Strong gamma-ray emission from neutron unbound states populated in beta-decay: Impact on (n,gamma) cross-section estimates

Total absorption gamma-ray spectroscopy is used to measure accurately the intensity of gamma emission from neutron-unbound states populated in the β-decay of delayed-neutron emitters. From the comparison of this intensity with the intensity of neutron emission one can deduce information on the (n,γ) cross section for unstable neutron-rich nuclei of interest in r process abundance calculations. A surprisingly large gamma branching was observed for a number of isotopes. The results are compared with Hauser-Feshbach calculations and discussed.