基于GEANT4蒙特卡罗算法的闪烁体探测器建模与优化

Modeling and Optimization of Scintillator Detectors Based on GEANT4 Monte Carlo Algorithm

核设施工作场所的辐射场中往往同时存在β射线和γ射线,现有的成熟设备几乎无法同时测量混合场中的β和γ能谱,采用传统二次测量方法误差较大.针对β-γ混合场中射线互相干扰的难题,本文基于GEANT4对叠层闪烁体探测器建立蒙特卡罗模型,仿真模拟β和γ粒子在探测器中的能量沉积,研究双层和三层结构叠层闪烁体探测器中β粒子和γ光子的最优判别方案,以及不同的结构和材料对探测器甄别性能的影响.模拟结果显示,加入薄层塑料闪烁体后,三层结构的闪烁体探测器对γ粒子的误甄别率显著低于双层结构,最后比较4种不同材料的闪烁体组合对甄别性能的影响,仿真结果显示第二层采用BC444材料的甄别性能最优.

The radiation field in the workplace of nuclear facilities often contains both beta and gamma rays,and the existing mature equipment can hardly measure the beta and gamma spectra in the mixed field at the same time.The traditional secondary measurement method has a large error,and in order to solve the problem of mutual interference of gamma rays in theβ-γmixed field,this paper establishes a Monte Carlo model based on Geant4 stacked scintillation detector.The energy deposition ofβandγparticles in the detector was simulated,and the optimal identification scheme ofβandγphotons in the double-layer and triple-layer scintillator detector was studied,as well as the influence of different structures and materials on the detector discrimination performance.The simulation results show that after adding thin plastic scintillator,the error detection rate of the scintillator detector with three-layer structure is significantly lower than that with double-layer structure.Finally,the effect of scintillator combination of four different materials on the discrimination performance is compared,and the simulation results show that the second layer uses BC444 material for the best discrimination performance.