Chlorine-36 produced by neutron capture in meteorites

Abstract

The existence of the long-lived radionuclide chlorine-36 in iron meteorites, where it is produced by the spallation of the metal during its exposure to cosmic rays in space, is now well known. The measurements of cosmogenic ³⁶Ar and ³⁶Cl so produced permit one to calculate the so-called cosmic-ray exposure age of a meteorite. In this communication the results of experiments which show that in large iron meteorites the production of this nuclide also takes place via the reaction ³⁵Cl(n,γ)³⁶Cl on the lawrencite inclusions in the metal are presented. This result is of significance in deducing the history of meteorites from the investigation of cosmic-ray reaction products.