Fission-fragment mass distributions from strongly damped shape evolution

TL;DR

This paper demonstrates that modeling fission shape evolution as a random walk on potential-energy surfaces within the Smoluchowski framework effectively reproduces experimental fragment mass distributions, highlighting the robustness and potential of this approach.

Contribution

It introduces a physically justified Smoluchowski-based model for fission shape evolution and explores its sensitivity to model parameters, improving understanding of mass distribution predictions.

Findings

Random walks on potential-energy surfaces match experimental data.

Mass yields are robust to model variations.

Including anisotropic dissipation refines results.

Abstract

Random walks on five-dimensional potential-energy surfaces were recently found to yield fission-fragment mass distributions that are in remarkable agreement with experimental data. Within the framework of the Smoluchowski equation of motion, which is appropriate for highly dissipative evolutions, we discuss the physical justification for that treatment and investigate the sensitivity of the resulting mass yields to a variety of model ingredients, including in particular the dimensionality and discretization of the shape space and the structure of the dissipation tensor. The mass yields are found to be relatively robust, suggesting that the simple random walk presents a useful calculational tool. Quantitatively refined results can be obtained by including physically plausible forms of the dissipation, which amounts to simulating the Brownian shape motion in an anisotropic medium.