Compact radiation detector system

Abstract

The invention 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, a first-stage energy detection unit and a second-stage energy detection unit are arranged in the fixing device, and a control unit and an ASIC chip are arranged in the shielding box; the first-stage energy detection unit is used for generating energy deposition for charged particles and sending the energy deposition to the control unit; the second-stage energy detection unit is used for collecting residual energy of charged particles and energy of uncharged particles; the SiPM converts a fluorescence signal output by the second-stage energy detection unit into an electric signal and sends the electric signal to the control unit; the ASIC chip controls a trigger threshold value 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; and the upper computer monitors and controls the signal output by the control unit, and identifies the incident path, track and direction of the particles and the types of the particles.

Description

Technical Field

[0001] The invention belongs to the technical field of space high-energy radiation detection, and in particular relates to a compact radiation detector system based on SiC-based microstrips + LYSO scintillation crystals. Background Art

[0002] Monitoring the orbital space environment is one of the important tasks to ensure the safety of aerospace engineering. Long-term on-orbit detection of space environment factors can provide an important basis for studying the mechanism of the space environment's harmful effects on spacecraft and astronauts, and can also provide necessary space environment parameters for scientific experimental payloads on the space station. Space radiation effects that have a greater impact on satellites, such as total dose effects, single particle effects, satellite surface charging / discharging effects, and internal charging effects of high-energy electrons, are mostly caused by high-flux charged particles. For strong radiation and high-temperature environments in future space missions, improving the radiation resistance and high-temperature adaptability of detectors 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 scintillator detectors are of great significance for reducing the design difficulty and resource consumption of space radiation detection and effectively extending the life of detectors.

[0003] In order to meet the detection needs of space radiation environment, there is an urgent need to develop radiation-resistant, high-temperature-resistant and position-sensitive space radiation detectors. Summary of the invention

[0004] The purpose of the present invention is to propose a compact radiation detector system based on SiC-based microstrip detector + LYSO scintillation crystal. The multi-layer SiC microstrip detector + LYSO crystal incident end is used as a solution for capturing particles in space. 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 movement. The energy deposition of 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 are dE and E respectively. The host computer uses the formula dE×E=Mz 2 x can be used to judge the type of particles, where x is the thickness of the detector; z is the charge of the charged particles, and M is the mass of the particles; and the SiC microstrip structure is used to determine the particle incident path and trajectory. The readout electronics is equipped with an ASIC+FPGA readout solution, and the entire device provides a small, comprehensive, and stable detection system for particle radiation detection in harsh environments.

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

[0006] A compact radiation detector system, characterized in that it comprises a semi-enclosed fixture, a SiPM, a shielding box and a host computer; the fixture is provided with a first-stage energy detection unit and a second-stage energy detection unit, and the shielding box is provided with a control unit and an ASIC chip;

[0007] The first-stage energy detection unit is used to generate energy deposition on the charged particles and send it to the control unit; the deposited energy is recorded as dE;

[0008] 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; wherein 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 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;

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

[0011] The control unit is used to perform data exchange with the host computer;

[0012] The host computer is used to monitor and control the signal output by the control unit, and to identify the incident path, trajectory, and direction of the charged particles according to the deposited energy dE output by the first-level energy detection unit, and to judge the type of particles according to dE and E.

[0013] Furthermore, the first-stage energy detection unit is a telescope structure, including at least four layers of SiC-based semiconductor detectors, which are used to produce different energy depositions on incident particles; wherein the microstrips in two adjacent layers of SiC-based semiconductor detectors are vertical.

[0014] Furthermore, the second-level 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.

[0015] Furthermore, the detection area of ​​the SiC-based microstrip detector is 4 cm×4 cm, 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.

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

[0017] Furthermore, the method for identifying the incident path, trajectory, and direction of the charged particle according to 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 two sets of coordinates (x1, y1) and (x2, y2).

[0018] The system includes a semi-enclosed fixing device, in which multiple layers of SiC-based micro-strip detectors are fixed in sequence as the first-level energy detection unit for obtaining the direction of charged particles in space and collecting part of the energy deposition dE, and no energy is deposited in the uncharged X-rays; LYSO scintillation crystals are used as the second-level energy detection unit to collect the total energy of particles and uncharged particles that have not been completely deposited in the first level, and the ionization excitation of atoms (or ions, molecules) in the LYSO scintillator caused by the incident particles, and the excited particles de-excite to emit scintillation photons with a wavelength close to visible light, that is, fluorescence signals; SiPM is pasted behind the LYSO scintillation crystal to lead out the fluorescence signal generated by the scintillation crystal, and the particle incident end is covered with a window composed of a double-sided aluminum-plated polyimide film to block the interference of visible light on the detector. A metal shielding box contains: a power supply component, a SiPM readout PCB board, an ASIC chip for reading out the SiC strip detector signal, an ASIC peripheral circuit board, and an FPGA functional module for collecting and processing the signals of the detection unit and exchanging data, etc., and exchanging data with a host computer through network transmission.

[0019] Among them, the SiC-based semiconductor detector serves as the first-level energy detection unit, which includes at least four layers of thin SiC-based semiconductor detectors, wherein two adjacent layers of SiC-based semiconductor detectors are placed vertically. Through the multi-layer SiC-based semiconductor detectors, different types of particles in the space can deposit different energies when passing through the multi-layer detectors, and the deposition energy dE of the particles passing through different layers of SiC microstrips is obtained. Through comprehensive analysis with the deposition energy of the second-level detector, the type of incident particles can be accurately identified, and through the installation method of adjacent vertically placed microstrips, the two-dimensional position information of the charged particles can be obtained through the channel number of the particles hitting the microstrips of different layers, which is used to determine the particle motion trajectory and the incident angle.

[0020] The photosensitive side of the SiPM is tightly adhered to the back of the LYSO scintillation crystal using silicone, and the other end is inserted into a specific PCB circuit board to lead out the signal.

[0021] The LYSO scintillation crystal serves as the second-stage energy detection unit. It is a cubic structure that matches the geometric dimensions of the SiC microstrip and is installed at the bottom of the fixture to collect the remaining deposited energy E after the particles pass through the first-stage energy detection unit. Except for the top, all four sides are wrapped with reflective materials to improve the collection efficiency.

[0022] The power supply assembly is used to provide bias voltage to the SiC-based semiconductor detector and SiPM during operation.

[0023] The SiPM readout PCB board is used to collect, amplify and shape the electrical signal converted by SiPM from the fluorescence signal of the LYSO scintillation crystal, and lead it out through a cable.

[0024] The ASIC chip is arranged above the peripheral circuit board of the ASIC chip by patch welding. It is used to control the trigger threshold of the SiC-based microstrip detector of the first-stage energy detection unit, collect the number of electron-hole pairs generated inside the multi-channel SiC microstrip detectors after particle irradiation, calculate the number of charges for sensitive amplification, maintain and shape the signal, and transmit the data to the control unit.

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

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

[0027] Implementation of particle type identification:

[0028] When various particles in space, such as electrons, protons, alpha particles, and gamma rays, enter the system from the incident end, they react differently to the detector;

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

[0030] As a particle with a relatively light mass per unit charge, electrons / positrons generally deposit a small amount of energy in the first-stage detector and achieve complete energy deposition in the second-stage detector. The deposited energy of electrons in the first-stage detector is significantly smaller than the deposited energy of protons and heavy ions with the same incident energy.

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

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

[0033] Extraction of particle incident angle and position:

[0034] The multi-layer SiC microstrip detector of the first-level energy detection unit is designed so that two adjacent layers of microstrips are perpendicular to each other. When a particle is incident and hits the microstrip, the information collected from the positions of the first two layers of microstrips can be used as a coordinate (X1, Y1). When the particle passes through the first two layers of microstrips and hits the positions of the last two layers of microstrips, the information collected at this time is used as a coordinate (X2, Y2). Through the two coordinate points, we can obtain the propagation path of the particle in the detection system, thereby realizing the extraction of the particle's incident position and angle.

[0035] The back-end electronics include: ASIC chip peripheral circuits used to ensure the normal working circuits of the ASIC chip; SiPM readout acquisition PCB board used to collect SiPM signals and perform shaping, amplification, filtering and other functions; power conversion circuits used to power ASIC chips and other electronic devices; high-voltage power supply circuits used to provide bias high voltage for SiC-based microstrip detectors and SiPM; the communication circuit includes an FPGA module for overall data collection and processing, control and management of the entire readout electronics, and external communication functions.

[0036] The signal of the SiC microstrip detector is routed to the connector through the PCB board, and then connected to the ASIC chip in the back-end electronics through a cable to perform charge-sensitive amplification and shaping on the signal of the SiC microstrip detector; then the signal is converted to analog through the ADC and transmitted to the FPGA module. The signal of the LYSO scintillation crystal is derived from the SiPM attached to the back of it, and the SiPM converts the fluorescence signal of the LYSO scintillation crystal into an electrical signal; and then it is transmitted to the transimpedance amplifier of the back-end electronics for signal amplification, and then transmitted to the FPGA after filtering and shaping. Through the FPGA module, the power conversion control of the back-end electronics, the digitization of the data acquisition of the ASIC chip, the ASIC calibration, the selection of thresholds, the clock and trigger distribution, and the collection of the busy signal are carried out. The FPGA forms data containing the incident particle case number, the deposition energy information of the first-level four-layer SiC strips, and the deposition energy information in the second-level LYSO crystal. The above data are compared with the comparison table containing the particle type information and energy information given by the simulation and calibration experiment results, and the particle type and energy grouping information are given (the method is similar to Table 1 and Table 2 of CN201410133942, but the detector digitization value grouping and selection criteria will be different). At the same time, the position information of each layer of SiC strips hit by the particles is also output. The FPGA frames the above data and transmits and exchanges data with the host computer PC.

[0037] The spacing between the multi-layer SiC-based microstrip detectors is 2 cm. In the simulation using the simulation software Geant-4, the adjacent SiC-based microstrip detector layers should be within 1 to 2 cm so that all detectors have good energy spectrum response and low noise, and the microstrips of two adjacent layers are perpendicular to each other. This arrangement allows us to obtain multiple spatial coordinate points, which is convenient for determining the trajectory of the incident particles. The distance between the top SiC-based microstrip detector and the polyimide window at the particle incident end is 15 mm, so that the particles in the space are captured by the SiC detector to the greatest extent, avoiding the particles from hitting the side wall of the device and reflecting out. The distance between the bottom SiC-based microstrip detector and the LYSO scintillation crystal is 4 cm.

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

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

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

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

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

[0043] The ASIC chip can realize charge-sensitive amplification of signals formed by electron-hole pairs generated by SiC semiconductor detectors. The amplified signal is proportional to the deposited 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, etc.; wherein the charge-sensitive preamplifier input end inside the ASIC chip is connected to the SiC-based microstrip detector signal output end through a pin led out through a PCB trace, and is used to shape and amplify the signal output by the SiC-based microstrip 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 host computer PC is used to obtain and present the energy spectrum information generated by the SiC microstrip detector under working conditions according to the digital signal processed by the FPGA module.

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

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

[0047] The number of channels of the ASIC chip and the input terminals of all charge preamplifiers should be the same as the number of valid signal outputs of the SiC microstrip detector.

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

[0049] The host PC controls the FPGA to generate the readout control signal and control the A / D conversion circuit. The A / D converter continuously samples under the control of the sampling clock and converts the analog signal into a continuous data stream to ensure that data is not lost even at high current intensity. Each strip detector is digitized in the same way and the received digital signal is processed to obtain the signal amplitude information and displayed.

[0050] The ASIC chip peripheral circuit includes a power supply circuit, a filter circuit, a readout circuit of a SiC microstrip detector, a digital isolation circuit, etc., wherein the power supply circuit is used to provide an operating voltage to the ASIC chip, the filter circuit is used to filter the noise at the power supply end, etc., the SiC microstrip readout circuit is used to draw out the signal of the SiC microstrip detector. At the same time, the SiC microstrip detector needs to work in a biased high-voltage state, and the readout circuit also plays a role in protecting the ASIC chip. The digital isolation circuit is used to collect the signals processed by the ASIC chip and input them into the FPGA module end. Its purpose is to further separate the digital signal from the analog signal, ensure the comprehensiveness and stability of the data, and prevent data loss.

[0051] A polyimide double-sided aluminum-plated window is set at the particle incident end. The thickness of the polyimide is about 15μm, the thickness of the aluminum-plated layer on each surface is 1μm, and it is closed with shading materials on all sides to shield light interference. SiC microstrips are sensitive to light and need to be used away from light to achieve the best detection efficiency.

[0052] The compact radiation detector system based on SiC-based microstrip + LYSO scintillation crystal provided by the present invention comprises: SiC microstrip detector, LYSO crystal, SiPM, fixture, power supply assembly, SiPM readout PCB board, ASIC chip, ASIC peripheral circuit board, FPGA functional module, metal shielding box, and host computer. The SiPM is pasted behind the LYSO crystal using silica gel; at least four layers of SiC microstrip detectors are vertically installed above the LYSO crystal in pairs, and are all aligned with the LYSO crystal to form a telescope structure together, and serve as the incident end of radiation particle detection, the SiC-based microstrip detector serves as the first-level energy detection unit, and the LYSO scintillation crystal serves as the second-level energy detection unit. The ASIC chip and peripheral circuit board in the back-end electronics are used to collect the number of electron-hole pairs generated by the multiple SiC detector microstrips of the first-level energy detection unit after irradiation, calculate the number of charges, and amplify and collect and hold signals; the ASIC chip peripheral circuit board is used to provide working voltage, filtering, protection of the ASIC chip, and further isolation of digital / analog signals for the ASIC chip and SiC microstrip detectors, and at the same time connect the FPGA function module through connectors and PCB traces to achieve multi-channel readout of the detector signal. One end of the FPGA module is connected to the ASIC peripheral circuit board and the SiPM readout PCB board, and the dE collected by the two-stage energy detection unit is collected by the ASIC chip peripheral circuit board. i and E to compare the types of particles, collect the position information of the energy deposition generated by the SiC microstrips at different positions of different layers when the particles pass through the SiC detector at the time of incidence, determine the incident angle of the particles by calculation, and obtain the path of the particles through the energy response of the microstrips. At the same time, one end of the FPGA module adapts to the input signal range of the high-speed ADC; controls the operation of the A / D conversion circuit, continuously samples under the control of the sampling clock, converts the analog signal into a continuous data stream, and digitizes each strip detector in the same way, completes the data stream input and output design, and realizes the data transmission and command response functions.

[0053] The innovation of the present invention lies in the design of a telescope structure scheme using a multi-layer SiC microstrip detector + LYSO crystal. First, at the top of the fixed device, the SiC detector end adopts a multi-layer structure as the first-level energy detection unit, and through the adjacent vertical microstrip structure, when the particle is incident, the response of the different microstrip positions hit can determine the exact position, angle, time, and path of the particle incident. A LYSO scintillation crystal is placed 4 cm below the SiC detector as the second-level energy detection unit. When the particle passes through the SiC detector end, it will continue to be incident into the LYSO crystal. The fluorescent signal generated by it is converted into an electrical signal through the SiPM, and the type of the particle is judged through the energy spectrum response of the two-level energy detection unit. Secondly, the ASIC+FPGA readout system is used in the electronic readout, which greatly improves the volume, power consumption, convenience, stability, etc. of the device, and can simultaneously process multiple signals of the SiC microstrip detector and the LYSO crystal. The present invention can realize the determination of the position, angle, time, path and type of incident particles, optimize the convenience of the readout device, improve the particle detection efficiency, reduce the impact of experimental environment changes on the stability of the experimental system, and realize multi-channel signal readout in more complex experimental environments and with a wide variety of particles, providing a more stable, efficient and convenient readout system. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 This is a structural diagram of a compact radiation detector system based on SiC-based microstrips + LYSO scintillation crystals.

[0055] Figure 2 A structural block diagram of the device.

[0056] Figure 3 The diagram shows the placement of the SiC detector, a top view, and the dimensions of the LYSO crystal.

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

[0058] (b) is a schematic diagram of the placement of two adjacent layers of SiC detector microstrips.

[0059] (c) Schematic diagram of the size of LYSO crystals.

[0060] Explanation of the 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-host computer PC terminal; 11-fixing device. DETAILED DESCRIPTION

[0061] The present invention is further described in detail below in conjunction with the accompanying drawings.

[0062] Example 1

[0063] like Figure 1 As shown, a compact radiation detector system based on SiC-based microstrip + LYSO scintillation crystal comprises a SiC-based microstrip detector (1), a LYSO scintillation crystal (2), a SiPM (3), a power supply component (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 a host computer (10). The specific connection method of this embodiment is as follows:

[0064] A polyimide double-sided aluminum-plated window is set on one side of the particle incident end. 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-based microstrip detector (1) is fixed on a light-tightly designed fixing device (11), the spacing between the SiC microstrip detectors is 2 cm, and the microstrips of two adjacent layers are perpendicular to each other, the distance between the top SiC-based microstrip detector and the polyimide window is 15 mm, and the distance between the bottom SiC-based microstrip detector and the LYSO scintillation crystal is 4 cm. The connector at one end is led out with a cable for connecting a power module (4) and an ASIC peripheral circuit board (7) to provide a bias operating voltage for the SiC microstrip and signal readout.

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

[0067] The LYSO scintillation crystal (2) is located 4 cm below the SiC-based microstrip detector (1), and the outside of the LYSO scintillation crystal (2) needs to be wrapped with a reflective 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 patch welding, and its input end is led out to the connector end through PCB wiring and connected to the connector of the SiC-based microstrip detector (1) through a cable.

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

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

[0071] One end of the FPGA module (8) is connected to the ASIC peripheral circuit board (7). The functions of the FPGA module include: logic selection function, address information of hit bars and case classification and packaging storage function, as well as self-detection, mode switching, acquisition control, gain correction and configuration data. The upper computer controls it to ensure the validity, accuracy and flexibility of the detection data extracted by the electronic system.

[0072] The ASIC chip (6), the ASIC peripheral circuit board (7), the SiPM readout PCB board (5), and the FPGA functional module (8) are all installed inside the metal shielding box to reduce electromagnetic interference in the environment and prevent the effective signal from being unable to be collected due to excessive noise.

[0073] After particle irradiation, the SiC microstrip detector (1) will be ionized to generate electron-hole pairs. Under the action of bias voltage, they will be quickly separated by the electric field to be collected by the electrode, generating a signal response and collected and processed by the ASIC chip (6). In the four-layer SiC microstrip detector structure, it is difficult for uncharged particles to deposit energy in the first layer. They may deposit energy in the subsequent layers of SiC microstrip detectors or enter the LYSO scintillation crystal. Therefore, when selecting the trigger threshold, the signal threshold of the subsequent layers will be set differently from the first layer to determine whether the particles are charged. The electrons, alpha particles and protons among the charged particles may all have deposited energy in the device, but the deposited energy of the electrons will decrease layer by layer, so they can also be distinguished.

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

[0075] The charge-sensitive preamplifier integrated inside the ASIC chip (6) is divided into two types: fast and slow shaping amplifiers. The fast shaping amplifier forms a trigger signal pulse generator from the input discriminator and transmits the amplified signal to the rear slow shaping amplifier, which is beneficial for the holding circuit of the slow shaping amplifier to extract the signal amplitude information signal data; and then the ADC converts the analog signal into a digital signal.

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

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

[0078] After passing through the end of the SiC detector (1), the particle will continue to be incident into the LYSO scintillation crystal (2). At this time, the crystal converts the incident particle deposition energy into a fluorescent signal. The size of the fluorescent signal is proportional to the energy of the incident particle. The crystal is wrapped with reflective material all around, and one side is attached to the SiPM. At this time, the SiPM collects the fluorescent signal of the crystal and converts it into a current signal output. The SiPM is essentially a pn junction, which works in a reverse bias state. When the incident photon irradiates its surface, an electron-hole pair is generated. This process is similar to that of a photodiode. At this time, the current value I of the two-stage output is in The back-end amplifier 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 resistor of the transimpedance amplifier.

[0079] The host PC configures the FPGA through Verilog language compilation, thereby generating a readout control signal and controlling the operation of the A / D conversion circuit. The A / D converter continuously samples under the control of the sampling clock and converts the analog signal into a continuous data stream to ensure that data is not lost even at high current intensity. Each strip detector is digitized in the same way.

[0080] The required bias voltage of the SiC microstrip detector (1) is -40V;

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

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

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

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

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

[0086] The FPGA driver is compiled, simulated and burned using Vivado software, and the programming language is Veirlog.

[0087] The read data information such as position, information, energy spectrum, etc. are collected by FPGA and then collected, displayed and controlled by the host computer software written by PYQT software on the host computer PC (10).

[0088] The specific implementation methods described above further illustrate the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above examples are merely illustrative of the present invention and do not constitute a limitation on the protection scope of the present invention. All designs that are the same or similar to the present invention belong to the protection scope of the present invention.

Claims

1. A compact radiation detector system, characterized in that: It includes a semi-enclosed fixture, SiPM, a shielding box and a host computer; the fixture is provided with a first-level energy detection unit and a second-level energy detection unit, and the shielding box is provided with a control unit and an ASIC chip; The first-stage energy detection unit is used to generate energy deposition on the charged particles and send it to the control unit; the deposited energy is recorded as dE; 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; wherein the sum of the residual energy of the charged particles and the energy of the uncharged particles is denoted as E; 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 inside the first-stage energy detection unit after being irradiated by particles, and send it to the control unit; The control unit is used to perform data exchange with the host computer; The host computer is used to monitor and control the signal output by the control unit, and to identify the incident path, trajectory, and direction of the charged particles according to the deposited energy dE output by the first-level energy detection unit, and to judge the type of particles according to dE and E.

2. The compact radiation detector system according to claim 1, characterized in that The first-stage energy detection unit is a telescope structure, including at least four layers of SiC-based semiconductor detectors, which are used to produce different energy depositions on incident particles; Among them, the microstrips in two adjacent layers of SiC-based semiconductor detectors are vertical.

3. The compact radiation detector system according to claim 2, characterized in that The second-level 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.

4. The compact radiation detector system according to claim 2 or 3, 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.

5. The compact radiation detector system according to claim 3, characterized in that The LYSO scintillation crystal is an inorganic scintillator, and its volume is 3cm*3cm*3cm.

6. The compact radiation detector system according to claim 2 or 3, characterized in that The method for identifying the incident path, trajectory and direction of charged particles according to the deposited energy dE output by the first-level energy detection unit is as follows: when a 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 charged particles of the current particle are determined by two sets of coordinates (x1, y1) and (x2, y2).

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