A hybrid neutron gamma detector array and signal processing method

Abstract

The application discloses a mixed neutron gamma detector array and a signal processing method, and relates to the technical field of nuclear physics detection.The eight EJ200 scintillators arranged in the array are used for energy deposition of gamma rays and fast neutrons and for generating photons, and three EJ426 thermal neutron scintillation screens are used for capturing thermal neutrons and generating photons, so that the responses of the gamma rays, the fast neutrons and the thermal neutrons are realized at the same time, and the detection precision is greatly improved.Meanwhile, when the three EJ426 thermal neutron scintillation screens are alternately stacked in front and back, the total reflectivity of the EJ200 scintillators and the semi-opaque property of the EJ426 thermal neutron scintillation screens are utilized to block the propagation of the X-direction photons, so that the photons only propagate in the Y and Z directions, and the four-channel photon collection structure corresponding to each EJ200 scintillator is utilized to collect the photons with high efficiency, so that high-precision detection and high-efficiency photon collection are realized, and support is provided for subsequent strong radiation field monitoring or high-precision positioning.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of nuclear physics detection, in particular to a hybrid neutron gamma detector array and a signal processing method. BACKGROUND

[0002] Nuclear geophysical exploration, referred to as nuclear physics detection, is a geophysical method based on the interaction between particles such as neutrons and photons and medium atomic nuclei, which is used for mineral resource detection and geological problem analysis; it is different from natural radioactivity measurement, and realizes short-range detection through artificial sources, and is mainly applied to the fields of drilling, tunneling and sample analysis; the effective differentiation and accurate detection of neutrons and gamma rays have always been a research difficulty.

[0003] The mainstream detector at the present stage is mainly in the form of a single scintillator or multiple scintillators stacked, but because the detector at the present stage is only simply set or simply stacked, the detection accuracy is low when detecting neutrons and gamma rays, and at the same time, because the detector at the present stage does not limit the propagation of photons, the photon collection efficiency is low.

[0004] Therefore, the detector at the present stage has the problems of low detection accuracy and low photon collection efficiency, which makes it difficult to meet the needs of strong radiation field monitoring or high-precision positioning scenes. SUMMARY

[0005] The embodiment of the present application provides a hybrid neutron gamma detector array and a signal processing method, which can solve the problems in the prior art.

[0006] The embodiment of the present application provides a hybrid neutron gamma detector array, which comprises eight EJ200 scintillators arranged in a three-dimensional array, three EJ426 thermal neutron scintillation screens alternately stacked between the three-dimensional array formed by the eight EJ200 scintillators, and two photomultiplier tubes arranged on each EJ200 scintillator without EJ426 thermal neutron scintillation screen shielding the two end faces.

[0007] The EJ200 scintillator is used for depositing the energy of the gamma rays and fast neutrons emitted by the neutron source, and generating photons according to the deposited energy; after the fast neutrons emitted by the neutron source are moderated into thermal neutrons, the three EJ426 thermal neutron scintillation screens are used for capturing thermal neutrons and generating photons.

[0008] The total reflectivity of the eight EJ200 scintillators and the semi-opaque property of the three EJ426 thermal neutron scintillation screens are used for limiting the propagation path direction of the photons, so that the photons propagate in the direction without EJ426 thermal neutron scintillation screen shielding.

[0009] Each of the EJ200 scintillators corresponds to four photomultiplier tubes in four directions without the shielding of EJ426 thermal neutron scintillation screen, for forming a four-channel acquisition structure to acquire photons.

[0010] Preferably, a mechanical support structure is further included, which is a stainless steel support arranged at the bottom of the detector array for fixing the detector array.

[0011] Preferably, a dark box is further included, which is a paper dark box, the detector array is placed inside the paper dark box, and the inner wall of the paper dark box is coated with a matte black paint for reducing environmental light interference.

[0012] Preferably, a moderator is further included, which is a high-density polyethylene (HDPE) plate arranged between the neutron source and the detector array for slowing down fast neutrons emitted by the neutron source into thermal neutrons.

[0013] Preferably, each EJ200 scintillator is connected to the photomultiplier tubes arranged at both ends thereof through a light guide material.

[0014] The embodiment of the present application further provides a signal processing method of the hybrid neutron gamma detector array, including the following steps:

[0015] The charge data output by the photomultiplier tubes are acquired, and a pulse shape discrimination (PSD) method is used to set a long integration window to acquire full waveform charges of the charge data and a short integration window to extract front edge features in the charge data.

[0016] According to the charge amount of the full waveform charges and the charge amount of the front edge features, a PSD value is obtained, and a value range of the PSD value is divided into a gamma signal area and a neutron signal area to distinguish gamma signals and neutron signals.

[0017] For the four-channel electrical signals corresponding to each EJ200 scintillator, time differences between the acquisition of electrical signals by two channels are calculated, and gamma events, neutron events and gamma neutron mixed events are distinguished according to the time difference values to perform positioning of the neutron source.

[0018] Preferably, the distinguishing of the gamma signals and the neutron signals includes:

[0019] The PSD value is obtained in the following manner:

[0020] PSD = 1 - Q short / Q long ;

[0021] Wherein: Q short represents the charge amount in the short integration window of 50 ns; and Q long represents the charge amount in the long integration window of 1000 ns.

[0022] If PSD is in [-0.5, 0], the signal is determined as a gamma signal, if PSD is in [0.5, 1.0], the signal is determined as a neutron signal, and if PSD is in [0, 0.5], the signal is determined as a mixed signal or noise.

[0023] Preferably, the positioning of the neutron source comprises:

[0024] For each four-channel electrical signal corresponding to an EJ200 scintillator, the time difference between the acquisition of the electrical signals of two channels is calculated;

[0025] The time difference is divided into intervals and Gaussian fitted:

[0026] When the main peak of the time difference is located in [-1 ns, 1 ns] and the half-height width is 2 ns, and there is an incoherent fluctuation in [-20 ns, 20 ns], the signal is determined as a neutron event;

[0027] When the time difference is concentrated in [-10 ns, 10 ns] and presents a single-peak Gaussian distribution, and the peak position is 0 ns and the half-height width is 5 ns, the signal is determined as a gamma event;

[0028] When the time difference is concentrated in [-100 ns, 100 ns] and the time difference is 35 ns, the signal is determined as a mixed event of neutron and gamma, the event type is verified by the half-height width of Gaussian fitting, and the neutron event and the gamma event are determined;

[0029] The propagation path of the photon is deduced from the time difference corresponding to the neutron event, and the position of the neutron source is obtained by combining the moderation time of the neutron through the moderator.

[0030] Compared with the prior art, the mixed-type neutron-gamma detector array and the signal processing method have the following beneficial effects:

[0031] The eight EJ200 scintillators are arranged in a three-dimensional array, three EJ426 thermal neutron scintillation screens are alternately stacked between the three-dimensional array, and photomultiplier tubes are arranged on the two end surfaces of each EJ200 scintillator; during detection, the eight EJ200 scintillators arranged in an array are used for energy deposition of gamma rays and fast neutrons and generate photons, and the three stacked EJ426 thermal neutron scintillation screens are used for capturing thermal neutrons and generating photons, so as to simultaneously realize the response of gamma rays, fast neutrons and thermal neutrons, and greatly improve the detection accuracy; and at the same time, when the three EJ426 thermal neutron scintillation screens are alternately stacked in front and back, the full reflectivity of the EJ200 scintillator and the semi-opaque property of the EJ426 thermal neutron scintillation screen are utilized to block the propagation of X-direction photons, so that the photons only propagate in the Y and Z directions, and the four-channel photon acquisition structure corresponding to each EJ200 scintillator is utilized to collect the photons with high efficiency, thereby realizing high-precision detection and high-efficiency photon collection, and providing support for subsequent strong radiation field monitoring or high-precision positioning.

[0032] And, the present application adopts pulse shape discrimination (PSD) method to set long integration window 1000 ns to collect full waveform charge of electric charge data, short integration window 50 ns to extract front feature in electric charge data, according to charge amount of full waveform charge and charge amount of front feature, obtain PSD value, divide value range of PSD value into gamma signal area and neutron signal area to distinguish gamma signal and neutron signal, solve signal drift problem of traditional ratio method in mixed array, and improve classification precision of neutron signal and gamma signal.

[0033] Moreover, the present application calculates time difference between two electric signals corresponding to four photomultiplier tubes of a single scintillator, focuses on two groups of electric signals corresponding to neutron events, that is, focuses on two groups of electric signals with maximum time difference to deduce photon propagation path, and combines neutron slowing time to obtain position of neutron source, so that positioning precision of the neutron source can be improved. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 A schematic diagram of an overall layout structure of a mixed neutron gamma detector array is provided for the embodiment of the present application.

[0035] Figure 2 A physical display schematic diagram of a mixed neutron gamma detector array is provided for the embodiment of the present application.

[0036] Figure 3 A PSD value classification result schematic diagram of four PMT responses around a scintillator 6 when a neutron source is at position 14 is provided for the embodiment of the present application.

[0037] Figure 4 A two-dimensional PSD histogram when a neutron source is at position 14 and four PMT responses around a scintillator 6 are provided for the embodiment of the present application.

[0038] Figure 5 A time difference distribution schematic diagram of two PMTs of a scintillator 6 corresponding to a label 8 and a label 7 is provided for the embodiment of the present application.

[0039] Figure 6 A time difference distribution schematic diagram of two PMTs of a scintillator 6 corresponding to a label 2 and a label 14 is provided for the embodiment of the present application. DETAILED DESCRIPTION

[0040] In order to make the above objectives, characteristics and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application are described in detail below with reference to the drawings. In the following description, a large number of specific details are set forth in order to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the concept of the present application, so the present application is not limited to the specific embodiments disclosed below.

[0041] At present, in the field of neutron gamma detectors, the conventional detector is a single scintillator (such as EJ200 or EJ426), but it is difficult to simultaneously respond to gamma rays and neutrons; among them, EJ200 is sensitive to gamma but has low neutron detection efficiency, EJ426 is dedicated to thermal neutrons but cannot detect gamma rays, resulting in high signal misjudgment rate in mixed radiation field; at the same time, the structure design of the detector lacks optimization of the photon propagation path, resulting in low photon collection efficiency and complex time difference distribution; and the signal processing algorithm does not fully consider the interaction of the mixed scintillator, resulting in unsatisfactory PSD (pulse shape discrimination) index and FOM (figure of merit) value, affecting subsequent analysis.

[0042] And in the processing of the photon signal of the detector, the existing pulse shape discrimination (PSD) technology adopts a fixed integral window ratio method, which causes PSD value drift in the mixed array due to signal attenuation, and the quality factor FOM is generally lower than 2.5, which is difficult to meet the 3σ classification accuracy requirement; at the same time, the time difference analysis does not distinguish the event type, and the neutron source positioning error often exceeds 10 cm; therefore, the present application provides a new type of mixed neutron gamma detector array and a signal processing method thereof.

[0043] As shown in Figure 1 , the embodiment of the present application provides a mixed neutron gamma detector array, which comprises 16 photomultiplier tubes PMT, which are respectively labeled as 1, 2, 3, 4, 5, 6 (blocked), 7, 8, 9 (blocked), 10, 11, 12, 13, 14, 15 and 16; 3 EJ426 thermal neutron scintillation screens, which are respectively labeled as 17, 18 and 19; 8 EJ200 scintillators, which are respectively labeled as 20 (blocked), 21, 22, 23, and the EJ200 scintillators arranged below 20 (blocked), 21, 22, 23; a mechanical support system comprising a support structure and a dark box shield; a neutron moderation and positioning system comprising a neutron moderator and a positioning coordinate system; wherein, in Figure 1 , because the labels 6, 9 and 20 are blocked, the form of adding (blocked) after the label is used to indicate the device represented by the label.

[0044] Among them, eight EJ200 scintillators are arranged in a 2x2x2 three-dimensional array, used for energy deposition and photon generation of gamma rays and fast neutrons, and the size is adapted to the array layout; three EJ426 thermal neutron scintillation screens, specifically 12 cm x 12 cm x 1 mm thin plates, are stacked in the gaps of the three-dimensional array formed by the eight EJ200 scintillators, between the front and rear layers, for slow neutron capture reactions and photon generation; at the same time, the total reflection characteristics of the EJ200 scintillator and the semi-opaque property of the EJ426 thermal neutron scintillation screen are used to block the propagation of X-direction photons, leaving only the Y and Z direction straight propagation paths.

[0045] Among them, 16 photomultiplier tubes PMT correspond to the two end faces of each EJ200 scintillator, forming four-channel signal acquisition (such as scintillator 6 corresponding to PMT2, PMT14, PMT7, PMT8), and the light coupling efficiency is enhanced through light guide material; the support structure uses a stainless steel bracket to fix the position of the assembly, ensuring that the three-dimensional coordinate accuracy error is ≤0.5 mm; the dark box shielding uses a paper dark box (inner wall matte black paint) to simulate the final design, and the average distance from the neutron source to the center of the detector is controlled to be 40 cm, reducing environmental light interference.

[0046] Among them, the neutron moderator: a 10 cm thick HDPE material is placed between the neutron source and the detector to slow down fast neutrons to thermal neutrons, improving the EJ426 reaction efficiency; the positioning coordinate system: taking the center of the detector as the origin, combined with time difference backstepping to realize positioning through multiple position neutron source placement (such as position 14: 30 cm, 2.5 cm, -15 cm).

[0047] In signal processing, the designed PSD value classification algorithm: (1) Double integration window parameters: long integration window 1000 ns collects full waveform charge, short integration window 50 ns extracts front feature, and the improved calculation formula is: PSD = 1 - Q short / Q long ; (2) Signal classification interval: gamma signals are concentrated in PSD ∈ [-0.5, 0] (left region L), and neutron signals are concentrated in PSD ∈ [0.5, 1.0] (right region R), and the classification accuracy is ensured through the 3σ standard.

[0048] The designed time difference distribution analysis method: (1) Six groups of time difference calculation: for the four PMTs corresponding to a single scintillator, the time difference between each other is calculated, and the two groups farthest away (such as PMT2 and PMT14) are mainly analyzed; (2) Three-stage interval screening strategy: A. Gamma event: the time difference is concentrated in [-10ns, 10ns], showing a single peak Gaussian distribution (peak position ≈0ns, half width ≈5ns); B. Neutron event: the main peak is located in [-1ns, 1ns] (half width ≈2ns), accompanied by [-20ns, 20ns] incoherent fluctuations; C. Mixed event: the combination of neutron and gamma signals produces a time difference of about 35ns, distributed in [-100ns, 100ns].

[0049] FOM value optimization strategy: (1) Two-dimensional PSD histogram analysis: through threshold setting optimization (such as left upper / right lower arc line truncation control), adjust the integral parameters to maintain the FOM value at about 3.00, and ensure that the histogram structure is not distorted; (2) Collector parameter adaptation: using 16 MHz clock and 4096 channel resolution, amplifying and processing short integration signals, compatible with negative PSD calculation and does not affect FOM evaluation.

[0050] The technical advantages of the application in structural design: (1) Multi-radiation field compatible detection: EJ200 and EJ426 hybrid array simultaneously realize the response of gamma ray, fast neutron and thermal neutron, expanding the detection range; (2) Mechanical precision and shielding optimization: the combination of stainless steel bracket and paper dark box controls the assembly error within millimeter level, and balances the shielding effect and positioning feasibility through 40 cm source distance design; (3) Simplification of photon propagation path: using material optical properties to limit photon propagation in Y and Z directions only, reducing cross talk and lowering signal analysis complexity.

[0051] The performance improvement of the application in signal processing: (1) PSD classification accuracy breakthrough: realizing more than 3sigma signal differentiation, stable two-dimensional PSD histogram structure, suitable for real-time analysis in complex radiation field; (2) Neutron source positioning efficiency improvement: through three-stage interval fitting of time difference, the positioning error under 40 cm distance is controlled within 5 cm, meeting the needs of nuclear safety monitoring; (3) Efficient use of hardware resources: improved PSD algorithm compatible with collector parameter amplification design, fully utilizing 4096 channel resolution, improving signal processing efficiency.

[0052] The application can be directly applied to real-time monitoring and source positioning of neutron gamma mixed field in nuclear material transportation, radiation type identification and dose accurate evaluation in industrial nondestructive testing, and neutron background suppression and gamma dose calibration in medical radiotherapy equipment, with significant engineering practicability and market application prospect.

[0053] In specific experiments, as shown in Figure 2 The detector assembly is assembled:

[0054] A, eight EJ200 scintillators are arranged in a three-dimensional array, and EJ426 thermal neutron scintillation screens are inserted between the layers to ensure that the EJ200 and EJ426 are closely attached and reduce photon leakage.

[0055] B, 16 PMTs are respectively installed on the end face of the EJ200 scintillator, and light guide material is used to enhance the photon coupling efficiency, and each scintillator is symmetrically detected by two PMTs (such as scintillator 6 corresponding to PMT2, PMT14, PMT7, and PMT8).

[0056] C, the stainless steel support is welded in a 2×2×2 structure to ensure that the position accuracy error of each component is not more than 0.5 mm, and to avoid affecting the photon propagation path due to mechanical deviation.

[0057] Dark box and neutron source arrangement:

[0058] A, the size of the paper dark box is 30 cm×30 cm×30 cm, and the inner wall is sprayed with matte black paint to reduce light reflection interference.

[0059] B, taking the center of the detector as the origin (0, 0, 0), the neutron source is placed at position 14 (30 cm, 2.5 cm, -15 cm), and a 10 cm thick HDPE moderator is placed between the source and the detector to ensure that the average distance from the neutron source to the center of the detector is about 40 cm.

[0060] Data acquisition parameters:

[0061] (1) The collector uses a 16 MHz clock, 30-bit time stamp, and the time resolution is 1 / 16 MHz = 62.5 ns, and the time difference accuracy can reach nanosecond level.

[0062] (2) In order to fully utilize the 4096-channel collector, the short integration window (50 ns) signal is amplified and processed, allowing the PSD value to appear negative (which does not affect the FOM calculation).

[0063] PSD value calculation and classification:

[0064] (1) PSD calculation formula: PSD = 1–Q short / Q long , where Q short is the short integration window (50 ns) charge, and Q long is the long integration window (1000 ns) charge.

[0065] (2) According to the PSD value classification: when PSD ∈ [-0.5, 0], it is determined as a gamma signal, when PSD ∈ [0.5, 1.0], it is determined as a neutron signal, and the intermediate interval ([0, 0.5]) is considered as a mixed signal or noise.Figure 3 and Figure 4 Response map of four PMTs around the scintillator for neutron source at position 14, where Figure 3 PSD value classification result, distribution interval of gamma signal (L region) and neutron signal (R region), where Figure 4 Two-dimensional PSD histogram, the arc line truncation at the top left and bottom right is related to the threshold setting of the collector.

[0066] In Figure 3 , Figure 3 The graph in the top left corner represents the PSD value classification result of PMT6 (blocked), Figure 3 The graph in the top right corner represents the PSD value classification result of PMT14, Figure 3 The graph in the bottom left corner represents the PSD value classification result of PMT2, Figure 3 The graph in the bottom right corner represents the PSD value classification result of PMT12.

[0067] Time difference distribution analysis:

[0068] (1) Take scintillator 6 as an example, calculate the time difference between the four PMTs, and focus on analyzing the two groups with the largest time difference (such as PMT2 and PMT14, PMT7 and PMT8), as shown in Figure 5 and Figure 6 .

[0069] Among them, Figure 5 shows the time difference distribution of PMT7 and PMT8, Figure 6 shows the time difference distribution of PMT2 and PMT14.

[0070] (2) Intervals are divided and Gaussian fitting is performed on the time difference data:

[0071] A, in the interval [-10ns, 10ns], the gamma event corresponds to a single-peak Gaussian distribution (peak position about 0ns, half-height width about 5ns), as shown in Figure 5 .

[0072] B, neutron events exist in a smaller Gaussian peak in the interval [-1ns, 1ns] (half-height width about 2ns), and appear in [-20ns, 20ns] with discontinuous fluctuations, as shown in Figure 6 .

[0073] PSD index and FOM value:

[0074] (1) The PSD classification accuracy of the mixed detector array reaches more than 3σ, and the FOM value is 3.00, which is 55% lower than the single EJ200 + EJ426 combination (FOM = 6.61), but the two-dimensional PSD histogram does not appear distortion.

[0075] (2) Analysis of the reasons for the decrease: the total reflection of photons between EJ200 and the semi-opaque characteristics of EJ426 lead to a decrease in photon collection efficiency; the mixed effect of multiple scintillators increases the signal decay path.

[0076] The time difference is associated with the type of signal:

[0077] (1) In the gamma event, the time difference is concentrated in [-10ns, 10ns], which is consistent with the time expectation of straight-line propagation of photons, and the number of cases accounts for 78%.

[0078] (2) In the neutron event, in addition to the main peak, the combination of signals detected by PMT8 and PMT2 will produce a time difference of about 35 ns, which is speculated to be due to: PMT8 / PMT2 triggers neutron signal collection first, but due to the performance of PMT or the limitation of photon propagation, no effective photons are generated, and then PMT7 / PMT14 is triggered by a gamma event.

[0079] The present application can control the positioning error of the neutron source within 5 cm (at an average distance of 40 cm) by time difference back-propagation of photon propagation path and combination of neutron slowing time calculation, meet the positioning needs of conventional radiation monitoring scenes, and prove the feasibility of neutron source positioning.

[0080] The present application realizes high-precision detection and differentiation of neutrons and gamma rays through mixed detector structure design and signal processing algorithm optimization, and experimental verification shows that the PSD classification accuracy is greater than 3σ, and the time difference analysis can assist in neutron source positioning, which has significant technical innovation and practical value.

[0081] The present application adopts a three-dimensional mixed array structure composed of EJ200 scintillator and EJ426 thermal neutron scintillation screen, configures 16 photomultiplier tubes (PMT) to realize efficient collection of photon signals, and optimizes mechanical stability and light shielding effect through stainless steel support and paper dark box design; The signal processing method is based on pulse shape discrimination (PSD) technology and time difference analysis algorithm, which accurately divides gamma signals (PSD∈[-0.5, 0]) and neutron signals (PSD∈[0.5, 1.0]), and the figure of merit (FOM) can reach about 3.00; The present application effectively solves the problems of insufficient signal recognition accuracy and difficulty in neutron source positioning of traditional detectors in complex radiation fields, and can be widely used in nuclear radiation safety monitoring, medical image diagnosis, industrial non-destructive testing and other fields, and has significant technical innovation and engineering application value.

[0082] The above embodiments only express several implementation manners of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the scope of the patent. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, several modifications and improvements can be made, which are within the scope of protection of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A hybrid neutron gamma detector array, characterized in that, It comprises: Eight EJ200 scintillators arranged in a 2x2x2 three-dimensional array, three EJ426 thermal neutron scintillation screens alternately stacked between the three-dimensional array formed by the eight EJ200 scintillators, and photomultiplier tubes arranged on the two end faces of each EJ200 scintillator without being blocked by the EJ426 thermal neutron scintillation screen; The EJ200 scintillator is used to deposit the energy of the gamma rays and fast neutrons emitted by the neutron source, and generate photons according to the deposited energy; after the fast neutrons emitted by the neutron source are moderated into thermal neutrons, the three EJ426 thermal neutron scintillation screens are used to capture thermal neutrons and generate photons; The total reflectivity of the eight EJ200 scintillators and the semi-opaque property of the three EJ426 thermal neutron scintillation screens are used to limit the direction of the photon propagation path, so that the photons propagate in the direction not blocked by the EJ426 thermal neutron scintillation screen; Each EJ200 scintillator corresponds to four photomultiplier tubes in four directions not blocked by the EJ426 thermal neutron scintillation screen, forming a four-channel acquisition structure to collect photons.

2. The hybrid neutron gamma-ray detector array of claim 1, wherein, It also comprises a mechanical support structure, which is a stainless steel support arranged at the bottom of the detector array for fixing the detector array.

3. The hybrid neutron gamma-ray detector array of claim 1, wherein, It also comprises a dark box, which is a paper dark box, and the detector array is placed inside the paper dark box, and the inner wall of the paper dark box is coated with matte black paint to reduce environmental light interference.

4. The hybrid neutron gamma-ray detector array of claim 1, wherein, It also comprises a moderator, which is a high-density polyethylene (HDPE) plate arranged between the neutron source and the detector array to slow down the fast neutrons emitted by the neutron source into thermal neutrons.

5. The hybrid neutron gamma-ray detector array of claim 1, wherein, The photomultiplier tubes arranged on the two end faces of each EJ200 scintillator are connected through a light guide material.

6. The method of claim 1-5, wherein, It comprises the following steps: Collecting the charge data output by the photomultiplier tubes, setting a long integration window to collect the full-waveform charge of the charge data using the pulse shape discrimination (PSD) method, and setting a short integration window to extract the leading edge characteristics of the charge data; According to the charge amount of the full-waveform charge and the charge amount of the leading edge characteristics, the PSD value is obtained; the value range of the PSD value is divided into a gamma signal region and a neutron signal region to distinguish gamma signals and neutron signals; For the four-channel electrical signals corresponding to each EJ200 scintillator, the time difference between the two-channel collected electrical signals is calculated, and the gamma events, neutron events and gamma-neutron mixed events are distinguished according to the time difference value to locate the neutron source.

7. A signal processing method according to claim 6, characterized in that, The distinction between gamma signals and neutron signals comprises: The PSD value is obtained in the following way: PSD = 1 - Q short / Q long ; where: Q short represents short integration window 50 ns charge quantity; Q long represents long integration window 1000 ns charge quantity; If PSD∈[−0.5,0], it is determined as a gamma signal, if PSD∈[0.5,1.0], it is determined as a neutron signal, and if PSD∈[0,0.5], it is determined as a mixed signal or noise.

8. The signal processing method of claim 6, wherein, The location of the neutron source comprises: For the four-channel electrical signals corresponding to each EJ200 scintillator, the time difference between the two-channel collected electrical signals is calculated; The time difference is divided into intervals and Gaussian fitted: The main peak of the time difference is located in [−1ns,1ns] with a half-height width of 2ns, accompanied by [−20ns,20ns] incoherent fluctuations, and it is determined as a neutron event; If the time difference is concentrated in [−10 ns, 10 ns] and is a single-peak Gaussian distribution with a peak position of 0 ns and a half-height width of 5 ns, the event is determined to be a gamma event; If the time difference is concentrated in [−100 ns, 100 ns] and the time difference is 35 ns, the event is determined to be a mixed event of neutrons and gammas, the event type is verified by Gaussian fitting half-height width, and the neutron event and the gamma event are determined; The photon propagation path is deduced through the time difference corresponding to the neutron event, and the position of the neutron source is obtained by combining the moderation time of the neutron through the moderator.

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