Systematic Study of Fission Barriers of Excited Superheavy Nuclei

TL;DR

This study systematically investigates how fission barriers of superheavy nuclei depend on excitation energy using advanced self-consistent models, revealing rapid changes influenced by shell effects and predicting fission mode transitions at high energies.

Contribution

It provides a comprehensive analysis of fission barriers in superheavy nuclei considering triaxial and reflection asymmetry effects with finite-temperature methods.

Findings

Fission barriers decrease rapidly with excitation energy, especially near N=164 and N=184.

Shell effects significantly influence fission barrier stability at high excitation energies.

Predicted transition from asymmetric to symmetric fission modes at high excitation energies for specific nuclei.

Abstract

A systematic study of fission-barrier dependence on excitation energy has been performed using the self-consistent finite-temperature Hartree-Fock+BCS (FT-HF+BCS) formalism with the SkM* Skyrme energy density functional. The calculations have been carried out for even-even superheavy nuclei with Z ranging between 110 and 124. For an accurate description of fission pathways, the effects of triaxial and reflection-asymmetric degrees of freedom have been fully incorporated. Our survey demonstrates that the dependence of isentropic fission barriers on excitation energy changes rapidly with particle number, pointing to the importance of shell effects even at large excitation energies characteristic of compound nuclei. The fastest decrease of fission barriers with excitation energy is predicted for deformed nuclei around N=164 and spherical nuclei around N=184 that are strongly stabilized by ground-state shell effects. For nuclei 240Pu and 256Fm, which exhibit asymmetric spontaneous fission, our calculations predict a transition to symmetric fission at high excitation energies due to the thermal quenching of static reflection asymmetric deformations.