Neutron occupancies and single-particle energies across the stable tin isotopes

TL;DR

This study measures neutron occupancies and energies in stable tin isotopes, revealing near-degeneracies and energy spacings that inform nuclear structure understanding.

Contribution

It provides new experimental data on neutron occupancies and single-particle energies across tin isotopes, enhancing nuclear shell model insights.

Findings

Two orbitals are nearly degenerate below N=64.

Remaining three orbitals are also degenerate and about two MeV less bound.

Data compare favorably with previous systematic studies.

Abstract

The occupancies and vacancies of the valence neutron orbitals across the stable tin isotopic chain from $112\leq A\leq 124$ have been determined. These were inferred from the cross sections of neutron-adding and -removing reactions. In each case, the reactions were chosen to have good angular-momentum matching for transfer to the low- and high-$\ell$ orbitals present in this valence space. These new data are compared to older systematic studies. The effective single-neutron energies are determined by combining information from energy centroids determined from the adding and removing reactions. Two of the five orbitals are nearly degenerate, below $N=64$, and approximately two MeV more bound than the other three, which are also degenerate.