采用三维中子-光子耦合输运蒙特卡罗程序JMCT，对神光Ⅲ主机靶场进行精细几何建模，使用该模型通过计算获得了DD内爆聚变中子及伽马射线在靶场环境的空间分布以及能谱和飞行时间谱。根据计算结果对散射中子和伽马射线的特性进行了讨论，并定量分析了散射中子噪声和伽马噪声分别对下散中子产额测量和高能X射线照相的影响。研究结果表明：必须进行有效的辐射屏蔽设计才能使下散中子产额测量和高能X射线照相的信噪比优于10。

A detailed model of Shenguang Ⅲ target bay was developed by JMCT, a 3-D neutron and photon transport Monte Carlo code. Using this model, calculations were performed to obtain the spatial distribution, energy spectra and time-of-flight spectra of fusion neutron and gamma radiations from DD implosions. Characteristics of scattered neutron and gamma radiations were discussed based on the calculated results. In particular, the impacts of neutron noise on down-scattered neutron yield measurement and gamma noise on high energy X-ray radiography were analyzed quantitatively. The results showed that in order to obtain a signal-to-noise ratio better than 10, effective radiation shielding was required for both down-scattered neutron yield measurement and high energy X-ray radiography.