Chlorine-36 produced by neutron capture in meteorites

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