Nuclear spectrometry of 9.6 h 196Aum2 and the reaction of 197Au with fast neutrons

Abstract

The neutron activation of gold is the basis of an implosion performance diagnostic at the National Ignition Facility at Lawrence Livermore National Laboratory. In support of this diagnostic, a series of γ-ray spectrometric measurements of the decay of 196Aum2 (Jπ = 12−) was performed to improve the currently accepted literature values of the nuclear data associated with its half-life, γ-ray energies, and γ-ray intensities. It was determined that 196Aum2 decays with a half-life of 9.603 h ± 0.23%. The relative intensities of the γ rays emitted during its decay were also measured, and an absolute decay branch of 0.3352 ± 2.9% was determined for the emission of the 188.2 keV photon, which arises from a nuclear transition whose multipolarity is predominantly M1. Properties of other products arising in the reaction of 197Au with fast neutrons were measured, as were selected production cross sections. The 196Aum2/196Aug isomer ratio measured in the 197Au(n, 2n) reaction at 14.1 MeV was found to be 0.0731 ± 2.6%.