The decay of the elusive narrow, near-threshold proton resonance in B was investigated at Laboratori Nazionali di Legnaro (INFN) in a particle- coincidence experiment, using the Li(Li,p) fusion-evaporation reaction and the GALILEO-GALTRACE setup. No clear signature was found for a possible E1 decay to the 1/2, first-excited state of B, predicted by the Shell Model Embedded in the Continuum (SMEC) with a branching of with respect to the dominant particle-decaying modes. The statistical analysis of the -ray spectrum provided an average upper limit of for this -ray branching, with a global significance of 5. On the other hand, by imposing a global confidence level of 3, a significant excess of counts was observed for E keV, corresponding to a resonance energy of 11429(20) keV (namely 200(20) keV above the proton separation energy of B) and a -ray branching of . This result is compatible with the SMEC calculations, potentially supporting the existence of a near-threshold proton resonance in B.

中文翻译：

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寻找 11B 中窄近阈值质子共振的 γ 衰变


莱尼亚罗国家实验室 (INFN) 使用 Li(Li,p) 聚变蒸发反应和 GALILEO-GALTRACE 装置，在粒子符合实验中研究了 B 中难以捉摸的窄近阈值质子共振的衰变。没有发现可能的 E1 衰变到 B 的 1/2 第一激发态的明显特征，这是由嵌入连续体的壳模型 (SMEC) 预测的，其分支相对于主要粒子衰变模式。 γ 射线谱的统计分析提供了该 γ 射线分支的平均上限，其全局显着性为 5。另一方面，通过施加全局置信水平 3，观察到 E 的计数显着过量。 keV，对应于 11429(20) keV 的共振能量（即比 B 的质子分离能高 200(20) keV）和 的 射线分支。该结果与 SMEC 计算一致，可能支持 B 中存在近阈值质子共振。