# Competing quasifission and asymmetric fusion-fission in neutron-deficient sub-lead nuclei

## TL;DR

This study investigates the influence of shell effects and reaction dynamics on fission fragment distributions in neutron-deficient sub-lead nuclei, revealing the significant role of quasifission and entrance channel effects.

## Contribution

It provides experimental evidence of quasifission in sub-lead nuclei and highlights the importance of entrance channel dynamics in interpreting fission data.

## Key findings

- Evidence of shell effects in mass distributions
- Observation of quasifission in Cl-induced reactions
- Entrance channel dynamics significantly affect fission outcomes

## Abstract

To disentangle the role of shell effects and dynamics, fission fragment mass distributions of $^{191}$Au, a nucleus in the newly identified island of mass asymmetric fission in the sub-lead region, have been measured down to excitation energy of $\approx$20 MeV above the fission barrier via two different entrance channels, viz. $^{16}$O+$^{175}$Lu and $^{37}$Cl+$^{154}$Sm reactions. Apart from having signature of the shell effects in both the cases, clear experimental evidence of quasifission has been observed in the mass distributions of the Cl induced reaction, that has also been substantiated by the theoretical calculations. This crucial evidence along with a systematic analysis of available experimental data has revealed that the dynamics in the entrance channel has significant influence on most of the reactions used earlier to explore the persistence of recently discovered mass asymmetry in $\beta$-delayed fission at low energy in this mass region, ignoring which might lead to ambiguity in interpreting the heavy-ion data.