Sensitivity of one-neutron knockout of halo nuclei to their nuclear structure

TL;DR

This paper investigates how the parallel-momentum distribution of core fragments in one-neutron knockout reactions reveals detailed nuclear-structure information of halo nuclei, especially their wavefunction tails and excited states.

Contribution

It demonstrates that parallel-momentum distributions are sensitive to the ground-state wavefunction and excited states but insensitive to continuum resonances, aiding precise ANC extraction.

Findings

Distributions are sensitive to the tail of the ground-state wavefunction.

Presence of excited states reduces breakup strength, transferring flux to inelastic channels.

Resonances in the continuum do not affect the momentum distributions.

Abstract

Halo nuclei are located far from stability and exhibit a very peculiar structure. Due to their very short lifetime, they are often studied through reactions. Breakup reactions are of particular interest since their cross sections are large for these loosely-bound nuclei. Inclusive measurements of breakup--also called knockout reactions--have even higher statistics. In this proceeding, we study which nuclear-structure information can be inferred from the parallel-momentum distribution of the core of one-neutron halo nuclei after the knockout of its halo neutron. In particular, we analyse the influence of the ground-state wavefunction, the presence of excited states within the halo-nucleus spectrum and resonances in the core-neutron continuum. Our analysis shows that such observables are sensitive to the tail of the ground-state wavefunction. The presence of excited state decreases the breakup strength, and this flux is transferred to the inelastic-scattering channel. This indicates a conservation of the flux within each partial wave. We also show that the parallel-momentum distributions are insensitive to the existence of resonances within the continuum, they can thus be ignored in practice. This independence on the continuum argues that the parallel-momentum distributions are ideal observables to extract very precisely the ANCs of halo nuclei.