High energy states in the self-conjugate 16O nucleus were investigated by analyzing 13C(3He,α)12C reactions in the bombarding energy range 1.4–2.2 MeV. Thanks to a low-threshold and high-resolution array, we succeed in measuring cross sections of the decay channel where an α particle is emitted in coincidence with a 12C nucleus in the Hoyle state, leading to 4α particles in the final channel. The analysis of angular distributions indicates the occurrence of two low-spin resonant states, respectively with Jπ=2+ and 3−, at energies of ≈ 24.1 and 24.5 MeV. In this energy window, the observed branching ratios for the transition involving the emission of the Hoyle state are well larger than calculations based on barrier penetration, signaling the possible occurrence of high-energy states in 16O with a large cluster component.

中文翻译：

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在低能下通过 3He+13C 反应探测 16O 的高能激发态聚集


通过分析 1.4–2.2 MeV 轰击能量范围内的 13C（3He，α）12C 反应，研究了自共轭 16O 原子核中的高能态。得益于低阈值和高分辨率阵列，我们成功地测量了衰变通道的横截面，其中 α 粒子与霍伊尔态的 12C 原子核同时发射，导致最终通道中有 4α 粒子。角度分布分析表明，在能量为 ≈ 24.1 和 24.5 MeV 时，会出现两种低自旋谐振态，分别为 Jπ=2+ 和 3-。在这个能量窗口中，观察到的涉及 Hoyle 态发射的跃迁的分支比远大于基于势垒穿透的计算，这表明在 16O 中可能出现具有大簇分量的高能态。