Study On Readout Electronics Of LET Spectrometer For Space Radiation Detection

Space radiation,which is mainly composed of galactic cosmic rays,solar particle events and earth radiation belts,will cause non-negligible harm to astronauts and semiconductor devices in spacecrafts.In order to quantify the impact of space radiation,scientists have carried out research related to linear energy transfer(LET)detection of space radiation.The commonly used LET detection instruments in the world include passive detectors such as nuclear emulsion and CR-39,and active detectors such as TEPC,DOSTEL,RRMD series and BIRD,as well as domestic radiation environment measurement module in the space capsule.Compared with the passive detectors,the active detectors can distinguish the particle type and monitor the radiation in the spacecraft in real time,and the detection threshold is also lower.However,the existing active detectors have high measurement uncertainty,and the obtained LET spectrum is greatly different from the model,which is not conducive to a comprehensive understanding of the space radiation environment LET.The probe part of the LET spectrometer for space radiation detection uses a silicon telescope composed of three-layer double-sided silicon strip detectors,which has the ability to measure radiation in real time and with high accuracy.After investigation,the spectrometer with track measurement uncertainty less than 4%can obtain the LET spectrum consistent with the model.Based on this requirement,this paper carries out a series of simulations and analysis,and carries out detector selection.Based on the needs of space radiation detection and the characteristics of doublesided silicon strip detector,this paper carries out the research of readout electronics methods.Firstly,the readout scheme of silicon strip detector in internationally famous space physics experiments is investigated;Secondly,the signal measurement scheme and data readout scheme are determined according to the signal characteristics of the detector and the needs of LET detection.Finally,according to the design basis and index requirements of electronics,this paper proposes a prototype readout electronics system design scheme.After the design of the scheme is completed,the readout electronics of doublesided silicon strip detector is built in the laboratory to verify the feasibility of the scheme.The core of verification electronics is multi-channel ASIC(Application Specific Integrated Circuit)SKIROC2a.Because it can only measure the positive polarity signal,this paper designs a polarity reversal module to reverse the polarity of the detector’s ohmic surface signal.Validate the test results of electronics,and prove the feasibility of charge measurement scheme and position measurement scheme.On this basis,this paper uses the same readout scheme to design the prototype readout electronics of the LET spectrometer,which is composed of the front end part and the back end part:the front end is composed of three layers of Front-End Electronics(FEE),and the FEE uses multi-channel ASIC,VATA462,for amplification,filtering,shaping and peak digitization of the detector signals;The back-end part is composed of Data Collection Module(DCM),data acquisition and control software.The data collection electronics is responsible for collecting the data of the front-end part,providing DC power for the whole readout electronics,and providing bias voltage for the detectors.In this paper,the electronic performance tests are carried out.The test results show that the electronic noise is less than 0.1 fC,and the dynamic range of 7000 times can be achieved,and the integral nonlinearity is not more than 4%.Subsequently,the detector joint debugging test was carried out.After the detector was installed,the noise of all channels in electronics was less than 0.3 fC.The single-layer detection unit composed of front-end electronics and DSSD is used to measure the standard hybrid source.The test results show that the energy resolution of the readout system can reach 2.24%at 4.65 MeV;The cosmic ray is tested,and the energy spectrum shape and MPV value are consistent with the theoretical results,which proves that the readout system can effectively detect the MIP signals.After completing the performance test,this paper carried out the joint test of the prototype readout electronics system and the silicon telescope.In the neutron radiation field,according to the hit position of recoil proton on the multi-layer detector,the track reconstruction has been successfully carried out in this test,and the obtained LET spectrum of target particle is consistent with the simulation results of Geant4.The above test results show that the readout electronics method proposed in this paper can meet the readout requirements of the LET spectrometer for space radiation detection.