Cross sections of removal reactions populating weakly-bound residual nuclei

TL;DR

This paper investigates the impact of weak residue binding on single nucleon removal reaction cross sections, finding that explicit residue break-up modeling is often unnecessary for accurate calculations.

Contribution

It demonstrates that neglecting residue dissociation effects yields similar results to including them, simplifying reaction modeling for weakly-bound nuclei.

Findings

Residue break-up effects have minimal impact on cross sections.

Consistent residue structure and density are key for accurate modeling.

Explicit dissociation treatment can often be omitted without loss of accuracy.

Abstract

In many instances, single nucleon removal reactions from neutron-proton asymmetric projectile nuclei populate final states in the residual nuclei that are very weakly bound. Familiar examples include neutron removal reactions from neutron-rich $^{11}$Be and $^{12}$Be, the latter populating the well-known $1/2^+$ halo ground-state and $1/2^-$ excited-state of $^{11}$Be - both states less than 1 MeV from the first neutron-decay threshold. Numerous additional examples arise in reactions of asymmetric $p$- and $sd$-shell nuclei. The importance of this weak residue binding upon calculated single-nucleon removal reaction cross sections is quantified by means of model calculations that neglect or include the dissociation degree of freedom of the residual nuclei. The calculated removal-reaction cross sections for two representative $p$-shell projectiles indicate that an explicit treatment of these residue break-up effects is unnecessary and that the differences between the break-up and no break-up calculations are small provided a consistent description of the residue structure and density is used.