Digital spike-plateau dual-channel shaping method and system for processing nuclear pulse signals

Abstract

The application belongs to the technical field of signal processing, and discloses a digital peak-plateau double-channel shaping method and system for processing nuclear pulse signals, wherein the correlation between peak pulse shaping and plateau pulse shaping results is analyzed, and a peak-plateau double-channel shaping method is established; the severity of pulse pile-up is judged by using the peak pulse shaping channel, whether the pulse is reserved is judged, and the position of the pulse is determined; the peak value signal is provided by using the plateau shaping channel, and the pulse amplitude is extracted. The digital pulse amplitude analyzer adopting the peak-plateau double-channel shaping algorithm can identify and reserve the effective pulse amplitude in the pulse pile-up, so that the resolution of the nuclear energy spectrum is improved. The peak-plateau double-channel shaping method can effectively solve the problem of pulse pile-up in the nuclear energy spectrum measurement system, and greatly improves the count rate in the nuclear energy spectrum measurement. The application also has the advantages of high resolution, good shaping linearity and the like.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of signal processing, and particularly relates to a digital peak-flat double-channel shaping method and system for processing nuclear pulse signals. BACKGROUND

[0002] At present, compared with the traditional analog filter shaping algorithm, the digital nuclear pulse filter shaping algorithm has many advantages, and has become the mainstream of signal processing. A simple and efficient digital nuclear pulse shaping algorithm can not only reduce the influence of electronic noise, ballistic deficit and pulse pile-up on energy and time resolution, but also can optimize the selection of energy resolution and count rate, and improve the flexibility and adaptability of the system.

[0003] Peak shaping is an important method for nuclear pulse signal filter shaping. According to the optimal filter shaping theory of nuclear pulse signal, the sharp pulse is the most ideal pulse, which can theoretically achieve the best signal-to-noise ratio. However, the infinitely long sharp pulse cannot be realized in reality, so researchers at home and abroad have carried out research on the shaping algorithm of the finite length sharp pulse. At the beginning, the convolution method was used to obtain the sharp pulse response function to obtain the sharp pulse shaping algorithm. Since the convolution operation is large and the process is complex, it is not easy to implement. Later, the function recursion method was developed to derive the sharp pulse shaping algorithm. Compared with the ladder shaping algorithm, this algorithm has better filter noise reduction effect, and the accuracy of pulse amplitude extraction is improved to a certain extent. However, it still cannot solve the influence of pulse pile-up. In the system with low count rate requirement, discarding these pile-up pulses can effectively avoid the error amplitude extraction and has little effect on the subsequent energy spectrum analysis. However, in the energy spectrum measurement system with high count rate requirement, the probability of pulse pile-up also increases. If the pile-up pulses are still discarded completely, the accuracy of the energy spectrum will be greatly reduced, which seriously affects the subsequent energy spectrum analysis.

[0004] Through the above analysis, the problems and defects of the prior art are:

[0005] (1) The traditional method of obtaining the sharp pulse response function by convolution to obtain the sharp pulse shaping algorithm has a large convolution operation and a complex process, which is not easy to implement.

[0006] (2) The traditional method of deriving the sharp pulse shaping algorithm by time domain difference still cannot solve the influence of pulse pile-up.

[0007] (3) In the energy spectrum measurement system with high count rate requirement, the probability of pulse pile-up increases. If the pile-up pulses are still discarded completely, the accuracy of the energy spectrum will be greatly reduced, which seriously affects the subsequent energy spectrum analysis. SUMMARY

[0008] In view of the problems in the prior art, the present application provides a digital peak-flat double-channel shaping method and system for processing nuclear pulse signals, aiming at solving the problem of reduced nuclear pulse energy spectrum resolution caused by the pulse pile-up in the existing digital filtering shaping method.

[0009] The present application is implemented as a digital peak-flat double-channel shaping method for processing nuclear pulse signals, which comprises: establishing a peak-flat double-channel shaping method by analyzing the correlation between peak pulse shaping and flat pulse shaping results derived from an algorithm; using the peak pulse shaping channel to determine the severity of pulse pile-up, judge whether the pulse is retained, and determine the position of the pulse generation; using the flat shaping channel to provide a peak signal and extract the pulse amplitude.

[0010] Further, the digital peak-flat double-channel shaping method for processing nuclear pulse signals comprises the following steps:

[0011] Step one, collecting the single exponential decay pulse signal of the electric signal of the probe of the digital nuclear energy spectrum measurement system after the preamplifier;

[0012] Step two, setting the rise time N and flat time D of the peak-flat double-channel shaping method, and using the peak pulse shaping method to convert the single exponential decay signal into a peak pulse signal V o1 ;

[0013] Step three, using the flat shaping method to convert the single exponential decay signal into a flat pulse signal V o2 , searching for all peak values V o1 in the peak pulse signal V o1_max and the corresponding peak time k o1_max ;

[0014] Step four, for each peak time k o1_max , judging whether V o1 (k o1_max +D) is greater than V o1_max / 2; if yes, discard; otherwise, extract the flat pulse peak value V o2 (k o2 +D / 2) in the flat pulse signal V o1_max ;

[0015] Step five, generating a nuclear pulse energy spectrum diagram according to all the extracted flat pulse peak values.

[0016] Further, the single exponential decay pulse signal in step one is: V i (k)=A·e -k / τ• u(k), where A is the exponential signal amplitude, τ is the decay time constant, u(k) is the step function, and k is the discrete time variable;

[0017] Further, in the step two, the rising time N and the flat top time D satisfy the relationship: N = 2D.

[0018] The time-domain recursive difference equation of the peak pulse shaping is as follows:

[0019] δ[k] = s[k] - d - s[k - 1];

[0020] p[k] = (δ[k] - δ[k - N] + δ[k - N - 1] - δ[k - 2N - 1]) - N - (δ[k - N] - δ[k - N - 1] + δ[k - N] - δ[k - N - 1]);

[0021] q[k] = q[k - 1] + p[k];

[0022] r[k] = r[k - 1] + q[k];

[0023] y[k] = y[k - 1] + r[k];

[0024] where d = e -(Ts / τ) , τ is the decay coefficient, Ts is the sampling period, k is the discrete time variable, δ[k] is the current impulse signal, p[k] is the pulse sequence signal, q[k] is the symmetric T-shaped signal sequence, r[k] is the bipolar sawtooth signal sequence, and y[k] is the peak signal sequence.

[0025] Further, in the step three, the time-domain recursive difference equation of the flat top pulse shaping is as follows:

[0026] δ[k] = s[k] - d - s[k - 1];

[0027] p[k] = (δ[k] - δ[k - N] + δ[k - N - D - 1] - δ[k - 2N - D - 1]) - N - (δ[k - N] - δ[k - N - 1] + δ[k - N - D] - δ[k

[0028] -N - D - 1]);

[0029] q[k] = q[k - 1] + p[k];

[0030] r[k] = r[k - 1] + q[k];

[0031] y[k] = y[k - 1] + r[k];

[0032] where d = e -(Ts / τ), tau is an attenuation coefficient, Ts is a sampling period, k is a discrete time variable, delta[k] is a current impulse signal, p[k] is a pulse sequence signal, q[k] is a symmetrical T-shaped signal sequence, r[k] is a bipolar sawtooth signal sequence, and y[k] is a flat-top signal sequence.

[0033] Another object of the present application is to provide a digital peak-flat dual-channel shaping system for processing nuclear pulse signals, which applies the digital peak-flat dual-channel shaping method for processing nuclear pulse signals.

[0034] The shaping method establishing module is configured to establish the peak-flat dual-channel shaping method by analyzing the correlation between the peak pulse shaping and the flat pulse shaping result derived from the algorithm.

[0035] The pulse generation position determining module is configured to determine whether the pulse is reserved and the generation position of the pulse by using the peak pulse shaping channel to determine the severity of the pulse pile-up.

[0036] The pulse amplitude extracting module is configured to extract the pulse amplitude by using the flat shaping channel to provide the peak signal.

[0037] Another object of the present application is to provide a computer device, which comprises a memory and a processor, the memory stores a computer program, and the computer program is executed by the processor to make the processor execute the steps of the digital peak-flat dual-channel shaping method for processing nuclear pulse signals.

[0038] Another object of the present application is to provide a computer readable storage medium, which stores a computer program, and the computer program is executed by a processor to make the processor execute the steps of the digital peak-flat dual-channel shaping method for processing nuclear pulse signals.

[0039] Another object of the present application is to provide an information data processing terminal, which is used to implement the digital peak-flat dual-channel shaping system for processing nuclear pulse signals.

[0040] In combination with the above technical solutions and the technical problems solved, the technical solution of the present application has the following advantages and positive effects:

[0041] The present application relates to a digital filtering shaping method in a digital nuclear energy spectrum measurement system, and provides a digital peak-flat dual-channel shaping method for processing nuclear pulse signals, so as to better solve the pulse pile-up problem.

[0042] The present application provides a nuclear pulse signal digital peak-flat dual-channel shaping method, which establishes a peak-flat dual-channel shaping method by analyzing the correlation between the peak pulse shaping and the flat pulse shaping derived algorithm; the peak pulse shaping channel is used to determine the severity of pulse pile-up, to determine whether the pulse is retained, and to determine the position of the pulse; the flat shaping channel is responsible for providing a peak signal for extracting an accurate and stable pulse amplitude. Through the peak-flat dual-channel shaping method of the present application, the problem of pulse pile-up in the nuclear energy spectrum measurement system can be effectively solved, and the count rate in the nuclear energy spectrum measurement is greatly improved.

[0043] The present application analyzes the peak pulse shaping algorithm and the influence of its parameters on the pulse waveform, and proposes a peak-flat dual-channel shaping analysis method. Compared with the existing peak pulse shaping method, the present application uses a dual-channel shaping method, which has the advantages of high resolution and good shaping linearity.

[0044] Through simulation experiments, it is found that the spectrum obtained by the peak-flat dual-channel shaping analysis method of the present application has more accurate counts than the spectrum obtained by completely discarding pulse pile-up, and is more accurate than the spectrum obtained by completely retaining pulse pile-up, i.e. the highest energy spectrum resolution, which proves the effectiveness of the present application.

[0045] The technical solution of the present application fills the technical gap in the industry at home and abroad: in the method of processing nuclear pulse signals, the peak pulse shaping and the flat pulse shaping are innovatively combined together through a dual-channel method, which combines the advantages of peak pulse shaping in signal positioning and the advantages of flat pulse shaping in signal extraction, can more effectively perform pile-up rejection, and thus meets the requirements of high count rate in nuclear energy spectrum analysis. BRIEF DESCRIPTION OF DRAWINGS

[0046] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiments of the present application will be briefly introduced as follows. Obviously, the drawings described below are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0047] Figure 1This is a flowchart of the digital spike-flat-top dual-channel shaping method for processing nuclear pulse signals provided in an embodiment of the present invention;

[0048] Figure 2 This is a schematic diagram of the digital spike-flat-top dual-channel shaping method for processing nuclear pulse signals provided in this embodiment of the invention;

[0049] Figure 3 These are waveform diagrams of two forming methods provided in embodiments of the present invention;

[0050] Figure 4 This is a partial schematic diagram of the positioning of spike pulse shaping provided in an embodiment of the present invention;

[0051] Figure 5 This is a comparison diagram of the nuclear pulse energy spectrum of the embodiment of the present invention, which uses this stacking rejection method and completely discards the stacking pulse and completely retains the stacking pulse. Detailed Implementation

[0052] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0053] To address the problems existing in the prior art, the present invention provides a digital spike-flat-top dual-channel shaping method and system for processing nuclear pulse signals. The present invention will be described in detail below with reference to the accompanying drawings.

[0054] To enable those skilled in the art to fully understand how the present invention is specifically implemented, this section provides an explanatory description of the embodiments that expand upon the technical solutions of the claims.

[0055] like Figure 1 As shown, the digital spike-flat-top dual-channel shaping method for processing nuclear pulse signals provided in this embodiment of the invention includes the following steps:

[0056] S101, By analyzing the correlation between the results of spike pulse forming and the flat-top pulse forming of the derived algorithm, a spike-flat-top dual-channel forming method is established;

[0057] S102, using the spike pulse shaping channel to determine the severity of pulse accumulation, whether the pulse should be retained, and to determine the location where the pulse is generated;

[0058] S103 utilizes a flat-top forming channel to provide a peak signal, extracting accurate and stable pulse amplitude.

[0059] As a preferred embodiment, such as Figure 2 As shown, the digital spike-flat-top dual-channel shaping method for processing nuclear pulse signals provided in this embodiment of the invention specifically includes the following steps:

[0060] Step 1: Collecting the single exponential decay pulse signal of the electrical signal of the probe of the digital nuclear energy spectrum measurement system after the preamplifier: V i (k) = A·e -k / τ ·u(k), where A is the amplitude of the exponential signal, τ is the decay time constant, u(k) is the step function, and k is the discrete time variable;

[0061] Step 2: Setting the rise time N and the flat top time D of the peak-flat top double-channel shaping method, and the relationship between the rise time N and the flat top time D satisfies: N = 2D;

[0062] Step 3: Using the peak pulse shaping method to convert the single exponential decay signal into a peak pulse signal V o1 , the conversion formula is as follows:

[0063] δ[k] = s[k] - d·s[k-1]

[0064] p[k] = (δ[k] - δ[k-N] + δ[k-N-1] - δ[k-2N-1])

[0065] -N·(δ[k-N] - δ[k-N-1] + δ[k-N] - δ[k-N-1])

[0066] q[k] = q[k-1] + p[k]

[0067] r[k] = r[k-1] + q[k]

[0068] y[k] = y[k-1] + r[k]

[0069] where d = e -(Ts / τ) , τ is the decay coefficient, Ts is the sampling period, and k is the discrete time variable;

[0070] δ[k] is the current impulse pulse signal;

[0071] p[k] is the pulse sequence signal;

[0072] q[k] is the symmetric T-shaped signal sequence;

[0073] r[k] is the bipolar sawtooth signal sequence;

[0074] y[k] is the peak signal sequence.

[0075] Step 4: Using the flat top shaping method to convert the single exponential decay signal into a flat top pulse signal V o2 , the conversion formula is as follows:

[0076] δ[k] = s[k] - d·s[k-1]

[0077] p[k] = (delta[k] - delta[k-N] + delta[k-N-D-1] - delta[k-2N-D-1])

[0078] -N·(delta[k-N] - delta[k-N-1] + delta[k-N-D] - delta[k-N-D-1])

[0079] q[k] = q[k-1] + p[k]

[0080] r[k] = r[k-1] + q[k]

[0081] y[k] = y[k-1] + r[k]

[0082] wherein d = e -(Ts / τ) , tau is an attenuation coefficient, Ts is a sampling period, and k is a discrete time variable;

[0083] delta[k] is a current impulse signal;

[0084] p[k] is a pulse sequence signal;

[0085] q[k] is a symmetric T-shaped signal sequence;

[0086] r[k] is a bipolar sawtooth signal sequence;

[0087] y[k] is a flat-topped signal sequence.

[0088] Step 5: search for all peak values V o1 in the spike pulse signal V o1_max and the peak time k o1_max corresponding thereto;

[0089] Step 6: for each peak time k o1_max , determine whether V o1 (k o1_max +D) is greater than V o1_max / 2; if so, discard; otherwise, extract the flat-topped pulse peak value V o2 (k o2 +D / 2) in the flat-topped pulse signal V o1_max .

[0090] Step 7: generate a nuclear pulse spectrum according to all the extracted flat-topped pulse peak values.

[0091] The digital spike-flat dual-channel shaping system for processing a nuclear pulse signal provided by the embodiment of the present application comprises:

[0092] a shaping method establishment module configured to establish a spike-flat dual-channel shaping method by analyzing the correlation between spike pulse shaping and flat-topped pulse shaping results derived from an algorithm;

[0093] A pulse generation position determination module is configured to determine the severity of pulse pile-up by using a spike pulse shaping channel, determine whether the pulse is reserved, and determine the generation position of the pulse.

[0094] A pulse amplitude extraction module is configured to provide a peak signal by using a flat-top shaping channel, and extract the pulse amplitude.

[0095] During the development or use of the embodiments of the present application, some positive effects have been achieved, and the present application indeed has great advantages compared with the prior art, which will be described below in combination with the data and graphs of the test process.

[0096] Based on the digital spike-flat dual-channel shaping method for processing nuclear pulse signals provided by the embodiments of the present application, the following describes the simulation test of the digital nuclear energy spectrum measurement system, and further describes the embodiments.

[0097] The simulation signal used in the embodiments of the present application is a pulse sequence generated based on the Monte Carlo method, and the energy spectrum diagram thereof is consistent with the actual instrument measurement result. This is used as the input signal of the simulation test, and the test result generates a nuclear pulse energy spectrum comparison diagram under the condition of light pulse pile-up, so as to verify that the present application has good effect in processing pulse pile-up, and the specific is:

[0098] Step 1: Generate a negative exponential decay pulse sequence with a determined amplitude based on the Monte Carlo method, and set the severity of pulse pile-up as the input signal of the simulation;

[0099] Step 2: Set the rise and fall time N of the spike-flat dual-channel shaping method to 20, and the flat-top time D to 10;

[0100] Steps 3-4: Finally, the waveform diagram of the spike-flat dual-channel shaping method is as shown in Figure 3 , Figure 3 which is the local waveform diagram of the two shaping methods;

[0101] Step 5: Search for all spike peaks of the spike pulse signal V o1 and the corresponding peak time as shown in Figure 4 ;

[0102] Steps 6-7: Extract the nuclear pulse energy spectrum diagram generated by the flat-top pulse as shown in Figure 5 . Figure 5The middle is the energy spectrum diagram obtained by using the spike-flat double channel shaping method after pulse pile-up rejection, the energy spectrum diagram obtained by completely rejecting pulse pile-up, and the energy spectrum diagram obtained by completely retaining pulse pile-up; it can be seen from the figure that the spectrum obtained by the spike-flat double channel shaping analysis method of the application has more accurate counts than the spectrum obtained by completely rejecting pulse pile-up, and is more accurate than the spectrum obtained by completely retaining pulse pile-up, that is, the energy spectrum resolution is the highest, proving the effectiveness of the application.

[0103] It should be noted that the embodiments of the present application can be realized by hardware, software or a combination of software and hardware. The hardware part can be realized by special logic; the software part can be stored in a memory and executed by a suitable instruction execution system, such as a microprocessor or a specially designed hardware. Those skilled in the art can understand that the above-mentioned devices and methods can be realized by computer executable instructions and / or included in processor control code, such as carrier media, such as magnetic disk, CD or DVD-ROM, programmable memory, such as read-only memory (firmware), or data carrier, such as optical or electronic signal carrier. The device of the present application and its modules can be realized by hardware circuit, such as ultra-large scale integrated circuit or gate array, semiconductor, such as logic chip, transistor, etc., or programmable hardware device, such as field programmable gate array, programmable logic device, etc., can also be realized by software executed by various types of processors, and can also be realized by the combination of the above hardware circuit and software, such as firmware.

[0104] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, any modification, equivalent replacement and improvement within the technical range disclosed by the present application, which is within the spirit and principle of the present application, should be covered within the protection scope of the present application.

Claims

1. A digital spike-plateau dual-channel shaping method for processing a nuclear pulse signal, characterized in that, The digital peak-flat double-channel shaping method for processing nuclear pulse signals comprises the following steps: The digital peak-flat double-channel shaping method for processing nuclear pulse signals comprises the following steps: Step one, collecting the single exponential decay pulse signal of the electric signal of the probe of the digital nuclear energy spectrum measurement system after the preamplifier; Step two, setting the rise-fall time N and the flat time D of the peak-flat double-channel shaping method, and converting the single exponential decay signal into the peak pulse signal Vo1 by using the peak pulse shaping method; Step three, converting the single exponential decay signal into the flat pulse signal Vo2 by using the flat shaping method, searching all peak values Vo1_max and corresponding peak time ko1_max in the peak pulse signal Vo1; Step four, judging whether Vo1(ko1_max+D) is greater than Vo1_max / 2 for each peak time ko1_max; if yes, discarding; otherwise, extracting the flat pulse peak value Vo2(ko1_max+D / 2) in the flat pulse signal Vo2; Step five, generating the nuclear pulse energy spectrum diagram according to all the extracted flat pulse peak values. The single exponential decay pulse signal in the step one is: Vi(k)=A·e-k / τ·u(k).

2. The digital spike-plateau dual-channel shaping method of processing a nuclear pulse signal as claimed in claim 1, wherein, In the step two, the rise-fall time N and the flat time D satisfy the relationship: N=2D.

3. The digital spike-plateau dual-channel shaping method of processing a nuclear pulse signal as claimed in claim 1, wherein, In the step three, the time domain recursive difference equation of the peak pulse shaping is as follows: δ[k]=s[k]-d·s[k-1]; p[k]=(δ[k]-δ[k-N]+δ[k-N-1]-δ[k-2N-1])-N·(δ[k-N]-δ[k-N-1]+δ[k-N]-δ[k-N-1]); q[k]=q[k-1]+p[k]; r[k]=r[k-1]+q[k]; y[k]=y[k-1]+r[k]; Wherein, d=e-(Ts / τ), τ is the decay coefficient, Ts is the sampling period, k is the discrete time variable; δ[k] is the current impulse pulse signal; p[k] is the pulse sequence signal; q[k] is the symmetric T-shaped signal sequence; r[k] is the bipolar sawtooth signal sequence; y[k] is the peak signal sequence.

4. The digital spike-plateau dual-channel shaping method of processing nuclear pulse signals of claim 1, wherein, In the step four, the time domain recursive difference equation of the flat pulse shaping is as follows: δ[k]=s[k]-d·s[k-1]; p[k]=(δ[k]-δ[k-N]+δ[k-N-D-1]-δ[k-2N-D-1])-N·(δ[k-N]-δ[k-N-1]+δ[k-N-D]-δ[k-N-D-1]); q[k]=q[k-1]+p[k]; r[k]=r[k-1]+q[k]; y[k]=y[k-1]+r[k]; Wherein, d=e-(Ts / τ), τ is an attenuation coefficient, Ts is a sampling period, k is a discrete time variable; δ[k] is a current impulse signal; p[k] is a pulse sequence signal; q[k] is a symmetric T-shaped signal sequence; r[k] is a bipolar sawtooth signal sequence; y[k] is a flat-topped signal sequence.

5. A digital spike-flat dual-channel shaping system for processing nuclear pulse signals, which applies the digital spike-flat dual-channel shaping method for processing nuclear pulse signals according to any one of claims 1 to 4, characterized in that, The digital peak-flat dual-channel shaping system for processing the nuclear pulse signal comprises: A shaping method establishment module is configured to establish a peak-flat dual-channel shaping method by analyzing the correlation between the peak pulse shaping and the flat pulse shaping result derived from an algorithm; A pulse generation position determination module is configured to determine whether the pulse is reserved and determine the pulse generation position by using the peak pulse shaping channel to determine the severity of the pulse pile-up; A pulse amplitude extraction module is configured to extract the pulse amplitude by using the flat shaping channel to provide a peak signal.

6. A computer device, comprising: The computer device comprises a memory and a processor, and the memory stores a computer program, and the computer program is executed by the processor to enable the processor to execute the steps of the digital peak-flat dual-channel shaping method for processing the nuclear pulse signal according to any one of claims 1-4. 7.A computer readable storage medium storing a computer program, and the computer program is executed by a processor to enable the processor to execute the steps of the digital peak-flat dual-channel shaping method for processing the nuclear pulse signal according to any one of claims 1-4.

8. An information data processing terminal, characterized by The information data processing terminal is configured to implement the digital peak-flat dual-channel shaping system for processing the nuclear pulse signal according to claim 5.

Images