9Be(n,g)10Be天体物理反应率的间接测量

CNO cycle is one of the key processes in the hydrogen burning, its flux is largely determined by the abundance of 12C nucleus. In high temperature environment, 9Be(n,g)10Be reaction directly affects the production of 12C nucleus. To date, few experimental information of this reaction has been available at energies of astrophysical interest, precise measurement of this reaction rates is helpful to the calculation of 12C abundance. Direct measurement of 9Be(n,g)10Be reaction is diffcult with current experimental techniques, but it can be derived by the neutron spectroscopic factor of 10Be. Several experiments have been performed to study the neutron spectroscopic factor of 10Be, but the results have a big difference with each other. In order to clarify this discrepancy, new measurement is highly needed. In this project, the angular distribution of 13C(9Be,10Be)12C reaction will be measured at the Q3D magnetic spectrometer of the HI-13 tandem accelerator, and then the neutron spectroscopic factor of 10Be will be derived via the DWBA calculation, finally the realiable astrophysical reaction rates will be deduced.

CNO循环是恒星演化过程中氢燃烧的主要途径之一，其反应流量在很大程度上决定于种子核12C的数目。在高温环境中，9Be(n,g)10Be反应对12C的产生有一定影响，测量其天体物理反应率有重要意义。目前该反应在天体物理感兴趣能区缺乏实验数据，在现有技术条件下直接测量难度极大，我们可以通过10Be中子谱因子对该反应进行间接测量。目前国际上10Be中子谱因子的研究结果存在3倍左右的差异，有必要采取一个全新的实验方案对该谱因子进行重新测定。本项目计划在北京HI-13串列加速器Q3D磁谱仪上对13C(9Be,10Be)12C反应角分布进行精确测量，通过扭曲波玻恩近似(DWBA)理论分析，导出准确的10Be中子谱因子，结合辐射俘获理论给出9Be(n,g)10Be天体物理反应率，为研究CNO循环种子核12C的产生提供可靠数据。

恒星演化过程中CNO循环是氢燃烧的主要途径之一，一般在温度高时CNO循环占据主要因素，温度低时pp反应链占据主要因素。对于CNO循环，其反应流量在很大程度上决定于种子核12C的数目。在比较高温的环境中，9Be(n,g)10Be反应会影响12C的产生，其天体物理反应率的测量有非常重要的意义。目前该反应在天体物理感兴趣能区缺乏实验数据，在现有技术条件下直接测量难度极大，我们通过间接测量方法对10Be中子谱因子进行了研究。该项目采取了一个全新的实验方案，对13C(9Be,10Be)12C反应角分布进行精确测量，通过扭曲波玻恩近似(DWBA)理论分析，导出准确的10Be中子谱因子，该结果与转动不变壳模型理论及曾敏尔等的评价结果基本一致，解决了10Be中子谱因子国际上存在3倍左右的差异。并结合辐射俘获理论给出9Be(n,g)10Be天体物理反应率，为研究CNO循环种子核12C的产生提供了可靠数据。