Nuclear isospin asymmetry in $\alpha$ decay of heavy nuclei

The effects of nuclear isospin asymmetry on $\alpha$-decay lifetimes of heavy nuclei are investigated within various phenomenological models of the nuclear potential for the $\alpha$ particle. We consider the widely used simple square-well potential and Woods-Saxon potential and modify them by including an isospin asymmetry term. We then suggest a model for the potential of the $\alpha$ particle motivated by a microscopic phenomenological approach of the Skyrme force model, which naturally introduces the isospin-dependent form of the nuclear potential for the $\alpha$ particle. The empirical $\alpha$-decay lifetime formula of Viola and Seaborg [J. Inorg. Nucl. Chem. 28, 741 (1966)] is also modified to include isospin asymmetry effects. The obtained $\alpha$-decay half-lives are in good agreement with the experimental data, and we find that including the nuclear isospin effects somehow improves the theoretical results for $\alpha$-decay half-lives. The implications of these results are discussed, and the predictions on the $\alpha$-decay lifetimes of superheavy elements are also presented.

Figure 1

The $\alpha$-particle nuclear potential in the nucleus ${}_{118}^{294}\mathrm{Uuo}$ of the three models considered in the present paper.

Figure 2

Half-lives of superheavy elements listed in Table 12. The horizontal axis denotes the atomic mass number, and the vertical axis represents the half-life in units of seconds.