Theoretical investigation on double- α decay from radioactive nuclei

Abstract

Theoretical investigation on the concept of double-\ensuremath{\alpha} (2\ensuremath{\alpha}) decay is studied in the framework of the modified generalized liquid drop model with different preformation parameters. Comparison of 2\ensuremath{\alpha} and $^{8}\mathrm{Be}$ emission from various nuclei reveals that 2\ensuremath{\alpha} emission is more probable than $^{8}\mathrm{Be}$ emission, and $^{8}\mathrm{Be}$ emission does not occur due to its highly unstable nature. Probable 2\ensuremath{\alpha} emitters are investigated for nuclei in the natural isotopic compositions of elements with atomic numbers varying from 60 to 92 and our predictions on half-lives are in agreement with the values reported by Tretyak [Nucl. Phys. At. Energy. 22, 121 (2021)] using the semiempirical formula for cluster decays. The computed 2\ensuremath{\alpha} half-life of $^{209}\mathrm{Bi}$ using the SemFIS formula is found to be $1.926\ifmmode\times\else\texttimes\fi{}{10}^{15}\phantom{\rule{0.16em}{0ex}}\mathrm{yr}$ and is compared with the first reported experimental limit $({T}_{1/2}>2.9\ifmmode\times\else\texttimes\fi{}{10}^{20}\phantom{\rule{0.16em}{0ex}}\mathrm{yr})$ estimated from the experimental data of de Marcillac et al. [Nature (London) 422, 876 (2003)]; and this observation demonstrates the possibility of the detection of 2\ensuremath{\alpha} decay from the $^{209}\mathrm{Bi}$ isotope. We have also predicted 2\ensuremath{\alpha} half-lives for various isotopes $^{191\text{--}226}\mathrm{At}$, $^{193\text{--}228}\mathrm{Rn}$, $^{197\text{--}232}\mathrm{Fr}$, $^{201\text{--}235}\mathrm{Ra}$, $^{205\text{--}237}\mathrm{Ac}$, Th, $^{212\text{--}241}\mathrm{Pa}$, $^{215\text{--}243}\mathrm{U}$, and $^{219\text{--}245}\mathrm{Np}$, and most of the decay half-lives are below the measurable upper limit thereby promising chances to enhance experimental investigations on 2\ensuremath{\alpha} decay in the future.