Double-magicity of proton drip-line nucleus 22Si with ab initio calculation

New magic numbers have been discovered in the neutron-rich region of the nuclear chart. However, there has been a lack of research on proton-rich nuclei. O-22, the mirror nucleus of Si-22, is a double-magic nucleus bearing a high E(2(1)(+) ). Whether 22Si exhibits double-magic characters is an intriguing topic. To investigate this matter, we utilized ab initio valence space in-medium similarity renormalization group for Si-22/O-22, and their nearby nuclei. Our ab initio calculations provide good descriptions for the double magicity of O-22, as well as the shell evolution of N = 14 and Z = 14 through E(2(1)(+) ). The computed E(2(1)(+) ) indicate that the closure of Z = 14 sub-shell in proton-rich nuclei is weaker than the N = 14 sub-shell closure in their mirror nuclei. Particularly, the calculated E(2(1)(+) ) of Si-22 is 800 keV lower than the one of O-22. To further explore the magicity of Si-22, the mirror energy difference (MED) of Si-26/Mg-26, Si-24/Ne-24, as well as( 22)Si/O-22 are calculated. The results demonstrate that the calculated MEDs agree well with available experimental data, and the E(2(1)(+) ) values of Si-22,Si-24,Si-26 are all lower than their respective mirror nuclei due to the Thomas-Ehrman shift with large s1/2 occupation. Moreover, our calculation provides that the many-body configurations of the low-lying state of( 22)Si/O-22 are nearly identical despite the fact that the states bearing large MED. In conclusion, our ab initio results suggest that Si-22 is a double magic nucleus, similar to its mirror nucleus O-22, albeit with a lower E(2(1 )(+)).(c) 2023 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons .org /licenses /by /4 .0/). Funded by SCOAP(3).