宇宙重元素起源是核天体物理领域的重要前沿课题，p-过程是合成丰质子侧的重元素的主要途径。74Se是最轻的p-核，恒星模型预言的74Se丰度比天文观测高出3倍，主要原因是核反应率数据比较缺乏或精度不够。灵敏度研究表明，74Ge(p,γ)75As是影响74Se丰度的最关键核反应。对于典型的恒星环境，74Ge(p,γ)75As反应伽莫夫窗口为1.2-3.8MeV，而当前国际实验最低测到1.6MeV。.本项目拟在中国原子能科学研究院计量站的1.7MV强流串列加速器上，直接测量74Ge(p,γ)75As的反应截面。在前人工作基础上，本项目将结合使用分立伽玛测量法和能量全吸收测量法，拟将74Ge(p,γ)75As反应截面测量推进到国际最低能量1.4MeV，并提高更高能区现有数据的精度，为理解轻质量区p-过程核素合成的疑难问题提供关键数据。

The origin of heavy elements in the universe is an important frontier in the field of nuclear astrophysics. The p-process is mainly responsible for synthesizing the heavy elements on the proton-rich side. 74Se is the lightest nucleus in the p-process. Its abundance predicted by the stellar model is three times higher than that of astronomical observations. The main reason is that the nuclear reaction rate data are lacking or their precision is not enough. Sensitivity study shows that 74Ge(p,γ)75As is the most critical nuclear reaction affecting 74Se abundance. For a typical stellar environment, the Gamow window of the 74Ge(p,γ)75As reaction is 1.2-3.8 MeV, while so far the previous experiments have been performed down to 1.6 MeV..The project is to directly measure the reaction cross section of 74Ge(p,γ)75As using the 1.7MV high-current tandem accelerator of the China Institute of Atomic Energy. This project will combine the method of individual gamma measurement and the method of the summed gamma energy measurement, and propose to perform measurement of the 74Ge(p,γ)75As reaction cross-sections down to an energy of 1.4 MeV and improve the precision of the data at higher energies. The project aims at providing key data for understanding the origin of the light elements in the p-process.