Effects of finite-range exchange terms and deformation on the α-decay half-lives using the B3Y NN interaction

An extensive study on the barrier properties and alpha-decay half-lives of nuclei within the mass range 89 <= Z 102 is conducted using the effective Botswana-3-Yukawa (B3Y) NN interaction, incorporating finite- and zero-range exchange forces. A key novelty of this work is the systematic analysis of nuclear deformation and exchange effects on half-lives along the isotopic chains. Particularly, for the finite- and zero-range exchange terms, this study investigates the appropriate strength of the Weizs & auml;cker term, Cs, which represents the surface contribution to the kinetic energy density. The penetration probability of the ground-state to ground-state alpha transitions is determined using the semiclassical Wentzel-Kramers-Brillouin (WKB) approximation by considering the Bohr-Sommerfeld quantization condition. The cluster formation model (CFM) is adopted to calculate the preformation probability S alpha. The driving potential reveals a cold valley at the canonical magic number ND = 126, affirming its shell closure property, while deformed subshell closures at N = 142 and N = 152 are also identified. These results align with predictions from Nilsson single-particle energies. A key finding of this study is that the inclusion of nuclear deformation significantly improves the accuracy of the calculated alpha-decay half-lives. The analysis also shows that the term Cs directly influences the nuclear surface energy, which in turn affects the potential barrier relevant to alpha decay. Specifically, a larger value of Cs = 41 increases the potential barrier, leading to longer half-lives, while a smaller value of Cs = 136 reduces the barrier, resulting in shorter half-lives. Importantly, for nuclei with Z 96, calculations involving finite-range exchange terms at Cs = 1 yield the smallest root mean square error (RMSE), suggesting a better agreement with experimental data, and indicating its prospect for the study of superheavy nuclei.