Realization Of Energy Spectrometer Based On A New Digital Filter Shaping Algorithm

In the early stage of the development of the gamma spectrometer,the way to achieve it mainly used analog circuits.The internal sample-and-hold and low-speed A/D conversion chip were used to obtain the peak value of the exponential nuclear pulse signal.This method needs to be solved by using hardware.Means to resolve issues such as sample hold and baseline drift.With the increasing integration of chips,such as the emergence of high-speed A/D conversion chips,CPLDs,FPGA chips,etc.,it can make up for the previous shortcomings of the gamma spectrometer,such as low accuracy and weak anti-interference ability,which makes digital gamma Energy spectrometers have developed rapidly.For the digital gamma spectrometer,its core design idea is to use a high-precision pre-processing circuit to amplify the weak exponential nuclear pulse signal,and then use a high-speed A/D conversion chip to digitize the exponential nuclear pulse signal.Perform mathematical operations on FPGA,CPLD and other chips,perform corresponding statistics on the exponential nuclear pulses to obtain gamma spectrum data,and finally perform corresponding analysis on the PC software,such as nuclide identification and other operations.For the digital gamma spectrometer,researchers have long focused on digital filter shaping algorithms and real-time processing,spectrum stabilization adjustment algorithms,and energy spectrum processing algorithms.The current nuclear pulse filter forming methods include triangle,trapezoid,and Gauss.Among them,the triangle and trapezoid forming methods have been developed into the current bipolar triangle forming method and bipolar trapezoid forming method,and the Gauss forming method has been developed for the Mexican straw hat wavelet forming.Method,this article is the method used.Compared with other methods,the Mexican straw hat wavelet shaping method is equivalent to other methods,but its baseline deduction is simple,and the degree of ballistic loss can be measured in the continuous domain.Therefore,the design of a new generation of gamma spectrometer Among them,there are quite advantages.In this paper,a Mexican straw hat wavelet forming theory is used,and a new gamma energy spectrometer is designed and implemented with the help of Beijing Zhongke Kunrun Technology Co.,Ltd.R&D platform.Due to the accumulation of nuclear pulses,there is a baseline drift after the digitization of the nuclear pulses.After the secondary differential smoothing,the baseline will always be equal to 0.There is exactly a second differential operation during the formation process of the Mexican straw hat wavelet pulse filtering,which can eliminate the impact of nuclear pulse baseline drift Therefore,this paper chooses the Mexican straw hat wavelet to filter the exponential kernel pulse.In terms of hardware,FPGA has excellent real-time processing performance,so it is selected as the core device of this design to implement the Mexican straw hat wavelet shaping algorithm.In addition,this paper also involves the design of power supply,signal conditioning,white radio follower,high voltage divider and other circuits in terms of hardware.A complete hardware design scheme of the gamma spectrometer is given.After a series of design and analysis,and a series of tests with the help of Beijing Zhongke Kunrun Technology Co.,Ltd.R&D platform,the final results of this paper are as follows:(1)Applying the Mexican straw hat wavelet shaping theory and implementing it on FPGA,real-time processing of exponential kernel pulse filter shaping is realized.(2)A new type of gamma spectrometer equipment was designed and implemented,and relevant performance parameter tests were performed on sodium iodide crystals and blue bromide crystals,which met the relevant requirements.(3)The energy spectrometer is compatible with the new generation gamma spectrum analysis software developed by Beijing Zhongke Kunrun Technology Co.,Ltd.,which can quickly perform gamma spectrum analysis online.