New behaviors ofα-particle preformation factors near doubly magic ^(100)Sn

Theα-particle preformation factors of nuclei above doubly magic nuclei ^(100)Sn and ^(208)Pb are investigated within the generalized liquid drop model.The results show that theα-particle preformation factors of nuclei near self-conjugate doubly magic ^(100)Sn are significantly larger than those of analogous nuclei just above ^(208)Pb,and they will be enhanced as the nuclei move towards the N=Z line.The proton-neutron correlation energy E_(p-n) and two protons-two neutrons correlation energy E_(2p-2n) of nuclei near ^(100)Sn also exhibit a similar situation,indicating that the interactions between protons and neutrons occupying similar single-particle orbitals could enhance theα-particle preformation factors and result in superallowed a decay.This also provides evidence of the significant role of the proton-neutron interaction onα-particle preformation.Also,the linear relationship betweenα-particle preformation factors and the product of valence protons and valence neutrons for nuclei around ^(208)Pb is broken in the100 Sn region because theα-particle preformation factor is enhanced when a nucleus near 100 Sn moves towards the N=Z line.Furthermore,the calculatedαdecay half-lives fit well with the experimental data,including the recent observed self-conjugate nuclei ^(104)Te and ^(108)Xe[Phys.Rev.Lett.121,182501(2018)].