About a decade ago, the measurement of the decay products of 11Be yielded an unexpectedly large abundance of 10Be. The presence of 10Be daughters was interpreted as a signature of the novel \uD835\uDEFD ⁸́₂ -delayed proton emission. An alternative hypothesis soon followed, that free neutrons and loosely-bound neutrons in atomic nuclei may decay into unseen dark particles. This alternative hypothesis could explain the abundance of 10Be daughters and the long-standing neutron lifetime puzzle. Such a hypothesis has impacts on the stability of neutron stars, elemental abundances from Big Bang nucleosynthesis, and physics beyond the Standard Model. In low-energy nuclear physics specifically, the new hypothesis brought a sharp focus to the behavior of nuclear systems near particle-emission thresholds and the mechanism of \uD835\uDEFD ⁸́₂ -delayed proton emission.More recently, a number of experiments have been conducted with beams of short-lived 11Be (13.8 s) and long-lived 10Be (1.5 MYr) to measure directly the \uD835\uDEFD ⁸́₂ -delayed proton and \uD835\uDEFD ⁸́₂ -delayed \uD835\uDEFC decays of 11Be and related structure in 11B. Similarly, many new theoretical calculations have made pre- and post-dictions on the energies and intensities of these decay channels in 11Be. Most theoretical model calculations predict \uD835\uDEFD ⁸́₂ -delayed proton branching ratios smaller than reported by experiment. The branching ratio of the \uD835\uDEFD ⁸́₂ -delayed proton decay in 11Be remains an open question.At the National Superconducting Cyclotron Laboratory (NSCL), on the campus of Michigan State University, we used the Gaseous Detector with Germanium Tagging (GADGET) system to measure the \uD835\uDEFD ⁸́₂ -delayed charged particle decay of 11Be, in search of the \uD835\uDEFD ⁸́₂ -delayed proton decay. R-matrix calculations and Bayesian methods were employed to describe the competing (and far more frequent) \uD835\uDEFD ⁸́₂ -delayed \uD835\uDEFC channel. This dissertation covers the experimental and analysis methods used to produce the second reported measurement of the novel \uD835\uDEFD ⁸́₂ -delayed proton emission and early interpretation of this new result.
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