A ferro-deformation at the open quantum system with protons, Z = 8, neutrons, N = 20: 28O

TL;DR

This paper proposes that nuclei with Z=8 and N=20, including 28O beyond the neutron drip line, exhibit ferro-deformation due to shape phase transitions driven by isospin-dependent interactions, revealing a pattern of large deformations in nuclear chart regions.

Contribution

It introduces the concept of ferro-deformation at N=20 for Z=8 nuclei, explaining shape transitions and their impact on nuclear stability, especially for 28O.

Findings

Ferro-deformation occurs at N=20 for Z=8 nuclei.

Large deformation at N=18 may cause 26O to be unbound.

Pattern of critical points aligns with specific (Z, N) coordinates.

Abstract

We offer a possibility that the nuclear system with protons, Z = 8 has a large deformation at neutrons, N = 20; 28O that is beyond the neutron drip line. According to our previous works [arXiv: 1604.05013, 1604.02786, 1604.01017], it is expected that the ferro-deformation would occur at Z = 8, N = 20 through a shape phase transition at N = 18 out of N =16. The shape transition can be explained in terms of isospin dependent spin-orbital interactions between neutrons in the d3/2 orbital and protons in the d5/2 orbital, by yielding both the neutron and the proton pseudo-shell configurations built on each combined subshells. We argue that such a large deformation at N = 18 would be responsible for the 26O to be unbound, leading to a ground state neutron emitter. The ferro-deformation is mapped on the nuclear chart such that is around the following critical proton, neutron coordinates, (Z, N); (64, 104), (40, 64), (20, 40), (8, 20). This configuration depicts a beautiful pattern coming from a harmonious order in the microscopic quantum world.