<国立科学博物館研究報告>日本の球粒隕石中の宇宙線生成 ^<26>Al と ^<53>Mn(英文)

概要

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Cosmic-ray-produced long-lived radioactive nuclides, ^<26>Al and ^<53>Mn, were determined in eighteen chondrites which fell and recovered in Japan, by nondestructive γ-ray spectrometry and neutron activation analyses, respectively. Data were compared with those of published spallogenic neon data obtained from the same chondrite specimens as well as published ^<53>Mn data. Generally, the correlation of ^<26>Al and ^<53>Mn with ^<22>Ne/^<21>Ne show normal trends in chondritic meteorites, except the Aomori, Kamiomi, Numakai and the gas-rich chondrites Nio and Fukutomi. Cosmic-ray exposure ages of those chondrites were calculated from data of ^<53>Mn activities and ^<53>Mn/^<26>Al pairs and were compared with conventional ^<21>Ne ages. Obtained ages by the present methods are generally in good agreement with ^<21>Ne ages. Discrepancies between ^<26>Al data and data of ^<53>Mn and apallogenic neon isotopic ratio of Kamiomi and between present ^<53>Mn data and published one of Satsuma (Kyushu) are due to the different sampling positions. High ^<21>Ne age compared with the present data in the Aomori could be explained by multi-irradiation model while low ^<21>Ne age observed in the Numakai are probably result of the gas loss by heavy shock of this meteorite in space.
国立科学博物館の論文
1989-12-22