Design Of Six-channel Multi-parameter Digital Spectrometer System Based On List-mode

Digital spectrometer is a key component of nuclear radiation measurement and analysis.In special nuclear radiation measurement occasions,many types of nuclear radiation detectors are often used to simultaneously measure a variety of nuclear radiation information to achieve the function of nuclide decay profile measurement.Therefore,it is necessary to design a multi-channel digital spectrometer,which is currently a hot spot for research at home and abroad.Today's mainstream multi-channel digital spectrometers are mainly manufactured by foreign manufacturers.They are mostly designed with the same sampling rate,and cannot perfectly fit the measurement requirements of different nuclear radiation detectors.According to the multi-parameter measurement requirements of various nuclear radiation detectors,this paper develops a software and hardware system based on the six-channel multi-parameter digital spectrometer system based on List-mode.This system is different from the traditional multi-channel digital spectrometer,and three types of design are designed.Embedded nuclear signal processing ADC cards with different sampling rates,each embedded nuclear signal processing ADC board is fully compatible with hardware and software interfaces,and is completely electrically isolated in analog circuits and digital signal processing departments,ensuring channel-to-channel.The lowest crosstalk is only connected to the common ground in the digital communication interface.The embedded nuclear signal processing ADC boards with different sampling rates can be adapted to different types of nuclear radiation detectors,thereby obtaining more excellent flexibility,adaptability and measurement results than traditional multichannel boards with the same sampling rate.The six-channel multi-parameter digital spectrometer based on List-mode designed in this paper has six-channel simultaneous measurement function,and each channel can be set to three working modes: original waveform mode,shaping waveform mode and particle data mode(list mode);design dedicated clock Synchronization circuit,the clock synchronization accuracy between channels is less than 5ns;the spectrometer integrates a low-noise preamplifier power supply,adopts a standard NIM interface,and outputs ± 12 V and ± 24 V preamplifier power supply voltages,and the noise is less than 1m VRMS;the spectrometer and the host computer software use high-speed USB3.0 interface for data transmission,the communication data can reach 360MBps;the maximum count rate of each measurement channel of the six-channel spectrometer can reach 500kcps;The energy resolution test of GEM40P4-76 high-purity germanium detector of ORTEC company in the United States is 0.136%@1.33 Me V;the resolution test for ?50mm × 45 mm lanthanum bromide detector is 2.8%@662ke V,?45mm × 50 mm The resolution test of the cerium bromide detector is 4.28%@662ke V;the spectrometer has the measurement functions of rise time and fall time.The main research contents of this article are as follows:1.Designed three kinds of embedded nuclear signal processing ADC boards with different sampling rates,including 80 MSPS,250MSPS and 500 MSPS.In order to ensure the high energy resolution of nuclear radiation measurement,a digital trapezoidal forming algorithm is designed to accurately extract the signal amplitude.In order to ensure the high time resolution of nuclear radiation measurement,a digital constant ratio timing algorithm is designed to achieve accurate extraction of signal arrival time.2.Design a multi-channel high-speed data transmission main control backplane,use USB3.0 interface to communicate with the host computer,to achieve stable and reliable transmission of measurement data.The main control board supports sixchannel embedded nuclear signal processing ADC board card connection,and communicates with the host computer software through the USB3.0 circuit based on FT601 Q design,and the transmission speed can reach 360 MBps.3.Design synchronous clock and trigger circuit.In order to ensure the time synchronization of the data measurement of each channel of the system,a dedicated clock synchronization and trigger circuit is designed to provide a unified time reference for each channel,and the time synchronization accuracy is less than 5ns.4.Adopt isolated power supply design scheme,and design low noise front discharge power supply.In order to ensure the independence of each measurement channel of the system and reduce the interference between them,an isolated power system is designed with a linear transformer,and low-noise ± 12 V and ± 24 V power is provided to the detector preamplifier circuit according to the NIM interface standard Voltage.5.List-mode list data measurement mode.The embedded nuclear signal processing ADC board measures the multi-parameter particle information of the particle event generated by the nuclear signal in the detector,including the multiple parameters of the particle event rise time,fall time,arrival time,energy,intensity position,etc.,through the list data The package mode(List-mode)is transmitted to the host computer software,and then analyzed and processed,which can realize data measurement reproduction and digital coincidence and anti-coincidence measurement.