锦屏深地核天体物理实验室屏蔽计算

锦屏深地核天体物理实验室（JUNA）为核天体物理关键反应的研究提供了极低本底环境，加之400 kV强流高稳定加速器的使用，使核天体物理感兴趣能区（伽莫夫窗口）的直接测量成为可能。而同时为避免加速器产生本底破坏锦屏深地实验室的超低本底环境，需估算加速器运行本底，进而对核天体物理实验室进行整体屏蔽。以屏蔽系统的初步设计方案为基础，基于中国核数据中心推荐的综合评价核数据库CENDL-NP，采用MCNP方法对其进行了模拟计算。计算过程采取了权重窗技巧与改变几何条件相结合等方法来减小方差，以提高MCNP方法在计算深穿透问题时的准确性。计算结果表明，该实验室的屏蔽系统对加速器引起的本底进行了有效的屏蔽。

Shielding Calculation of Jinping Underground Laboratory for Nuclear Astrophysics

Jinping Underground Laboratory for Nuclear Astrophysics provides ultra-low background environment for the study of nuclear astrophysics critical reaction. In addition, the use of 400 kV high current and high stability accelerator makes the direct measurement of the interested energy zone in nuclear astrophysics (Gamow window) possible. In order to avoid the damage caused by the background of accelerator to the laboratory’s ultra-low background, it’s necessary to estimate the background of the accelerator and establish the overall shielding system formal. The preliminary design of shielding system was simulated by MCNP method based on the comprehensive evaluation nuclear database CENDL-NP recommended by China Nuclear Data Center. In order to improve the precision of MCNP method in computing deep neutron penetration problem, weight window technique and changing geometric condition were used to reduce the variance. The results of calculation show that the shielding system of the laboratory effectively reduces the background caused by the accelerator.