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DOI | 10.1016/j.nimb.2007.01.204 |
Cosmogenic Ca-41 in diogenites: Production rates, pre-atmospheric size and terrestrial ages | |
Welten, K. C.; Hillegonds, D. J.; Masarik, J.; Nishiizumi, K. | |
通讯作者 | Welten, K. C. |
会议名称 | 10th International Conference on Accelerator Mass Spectrometry |
会议日期 | SEP 05-10, 2005 |
会议地点 | Berkeley, CA |
英文摘要 | We measured concentrations of cosmogenic Ca-41 in 37 diogenites, including 8 falls and 29 Antarctic finds, using accelerator mass spectrometry (AMS). The measured Ca-41 concentrations in falls range from 2.8 to 9.3 dpm/kg, those in Antarctic finds range from 1.6 to 28 dpm/kg. The Ca-41 concentrations in four of the falls agree within 10% with estimated saturation values based on spallation from Ti, Cr, Mn and the main target element, Fe. Four other diogenite falls and several Antarctic finds show elevated Ca-41 concentrations, which are attributed to capture of thermal neutrons on Ca-40. The neutron-capture Ca-41 contributions range from 0.1 to 1.5 dpm/g Ca. Monte Carlo based model calculations show that contributions of neutron-capture Ca-41 are negligible (< 0.05 dpm/g Ca) in diogenites with pre-atmospheric radii < 20 cm, but become dominant in diogenites larger than 30 cm in radius and reach a maximum value of similar to 5.6 dpm/g Ca in the center of objects with radii of 80-100 cm. The contributions of neutron-capture Ca-41 in diogenites were used to constrain their pre-atmospheric radii. Many Antarctic diogenites show low Ca-41 concentrations, up to 60% below the saturation value determined for falls. From these low Ca-41 concentrations we derive terrestrial ages up to similar to 135 kyr. We compare these terrestrial ages with those of other Antarctic achondrites and Antarctic chondrites and discuss the role of terrestrial weathering in limiting the lifetime of meteorites failing in different environments, i.e. Antarctic versus hot desert conditions. (c) 2007 Elsevier B.V. All rights reserved. |
英文关键词 | cosmogenic nuclides Ca-41 diogenites production rate pre-atmospheric size Antarctic meteorites terrestrial age |
来源出版物 | NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS |
ISSN | 0168-583X |
出版年 | 2007 |
卷号 | 259 |
期号 | 1 |
页码 | 653-662 |
出版者 | ELSEVIER SCIENCE BV |
类型 | Article;Proceedings Paper |
语种 | 英语 |
国家 | USA;Slovakia |
收录类别 | CPCI-S ; SCI-E |
WOS记录号 | WOS:000247535600117 |
WOS关键词 | ACCELERATOR MASS-SPECTROMETRY ; ANTARCTIC METEORITES ; COSMIC-RAY ; EXPOSURE HISTORY ; NEUTRON-FLUX ; SPALLATION ; GRANT ; LLNL |
WOS类目 | Instruments & Instrumentation ; Nuclear Science & Technology ; Physics, Atomic, Molecular & Chemical ; Physics, Nuclear |
WOS研究方向 | Instruments & Instrumentation ; Nuclear Science & Technology ; Physics |
资源类型 | 会议论文 |
条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/296655 |
作者单位 | (1)Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA;(2)Lawrence Livermore Natl Lab, Ctr Accelerator Mass Spectrometry, Livermore, CA 94550 USA;(3)Comenius Univ, Dept Nucl Phys, Bratislava, Slovakia |
推荐引用方式 GB/T 7714 | Welten, K. C.,Hillegonds, D. J.,Masarik, J.,et al. Cosmogenic Ca-41 in diogenites: Production rates, pre-atmospheric size and terrestrial ages[C]:ELSEVIER SCIENCE BV,2007:653-662. |
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