Design Of High Speed Nuclear Signal Acquisition System Based On CLYC Detector

In recent years,a new inorganic scintillator material Cs2 Li YCl6:Ce(CLYC)has been developed.It can interact with gamma rays and neutrons at the same time,but the output signal shapes of the two are different.Identifying the type of incident particles by the difference in the shape of the output signal makes the CLYC scintillator capable of detecting both neutrons and gamma rays.The use of CLYC's n/? dual-ray detection capability and high gamma-ray energy resolution for the measurement of n/? mixed radiation fields can simplify the detection system and improve portability.At present,the domestic research on CLYC detectors is still in its infancy,often using high sampling rate oscilloscopes to collect CLYC detector signals before data analysis and processing.This method has the disadvantages of complicated operation,and long time consumption.To this end,this paper designs a high-speed dual-channel nuclear signal acquisition system based on FPGA.Complete signal waveform data is obtained by high-speed sampling,and the n/? signal is discriminated in combination with the waveform discrimination algorithm.System testing was carried out in the radiation field of Am-Be neutron source.The research results achieved in this paper are as follows:1.This paper designs a current sensitive preamplifier for the front end of the detector composed of CLYC crystal and photomultiplier tube(PMT),which amplifies the current pulse signal output by the PMT,ensuring that the nuclear signal output by the detector can be stably transmitted to the back end Acquisition circuit.2.This paper designs a high-speed dual-channel nuclear signal acquisition system based on the characteristics of short rise time and high signal-to-noise ratio of nuclear signal.The circuit noise level of the high-speed dual-channel acquisition system designed in this paper is low,the nuclear signal recognition algorithm can accurately identify the nuclear signal in FPGA,and save the complete data of the nuclear signal,and the nuclear signal data packet can be stably transmitted to the host computer.3.Use the CLYC detector to measure the Am-Be neutron source,and use the high-speed dual-channel nuclear signal acquisition system designed in this paper to collect the nuclear signal output by the detector.The charge comparison method is used to perform pulse waveform discrimination(PSD)on the signals collected by the 100 MSPS channel and the 500 MSPS channel.The n/? signal discrimination quality factor(Figure of Merit,Fo M)value of the 100 MSPS channel is 1.59,and the Fo M value of 500 MSPS channel is 2.12.The results show that both acquisition channels can achieve the n/? signal discrimination of the CLYC detector,and the 500 MSPS acquisition channel can achieve a better discrimination effect.