Updated systematics of intermediate-energy single-nucleon removal cross sections

Abstract

The body of experimental measurements of intermediate-energy reactions that remove a single nucleon from a secondary beam of neutron- or proton-rich nuclei continues to grow. These data have been analyzed consistently using an approximate, eikonal-model treatment of the reaction dynamics combined with appropriate shell-model descriptions of the projectile initial state, the bound final states spectrum of the reaction residue, and single-particle removal strengths computed from their wave-function overlaps. The systematics of the ratio ${R}_{s}$ of the measured inclusive cross section to all bound final states and the calculated cross section to bound shell-model states---in different regions of the nuclear chart and involving both very weakly bound and strongly bound valence nucleons---is important in relating the empirically deduced orbital occupancies to those from the best available shell-model predictions. Importantly, several new higher-energy measurements, for which the sudden-approximation aspect of the dynamical description is placed on an even stronger footing, now supplement the previously analyzed measurements. These additional data sets are discussed. Their ${R}_{s}$ values are shown to conform to and reinforce the earlier-observed systematics, with no indication that the approximately linear reduction in ${R}_{s}$ with increasing nucleon separation energy is a consequence of a breakdown of the sudden approximation.