Deblurring fission fragment mass distributions

TL;DR

This paper introduces a deblurring technique based on the Richardson-Lucy algorithm to extract pre-neutron emission fission fragment mass distributions from measured data, improving the accuracy of fission models.

Contribution

It applies a novel deblurring method to fission fragment data, avoiding assumptions about distribution shapes, and enhances the inputs for fission modeling codes.

Findings

Deblurred distributions better represent pre-neutron emission data.

Improved inputs lead to more accurate fission modeling results.

Method successfully applied to $^{252}$Cf spontaneous fission data.

Abstract

Measurements of fission fragment mass distributions provide valuable insights into the properties of fissioning systems and the dynamics of the fission process. Pre-neutron emission distributions, essential for fission fragment evaporation codes like \cgmf{}, are extracted from distributions that are always measured after neutron emission, as the time scale of the emission of prompt fission neutrons is too short for direct measurement before the emission. However, obtaining accurate pre-neutron emission distributions requires methods that eliminate the effects of mass resolution and detector efficiency. We propose a deblurring technique based on the Richardson-Lucy (RL) algorithm, commonly used in optics for image restoration, to correct for these experimental effects. The RL algorithm uses the measured mass distributions and a transfer matrix to perform iterative deconvolution. The advantage of this method over others is that it does not assume any predefined shape such as a sum of Gaussians, as in \cgmf{}, for the distributions. In this paper, we apply the algorithm to the fission fragment mass distributions measured in the spontaneous fission of $^{252}$Cf to extract pre-neutron emission fission fragment mass distributions. The results from deblurring are then used as inputs to \cgmf{}, and we compare the \cgmf{} results obtained using deblurring inputs with the default \cgmf{} results.