A measurement of the averaged cross section for the 232Th(n, 2n) 231Th reaction with a fission plate

Abstract

232Th(n, 2n) 231Th reaction cross sections averaged over the fission neutron spectrum have been measured by use of a 90% enriched uranium fission plate. The 232Th sample and fast neutron monitor foils of Mg, Ti and Ni were irradiated with fission neutrons from the fission plate. The irradiated 232Th sample was chemically purified. Gamma rays from these samples were measured with a 30 cm 3 Ge(Li) detector. The cross section value obtained is 15.5 ± 1.2 mb, and agrees with the predicted values by Pearlstein and Zijp et al. within the experimental errors. The half-life of 231Th was measured. A value of 25.76±0.21 h was obtained.