Isotopic evidence of non-thermalized neutron irradiation in solar-gas-rich meteorites: Possibility of the interaction with solar neutrons and activity from the early Sun
Isotopic evidence of non-thermalized neutron irradiation in solar-gas-rich meteorites: Possibility of the interaction with solar neutrons and activity from the early Sun
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DOI：
10.1016/j.epsl.2009.06.006
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发表时间：
2009-07
影响因子：
5.3
通讯作者：
H. Hidaka;S. Yoneda
中科院分区：
文献类型：
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作者：
H. Hidaka;S. Yoneda
地外材料中的 150Sm/149Sm 和 158Gd/157Gd 同位素位移提供了宇宙射线与材料表面相互作用引起的中子俘获反应发生的证据。卡波埃塔陨石（被称为富含太阳气体的陨石）化学浸出液的 Sm 和 Gd 同位素位移显示出清晰的中子俘获记录，对应的中子注量高达 9.0×1015n cm−2。来自卡波埃塔的两个部分的中子注量强度显着超过了在传输到地球期间宇宙射线照射时的预期强度。此外，Sm和Gd同位素位移的组合（定义为εSm/εGd以了解中子能谱）显示了卡波埃塔某些成分（εSm/εGd=1.9±0.5和1.9±0.7）与其他陨石和月球样本（εSm/εGd=0.4-0.9）不同的中子辐照环境。卡波埃塔的钐和钆同位素数据表明，来自早期太阳的非热化中子的辐射能量超过 1 eV。
150Sm/149Sm and158Gd/157Gd isotopic shifts in extraterrestrial materials provide evidence of the occurrence of neutron capture reactions caused by the interaction of cosmic rays with the surface of the materials. The Sm and Gd isotopic shifts of chemical leachates from the Kapoeta meteorite, known as a solar-gas-rich meteorite, show a clear neutron capture record corresponding to the neutron fluence up to 9.0×1015n cm−2. The intensities of the neutron fluences of two fractions from Kapoeta significantly exceed what is expected from the time for cosmic ray irradiation during the transit to Earth. Furthermore, the combination of Sm and Gd isotopic shifts, defined as εSm/εGdto understand the neutron energy spectrum, shows a different neutron irradiation environment for certain components of Kapoeta (εSm/εGd=1.9±0.5, and 1.9±0.7) from those of other meteorites and lunar samples (εSm/εGd=0.4–0.9). The isotopic data of Sm and Gd from Kapoeta suggest the irradiation of non-thermalized neutrons with the energies over 1 eV from the early Sun.