Sensitivity studies of spin cut-off models on fission fragment observables

L Thulliez,O Serot,O Litaize

doi:10.1051/epjconf/201611110003

Abstract

A fission fragment de-excitation code, FIFRELIN, is being developed at CEA Cadarache. It allows probing the characteristics of the prompt emitted particles, neutrons and gammas, during the de-excitation process of fully accelerated fission fragments. The knowledge of the initial states of the fragments is important to accurately reproduce the fission fragment observables. In this paper a sensitivity study of various spin cut-off models, completely defining the initial fission fragment angular momentum distribution has been performed. This study shows that the choice of the model has a significant impact on gamma observables such as spectrum and multiplicity and almost none on the neutron observables.

Highlights

During the fission fragment de-excitation, nuclei emit neutrons and gammas to loose their excitation energy and angular momentum in order to reach their ground state. The properties of those prompt emitted particles is of particular interest for nuclear reactors, for example to quantify the damage they can cause on the nuclear reactor vessel which has a direct impact on its lifetime
A Monte-Carlo computer code named FIFRELIN [1] [2] developed at CEA-Cadarache allows studying nuclear fission through the nuclear fission fragment de-excitation process
In this work the impact of spin cut-off models for initial spin distribution on fission observables was studied through the spontaneous fission of 252Cf

Summary

Introduction

During the fission fragment de-excitation, nuclei emit neutrons and gammas to loose their excitation energy and angular momentum in order to reach their ground state. If results related to major observables are in good agreement with available data, other calculated observables, which could not be measured, could be legitimately considered as pertinent This confers to FIFRELIN a predictive power. This paper will focus on the impact of the spin cut-off parameter models which defined the total angular momentum distribution from which the initial spins of the fragments are sampled. This entity mainly drives the characteristics of gammas such as their energy, their multiplicity and their spectrum.

Spin cut-off models involved in the initial spin distribution

Impact of spin cut-off models on fission observables

Neutron observables

Findings

Conclusion