SOI硅微剂量探测器对中子和伽马辐射场线能谱测量的GEANT4模拟研究

GEANT4 simulation of silicon-on-insulator microdosimeter for monitoring lineal spectra of neutron and gamma mixed field

绝缘体上硅(SOI)硅微剂量测量系统可以通过测量中子和伽马混合辐射场的线能谱来获取不同类型辐射的剂量当量贡献。本文根据SOI硅微剂量探测器物理设计,采用GEANT4软件建模对Cf-252中子和伽马混合辐射场及Co-60伽马辐射线能谱测量进行蒙特卡罗模拟,并进一步分析了SOI探测器转换层对伽马线能谱测量的影响。结果表明,SOI硅微剂量探测器能够区分中子和伽马的剂量贡献,并且伽马线能谱峰值随着转换层厚度发生变化,有可能利用该特性实现不同贯穿深度下伽马辐射剂量贡献的测量。模拟分析结果可为SOI硅微剂量探测器设计及应用提供参考。

Lineal energy spectra of novel SOI （silicon -on -insulator） microdosimeter and detector response in Cf- 252 neutron and gamma mixed field and Co -60 gamma radiation field were simulated with GEANT4. The simulated results were compared with the TEPC monitoring experiments with good consistency. Some differences are identified and discussed. The effects of different conversion layer thickness on lineal energy spectra were analyzed. Through the simulation, it can be seen that the SOI detector could be used to distinguish the contribution of neutron from gamma. We also found that the thicker conversion layer could increase the peak values of gamma lineal spectra, which may be used for gamma dose measurement at various depth of tissue. These results provide valuable information for the design of the SOI microdosimeter.