Investigation of Continuum States in the Unbound Neutron-Rich N=7 & 9 Isotones via Breakup and Knockout

TL;DR

This study investigates unbound neutron-rich N=7 and 9 isotones using breakup and knockout reactions, revealing virtual s-wave strength and narrow resonances, clarifying the structure of these exotic nuclei.

Contribution

It provides new experimental insights into the continuum states of unbound N=7 and 9 isotones, challenging previous interpretations of 13Be's structure.

Findings

Virtual s-wave strength observed near threshold in N=7 isotones.

Narrow resonance identified at threshold in 12Be+n spectrum.

Disproves earlier reports of a strong virtual s-wave state in 13Be.

Abstract

The structure of the unbound nuclei 9He, 10Li and 13Be has been explored using breakup and proton-knockout from intermediate energy 11Be and 14,15B beams. In the case of both N=7 isotones, virtual s-wave strength is observed near threshold together with a higher-lying resonance. A very narrow structure at threshold in the 12Be+n relative energy spectrum is demonstrated to arise from the decay of the 14Be*(2+), discounting earlier reports of a strong virtual s-wave state in 13Be.