Correlation between fission tracks and fission type xenon in meteoritic Whitlockite

Abstract

Whitlockite from the St. Severin chondrite, previously shown to contain excess fission tracks, is here shown to have a large concentration of excess neutron-rich xenon isotopes. The concentration of excess heavy Xe in the whitlockite is about twenty-five times that calculated from the track density. An isotopic spectrum is deduced that is identical to the spectrum calculated previously for excess heavy xenon in the Pasamonte achondrite. These results uniquely associate this xenon spectrum with in situ fission in meteorites. Chemical arguments support the correlation of this with Pu^(244). Identification of the fissioning nucleus as Pu^(244) gives Pu^(244)/U^(238) ≈ 1/30. Neither 'sudden' nor 'uniform' nucleosynthetic models give consistent solutions for Pu^(244)/U^(238) and U^(235)/U^(238).

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