Development Of Digital Multi-Channel System For Hpxe Detector And Algorithm Correction For Its Baseline Drift Problem

High-pressure xenon?HPXe?detector with excellent energy resolution has good physical characteristics such as wide operating temperature range,high radiation resistance,and long term performance.It has great potential for industrial applications.However,the vibroacoustic effect of the Frisch grid seriously affects the baseline of HPXe detector signal,causing distortion of the measured energy spectrum.To solve this problem,a digital multi-channel system based on FPGA was developed for high energy resolution detectors,besides a self-adjusting parameter baseline restoration method based on mathematical morphology was proposed and implemented in digital multi-channel system to obtain stable measurements of energy spectrum under severe baseline drift.The main research contents and achievements are as follows:?1?The hardware circuit of digital multi-channel system was designed and optimized independently.The hardware circuit includes power control module,high-speed ADC sampling module,FPGA signal processing module and USB communication module.The test results show that each module of the hardware circuit system works normally with 0-5 V input voltage range,40 MSPS sampling rate,14-bit sampling accuracy and 114 K logic resources.The hardware circuit has excellent performance,such as low power ripple?25 mV?,low power consumption?900 mW?,high stability?continuous operation for 8 hours?and compact?6.3×6.3 cm²?.?2?The multi-channel signal processing algorithm was designed.The algorithm includes trapezoidal shaping,cusp-like shaping,pile-up rejection,amplitude extraction,spectral line generation and USB communication.Besides,energy spectrum can be directly acquired by the host computer.The simulation results show that the algorithm can work normally with accurate timing.The CZT detector was used to verify the performance of the digital multi-channel system.The results show that the total energy spectrum channel is 2048,the energy resolution at 662 keV is 2.59%,the energy linearity is99.9%,and the full energy peak drift of ¹³⁷Cs is less than 2 channels within continuous operation for 8hours.?3?The baseline restoration based on mathematical morphology was proposed and improved for the baseline drift of HPXe detector.The feasibility and shortcomings of the traditional mathematical morphology baseline restoration algorithm to restrain the baseline drift in digital multi-channel system were analyzed,and an improved method was proposed.The improved baseline resolution method based on mathematical morphology,which can adjust the parameter automatically in real time according to the characteristics of the baseline,was proposed to obtain superior baseline restoration.The energy spectrum with the correction algorithm was virtually unaffected by the 900 mV baseline drift,it almost overlapped with the standard spectrum which is measured without baseline drift,and the energy resolution at 662 keV can be maintained at around 2.64%under 900 mV baseline drift.The research content has positive effect for promoting the development of domestic digital multi-channel system.It is expected to solve the problem of baseline drift caused by vibroacoustic effect in HPXe detector,improve the stability of HPXe detector energy spectrum measurement under outdoor conditions,and expand its application range.Besides,it can provide a new solution to the problem of baseline drift for other radiation detectors.