Shell effects and multi-chance fission in the sub-lead region

Abstract

Within the recently developed five-dimensional Langevin approach for the description of fission of heavy nuclei, we have calculated the fission fragments mass and kinetic energy distributions for the fission of $^{180}$Hg and $^{190}$Hg formed in the reactions $^{36}$Ar +$^{144}$Sm $\Rightarrow$ $^{180}$Hg and $^{36}$Ar +$^{154}$Sm $\Rightarrow$ $^{190}$Hg at few excitation energies and found very good agreement between the calculated and experimental results. Special attention was paid to the accurate description of the dependence of shell effects on the excitation energy. It was shown that the effect of multi-chance fission on the mass distribution is noticeable only at small excitation energies. The kinetic energy distributions are more sensitive to pre-scission neutron emission.