The measurement of neutron activation cross sections in the energy range 3.5 Mev to 6.0 Mev

Abstract

A measurement of the 46•47•48Ti(n,n)46•47•48sc reaction cross-sections has been performed relative to the U-235 fission cross-sections over the neutron energy range of 3.5 Mev to 6.0 Mev. e q' J ir 2 d for f J. I J < '!a 1 >.sis The uranium-235 content,< was aetermined from both 27/ and low geometry alpha-particle assay. Fissions from the U-235 standard were detected in a low mass parallel-plate ionisation chamber. To provide a satisfactory neutron flux, a deuterium gas taget was designed to withstand up to three times the maximum beam power densities Permissible in conventional gas targets. The gamma-ray activities induced in the irradiated samples were determined using a 7.62 em x 7.62 em Nai(TI) detector. The gamma-ray detection efficiencies were corrected for sample self­ scattering and self-absorption using the Monte Carlo method. A second Monte Carlo program was developed to correct for irradiation geometry. Corrections were applied for neutron scattering within the sample and fission chamber, and the thermal and back­ ground neutrons. The present measurements are in agreement with other measurements, whilst nroviding greater accuracies.