Evidence of a near-threshold resonance in $^{11}$B relevant to the $\beta$-delayed proton emission of $^{11}$Be

TL;DR

This paper reports the direct observation of a narrow near-threshold resonance in $^{11}$B, confirming its role in the $eta$-delayed proton emission of $^{11}$Be and highlighting the behavior of weakly bound nuclei near the continuum.

Contribution

The study provides the first direct measurement of a near-threshold resonance in $^{11}$B, validating previous indirect inferences and advancing understanding of exotic decay modes in weakly bound nuclei.

Findings

Observation of a 11.4 MeV resonance in $^{11}$B

Resonance has J$^{}$ = 1/2$^{+}$ and $\

Resonance exhibits a sizable partial decay width for proton and $\

Abstract

A narrow near-threshold proton-emitting resonance (Ex = 11.4 MeV, J$^{\pi}$ = 1/2$^{+}$ and $\Gamma_{p}$ = 4.4 keV) was directly observed in $^{11}$B via proton resonance scattering. This resonance was previously inferred in the $\beta$-delayed proton emission of the neutron halo nucleus $^{11}$Be. The good agreement between both experimental results serves as a ground to confirm the existence of such exotic decay and the particular behavior of weakly bound nuclei coupled to the continuum. $R$-matrix analysis shows a sizable partial decay width for both, proton and $\alpha$ emission channels.