$\mathrm{^{75}As}(\mathrm{n},γ)\mathrm{^{76}As}$反应的测量：与$\mathrm{^{76}Ge}$的0$νββ$衰变搜索及天体物理$s$-过程温度相关

中文摘要 AI 辅助

$\rm^{75}As$(n,$\gamma$)$\rm^{76}As$反应的截面和共振结构对于$\rm^{76}Ge$的无中微子双$\beta$（0$\nu\beta\beta$）衰变搜索、核天体物理的$s$-过程核合成，以及用于确定考古和文化遗物元素及同位素组成的中子共振俘获分析至关重要。我们报告了在中国散裂中子源Back-n设施上使用飞行时间方法，在1 eV至1 MeV能量范围内对$\rm^{75}As$中子俘获截面进行的高精度测量。在可分辨共振区，首次发现了$\rm^{75}As$(n,$\gamma$)$\rm^{76}As$反应的十九个共振结构，并解决了评估库之间的不一致性。使用$R$-矩阵代码SAMMY提取了新观测结构的共振参数。这些发现将有助于完善$\rm^{76}Ge$双$\beta$衰变搜索的半衰期和衰变常数的理论预测。基于不可分辨共振区的平均截面，计算了天体物理麦克斯韦平均截面。并在主$s$-过程和弱$s$-过程核合成所涉及的天体物理相关温度范围内，推导了$\rm^{75}As$(n,$\gamma$)$\rm^{76}As$反应速率。目前的反应速率与最近的理论预测存在显著偏差，且不确定性显著降低。

英文摘要

The cross sections and resonance structures of $\rm^{75}As$(n,$γ$)$\rm^{76}As$ reaction are critical to the neutrinoless double-$β$ (0$νββ$) decay searches of $\rm^{76}Ge$, the $s$-process nucleosynthesis of nuclear astrophysics, and Neutron Resonance Capture Analysis for determining the elemental and isotopic composition of archaeological and cultural heritage. We report a high-precision measurement of the $\rm^{75}As$ neutron capture cross sections from 1~eV to 1~MeV, performed at the Back-n facility of the China Spallation Neutron Source using the Time-of-Flight method. In the resolved resonance region, nineteen resonance structures of $\rm^{75}As$(n,$γ$)$\rm^{76}As$ reaction have been discovered for the first time, and inconsistencies between evaluated libraries has been resolved. Resonance parameters for the newly observed structures were extracted with the $R$-matrix code SAMMY. These findings will help refine the theoretical predictions of half-lives and decay constants for the double-$β$ decay searches of $\rm^{76}Ge$. Astrophysical Maxwellian-averaged cross sections were calculated based on the averaged cross sections in the unresolved resonance region. And the $\rm^{75}As$(n,$γ$)$\rm^{76}As$ reaction rates were derived over the astrophysically relevant temperature range in both the main and weak $s$-processes nucleosynthesis. The present reaction rates deviate significantly from the recent theoretical predictions, and the uncertainties are significantly reduced.

发表机构

• Institute of Modern Physics, Chinese Academy of Sciences（中国科学院近代物理研究所）
• Guangxi Key Laboratory of Nuclear Physics and Technology, College of Physics and Technology, Guangxi Normal University（广西师范大学物理科学与技术学院）
• Advanced Energy Science and Technology, Guangdong Laboratory（广东省实验室先进能源科学与技术）
• Key Laboratory of Nuclear Physics and Ion-beam Application (MOE), Institute of Modern Physics, Department of Nuclear Science and Technology, Fudan University（复旦大学核科学技术学院）
• Shanghai Research Center for Theoretical Nuclear Physics, NSFC and Fudan University（上海 theoretical 核物理研究中心）
• Institute of High Energy Physics, Chinese Academy of Sciences（中国科学院高能物理研究所）
• Spallation Neutron Source Science Center（散裂中子源科学中心）

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