Neutron-hole states in 45Ar from p(46Ar,d)45Ar reactions

TL;DR

This study measures neutron hole states in the neutron-rich 45Ar nucleus using transfer reactions, confirming spin assignments and highlighting discrepancies between experimental results and shell model predictions.

Contribution

It provides new experimental data on neutron hole states in 45Ar and compares these with shell model predictions, revealing limitations of current models.

Findings

Confirmed spin assignments for four low-lying states.

Shell model accurately predicts ground and p3/2 states.

Shell model fails for s1/2 and d3/2 hole-states.

Abstract

To improve the effective interactions in the pf shell, it is important to measure the single particle- and hole- states near the N=28 shell gap. In this paper, the neutron spectroscopic factors of hole-states from the unstable neutron-rich 45Ar (Z=18, N=27) nucleus have been studied using 1H(46Ar, 2H)45Ar transfer reaction in inverse kinematics. Comparison of our results with the particle-states of 45Ar produced in 2H(44Ar, H)45Ar reaction shows that the two reactions populate states with different angular momentum. Using the angular distributions, we are able to confirm the spin assignments of four low-lying states of 45Ar. These are the ground state (f7/2), the first-excited (p3/2), the s1/2 and the d3/2 states. While large basis shell model predictions describe spectroscopic properties of the ground and p3/2 states very well, they fail to describe the s1/2 and d3/2 hole-states.