Tritium-Diffusionsmessungen an protonenbestrahlten Proben des Eisenmeteoriten Sikhote-Alin

Abstract

Samples of the iron meteorite Sikhote Alin were irradiated in the synchrocyclotron at CERN by 600 MeV protons. A concentration of the radioactive isotopes Ar37 and tritium was produced by spallation from iron and nickel nuclei. Diffusion and extraction experiments showed a lack of the produced tritium which may either have been dissolved in the iron at higher temperatures or escaped by diffusion during the irradiation. Also some grains were completely dissolved chemically. The results were that most of the tritium diffused out of the samples during the irradiation, while only a neglectible amount of argon was lost by diffusion during the irradiation. Based on this result we could determine the diffusion parameter D/a2 at room temperature to be in the order of 10-9 sec-1. The activation energy is in the vicinity of 10 kcal/mol. From these values for the diffusion parameters it can be concluded that the meteorite lost most of the tritium within a few weeks after its fall.