Study On Readout Electronics System For The Gamma-Gamma Collider

Various types of particle colliders have been proposed and carried out internationally to study the features of elementary particles,and the gamma-gamma collider is one of the research hotspots.The high-energy gamma-gamma collider with the center-of-mass energy of hundreds of GeV provides lower energy than the electron-positron collider to produce Higgs particles,and the reaction cross section is larger,making it an attractive project of the Higgs factory.The gamma-gamma collider with the energy of hundreds of MeV to a few GeV plays an important role of the new physics research of elementary particles(charm quarks and bottom quarks,etc.).The gamma-gamma collider with the energy of several MeV is of great significance to the research of γγ scattering and the Breit Wheeler(BW)pairs production.Considering that the high-energy gamma-gamma collider requires high-energy electron beams with laser beams of high collimation and high power rate,these situations are currently difficult to meet the requirements of high-energy experiments,but can be applied to the research of low-energy gamma-gamma collider.On such experimental circumstance,the Institute of High Energy Physics(IHEP)of China proposed to build the world’s first gamma-gamma collision(yy collider)based on the existing mature accelerator and laser technology in China.The initial target is to achieve the gamma photon collision with the 1～2 MeV center-of-mass energy,to further study the features of the gamma photon from the collision products.The main research of this subject is to provide a suitable readout electronics system for the γγ collider,and achieve the detection of collision products.According to the output signal characteristics of the γγ collider detector(plastic scintillator+CsI(Na)+SiPM)and the compact vacuum detection area,this thesis confirms the readout requirements of electronics:the event rate of the collider is 50～100 Hz,the readout-channel number is 1426,the dynamic input range is 1 V,the noise RMS is lower than 3 mV,and energy measurement and pariticle discrimination are required for collision reconstruction.After the analysis and research of electronics system in similar international experiments,the readout electronics of low-power,1 GHz high-samp ling-rate is carried out using waveform digitization technology based on SCA ASIC,and applied to simultaneously record energy and time information of the output signal generated from the gamma-gamma collision.In order to verify the key design performance of the readout electronics,this thesis provides the design of the readout electronics based on DRS4 chip waveform storage and ADC digitization,and verifies the effects of waveform digitizaiton,clock design,chip drive capability,FPGA logic design,etc.The transmission of detected data,trigger clock distribution and configuration command control are accomplished via the optical fiber.After the analysis of the test results,the waveform digitization based on SCA ASIC is feasible to the experiment,the appropriate input buffer chip is determined,and the current driving ability of the FPGA and DAC ensure them to drive more chips.The optical fiber transmission is stable and reliable.Based on the verification results,the thesis carried out the design of the prototype readout electronics,which consists of 8 front-end boards(FEE)and 1 back-end data acquisition board(DAQ).The front-end board can process 180-channel signals from the detectors using waveform digitization technology,and the packaged data is sent to the DAQ board via high-speed optical fiber.After the performance test and data analysis of the electronic system(2 FEE boards+1 DAQ board)in the laboratory,the FEE board meets the dynamic range requirement of 1 V,the noise RMS of analog channels is less than 1.6 mV,the time deviation of sampling interval is less than 42 ps,and the optical fiber link and ethernet transmission work normally,which provides important reference value for the engineering readout electronics design of the γγ collider.After the performance test of the electronics system,the joint-test of the prototype electronics with one detector module which imitates the detection unit of the collider has been carried out,and the results proves that the readout system has the ability of particle discrimination.Besides,the joint-test with the multilayer plastic scintillator detectors was carried out,and the energy spectrum of single plastic scintillator and adjacent-channel correlation results were acceptable,and the cosmic ray track of multi-layer scintillations was reconstructed successfully.These test results prove that the electronic system is working normally,which provides a strong guarantee for the subsequent development of the γγ collider.