The differences (?i) in the abundance ratios of the stable xenon isotopes in meteorites and in the earth's atmosphere indicate that the latter contains an excess of fissiogenic xenon. It is postulated that the “extinct” transuranium elements, such as Pu244 and Cm247, played important roles in the production of the fissiogenic xenon in the earth's atmosphere. The time interval (?) between the nucleosynthesis and the formation of the earth has been calculated from the values of ?i. If it is assumed that the contribution from the Cm247 spontaneous fission and the U235 neutron-induced fission was negligible, a value of ? = 4.8 × 108 years is obtained for the single event model and a value of ? = 0.52 × 108 years for the continuous synthesis model.
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