New behaviors of α-particle preformation factors near doubly magic 100Sn * *Supported by the National Natural Science Foundation of China (12175170, 11675066, 12005303)

Abstract

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