Use of a total absorption gamma-ray spectrometer to measure ground-state β−-branching intensities

Abstract

A method has been developed to measure ground-state β −-branching intensities with the total absorption γ-ray spectrometer at the INEL ISOL facility. This spectrometer, which is used to measure β-feeding (or β-strength) distributions to excited states in neutron-rich fission-product nuclei, consists of a 25.4 cm diameter × 30.5 cm long well-type NaI(Tl) scintillation detector together with a Si β − detector located in the collection-tape transport line in the well. With this spectrometer operating in the β-γ coincidence mode as a 4πγ−β detector, ground-state β −-branching intensities are obtained from simple ratios of β−γ coincidence to β singles count rates together with additional, generally small, correction terms. Results obtained for 106Rh, 138–141Cs, 141–142Ba, 142–145La and 145Ce are presented and compared with existing data obtained with conventional nuclear spectroscopic methods.