Dual-sided SiPM array integrated αβγ detector and detection method

Abstract

The application provides a double-sided SiPM array integrated alpha beta gamma detector and a detection method, and relates to the technical field of radiation monitoring sensors. The detector comprises a circuit board, a front pixelated scintillator and a back scintillator, a front SiPM array, a back SiPM array and a processor. The circuit board blocks alpha and beta particles and allows gamma rays to penetrate. The front scintillator and the back scintillator are arranged on the two sides of the circuit board and are respectively coupled and welded to the SiPM array on the two sides of the circuit board. The front scintillator is a pixelated scintillator and corresponds to the first detection unit one by one. The processor counts the count rate distribution of each detection unit of the front SiPM array to locate the alpha / beta pollution source, and corrects the beta count rate according to the gamma count rate output by the back SiPM array to eliminate gamma crosstalk. The application is beneficial to the lightweight of handheld devices, the correction does not depend on material attenuation parameters, and the pollution source hot spot can be accurately located.

Description

Technical Field

[0001] This invention relates to the field of radiation monitoring and sensing technology, and in particular to an integrated αβγ detector using a double-sided silicon photomultiplier (SiPM) array. Background Technology

[0002] Radioactive surface contamination monitoring is a crucial aspect of nuclear facility safety, environmental radiation monitoring, and nuclear emergency response. Alpha, beta, and gamma rays differ in their penetrating power and biological effects, requiring separate measurements of their activity or dose. Portable surface contamination measuring instruments typically employ a zinc-silver sulfide plastic composite scintillator coupled to a photomultiplier tube (PMT) or silicon PMT, utilizing the differences in pulse amplitude and pulse width generated by alpha and beta particles within the scintillator to distinguish between alpha and beta signals. However, this scintillator has extremely low detection efficiency for gamma rays. To compensate for this deficiency, existing instruments often incorporate an additional Geiger-Müller counter (GM) tube as a separate gamma detector, forming a dual-detector scheme combining the scintillator and the GM tube. However, this dual-detector scheme suffers from problems such as complex structure, large size, inconsistent measurement positions, and the inability to effectively correct for beta measurements due to gamma field interference.

[0003] Currently, to address the aforementioned issues of complex structure and large size, a scheme employing layered scintillators and independent photodetectors has emerged. In this scheme, the upper layer is a stacked scintillator for measuring alpha and beta rays, while the lower layer is a plastic scintillator for measuring gamma rays, separated by a reflector. Each layer outputs signals via independent optical fibers and photomultiplier tubes (or silicon photomultiplier tubes). However, this scheme requires separate optical fibers, photoelectric conversion devices, and signal processing channels for each layer, resulting in a large and heavy detector, which is detrimental to the lightweight design of handheld devices. While the lower layer's gamma count corrects gamma interference in the upper layer's beta channel, the correction formula depends on the scintillator's attenuation length, making it reliant on unstable parameters. Furthermore, it only outputs the total count and cannot determine the specific distribution of contaminant sources below the detector probe, making it difficult to quickly locate hotspots when surface contamination is uneven. Summary of the Invention

[0004] The purpose of this invention is to provide an integrated αβγ detector and detection method for a dual-sided SiPM array, which solves the problems of existing technologies being unfavorable for the lightweight design of handheld devices, relying on unstable parameters for correction formulas, and being difficult to quickly locate hotspots when surface contamination is uneven.

[0005] To address the aforementioned technical problems, the embodiments of the present invention provide the following technical solutions: The first aspect of this invention provides a dual-sided SiPM array integrated αβγ detector, comprising: The circuit board is thick enough to block alpha particles and beta particles with energies below 0.6 MeV, while allowing gamma rays to penetrate. A front scintillator, disposed on one side of the circuit board, is used to generate a first scintillator light in response to incident rays; the front scintillator is a pixelated scintillator; a back scintillator, disposed on the other side of the circuit board, is used to generate a second scintillator light in response to γ ​​rays penetrating the circuit board. The front-side SiPM array is soldered to one side of the circuit board and optically coupled to the front-side scintillator. The front-side SiPM array includes multiple first detection units; each first detection unit is used to convert the first scintillating light into a first electrical signal and output the first electrical signal. The back-side SiPM array is soldered to the other side of the circuit board and optically coupled to the back-side scintillator. The back-side SiPM array includes multiple second detection units; each second detection unit is used to convert the second scintillator light into a second electrical signal and output the second electrical signal. The processor, mounted on a circuit board and coupled to the front and back SiPM arrays, is used to receive the first electrical signal output by each first detection unit and the second electrical signal output by each second detection unit; and to statistically analyze the count rate distribution of the first electrical signal output by each first detection unit, determine the location of the α pollution source and / or β pollution source based on the count rate distribution; determine the γ count based on the second electrical signal, and correct the β count based on the γ count. The circuit board serves as both the mechanical support and electrical connection carrier for both the front-side SiPM array and the back-side SiPM array.

[0006] A second aspect of the present invention provides a detection method for a dual-sided SiPM array integrated αβγ detector, comprising: In calibration mode, the detector is irradiated with gamma radiation sources that are free of alpha and beta contamination. The count rate of the front beta channel and the count rate of the back gamma channel are obtained. The count rate of the front beta channel is divided by the count rate of the back gamma channel to calculate the calibration coefficient, and the calibration coefficient is stored. In measurement mode, for each pulse of the first electrical signal output by the front SiPM array, it is determined whether the amplitude of the current pulse is greater than a preset amplitude threshold and whether the width of the current pulse is greater than a preset width threshold. If so, the current pulse is determined as an α pulse and the α count is accumulated. If not, the current pulse is determined as a non-α pulse, the non-α pulse is accumulated as a β count, and the count rate distribution of each first detection unit in the front SiPM array is recorded. The thickness of the front scintillator is 0.3mm to 1.0mm, and the front scintillator is a plastic scintillator or a zinc sulfide silver plastic composite scintillator. Based on the second electrical signal output from the back-side SiPM array, each pulse in the second electrical signal is accumulated as a γ count; Based on the β hair count and γ count, the calibration coefficients pre-stored in the detector are called to perform a linear correction calculation on the β hair count to obtain the true β count; The total count of the front-side SiPM array in the current cycle is counted, and it is determined whether the total count is greater than a preset threshold. If so, the cell coordinates where the count rate peak is located are determined according to the count rate distribution. The cell coordinates are used as the projection position of the contamination source on the detector incident surface, and the projection position and the actual β count are output. If not, the valid projection position of the previous output is maintained, or a prompt message indicating insufficient count is output.

[0007] Compared to existing technologies, the dual-sided SiPM array integrated αβγ detector provided by this invention includes a circuit board, the thickness of which is sufficient to block α particles and β particles with energies below 0.6 MeV, while allowing γ rays to penetrate; a front scintillator, disposed on one side of the circuit board, for generating a first scintillator light in response to incident rays; the front scintillator is a pixelated scintillator; a back scintillator, disposed on the other side of the circuit board, for generating a second scintillator light in response to γ ​​rays penetrating the circuit board; a front SiPM array, soldered to one side of the circuit board and optically coupled to the front scintillator, the front SiPM array including multiple first detection units; each first detection unit is used to convert the first scintillator light into a first electrical signal and output the first electrical signal; and a back SiPM array, soldered to the circuit board. On the other side of the board, it is optically coupled to the back-side scintillator. The back-side SiPM array includes multiple second detection units. Each second detection unit converts the second scintillating light into a second electrical signal and outputs the second electrical signal. A processor, mounted on the board and coupled to both the front and back SiPM arrays, receives the first electrical signals output by each first detection unit and the second electrical signals output by each second detection unit. It also calculates the count rate distribution of the first electrical signals output by each first detection unit, determines the location of α and / or β contaminant sources based on the count rate distribution, determines the γ count based on the second electrical signal, and corrects the β count based on the γ count. The board serves as both the mechanical support and electrical connection carrier for both the front and back SiPM arrays. This integration of the front and back SiPM arrays onto the same board creates an integrated double-sided SiPM array structure, eliminating the need for independent optical fibers and multiple photoelectric conversion devices, significantly reducing the detector's size and contributing to the lightweight design of handheld devices. The thickness of the board blocks α and β particles, allowing only γ rays to penetrate, thus eliminating the need for correction operations to rely on the material's attenuation parameters. By independently outputting counts from each detection unit of the front-side SiPM array and forming a count rate distribution, the precise location of the contamination source below the probe can be determined when the surface contamination is uneven, thus enabling rapid hotspot localization. Attached Figure Description

[0008] The above and other objects, features, and advantages of exemplary embodiments of the present invention will become readily apparent upon reading the following detailed description with reference to the accompanying drawings. In the drawings, several embodiments of the invention are illustrated by way of example and not limitation, with the same or corresponding reference numerals denoteing the same or corresponding parts, wherein: Figure 1 A schematic diagram of the layered structure of an integrated αβγ detector with a dual-sided SiPM array is shown. Figure 2 A schematic block diagram of a dual-channel analog front-end circuit is shown. Figure 3 The schematic diagram illustrates the detection method flow of an integrated αβγ detector with a dual-sided SiPM array. Figure 1 ; Figure 4 The schematic diagram illustrates the detection method flow of an integrated αβγ detector with a dual-sided SiPM array. Figure 2 .

[0009] Explanation of reference numerals in the attached figures: 1. Circuit board; 2. Front scintillator; 3. Back scintillator; 4. Front SiPM array; 5. Back SiPM array. Detailed Implementation

[0010] Exemplary embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the invention and to fully convey the scope of the invention to those skilled in the art.

[0011] It should be noted that, unless otherwise stated, the technical or scientific terms used in this invention should have the ordinary meaning as understood by one of ordinary skill in the art.

[0012] The methods described in the embodiments of the present invention will be explained in detail below.

[0013] Figure 1 A schematic diagram illustrating the layered structure of the integrated αβγ detector with a dual-sided SiPM array in an embodiment of the present invention is shown below. Figure 1 As shown, the dual-sided SiPM array integrated αβγ detector may include: Circuit board 1, the thickness of circuit board 1 is sufficient to block alpha particles and beta particles with energies below 0.6 MeV, while allowing gamma rays to penetrate; A front scintillator 2 is disposed on one side of the circuit board 1 and is used to generate a first scintillating light in response to an incident ray; the front scintillator 2 is a pixelated scintillator. The back scintillator 3 is disposed on the other side of the circuit board 1 and is used to generate a second scintillator light in response to γ ​​rays penetrating the circuit board 1; The front-side SiPM array 4 is soldered to one side of the circuit board 1 and optically coupled to the front-side scintillator 2. The front-side SiPM array 4 includes multiple first detection units; each first detection unit is used to convert the first scintillating light into a first electrical signal and output the first electrical signal. The back-side SiPM array 5 is soldered to the other side of the circuit board 1 and optically coupled to the back-side scintillator 3. The back-side SiPM array 5 includes multiple second detection units; each second detection unit is used to convert the second scintillating light into a second electrical signal and output the second electrical signal. The processor, mounted on circuit board 1 and coupled to the front SiPM array 4 and the back SiPM array 5, is used to receive the first electrical signal output by each first detection unit and the second electrical signal output by each second detection unit; and to statistically analyze the count rate distribution of the first electrical signal output by each first detection unit, and determine the location of the α pollution source and / or β pollution source based on the count rate distribution; and to determine the γ count based on the second electrical signal, and to correct the β count based on the γ count. In this circuit board 1, the mechanical support and electrical connection carrier of the front SiPM array 4 and the back SiPM array 5 are simultaneously used.

[0014] In this embodiment, the dual-sided SiPM array integrated αβγ detector further includes a first light-blocking aluminum film and a second light-blocking aluminum film; A first light-blocking aluminum film is disposed on the incident side surface of the front scintillator 2; The second light-blocking aluminum film is disposed on the side of the first light-blocking aluminum film that is away from the front scintillator 2; The first and second light-blocking aluminum films are used to shield ambient natural light.

[0015] Specifically, the dual-sided SiPM array integrated αβγ detector may also include a sealed light-shielding shell for housing the circuit board 1, the front scintillator 2, the back scintillator 3, the front SiPM array 4, the back SiPM array 5, the first light-shielding aluminum film and the second light-shielding aluminum film, and shielding external ambient light.

[0016] To prevent ambient light from entering the detector from the side or through pinholes in the aluminum film, the first and second light-shielding aluminum films, the front scintillator 2, the front SiPM array 4, the circuit board 1, the back SiPM array 5, and the back scintillator 3 are all encapsulated within a sealed light-shielding housing. This sealed light-shielding housing can be made of metal (such as aluminum alloy) or opaque plastic. To improve the collection efficiency of scintillating light and ensure the uniformity of response of edge pixels, the inner surface of the housing should be set as a high-reflectivity layer, such as aluminum plating, attaching an enhanced specular reflector (ESR) reflective film, coating with BaSO4, or white ink. An incident window is provided on the sealed light-shielding housing at a position corresponding to the incident side of the front scintillator 2. This incident window is covered by the first and second light-shielding aluminum films, ensuring a seamless seal between the edge of the incident window and the housing. Conductive rubber gaskets or optical sealant can be added to the seams of the sealed light-shielding housing to achieve complete light blocking and ambient light shielding. The combination of the sealed light-shielding shell and the double-layer light-shielding aluminum film ensures that the SiPM array can work normally under ambient light without generating additional noise. At the same time, the highly reflective inner surface can maximize light collection efficiency, improve detection sensitivity and positioning uniformity.

[0017] Specifically, the dual-sided SiPM array integrated αβγ detector of the present invention adopts a sandwich stacked structure, which includes the following layers from the incident surface (i.e., the top) to the back surface (i.e., the bottom): a first light-shielding aluminum film, a second light-shielding aluminum film, a pixelated front scintillator 2, a front SiPM array 4, a circuit board 1, a back SiPM array 5, and a back scintillator 3. The front scintillator 2 is cut or molded into a pixel array that corresponds one-to-one with the detection unit of the front SiPM array 4. Each pixel array independently generates scintillating light, and optical isolation (such as filling the pixel gaps with white reflective material) prevents crosstalk between pixels, thereby ensuring that the scintillating light received by each first detection unit comes only from the scintillator pixel directly above it.

[0018] The first and second light-shielding aluminum films are located on the outermost layer of this double-sided SiPM array integrated αβγ detector, closely attached to the upper surface of the front scintillator 2. These two layers of light-shielding aluminum films shield ambient natural light, preventing external light from entering the front scintillator 2 and the back scintillator 3 and generating false trigger signals. The thickness of the two light-shielding aluminum films is in the micrometer range, with each layer being 2.4 μm thick, for a total thickness of approximately 4.8 μm. It should be noted that the number of light-shielding aluminum film layers is not limited to two; a single layer can also achieve basic light-shielding functionality. However, using two layers further reduces the risk of light leakage due to pinhole defects, improving reliability. The total thickness of these two light-shielding aluminum films has minimal blocking effect on α and β particles; the range of α particles in aluminum is approximately several micrometers to tens of micrometers, which depends on energy, and the 2.4 μm thick light-shielding aluminum film causes only negligible energy loss; β particles have stronger penetrating power and are almost unaffected. γ rays are completely unaffected by the aluminum films. Therefore, the introduction of the light-blocking aluminum film does not affect the detector's detection efficiency for alpha particles, beta particles, and gamma rays.

[0019] In this embodiment, the front scintillator 2 is a zinc sulfide silver plastic composite scintillator or a plastic scintillator, and the thickness of the front scintillator 2 is 0.3 mm to 1.0 mm; the zinc sulfide silver plastic composite scintillator is used to detect alpha and beta rays, and the plastic scintillator is used to detect gamma rays.

[0020] Specifically, the front scintillator 2 uses a zinc silver sulfide (ZnS(Ag)) plastic composite scintillator to simultaneously detect alpha and beta rays, thus achieving the first operating mode. The first operating mode refers to the mode that detects all three types of rays: alpha, beta, and gamma rays.

[0021] The front scintillator 2 can also be a pure plastic scintillator for detecting beta rays, thus achieving the second operating mode. The second operating mode refers to the mode that detects only beta and gamma rays.

[0022] The preferred thickness of the front scintillator 2 is 0.5 mm. To achieve pixelation, laser cutting or precision mechanical cutting can be used to divide the large scintillator into independent pixels with the same spacing as the SiPM array unit. The pixel size is slightly smaller than the SiPM photosensitive surface (for example, if the SiPM unit spacing is 2 mm, the scintillator pixel size is 1.8 mm × 1.8 mm). White reflective material (such as TiO2 epoxy resin) is filled between the pixels to isolate optical crosstalk. The top surface of the front scintillator 2 is in direct contact with the second light-shielding aluminum film, and the bottom surface of the front scintillator 2 is bonded to the photosensitive surface of the underlying silicon photomultiplier tube (SiPM) through an optical coupling agent (such as silicone grease). This front scintillator 2 converts α particles, β particles, and γ rays that penetrate the two layers of light-shielding aluminum film into first scintillating light.

[0023] In another embodiment, to further improve the α / β positioning accuracy, a thin light guide (e.g., a 0.3 mm thick transparent silicone layer) can be added between the front scintillator 2 and the front SiPM array 4. This allows the scintillating light to diffuse appropriately and cover 2-3 SiPM units, thereby achieving a positioning resolution superior to that of a pixel using the centroid method (calculating sub-pixel coordinates weighted by the count rate of each unit). The thickness of the thin light guide should balance light collection efficiency and crosstalk suppression; the specific value can be determined by those skilled in the art based on the adaptability of the unit spacing and scintillator thickness.

[0024] In this embodiment, circuit board 1 is a printed circuit board with a thickness ≥1.0mm to block common alpha and beta particles (beta particles have an energy of less than 0.6MeV).

[0025] In this embodiment, the front SiPM array 4 and / or the back SiPM array 5 are 4×4 arrays, 8×8 arrays, or 16×16 arrays, and the cell spacing of the front SiPM array 4 and / or the back SiPM array 5 is 1mm to 3mm.

[0026] Specifically, this involves double-sided SiPM soldering on printed circuit boards (PCBs). Flame Retardant 4 (FR4) or other PCBs with sufficient mechanical strength and insulation properties are used. The thickness of the PCB is ≥1.0 mm, preferably 1 mm. This thickness is sufficient to block common alpha and beta particles (beta particles have energies below 0.6 MeV), preventing them from penetrating to the back side. Based on mass blocking ability calculations, the areal density of 1.0 mm thick FR4 (density approximately 1.8 g / cm³) is approximately 0.18 g / cm². For beta particles with energies below 0.6 MeV, their range is less than 0.18 g / cm², thus effectively blocking them. Higher-energy beta particles (a very small number of nuclides) may partially penetrate, but this is negligible in typical surface contamination monitoring scenarios. Gamma rays, however, have strong penetrating power and can pass through the PCB.

[0027] The front-side SiPM array 4 is soldered to the front side of the circuit board 1 with the photosensitive side facing upwards and is optically coupled to the front-side scintillator 2. The front-side SiPM array 4 is in array form, such as a 4×4 array, an 8×8 array, or a 16×16 array. Each first detection unit in the front-side SiPM array 4 independently outputs a first electrical signal to detect the first scintillating light generated by the front-side scintillator 2 and to locate the pollution source.

[0028] The back-side SiPM array 5 is soldered to the back side of the circuit board 1 with the photosensitive side facing down and is optically coupled to the back-side scintillator 3. The back-side SiPM array 5 is also in array form, and each second detection unit in the back-side SiPM array 5 independently outputs a second electrical signal to detect the second scintillator light generated by the back-side scintillator 3.

[0029] The front-side SiPM array 4 and the back-side SiPM array 5 share electrodes and a bias network. Specifically, the cathodes (or anodes) of the front-side SiPM array 4 and the back-side SiPM array 5 are connected to the same bias power supply through internal PCB wiring, saving external circuitry. The output of the first electrical signal corresponding to each first detection unit in the front-side SiPM array 4 and the output of the second electrical signal corresponding to each second detection unit in the back-side SiPM array 5 are routed on independent signal lines, without interfering with each other.

[0030] The printed circuit board (PCB) features signal lead-out pads or miniature connectors, such as 1.27mm pitch headers, flexible printed circuit (FPC) connectors, or sub-miniature version A (SMA) coaxial connectors. The electrical signals output from the front-side SiPM array 4 and the rear-side SiPM array 5 are transmitted to separate signal processing boards via independent shielded cables (such as 50Ω coaxial cables or miniature coaxial cables). These signal processing boards include preamplifiers, shaping circuitry, analog-to-digital converters, and logic decision units, where the logic decision units are field-programmable gate arrays (FPGAs) or microcontrollers. Using coaxial cables or twisted-pair shielded wires effectively reduces external electromagnetic interference and ensures the fidelity of the pulse signals. Furthermore, the bias power supply (26V–30V) and signal reference ground can be supplied from the signal processing board to the PCB via the same multi-core cable, or generated separately at the detector end and distributed through the PCB's internal power supply network.

[0031] In this embodiment, a temperature sensor is also integrated on the circuit board 1. The temperature sensor is used to monitor the ambient temperature and perform temperature compensation on the gain of the front SiPM array 4 and / or the back SiPM array 5 according to the ambient temperature. And / or, the circuit board 1 is also provided with an coded resistor, which is used to identify the type of the front scintillator 2 and automatically switch the working mode of the detector according to the type.

[0032] Specifically, circuit board 1 provides both the power supply voltage and the signal circuit for the SiPM. The bias voltage of the power supply voltage is 26V to 30V.

[0033] In this embodiment, the back scintillator 3 is a plastic scintillator, and the thickness of the back scintillator 3 is 5mm to 10mm.

[0034] Specifically, the back-side scintillator 3 is a pure plastic scintillator, such as EJ-200 or BC-408, with a continuous flat plate structure (non-pixelated) and a preferred thickness of 8 mm. The top surface of the back-side scintillator 3 is bonded to the photosensitive surface of the back-side SiPM array 5 via an optical coupling agent. Since alpha particles and beta particles with energies below 0.6 MeV are blocked by the intermediate circuit board 1 (higher-energy beta particles may partially penetrate, but this is negligible in conventional measurements), the back-side scintillator 3 only receives γ rays that penetrate the circuit board 1 and converts them into second scintillating light, which is then detected by the back-side SiPM array 5. The reason for using a continuous flat plate structure instead of a pixelated one is that the flat plate structure simplifies the process, reduces costs, and ensures light collection efficiency.

[0035] See Figure 1 As shown, alpha particles penetrate two layers of light-shielding aluminum film with almost no energy loss, and then enter the front scintillator 2, where all energy is deposited in the shallow layer to generate the first scintillating light, which is detected by the front SiPM array 4. Alpha particles cannot penetrate the printed circuit board, so the back SiPM array 5 has no signal.

[0036] β particles penetrate two layers of light-shielding aluminum film and then enter the front scintillator 2, possibly penetrating the entire thickness of the front scintillator 2, generating the first scintillation light, which is detected by the front SiPM array 4; β particles are blocked by the printed circuit board, and the back SiPM array 5 has no signal.

[0037] Gamma rays penetrate two layers of light-shielding aluminum film, then pass through the front scintillator 2, producing Compton scattering or photoelectric effect, with some energy deposited to generate the first scintillator light, which is detected by the front SiPM array 4. Gamma rays also penetrate the printed circuit board, enter the back scintillator 3, deposit the remaining energy, and generate the second scintillator light, which is detected by the back SiPM array 5. Therefore, gamma rays generate electrical signals on both the front and back SiPM arrays, and the two electrical signals are temporally correlated. The time difference between the two signals originates from light propagation and electronic delay.

[0038] The electronic system used in the detector of this invention is divided into a front signal channel and a back signal channel. The two signal channels share the same signal processing board, which is connected to the front SiPM array 4 and the back SiPM array 5 on the detector's printed circuit board via shielded cables. This signal processing board integrates dual-channel analog front-end circuitry. Figure 2 A schematic block diagram of a dual-channel analog front-end circuit is shown below. Figure 2As shown, in the front signal channel, the weak current signal output from the front SiPM array 4 undergoes the following processing: First, it is fed into a preamplifier to convert the weak current signal into a voltage signal and perform a first-stage amplification. The preamplifier is a transimpedance amplifier with a gain of approximately 10kΩ. Then, it is further amplified by a second-stage main amplifier to a suitable amplitude of 0V to 2V. Subsequently, the amplified pulse is filtered and shaped by a signal shaping circuit to improve the signal-to-noise ratio and reduce pulse width fluctuations, facilitating subsequent amplitude and width measurements. This signal shaping circuit can be a CR-RC shaping circuit. The shaped pulse is then fed into a pulse width and amplitude discriminator, which is a comparator. Its threshold is typically adjustable, and the comparator outputs a trigger signal. Trigf Simultaneously, the pulse width is measured using the duration of the high-level output of the comparator or a dedicated pulse width measurement circuit; the pulse width is the full width at half maximum (FWHM). The amplitude value can also be quantized using a peak-hold circuit in conjunction with an analog-to-digital converter (ADC). The ADC parameters for quantization are 12-bit resolution and a sampling rate of at least 100MHz. The final outputs are an α signal and a β signal containing γ interference. The α signal has a high amplitude and long width, while the β signal has a low amplitude and short width, denoted as the β-signal.

[0039] In the rear signal channel, the current signal output from the rear SiPM array 5 undergoes the following processing: First, it is fed into a preamplifier to convert the current signal into a voltage signal, ensuring the gain matches that of the front signal channel; then, the voltage signal is amplified by a second-stage main amplifier to output a pulse; subsequently, the output pulse is shaped by a signal shaping circuit to ensure a regular pulse shape for reliable triggering. The shaped pulse is then directly used as a γ signal, fed into a counter or comparator to generate a trigger signal. Trigb The back-side signal channel typically does not require amplitude / width discrimination because all pulses arriving at the back-side originate from gamma rays.

[0040] The shared circuitry for the front and rear signal channels includes a high-voltage power supply, a temperature compensation circuit, and a signal processing unit. Specifically, the high-voltage power supply provides a stable bias voltage to the SiPM array, with soft-start and overcurrent protection; the stable bias voltage is 26V–30V. The optional temperature compensation circuit monitors the ambient temperature and automatically adjusts the bias voltage or amplifier gain of the SiPM array to stabilize the gain. The signal processing unit receives the trigger signal from the front signal channel. Trigf Amplitude value, width value, and trigger signal of the back signal channel. Trigb It performs logical decision-making and correction operations, wherein the signal processing unit is an FPGA or a microcontroller.

[0041] The detector used in the detection method of this invention can operate in two modes by replacing the front scintillator 2.

[0042] The first operating mode is the αβγ full measurement mode. In this first operating mode, a zinc sulfide silver plastic composite scintillator is installed on the front, enabling the full α pulse and β pulse discrimination function, β count correction function, and γ count function, and finally outputting the α count, true β count, and γ count.

[0043] The second operating mode is the dedicated β / γ mode. In this mode, a pure plastic scintillator is installed on the front. Because the signal amplitude generated by alpha particles in this pure plastic scintillator is extremely low and cannot trigger the threshold, all pulses in the front signal channel originate only from β particles and γ rays, and are all judged as β counts. The same linear correction formula is still used, but the calibration coefficients corresponding to this pure plastic scintillator are automatically loaded, and the final output is the true β count and γ count, but not the α count.

[0044] Switching between operating modes can be achieved through software settings or hardware detection. After switching operating modes, the preset amplitude threshold, preset width threshold, and the invoked calibration coefficients are automatically adjusted.

[0045] Based on the above Figure 1As can be seen from the implementation, the dual-sided SiPM array integrated αβγ detector of this embodiment includes a circuit board 1. The thickness of the circuit board 1 is sufficient to block α particles and β particles while allowing γ rays to penetrate. A front scintillator 2 is disposed on one side of the circuit board 1 and is used to generate a first scintillator light in response to incident rays. The front scintillator 2 is a pixelated scintillator. A back scintillator 3 is disposed on the other side of the circuit board 1 and is used to generate a second scintillator light in response to γ ​​rays penetrating the circuit board 1. A front SiPM array 4 is soldered to one side of the circuit board 1 and optically coupled to the front scintillator 2. The front SiPM array 4 includes multiple first detection units. Each first detection unit is used to convert the first scintillator light into a first electrical signal and output the first electrical signal. A back SiPM array 5 is soldered to the circuit board 1. On the other side, it is optically coupled to the back scintillator 3. The back SiPM array 5 includes multiple second detection units. Each second detection unit is used to convert the second scintillation light into a second electrical signal and output the second electrical signal. A processor, disposed on the circuit board 1 and coupled to the front SiPM array 4 and the back SiPM array 3, is used to receive the first electrical signal output by each first detection unit and the second electrical signal output by each second detection unit; and to statistically analyze the count rate distribution of the first electrical signal output by each first detection unit, determine the location of the α contamination source and / or β contamination source based on the count rate distribution; determine the γ count based on the second electrical signal, and correct the β count based on the γ count. The circuit board 1 serves as both the mechanical support and electrical connection carrier for the front SiPM array 4 and the back SiPM array 5. In this way, the front SiPM array 4 and the back SiPM array 5 are integrated on both sides of the same circuit board 1 to form an integrated double-sided SiPM array structure, eliminating the need for independent optical fibers and multiple photoelectric conversion devices, significantly reducing the size of the detector, and contributing to the lightweight design of handheld devices. The thickness of the circuit board 1 can block α particles and β particles, allowing only γ rays to penetrate, so that the correction operation does not depend on the attenuation parameters of the material. By independently outputting counts from each detection unit of the front-side SiPM array 4 and forming a count rate distribution, the precise location of the contamination source below the probe can be determined when the surface contamination is uneven, thus enabling rapid hotspot localization.

[0046] Based on the same inventive concept, as a realization of the above-mentioned integrated αβγ detector with dual-sided SiPM array, this embodiment of the invention also provides a detection method for the integrated αβγ detector with dual-sided SiPM array. Figure 3 This is a flowchart of the detection method for the integrated αβγ detector with a dual-sided SiPM array in this embodiment of the invention. Figure 1 See Figure 3 As shown, the detection method of this dual-sided SiPM array integrated αβγ detector may include: S301. In calibration mode, the detector is irradiated with a gamma radiation source without α-contamination and β-contamination to obtain the count rate of the front β channel and the count rate of the back γ channel. The count rate of the front β channel is divided by the count rate of the back γ channel to calculate the calibration coefficient and store the calibration coefficient.

[0047] S302. In measurement mode, for each pulse of the first electrical signal output by the front SiPM array 4, determine whether the amplitude of the current pulse is greater than a preset amplitude threshold and whether the width of the current pulse is greater than a preset width threshold. If yes, the current pulse is determined as an α pulse and the α count is accumulated. If no, the current pulse is determined as a non-α pulse, the non-α pulse is accumulated as a β count, and the count rate distribution of each first detection unit in the front SiPM array 4 is recorded.

[0048] The thickness of the front scintillator 2 is 0.3mm to 1.0mm, and the front scintillator 2 is a plastic scintillator or a zinc sulfide silver plastic composite scintillator.

[0049] Specifically, based on the first electrical signal output by the front SiPM array 4, the amplitude and pulse width of each pulse are distinguished. The specific operation of amplitude and pulse width distinction is as follows: if the amplitude of the pulse is greater than the preset amplitude threshold and the width of the pulse is greater than the preset width threshold, it is determined to be an α pulse and the α count is accumulated; otherwise, it is determined to be a non-α pulse.

[0050] Specifically, when the front signal channel generates a trigger signal Trigf At that time, read the amplitude of the pulse. and pulse width The pulse width is half its height and is compared with a preset threshold, which includes a preset amplitude threshold. and preset width threshold ,For example, , .like and If the pulse is positive, it is determined to be an α pulse, and the α counter is incremented by 1; otherwise, it is determined to be a non-α pulse, i.e., a β pulse. β pulses include pulses generated by real β particles and β-like interference pulses generated by γ rays in the front scintillator 2, and the β counter is incremented by 1. This real-time α / β pulse discrimination function is performed on each front pulse in real time, without interacting with the back signal, ensuring high-frequency counting capability.

[0051] S303. Based on the second electrical signal output from the back SiPM array 5, each pulse in the second electrical signal is accumulated as a γ count.

[0052] For the back-side signal channel, since alpha and beta particles are completely blocked by circuit board 1 and cannot reach the back-side scintillator 3, each trigger signal output by the back-side SiPM array 5 is therefore... TrigbEach represents a gamma-ray event. An independent gamma-ray total counter accumulates gamma counts. This accumulation process can be processed in parallel with the frontal pulse discrimination, without occupying the time resources of the frontal signal channel, thus ensuring high-frequency counting capability.

[0053] S304. Based on the β hair count and γ count, the calibration coefficients pre-stored in the detector are called to perform a linear correction calculation on the β hair count to obtain the true β count.

[0054] The calibration coefficients are fixed values ​​obtained through pre-calibration using the target γ-ray source. These calibration coefficients characterize the average number of pulses generated per incident γ-ray in the frontal scintillator 2 and included in the β-hair count. The target γ-ray source is a γ-ray source free from α- and β-contamination.

[0055] Specifically, based on the β hair count and γ count, the calibration coefficients pre-stored in the detector are called to perform a linear correction calculation on the β hair count to obtain the true β count, including: Step A1: Multiply the γ count by the calibration coefficient to obtain the γ disturbance estimate.

[0056] Step A2: The difference between the β count and the γ interference estimate is determined as the true β count.

[0057] Step A3: Determine if the true β count is less than zero. If yes, set the true β count to zero; otherwise, keep the true β count unchanged.

[0058] Specifically, at fixed time intervals For example, in 1 second, read three accumulated values: β hair count. γ count and alpha counting The α count does not require correction. Then, the following linear correction calculation is performed: ; in, For the true beta count, For β hair count, i.e. time interval The total count of β pulses determined in the inner front signal channel, this β pulse count It includes both pulses generated by real beta particles and beta-like interference pulses generated by gamma rays in the frontal scintillator 2. Counting for γ, i.e., time intervals The total count of γ pulses measured by the inner back channel. The calibration coefficient, i.e., the response coefficient of the frontal scintillator 2 to gamma rays, has a range of values ​​of [value missing]. And it was obtained through experimental calibration.

[0059] Calibration coefficients of frontal scintillator 2 for gamma rays is theoretically approximately a constant. This is because for a thin plastic scintillator with a thickness ≤1 mm, γ rays mainly undergo Compton scattering, and the distribution of energy deposition of scattered electrons in the thin layer is relatively flat with the change of incident γ energy. Further theoretical analysis shows that, theoretically, for a plastic scintillator with a thickness d ≤1 mm, the interaction between γ rays and the scintillator is dominated by Compton scattering. Since the scintillator is very thin, the energy deposition of Compton recoil electrons therein changes relatively gently with the incident γ energy (100 keV to 3 MeV), so the calibration coefficient has good stability in the above energy range and the temperature range of -20°C to 50°C. According to the well-known physical principle of Compton scattering in the art and the theory of energy deposition in thin scintillators, it can be deduced that the relative variation of the value is usually within a factor of one (for example, on the order of ±20%), and this accuracy is sufficient to meet the engineering requirements for surface contamination monitoring. Therefore, frequent calibration is not required, and one calibration allows long-term use.

[0060] The theoretical basis for the constancy of the calibration coefficient is as follows: For a plastic scintillator with a thickness d ≤1 mm, the probability of Compton scattering of γ rays is much greater than that of the photoelectric effect. The relationship between the deposited energy E_dep of scattered electrons in the scintillator, the electron range R(e) and the scintillator thickness d is: when R(e) ≥ d, E_dep = d × (dE / dx); when R(e) < d, E_dep = E_e. Since d is very small, for γ rays of 100 keV to 3 MeV, the Compton recoil electron energy E_e is distributed from tens of keV to 2 MeV, and its range R(e) in the scintillator is about 0.1 mm to 2 mm. When E_e is low, R(e) < d, and the electron energy is completely deposited; when E_e is high, R(e) > d, and the electrons pass through the scintillator and only deposit part of the energy. The intersection of the two cases leads to a slow change of the total deposited energy with E_e, so that the probability of generating a triggerable pulse is approximately constant over a wide energy range. According to theoretical estimation, under typical conditions the value variation does not exceed ±20%. Wherein, E is the instantaneous kinetic energy of the particle, x is the path length traveled by the particle in the substance, dE is the average loss of the instantaneous kinetic energy of the particle, dx is the length of each unit path traveled by the particle, and dE / dx is the average loss dE of the instantaneous kinetic energy E of the particle for each unit path length dx traveled by the particle.

[0061] The γ count reflects the total intensity of γ rays in the mixed radiation field. Each incident γ ray has a fixed probability of generating a triggerable pulse in the front scintillator 2, and this probability is the calibration coefficient . Therefore, the calibration coefficient is subtracted from the gross β count on the front side and the γ count The true β count can be obtained by multiplying the product of the two. This correction principle does not depend on the timing relationship of a single pulse; it only requires statistical accumulation of the count, making it simple and reliable to implement.

[0062] Linear correction calculations involve only multiplication and subtraction, making them suitable for low-power microcontrollers or FPGAs, requiring no floating-point operations or complex functions. If the true beta count... If the value is less than zero, the actual β count is forced to 0 to account for statistical fluctuations under a strong γ field. After the above correction process, the actual β particle count for that time interval is obtained.

[0063] Optionally, before step S303, during factory calibration or field calibration, the detector is irradiated with a gamma radiation source free of alpha and beta contamination, for example, cesium-137 ( 137 Cs) Radioactive source. Under a pure gamma radiation field, all counts in the frontal beta channel originate from gamma interference, and the counts in the rearal gamma channel represent the total gamma count. The detector is then put into calibration mode, and the count rate of the frontal beta channel is measured separately. and the count rate of the back γ channel Then calculate the calibration coefficient according to the following formula. : ; Among them, the calibration coefficient This reflects the average count proportion generated by each incident gamma ray in the frontal β channel. The calculated calibration coefficients... The data is stored in the detector's non-volatile memory and can be directly read and used during normal measurements. If the front scintillator 2 is replaced, for example, by replacing the zinc sulfide silver plastic composite scintillator with a plastic scintillator, the corresponding calibration coefficients need to be recalibrated. .

[0064] S305. Calculate the total count of the front SiPM array 4 in the current cycle and determine whether the total count is greater than the preset threshold. If so, determine the cell coordinates where the count rate peak is located according to the count rate distribution, use the cell coordinates as the projection position of the contamination source on the detector incident surface, and output the projection position and the actual β count. If not, maintain the valid projection position of the previous output, or output a prompt message indicating insufficient count.

[0065] Specifically, based on the count rate distribution, the coordinates of the cell containing the count rate peak are determined, including: Step B1: In the count rate distribution, the first detection unit where the count rate peak is located is taken as the target detection unit.

[0066] Step B2: Obtain the physical coordinates of the target detection unit in the front SiPM array 4, and use the physical coordinates as the unit coordinates.

[0067] Specifically, since both the front SiPM array 4 and the back SiPM array 5 are array-based, such as 16×16 arrays, each detection unit outputs counts independently. The count rate of each detection unit in both SiPM arrays is read in real time to obtain the count rate distribution, forming a two-dimensional count rate distribution map. Because the front scintillator 2 has a pixelated structure, each scintillator pixel is independently coupled to its corresponding front SiPM first detection unit. When an α-contamination source or a β-contamination source is located below the detector probe, only a few scintillator pixels directly above the contamination source can receive the radiation and generate scintillating light, resulting in a significantly higher count rate for the corresponding first detection unit compared to other units. The system accumulates the counts of each first detection unit at a fixed period (e.g., 1 second) to form a count rate distribution. By finding local peaks (maximum values ​​or multiple peaks exceeding a preset threshold) in this distribution, the projection position of the contamination source on the detector's incident surface can be determined. If multiple separate contamination sources exist, the count rate distribution will exhibit multiple local peaks. The system can identify and output the unit coordinates corresponding to all peaks, or generate a two-dimensional count rate heatmap for user judgment. To ensure the statistical reliability of positioning, the position output is only updated when the total count within a period exceeds a preset threshold (e.g., 100); if the count is insufficient, the previous valid position is maintained or an insufficient count is indicated. Positioning accuracy depends on the size of the scintillator pixels, typically ranging from 1mm to 3mm. Since the pixel size is consistent with the SiPM cell spacing (1mm to 3mm), and the spot diameter of α / β particles in the scintillator is smaller than the pixel size, the positioning accuracy can reach the pixel size level.

[0068] In step S305, the following measurement results are output to the display screen or host computer interface: α count, true β count, γ count, projected location (i.e., the location coordinates of the pollution source, or a two-dimensional thermal map), and optionally, the γ energy spectrum. The α count is only valid in the detector's first operating mode. Additionally, diagnostic information, such as the β count before correction and the correction amount, can be output for calibration purposes.

[0069] Optionally, the present invention also provides a gamma-ray spectrum acquisition function. Specifically, the pulse amplitude output by the back-side SiPM array 5 is proportional to the energy of gamma rays deposited in the back-side scintillator 3. The pulse amplitude is quantized by a peak hold circuit and an analog-to-digital converter, and then processed by energy calibration to obtain the gamma-ray spectrum, which can be used to identify the types of radionuclides.

[0070] Optionally, to improve correction accuracy, the detection method of the present invention may further include a time coincidence function. Specifically, a time coincidence window can be programmably opened, the width of which can be set according to actual needs, for example, on the order of nanoseconds to hundreds of nanoseconds. When a frontal pulse is triggered, the time coincidence window is activated, and it is detected whether a back-side trigger is present within the time coincidence window. If a trigger signal is present within the time coincidence window... Trigb If the positive pulse is indeed from the same gamma-ray response, it is highly likely that the positive pulse originates from the same gamma-ray response, and this positive pulse is marked as a gamma-ray interference pulse. The correction strategy can then be adjusted accordingly, for example, by partially subtracting only unmarked positive beta pulses, or by using it to diagnose the detector's state. It should be noted that this timing coincidence function is not essential for achieving the core correction of this invention. The core correction of this invention does not depend on the timing coincidence window; pure statistical correction can achieve excellent results.

[0071] Figure 4 The schematic diagram illustrates the detection method flow of an integrated αβγ detector with a dual-sided SiPM array. Figure 2 See Figure 4 As shown, initialization is performed first, including clearing all counters and setting time intervals. Then, the main loop begins: the first electrical signal output from the front SiPM array 4 is read in real time, and the amplitude and pulse width of each pulse are evaluated. If the pulse amplitude is greater than a preset amplitude threshold and the pulse width is greater than a preset width threshold, it is determined to be an α pulse, and the α counter is incremented by 1; otherwise, it is determined to be a non-α pulse, and the β-hair counter is incremented by 1. Simultaneously, the count rate distribution of each first detection unit in the front SiPM array 4 is recorded. At the same time, the second electrical signal output from the back SiPM array 5 is read in real time, and each valid pulse is accumulated to the γ counter. When the time interval arrives, the β-hair count, γ count, and α count within the current time interval are read. The calibration coefficients pre-stored in the detector are called, and a linear correction calculation is performed: the product of the calibration coefficients and the γ count is subtracted from the β-hair count to obtain the true β count; if the calculation result is less than zero, the true β count is set to zero; otherwise, the calculation result is maintained. Next, based on the recorded count rate distribution of the front SiPM array 4, the coordinates of the unit where the count rate peak is located are determined, and these coordinates are used as the projection position of the pollution source on the detector's incident surface. Finally, output the α count, actual β count, γ count, and projected location of the pollution source for that time interval. After outputting, clear all accumulated count values ​​for the current time interval, return to the beginning of the main loop, and continue reading the pulse for the next time interval.

[0072] This invention relates to an integrated double-sided SiPM array αβγ detector and detection method. It combines an integrated double-sided SiPM array structure with physical blocking and statistical anti-coincidence correction algorithms to achieve composite detection of α, β, and γ rays, γ interference subtraction, and precise location of contamination sources using a single probe and a single set of readout electronics. Specifically, it involves, for the first time, soldering the front SiPM array 4 and the back SiPM array 5 to the front and back sides of the same PCB, utilizing the PCB thickness (≥1.0mm) as both the primary physical blocking layer for α / β rays and the signal carrier. This integrated double-sided SiPM array structure achieves an ultra-thin (≤10mm), lightweight, and highly integrated detection unit, eliminating the need for optical fibers, independent photoelectric conversion devices, and reflectors, completely eliminating optical crosstalk, and enabling lightweight handheld devices. The signal from the back SiPM array 5 originates solely from γ rays, while the signal from the front SiPM array 4 comes from α, β, and γ interference. No complex pulse shape discrimination is required; only simple amplitude / pulse width discrimination is needed, greatly simplifying the electronics. This invention provides a method for determining the probability of generating triggerable pulses from thin, frontal scintillators 2 with a thickness of no more than 1 mm. The probability is approximately independent of the energy of the gamma rays. This is based on the relatively flat energy deposition distribution of Compton-scattered electrons in thin scintillators. Therefore, the calibration coefficients remain constant over a wide gamma energy range of 100 keV to 3 MeV and a wide temperature range of -20℃ to 50℃. This invention employs a linear correction formula to correct the β-hair count, where the calibration coefficients are constants calibrated only once. This linear correction algorithm is simple to calculate, requires no frequent calibration, and is suitable for low-power handheld devices. This invention utilizes the characteristic that both-sided SiPM arrays are arrays to achieve precise location (millimeter-level accuracy) of α / β surface contamination sources by analyzing the count rate distribution of each detection unit in the array. It can also generate a contamination distribution heatmap, which has significant practical value for nuclear emergency response, surface contamination detection, and hotspot location. By replacing the frontal scintillator 2, the same detector can operate in either αβγ full-measurement mode or βγ-dedicated mode, increasing the instrument's flexibility and eliminating the need for hardware redesign, adapting to different scenarios. The signal amplitude of the back-side SiPM array 5 can be used to reconstruct the γ-energy spectrum, enabling nuclide identification and expanding application capabilities.

[0073] In summary, due to the different physical properties of the interaction between α / β rays and γ rays in the scintillator, this invention employs a differentiated scintillator design: the front scintillator, used for precise localization of α / β contamination sources, adopts a pixelated structure (corresponding one-to-one with SiPM units); while the back scintillator, used for γ counting and approximate localization, adopts a continuous flat plate structure (non-pixelated). This design effectively controls the manufacturing cost and complexity of the device while meeting the respective performance requirements.

[0074] It should be noted that the above description of the detection method embodiment for the integrated αβγ detector with a dual-sided SiPM array is similar to the description of the above embodiment of the integrated αβγ detector with a dual-sided SiPM array, and has similar beneficial effects to the embodiment of the integrated αβγ detector with a dual-sided SiPM array. For technical details not disclosed in the embodiments of the detection method for the integrated αβγ detector with a dual-sided SiPM array of the present invention, please refer to the description of the embodiment of the integrated αβγ detector with a dual-sided SiPM array of the present invention for understanding.

[0075] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A dual-sided SiPM array integrated αβγ detector, characterized in that, include: A circuit board, the thickness of which is sufficient to block alpha particles and beta particles with energies below 0.6 MeV, while allowing gamma rays to penetrate; A front scintillator is disposed on one side of the circuit board and is used to generate a first scintillator light in response to incident rays; the front scintillator is a pixelated scintillator. A back-side scintillator, disposed on the other side of the circuit board, is used to generate a second scintillator light in response to gamma rays penetrating the circuit board; A front-side SiPM array is soldered to one side of the circuit board and optically coupled to the front-side scintillator. The front-side SiPM array includes multiple first detection units; each first detection unit is used to convert the first scintillating light into a first electrical signal and output the first electrical signal. A back-side SiPM array is soldered to the other side of the circuit board and optically coupled to the back-side scintillator. The back-side SiPM array includes multiple second detection units; each second detection unit is used to convert the second scintillator light into a second electrical signal and output the second electrical signal. A processor, disposed on the circuit board and coupled to the front SiPM array and the back SiPM array, is used to receive the first electrical signal output by each first detection unit and the second electrical signal output by each second detection unit; and to statistically analyze the count rate distribution of the first electrical signal output by each first detection unit, and determine the location of the α pollution source and / or β pollution source based on the count rate distribution; The γ count is determined based on the second electrical signal, and the β count is corrected based on the γ count; The correction of the β count based on the γ count includes: Based on the β-hair count and the γ-count, the calibration coefficients pre-stored in the detector are invoked to perform a linear correction calculation on the β-hair count to obtain the true β-count; the calibration coefficients are used to characterize the number of pulses generated on average by each incident γ-ray in the frontal scintillator and included in the β-hair count; The circuit board serves as both the mechanical support and electrical connection carrier for the front-side SiPM array and the back-side SiPM array.

2. The integrated αβγ detector with a dual-sided SiPM array according to claim 1, characterized in that, The circuit board is a printed circuit board with a thickness of ≥1.0mm.

3. The integrated αβγ detector with a dual-sided SiPM array according to claim 1, characterized in that, The front scintillator is a zinc silver sulfide plastic composite scintillator or a plastic scintillator, and the thickness of the front scintillator is 0.3 mm to 1.0 mm; The zinc-silver sulfide plastic composite scintillator is used to detect alpha and beta rays; the plastic scintillator is used to detect gamma rays.

4. The integrated αβγ detector with a dual-sided SiPM array according to claim 1, characterized in that, The back scintillator is a plastic scintillator with a thickness of 5mm to 10mm.

5. The integrated αβγ detector with a dual-sided SiPM array according to claim 1, characterized in that, The front-side SiPM array and / or the back-side SiPM array are 4×4 arrays, 8×8 arrays, or 16×16 arrays, and the cell spacing of the front-side SiPM array and / or the back-side SiPM array is 1mm to 3mm.

6. The integrated αβγ detector with a dual-sided SiPM array according to claim 1, characterized in that, The circuit board also integrates a temperature sensor, which is used to monitor the ambient temperature and perform temperature compensation on the gain of the front SiPM array and / or the back SiPM array based on the ambient temperature. And / or, the circuit board is also provided with an coded resistor, which is used to identify the type of the front scintillator and automatically switch the working mode of the detector according to the type.

7. A detection method based on the dual-sided SiPM array integrated αβγ detector as described in claim 1, characterized in that, include: In calibration mode, the detector is irradiated with a gamma radiation source without alpha or beta contamination. The count rate of the front beta channel and the count rate of the back gamma channel are obtained. The count rate of the front beta channel is divided by the count rate of the back gamma channel to calculate the calibration coefficient, and the calibration coefficient is stored. In measurement mode, for each pulse of the first electrical signal output by the front SiPM array, it is determined whether the amplitude of the current pulse is greater than a preset amplitude threshold and whether the width of the current pulse is greater than a preset width threshold. If yes, the current pulse is determined to be an α pulse and the α count is accumulated; if no, the current pulse is determined to be a non-α pulse, the non-α pulse is accumulated as a β count, and the count rate distribution of each first detection unit in the front-side SiPM array is recorded; the thickness of the front-side scintillator is 0.3mm to 1.0mm, and the front-side scintillator is a plastic scintillator or a zinc sulfide silver plastic composite scintillator; the preset amplitude threshold is... The preset width threshold is , , ; Based on the second electrical signal output from the back-side SiPM array, each pulse in the second electrical signal is accumulated as a γ count; Based on the β hair count and the γ count, the calibration coefficients pre-stored in the detector are called to perform a linear correction calculation on the β hair count to obtain the true β count; The total count of the front-side SiPM array within the current period is counted, and it is determined whether the total count is greater than a preset threshold. If yes, then based on the count rate distribution, determine the cell coordinates where the count rate peak is located, use the cell coordinates as the projection position of the pollution source on the detector incident surface, and output the projection position and the actual β count; if no, then maintain the valid projection position of the previous output, or output a prompt message indicating insufficient count.

8. The detection method of the integrated αβγ detector with a dual-sided SiPM array according to claim 7, characterized in that, The step of using the β hair count and the γ count to call the calibration coefficients pre-stored in the detector to perform a linear correction calculation on the β hair count to obtain the true β count includes: Multiply the γ count by the calibration coefficient to obtain the γ interference estimate; The difference between the β count and the γ interference estimate is determined as the true β count; Determine whether the true β count is less than zero. If it is, set the true β count to zero; otherwise, keep the true β count unchanged.

9. The detection method of the integrated αβγ detector with a dual-sided SiPM array according to claim 7, characterized in that, Determining the cell coordinates of the peak count rate based on the count rate distribution includes: In the count rate distribution, the first detection unit where the count rate peak is located is taken as the target detection unit; The physical coordinates of the target detection unit in the front-facing SiPM array are obtained, and the physical coordinates are used as the unit coordinates.

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