Arid
DOI10.1016/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
ISSN0168-583X
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
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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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