To fission or not to fission

TL;DR

This paper models the fission-fragments mass-yield of 236U using a collective Hamiltonian approach, highlighting the importance of the neck degree of freedom in determining the mass distribution.

Contribution

It introduces a four-dimensional model incorporating shape and neck degrees of freedom to predict fission fragment distributions.

Findings

Neck degree of freedom significantly influences mass distribution.

The model successfully reproduces experimental mass-yield data.

Shape parametrization impacts the accuracy of fission predictions.

Abstract

The fission-fragments mass-yield of 236U is obtained by an approximate solution of the eigenvalue problem of the collective Hamiltonian that describes the dynamics of the fission process whose degrees of freedom are: the fission (elongation), the neck and the mass-asymmetry mode. The macroscopic-microscopic method is used to evaluate the potential energy surface. The macroscopic energy part is calculated using the liquid drop model and the microscopic corrections are obtained using the Woods-Saxon single-particle levels. The four dimensional modified Cassini ovals shape parametrization is used to describe the shape of the fissioning nucleus. The mass tensor is taken within the cranking-type approximation. The final fragment mass distribution is obtained by weighting the adiabatic density distribution in the collective space with the neck-dependent fission probability. The neck degree of freedom is found to play a significant role in determining that final fragment mass distribution.