Alpha emission from fast neutron interactions with ⁶⁴Zn nuclei

¹ Romanian Scientific Research Agency, Bucharest (ANCS), County Department for Education Bihor, Mihai Eminescu 11, Oradea 410010, Bihor, Romania
² University of Bucharest, Faculty of Physics, Magurele 077125, Ilfov, Romania
³ European Center for Nuclear Research (CERN), 1211 Geneva 23, Switzerland
⁴ Institute for Space Sciences, 077124 Magurele, Romania

^* Corresponding author: coprea2007@yahoo.co.uk

Published online: 8 December 2023

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.