Research On Key Technologies Of Digital Multichannel Spectrometer System

In the fields of nuclear physics research,ray detection and nuclear technology application,nuclear energy spectrum is very important information to be acquired,among which the analysis of multi-channel pulse amplitude is the most core technical means of nuclear energy spectrometer.The main development direction of multichannel spectrometer is the acquisition of nuclear energy signals and digital processing [1].Nowadays,in the era of rapid development of digital signal processing technology,researchers have realized the use of high-speed and high-resolution data acquisition CARDS to collect the incoming nuclear signals,and the use of high-speed digital signal processor to effectively analyze and extract the amplitude of the pulse signal.High-speed acquisition of nuclear energy signals and digital processing are the main development directions of multi-channel spectrometer [1].Many related research institutions at home and abroad on the key technology of digital spectrometer system was studied,and the current foreign digital spectrometer is already realized commercialization,but domestic research and application development is still in the stage,the waveform digitalization,digital wave filter forming keep and pulse amplitude,pulse signal amplitude extraction need further explore [1].In this paper,the dual-channel multi-channel pulse spectrometer system is designed.The system mainly USES the 14-bit AD9643 chip as the Analog to Digital Converter(ADC)module,takes the model XC6SLX45 spartan-6 series FPGA as the pulse counting storage and control module,and STM32F4 as the control circuit and network interface module.The system mainly includes pre-attenuation circuit,peak detection and holding circuit,AD sampling circuit,FPGA processing module,ARM control module,network communication module and LabVIEW upper computer module.The system mainly studied the following key technical problems:(1)through the comparison and analysis of several effective amplitude extraction methods in the multi-channel nuclear spectrometer system,a new amplitude extraction method,namely peak retention extraction method,is proposed.Its characteristics are as follows: simple algorithm,reduced ADC sampling requirements,and reduced hardware cost.In this design,the problem of pulse accumulation with pulse resolution within 300 k Hz is solved by the peak holding circuit.(2)peak extraction is the most critical part of the multi-channel spectrometer pulse analysis and processing system.In this design,FIR pulse filtering and quadratic polynomial five-point fitting smoothing method are carried out through FPGA software to reduce the noise,and the final peak value is obtained after the average sum of data is obtained.Due to the continuity of nuclear pulse data,this design solves the problem of peak extraction of multiple signals by combining hardware and software.(3)data transmission and display are also key components of the digital nuclear spectrometer system.This design uses FPGA and ARM signal processing and data transmission control,and USES LabVIEW to complete the real-time display and storage of data.The display interface of energy spectrum includes the options of point,line and plane.The display of energy spectrum is clear and easy to observe.