核天体物理学是一门利用核物理学手段研究天体物理学问题的交叉学科。在核天体物理学的核反应实验测量中，主要关心与元素演化相关联的核反应。天体网络计算表明 AGB星是 19F 可能的合成场所，天文学观测也给出了 AGB 星中 19F 合成的证据。19F(p, α) 16O反应是 19F 的破坏反应，其反应率的精确确定对于 AGB 星中 19F 核合成网络计算具有重要意义。在对中国锦屏地下实验室的 19F(p, αγ) 16O 反应道直接测量结果进行 R 矩阵分析时，其低能区的天体物理 S 因子受到一个近质子分离阈共振的影响较大。由于这个共振的能级非常接近质子分离阈值，通过直接测量难以完全覆盖该共振，需要通过间接测量方法确定该共振的能级参数。

目前已有两项 19F( 3He, d) 20Ne 实验，给出的该能级能量结果分别为阈下和阈上，相差 36 keV。在本工作中，我们希望借助一个新的转移反应体系 19F( 7Li, 6He) 20Ne 来澄清这一分歧。本实验在中国原子能科学研究院北京 HI­13 串列加速器的 Q3D 磁谱仪终端上完成。实验中使用 7Li 束流轰击 C 衬底上蒸镀的 LiF 靶，将位置灵敏型硅探测器放置在 Q3D 磁谱仪的焦平面上，在固定测量角度下对反应出射的 6He 粒子进行长时间累积测量。实验利用 Q3D 磁谱仪的高能量分辨特性，选取合适的 20Ne 参考能级，通过能级间相对位置确定待测量能级的能量为 12.851 ± 0.008 MeV。该结果与较新的 19F( 3He, d) 20Ne 实验结果和中国锦屏地下实验室直接测量结果 R 矩阵分析时采用的能级参数在误差范围内保持一致，基本确定了最新的 R 矩阵分析选取的该能级对应的共振能量合理，最新测量的能级能量对于天体过程的影响有待进一步分析。

Nuclear astrophysics is an interdisciplinary research field studying astrophysics problems by nuclear physics method. Nuclear reactions concerning evolution of elements are focused in the experimental measurements of nuclear astrophysics. Astrophysical network calculations indicate that AGB stars are the possible sites of 19F synthesis, while astronomical observations also provide the evidence. 19F(p, α) 16O is a destruction reaction of 19F. The precise determination of its reaction rate is of great importance in the 19F synthesis network calculation of AGB stars. The astrophysical S factor of 19F(p, αγ) 16O in the low energy area is influenced by a resonance near the proton threshold during the R matrix analysis of the direct measurement results in the China JinPing Underground Laboratory. It’s nearly impossible to cover the resonance totally by direct measurement as the corresponding state is too close to the proton threshold. The parameters of this state need to be measured with indirect methods.

Two different values of the level energy with a difference of 36 keV was provided by two

19F( 3He, d) 20Ne experiments. The level energies were deduced to be a little lower and higher than the proton threshold respectively by the two experiments. In the present work, a new transfer system 19F( 7Li, 6He) 20Ne was adopted to declare the difference. The experiment was performed on the Q3D magnetic spectrograph terminal at the HI­13 tandem accelerator of the China Institute of Atomic Energy in Be?ing. LiF targets evaporated on C foils were bombarded by 7Li beam. Position sensitive silicon detectors were placed on the focal plane of the Q3D magnetic spectrograph. The outgoing 6He particles were detected under a certain angle continuously. A few suitable 20Ne states were adopted as references to determine the required level energy by the relative positions. The level energy was deduced to be 12.851 ± 0.008 MeV with the high energy resolution of the Q3D magnetic spectrograph. The value agrees with the latest 19F( 3He, d) 20Ne experimental result and the parameter adopted in the R matrix analysis of the direct measurement results in the China JinPing Underground Laboratory within the uncertainties. The resonant energy employed in the latest R matrix analysis was basically confirmed to be reasonable. The effect of the latest level energy on the astrophysical process needs to be analyzed further.