Nuclear pulse amplitude extraction method based on parameter identification and nuclear pulse analysis system

Abstract

The invention belongs to the technical field of digital signal processing, and particularly provides a nuclear pulse amplitude extraction method based on parameter identification and a nuclear pulse analysis system, which are used for solving the problem that the precision of an energy spectrum diagram is reduced due to baseline drift of a nuclear pulse signal and pulse accumulation and discarding, so that the energy resolution and the counting rate of the nuclear pulse energy spectrum diagram are improved. According to the method, accurate capture and processing of nuclear pulse signals can be realized, an original sampling sequence signal is processed by using a filtering method, the influence of baseline drift is reduced, parameter identification and amplitude extraction are carried out on stacked pulses processed by a combined filtering method by using a parameter identification model, and a high-precision spectrogram is generated; therefore, the energy resolution and the counting rate of the system are improved, and powerful technical support is provided for the fields of nuclear physics research, nuclear energy application, nuclear radiation detection and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of digital signal processing, and specifically provides a nuclear pulse amplitude extraction method based on parameter identification and a digital multi-channel pulse analysis system. Background Art

[0002] In the fields of nuclear physics research, nuclear energy application and nuclear radiation detection, accurate analysis and processing of nuclear pulse signals are crucial; nuclear pulse signals contain rich nuclear reaction information, and by accurately capturing, analyzing and processing these signals, important parameters of the nuclear reaction process, such as energy distribution, reaction type, etc., can be obtained; therefore, the development of efficient and accurate nuclear pulse analysis systems has always been a research hotspot in this field.

[0003] The digital filtering shaping method of nuclear signals is the key technology of the digital nuclear energy spectrum measurement system. Previously, in the process of spectrum measurement, the spectral accuracy is often affected by pulse pile-up, ballistic loss, baseline drift and noise, which are particularly serious under high counting rate conditions. At present, some nuclear pulse analysis systems have been proposed, but most of these systems have problems of low energy resolution and poor counting rate. Therefore, the development of a high-resolution and high-counting-rate nuclear pulse digital multi-channel pulse analysis system is of great significance for promoting the development of nuclear physics research, nuclear energy application and nuclear radiation detection. Summary of the invention

[0004] The purpose of the present invention is to provide a nuclear pulse amplitude extraction method based on parameter identification and a digital multi-channel pulse analysis system, so as to solve the problem of decreased accuracy of energy spectrum caused by baseline drift and pulse pile-up abandonment of nuclear pulse signals, thereby improving the energy resolution and counting rate of nuclear pulse energy spectrum. The present invention can realize accurate capture and processing of nuclear pulse signals, firstly use filtering method to process the original sampling sequence signal to reduce the influence of baseline drift, and then use parameter identification model to perform parameter identification and extract amplitude of pile-up pulses processed by joint filtering method, generate high-precision spectrum, thereby improving the energy resolution and counting rate of the system, and providing strong technical support for the fields of nuclear physics research, nuclear energy application and nuclear radiation detection.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] A method for extracting nuclear pulse amplitude based on parameter identification, characterized in that it comprises the following steps:

[0007] Step 1. Collect the electrical signal of the digital nuclear energy spectrum measurement system and obtain the negative exponential decay pulse signal through the preamplifier circuit.

[0009] Step 2. Negative exponential decay pulse signal Use filtering method to estimate the baseline and get the baseline value And based on the baseline value After drift correction is completed, a negative exponential decay signal V is obtained. i (t);

[0010] Step 3. Set the filter time parameter t a With t b , the negative exponential decay signal V is transformed into i (t) is converted into a triangular pulse signal V o1 (t) and the trapezoidal pulse signal V o2 (t);

[0011] Step 4. Search for the triangular pulse signal V o1 For all triangle peak moments in (t), for any triangle peak moment t o1max , corresponding to the triangular pulse peak value V o1 (t o1max ), half-height amplitude of the falling edge of the triangular pulse V o1 (t o1max +(n b -n a ) / 2), and at the same time, the trapezoidal pulse peak value V o2 (t o1max ), trapezoidal pulse central amplitude V o2 (t o1max +(n b -n a ) / 2);

[0012] Step 5. Establish the pile-up judgment condition, any triangle peak time t o1max If the accumulation judgment condition is met, the negative exponential decay signal V i (t) is the pile-up pulse signal. The amplitude coefficient A of the pile-up pulse signal is obtained by the parameter identification model. i ; Otherwise, obtain the trapezoidal pulse peak value V o2 (t o1max ) as the trapezoidal pulse amplitude;

[0013] Step 6. Generate a nuclear pulse energy spectrum according to the amplitude coefficients of all the extracted trapezoidal pulse amplitudes and the pile-up pulse signal, and complete the nuclear pulse signal amplitude extraction.

[0014] Furthermore, in step 1, the negative exponential decay pulse signal Specifically expressed as:

[0015]

[0016] Where t represents a discrete time variable, i represents the sequence number of the nuclear pulse signal, represents the negative exponential decay pulse signal at time t, w(t) represents the noise signal at time t, u(t) represents the unit step signal, A i represents the amplitude coefficient of the ith nuclear pulse signal, T i represents the time when the i-th nuclear pulse signal appears, τ represents the attenuation coefficient, and N represents the total number of nuclear pulse signals.

[0017] Furthermore, in step 2, the baseline value Specifically expressed as:

[0018]

[0019] Among them, B i represents the i-th baseline sampling value, and They represent the i-th and i-1-th baseline values ​​after filtering, and k represents the weight calculation factor.

[0020] Furthermore, in step 2, the drift correction is specifically expressed as:

[0021]

[0022] Among them, V i (t) represents the negative exponential decay pulse signal after drift correction.

[0023] Furthermore, in step 3, the triangular pulse signal V o1 (t) is expressed as:

[0024]

[0025] in, n c =2*n a , τ is the attenuation coefficient, T s Indicates the sampling period.

[0026] Furthermore, in step 3, the trapezoidal pulse signal V o2 (t) is expressed as:

[0027]

[0028] in, n d =n a +n b , τ is the attenuation coefficient, T s Indicates the sampling period.

[0029] Furthermore, in step 5, the parameter identification model identifies the amplitude coefficient A of the pile-up pulse signal iThe specific process is: send the pile-up pulse signal into the parameter identification model to obtain the attenuation coefficient τ and amplitude coefficient A of the pile-up pulse signal i and the time of appearance T i , and generate the parameters (attenuation coefficient τ, amplitude coefficient A i and the time of appearance T i ) to obtain a trapezoidal pulse signal Calculating Trapezoidal Pulse Amplitude With trapezoidal pulse amplitude V o2 (t o1max ), when the absolute value of the difference E is less than the preset threshold, the identification ends and the corresponding amplitude coefficient A is output i ; Otherwise, continue iterating.

[0030] Furthermore, in step 5, the stacking judgment condition is to satisfy any of the following conditions:

[0031] The first judgment condition: V o1 (t o1max )≠2*V o1 (t o1max +(n b -n a ) / 2),

[0032] The first judgment condition: V o2 (t o1max )≠V o2 (t o1max +(n b -n a ) / 2).

[0033] Based on the above-mentioned nuclear pulse shaping amplitude extraction method based on parameter identification, the present invention also provides a digital multi-channel pulse analysis system, and the digital multi-channel pulse analysis system for processing nuclear pulse signals includes:

[0034] A digital baseline estimation module is used to implement filtering and drift correction, estimate the baseline through filtering, and perform drift correction on the negative exponential decay signal according to the baseline value;

[0035] A digital filter shaping module is used to establish a dual-channel joint filter shaping method, which converts the negative exponential decay signal after drift correction into a triangular pulse signal and a trapezoidal pulse signal;

[0036] The pulse amplitude extraction module is used to search for the peak time of the triangular pulse signal and extract the amplitude parameter accordingly;

[0037] A pulse accumulation judgment module is used to establish accumulation judgment conditions and judge the accumulation pulse signal according to the amplitude parameter;

[0038] A pulse pile-up parameter identification module is used to establish a parameter identification model and obtain the amplitude coefficient of the pile-up pulse signal through the parameter identification model;

[0039] The digital energy spectrum generation module is used to generate a nuclear pulse energy spectrum according to the amplitude of the trapezoidal pulse and the amplitude coefficient of the pile-up pulse signal.

[0040] Based on the above technical solution, the beneficial effects of the present invention are:

[0041] The present invention provides a method for extracting the amplitude of a nuclear pulse signal based on parameter identification and a nuclear pulse analysis system. First, a baseline is estimated by using a filtering method on a sampling signal to complete drift correction; then, a joint filtering shaping method is established to determine the generation time of a pulse and the generation of pulse pile-up, and to extract the effective pulse amplitude of a normal nuclear pulse signal without pile-up; finally, the piled-up pulse is decomposed and parameters are extracted through a parameter identification model to obtain more effective pulse amplitudes; in summary, the present invention solves the problem of decreased energy spectrum accuracy caused by baseline drift and pulse pile-up abandonment of nuclear pulse signals, and improves the energy resolution and counting rate of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 The figure is a flow chart of a method for extracting the amplitude of a nuclear pulse signal provided in an embodiment of the present invention.

[0043] Figure 2 It is a structural schematic diagram of a digital multi-channel pulse analysis system provided in an embodiment of the present invention.

[0044] Figure 3 A schematic diagram of baseline correction provided in an embodiment of the present invention.

[0045] Figure 4 It is a principle diagram of trapezoidal filtering and triangular filtering provided in an embodiment of the present invention.

[0046] Figure 5 Schematic diagram of trapezoidal filtering and triangular filtering provided in an embodiment of the present invention.

[0047] Figure 6 This is a parameter identification principle diagram provided in an embodiment of the present invention.

[0048] Figure 7 A comparison diagram of nuclear pulse energy spectra generated by a nuclear pulse signal amplitude extraction method based on parameter identification and a trapezoidal filtering method provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0049] In order to make the purpose, technical solutions and beneficial effects of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments; it should be understood that the embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0050] This embodiment provides a method for extracting the amplitude of a nuclear pulse signal based on parameter identification, and the process is as follows: Figure 1 As shown, the specific steps include:

[0051] Step 1. Collect the probe electrical signal of the digital nuclear spectrum measurement system and obtain the negative exponential decay pulse signal through the preamplifier circuit. Specifically expressed as:

[0052]

[0053] Where t represents a discrete time variable, i represents the sequence number of the nuclear pulse signal, represents the negative exponential decay pulse signal at time t, w(t) represents the noise signal at time t, u(t) represents the unit step signal, A i represents the amplitude coefficient of the ith nuclear pulse signal, T i represents the time when the i-th nuclear pulse signal appears, τ represents the attenuation coefficient, and N represents the total number of nuclear pulse signals;

[0054] Step 2. Negative exponential decay pulse signal Use filtering method to estimate the baseline and get the baseline value And based on the baseline value For negative exponential decay pulse signal Complete drift correction;

[0055] The baseline value Specifically expressed as:

[0056]

[0057] Among them, B i represents the i-th baseline sampling value, and They represent the i-th and i-1-th baseline values ​​after filtering, respectively, and k represents the weight calculation factor;

[0058] The drift correction is expressed as:

[0059]

[0060] Among them, V i (t) represents the negative exponential decay pulse signal after drift correction;

[0061] Step 3. Set the filter time parameter t a With t b , the negative exponential decay signal V is transformed into i (t) is converted into a triangular pulse signal V o1 (t) and the trapezoidal pulse signal Vo2 (t);

[0062] The triangular pulse signal V o1 (t) is expressed as:

[0063]

[0064] in, n c =2*n a , τ is the attenuation coefficient, T s Indicates the sampling period;

[0065] The trapezoidal pulse signal V o2 (t) is expressed as:

[0066]

[0067] in, n d =n a +n b , τ is the attenuation coefficient, T s Indicates the sampling period;

[0068] Step 4. Search for the triangular pulse signal V o1 For all triangle peak moments in (t), for any triangle peak moment t o1max , corresponding to the triangular pulse peak value V o1 (t o1max ), half-height amplitude of the falling edge of the triangular pulse V o1 (t o1max +(n b -n a ) / 2), and at the same time, the trapezoidal pulse peak value V o2 (t o1max ), trapezoidal pulse central amplitude V o2 (t o1max +(n b -n a ) / 2);

[0069] Step 5. Establish the pile-up judgment condition, any triangle peak time t o1max If the accumulation judgment condition is met, the negative exponential decay signal V i (t) is the pile-up pulse signal. The amplitude coefficient A of the pile-up pulse signal is obtained by the parameter identification model. i ; Otherwise, obtain the trapezoidal pulse peak value V o2 (t o1max ) as the trapezoidal pulse amplitude;

[0070] The parameter identification model identifies the amplitude coefficient A of the pile-up pulse signal i The specific process is: the triangular pulse signal V o1 (t), trapezoidal pulse signal V o2 (t) and the corresponding triangle peak time t o1max Enter the parameter identification model to obtain the attenuation coefficient τ and amplitude coefficient A of the pile-up pulse signal i and the time of appearance T i , and generate the parameters (attenuation coefficient τ, amplitude coefficient A i and the time of appearance T i ) to obtain a trapezoidal pulse signal Calculating Trapezoidal Pulse Amplitude With trapezoidal pulse amplitude V o2 (t o1max ), when the absolute value of the difference E is less than the preset threshold, the identification ends and the corresponding amplitude coefficient A is output i ; Otherwise, continue iterating;

[0071] The stacking judgment condition is to satisfy any of the following conditions:

[0072] The first judgment condition: V o1 (t o1max )≠2*V o1 (t o1max +(n b -n a ) / 2)

[0073] The first judgment condition: V o2 (t o1max )≠V o2 (t o1max +(n b -n a ) / 2)

[0074] Step 6. Generate a nuclear pulse energy spectrum according to the amplitude coefficients of all the extracted trapezoidal pulse amplitudes and the pile-up pulse signal, and complete the nuclear pulse signal amplitude extraction.

[0075] At the same time, this embodiment also provides a digital multi-channel pulse analysis system, such as Figure 2 As shown, for implementing the above-mentioned nuclear pulse shaping amplitude extraction method based on parameter identification, the digital multi-channel pulse analysis system includes:

[0076] A digital baseline estimation module is used to implement filtering and drift correction, estimate the baseline through filtering, and perform drift correction on the negative exponential decay signal according to the baseline value;

[0077] A digital filter shaping module is used to establish a dual-channel joint filter shaping method, which converts the negative exponential decay signal after drift correction into a triangular pulse signal and a trapezoidal pulse signal;

[0078] The pulse amplitude extraction module is used to search for the peak time of the triangular pulse signal and extract the amplitude parameter accordingly;

[0079] A pulse accumulation judgment module is used to establish accumulation judgment conditions and judge the accumulation pulse signal according to the amplitude parameter;

[0080] A pulse pile-up parameter identification module is used to establish a parameter identification model and obtain the amplitude coefficient of the pile-up pulse signal through the parameter identification model;

[0081] The digital energy spectrum generation module is used to generate a nuclear pulse energy spectrum according to the amplitude of the trapezoidal pulse and the amplitude coefficient of the pile-up pulse signal.

[0082] The embodiment is further described below in conjunction with a simulation test of a digital nuclear energy spectrum measurement system.

[0083] The simulation signal used in this embodiment is a pulse sequence generated based on the Monte Carlo method, and its energy spectrum is consistent with the actual instrument measurement result. It is used as the input signal of the simulation test to verify the good effect of the present invention in processing pulse pileup. The specific steps are as follows:

[0084] Step 1. Generate a negative exponential decay pulse signal with a known amplitude based on Monte Carlo simulation, and send it to the digital multi-channel pulse analysis system as an input signal, such as Figure 2 As shown;

[0085] Step 2: Use filtering method to estimate the baseline of the sampled signal, and the weight calculation factor k = 3, such as Figure 3 As shown, baseline correction is completed;

[0086] Step 3. Set the time parameter t for trapezoidal formation a =10T s ,t b =20T s , the time parameter t of triangle forming a =10T s ,t b =20T s , the pulse signal is jointly filtered and shaped to complete the signal conversion, such as Figure 4 , Figure 5 As shown, Figure 4 (a) is the principle diagram of ladder filtering. Figure 4 (b) The triangle filter principle diagram. Figure 5 Schematic diagram of trapezoidal filtering and triangle filtering;

[0087] Step 4. Search for the triangular pulse signal V o1 For all triangle peak moments in (t), for any triangle peak moment t o1max , corresponding to the triangular pulse peak value V o1 (t o1max ), half-height amplitude of the falling edge of the triangular pulse V o1 (t o1max +(n b -n a ) / 2), and at the same time, the trapezoidal pulse peak value V o2 (t o1max ), trapezoidal pulse central amplitude V o2 (t o1max +(n b -n a ) / 2);

[0088] Step 5. Compare the amplitude at each peak moment to determine the accumulation situation. If there is no accumulation, obtain the trapezoidal pulse peak value V o2 (t o1max ), when there is accumulation, the accumulation pulse is sent to the parameter identification model, and the threshold is set to the trapezoidal pulse peak value V o2 (t o1max ) is 5%, and the amplitude coefficient of pile-up pulse separation is obtained, such as Figure 6 The figure shows the principle diagram of parameter identification;

[0089] Step 6. Generate a nuclear pulse energy spectrum according to the amplitudes of all the extracted trapezoidal pulses and the amplitudes of the piled-up pulse signals, such as Figure 7 The figure shows a comparison of nuclear pulse energy spectra generated by the nuclear pulse signal amplitude extraction method based on parameter identification and the trapezoidal filtering method. It can be seen from the figure that the nuclear pulse signal amplitude extraction method based on parameter identification in the present invention effectively improves the count value of the spectrum, which is helpful for subsequent energy spectrum analysis.

[0090] The above description is only a specific implementation mode of the present invention. Any feature disclosed in this specification, unless otherwise stated, can be replaced by other alternative features that are equivalent or have similar purposes; all the disclosed features, or all the steps in the methods or processes, except for mutually exclusive features and / or steps, can be combined in any way.

Claims

1. A method for extracting nuclear pulse amplitude based on parameter identification, characterized in that: The following steps are involved: Step 1. Collect the electrical signal of the digital nuclear energy spectrum measurement system and obtain the negative exponential decay pulse signal through the preamplifier circuit. Step 2. Negative exponential decay pulse signal Use filtering method to estimate the baseline and get the baseline value And according to the baseline value After drift correction is completed, a negative exponential decay signal V is obtained. i (t); Step 3. Set the filter time parameter t a With t b , the negative exponential decay signal V is transformed into i (t) is converted into a triangular pulse signal V o1 (t) and the trapezoidal pulse signal V o2 (t); Step 4. Search for the triangular pulse signal V o1 For all triangle peak moments in (t), for any triangle peak moment t o1max , corresponding to the triangular pulse peak value V o1 (t o1max ), half-height amplitude of the falling edge of the triangular pulse V o1 (t o1max +(n b -n a ) / 2), and at the same time, the trapezoidal pulse peak value V o2 (t o1max ), trapezoidal pulse central amplitude V o2 (t o1max +(n b -n a ) / 2); Step 5. Establish the pile-up judgment condition, any triangle peak time t o1max If the accumulation judgment condition is met, the negative exponential decay signal V i (t) is the pile-up pulse signal. The amplitude coefficient A of the pile-up pulse signal is obtained by the parameter identification model. i ; Otherwise, obtain the trapezoidal pulse peak value V o2 (t o1max ) as the trapezoidal pulse amplitude; Step 6. Generate a nuclear pulse energy spectrum according to the amplitude coefficients of all the extracted trapezoidal pulse amplitudes and the pile-up pulse signal, and complete the nuclear pulse signal amplitude extraction.

2. The method for extracting nuclear pulse amplitude based on parameter identification according to claim 1, characterized in that: In step 1, the negative exponential decay pulse signal Specifically expressed as: Where t represents a discrete time variable, i represents the sequence number of the nuclear pulse signal, represents the negative exponential decay pulse signal at time t, w(t) represents the noise signal at time t, u(t) represents the unit step signal, A i represents the amplitude coefficient of the ith nuclear pulse signal, T i represents the time when the i-th nuclear pulse signal appears, τ represents the attenuation coefficient, and N represents the total number of nuclear pulse signals.

3. The method for extracting nuclear pulse amplitude based on parameter identification according to claim 1, characterized in that: In step 2, the baseline value Specifically expressed as: Among them, B i represents the i-th baseline sampling value, and They represent the i-th and i-1-th baseline values ​​after filtering, and k represents the weight calculation factor.

4. The method for extracting nuclear pulse amplitude based on parameter identification according to claim 1, characterized in that: In step 2, the drift correction is specifically expressed as: Among them, V i (t) represents the negative exponential decay pulse signal after drift correction.

5. The method for extracting nuclear pulse amplitude based on parameter identification according to claim 1, characterized in that: In step 3, the triangular pulse signal V o1 (t) is expressed as: in, n c =2*n a , τ is the attenuation coefficient, T s Indicates the sampling period.

6. The method for extracting nuclear pulse amplitude based on parameter identification according to claim 1, characterized in that: In step 3, the trapezoidal pulse signal V o2 (t) is expressed as: in, n d =n a +n b , τ is the attenuation coefficient, T s Indicates the sampling period.

7. The method for extracting nuclear pulse amplitude based on parameter identification according to claim 1, characterized in that: In step 5, the parameter identification model identifies the amplitude coefficient A of the pile-up pulse signal i The specific process is: send the pile-up pulse signal into the parameter identification model to obtain the attenuation coefficient τ and amplitude coefficient A of the pile-up pulse signal i and the time of appearance T i , and generate the parameters (attenuation coefficient τ, amplitude coefficient A i and the time of appearance T i ) to obtain a trapezoidal pulse signal Calculating Trapezoidal Pulse Amplitude With trapezoidal pulse amplitude V o2 (t o1max ), when the absolute value of the difference E is less than the preset threshold, the identification ends and the corresponding amplitude coefficient A is output i ; Otherwise, continue iterating.

8. The method for extracting nuclear pulse amplitude based on parameter identification according to claim 1, characterized in that: In step 5, the accumulation judgment condition is to meet any of the following conditions: The first judgment condition: V o1 (t o1max )≠2*V o1 (t o1max +(n b -n a ) / 2), The first judgment condition: V o2 (t o1max )≠V o2 (t o1max +(n b -n a ) / 2).

9. A digital multi-channel pulse analysis system, characterized in that: The digital multi-channel pulse analysis system is used to execute the nuclear pulse amplitude extraction method based on parameter identification according to claim 1, specifically comprising: A digital baseline estimation module is used to implement filtering and drift correction, estimate the baseline through filtering, and perform drift correction on the negative exponential decay signal according to the baseline value; A digital filter shaping module is used to establish a dual-channel joint filter shaping method, which converts the negative exponential decay signal after drift correction into a triangular pulse signal and a trapezoidal pulse signal; The pulse amplitude extraction module is used to search for the peak time of the triangular pulse signal and extract the amplitude parameter accordingly; A pulse accumulation judgment module is used to establish accumulation judgment conditions and judge the accumulation pulse signal according to the amplitude parameter; A pulse pile-up parameter identification module is used to establish a parameter identification model and obtain the amplitude coefficient of the pile-up pulse signal through the parameter identification model; The digital energy spectrum generation module is used to generate a nuclear pulse energy spectrum according to the amplitude of the trapezoidal pulse and the amplitude coefficient of the pile-up pulse signal.

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