Whole-process physical simulation method and platform for charged particle waveform acquisition system

Abstract

The invention discloses a full-flow physical simulation method and platform for a charged particle waveform acquisition system, which are used for providing a waveform data set of charged particles, and comprises the following steps: performing particle simulation and energy deposition calculation by adopting high-energy physical simulation software Geant4, and outputting energy deposition data including different depth positions; according to the energy deposition data, silicon micro-strip detector simulation software WeightField2 is adopted to carry out carrier generation and transmission simulation, and a detector induction current diagram is output; according to an induction current diagram of the detector, LTSpice software is adopted to simulate the pre-amplification circuit, and a charged particle complete output waveform is output. The invention provides a solution with low cost and high efficiency, so that the particle identification algorithm can be optimized and trained under the support of richer waveform data. The problems of insufficient sample size, high experiment cost and the like in the prior art can be effectively solved, and the accuracy and practicability of charged particle identification are improved.

Description

Technical Field

[0001] The present invention belongs to the field of space environment detection and nuclear physics technology, and in particular relates to a full-process physical simulation method and platform for a charged particle waveform acquisition system. Background Art

[0002] At present, the application of pulse waveform analysis in charged particle identification is in a transition stage from traditional identification based only on waveform amplitude or rise time to comprehensive waveform feature extraction and identification based on neural networks. However, these waveform acquisition methods based on experimental data have significant deficiencies in many aspects:

[0003] High cost of waveform data acquisition and high human, financial and time costs: Existing research generally relies on experimental waveform data, which usually comes from expensive experimental equipment, such as tandem accelerator plasma irradiation sources, vacuum chambers, etc., and requires a large number of high-precision experimental equipment, including detectors with different parameters, low-noise preamplifiers, low-latency main amplifiers, high-sampling-rate fast acquisition equipment, and anti-interference shielded cables. In addition, the experimental operation process is complicated and time-consuming, and usually requires professionals to perform fine debugging and optimization. Moreover, due to the cumbersome process of replacing the source of the tandem accelerator, usually only one or two particles can be collected in one day. The waveform. In order to obtain comprehensive and accurate waveform data, the experiment usually requires repeated operations many times, and each experiment requires a lot of time, manpower and money. In particular, in practical applications, some particle types or particles with specific energy levels are difficult to generate or capture, which further increases the difficulty and cost of the experiment. Therefore, the acquisition of experimental waveform data is not only time-consuming and costly, but also involves a large investment in personnel and equipment, which limits the efficiency and sustainability of the research.

[0004] Limited sample size and narrow coverage: The waveform data in existing studies usually come from a single source and have a small sample size. For example, some studies only used single-energy alpha particle and proton waveforms, and these two charged particles differ greatly in energy and waveform shape, making it difficult to fully support the training of the back-end particle identification algorithm. In fact, with the increase of atomic number, the waveforms produced by the reaction of heavy ions with the detector become more and more similar, especially for isotopes (since the production of isotopes in tandem accelerators is more difficult), and their waveform differences are often very weak, which makes the identification of particles extremely difficult. Due to the limitations of these waveform samples, the particle identification algorithm may have data deviations during the training process and cannot fully represent the response waveform characteristics of different particles under various conditions, thereby affecting the accuracy and robustness of the algorithm. Therefore, in order to optimize the particle identification algorithm, more sufficient and comprehensive waveform data must be collected to cover a wider range of particle types and conditions.

[0005] Interference of experimental conditions on waveform data: Experimental conditions have a significant impact on the acquired waveform data. For example, factors such as noise interference in the laboratory environment (such as whether the vacuum degree of the detector environment is sufficient, and the signal interference of the kilovolt-level high voltage of the tandem accelerator on cables, amplifiers and other equipment) may lead to instability of experimental results or data errors. These environmental factors may have a negative impact on the accuracy of the waveform, and thus affect the effectiveness and reliability of the particle identification algorithm.

[0006] Based on the above defects of the existing technologies such as high cost of waveform data acquisition, high manpower, financial and time costs, limited sample size and narrow coverage, and interference of experimental conditions on waveform data, there is an urgent need for a full-process physical simulation method for charged particle waveform acquisition systems from detectors to electronics. Summary of the invention

[0007] The present invention proposes a full-process physical simulation method and platform from detectors to electronics. Through this method, the present invention can generate a large amount of high-quality waveform data without relying on expensive and time-consuming experimental processes. Compared with traditional methods that rely on experimental data, the present invention provides a low-cost, high-efficiency solution, which enables particle identification algorithms to be optimized and trained with the support of richer waveform data. The waveform data set generated by the simulation platform can effectively overcome the problems of insufficient sample size and high experimental costs in the prior art, thereby improving the accuracy and practicality of charged particle identification, and providing a data set for charged particle identification technology based on pulse waveform analysis.

[0008] In view of this, the present invention proposes a full-process physical simulation method for a charged particle waveform acquisition system, which is used to provide a waveform data set of charged particles, including:

[0009] Step 1) using high energy physics simulation software Geant4 to perform particle simulation and energy deposition calculation, and outputting energy deposition data including different depth positions;

[0010] Step 2) According to the energy deposition data, the silicon microstrip detector simulation software WeightField2 is used to simulate the carrier generation and transmission, and the detector induced current diagram is output;

[0011] Step 3) According to the detector induced current diagram, the preamplifier circuit is simulated using LTSpice software to output the complete output waveform of the charged particles.

[0012] Preferably, the full-process physical simulation includes: ionization process, plasma erosion effect, carrier transport effect, detector induced charge and preamplifier voltage waveform.

[0013] Preferably, the step 1) comprises:

[0014] Step 1-1) Use high energy physics simulation software Geant4 to set the geometric parameters of the detector and related properties of the particle source;

[0015] Step 1-2) Select a physical model to describe the interaction between particles and detectors;

[0016] Step 1-3) performing irradiation simulation of a particle source and counting the energy deposition caused by different particles in the silicon detector;

[0017] Step 1-4) obtains energy deposition data including different depth positions in micrometers and outputs them in CSV format.

[0018] Preferably, the geometric parameters of the detector in step 1-1) include: a nanometer-scale aluminum metallization layer and a micrometer-scale silicon layer; and the relevant properties of the particle source include: the type and energy of the particles to be simulated.

[0019] Preferably, the step 2) comprises:

[0020] Step 2-1) using the silicon microstrip detector simulation software WeightField2 to read the energy deposition data output by the high energy physics simulation software Geant4, and calculating the number of electron-hole pairs generated at each position of the detector;

[0021] Step 2-2) combining the carrier transport effect and the plasma erosion effect to simulate the movement of electron-hole pairs in the silicon detector;

[0022] Step 2-3) Calculate the magnitude and change of the induced current on the two electrodes of the detector and output the detector induced current diagram.

[0023] Preferably, the step 3) comprises:

[0024] According to the detector induced current diagram, the preamplifier circuit model was established using LTSpice software based on resistive input impedance and high gain characteristics;

[0025] By adjusting the circuit parameters, simulating and optimizing the preamplifier circuit model, reducing the distortion introduced by the circuit, the optimized preamplifier circuit is obtained, and the complete output waveform of the charged particle is output.

[0026] Preferably, the circuit parameters include gain and frequency response.

[0027] On the other hand, the present invention provides a full-process physical simulation platform for a charged particle waveform acquisition system, the platform comprising:

[0028] Ionization process simulation module, used to perform particle simulation and energy deposition calculation using high-energy physics simulation software Geant4, and output energy deposition data including different depth positions;

[0029] The carrier generation and transport simulation module is used to simulate the carrier generation and transport based on the energy deposition data using the silicon microstrip detector simulation software WeightField2, and output the detector induced current diagram;

[0030] The charged particle waveform output module is used to simulate the preamplifier circuit using LTSpice software according to the detector induced current diagram and output the complete output waveform of the charged particle.

[0031] Compared with the prior art, the advantages of the present invention are:

[0032] Through this platform, the present invention can generate a large amount of high-quality waveform data without relying on expensive and time-consuming experimental processes. Compared with the traditional method that relies on experimental data, the present invention provides a low-cost, high-efficiency solution, which enables the particle identification algorithm to be optimized and trained with the support of richer waveform data. The waveform data set generated by the simulation platform can effectively overcome the problems of insufficient sample size and high experimental cost in the prior art, thereby improving the accuracy and practicality of charged particle identification.

[0033] Because this application mainly simulates the entire physical process of charged particle waveform acquisition from ion irradiation, detectors to electronics through Geant4 to WeightField2 to LTSpice, it brings the beneficial effects of efficient data generation, low manpower, financial and time costs, wide coverage, freedom from interference from experimental conditions, high scalability, data quality assurance, and data diversity. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a schematic diagram showing that the electron-hole pairs obtained in the ionization process are in the shape of a cone or a cylinder;

[0035] Figure 2 It is a flow chart of the technical solution of the present invention;

[0036] FIG3 is an ionization energy loss diagram obtained by Geant4 software, wherein FIG3(a) is H-2MeV, FIG3(b) is H-2.8MeV, FIG3(c) is He-2.8MeV, and FIG3(d) is He-4.2MeV;

[0037] Figure 4 It is the detector induced current graph output by WeightField2 software;

[0038] Figure 5This is the voltage waveform of the preamplifier output obtained by LTspice software. DETAILED DESCRIPTION

[0039] 1. Principle

[0040] The present invention mainly aims at the charged particle waveform acquisition system from ion irradiation to detector to electronics, realizes the simulation and reproduction of the full-process physical process on the PC side, and obtains the complete output waveform of the detector under different conditions. The complete physical process includes five parts: ionization process, plasma erosion effect, carrier transport effect, detector induced charge, and pre-amplifier voltage waveform.

[0041] Ionization process: During ion irradiation, when charged particles pass through silicon detectors, they transfer energy to electrons in the material, leaving an ionization track behind them. According to the classical atomic model, when incident particles with positive or negative charge pass near target material atoms, the target atoms' extranuclear electrons are attracted or repelled by the Coulomb effect, thereby gaining a certain amount of energy. In this process, the energy loss caused by the inelastic collision between the incident charged particles and the extranuclear electrons of the target material atoms is called ionizing radiation energy loss, also known as ionization energy loss. If the energy gained by the extranuclear electrons is greater than the binding energy with the atomic orbital, they will break away from the bondage of the nucleus and escape to become free electrons, making the atoms positive ions. In actual materials, this ionization process manifests itself as electrons in the valence band gaining energy to enter the conduction band and leaving holes in the valence band, that is, forming electron-hole pairs. The energy required to generate electron-hole pairs in semiconductors is related to the bandgap width of the semiconductor. In silicon, 3.6 eV of energy is required to generate an electron-hole pair.

[0042] Plasma erosion effect: The electron-hole pairs obtained through the ionization process generally present a cone or cylindrical shape, such as Figure 1 As shown, the plasma begins to erode from the outer surface, and the carriers (i.e., electrons and holes) continue to migrate away from the surface until the electric field inside the body is the same as the external electric field. Then the entire plasma disintegrates, and the electrons and holes are no longer restricted and can move freely.

[0043] Charge carrier transport effect: In semiconductor detectors, due to the effect of an external electric field, free electrons and holes migrate inside the material along the direction of the electric field. The electron-hole pairs generated by the ionization process will begin to migrate toward the electrode under the influence of the external electric field, with electrons moving toward the anode (positive electrode) and holes moving toward the cathode (negative electrode). In this process, the migration speed of electrons and holes is affected by the electron mobility and hole mobility of the material. The electron mobility of semiconductor materials such as silicon is usually higher than the hole mobility, so the migration speed of electrons in an electric field is usually faster. In addition, the strength and direction of the electric field have an important influence on the transport path and efficiency of carriers. When the external electric field is strong, carriers will migrate to the electrode faster, but it may also be accompanied by a higher recombination rate, causing some electrons and holes to recombine and lose effective current contribution.

[0044] Detector induced charge and current process: When freely moving electrons and holes reach the electrodes of the detector, they form induced charges on the electrodes. The accumulation of charge produces a current pulse, which represents the detector's response to the incident particle event. The magnitude of the induced current is closely related to the energy and type of the incident particle. The amount of charge generated by electrons and holes during the migration process determines the amplitude of the output signal, which can reflect the energy and nature of the incident particle. In semiconductor detectors, the induced current usually appears as a short pulse signal. The rise and fall time of this signal is closely related to the migration time and recombination time of the carriers and the strength of the applied electric field.

[0045] Preamplifier voltage waveform: Since the pulse waveform output by the semiconductor detector is very fast (ps level) and small (mV level), the existing high-speed acquisition equipment cannot accurately acquire such a signal, so a preamplifier must be used to amplify the waveform. During the preamplifier amplification process, the signal waveform may experience a certain degree of distortion, which is mainly caused by the characteristics of the circuit (such as gain, bandwidth, response time, etc.) and the current output characteristics of the detector. Therefore, when processing high-frequency or ultra-small amplitude signals, this part needs to be taken into account.

[0046] 2. Solution

[0047] This technical solution is a full-process simulation platform for the physical process from ion irradiation, detectors to charged particle waveform collection in electronics. It is mainly simulated by three softwares: Geant4, WeightField2 and LTSpice. The specific technical solution process is as follows Figure 2WeightField2 is a silicon microstrip detector simulation software developed in recent years. It can calculate the plasma erosion effect, carrier transport effect and the induced charge of the two electrodes of the detector, and then cooperate with LTSpice to simulate the preamplifier circuit. However, WF2 can only calculate based on the average energy loss of the smallest ionized particle, so Geant4 is required to first perform physical simulations of different incident particles, silicon detectors, and laboratory environments to obtain accurate energy losses at different locations of the detector.

[0048] The technical solution of the present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0049] Example 1

[0050] Embodiment 1 of the present invention proposes a full-process physical simulation method from detector to electronics, and its workflow can be roughly divided into the following three steps:

[0051] Step 1: Use Geant4 to perform particle simulation and energy deposition calculation

[0052] Geant4 is a high-energy physics simulation software that can perform simulations based on user-set input parameters (such as detector material, geometry, particle source properties, etc.) and output requirements (such as particle energy deposition, emitted particle information, particle motion trajectory, etc.). We use Geant4 to simulate the ion irradiation process in the actual environment and calculate the ionization effect and energy loss inside the detector. The specific steps are as follows:

[0053] 1) Setting the detector geometry, which typically includes a 100-nanometer-thick aluminum metallization layer and a 300-micron-thick silicon layer, as well as the relevant properties of the particle source (such as the type and energy of the particle).

[0054] 2) Select an appropriate physical model to describe the interaction between particles and detectors. In an embodiment 1, the physical model we use is: Electromagnetic-FTFP_BERT.

[0055] 3) Perform irradiation simulation of the particle source and count the energy deposition caused by different particles (such as MeV-level charged ions) in the silicon detector, as shown in Figure 3. Among them, Figure 3 (a) is H-2MeV, Figure 3 (b) is H-2.8MeV, Figure 3 (c) is He-2.8MeV, and Figure 3 (d) is He-4.2MeV.

[0056] 4) The results output by Geant4 will include energy deposition data at different depths in micrometers, and these data will be exported in CSV format for subsequent processing.

[0057] These outputs provide WeightField2 with the required energy deposition information for further carrier simulations.

[0058] Step 2: Use WeightField2 to simulate carrier generation and transport

[0059] WeightField2 is a recently developed silicon microstrip detector simulation software that can simulate the electron-hole pairs generated from the ionization process and track their movement in the silicon detector. It calculates the amount of charge generation at different locations based on the energy deposition data obtained from Geant4, and simulates the movement of these electron-hole pairs, which is affected by carrier transport effects and plasma erosion effects. In this step, the simulation process of WeightField2 is as follows:

[0060] 1) Read the energy deposition data output by Geant4 and calculate the number of electron-hole pairs generated at each position of the detector based on this data.

[0061] 2) Simulate the movement of these electron-hole pairs in the silicon detector, taking into account carrier transport effects (such as carrier mobility and diffusion) and plasma erosion effects (such as charge drift on the detector surface).

[0062] 3) By simulating these effects, WeightField2 can calculate the magnitude and changes of the induced current on the two electrodes of the detector, providing data support for subsequent waveform acquisition, such as Figure 4 .

[0063] 4) The software interface (GUI) of WeightField2 allows for flexible detector parameter settings, and also supports more accurate physical process simulation by modifying the source code to meet specific experimental requirements.

[0064] Step 3: Use LTSpice to simulate the preamplifier circuit and waveform acquisition

[0065] In the particle detector system, the induced current signal needs to be amplified and processed by the preamplifier for subsequent waveform acquisition and analysis. Since the response of the preamplifier circuit may cause certain distortion to the collected signal, it is necessary to use LTSpice simulation software to model and optimize the circuit to ensure the accuracy of waveform acquisition. The specific steps include:

[0066] 1) Use LTSpice to build a preamplifier circuit model, which is usually designed based on resistive input impedance and high gain characteristics.

[0067] 2) Through simulation analysis, the impact of the circuit on the detector output signal is studied, and the influence of different circuit parameters (such as gain, frequency response, etc.) on the collected waveform is studied.

[0068] 3) Simulate and optimize the circuit to ensure that the final waveform can accurately reflect the output current of the detector and reduce the distortion introduced by the circuit.

[0069] 4) Through the LTSpice simulation results, the parameters of the front circuit can be adjusted to adapt to different experimental conditions and ensure the stability and accuracy of the system, such as Figure 5 .

[0070] This technical solution combines Geant4, WeightField2 and LTSpice to simulate the entire process from ion irradiation, carrier generation and transmission to waveform acquisition of the front-end circuit. Each simulation link provides the necessary data support for the next link, ensuring that the entire system can accurately reflect the response of charged particles in the silicon detector. Through this process, we can obtain high-quality particle detection signals and provide a reliable foundation for subsequent data analysis and processing.

[0071] Example 2

[0072] Embodiment 2 of the present invention proposes a full-process physical simulation platform for a charged particle waveform acquisition system, which is implemented based on the method of embodiment 1. The platform includes:

[0073] Ionization process simulation module, used to perform particle simulation and energy deposition calculation using high-energy physics simulation software Geant4, and output energy deposition data including different depth positions;

[0074] The carrier generation and transport simulation module is used to simulate the carrier generation and transport based on the energy deposition data using the silicon microstrip detector simulation software WeightField2, and output the detector induced current diagram;

[0075] The charged particle waveform output module is used to simulate the preamplifier circuit using LTSpice software according to the detector induced current diagram and output the complete output waveform of the charged particle.

[0076] Innovation:

[0077] 1) Construction of the full-process physical simulation platform

[0078] The present invention proposes a complete physical simulation process from detector to electronics, and systematically simulates the response process of charged particles in the detector, including the interaction between particles and detectors, signal processing of electronic equipment, waveform generation and acquisition, etc. This simulation platform can accurately simulate the waveform response of particles under various conditions without the support of actual experimental hardware, filling the limitations of traditional experimental methods in waveform data acquisition.

[0079] 2) Reduce experimental costs and improve efficiency

[0080] Compared with traditional experimental methods, the present invention replaces the expensive and time-consuming experimental process with physical simulation. The acquisition of experimental data no longer relies on high-precision physical equipment (such as tandem accelerators, vacuum chambers, detectors, etc.), reducing the high equipment investment and complex experimental operation process. At the same time, the simulation platform can efficiently generate large-scale waveform data sets, greatly improving the efficiency of data acquisition.

[0081] 3) Diverse waveform data generation and extensive sample coverage

[0082] The simulation platform of the present invention can generate waveform data under different particle types, different energy levels, and different experimental conditions, avoiding the problems of insufficient sample size and narrow coverage in existing research. Through the simulation platform, various particle waveforms from light particles to heavy ions can be simulated, and different energy ranges, particle types and their corresponding waveform characteristics can be covered, especially for some particles that are difficult to obtain in experiments (such as isotopes or high-energy particles), the simulation platform can effectively supplement data gaps. The simulation platform has a high degree of scalability and flexibility, and can flexibly adjust parameters such as particle type, energy range, and detector characteristics according to different research needs and experimental conditions to generate waveform data under specific conditions. In addition, the platform can simulate a variety of experimental settings such as different detector layouts, electronics configurations, and signal acquisition methods to meet the needs of various application scenarios.

[0083] 4) Reduce the impact of experimental conditions

[0084] In traditional experiments, waveform data is often affected by various unstable factors such as experimental environment noise and equipment interference, which restricts the accuracy and reliability of the data. The present invention can control experimental parameters, environmental conditions, noise interference and other factors by simulating the entire process of interaction between particles and detectors, thereby avoiding the interference of environmental conditions on data results in the experiment.

[0085] 5) Support optimization and training of particle identification algorithms

[0086] The waveform data set generated by the simulation platform of the present invention can effectively support the optimization of particle identification algorithms based on neural networks and other methods. Compared with traditional methods that only rely on simple features such as waveform amplitude and rise time, the simulation platform can generate more complex and rich waveform data, supporting neural networks to extract more comprehensive waveform features. This data-driven approach provides more dimensional training data for particle identification algorithms, which helps to improve identification accuracy.

[0087] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention is described in detail with reference to the embodiments, it should be understood by those skilled in the art that any modification or equivalent replacement of the technical solutions of the present invention does not depart from the spirit and scope of the technical solutions of the present invention and should be included in the scope of the claims of the present invention.

Claims

1. A full-process physical simulation method for a charged particle waveform acquisition system, for providing a waveform data set of charged particles, comprising: Step 1) using high energy physics simulation software Geant4 to perform particle simulation and energy deposition calculation, and outputting energy deposition data including different depth positions; Step 2) According to the energy deposition data, the silicon microstrip detector simulation software WeightField2 is used to simulate the carrier generation and transmission, and the detector induced current diagram is output; Step 3) According to the detector induced current diagram, the preamplifier circuit is simulated using LTSpice software to output the complete output waveform of the charged particles.

2. The full-process physical simulation method for a charged particle waveform acquisition system according to claim 1, characterized in that: The full-process physical simulation includes: ionization process, plasma erosion effect, carrier transport effect, detector induced charge and pre-amplifier voltage waveform.

3. The full-process physical simulation method for a charged particle waveform acquisition system according to claim 1, characterized in that: The step 1) comprises: Step 1-1) Use high energy physics simulation software Geant4 to set the geometric parameters of the detector and related properties of the particle source; Step 1-2) Select a physical model to describe the interaction between particles and detectors; Step 1-3) performing irradiation simulation of a particle source and counting the energy deposition caused by different particles in the silicon detector; Step 1-4) obtains energy deposition data including different depth positions in micrometers and outputs them in CSV format.

4. The full-process physical simulation method for a charged particle waveform acquisition system according to claim 3, characterized in that: The geometric parameters of the detector in step 1-1) include: a nanometer-scale aluminum metallization layer and a micrometer-scale silicon layer; the relevant properties of the particle source include: the type and energy of the particles to be simulated.

5. The full-process physical simulation method for a charged particle waveform acquisition system according to claim 1, characterized in that: The step 2) comprises: Step 2-1) using the silicon microstrip detector simulation software WeightField2 to read the energy deposition data output by the high energy physics simulation software Geant4, and calculating the number of electron-hole pairs generated at each position of the detector; Step 2-2) combining the carrier transport effect and the plasma erosion effect to simulate the movement of electron-hole pairs in the silicon detector; Step 2-3) Calculate the magnitude and change of the induced current on the two electrodes of the detector and output the detector induced current diagram.

6. The full-process physical simulation method for a charged particle waveform acquisition system according to claim 1, characterized in that: The step 3) comprises: According to the detector induced current diagram, the preamplifier circuit model was established using LTSpice software based on resistive input impedance and high gain characteristics; By adjusting the circuit parameters, simulating and optimizing the preamplifier circuit model, reducing the distortion introduced by the circuit, the optimized preamplifier circuit is obtained, and the complete output waveform of the charged particle is output.

7. The full-process physical simulation method for a charged particle waveform acquisition system according to claim 6, characterized in that: The circuit parameters include gain and frequency response.

8. A full-process physical simulation platform for charged particle waveform acquisition system, characterized in that: The platform includes: Ionization process simulation module, used to perform particle simulation and energy deposition calculation using high-energy physics simulation software Geant4, and output energy deposition data including different depth positions; The carrier generation and transport simulation module is used to perform carrier generation and transport simulation based on the energy deposition data using the silicon microstrip detector simulation software WeightField2 and output the detector induced current diagram; and The charged particle waveform output module is used to simulate the preamplifier circuit using LTSpice software according to the detector induced current diagram and output the complete output waveform of the charged particle.

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