Connection of four-dimensional Langevin model and Hauser-Feshbach theory to describe statistical decay of fission fragments

TL;DR

This paper presents a combined modeling approach using a four-dimensional Langevin model and Hauser-Feshbach theory to improve predictions of fission fragment yields, TKE, and prompt neutron observables across various Pu isotopes.

Contribution

The study introduces a novel superposition method of two fission modes within a Langevin framework, integrated with Hauser-Feshbach decay, to enhance the accuracy of fission observable predictions.

Findings

Qualitatively reproduces known fission trends.

Quantitative discrepancies remain with experimental data.

Approach shows potential for predicting difficult-to-measure nuclides.

Abstract

We developed a method superposing two different fission modes calculated in a four-dimensional Langevin model to obtain more accurate fission fragment yield and total kinetic energy (TKE). The two fission modes correspond to the standard I and standard II modes reported by Brosa et al., and parameters in the Langevin model and the superposing ratio were determined to reproduce the fission fragment yield of $^{240}$Pu of spontaneous fission. We also investigated the fission fragment yields and the TKEs of other Pu isotopes by using the same Langevin parameters and different superposing ratios, such as spontaneous fission of $^{238,242}$Pu and neutron-induced fission of $^{239}$Pu. The prompt fission observables, such as the neutron multiplicity, the prompt fission neutron spectrum, and the independent fission product yield were calculated in the Hauser-Feshbach statistical decay model implemented in a nuclear reaction code TALYS with $^{239}$Pu(n,f) in the incident energies ranging from thermal energy up to 5 MeV. The calculated fission observables qualitatively reproduce several known trends while calculated results have quantitative discrepancies between reported data. Although more improvements are needed for the most important nuclides, it turned out that our approach has the capability to provide prompt fission observables for difficult-to-measure nuclides.