Measurements of keV-Neutron capture cross sections and capture gamma-ray spectra of 74,76,78,80,82Se

Abstract

ABSTRACT The neutron capture cross sections and capture γ -ray spectra of 74,76,78,80,82Se were measured in a region from 15 to 100 keV and around 550 keV. A neutron time-of-flight method was used with a ns-pulsed neutron source based on the 7Li(p,n)7Be reaction and a large anti-Compton NaI(Tl) γ -ray spectrometer. A pulse-height weighting technique was applied to the observed γ -ray pulse-height spectra to obtain capture yields. The capture cross sections of 74,76,78,80Se were derived with uncertainties from 4.0 to 5.5% and those of 82Se were derived with uncertainties of 6.5–27% by using the standard capture cross sections of 197Au. The present results of 78,82Se were the first experimental ones above the resolved resonance region. The present results were compared with previous measurements and the evaluated values in JENDL-5.0 and ENDF/B-VIII.0. The evaluations of JENDL-5.0 differ from the present results of 74,76,78,80Se and 82Se by 0.9–51% and 6.9–120%, respectively. The capture γ -ray spectra of 74,76,78,80,82Se were derived by unfolding the observed capture γ -ray pulse-height spectra. The present results were the first experimental ones in the keV region.