基于厚GEM的宽量程γ剂量率探测器研究

Study of a Wide Range Gamma Dose Rate Detector Based on THGEM

厚型气体电子倍增器是一种近10年迅速发展并逐步在多个领域得到应用的气体探测器,具有死时间小、动态范围大、n/γ排斥比高等优点。除了在高能粒子探测、辐射成像等方面的应用外,厚GEM在辐射防护领域也表现出较好的应用潜力。该研究对厚GEM进行建模,仿真计算不同结构、不同灵敏区尺寸以及不同GEM膜厚度时,厚GEM探测器对γ射线的探测效率,在此基础上采用新型基底材料和自主印制电路板技术设计并制作了具有良好稳定性的厚GEM膜,其单层增益可达2×10^(4),工作电压范围超过150 V,探测效率满足辐射监测的需求。利用新研制的GEM膜制作了探测器,设计并搭建了计数模式和电流模式两种信号读出电路。经测试,该探测器对^(137)Cs和^(60)Co的γ射线实现了0.3×10^(−6) Gy/h~8 Gy/h宽量程范围的γ剂量率监测。

Thick gas electron multiplier is a gas detector that has been rapidly developed in recent ten years and gradually applied in many fields,with advantages of small dead time,large dynamic range and high rejection ratio of n/γ.In addition to its applications in high-energy particle detection and radiation imaging,the thick GEM also shows good application potential in the field of radiation protection.In this paper,the thick GEM was modeled,and the detection efficiency of the thick GEM detector for gamma rays was simulated and calculated with different structures,different sensitive area sizes and GEM film thicknesses.On this basis,the thick GEM film,the key part of the detector,was designed and fabricated with new substrate materials and autonomous printed circuit board technology,which showed good stability and high gain of up to 2×10^(4) for a single-layer film,working voltage range of more than 150 V,and detection efficiency meeting the requirements of radiation monitoring.In this paper,a detector was fabricated with the newly developed GEM film,and two kinds of signal readout circuits,counting mode and current mode,were designed and built.The experimental test shows that the detector can monitor the gamma-ray dose rate of ^(137)Cs and ^(60)Co with a wide range of 0.3×10^(−6) Gy/h~8 Gy/h.