The Nuclear Shell Model Toward the Drip Lines

TL;DR

This paper explores the phenomenon of islands of inversion near neutron drip lines, explaining the configuration inversions and shape transitions using the Interacting Shell Model in large valence spaces, highlighting their unified nature.

Contribution

It provides a unified explanation of the islands of inversion around N=20 and N=28 as a single phenomenon in magnesium isotopes, using large-scale shell model calculations.

Findings

Identification of the islands of inversion near N=20 and N=28.

Unified description of these islands as a single phenomenon.

Explanation of shape transitions due to competing nuclear forces.

Abstract

We describe the "islands of inversion" that occur when approaching the neutron drip line around the magic numbers N=20, N=28 and N=40 in the framework of the Interacting Shell Model in very large valence spaces. We explain these configuration inversions (and the associated shape transitions) as the result of the competition between the spherical mean field (monopole) which favors magicity and the correlations (multipole) which favor deformed intruder states. We also show that the N=20 and N=28 islands are in reallity a single one, which for the Magnesium isotopes is limited by N=18 and N=32.