A compact radiation detector system

Abstract

The application discloses a compact radiation detector system, which is characterized by comprising a semi-closed fixing device, a SiPM, a shielding box and an upper computer; the fixing device is internally provided with a first-stage energy detection unit and a second-stage energy detection unit, and the shielding box is internally provided with a control unit and an ASIC chip; the first-stage energy detection unit is used for generating energy deposition of charged particles and sending the energy deposition to the control unit; the second-stage energy detection unit is used for collecting the residual energy of the charged particles and the energy of uncharged particles; the SiPM converts fluorescent signals output by the second-stage energy detection unit into electric signals and sends the electric signals to the control unit; the ASIC chip controls a trigger threshold of the first-stage energy detection unit, collects signals generated in the first-stage energy detection unit after the first-stage energy detection unit is irradiated by particles and sends the signals to the control unit; the upper computer monitors and controls signals output by the control unit, and identifies an incident path, a track, a direction and a particle type of the particles.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of space high-energy irradiation detection, and particularly relates to a compact radiation detector system based on a SiC-based micro-strip + LYSO scintillation crystal. BACKGROUND

[0002] Monitoring the orbital space environment is one of the important work to ensure the safety of space engineering. Long-term in-orbit detection of space environment elements can provide important basis for studying the mechanism of space environment affecting spacecraft and astronauts, and can also provide necessary space environment parameters for scientific test loads on space stations. The space radiation effects that have greater impact on satellites, such as total dose effect, single particle effect, satellite surface charging / discharging effect, and high-energy electron internal charging effect, are mostly caused by high-flux charged particles. For strong irradiation and high-temperature environment in future space missions, improving the radiation resistance and high-temperature adaptability of the detector can reduce the consumption of resources such as weight and power consumption required for radiation resistance and refrigeration; in addition, improving the radiation length, mechanical resistance and radiation hardness of the scintillator detector can reduce the design difficulty and resource consumption of space radiation detection, and effectively prolong the service life of the detector.

[0003] In view of the detection requirements of space irradiation environment, it is urgent to develop a space radiation detector that is resistant to radiation, high temperature and position sensitive. SUMMARY

[0004] The application aims to provide a compact radiation detector system based on a SiC-based micro-strip detector + LYSO scintillation crystal. The incident end of the multi-layer SiC micro-strip detector + LYSO crystal is used as a scheme for capturing particles in space, and the energy response obtained by the placement structure of the multi-layer SiC detector can be used to determine the path and angle of particle motion. The energy deposition of the particles collected by the first-stage energy detection unit composed of SiC detectors and the second-stage energy detection unit composed of LYSO scintillation crystals is dE and E respectively, and the host computer can determine the type of particles according to the formula dE x E = Mz 2 x, where x is the thickness of the detector; z is the charge of the charged particle, and M is the mass of the particle; and the structure of the SiC micro-strip can be used to determine the incident path and trajectory of the particles. The readout electronics is equipped with an ASIC + FPGA readout scheme, and the entire device provides a small, comprehensive and stable detection system for particle radiation detection in harsh environmental conditions.

[0005] To achieve the above object, the technical scheme of the application is as follows:

[0006] A compact radiation detector system characterized in comprising a semi-closed fixing device, a SiPM, a shielding box and a host computer; the fixing device is internally provided with a first-stage energy detection unit and a second-stage energy detection unit, and the shielding box is internally provided with a control unit and an ASIC chip;

[0007] The first-stage energy detection unit is used for energy deposition of the charged particles and sending the energy deposition to the control unit; the deposited energy is denoted as dE;

[0008] The second-stage energy detection unit is used for collecting the residual energy of the charged particles and the energy of the uncharged particles output by the first-stage energy detection unit; the sum of the residual energy of the charged particles and the energy of the uncharged particles is denoted as E;

[0009] The SiPM is connected with the second-stage energy detection unit and is used for converting the fluorescent signal output by the second-stage energy detection unit into an electric signal and sending the electric signal to the control unit;

[0010] The ASIC chip is used for controlling the trigger threshold of the first-stage energy detection unit, collecting the signal generated inside the first-stage energy detection unit after being irradiated by particles and sending the signal to the control unit;

[0011] The control unit is used for data interaction with the host computer;

[0012] The host computer is used for monitoring and controlling the signal output by the control unit, identifying the incident path, trajectory and direction of the charged particles according to the deposited energy dE output by the first-stage energy detection unit, and judging the particle species according to dE and E.

[0013] Further, the first-stage energy detection unit is a telescope structure and comprises at least four layers of SiC-based semiconductor detectors, which are used for generating different energy deposition of the incident particles; wherein the microstrips in the adjacent two layers of SiC-based semiconductor detectors are perpendicular.

[0014] Further, the second-stage energy detection unit is a LYSO scintillation crystal; the spacing between the adjacent two layers of SiC-based microstrip detectors is 2 cm, the distance between the uppermost layer of SiC-based microstrip detector and the polyimide window at the particle incident end is 15 mm, and the distance between the lowermost layer of SiC-based microstrip detector and the LYSO scintillation crystal is 4 cm.

[0015] Further, the detection area of the SiC-based microstrip detector is 4 cm x 4 cm, the thickness range is 40-200 μm, the strip width of the microstrip is 100-500 μm, and the strip spacing of the microstrip is 150-550 μm.

[0016] Further, the LYSO scintillation crystal is an inorganic scintillator, and the volume is 3cm*3cm*3cm.

[0017] Further, the method for identifying the incident path, track and direction of the charged particle according to the deposited energy dE output by the first-stage energy detection unit is as follows: when the particle is incident, the information collected by a microstrip in the first layer of SiC-based microstrip detectors is x1, the information collected by a microstrip in the second layer of SiC-based microstrip detectors is y1, and the spatial coordinates of the particle passing through the first two layers of SiC-based microstrip detectors are set as (x1, y1); the information collected by a microstrip in the third layer of SiC-based microstrip detectors is x2, the information collected by a microstrip in the fourth layer of SiC-based microstrip detectors is y2, and the spatial coordinates of the particle passing through the last two layers of SiC-based microstrip detectors are set as (x2, y2); and the incident path, track and direction of the current particle are determined through the two sets of coordinates (x1, y1) and (x2, y2).

[0018] The system comprises a fixing device with a semi-closed structure, in which a plurality of layers of SiC-based microstrip detectors are sequentially fixed as a first-stage energy detection unit for obtaining the direction of the charged particle in space and collecting the partial energy deposition dE, and the X-rays without charge have no energy deposition therein; the LYSO scintillation crystal is used as a second-stage energy detection unit for collecting the total energy of the particles which are not completely deposited at the first stage and the particles without charge, and the excited particles emit the scintillation photons with a wavelength close to visible light, i.e. the fluorescence signal, after the ionization and excitation of the atoms (or ions, molecules) in the LYSO scintillation crystal caused by the incident particles; the SiPM is pasted behind the LYSO scintillation crystal for leading out the fluorescence signal generated by the scintillation crystal; the incident end of the particle is covered with a window composed of a polyimide double-sided aluminum film for blocking the interference of visible light on the detector; and the metal shielding box has a power supply assembly, a SiPM readout PCB board, an ASIC chip for reading the signals of the SiC strip detector, an ASIC peripheral circuit board, an FPGA functional module for collecting and processing the signals of the detection unit and performing data exchange, etc., and the data exchange with the upper computer is performed through network transmission.

[0019] The SiC-based semiconductor detector is used as a first-stage energy detection unit, which comprises at least four layers of thin SiC-based semiconductor detectors, and adjacent two layers of SiC-based semiconductor detectors are vertically arranged. Through the plurality of layers of SiC-based semiconductor detectors, different types of particles in space can deposit different energies when passing through the plurality of layers of detectors, and the deposited energy dE of the particles passing through different layers of SiC microstrips is obtained. Through the comprehensive analysis of the deposited energy of the second-stage detector, the incident particle type can be accurately identified, and through the installation mode of the adjacent vertically arranged microstrips, the two-dimensional position information of the charged particle can be obtained through the channel number of the microstrip hit by the particle, so as to determine the particle motion track and the incident angle.

[0020] SiPM photosensitive side uses silicon glue to stick tightly behind the LYSO scintillation crystal, and the other end is inserted into a specific PCB circuit board to lead out the signal.

[0021] LYSO scintillation crystal as the second level energy detection unit, for the cube structure matching the SiC microstrip geometry, installed in the fixed device bottom, used to collect the remaining deposited energy E after the particle through the first level energy detection unit; except the top, the four around are wrapped with reflective material to improve the collection efficiency.

[0022] Power supply components for SiC-based semiconductor detectors and SiPM to provide working bias voltage.

[0023] SiPM readout PCB board for collecting SiPM on LYSO scintillation crystal fluorescence signal conversion of electrical signal amplification, shaping, and through the cable.

[0024] ASIC chip is set on the ASIC chip peripheral circuit board by patch welding, used to control the trigger threshold of the first level energy detection unit SiC-based microstrip detector, collect the number of electron-hole pairs generated inside the multi-channel SiC microstrip detector after particle irradiation and calculate the number of charges for sensitive amplification, signal shaping, and data transmission to the control unit.

[0025] The FPGA function module in the control unit is used to realize the conversion of the input power, communication with the host computer, system parameter configuration and data management, ASIC calibration, clock and trigger distribution, and busy signal collection, etc. The collected data includes the position information of the particle hitting the SiC-based microstrip detector, the energy deposited by the particle in the multi-layer SiC microstrip detector, and the energy deposited by the particle in the LYSO scintillation crystal. Through software calculation, we collect specific information such as the path, angle, and type of the incident particle.

[0026] The host computer is used to configure the ASIC chip and monitor and control the signal output by the FPGA module.

[0027] Implementation of particle species discrimination:

[0028] Various particles in space such as electrons, protons, alpha particles, and gamma rays enter the system from the incident end, and their reactions with the detector are different;

[0029] Uncharged particles such as low-energy X / γ rays have low detection efficiency in the first level detector and basically no energy deposition, while the second level detector has high atomic number and density value, and X / γ rays have high detection efficiency, which can achieve full energy deposition.

[0030] As a light particle with one unit of electric charge, the electron / positron will deposit a small amount of energy in the first stage detector and deposit the full energy in the second stage detector. The deposited energy of the electron in the first stage detector will be significantly less than that of the proton and heavy ion with the same incident energy.

[0031] The proton and alpha particle are heavy ions with one and two units of positive charge, respectively. The effect of the proton and alpha particle on the detector is mainly ionization. The deposited energy is related to the charge and atomic number.

[0032] The track of the charged particle can be detected by the four-layer SiC microstrip design. The charge signal and deposited energy of different particles in different SiC are proportional. The signal obtained after linear amplification by the ASIC is still proportional to the deposited energy. Therefore, the energy deposition number dE in different layers can be obtained by the electrical signal. i (i = 1, 2, 3, 4), and in the LYSO crystal, the fluorescence intensity generated by the crystal is proportional to the deposited energy. The fluorescence signal can be converted into an electrical signal proportional to the energy by the SiPM, and then the total energy E of the particle can be obtained. Through the Bet formula: dE n × E n = Mz 2 Δx can be obtained, dE n × E n is related to the mass M and charge z of the charged particle. The charge and mass of the proton, electron, and different types of heavy particles are different. Through this discriminant, the particle type is screened. The uncharged particles, such as gamma rays, do not deposit energy in the first stage SiC microstrip detector. The main energy deposition occurs in the LYSO scintillation crystal of the second stage energy detection unit. Therefore, through this combination of multi-layer SiC microstrip detector + LYSO scintillation crystal, the incident particle type and energy can be detected.

[0033] Extraction of particle incident angle and position:

[0034] The multi-layer SiC microstrip detector of the first stage energy detection unit is designed with the adjacent two layers of microstrips perpendicular to each other. When the particle hits the microstrip, the information collected by the first two layers of microstrips can be used as a coordinate (X1, Y1). When the particle hits the second two layers of microstrips after passing through the first two layers of microstrips, the information collected at this time can be used as a coordinate (X2, Y2). Through the two coordinate points, the propagation path of the particle in the detection system can be obtained, and the extraction of the particle incident position and angle can be realized.

[0035] The back-end electronics comprises: an ASIC chip peripheral circuit for ensuring the normal working circuit of the ASIC chip; a SiPM readout collection PCB board for collecting SiPM signals and performing shaping, amplification, filtering and other functions, a power conversion circuit for powering the ASIC chip and other electronic devices, a high-voltage power supply circuit for providing bias high voltage for the SiC-based micro-strip detector and the SiPM, and a communication circuit comprising an FPGA module for data collection and processing, control and management of the entire readout electronics, and external communication functions.

[0036] The SiC micro-strip detector signal is transmitted to the connector through the PCB board wiring and connected to the ASIC chip in the back-end electronics for charge-sensitive amplification and shaping of the SiC micro-strip detector signal; and then transmitted to the FPGA module through the ADC for digital-to-analog conversion. The signal of the LYSO scintillation crystal is led out by the SiPM pasted behind it, the SiPM converts the fluorescence signal of the LYSO scintillation crystal into an electrical signal, and transmits it to the transimpedance amplifier of the back-end electronics for signal amplification processing, and then transmits it into the FPGA after filtering and shaping. Through the FPGA module, the power conversion control of the back-end electronics, the data acquisition and digitization of the ASIC chip, the ASIC calibration, the selection of the threshold value, the distribution of the clock and the trigger, and the collection of the running busy signal, the FPGA forms data containing the incident particle event number, the first-level four-layer SiC strip deposited energy information, and the second-level LYSO crystal deposited energy information, and compares the above data with the comparison table containing particle type information and energy information given by the simulation and calibration experiment results, to give the particle type and the energy grouping information (the method is similar to CN201410133942 Tables 1 and 2, but the detector digitization value grouping and selection standard will be different), and the position information of each layer of SiC strip hit by the particle is also output. The FPGA frames the above data and transmits and exchanges the data with the PC end.

[0037] The distance between the multi-layer SiC-based micro-strip detectors is 2 cm. In the simulation using the simulation software Geant-4, the distance between the adjacent SiC-based micro-strip detector layers should be within 1-2 cm to make the energy spectrum response of all the detectors good and the noise low, and the micro-strips of the two adjacent layers are perpendicular to each other. Through this arrangement, we can obtain multiple spatial coordinate points to facilitate the determination of the trajectory of the incident particle. The distance between the uppermost SiC-based micro-strip detector and the polyimide window at the particle incident end is 15 mm, so that the particles in space can be captured by the SiC detector to the maximum extent, avoiding the reflection of the particles hitting the side wall of the device. The distance between the bottommost SiC-based micro-strip detector and the LYSO scintillation crystal is 4 cm.

[0038] The SiC-based micro-strip detector has an area of 4cm*4cm, a thickness of 40-200μm, a strip width of 100-500μm, and a strip spacing of 150-550μm.

[0039] The SiC-based micro-strip detector can convert incident particle deposition energy into electron-hole pairs, and the electron-hole pairs are proportional to the deposition energy, and the deposition energy of the SiC-based micro-strip detector is denoted as dE.

[0040] The LYSO crystal is an inorganic scintillator, and has a volume of 3cm*3cm*3cm. In use, the LYSO crystal is coated with a reflective material to improve light collection efficiency. The LYSO scintillation crystal can convert incident particle deposition energy into a fluorescent signal, and the light signal flux is proportional to the incident particle energy.

[0041] The SiPM photosensitive surface is bonded to the surface of the LYSO crystal by silicone, and the other surface of the SiPM is fixed to a specially designed PCB board, and the signal is led out through connectors and cables.

[0042] The SiPM readout acquisition PCB board includes a power supply circuit and an amplification circuit. The power supply circuit is used to provide a stable voltage for electronic components, and the amplification circuit is used to shape and amplify the signal of the SiPM.

[0043] The ASIC chip can realize charge-sensitive amplification of the signal formed by the electron-hole pairs generated by the SiC semiconductor detector, and the amplified signal is proportional to the deposition energy, and the energy deposition value of each SiC unit can be extracted.

[0044] The ASIC chip integrates a charge-sensitive preamplifier, an ADC, a shaping circuit and the like. The input end of the charge-sensitive preamplifier in the ASIC chip is connected to the signal output end of the SiC-based micro-strip detector through a pin led out by PCB wiring, and is used to shape and amplify the signal output by the SiC-based micro-strip detector, and transmit the amplified signal to the ADC. The ADC is used to convert the analog signal output by the charge preamplifier into a digital signal and send it to the FPGA module. The PC end of the upper computer is used to obtain and present the energy spectrum information generated by the SiC micro-strip detector under working conditions according to the digital signal processed by the FPGA module.

[0045] The shaping circuit in the ASIC chip includes a fast shaping amplifier and a slow shaping amplifier. The fast shaping amplifier can input a discriminator to form a trigger signal pulse generator, and the slow shaping amplifier can input a sample-and-hold circuit to extract signal amplitude information.

[0046] The ADC within the ASIC chip is used to digitize the sampler output processed by the slow shaping amplifier, and the type of ADC has 10-bit resolution, and each channel has an ADC for converting the collected analog signal to a digital signal.

[0047] The number of channels of the ASIC chip and the input ends of all charge preamplifiers should be the same as the number of effective strips of the SiC microstrip detector signal output.

[0048] The software design of the FPGA functional module includes configuration functions of ASIC functional parameters, logic selection functions, address information and case classification packaging storage functions of hit strips, and functions such as self-detection, mode switching, acquisition control, gain correction and configuration data. Through the control of the upper computer, the effectiveness, accuracy and flexibility of the detection data extracted by the electronic system are ensured.

[0049] The host PC controls the FPGA to generate readout control signals and control the A / D conversion circuit. The A / D converter continuously samples under the control of the sampling clock to convert the analog signal into a continuous data stream, ensuring that no data is lost under high flow intensity. Each strip detector is digitized in the same way, and the received digital signal is processed to obtain signal amplitude information and displayed.

[0050] The peripheral circuit of the ASIC chip includes power supply circuit, filter circuit, SiC microstrip detector readout circuit, digital isolation circuit, etc. The power supply circuit is used to provide working voltage for the ASIC chip, the filter circuit is used to filter the noise at the power supply end, the SiC microstrip readout circuit is used to lead out the signal of the SiC microstrip detector, and the digital isolation circuit is used to collect and input the signal processed by the ASIC chip into the FPGA module end. The purpose is to further separate the digital signal from the analog signal, ensure the integrity and stability of the data, and prevent data loss.

[0051] A polyimide double-sided aluminum plated window is arranged at the particle incident end, the thickness of the polyimide is about 15 μm, the thickness of the aluminum plated layer on each side is 1 μm, and the periphery is closed with light shielding material to shield light interference. SiC microstrip and the like are sensitive to light and need to be used in the dark to achieve the best detection efficiency.

[0052] The compact radiation detector system based on the SiC micro-strip + LYSO scintillation crystal provided by the application comprises a SiC micro-strip detector, a LYSO crystal, a SiPM, a fixing device, a power supply assembly, a SiPM readout PCB board, an ASIC chip, an ASIC peripheral circuit board, an FPGA functional module, a metal shielding box and an upper computer. The SiPM is pasted behind the LYSO crystal by using silica gel; at least four layers of SiC micro-strip detectors are installed on the upper side of the LYSO crystal in a perpendicular manner, and are all aligned with the LYSO crystal, and together form a telescope structure and serve as an incident end of the radiation particle detection, the SiC micro-strip detector serves as a first-stage energy detection unit, and the LYSO scintillation crystal serves as a second-stage energy detection unit. The ASIC chip and the peripheral circuit board in the rear-end electronics are used for collecting the number of electron-hole pairs generated by the multiple SiC detector micro-strips of the first-stage energy detection unit after being irradiated and calculating the number of charges, and amplifying and collecting and holding signals; the peripheral circuit board of the ASIC chip is used for providing working voltage, filtering, protecting the ASIC chip and further isolating digital / analog signals for the ASIC chip and the SiC micro-strip detector, and simultaneously connecting the FPGA functional module through connectors and PCB wiring, so as to realize multi-channel readout of the detector signals. The FPGA module is connected with the ASIC peripheral circuit board and the SiPM readout PCB board at one end, and the dE i and E are used for comparing the particle types, collecting the position information of the energy deposition generated by the SiC micro-strips of different positions in different layers when the particles pass through the SiC detector, determining the incident angle of the particles by calculation, and obtaining the path of the particles when passing through the micro-strips through the energy response of the micro-strips. Meanwhile, the FPGA module is adapted to the input signal range of the high-speed ADC at one end; the A / D conversion circuit is controlled to continuously sample under the control of a sampling clock, and the analog signal is converted into a continuous data stream, so that each channel of the strip detector is digitized in the same way, the data stream input and output design is completed, and the data transmission and instruction response functions are realized.

[0053] The innovation of the present application is to design a telescope structure scheme using a multilayer SiC microstrip detector + LYSO crystal. First, the uppermost in the fixing device, the SiC detector end adopts a multilayer structure as a first energy detection unit, and through the adjacent vertical microstrip structure, the response of the different microstrip positions hit when the particles are incident can determine the exact position, angle, time and path of the particle incidence. The LYSO scintillation crystal is arranged 4 cm below the SiC detector as a second energy detection unit. When the particles pass through the SiC detector end, they will continue to be incident into the LYSO crystal, and the fluorescence signal generated thereby is converted into an electrical signal by the SiPM. The energy spectrum response of the two-stage energy detection unit realizes the judgment of the type of particles. Secondly, the readout system adopts an ASIC + FPGA readout system, so that the volume, power consumption, convenience, stability and the like of the device are greatly improved, and multiple signals of the SiC microstrip detector and the LYSO crystal can be processed at the same time. Through the present application, the position, angle, time, path and type of the incident particles can be determined, the convenience of the readout device is optimized, the particle detection efficiency is improved, the influence of the change of the experimental environment on the stability of the experimental system is reduced, and a more stable, efficient and convenient readout system is provided for signal multi-channel readout in more complex experimental environments and a large number of particle types. BRIEF DESCRIPTION OF DRAWINGS

[0054] Figure 1 It is a compact radiation detector system structure diagram based on SiC-based microstrip + LYSO scintillation crystal.

[0055] Figure 2 It is a structural block diagram of the device.

[0056] Figure 3 It is a swing diagram, a top view of the SiC detector and a size diagram of the LYSO crystal.

[0057] (a) is a top view of the adjacent two layers of SiC detector microstrips placed vertically to each other,

[0058] (b) is a schematic view of the adjacent two layers of SiC detector microstrips,

[0059] (c) is a size diagram of the LYSO crystal.

[0060] Explanation of reference numerals: 1-SiC-based microstrip detector; 2-LYSO scintillation crystal; 3-SiPM; 4-power module; 5-SiPM readout PCB board; 6-ASIC chip; 7-ASIC peripheral circuit board; 8-FPGA module; 9-shielding box; 10-upper computer PC end; 11-fixing device. DETAILED DESCRIPTION

[0061] The application will be further described in detail below with reference to the accompanying drawings.

[0062] Embodiment 1

[0063] As Figure 1 shown, a compact radiation detector system based on SiC microstrip + LYSO scintillation crystal, comprising a SiC microstrip detector (1), a LYSO scintillation crystal (2), a SiPM (3), a power supply module (4), a SiPM readout PCB board (5), an ASIC chip (6), an ASIC peripheral circuit board (7), an FPGA functional module (8), a metal shielding box (9), and an upper computer (10). The specific connection mode of the embodiment is as follows:

[0064] A polyimide double-sided aluminum plated window is arranged on the particle incident end side, and the thickness of the polyimide is about 15 μm, and the thickness of the aluminum plated layer on each side is 1 μm.

[0065] The SiC microstrip detector (1) is fixed on the light-tight designed fixing device (11), the spacing between the SiC microstrip detectors is 2 cm, and the microstrips of the adjacent two layers are perpendicular to each other, the distance between the uppermost SiC microstrip detector and the polyimide window is 15 mm, and the distance between the bottommost SiC microstrip detector and the LYSO scintillation crystal is 4 cm. One end of the connector is led out by a cable and used for connecting the power supply module (4) and the ASIC peripheral circuit board (7) to provide the bias working voltage of the SiC microstrip and the signal readout.

[0066] The SiPM (3) is pasted behind the LYSO crystal (2) using a photosensitive adhesive, and one end is connected to the SiPM readout PCB board (5) through a connector and a cable. The power supply module (4) is connected to the SiPM readout PCB board (5) through a cable to provide the bias voltage of the SiPM.

[0067] The LYSO scintillation crystal (2) is located 4 cm below the SiC microstrip detector (1), and the outer side of the LYSO scintillation crystal (2) needs to be wrapped with a light reflecting material and fixed to improve the collection efficiency.

[0068] The ASIC chip (6) is located above the ASIC peripheral circuit board (7) by means of surface mount welding, and the input end is led out to the connector end through PCB wiring and connected to the connector of the SiC microstrip detector (1) through a cable.

[0069] One end of the ASIC peripheral circuit board (7) is coupled with the SiC microstrip detector (1) through an electronic connector and a cable, and the other end is coupled with the FPGA module. The ASIC peripheral circuit board (7) has the following functions: power supply circuit, filter circuit, circuit function for ASIC calibration and mode conversion, digital analog signal isolation circuit, and signal transmission into the rear-end FPGA module.

[0070] SiPM readout circuit board (5) one end is connected to SiPM through cable, one end is connected to FPGA function module (8). Its PCB board has power filter circuit, cross group amplifier, which is used to filter the SiPM bias voltage provided by power module (4), and convert the current signal output by SiPM into voltage signal output, and amplify the tiny signal.

[0071] FPGA module (8) one end is connected to ASIC peripheral circuit board (7), the functions in FPGA module include: logic selection function, address information and case classification packaging storage function of hit strip, and self detection, mode switching, acquisition control, gain correction and configuration data function. Through the control of host computer, the effectiveness, accuracy and flexibility of the detection data extracted by electronic system are ensured.

[0072] ASIC chip (6), ASIC peripheral circuit board (7), SiPM readout PCB board (5), FPGA function module (8) are installed in the metal shielding box to reduce the electromagnetic interference of the environment and prevent excessive noise from collecting effective signals.

[0073] SiC microstrip detector (1) will ionize to produce electron hole pairs after particle irradiation, which will be quickly separated to the electrode under the action of bias voltage and collected, generating signal response and being collected and processed by ASIC chip (6). In the four layer SiC microstrip detector structure, the uncharged particles are difficult to deposit energy in the first layer, which may deposit energy in the next few layers of SiC microstrip detector or enter the LYSO scintillation crystal, so the signal threshold of the last few layers is set different from that of the first layer to determine whether the particle is charged. The electrons, alpha particles and protons in the charged particles may deposit energy in the device, but the deposition energy of the electrons decreases layer by layer, so they can also be distinguished.

[0074] For the discrimination of particle incident path and angle, we set the information collected by the first layer of microstrip in the first two layers of microstrip perpendicular to each other as x1, and the information collected by the second layer of microstrip as y1. Then the spatial coordinates of the particles passing through the first two layers can be set as (x1, y1), and the last two layers can be written as (x2, y2) in the same way. Through the two sets of coordinates, we can determine that the path of the particle satisfies the law of linear function, so we can get the determined path of the particle incident, which is recorded as the path of the particle incident this time, and the angle can be calculated. The output voltage pulse value V0 of SiC microstrip detector can be represented as: Where A is the amplification gain, Q i is the input charge of charge sensitive preamplifier in ASIC chip; C i is the sum of amplifier input capacitance and distributed capacitance; C fC d The equivalent capacitance value of the SiC micro-strip detector.

[0075] The charge-sensitive preamplifier integrated in the ASIC chip (6) is divided into fast and slow shaping amplifiers. The fast shaping amplifier forms a trigger signal pulse generator for the input discriminator and transmits the amplified signal to the slow shaping amplifier. The holding circuit of the slow shaping amplifier extracts the signal amplitude information and collects the signal data. The ADC then converts the analog signal into a digital signal.

[0076] The ASIC chip (6) has 32 10-bit ADCs;

[0077] The back end of each charge-sensitive preamplifier of the ASIC chip (6) is connected to a 2μs shaper and a 0.6μs comparator for triggering readout. The dynamic range of the input charge of this chip is up to ±90fC.

[0078] After the particle passes through the SiC detector (1), it continues to enter the LYSO scintillation crystal (2). The crystal converts the deposited energy of the incident particle into a fluorescence signal, and the size of the fluorescence signal is proportional to the energy of the incident particle. The crystal is wrapped in reflective material on one side, and the SiPM is pasted on one side. At this time, the SiPM collects the fluorescence signal of the crystal and converts it into a current signal output. The SiPM is essentially a p-n junction, which works in a reverse bias state. When a photon is incident on its surface, an electron-hole pair is generated. This process is similar to a photodiode. At this time, the current value I in is proportional to the input photon intensity. The back-end amplification circuit mainly uses a transimpedance amplifier to convert the current signal output by the SiPM into a voltage signal for output V out =I in ×R f , where R f is the feedback resistance of the transimpedance amplifier.

[0079] The host PC end configures the FPGA by compiling the Verilog language, thereby generating readout control signals and controlling the A / D conversion circuit to work. The A / D converter continuously samples under the control of the sampling clock, converting the analog signal into a continuous data stream, ensuring that no data is lost even at high flow intensity. Each strip detector is digitized in the same way.

[0080] The required bias voltage of the SiC micro-strip detector (1) is -40V.

[0081] The required bias voltage of the SiPM (3) is 36V.

[0082] The SiPM readout PCB includes a power supply circuit and a cross-group amplification circuit, the power supply circuit is used to provide a bias voltage for the SiPM, and the amplification circuit is used to shape and amplify the signal of the SiPM.

[0083] When the n channels of the ASIC chip (6) are read out, the readout time is (9+n)us. Without zero suppression, the readout time of the ASIC is 73us.

[0084] The power supply circuit of the ASIC chip (6) is arranged on the peripheral circuit board of the ASIC, and the ASIC requires two power supply voltages of-2V and+1.5V, and the total power is 19mW.

[0085] The core board of the FPGA module uses the core model ZYNQ XC7Z035.

[0086] The driver program of the FPGA is compiled, simulated and programmed using the Vivado software, and the programming language uses Veirlog language.

[0087] The position, information, energy spectrum and other data information of the readout are collected by the upper computer software written by the PYQT software on the PC end (10) of the upper computer.

[0088] The above specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present application. It should be understood that the above examples are only illustrative of the present application and do not limit the protection scope of the present application. Any design identical or similar to the present application belongs to the protection scope of the present application.

Claims

1. A compact radiation detector system, characterized in that: It includes a semi-enclosed fixture, SiPM, shielding box and host computer; the fixture is equipped with a first-level energy detection unit and a second-level energy detection unit, and the shielding box is equipped with a control unit and an ASIC chip; The first-stage energy detection unit is used to generate energy deposition for charged particles and send it to the control unit; the deposited energy is recorded as dE; wherein the first-stage energy detection unit is a telescope structure, including at least four layers of SiC-based microstrip detectors, which are used to generate different energy depositions for incident particles; the microstrips in two adjacent layers of SiC-based microstrip detectors are perpendicular; The second-stage energy detection unit is used to collect the residual energy of the charged particles and the energy of the uncharged particles output by the first-stage energy detection unit; the sum of the residual energy of the charged particles and the energy of the uncharged particles is recorded as E; wherein, the second-stage energy detection unit is a LYSO scintillation crystal, the spacing between two adjacent layers of the SiC-based microstrip detectors is 2 cm, the distance between the topmost SiC-based microstrip detector and the polyimide window at the particle incident end is 15 mm, and the distance between the bottommost SiC-based microstrip detector and the LYSO scintillation crystal is 4 cm; The SiPM is connected to the second-stage energy detection unit and is used to convert the fluorescence signal output by the second-stage energy detection unit into an electrical signal and send it to the control unit; The ASIC chip is used to control the trigger threshold of the first-stage energy detection unit, collect the signal generated internally by the first-stage energy detection unit after being irradiated by particles, and send it to the control unit; The control unit is used to exchange data with the host computer; The host computer is used to monitor and control the signal output by the control unit, and to identify the particle incident path, trajectory, and direction of the charged particles based on the deposited energy dE output by the first-stage energy detection unit, and to determine the particle type based on dE and E.

2. The compact radiation detector system according to claim 1, characterized in that The detection area of ​​the SiC-based microstrip detector is 4cm×4cm, the thickness ranges from 40 to 200 μm, the width of the microstrip is 100 to 500 μm, and the spacing between the microstrips is 150 to 550 μm.

3. The compact radiation detector system according to claim 1, wherein: The LYSO scintillation crystal is an inorganic scintillator, and its volume is 3cm*3cm*3cm.

4. The compact radiation detector system according to claim 1, wherein: The method for identifying the incident path, trajectory, and direction of the charged particle based on the deposited energy dE output by the first-level energy detection unit is as follows: when the particle is incident, the information collected by a microstrip in the first layer of SiC-based microstrip detectors is x1, and the information collected by a microstrip in the second layer of SiC-based microstrip detectors is y1, then the spatial coordinates of the particle passing through the first two layers of SiC-based microstrip detectors are set to (x1, y1); the information collected by a microstrip in the third layer of SiC-based microstrip detectors is x2, and the information collected by a microstrip in the fourth layer of SiC-based microstrip detectors is y2, then the spatial coordinates of the particle passing through the last two layers of SiC-based microstrip detectors are set to (x2, y2); the incident path, trajectory, and direction of the charged particle of the current particle are determined by the two sets of coordinates (x1, y1) and (x2, y2).

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