CEE-TPC中GEM读出探测器传输性能实验研究

Gas Electron Multiplier (GEM) has received extensive attention in recent years due to its advantages such as good position resolution and isotropic two-dimensional structure. The Cryogenic and Dense nuclear matter Experiment (CEE) being constructed at HIRFL - CSR also plans to use GEM as the readout detector of the Time Projection Chamber (TPC). The transmission characteristics of the GEM detector under different electric field conditions have a significant impact on the effective gain and energy resolution of the detector. This paper studies the influence of the electric field in the drift region and the induction region on the transmission characteristics of a single - layer GEM detector; subsequently, it studies the influence of the voltage distribution and the electric field in the transmission region on the charge transmission performance of a double - layer GEM detector. The results show that in single - layer and multi - layer GEM detectors, the electric fields in the drift region, the transmission region, and the induction region mainly affect the charge transmission performance of the detector by changing the electron transmittance and the GEM avalanche electric field intensity and distribution, and further affect the effective gain and energy resolution of the detector. The above experimental results indicate that the GEM detector is an ideal choice for the CEE - TPC readout detector, and at the same time, the test results also provide a reference basis for the selection of the working points of multi - layer cascaded GEM in the TPC.

气体电子倍增器(GEM)因其具有较好的位置分辨以及各项同性的二维结构等优点,近年来受到了广泛的关注,在HIRFL-CSR上正在建设的低温高密核物质测量谱仪(CEE)也计划使用GEM作为TPC的读出探测器。不同电场条件下GEM探测器的传输特性对探测器的有效增益及能量分辨有较大影响。文中研究了单层GEM探测器中漂移区电场及感应区电场对探测器传输特性的影响;随后研究了双层GEM探测器的电压分配及传输区电场对探测器电荷传输性能的影响。结果表明,在单层及多层GEM探测器中,漂移区电场、传输区电场及感应区电场主要通过改变电子透过率和GEM雪崩电场强度及分布影响探测器的电荷传输性能,进而影响探测器的有效增益及能量分辨。以上实验结果表明GEM探测器是CEE-TPC读出探测器的理想选择,同时测试结果也为TPC中多层级联GEM工作点的选择提供了参考依据。