The Study Of An EM Calorimeter For Searching Dark Matter In Space

Astronomical observations show that the majority of the gravity matter is dark matter in Universe. The matter which has been seen through the electro-magnetic and strong interaction people knows is only a small part in the universe. Although dark matter has been widely recognized by astronomical observations, the nature of dark matter and dark energy is still unknown. It’s said: "Dark matter and dark energy are the two clouds that obscured the beauty and clearness sky of physics and astronomy in twenty- first century ". It is recognized that human knowledge will have another major leap forward when you will answer the two“dark”quenstions experimentlly and theoretcally. Since the understanding of dark matter and dark energy problems need the development and creation of series of new theories and new technology. The breakthrough will bring a major revolution in physics and astronomy.In recent years, the research of dark matter becomes very“hot”in the Astro-particle physics field. China has brought in great effort in promoting the dark matter detection program. Tsinghua University, Shanghai Jiaotong University have established underground laboratory in Jinping Moutain, searching for direct signature of dark matter candidate - WIMP. Other efforts are made on detecting the evidence of existence of dark matter in Universe by using our satellite platform.This thesis main work is study the performance of the detector for the dark matter measurement in Space. It includes the following two main parts:●Simulation study for the conception design of EM calorimeter in Space:1. Using Monte Carlo-codes to simulate detector response of electromagnetic calorimeter for high energy protons, electrons and gamma rays. The results provide the basis for the design of EM calorimeter in Space.2. The separation ability of electrons and protons is discussed in detail. Justifying the feasibility of picking up the rare e/γevents from 105 to 106 proton background events in Space.3. Search for the optimum position of the“absorber”for gaining the optimum PID capability.4. And use Monte Carlo simulation to calculate the“Physical Acceptance”that used to instead the traditional“Geometrical Factor”of the detector. It is a key parameter of the EM calorimeter for space observation.5. The trigger system was also discussed in the last of this part.●Experimental study for the key issue and key parameters of EM calorimeter in Space1. In Experiment, we designed and built the platform for characterizing BGO crystals experimentally. The essential data of BGO crystals will be provided using the platform. The fluorescence quenching effect was researched preliminary that use proton beam in CSR. The result shows that the fluorescence quenching effect of BGO cann’t be described by Birk Law.2. A large dynamics readout system (covering ~106) is one of the key issues for the Ecal in Space. A test setup consists of LED and fanning out fiber bunch has been built. A readout system of PMT coupled with FEE has been carefully study. The test results show that the readout system could cover from 0.5 MIPs to 1.5×10~5 MIPs. The design of the readout system and the test results has been confirmed and accepted by the evaluation committee assigned authoritatively by CAS.3. A cosmic test platform which consists of 24 BGO array with PMT+FEE and a DWC (Delay Wire Chamber) tracking system has been built and was running for MIPs-data taking. The key calibration coefficients of energy deposition per ADC count for every dy7 readout channel have been preliminary obtained. By means of this platform a lot of reference data like calibration coefficients on ground will be obtained and updated. The trigger setting and timing for analog and logic signals will be tested in the whole R&D proceeding for the real prototype of Ecal.in Space 4. The database was also designed for storing the test data of each elements ofthis detector. The database will be updated following the whole proceeding from R&D of real prototype on ground to the Space Ecal run in flight. It will provide very important reference data for calibration, monitoring and data analysing.5. The last of this part is the review of this paper and outlook for the project in future.