Calculation of α preformation for nuclei near N=162 and N=184

The α preformation factor and the penetration probability are carefully analyzed for heavy and superheavy even-even nuclei. The penetration probability of an α cluster in the parent nucleus is calculated within the WKB approximation, whereas the nuclear potential between an α cluster and the daughter nucleus is obtained in the frame of a double-folding model with a density-dependent nucleon-nucleon interaction, in which the zero-range exchange term is supplemented. The α preformation factors in different shell regions are compared. It is shown that shell effects play an important role in α preformation. The preformation factor can supply information on the nuclear structure, and the penetration probability mainly determines the α-decay half-life. The results indicate that the deformed-subshell region at N=162 is different from that at N=152, and Z=114 and N=184 may lie in the closed-shell region.