New magic nuclei and conditions of their formation

The systematic studies of the arrangement features of single-particle nucleon subshells in even-even 90,92,94,96Zr isotopes and behavior of some known “magicity parameters” in isotopes and isotones neighboring the 96Zr nucleus have led to the interpretation of 96Zr as a new doubly magic nucleus. Analysis of the structure of nucleon shells in the 96Zr nucleus revealed a feature, which consisted in that near the Fermi energy it had filled proton (π1f 5/2) and neutron (v2d 5/2) subshells with an identical and large total momentum j = 5/2, which was called the j-j coupling. Above the π1f 5/2 shell, there is another filled shell (π2p 1/2) with two j = 1/2 protons. Applied to other filled shells, this empirical rule allowed revealing several new nontraditional magic nuclei: 96Sr (Z = 38, N = 58), π1f 5/2, v2d 5/2, and v3s 1/2 subshells; 54Ca (Z = 20, N = 34), π2p 3/2, v1d 3/2, and v2p 1/2 subshells; a pair of 30Si (Z = 14, N = 16) and 30S (Z = 16, N = 14) nuclei, π1d 5/2, v1d 5/2, and (π/v)2s 1/2 subshells; and a pair of 14C (Z = 6, N = 8) and 14O (Z = 8, N = 6) nuclei, 1p 3/2, v1p 3/2, and v2p 1/2 subshells. The existence of the magic nuclei 52,54Ca is widely discussed in the literature, the possibility of the existence of the other nuclei found is confirmed by the systematics of the behavior of the “magicity” parameters. The fact that shells with some nucleon numbers different from the classical magic numbers are closed may be due to the manifestation of a new type of interaction between nuclear protons and neutrons occupying certain subshells.