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Direct measurement of low-energy $^{22}$Ne(p,$\gamma$)$^{23}$Na resonances

机译：直接测量低能量$ ^ {22} $ Ne（p，$ \ gamma $）$ ^ {23} $ Na   共振

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The $^{22}$Ne(p,$\gamma$)$^{23}$Na reaction is the most uncertain process inthe neon-sodium cycle of hydrogen burning. At temperatures relevant fornucleosynthesis in asymptotic giant branch stars and classical novae, itsuncertainty is mainly due to a large number of predicted but hithertounobserved resonances at low energy. Purpose: A new direct study of low energy$^{22}$Ne(p,$\gamma$)$^{23}$Na resonances has been performed at the Laboratoryfor Underground Nuclear Astrophysics (LUNA), in the Gran Sasso NationalLaboratory, Italy. Method: The proton capture on $^{22}$Ne was investigated indirect kinematics, delivering an intense proton beam to a $^{22}$Ne gas target.$\gamma$ rays were detected with two high-purity germanium detectors enclosedin a copper and lead shielding suppressing environmental radioactivity.Results: Three resonances at 156.2 keV ($\omega\gamma$ =(1.48\,$\pm$\,0.10)\,$\cdot$\,10$^{-7}$ eV), 189.5 keV ($\omega\gamma$ =(1.87\,$\pm$\,0.06)\,$\cdot$\,10$^{-6}$ eV) and 259.7 keV ($\omega\gamma$ =(6.89\,$\pm$\,0.16)\,$\cdot$\,10$^{-6}$ eV) proton beam energy, respectively,have been observed for the first time. For the levels at 8943.5, 8975.3, and9042.4 keV excitation energy corresponding to the new resonances, the$\gamma$-decay branching ratios have been precisely measured. Three additional,tentative resonances at 71, 105 and 215 keV proton beam energy, respectively,were not observed here. For the strengths of these resonances, experimentalupper limits have been derived that are significantly more stringent than theupper limits reported in the literature. Conclusions: Based on the presentexperimental data and also previous literature data, an updated thermonuclearreaction rate is provided in tabular and parametric form. The new reaction rateis significantly higher than previous evaluations at temperatures of 0.08-0.3GK.
机译：$ ^ {22} $ Ne（p，$ \ gamma $）$ ^ {23} $ Na反应是氢燃烧的氖-钠循环中最不确定的过程。在渐近巨型分支星和经典新星中与核合成有关的温度下，其不确定性主要是由于在低能量下有大量预测但迄今未观察到的共振。目的：在格兰萨索国家实验室的地下核天体物理实验室（LUNA）进行了新的直接研究，研究了低能$ ^ {22} $ Ne（p，$ \ gamma $）$ ^ {23} $ Na共振。 ， 意大利。方法：间接运动学研究了在$ ^ {22} $ Ne上的质子俘获，将强烈的质子束传递到$ ^ {22} $ Ne气体靶上。用两个高纯度锗探测器探测到了\\γ射线结果：156.2 keV处的三个共振（$ \ omega \ gamma $ =（1.48 \，$ \ pm $ \，0.10）\，$ \ cdot $ \，10 $ ^ {-7 } $ eV），189.5 keV（$ \ omega \ gamma $ =（1.87 \，$ \ pm $ \，0.06）\，$ \ cdot $ \，10 $ ^ {-6} $ eV）和259.7 keV（$第一次分别观察到\ omega \ gamma $ =（6.89 \，$ \ pm $ \，0.16）\，$ \ cdot $ \，10 $ ^ {-6} $ eV）质子束能量。对于与新共振相对应的8943.5、8975.3和9042.4 keV激发能级，已精确测量了γ\-γ衰变分支比。在这里没有观察到分别在71、105和215 keV质子束能量下的三个附加的共振。对于这些共振的强度，已经得出了实验上限值，其比文献中报道的上限值严格得多。结论：基于目前的实验数据和以前的文献数据，以表格和参数形式提供了更新的热核反应速率。在0.08-0.3GK的温度下，新的反应速率明显高于以前的评估。

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