Systematic study of unfavored α-decay half-lives of closed-shell nuclei related to ground and isomeric states

摘要

In the present work, the unfavored α-decay half-lives and α preformation probabilities of closed-shell nuclei related to ground and isomeric states around Z = 82, N = 82 and 126 shell closures are investigated by adopting the two-potential approach from the perspective of valence nucleon (hole) and isospin asymmetry of the parent nucleus. The results indicate that α preformation probability has linear dependence on N_pN_n or N_pN_nI, the same as the case of favored α decay in our previous work [X.-D. Sun et al., Phys. Rev. C 94, 024338 (2016)]. N_p, N_n, and I represent the number of valence protons (holes), the number of valence neutrons (holes), and the isospin of the parent nucleus, respectively. Fitting the α preformation probability data extracted from the differences between experimental data and calculated half-lives without a shell correction, we give two linear formulas of the α preformation probabilities and the values of corresponding parameters. Based on the formulas and corresponding parameters, we calculate the α-decay half-lives for those nuclei. The calculated results can well reproduce the experimental data.