Evidence for Extinct ^(36)Cl from Excess ^(36)Ar in Allende Sodalite

Abstract

Introduction: Excesses of ^(36)S have previously been reported in sodalite (Na_8Al_6Si_6O_(24)Cl_2) and wadalite (Ca_6Al_5Si_2O_(16)Cl_3) in CAI andchondrules from the Allende and Ningqiang meteorites and used to infer the presence of ^(36)Cl (half-life 3 x 10^5 a) in the early solar system. In spite of the fact that ^(36)Cl decays predominantly (98%) to ^(36)Ar, all attempts to locate the very large amounts of ^(36)Ar implied by these ^(36)S excesses have been negative. Here we present results of a new method to identify ^(36)Ar from ^(36)Cl decay, based on low fluence fast neutron activation.

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