Understanding Nuclei in the upper sd - shell

TL;DR

This paper investigates the structure of nuclei in the upper sd-shell, combining gamma spectroscopy experiments with shell model calculations to explore the coexistence of single particle and collective behaviors.

Contribution

It provides new experimental data and theoretical analysis on high spin states and deformation phenomena in nuclei near A≈40 in the sd-shell region.

Findings

Observation of high spin states in sd-shell nuclei

Evidence of multiparticle, multihole rotational states

Indications of large deformation in certain states

Abstract

Nuclei in the upper-$sd$ shell usually exhibit characteristics of spherical single particle excitations. In the recent years, employment of sophisticated techniques of gamma spectroscopy has led to observation of high spin states of several nuclei near A$\simeq$ 40. In a few of them multiparticle, multihole rotational states coexist with states of single particle nature. We have studied a few nuclei in this mass region experimentally, using various campaigns of the Indian National Gamma Array setup. We have compared and combined our empirical observations with the large-scale shell model results to interpret the structure of these nuclei. Indication of population of states of large deformation has been found in our data. This gives us an opportunity to investigate the interplay of single particle and collective degrees of freedom in this mass region.