Nuclear pulse signal processing system adopting analog-digital double shaping
Through analog digital double forming technology, combined with Gaussian forming and digital ladder forming, the problem of insufficient energy spectrum measurement accuracy and anti-interference ability under complex radiation background is solved, and high-precision energy spectrum measurement and strong anti-interference ability are achieved.
Patent Information
- Application Number
- CN202411748108.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-02
- Publication Date
- 2025-03-14
AI Technical Summary
In the measurement scenarios of complex radiation backgrounds and environmental noise, it is difficult to achieve high-precision energy spectrum measurement, with low measurement accuracy and poor anti-interference ability.
A nuclear pulse signal processing system with analog digital double forming is adopted, combined with analog Gaussian forming and digital ladder forming technology, and high-precision processing of nuclear pulse signals is achieved through analog digital synchronous forming structure and particle identification structure.
It improves the accuracy and anti-interference ability of energy spectrum measurement, and can couple multiple types of detectors in complex radiation scenarios to reduce the interference of environmental noise on the measurement system.
Smart Images
Figure CN119620151A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of digital signals, and in particular to a nuclear pulse signal processing system using analog digital dual shaping. Background Art
[0002] Energy spectrum measurement is an important method for nuclear radiation detection and is widely used in environmental radiation monitoring, medical diagnosis, industrial imaging and other fields. It is an important measurement method for obtaining information about the types, abundance, reaction mechanisms and material composition of radioactive nuclides. Therefore, how to achieve high-precision energy spectrum measurement and obtain accurate energy spectrum measurement results has become a research focus in the field of nuclear radiation measurement.
[0003] Multi-Channel Analyzer (MCA) is an important part of the energy spectrum measurement system, which directly affects the accuracy of the energy spectrum measurement results. Its function is to collect the nuclear pulse signal output by the detector and analyze and process it. There are mainly two types, one is the analog multi-channel pulse amplitude analyzer (AMCA) using a filter shaping circuit, and the other is the digital multi-channel pulse amplitude analyzer (DMCA) using a digital filter shaping algorithm. According to the characteristics of the two MCAs, better energy spectrum measurement can be achieved when the measurement parameters are relatively simple, the types of detectors to be tested are limited, and the measurement environment noise is relatively simple. However, with the development of nuclear energy utilization, in measurement scenarios with complex radiation backgrounds and environmental noise such as fusion reactors, fission reactors, and nuclear facility decommissioning, a single MCA is difficult to match various detectors, resulting in limited energy spectrum measurement accuracy. Therefore, it is necessary to design an energy spectrum measurement system that can achieve high-precision measurement in the above scenarios.
[0004] The SK filter is an analog Gaussian shaping circuit that shapes the nuclear pulse signal into a Gaussian-like signal. It has the characteristics of fast shaping speed and good anti-noise performance. With the development of microelectronics technology, digital trapezoidal shaping based on large-scale field-programmable gate arrays (FPGA) has the characteristics of high precision, strong flexibility, and strong anti-interference ability. Therefore, the energy spectrum measurement system using analog Gaussian and digital trapezoidal synchronous shaping structure can achieve high-precision energy spectrum measurement in different measurement scenarios. Summary of the invention
[0005] The purpose of the present invention is to provide a nuclear pulse signal processing system using analog digital dual forming, which solves the technical problems of low measurement accuracy and poor anti-interference ability in the prior art, and achieves the technical effect of improving measurement accuracy and enhancing anti-interference ability.
[0006] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is:
[0007] A nuclear pulse signal processing system using analog digital dual shaping includes an analog digital synchronous shaping structure and a particle discrimination structure. The analog digital synchronous shaping structure includes a digital shaping channel and an analog shaping channel. The digital shaping channel includes a high-speed ADC and an FPGA. The analog shaping channel includes an SK shaping circuit. The analog shaping channel uses the SK shaping circuit to shape the pulse signal into a Gaussian-like signal, realizes analog particle discrimination and amplitude extraction based on the Gaussian-like signal, and transmits the data to the FPGA to output a discrimination spectrum and an analog shaping spectrum. The digital shaping channel can perform Gaussian deconvolution processing on the Gaussian-like signal, and then use digital trapezoidal shaping to output a spectrum line diagram. It can also directly perform digital trapezoidal shaping on the nuclear pulse signal output by the probe, and realize digital particle discrimination based on the trapezoidal signal.
[0008] As an improvement, the analog-digital synchronous shaping structure can obtain spectrum data after the nuclear pulse signal passes through, and the spectrum data will be transmitted to the host computer to draw the analog shaping and digital shaping energy spectra; the analog shaping channel takes the SK shaping circuit as the core, and shapes the nuclear pulse signal into a Gaussian-like signal; the digital shaping channel takes FPGA as the core, uses high-speed ADC to collect nuclear pulse signals, and realizes digital trapezoidal shaping in FPGA.
[0009] As an improvement, the host computer issues a synchronous shaping instruction, and after the FPGA outputs a synchronous shaping selection signal, it controls the selection switch to synchronously input the nuclear pulse signal into the analog shaping channel and the digital shaping channel. The synchronous shaping structure synchronously performs analog and digital filtering and shaping processing on the nuclear pulse signal, and outputs analog shaping spectra and digital shaping spectra.
[0010] As an improvement, the Gaussian deconvolution trapezoidal shaping can collect the signal after Gaussian analog shaping to the FPGA through the ADC, and obtain a nuclear pulse signal with a high signal-to-noise ratio according to the deconvolution algorithm, and then implement a smaller width digital fast trapezoidal shaping on the nuclear pulse signal.
[0011] As an improvement, the specific algorithm used in the Gaussian deconvolution trapezoidal shaping is: dg(n)=a*(g(n)-g(n-1)-g(n-2L)+g(n-2L-1)), which is implemented in the FPGA using shift register, adder, and subtractor modules, where g(n) is a Gaussian-like shaped signal obtained by ADC acquisition. The signal needs to be differentiated twice, and the simulated Gaussian shaping parameter is inverted by controlling the shift register parameter L to obtain the Gaussian deconvolution signal dg(n).
[0012] As an improvement, the Gaussian deconvolution signal dg(n) needs to further control the shift register parameters K and MK, that is, the rise time and the flat top time of the trapezoidal shaping, so as to realize fast trapezoidal shaping of the pile-up pulse signal.
[0013] As an improvement, the particle identification will receive the corresponding analog Gaussian shaped signal. After the signal differentiation processing, the peak time of the Gaussian shaped signal can be extracted and the signal zero crossing point can be obtained. The particle identification structure will judge the type of the particle based on the set threshold and the zero crossing point, and transmit the identification data to the FPGA through the ADC to draw the identification spectrum and calculate the analog identification factor.
[0014] As an improvement, the particle identification can be performed by setting long and short integration gates to obtain the ratio of fast and slow components of the forming signal, and the type of the particle can be determined based on the set ratio threshold. Similarly, a digital identification spectrum and a digital identification factor can be obtained.
[0015] The beneficial effects of the present invention are as follows: by configuring the analog and digital synchronous forming structure, the problems of a single transmission energy spectrum measurement forming method and poor flexibility are avoided, and the overall measurement accuracy is improved; by equipping it with Gaussian deconvolution trapezoidal forming, the problems of easy pile-up of transmission Gaussian forming and poor anti-noise ability of trapezoidal forming are avoided, and the overall anti-interference ability is improved; by equipping it with a particle identification structure, the overall anti-interference performance can be further improved, and the pile-up effect can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Figure 1 The overall block diagram of a nuclear pulse signal processing system using analog digital dual shaping according to the present invention;
[0017] Figure 2 This is a block diagram of the analog digital synchronous shaping structure of a nuclear pulse signal processing system using analog digital dual shaping according to the present invention;
[0018] Figure 3 The digital trapezoidal shaping structure of the analog Gaussian shaping deconvolution of the nuclear pulse signal processing system using analog digital dual shaping of the present invention;
[0019] Figure 4 This is a block diagram of the algorithm content of a nuclear pulse signal processing system using analog digital dual shaping according to the present invention;
[0020] Figure 5 The invention discloses a novel particle discrimination structure based on analog shaping and digital shaping of a nuclear pulse signal processing system using analog and digital dual shaping. DETAILED DESCRIPTION
[0021] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.
[0022] It should be noted that the terms "first" and "second" in this application are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Thus, the features defined as "first" and "second" can explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally also includes steps or units that are not listed, or optionally also includes other steps or units inherent to these processes, methods, products or devices.
[0023] like Figure 1 As shown in the figure, the nuclear pulse signal output by the probe is controlled by the selection switch to enter the analog shaping channel and the digital shaping channel individually or synchronously. The analog shaping channel uses the SK shaping circuit to shape the nuclear pulse signal into a Gaussian-like signal, realizes analog particle identification and amplitude extraction based on the Gaussian-like signal, and transmits the data to the FPGA to output the identification spectrum and the analog shaping energy spectrum. The digital shaping channel can perform deconvolution processing on the analog shaped Gaussian-like signal, and then use digital trapezoidal shaping to output the spectrum line diagram; it can also directly perform digital trapezoidal shaping on the nuclear pulse signal output by the probe, and realize digital particle identification based on the trapezoidal signal.
[0024] like Figure 2 As shown, when used, the analog digital synchronous shaping structure obtains energy spectrum data, and finally transmits the energy spectrum data to the host computer to draw analog shaping and digital shaping energy spectra. The analog shaping channel takes the SK shaping circuit as the core, and shapes the nuclear pulse signal into a Gaussian-like signal. The digital shaping channel takes FPGA as the core, uses a high-speed ADC to collect nuclear pulse signals, and implements digital trapezoidal shaping in FPGA. The host computer issues a synchronous shaping instruction, and the FPGA outputs a synchronous shaping selection signal to control the selection switch so that the nuclear pulse signal is synchronously input into the analog shaping channel and the digital shaping channel. The synchronous shaping structure synchronously performs analog and digital filtering shaping processing on the nuclear pulse signal, outputs analog shaping spectrum lines and digital shaping spectrum lines, and can couple various types of detectors in complex radiation scenes to reduce the interference of complex environmental noise on the measurement system.
[0025] The analog shaping channel uses SK shaping circuit to filter out most of the noise of the original nuclear pulse signal, outputs shaping parameter adjustment signal through FPGA, and controls analog switch to realize numerically controlled multi-parameter quasi-Gaussian shaping, which can filter out the noise of the original nuclear pulse signal to a certain extent, suppress ballistic loss and pulse accumulation events, and use analog to digital converter (ADC) to digitally discretize the quasi-Gaussian signal, enter FPGA for amplitude extraction and output analog shaping spectrum data. The digital shaping channel uses high-speed and high-resolution ADC to collect the signal-conditioned nuclear pulse signal to FPGA, trigger the nuclear pulse signal through constant ratio timing algorithm in FPGA, and then realize digital trapezoidal shaping of nuclear pulse signal through trapezoidal shaping algorithm, finally extract the amplitude and output digital shaping spectrum data to the host computer, and compare the energy resolution and count rate of analog shaping spectrum and digital shaping spectrum in the host computer, and select the shaping method in this measurement scenario.
[0026] like Figure 3 and Figure 4 As shown, when used, the SK shaping circuit usually selects a larger shaping width to improve the noise and ballistic loss suppression capability, which makes the circuit less effective in separating piled pulses; the digital trapezoidal algorithm is prone to baseline drift and has poor noise resistance. Therefore, the present invention proposes a digital trapezoidal shaping algorithm that simulates Gaussian shaping deconvolution; the signal after Gaussian simulation shaping is collected to FPGA through ADC, and a nuclear pulse signal with a high signal-to-noise ratio is obtained according to the deconvolution algorithm, and then a digital fast trapezoidal shaping of a smaller width is implemented on the nuclear pulse signal.
[0027] The algorithm is implemented in FPGA using shift registers, adders, subtractors and other modules. The algorithm block diagram is shown in the figure. Figure 4 As shown. Among them, g(n) is the Gaussian-like shaped signal acquired by ADC. After the signal is differentiated twice, the analog Gaussian shaping parameter is inverted by controlling the shift register parameter L to obtain the Gaussian deconvolution signal dg(n). Since the analog Gaussian shaping can filter out most of the noise of the original nuclear pulse signal, dg(n) has a higher signal-to-noise ratio. By controlling the shift register parameters K and MK, that is, the rise time and flat top time of the trapezoidal shaping, the accumulated nuclear pulse signal can be fast-trapezoidal shaped, thereby improving the energy resolution and counting rate of the energy spectrum measurement system.
[0028] like Figure 5As shown in the figure, when the traditional particle identification algorithm performs particle identification, the nuclear pulse signal will superimpose a part of the electronic noise, which will affect its identification effect. Therefore, the patent of this invention proposes a new particle identification structure based on analog shaping and digital shaping. That is, the original nuclear pulse signal is first subjected to analog Gaussian shaping and digital trapezoidal shaping. Due to the differences in the physical properties of the interaction between different particles and the detector, the nuclear pulse signal output by the detector has different fall times. After analog Gaussian shaping and digital trapezoidal shaping, a shaped signal with different peak time can be obtained, and particle identification is achieved according to the characteristics of the shaped signal.
[0029] Among them, for analog Gaussian shaping signals, after signal differentiation processing, its peak time can be extracted, and the signal zero crossing point can be obtained. The type of particle can be judged by comparing the set threshold with the zero crossing point, and the discrimination data can be transmitted to FPGA through ADC to draw the discrimination spectrum and calculate the analog discrimination factor; for digital trapezoidal shaping signals, the ratio of fast and slow components of the shaping signal can be obtained by setting long and short integration gates, and the type of particle can be judged according to the set ratio threshold. Similarly, the digital discrimination spectrum and digital discrimination factor can be obtained. In FPGA, the discrimination gating signal is sent out by the analog discrimination factor and the digital discrimination factor to select the discrimination structure with better discrimination effect.
[0030] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.
Claims
1. A nuclear pulse signal processing system using analog digital dual shaping, characterized in that: The invention comprises an analog digital synchronous shaping structure and a particle discrimination structure, wherein the analog digital synchronous shaping structure comprises a digital shaping channel and an analog shaping channel, wherein the digital shaping channel comprises a high-speed ADC and an FPGA, and the analog shaping channel comprises an SK shaping circuit. The analog shaping channel uses the SK shaping circuit to shape the pulse signal into a Gaussian-like signal, realizes analog particle discrimination and amplitude extraction based on the Gaussian-like signal, and transmits the data to the FPGA to output a discrimination spectrum and an analog shaping spectrum. The digital shaping channel can perform Gaussian deconvolution processing on the Gaussian-like signal, and then use digital trapezoidal shaping to output a spectrum line diagram, and can also directly perform digital trapezoidal shaping on the nuclear pulse signal output by the probe, and realize digital particle discrimination based on the trapezoidal signal.
2. A nuclear pulse signal processing system using analog digital dual shaping according to claim 1, characterized in that: The analog digital synchronous shaping structure can obtain spectrum data after the nuclear pulse signal passes through, and the spectrum data will be transmitted to the host computer to draw the analog shaping and digital shaping energy spectrum; wherein the analog shaping channel takes the SK shaping circuit as the core, and shapes the nuclear pulse signal into a Gaussian-like signal; The digital shaping channel is based on FPGA, uses high-speed ADC to collect nuclear pulse signals, and implements digital trapezoidal shaping in FPGA.
3. A nuclear pulse signal processing system using analog digital dual shaping according to claim 2, characterized in that: The host computer sends out a synchronous shaping instruction, and after the FPGA outputs a synchronous shaping selection signal, it controls the selection switch to synchronously input the nuclear pulse signal into the analog shaping channel and the digital shaping channel. The synchronous shaping structure synchronously performs analog and digital filtering and shaping processing on the nuclear pulse signal, and outputs analog shaping spectrum lines and digital shaping spectrum lines.
4. A nuclear pulse signal processing system using analog digital dual shaping according to claim 1, characterized in that: The Gaussian deconvolution trapezoidal shaping can collect the signal after Gaussian simulation shaping to FPGA through ADC, and obtain a nuclear pulse signal with a high signal-to-noise ratio according to the deconvolution algorithm, and then implement a digital fast trapezoidal shaping of a smaller width on the nuclear pulse signal.
5. A nuclear pulse signal processing system using analog digital dual shaping according to claim 4, characterized in that: The specific algorithm used in the Gaussian deconvolution trapezoidal shaping is: dg(n)=a*(g(n)-g(n-1)-g(n-2L)+g(n-2L-1)). The algorithm is implemented in FPGA using shift register, adder, and subtractor modules, wherein g(n) is a Gaussian-like shaping signal obtained by ADC acquisition. The signal needs to be differentiated twice, and then the simulated Gaussian shaping parameter is inverted by controlling the shift register parameter L to obtain the Gaussian deconvolution signal dg(n).
6. A nuclear pulse signal processing system using analog digital dual shaping according to claim 5, characterized in that: The Gaussian deconvolution signal dg(n) needs to further control the shift register parameters K and MK, that is, the rise time and the flat top time of the trapezoidal shaping, so as to realize fast trapezoidal shaping of the pile-up pulse signal.
7. A nuclear pulse signal processing system using analog digital dual shaping according to claim 1, characterized in that: The particle identification will receive the corresponding analog Gaussian shaped signal. After the signal differentiation processing, the peak time of the Gaussian shaped signal can be extracted and the signal zero crossing point can be obtained. The particle identification structure will judge the type of the particle based on the set threshold and the zero crossing point, and transmit the identification data to the FPGA through the ADC to draw the identification spectrum and calculate the analog identification factor.
8. A nuclear pulse signal processing system using analog digital dual shaping according to claim 7, characterized in that: The particle identification can be performed by setting long and short integration gates to obtain the ratio of the fast and slow components of the forming signal, and the type of the particle can be determined according to the set ratio threshold. Similarly, a digital identification spectrum and a digital identification factor can be obtained.