Spallation cross sections for long-lived radionucleides in iron and light nuclei

Abstract

The cross sections for the formation of the long-lived radionucleides Be¹⁰, Si³², K⁴⁰, Ar⁴² and Ti⁴⁴ and a few short-lived nucleides in Fe by 730 MeV protons and of Be¹⁰ in C, N and O by 220 MeV protons have been measured. These data have been obtained for interpretation of the observed results of cosmic ray induced radioactivity in meteorites and on the earth. Over a wide range of mass numbers, the measured cross sections in iron for various radioactive nucleides, especially those close to the nuclear stability line, can be expressed fairly accurately by a semi-empirical relation first discussed by Rudstam. Using this relation, we have calculated reasonable values for the half-lives of the radioactive nucleides Si³² and Ti⁴⁴, for which only crude estimates were available as yet.