Quadrupole dominance in light Cd and Sn isotopes

TL;DR

This paper uses shell model calculations to analyze quadrupole and pairing effects in light Cd and Sn isotopes, revealing the persistence of quadrupole dominance and the influence of pairing forces across different neutron numbers.

Contribution

It demonstrates the effectiveness of shell model calculations with a single free parameter in describing electromagnetic rates and clarifies the evolution of quadrupole dominance versus seniority in these isotopes.

Findings

Weak permanent deformation in Cd isotopes supports pseudo SU3 symmetry.

Quadrupole dominance persists in light Cd isotopes for N ≤ 64.

Seniorities dominate in Sn isotopes for N ≥ 64.

Abstract

Shell model calculations with the neutron effective charge as single free parameter describe well the \bet and \bef rates for $N\le 64$ in the Cd and Sn isotopes. The former exhibit weak permanent deformation corroborating the prediction of a pseudo SU3 symmetry, which remains of heuristic value in the latter, though the pairing force erodes the quadrupole dominance. Calculations in $10^7$ and $10^{10}$-dimensional spaces exhibit almost identical patterns: A vindication of the shell model. For $N\ge 64$ quadrupole dominance is accentuated in the Cd isotopes and gives way to seniority dominance for the Sn isotopes.