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

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 alpha clustering phenomenon of heavy nuclei in terms of the preformation probability of alpha cluster before its penetration in alpha decay. Through the experimental decay data, the alpha preformation factor P-alpha is extracted for a large range of nuclei above the N = 126 shell, leading to the interesting recognition on the behavior of alpha cluster formation factor. It is found that the present alpha 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 some what revealed by the picture of alpha formation factor in this study. Moreover, the similarity between the P-alpha value and the pairing gap is clearly demonstrated, indicating the crucial role of pairing correlation involved in the alpha decay process. (c) 2017 The Authors. Published by Elsevier B.V.