Microscopic Calculation of Fission Product Yields with Particle Number Projection

TL;DR

This paper introduces a microscopic model combining collective fission dynamics with particle number projection to accurately predict fission fragment yields, including odd-even staggering, for uranium and plutonium isotopes.

Contribution

It develops a novel approach integrating particle number projection into fission modeling, enabling detailed isotopic yield predictions within nuclear density functional theory.

Findings

Particle number projection reproduces odd-even staggering in charge yields.

The model accurately predicts primary fission fragment distributions for $^{235}$U and $^{239}$Pu.

First realistic determination of two-dimensional isotopic yields within DFT.

Abstract

Fission fragments' charge and mass distribution is an important input to applications ranging from basic science to energy production or nuclear non-proliferation. In simulations of nucleosynthesis or calculations of superheavy elements, these quantities must be computed from models, as they are needed in nuclei where no experimental information is available. Until now, standard techniques to estimate these distributions were not capable of accounting for fine-structure effects, such as the odd-even staggering of the charge distributions. In this work, we combine a fully-microscopic collective model of fission dynamics with a recent extension of the particle number projection formalism to provide the highest-fidelity prediction of the primary fission fragment distributions for the neutron-induced fission of $^{235}$U and $^{239}$Pu. We show that particle number projection is an essential ingredient to reproduce odd-even staggering in the charge yields and benchmark the performance of various empirical probability laws that could simulate its effect. This new approach also enables for the first time the realistic determination of two-dimensional isotopic yields within nuclear density functional theory.