New insight into α clustering of heavy nuclei via their α decay

Abstract

Based on the available experimental data of nuclear charge radii and neutron skin thickness, we have renewed the two-parameter Fermi (2pF) form of nucleon density distributions in heavy nuclei. Subsequently, we focus on the α clustering phenomenon of heavy nuclei in terms of the preformation probability of α cluster before its penetration in α decay. Through the experimental decay data, the α preformation factor Pα is extracted for a large range of nuclei above the N=126 shell, leading to the interesting recognition on the behavior of α cluster formation factor. It is found that the present α preformation factor varies more smoothly towards the large neutron–proton ratio, as compared to those from the previous evaluations. This may be explained by the fact that we have separately considered proton and neutron density distributions of related nuclei, while they are treated as the same form in our previous studies. Meanwhile, the presence of the Z=92 subshell is somewhat revealed by the picture of α formation factor in this study. Moreover, the similarity between the Pα value and the pairing gap is clearly demonstrated, indicating the crucial role of pairing correlation involved in the α decay process.