基于伴随粒子的快中子成像系统角分辨研究

不同于传统的快中子成像系统，采用伴随粒子成像技术无需机械准直即可消除大部分γ射线和散射中子的干扰，实现对厚重物体的高对比度成像。角分辨是影响系统成像质量的一项重要参数。通过理论分析，研究了入射离子的初始动量、靶点尺寸和探测器空间分辨等多个因素对系统角分辨的影响。利用基于GEANT4的模拟程序，计算了不同参数下被标记中子出射角分布的二维图像。分析及模拟结果表明，靶点直径和α探测器空间分辨率是影响角分辨的重要因素。为满足系统角分辨小于1°的设计目标，入射离子的初始动量变化范围应较小，靶点直径应小于1 mm，同时α探测器的空间分辨率应小于0.5 mm。

Study on Angular Resolution of Associated Particle Fast Neutron Imaging System

Different from the traditional fast neutron imaging system, the use of associated particle imaging technique can eliminate the interference of most γ-rays and scattered neutrons without mechanical collimators, and make it possible to perform fast neutron imaging of thick and heavy objects with excellent contrast. Angular resolution is an important parameter that affects the system performance. Through theoretical analysis, the effects of the incident ion initial momentum, target spot size and detector spatial resolution on the system angular resolution were studied. The two-dimensional images of neutron emission angle distribution under different parameters were calculated using the GEANT4 simulation program. The analysis and simulation results indicate that the target spot size and spatial resolution of α detector are important factors that affect the angular resolution. To obtain a system angular resolution of less than 1°, the initial momentum variation range of incident ions should be small, the target spot diameter should be less than 1 mm, and the spatial resolution of the α detector should be less than 0.5 mm.