Study On Thick Gas Electron Multiplier Applied For Transition Radiation Detection

The Standard Model has successfully described the basic characteristics of most of the visible matter in the universe.However,due to the difficulties of non-perturbation solution of quantum field theory and the limitations of experimental conditions,we still lack a comprehensive understanding of the internal structure of nucleons or hadrons and a deep understanding of the nature of color confinement of quantum chromodynamics(QCD).The deep inelastic scattering experiments in the Electron-Ion Collider(EIC)with high energy and high luminosity have become an important frontier for the study of the internal structure of nucleons and QCD.Various physical processes in EIC require high precision measurement of the final state particles in the reaction,among which the detection of scattered electrons plays an important role in almost all physical subjects in EIC.For electron detection in the electron-forward direction in EIC,we show a series of particle identification methods and propose the use of transition radiation detectors(TRD)to detect and identify electrons.The principle and detection methods of transition radiation are discussed,and a suitable detector scheme is selected.The traditional TRD is often based on Multi-wire proportional chamber(MWPC).However,the detection accuracy and counting rate capability of MWPC cannot meet the requirements of the future high-energy and high-luminosity EIC experiments.Therefore,a TRD scheme based on thick gas electron multiplier(THGEM)technology is discussed and proposed.Based on the performance requirements of EIC for TRD,we have studied and developed the THGEM technology.In this thesis,an experimental test platform was built,and a variety of THGEM detectors with various structures were designed and manufactured.The gain,energy spectrum,position resolution,gain uniformity and long-term operation stability of the detector were tested in detail with soft X-ray.The charge avalanche amplification process of THGEM was simulated by finite element method and Garfield++toolkit,to understand the gain evolution in THGEM.The research showed that the accumulation of charge on the surface of insulating medium,namely the charging-up effect,was the main reason of gain evolution.By deposition of diamond-like(DLC)films with high resistivity on the surface of THGEM,the charging-up effect was removed.It is difficult to control the etching precision of the metal electrode on the surface of THGEM,which is the main reason for the poor uniformity and easy ignition discharge in large area THGEM fabrication.Using the DLC magnetron sputtering deposition technology,we developed a series of resistive THGEM(RTGEM)production methods.RTGEM is simple for production,low production cost,suitable for large area application.The RTGEMs with suitable DLC resistivity and structure showed gain and energy resolution comparable to the conventional THGEM.And the RTGEMs showed good gain stability and rate capability.A large area(20cm×100cm)RTGEM detector with a gain uniformity of 12%has been made.Based on the RTGEM and resistive readout anode,the resistive well-type detector(RWELL)is studied.The RWELL configuration is even more compact,and the gain of single-stage RWELL amplification structure can reach 104 or higher.In this paper,the GEANT4 program is used to simulate the generation and detection of transition radiation.A TRD detector prototype based on THGEM was designed and manufactured,and the readout electronics system of AGET developed by the Phsyical Electronics Group of USTC was used.We tested the performance of the TRD with electron beam of 1-5GeV at the electron synchrotron(DESY)in Germany.An argon based working gas was used in the beam test,and the experimental results agree with the simulation results.The likelihood of total deposition energy is used to analyze the hadron rejection ability of the TRD.Using the performance parameters tested by the detector,the hadron rejection factor of multiple TRDs is simulated to be more than 100 times(at electron efficiency 90%)when the electron energy is in the range of 1-5GeV.The simulation results show that the hadron rejection ability of TRD can be further improved by using the location information of the transition radiation in the detector gas volume.Both the simulation and beam experiment results show that THGEM-based TRD can provide good electron identification for the future EIC.