关键词: 气体电子倍增器/
微网结构气体探测器/
增益
English Abstract
Measurement and simulation of the hybrid structure gaseous detector gain
Zhang Yu-Lian1,2,3,Qi Hui-Rong2,3,
Hu Bi-Tao1,2,
Wen Zhi-Wen1,2,3,
Wang Hai-Yun2,3,4,
Ouyang Qun2,3,
Chen Yuan-Bo2,3,
Zhang Jian2,3
1.School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000, China;
2.State Key Laboratory of Particle Detection and Electronics, Beijing 100049, China;
3.Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China;
4.University of Chinese Academy of Sciences, Beijing 100049, China
Fund Project:Project supported by the National Key Programme for S&T Research and Development, China (Grant No. 2016YFA0400400), the National Natural Science Foundation of China (Grant No. 11675197), and the Innovation Fund of Institute of High Energy Physics, Chinese Academy of Sciences.Received Date:16 March 2017
Accepted Date:24 April 2017
Published Online:05 July 2017
Abstract:As one of the most popular micro pattern gaseous detectors, gas electron multiplier (GEM) has been extensively studied and applied in recent years. The studies of the detector gain measurement and simulation are important, especially on a low gain scale. Traditionally, the gain measurement is realized by measuring the current or the pulse height spectrum. The former needs complicated electronic chain calibration and the latter needs necessarily to calculate the primary electron number. In this paper, an alternative method to determine the effective gain of GEM is introduced. The GEM gain can be precisely achieved through a gaseous detector of hybrid structure which combines GEM with micro-mesh gaseous structure (MM). The hybrid structure is called GEM-MM for short. The GEM-MM detector consists of drift cathode, standard GEM foil, stainless steel micro mesh, and readout anode. In this detector, the space between the cathode and the GEM foil is called drift gap and the other space between the GEM foil and the mesh is named transfer gap. When the X-rays irradiate into the gas volume of GEM-MM, the primary ionization occurs in both regions. Photoelectrons in the drift gap transfer from the drift region to amplification sensitive areas of the GEM and the MM detector while those in the transfer region are only amplified by the MM detector. In the energy spectrum of 55Fe, there is a clear energy profile including two sets of peaks. The gain of GEM can be easily obtained from the energy spectrum. Meanwhile, detailed simulations are carried out with Garfield++ software package. Simulation of the electron transport parameters has been optimized. and the gains of GEM detector are also calculated for three different gas mixtures. Experimental results of the gains ranging from 3 to 24 are obtained. The gains of GEM under different working voltages are studied precisely from the spectrum measurements. The Penning transfer rate could reach 0.32±0.01 when the simulated value matches the measurement within 1σ error.
Keywords: gas electron multiplier/
micromegas/
gain
