Beta-delayed fission in the coupled Quasi-particle Random Phase Approximation plus Hauser-Feshbach approach

TL;DR

This paper presents a theoretical approach combining QRPA and Hauser-Feshbach models to calculate beta-delayed fission probabilities in heavy, neutron-rich nuclei, revealing high fission probabilities near the neutron dripline and potential for multi-chance fission.

Contribution

It introduces a coupled QRPA+HF model to predict beta-delayed fission and neutron emission probabilities, including multi-chance fission in neutron-rich nuclei.

Findings

High beta-delayed fission probabilities near 100% in certain heavy nuclei.

Identification of nuclei with large neutron emission and fission probabilities near the dripline.

Provision of a comprehensive table of branching ratios for future experimental use.

Abstract

Beta-delayed neutron emission and $\beta$-delayed fission ($\beta$df) probabilities were calculated for heavy, neutron-rich nuclei using the Los Alamos coupled Quasi-Particle Random Phase Approximation plus Hauser-Feshbach (QRPA+HF) approach. In this model, the compound nucleus is initially populated by $\beta$-decay and is followed through subsequent statistical decays taking into account competition between neutrons, $\gamma$-rays and fission. The primary output of these calculations includes branching ratios along with neutron and $\gamma$-ray spectra. We find a relatively large region of heavy nuclides where the probability of $\beta$df is near 100%. For a subset of nuclei near the neutron dripline, delayed neutron emission and the probability to fission are both large which leads to the possibility of multi-chance $\beta$df (mc-$\beta$df). We comment on prospective neutron-rich nuclei that could be probed by future experimental campaigns and provide a full table of branching ratios in ASCII format in the supplemental material for use in various applications.