Affiliation:
1. Max-Planck-Institut für Kernphysik, Heidelberg
Abstract
The stable He-, Ne-, Ar-, Kr- and Xe-isotopes and the Te-, K-, U-, Th- and Se-concentrations in a Precambrian bismuth-tellurium ore have been measured. We have found an age of 0.53 x 109 y with K-Ar, 0.55 x 109 y with U/Th-He4 and 1.56 x 109 y by the U-Xe136 method.
The Xe131-excess and part of the Xe129-excess result from n-capture and subsequent decay of Te128and Te130. The remaining part of the Xe129-excess and the high U-Xe136 age give evidence for a higher neutron flux before the last cooling of the ore. The tellurium was probably associated with much more uranium than now. Before 0.54 x 109 y, differentiation of this uranium occured. Moreover, He and Ar but not all of the Xe were removed at this time. After cooling, the Xe129excess was formed by the decay of the long-lived I129 which had been formed from (n,γ) reactions on Te128 by the higher neutron flux.
From the excess in Xe130, a half life for the double β-decay of Te130 of 6.2 x 1020 y is calculated.
Besides fission-Kr, there is an excess of Kr with atmospheric composition and in addition an excess of Kr82 and Kr83 also. From the Kr82-excess and the selenium content a lower limit for the Se82-double β-decay half life of T1/2≥ 1018 y is calculated. No evidence is given for Ar38 from U-fission.
Subject
Physical and Theoretical Chemistry,General Physics and Astronomy,Mathematical Physics
Cited by
20 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献