Evidence of non-statistical neutron emission following beta-decay near doubly magic 132Sn

It assumed that beta-delayed neutron emission proceeds statistically through the intermediate compound nucleus stage. Neutron emission probabilities from unbound states in 134Sn to known low-lying, single-particle states in 133Sn were measured. Detailed analysis of the neutron-emission branching ratios revealed discrepancies between the statistical model description and data. Our results suggest that a possible violation of the compound nucleus assumption may occur in beta-delayed neutron emission in nearly doubly-magic nuclei. This impacts the neutron emission probabilities and other properties of nuclei participating in the r-process. We propose a revised model of neutron emission, which links the observed neutron emission probabilities to nuclear shell effects using the doorway state concept.