi and ciliates. Although all of these organelles generate hydrogen, the hydrogenosomes from these organisms are structurally and

  15. Hospital waste management and other small producers

    International Nuclear Information System (INIS)

    Herbst, H.; Roy, J.C.

    1992-01-01

    This paper describes waste management in hospitals and other waste producers. Low-level radioactive wastes are collected by ANDRA (French Agency for radioactive waste management) and informations on waste processing or regulations on radiation sources are given

  16. How To Produce and Characterize Transgenic Plants.

    Science.gov (United States)

    Savka, Michael A.; Wang, Shu-Yi; Wilson, Mark

    2002-01-01

    Explains the process of establishing transgenic plants which is a very important tool in plant biology and modern agriculture. Produces transgenic plants with the ability to synthesize opines. (Contains 17 references.) (YDS)

  17. Strategies of development of European power producers

    International Nuclear Information System (INIS)

    Heddebaut, D.

    2007-12-01

    This economical study answers the following questions: what is the dynamics of European power markets? What is the relative competitiveness of the different power production means? What are the determining factors of electricity wholesale prices? Who are the operators the most threatened by the rise of wholesale prices? To what extend power producers are impacted by the CO 2 constrain? Who are the most efficient producers? The analysis is based on 18 of the most representative groups of the European electric utilities. The first volume of the study presents the strategic perspectives of European power producers: dynamics and basic characteristics of European power markets, strategic options of European operators, typology and financial results of European power producers, scenarios of market reorganization according to Eurostaf (possible mega-mergers in the future, competition). Volume 2 makes a detailed analysis of the positioning and perspectives of the 18 selected groups: key figures, sourcing strategies, production means management, Eurostaf's diagnosis. (J.S.)

  18. Petroleum term markets and OPEC producers countries

    International Nuclear Information System (INIS)

    Bensarsa, F.

    1994-01-01

    The situation of petroleum producers countries in front of term markets is described. With an economics liberalization, policy configuration changing the energetic balance (increasing of american imports, of asiatic demand and developing countries; decreasing of russian production), a more efficient technology, a right management of energetic resources with energy economy, renewable energies and non polluting energies, it is difficult for producers countries to resist at the pressure of financing tools, more and more modern and efficient as they are term markets

  19. Produced Water Management and Beneficial Use

    International Nuclear Information System (INIS)

    Brown, Terry; Frost, Carol; Hayes, Thomas; Heath, Leo; Johnson, Drew; Lopez, David; Saffer, Demian; Urynowicz, Michael; Wheaton, John; Zoback, Mark

    2007-01-01

    Large quantities of water are associated with the production of coalbed methane (CBM) in the Powder River Basin (PRB) of Wyoming. The chemistry of co-produced water often makes it unsuitable for subsequent uses such as irrigated agriculture. However, co-produced waters have substantial potential for a variety of beneficial uses. Achieving this potential requires the development of appropriate water management strategies. There are several unique characteristics of co-produced water that make development of such management strategies a challenge. The production of CBM water follows an inverse pattern compared to traditional wells. CBM wells need to maintain low reservoir pressures to promote gas production. This need renders the reinjection of co-produced waters counterproductive. The unique water chemistry of co-produced water can reduce soil permeability, making surface disposal difficult. Unlike traditional petroleum operations where co-produced water is an undesirable by-product, co-produced water in the PRB often is potable, making it a highly valued resource in arid western states. This research project developed and evaluated a number of water management options potentially available to CBM operators. These options, which focus on cost-effective and environmentally-sound practices, fall into five topic areas: Minimization of Produced Water, Surface Disposal, Beneficial Use, Disposal by Injection and Water Treatment. The research project was managed by the Colorado Energy Research Institute (CERI) at the Colorado School of Mines (CSM) and involved personnel located at CERI, CSM, Stanford University, Pennsylvania State University, the University of Wyoming, the Argonne National Laboratory, the Gas Technology Institute, the Montana Bureau of Mining and Geology and PVES Inc., a private firm

  20. Produced Water Management and Beneficial Use

    Energy Technology Data Exchange (ETDEWEB)

    Terry Brown; Carol Frost; Thomas Hayes; Leo Heath; Drew Johnson; David Lopez; Demian Saffer; Michael Urynowicz; John Wheaton; Mark Zoback

    2007-10-31

    Large quantities of water are associated with the production of coalbed methane (CBM) in the Powder River Basin (PRB) of Wyoming. The chemistry of co-produced water often makes it unsuitable for subsequent uses such as irrigated agriculture. However, co-produced waters have substantial potential for a variety of beneficial uses. Achieving this potential requires the development of appropriate water management strategies. There are several unique characteristics of co-produced water that make development of such management strategies a challenge. The production of CBM water follows an inverse pattern compared to traditional wells. CBM wells need to maintain low reservoir pressures to promote gas production. This need renders the reinjection of co-produced waters counterproductive. The unique water chemistry of co-produced water can reduce soil permeability, making surface disposal difficult. Unlike traditional petroleum operations where co-produced water is an undesirable by-product, co-produced water in the PRB often is potable, making it a highly valued resource in arid western states. This research project developed and evaluated a number of water management options potentially available to CBM operators. These options, which focus on cost-effective and environmentally-sound practices, fall into five topic areas: Minimization of Produced Water, Surface Disposal, Beneficial Use, Disposal by Injection and Water Treatment. The research project was managed by the Colorado Energy Research Institute (CERI) at the Colorado School of Mines (CSM) and involved personnel located at CERI, CSM, Stanford University, Pennsylvania State University, the University of Wyoming, the Argonne National Laboratory, the Gas Technology Institute, the Montana Bureau of Mining and Geology and PVES Inc., a private firm.