Cross sections of removal reactions populating weakly-bound residual nuclei

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.