Isotopic composition of gadolinium and neutron‐capture effects in some meteorites
Isotopic composition of gadolinium and neutron‐capture effects in some meteorites
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一些陨石中钆的同位素组成和中子俘获效应
DOI：
10.1029/jb075i014p02753
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发表时间：
1970
影响因子：
--
通讯作者：
Charles Arms
中科院分区：
文献类型：
--
作者：
O. Eugster;TE F.;D. Burnett;G. Wasserburg;Charles Arms
测定了一颗球粒陨石、两颗无球粒陨石和两颗铁陨石的硅酸盐包裹体中Gd的同位素组成。在校正了质量差别后，除诺顿县无球粒岩外，所有样品中的Gd显示出与陆地Gd相同的相对同位素丰度。这些结果确定了地球和这些陨石的微分积分热中子辐照的上限为3×10^（15）中子/ cm^2。从诺顿县无球粒岩中提取的Gd存在中子捕获效应。这些极有可能是由次级中子产生的，在这颗巨大的石陨石受到异常长时间的宇宙射线照射时。同位素异常对应的热中子通量为（6.3±0.9）×10^（15）中子/ cm^2。Gd^（160）、Gd^（158）、Gd^（157）、Gd^（156）、Gd^（155）、Gd^（154）和Gd^（152）的丰度百分比分别为21.863、24.835、15.652、20.466、14.800、2.1809和0.2029。由于精度更高，这些丰度应该取代目前接受的值。
The isotopic composition of Gd in one chondrite, two achondrites, and the silicate inclusions of two iron meteorites has been determined. When corrected for mass discrimination, Gd in all samples except the Norton County achondrite shows the same relative isotopic abundances as terrestrial Gd. These results set an upper limit of 3×10^(15) neutrons per cm^2 on a differential integrated thermal neutron irradiation of the earth and these meteorites. Neutron-capture effects are present in Gd extracted from the Norton County achondrite. These most probably have been produced by secondary neutrons during the exceptionally long cosmic ray exposure of this large stone meteorite. The isotopic anomalies correspond to an integrated thermal neutron flux of (6.3±0.9)×10^(15) neutrons per cm^2. The percent abundances of terrestrial Gd found in our work for Gd^(160), Gd^(158), Gd^(157), Gd^(156), Gd^(155), Gd^(154), and Gd^(152) are 21.863, 24.835, 15.652, 20.466, 14.800, 2.1809, and 0.2029, respectively. Because of the higher precision, these abundances should replace the currently accepted values.