Fission barriers in neutron-proton isospin plane for heavy neutron-rich nuclei

TL;DR

This paper investigates how fission barriers in heavy neutron-rich nuclei depend on the fission path in the neutron-proton quadrupole plane, using a Skyrme-Hartree-Fock + BCS approach, and finds that the barrier heights are consistent across different constraining operators.

Contribution

It demonstrates that the standard method of calculating fission barriers with the mass quadrupole operator is valid even for neutron-rich nuclei, supported by comparative analysis.

Findings

Fission barrier heights are similar across different constraining operators.

The method is applicable to neutron-rich uranium isotopes relevant to r-process nucleosynthesis.

Proton and neutron deformation parameters vary along fission paths.

Abstract

We discuss the sensitivity of fission barrier for heavy neutron-rich nuclei to fission paths in the two dimensional neutron-proton quadrupole plane. To this end, we use the constrained Skyrme-Hartree-Fock + BCS method, and examine the difference of fission barriers obtained with three constraining operators, that is, the neutron, proton, and mass quadrupole operators. We investigate $^{220}$U, $^{236}$U, and $^{266}$U, %from proton-rich to neutron-rich uranium isotopes, that is relevant to r-process nucleosynthesis. We find that the fission barrier heights are almost the same among the three constraining operators even for neutron-rich nuclei, indicating that the usual way to calculate fission barriers with the mass quadrupole operator is well justified. We also discuss the difference between proton and neutron deformation parameters along the fission paths.