| タイトル | Cosmogenic Samarium-150 and Calcium-41 in Norton County |
| 本文（外部サイト） | http://hdl.handle.net/2060/20100001649 |
| 著者（英） | Shih, C.-Y.; Klein, J.; Herzog, G. F.; Albrecht, A.; Masarik, J.; Middleton, R.; Ma, P.; Reedy, R. C.; Korschinek, G.; Garrison, D. H.; Nyquist, L. E.; Fink, D.; Bogard, D. D.; Reese, Y.; Rugel, G.; Faestermann, T. |
| 著者所属（英） | NASA Johnson Space Center |
| 発行日 | 2010-01-01 |
| 言語 | eng |
| 内容記述 | Though brecciated, the Norton County (NC) aubrite contains little or no trapped noble gas and has been widely assumed to have a simple if unusually long cosmic ray exposure (CRE), 115 Ma. One goal of this ongoing study of NC has been to search for signs of pre-irradiation as proposed. One may test for multiple stages of CRE by comparing thermal neutron fluences inferred from Ca-41 (t(sub 1/2)=0.1 Ma) activities, which reflect irradiation conditions over the last approximately 0.3 Ma, with those inferred from (stable) Sm isotope abundances, which integrate over the entire CRE history. In the case of a one-stage exposure the fluences should agree. We focus on these particular comparisons because the properties of NC - its long CRE exposure, relatively large size, and low iron concentration - all promised high production rates and ease of measurement. Previously, we reported on several cosmogenic nuclides in NC. Here we present new Ca-41 data, Sm isotope measurements, and comparisons with model calculations of cosmic ray production. |
| NASA分類 | Lunar and Planetary Science and Exploration |
| レポートNO | JSC-CN-19568
JSC-CN-19502 |
| 権利 | Copyright, Distribution as joint owner in the copyright |
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