高通量下GEM探测器高压供电模式研究  

Investigation of HV Power Supply for GEM Detector in High Dose Rate

作　　者：魏堃[1,2,3] 祁辉荣[2,3] 张余炼[1,2,3] 温志文 张建[2,3] 欧阳群[2,3] 张小东[1,4] 

机构地区：[1]兰州大学核核科学与技术学院,兰州730000 [2]核探测与核电子学国家重点实验室,北京100049 [3]中国科学院高能物理研究所,北京100049 [4]Department of Nuclearengineering,University of Tennessee

出　　处：《原子核物理评论》2015年第3期335-340,共6页Nuclear Physics Review

基　　金：国家自然科学基金项目(11275224)~~

摘　　要：GEM探测器的供电一般采用电阻链分压供电模式和多路分立供电模式,在低通量X射线下测量时区别不大,但是在高通量X射线时,电阻链分压供电模式会带来饱和效应引起工作电压的变化,造成探测器工作不稳定。本研究在高通量X射线照射下,研究了有效面积为100 mm×100 mm三层级联GEM探测器的有效增益(稳定性)与不同高压供电模式的关系。通过测量不同分压电阻值(1,2,5到30 M?)的实验研究,发现随着X射线通量的增加,在电阻链分压供电模式下,出现了GEM探测器感应电极的读出电流饱和趋势,分析了可能导致饱和效应出现的原因。结果表明,当入射X射线在探测器上的有效吸收剂量不断增加时,电阻链供电模式需要调整分压单元电阻值,或者采用多路分立供电模式,从而避免因饱和效应引起的GEM探测器有效增益的变化,实现探测器稳定的工作状态。There are two methods of the HV power supply for the GEM detector. One is a HV channel divided by the resistive chain and the other is the several separate HV channels. In the smaller dose rate of X-ray, all of the methods are similar. When the dose rate increases, the resistive chain-dividing mode has more obvious saturation effect and the working voltage of the GEM detector is unstable. In the paper, a GEM detector with an effective area of 100 mm×100 mm has been studied in the high dose rate using X-tube. The unit values in the divider resistance chain are set to 1, 2, 5 and 30 M？ respectively in the test. With the resistive chain-dividing mode, the readout current of the GEM detector＇s anode tends to saturate when the dose rate of X-ray increases,and the reasons of the saturation effect are analyzed. The results indicate that the effective absorbed dose of X-ray by the triple GEMs detector reaches to the specific value and the divider resistance needs to re-select, even the several separate HV channels mode should be considered. It will keep the constant of the working voltage of the GEM detector without the saturation effect and gain variation and the performance of GEM detector is stable.

关 键 词：GEM探测器 高压供电模式 X射线 高剂量 

分 类 号：TL811[核科学技术—核技术及应用]