The Design Of Read-Out Prototype Circuit Of Plastic Scintillator Detector In Sn-101 Level Lifetime Measurement Experiment

Testing particle models under extreme conditions is one of the main topics in the field of nuclear physics.As the heaviest self-conjugated(N=Z)"double magic nucleus" known to date,Sn-100 is an ideal experimental particle for studying protons and neutrons under extremely stable conditions.However,it is difficult to generate its nuclide,the core of which is difficult to excite.Therefore,in the framework of the shell model of nuclides in this region,the nuclide Sn-101,which differs by only one nucleon from the double magic core,is an ideal target for studying the effect of single particle excitation of protons and neutrons.The Institute of Modern Physics of the Chinese Academy of Sciences proposes to conduct the Sn-101 level lifetime measurement experiments,using the Spectrometer for Heavy Atoms and Nuclear Structure(SHANS)at the Heavy Ion Research Faclity in Lanzhou(HIRFL).The target chamber in SHANS consists of the Plastic Scintillator Detector,the Veto Detector,the Clover Detector and La Br3 Detector.The Plastic Scintillator Detector(PSD)is located in the center of the chamber.The experiments utilize the fast time response of the PSD and the Silicon Photomultiplier(Si PM)to detect the double α events,requiring the readout electronics system to have both high precision time and energy resolution to identify the Sn-101 target products.In this thesis,a study on the readout electronics of PSD is carried out for the PSD’s readout requirement of the SHANS,and a multi-channel read-out circuit is designed with a high count rate and high resolution.In the prototype circuit,the energy measurement adopts the group’s self-developed filter chip and high-speed ADC for waveform digitization,and algorithms including baseline recovery,digital integration is implemented in FPGA to realize charge extraction,and the impact of algorithms on the energy resolution is studied to propose optimized solutions.Finally,a set of optimal algorithms is designed in this system.The time measurement is achieved using leading-edge discrimination technology consisting of a fast amplifier and high-speed comparator,combined with time-digital conversion(TDC)based on FPGA.Besides,an overall scheduling architecture is designed in FPGA,which solves the time-location correlation problem of physical events in real time on the one hand,and optimizes hardware resource consumption by proposing the minimum scheduling planning method.Based on the above research,the Multi-channel Processing Unit has been successfully designed,and the prototype circuit has been completed to be tested.The energy resolution accuracy is better than 7.16 ‰ Full Width at Half Maximum(FWHM);the time resolution accuracy is better than 106 ps FWHM;the system dead time is 400 ns;the multi-channel consistency is better than 6.8 ‰,the performance is better than the design requirements.In terms of algorithm design,the energy resolution is optimized about 10.13% than before by using the area integral algorithm based on the trapezoidal element;the characteristic spectral lines avoid drifting by using the sliding baseline recovery algorithm;multi-events are synchronized in time and location dimension by using overall scheduling architecture;the hardware resource consumption of FPGA is effectively reduced by 77.03 % than before by using the minimum scheduling planning method.Finally,cosmic rays are used to test the Plastic Scintillator Detector and read-out electronics,and the energy spectra after calibration accord with the Landau distribution.The test results show that the MultiChannels Processing Unit’s function and performance meet the application requirements.