Comment on "Direct Observation of Proton Emission in $^{11}$Be"

TL;DR

This paper critically examines a previous claim of proton emission in 11Be decay, arguing that the original conclusions are incorrect due to analysis errors and background misinterpretation.

Contribution

It provides a detailed critique of prior experimental results, identifying flaws and proposing alternative explanations for the observed data.

Findings

The original beta strength assignment was incorrect.

The observed spectral features can be explained by background effects.

The claimed resonance in 11Be is not supported by the reanalysis.

Abstract

We argue that conclusions of [PRL 123, 082501 (2019)] are incorrect. The authors present the direct observation of beta-delayed proton emission in the beta decay of 11Be. From the determined branching ratio for this process and from the energy spectrum of emitted protons the existence of a so far unobserved narrow resonance in 11Be was deduced. The given beta strength for the transition to this state is however wrong. In addition, we show that the combination of peak position and branching ratio is in strong disagreement with models considered by the authors. Furthermore, we identify several deficiencies in the analysis, and we provide possible sources of background, that could explain the error.