The description of the excitation energy sharing in nuclear fission within the Langevin approach

F.A Ivanyuk,S Chiba,N Carjan,S Oberstedt

doi:10.1051/epjconf/202125600007

Abstract

We apply the four-dimensional Langevin approach to the description of fission of 235U by neutrons and calculate the dependence of the excitation energy of fission fragments on their mass number. For this we run the Langevin equations until the compound nucleus splits into two separated fragments. This is possible since the we used in this work two-center shell model shape parametrization that describes well both compact and separated shapes. The excitation energies of each fragment are calculated assuming that the temperatures of both fragments are the same. The deformation energy of the fragment immediately after scission is added to its excitation energy. The saw-tooth structure of the dependence neutron multiplicity on the fragment’s mass number in reaction 235U + n at En = 5 Mev is qualitatively reproduced.

Highlights

One of the most successful approaches to the description of fusion-fission reactions and the fission process is the approach based on the Langevin equations for the shape degrees of freedom
We have found a very clear correlation between the neutron multiplicity and the deformation of fission fragment just before scission
In this work we exploit the found correlation between the neutron multiplicity and the deformation of fission fragment in order to clarify the reason for the saw-tooth structure of neutron multiplicity and its dependence on the excitation energy

Summary

Introduction

One of the most successful approaches to the description of fusion-fission reactions and the fission process is the approach based on the Langevin equations for the shape degrees of freedom. In this approach instead of co-ordinates of individual nucleons one introduces the parametrization of the shape of nuclear surface and solves the dynamical equations for the time evolution of deformation parameters and conjugated momenta. In this work we exploit the found correlation between the neutron multiplicity and the deformation of fission fragment in order to clarify the reason for the saw-tooth structure of neutron multiplicity and its dependence on the excitation energy

The model

Numerical results

Summary