Alpha emission from fast neutron interactions with ⁶⁴Zn nuclei

Abstract

In this study, the nuclear process 64Zn(n, α)61Ni induced by fast neutrons in the 64Zn nucleus was investigated. With the authors' computer programs and Talys codes, cross-sections, angular correlations, and forward-backward asymmetry effects were investigated for incident neutrons with energies ranging from 0.5 MeV to 25 MeV. 61Ni cross-sections were determined through an investigation of nuclear reaction mechanisms (direct, compound, pre-equilibrium) and discrete and continuum states within the 61Ni residual nucleus. Our analysis of the neutron incident and alpha emergent channels included the extraction of optical potential parameters (with real and imaginary parts) with volume, surface, and spin-orbit components. The cross-sections calculated theoretically and found in our experiments confirm earlier published data. For neutrons with energies of a few MeV, the 64Zn(n, α)61Ni reaction produced by fast neutrons exhibits an unusual forward-backward asymmetry. At this energy, the observed effect cannot be explained by direct mechanisms with orders of magnitude lower; compound processes that predominate must be used. To understand the observed forward-backward asymmetry effect, the spectra of emitted alpha particles were modelled by the direct Monte Carlo method while taking into consideration the energy loss of alpha particles on Zn targets with finite dimensions.