The Au 197(n, γ)Au 198 cross section from 13 keV to 683 keV

Abstract

Cross section for the Au 197(n, γ)Au 198 reaction have been measured with an average absolute uncertainty of 4.7% and an average relative uncertainty of 3.5% at 14 neutron energies in the range from 13 keV to 683 keV. The V 51(p, n)Cr 51 reaction was used as a neutron source in these measurements. An 0.013 cm thick spherical shell of gold was irradiated at each energy by neutrons produced by proton bombardment of a thin vanadium target placed at the centre of the spherical shell. The neutron flux was determined by counting the Cr 51 activity in the vanadium target and the number of capture interactions in the gold was found by counting the Au 198 activity. Both activities were measured with a calibrated 10.2 cm × 10.2 cm NaI scintillation spectrometer. The neutron energy resolution, caused principally by the target thickness and the kinematic energy spread over the sphere, increased with energy from about 10 keV (half the total neutron energy spread) at a neutron energy of 13 keV to about 74 keV at the highest energy point. As a check on the results obtained with neutrons produced by the V 51(p, n)Cr 51 reaction, one cross-section measurement was made at a neutron energy of 39 keV with the Cu 65(p, n)Zn 65 reaction as the neutron source.