Structure of A=138 isobars above the 132Sn core and the N-N interaction in the neutron-rich environment

TL;DR

This study employs large-scale shell model calculations with realistic and empirical interactions to analyze the structure and collectivity of neutron-rich A=138 nuclei above 132Sn, providing insights into nuclear interactions in exotic environments.

Contribution

First comprehensive shell model analysis of A=138 isobars using untruncated calculations with realistic and empirical Hamiltonians, highlighting the importance of local interactions.

Findings

Reproduces vibrational states in 138Te and 138Xe accurately.

Shows the significance of untruncated shell model calculations.

Highlights differences in two-body matrix elements between interactions.

Abstract

Large basis untruncated shell model calculations have been done for the A=138 neutron -rich nuclei in the pi(gdsh) X nu(hfpi) valence space above the 132Sn core. Two (1+2) -body nuclear Hamiltonians, viz., realistic CWG and empirical SMPN in this model space have been used. Calculated ground state binding energies, level spectra and other spectroscopic properties have been compared with the available experimental data. Importance of untruncated shell model calculations in this model space has been pointed out. Shell model results for the very neutron rich Sn isotope (138Sn, N/Z=1.76) of astrophysical interest for which no spectroscopic information except beta -decay half life is available, have been presented. Shell structure and evolution of collectivity in the even-even A=138 isobars have been studied as a function of valence neutron and /or proton numbers. Calculations done for the first time, reproduce remarkably well the collective vibrational states in 138Te and 138Xe. Comparison of some of the important two-body matrix elements of the empirical SMPN, CW5082 and the realistic CWG interactions has been done. These matrix elements are important for ground state binding energies and low-lying spectra of nuclei in this region. Consideration of the predictability of the two interactions seems to suggest that, in order to incorporate the special features of the N-N interaction in such exotic n-rich environment above the 132Sn core, the use of local spectroscopic information from the region might be essential.