$\beta$-delayed fission in $r$-process nucleosynthesis

Understand

We present $\beta$-delayed neutron emission and $\beta$-delayed fission calculations for heavy, neutron-rich nuclei using the coupled Quasi-Particle Random Phase Approximation plus Hauser-Feshbach (QRPA+HF) approach.

• From the initial population of a compound nucleus after $\beta$-decay, we follow the statistical decay taking into account competition between neutrons, $\gamma$-rays, and fission.
• We find a region of the chart of nuclides where the probability of $\beta$-delayed fission is $\sim100$%, that likely prevents the production of superheavy elements in nature.
• For a subset of nuclei near the neutron dripline, neutron multiplicity and the probability of fission are both large, leading to the intriguing possibility of multi-chance $\beta$-delayed fission, a new decay mode for extremely neutron-rich heavy nuclei.