Collinear cluster tripartition as sequential binary fission in the $^{235}$U(n$_{\rm th}$,f) reaction

TL;DR

This paper models collinear cluster tripartition in uranium-235 fission as a sequential binary process, explaining observed product yields through a dinuclear system framework and shell-corrected driving potentials.

Contribution

It introduces a theoretical model based on dinuclear systems and shell corrections to explain collinear tripartition in uranium-235 fission, aligning calculations with experimental data.

Findings

Sequential fission involves isotopes $^{82}$Ge and $^{154}$Nd.

The model predicts formation of Ni and Ge in the second fission stage.

Calculated yields match observed isotope $^{68}$Ni production.

Abstract

The mechanism leading to the formation of the observed products of the collinear cluster tripartition is carried out within the framework of the model based on the dinuclear system concept. The yield of fission products is calculated using the statistical model based on the driving potentials for the fissionable system. The minima of potential energy of the decaying system correspond to the charge numbers of the products which are produced with large probabilities in the sequential fission (partial case of the collinear cluster tripartition) of the compound nucleus. The realization of this mechanism supposes the asymmetric fission channel as the first stage of sequential mechanism. It is shown that only the use of the driving potential calculated by the binding energies with the shell correction allows us to explain the yield of the true ternary fission products. The theoretical model is applied to research collinear cluster tripartition in the reaction $^{235}$U(n$_{\rm th}$,f). Calculations showed that in the first stage of this fission reaction, the isotopes $^{82}$Ge and $^{154}$Nd are formed with relatively large probabilities and in the second stage of sequential fission of the isotope Nd mainly Ni and Ge are formed. This is in agreement with the yield of the isotope $^{68}$Ni which is observed as the product of the collinear cluster tripartition in the experiment.