Charged particle identification method and system based on screen grid ionization chamber signal waveform

Abstract

The invention discloses a charged particle identification method and system based on a screen grid ionization chamber signal waveform, and belongs to the technical field of radiation detection. The charged particle identification method comprises the following steps: acquiring a current signal waveform generated by charged particles at an anode of a screen grid ionization chamber and extracting a characteristic quantity; analyzing the relationship between the obtained characteristic quantity and the particle energy and incident angle, and constructing particle identification parameters; according to a relation between particle energy and a range, drawing by using related identification parameters, and determining distribution characteristics of different particles; and identifying different particles according to different distribution characteristics. According to the method, the energy deposition characteristics of the particles are utilized, and the constructed identification parameters weaken the influence of the incident angle of the particles on particle identification, so that the five particles of p, D, T, 3He and 4He can be accurately identified in a relatively large angle range, and the section measurement efficiency is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of radiation detection, and in particular relates to a charged particle identification method and system based on a screen grid ionization chamber signal waveform. Background Art

[0002] With the deepening of particle physics and nuclear physics research, the acquisition of nuclear data has put forward new requirements for the identification technology of charged particles. In nuclear physics experiments, bombardment nuclear reactions are often accompanied by the generation of a large number of particle fragments. In order to study these particle fragments, they must first be identified. 3 He and 4 The identification of charged particles such as He is the basis and key to obtaining charged particle nuclear data. In the measurement of alpha particles and heavy charged particles, the screen grid ionization chamber is a commonly used gas detector with high counting rate, fast time response, good energy resolution, high detection efficiency, and the anode pulse amplitude is independent of the ionization position.

[0003] However, in recent years, although the application of screen grid ionization chambers has become more mature, their effect is still only to distinguish the particles produced by known reactions, and it is still not possible to distinguish the unknown p, D, T, 3 He or 4 Therefore, the measurement efficiency of nuclear cross section is greatly limited. Summary of the invention

[0004] In order to overcome the shortcomings of the prior art, the present invention aims to provide a charged particle identification method and system based on the signal waveform of the screen grid ionization chamber, so as to solve the problem that the prior art cannot identify multiple unknown particles (such as p, D, T, 3 He or 4 He) technical issues for identification.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] The present invention discloses a charged particle identification method based on a screen grid ionization chamber current signal waveform, comprising:

[0007] Obtain the current signal waveform generated by charged particles at the anode of the screen grid ionization chamber and extract the characteristic quantity;

[0008] constructing particle identification parameters using the characteristic quantity;

[0009] Plot and characterize the distribution of different particles based on identification parameters;

[0010] Charged particles are identified based on the distribution characteristics of different particles.

[0011] Preferably, the characteristic quantities include the total integral of the anode current signal, the average slope of the rising edge of the anode current signal, the integral area when the anode current signal reaches a peak, the drift time of electrons from the cathode to the gate, and the starting time difference between the cathode and anode current signals.

[0012] Preferably, using the characteristic quantity to construct particle identification parameters includes:

[0013] Construct the identification parameter Q, which is the total charge deposited by the particle, obtained by calculating the total integral of the anode current signal, reflecting the energy of the incident particle;

[0014] The identification parameter k(t-Δt) / S is constructed to eliminate the influence of the angle and is regarded as only related to the particle range R; where k is the average slope of the rising edge of the anode current signal, t is the drift time of the electron from the cathode to the gate, Δt is the starting time difference between the cathode and anode current signals, and S is the integrated area when the anode current signal reaches its peak.

[0015] The calculation formula of t is:

[0016]

[0017] Where D is the distance from cathode to gate, v C is the drift velocity of electrons in the cathode and anode regions.

[0018] When the electric field strength, gas composition and pressure inside the detector are determined, v c It can be regarded as a constant. The experimental measurement method is: set a particle source parallel to the gate between the cathode and the gate, and measure the time difference between each incident particle generating a signal at the cathode and the anode, then v C It can be obtained by the following formula:

[0019]

[0020] Where D r is the vertical distance from the particle source to the gate, T2 is the time when the anode current signal starts, T1 is the time when the cathode current signal starts, i represents the i-th particle, and n is the total number of particles. In addition, it can also be obtained by querying the relevant database.

[0021] In addition, as an alternative, the characteristic quantity (t-Δt) can also be expressed as the anode current signal rise time t rise instead, especially when the projection of the particle range in the direction normal to the detector is smaller than the distance from the grid to the anode.

[0022] Further preferably, mapping and determining the distribution characteristics of different particles according to the identification parameters includes:

[0023] The k(t-Δt) / SQ diagram is plotted, which reflects the relationship between particle energy and range. The distribution of different particles shows different bands.

[0024] More preferably, charged particles are identified based on the distribution characteristics of different particles, including: fitting different bands preferably using a quadratic polynomial (other functions may also be selected depending on the situation), and translating the fitted curve as a dividing line for distinguishing different particles.

[0025] More preferably, for unknown incident particles, identification parameters Q and k(t-Δt) / S are calculated through their signal waveforms and reflected in a k(t-Δt) / SQ diagram, and the type of particle is determined by the area where the point falls.

[0026] The present invention also discloses a charged particle identification system based on a screen grid ionization chamber signal waveform, which implements the above-mentioned charged particle identification method based on a screen grid ionization chamber signal waveform, including:

[0027] A feature extraction module is used to analyze and generate feature quantities based on the signal waveform generated by charged particles at the anode of the screen grid ionization chamber;

[0028] A particle identification parameter construction module is used to construct particle identification parameters according to characteristic quantities;

[0029] A drawing module, used to draw images based on the identification parameters and determine the distribution characteristics of different particles;

[0030] The charged particle recognition module is used to identify different particles based on their distribution characteristics in the image.

[0031] Preferably, it also includes a signal acquisition module for acquiring signal waveforms generated by charged particles at the cathode and anode of the detector through the screen grid ionization chamber.

[0032] The present invention also discloses a computer device, including a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the above-mentioned charged particle identification method based on the screen grid ionization chamber signal waveform when executing the computer program.

[0033] The present invention also discloses a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the charged particle identification method based on the screen grid ionization chamber signal waveform are implemented.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] The charged particle identification method based on the screen grid ionization chamber disclosed in the present invention is based on the working principle of the screen grid ionization chamber, by acquiring the signal waveform generated by the charged particles at the anode of the detector and generating a characteristic quantity, constructing the particle identification parameters according to the characteristic quantity, utilizing the energy deposition characteristics of the particles, and the constructed identification parameters weaken the influence of the particle incident angle on the particle identification, so that p, D, T, 3 He, 4 Therefore, the present invention can observe the distribution characteristics of different particle events by combining advanced signal processing technology and multi-parameter analysis, so that it can accurately identify p, D, T, 3 He, 4 Since the effective detection area of ​​the screen grid ionization chamber is large, the measurement time of the angular distribution cross section can be greatly shortened, which can effectively improve the measurement accuracy within the limited measurement time. In addition, the gas detector is cheap, which can effectively reduce the cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a schematic diagram of the process of the charged particle identification method of the present invention;

[0037] Figure 2 is the relationship between particle energy E and charge Q;

[0038] Figure 3 is the relationship between the particle incident angle and the slope of the signal rising edge;

[0039] Figure 4 is the distribution of different incident particles in the k(t-Δt) / SQ diagram. DETAILED DESCRIPTION

[0040] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0041] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof 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 necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0042] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0043] See also Figure 1 , is a charged particle identification method based on a screen grid ionization chamber signal waveform, comprising the following steps:

[0044] S1: Obtain the signal waveform generated by charged particles at the anode of the screen grid ionization chamber and extract the characteristic quantity;

[0045] S2: Use the obtained characteristic quantities to construct particle identification parameters;

[0046] S3: Draw and determine the distribution characteristics of different particles based on the identification parameters;

[0047] S4: Identify particles based on the distribution characteristics of different particles.

[0048] Preferably, in step S1, the extracted characteristic quantities include: the total integral of the anode current signal, the average slope of the rising edge of the anode current signal, the integrated area when the anode current signal reaches a peak, the drift time of electrons from the cathode to the gate, and the starting time difference between the cathode and anode current signals.

[0049] Preferably, in step S2, the obtained characteristic quantity is used to construct a particle identification parameter, which specifically includes:

[0050] S21: Construct the identification parameter Q, which is the total charge deposited by the particles, reflecting the energy of the incident particles, and can be obtained by integrating the anode current signal.

[0051] S22: Construct the identification parameter k(t-Δt) / S, which eliminates the influence of the angle and can be regarded as only related to the particle range R. Where k is the average slope of the rising edge of the anode current signal, t is the drift time of the electron from the cathode to the gate, Δt is the start time difference between the cathode and anode current signals, and S is the integrated area when the anode current signal reaches the peak.

[0052] Preferably, in step S3, a k(t-Δt) / SQ diagram is drawn, which reflects the relationship between particle energy and range, and different particles have obvious different strip distributions.

[0053] Preferably, in step S4, the method for identifying different particles includes: preferably using a quadratic polynomial (other functions may also be selected according to circumstances) to fit different bands as a dividing line for distinguishing different particles.

[0054] In one embodiment of the present invention, a charged particle identification method based on a screen grid ionization chamber signal waveform is provided, which specifically includes:

[0055] S1: Obtain the signal waveform generated by the charged particles at the anode of the screen grid ionization chamber and extract the characteristic quantity. The waveform reflects the Bragg peak of the incident particles, that is, the energy deposition characteristics at the end of the particle track. Different particles have different Bragg peaks, so extracting the characteristic quantity related to them can achieve the effect of identifying different particles. The characteristic quantities include: the total integral Q of the anode current signal, the average slope k of the rising edge of the anode current signal, the integral area S when the anode current signal reaches the peak, the drift time t of the electron from the cathode to the grid, and the starting time difference Δt of the cathode and anode current signals. The obtained characteristic quantity is related to the incident particles and the design parameters of the detector.

[0056] S2: Use the obtained characteristic quantity to construct the particle identification parameters. Q reflects the total charge deposited by the charged particle in the detector and is proportional to the energy of the particle, such as Figure 2 As shown; k has nothing to do with the energy of the incident particle, but only with the angle, which is proportional to 1 / cosθ, as Figure 3 As shown, θ is the angle between the particle incident direction and the detector normal direction; S is used to represent k0 when the particle is incident vertically. Since the rising edge of the signal is only related to the Bragg peak of the particle, S can be approximately regarded as not changing with the particle energy and angle, and only related to the type of incident particles; t and Δt are the drift time of electrons from the cathode to the gate, and the time difference between the start of the cathode and anode current signals, which can be expressed as:

[0057]

[0058] Where D is the distance from cathode to gate, v C is the drift velocity of electrons in the cathode and anode regions, and R is the particle range.

[0059] When the electric field strength, gas composition and pressure inside the detector are determined, v c It can be regarded as a constant. The experimental measurement method is: set a particle source parallel to the gate between the cathode and the gate, and measure the time difference between each incident particle generating a signal at the cathode and the anode, then v C It can be obtained by the following formula:

[0060]

[0061] Where D r is the vertical distance from the particle source to the gate, T2 is the time when the anode current signal starts, T1 is the time when the cathode current signal starts, i represents the i-th particle, and n is the total number of particles. In addition, it can also be obtained by querying the relevant database.

[0062] From equations (1.1) and (1.3), we can know that:

[0063]

[0064] The electron drift rate is fixed, so (t-Δt) is only related to the projection distance Rcosθ of the particle incident track. In addition, as an alternative, the characteristic quantity (t-Δt) can also be used as the anode current signal rise time t rise instead, especially when the projection of the particle range in the direction normal to the detector is smaller than the distance from the grid to the anode.

[0065] By constructing the identification parameter k(t-Δt) / S, the influence of the particle incident angle is eliminated, so that the parameter is only related to the particle range.

[0066] S3: Draw a graph based on the identification parameters and determine the distribution characteristics of different particles. The relationship between the energy and range of different particles is different. The identification parameter Q obtained in S2 is only related to the particle energy; k(t-Δt) / S is only related to the particle range. Draw a k(t-Δt) / SQ graph for all incident particles. Depending on the type of particle, the corresponding points should be distributed near different curves, such as Figure 4 As shown, since the energy deposition of particles is a random process, the distribution of different particles shows different bands.

[0067] S4: Identify particles according to the distribution characteristics of different particles. It is preferred to use quadratic polynomial fitting for different particle strips, and translate the resulting curve as the dividing line of different particles. For unknown incident particles, the above identification parameters are calculated through their signal waveforms and reflected in the k(t-Δt) / SQ diagram. The type of particle can be determined by the area where the point falls. In this embodiment, when the incident angle is within the range of 45° and different particles are incident at the same time, the p, D, T, 3 He, 4 The accuracy rates of He recognition are 82.26%, 53.60%, 49.23%, 76.08% and 73.81% respectively.

[0068] In another embodiment, the present invention also provides a charged particle identification system based on a screen grid ionization chamber, which can implement the above-mentioned charged particle identification method, including:

[0069] A signal acquisition module, used to collect the signal waveform generated by charged particles at the cathode and anode of the detector through the screen grid ionization chamber;

[0070] A feature extraction module is used to analyze and generate feature quantities based on the signals collected by the signal collection module;

[0071] A particle identification parameter construction module is used to construct particle identification parameters according to characteristic quantities;

[0072] A drawing module is used to draw images based on the identification parameters and observe the distribution characteristics of different particle events;

[0073] The particle identification module is used to identify different particles according to the distribution characteristics of different particle events in the image.

[0074] In one embodiment of the present invention, a computer device is provided, which includes a processor and a memory, wherein the memory is used to store a computer program, wherein the computer program includes program instructions, and the processor implements the steps of the above-mentioned charged particle identification method when executing the computer program. The processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, etc., which are the computing core and control core of the terminal, which are suitable for implementing one or more instructions, and are specifically suitable for loading and executing one or more instructions in a computer storage medium to implement the corresponding method flow or corresponding functions; the processor described in the embodiment of the present invention can be used to implement the steps of the above-mentioned charged particle identification method when the processor executes the computer program.

[0075] In another embodiment of the present invention, the present invention further provides a storage medium, specifically a computer-readable storage medium, which is a memory device in a computer device for storing programs and data. When the computer program in this embodiment is executed by a processor, the steps of the above-mentioned charged particle identification method are implemented. It can be understood that the computer-readable storage medium here can include both built-in storage media in the computer device and, of course, extended storage media supported by the computer device. The computer-readable storage medium provides a storage space, which stores the operating system of the terminal. In addition, one or more instructions suitable for being loaded and executed by the processor are also stored in the storage space, and these instructions can be one or more computer programs (including program codes). It should be noted that the computer-readable storage medium here can be a high-speed RAM memory or a non-volatile memory, such as at least one disk memory. The processor can load and execute one or more instructions stored in the computer-readable storage medium to implement the corresponding steps of the steps of the charged particle identification method in the above-mentioned embodiment.

[0076] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0077] The present invention is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products of the embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of the processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0078] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0079] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0080] In summary, the method disclosed in the present invention utilizes the energy deposition characteristics of particles, and the recognition parameters constructed reduce the influence of the particle incident angle on particle identification, so that p, D, T, 3 He, 4 The five kinds of particles improve the efficiency of cross-section measurement.

[0081] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A charged particle identification method based on a screen grid ionization chamber current signal waveform, characterized in that: include: Obtain the current signal waveform generated by charged particles at the anode of the screen grid ionization chamber and extract the characteristic quantity; constructing particle identification parameters using the characteristic quantity; Plot and characterize the distribution of different particles based on identification parameters; Charged particles are identified based on the distribution characteristics of different particles.

2. The charged particle identification method based on the screen grid ionization chamber current signal waveform according to claim 1 is characterized in that: The characteristic quantities include the total integral of the anode current signal, the average slope of the rising edge of the anode current signal, the integral area when the anode current signal reaches a peak, the drift time of electrons from the cathode to the gate, and the starting time difference between the cathode and anode current signals.

3. The charged particle identification method based on the screen grid ionization chamber current signal waveform according to claim 1 is characterized in that: The particle identification parameters are constructed using the characteristic quantity, including: Construct the identification parameter Q, which is the total charge deposited by the particle, obtained by calculating the total integral of the anode current signal, reflecting the energy of the incident particle; Construct the identification parameter k(t-Δt) / S, which eliminates the influence of the angle and is regarded as only related to the particle range R; where k is the average slope of the rising edge of the anode current signal, t is the drift time of the electron from the cathode to the gate, Δt is the starting time difference between the cathode and anode current signals, and S is the integrated area when the anode current signal reaches the peak; The calculation formula of t is: Where D is the distance from cathode to gate, v C is the drift velocity of electrons in the cathode and anode regions; When the electric field strength, gas composition and pressure inside the detector are determined, v c As a constant, the experimental measurement method is: set a particle source parallel to the gate between the cathode and the gate, and measure the time difference between each incident particle generating a signal at the cathode and the anode, then v C It is obtained from the following formula: Where D r is the vertical distance from the particle source to the gate, T2 is the time when the anode current signal starts, T1 is the time when the cathode current signal starts, i represents the i-th particle, and n is the total number of particles; In addition, v C It can also be obtained by querying relevant databases; In addition, when the projection distance of the particle range in the normal direction of the detector is smaller than the distance from the gate to the anode, the characteristic quantity (t-Δt) can be expressed as the anode current signal rise time t rise replace.

4. The charged particle identification method based on the screen grid ionization chamber signal waveform according to claim 3 is characterized in that: Plot and characterize the distribution of different particles based on identification parameters, including: The k(t-Δt) / SQ diagram is plotted, which reflects the relationship between particle energy and range. The distribution of different particles shows different bands.

5. The charged particle identification method based on the screen grid ionization chamber signal waveform according to claim 4 is characterized in that: The charged particles are identified according to the distribution characteristics of different particles, including: fitting different bands with a quadratic polynomial and translating the fitted curve as a dividing line for distinguishing different particles.

6. The charged particle identification method based on the screen grid ionization chamber signal waveform according to claim 5, characterized in that: For unknown incident particles, the identification parameters Q and k(t-Δt) / S are calculated from their signal waveform and reflected in the k(t-Δt) / SQ diagram. The type of particle is determined by the area where the point falls.

7. A charged particle identification system based on a screen grid ionization chamber signal waveform, characterized in that: The method for identifying charged particles based on a screen grid ionization chamber signal waveform as described in any one of claims 1 to 6 comprises: A feature extraction module is used to analyze and generate feature quantities based on the signal waveform generated by charged particles at the anode of the screen grid ionization chamber; A particle identification parameter construction module is used to construct particle identification parameters according to characteristic quantities; A drawing module, used to draw images based on the identification parameters and determine the distribution characteristics of different particles; The charged particle recognition module is used to identify different particles based on their distribution characteristics in the image.

8. The charged particle identification system based on the screen grid ionization chamber signal waveform according to claim 7, characterized in that: It also includes a signal acquisition module, which is used to collect signal waveforms generated by charged particles at the cathode and anode of the detector through the screen grid ionization chamber.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the charged particle identification method based on the screen grid ionization chamber signal waveform described in any one of claims 1 to 6 are implemented.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the steps of the charged particle identification method based on the screen grid ionization chamber signal waveform described in any one of claims 1 to 6 are implemented.

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