Three-dimensional potential energy surface for fission of $^{236}$U within covariant density functional theory

TL;DR

This study calculates a detailed three-dimensional potential energy surface for $^{236}$U fission using covariant density functional theory, revealing coexistence of fission modes and fluctuations in fragment properties.

Contribution

It introduces a 3D PES calculation including the neck nucleon number, predicting coexistence of fission modes and extended scission lines affecting fragment energies and masses.

Findings

Coexistence of elongated and compact fission modes predicted.

The PES is very shallow over a large deformation range.

Fluctuations in total kinetic energies and fragment masses are observed.

Abstract

We have calculated the three-dimensional potential energy surface (PES) for the fission of compound nucleus $^{236}$U using the covariant density functional theory with constraints on the axial quadrupole and octupole deformations $(\beta_2, \beta_3)$ as well as the nucleon number in the neck $q_N$. By considering the additonal degree of freedom $q_N$, coexistence of the elongated and compact fission modes is predicted for $0.9\lesssim \beta_3 \lesssim 1.3$. Remarkably, the PES becomes very shallow across a large range of quadrupole and octupole deformations for small $q_N$, and consequently, the scission line in $(\beta_2, \beta_3)$ plane will extend to a shallow band, which leads to a fluctuation for the estimated total kinetic energies by several to ten MeV and for the fragment masses by several to about ten nucleons.