Isotopic dependence of $(n,\alpha)$ reaction cross sections for Fe and Sn nuclei

TL;DR

This study investigates how $(n,lpha)$ reaction cross sections vary across Fe and Sn isotopes, revealing their dependence on neutron number and implications for astrophysics and nuclear applications.

Contribution

It provides a systematic analysis of $(n,lpha)$ reactions in Fe and Sn isotopes using Hauser-Feshbach model calculations, highlighting isospin effects and reaction trends.

Findings

Cross sections peak at low-mass isotopes and decrease for neutron-rich nuclei.

Reaction $Q$-values influence the evolution of cross sections.

$(n,lpha)$ reactions are significant for low-mass isotopes in stellar environments.

Abstract

The $(n,\alpha)$ reactions play an important role for the energy generation and the synthesis of chemical elements in the stars, as well as for nuclear engineering and medical applications. The aim of this study is to explore the evolution of $(n,\alpha)$ reactions in Fe and Sn isotope chains in order to assess their properties with the increase of neutrons in target nucleus, and compare with other relevant neutron induced reactions. Model calculations of the cross sections are based on the statistical Hauser-Feshbach model in TALYS implementation, using global optical model potential that is additionally adjusted by the $(n,\alpha)$ cross section data for $^{54}$Fe and $^{118}$Sn. The calculations of $(n,\alpha)$ reactions in Fe and Sn isotopes provide the insight into their isospin dependence and properties over the complete relevant range of neutron energies. The results show the evolution of the cross sections with pronounced maxima at low-mass isotopes, and rather strong decrease for neutron-rich nuclei consistent with the reduction of the reaction $Q$-value and increased contributions from other exit channels from compound nucleus. The analysis of the Maxwellian averaged cross sections at temperatures in stellar environment shows that while the $(n,\alpha)$ reactions contribute for the low-mass isotopes, in neutron induced reactions with nuclei with neutron excess, $\gamma$ and neutron emission dominate.