A neutron detector and a neutron detection method

Abstract

The application relates to the technical field of neutron detection, and provides a neutron detector and a neutron detection method. The neutron detector comprises a plurality of moderation units and a thermal neutron sensitive layer. The neutrons of a to-be-detected substance can be moderated by the moderation units to generate thermal neutrons. The thermal neutron sensitive layer is arranged on the outer side of the moderation units. The thermal neutrons are captured by the thermal neutron sensitive layer to generate cascade gamma rays. The gamma rays in the gamma radiation field cause the response of a first number of the moderation units. The gamma rays in the gamma radiation field and the cascade gamma rays jointly cause the response of a second number of the moderation units. The neutron detector and the neutron detection method can improve the neutron gamma discrimination ratio.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of neutron detection, and in particular to a neutron detector and a neutron detection method. BACKGROUND

[0002] Neutron gamma discrimination is a technology for fast and accurate neutron detection in a gamma radiation field, which can be used for detection of radioactive substances and special nuclear fuels. The neutron gamma discrimination technology can detect the shielded transportation of special nuclear materials in a gamma radiation field, avoiding the interference of the gamma radiation field on the neutron detector. Therefore, it is an urgent problem to improve the neutron gamma discrimination ratio of the neutron detector. SUMMARY

[0003] Therefore, the embodiments of the present application aim to provide a neutron detector and a detection method, which can improve the neutron gamma discrimination ratio.

[0004] To achieve the above-mentioned purpose, the technical scheme of the embodiments of the present application is as follows:

[0005] The embodiments of the present application disclose a neutron detector, which comprises:

[0006] A plurality of moderation units, the to-be-detected neutrons of a to-be-detected substance can be moderated by the moderation units to generate thermal neutrons;

[0007] A thermal neutron sensitive layer is arranged outside the moderation units, the thermal neutrons are captured by the thermal neutron sensitive layer to generate cascade gamma rays, the gamma rays in the gamma radiation field induce a first number of the moderation units to respond, and the gamma rays in the gamma radiation field and the cascade gamma rays jointly induce a second number of the moderation units to respond.

[0008] In an embodiment, the neutron detector comprises a plurality of photodetectors, and each of the moderation units is coupled with at least one photodetector.

[0009] In an embodiment, the neutron detector comprises a reflective layer, and the outer circumferential surface of each of the moderation units is provided with the reflective layer.

[0010] In an embodiment, a plurality of the moderation units are arranged along the width direction of the neutron detector to form a moderation layer, and a plurality of the moderation layers are stacked along the thickness direction of the neutron detector.

[0011] In an embodiment, the outer circumferential surface of each of the moderation units is surrounded by the thermal neutron sensitive layer.

[0012] In an embodiment, the neutron detector comprises a first protective layer, and the outer circumferential surface of the thermal neutron sensitive layer is surrounded by the first protective layer.

[0013] In one embodiment, a thermal neutron-sensitive layer is laid between two of the multiple moderating layers, or...

[0014] Each pair of adjacent moderating layers is covered with a thermal neutron-sensitive layer.

[0015] In one embodiment, the neutron detector includes a second protective layer, and the outer peripheral surface of each of the slowing units is provided with the second protective layer.

[0016] In one embodiment, the neutron detector includes lead plates, with one lead plate disposed between each two adjacent moderating layers.

[0017] In one embodiment, the number of moderating layers is between 3 and 5.

[0018] In one embodiment, the thickness of the thermal neutron-sensitive layer is between 20 μm and 30 μm.

[0019] Another aspect of this application discloses a neutron detection method for use with the neutron detector in any of the above embodiments, the detection method comprising:

[0020] The first number of the slowing units in response to gamma rays in the gamma radiation field is set as a threshold.

[0021] If the total number of responses from the moderating units is greater than the threshold, it is determined that the analyte contains the analyte neutron.

[0022] In one embodiment, the threshold is between 2 and 4.

[0023] This application discloses a neutron detector and a neutron detection method. The method first uses a moderation unit to slow down neutrons emitted by the analyte, generating thermal neutrons. Then, a thermal neutron-sensitive layer captures these thermal neutrons to generate cascaded gamma rays. The gamma rays in the gamma radiation field can deposit energy within multiple moderation units, causing a first number of moderation units to respond. The combined energy deposition of gamma rays in the gamma radiation field and the cascaded gamma rays in multiple moderation units can trigger a second number of moderation units to respond. Thus, when detecting the analyte, the number of responses from the moderation units can be used to distinguish between neutrons and gamma rays. This simplifies the detection process, shortens the detection time, and reduces the occurrence of false positives, improving the detection accuracy of the neutrons. Furthermore, it reduces the interference of gamma rays in the gamma radiation field on the neutron detector, improving the neutron-gamma discrimination ratio. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of a neutron detector provided in an embodiment of this application;

[0025] Figure 2 for Figure 1 Enlarged view of point A in the middle;

[0026] Figure 3 for Figure 2 Enlarged view of point B in the middle;

[0027] Figure 4 This is a schematic diagram of another neutron detector provided in an embodiment of this application, wherein a thermal neutron-sensitive layer is provided around the outer periphery of each moderation unit;

[0028] Figure 5 This is a graph showing the relationship between the number of moderation layers and the detection efficiency of the neutron to be measured.

[0029] Figure 6 This is a graph showing the relationship between the thickness of the thermal neutron-sensitive layer and the detection efficiency of the neutrons to be measured.

[0030] Figure 7 A flowchart illustrating a neutron detection method according to another embodiment of this application;

[0031] Figure 8 This is a graph showing the relationship between the number of responses of a photodetector and the number of signals.

[0032] Explanation of reference numerals in the attached figures

[0033] Neutron detector 100; moderation unit 1; thermal neutron sensitive layer 2; reflective layer 3; first protective layer 4; second protective layer 5. Detailed Implementation

[0034] It should be noted that, unless otherwise specified, the embodiments and technical features in the embodiments of this application can be combined with each other, and the detailed descriptions in the specific implementation should be understood as explanations of the purpose of this application and should not be regarded as undue limitations on this application.

[0035] The present application will now be described in further detail with reference to the accompanying drawings and specific embodiments. The terms "first," "second," etc., used in the embodiments of this application are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly including at least one feature. In the description of the embodiments of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0036] In related technologies, detecting whether a analyte contains the target neutron requires analyzing and detecting its deposited energy, including full-energy peaks, which involves numerous steps and a long detection time. Furthermore, because gamma rays in a gamma radiation field can directly deposit energy within a moderation unit to trigger a response, misjudgments can occur, leading to inaccurate detection.

[0037] In view of this, one embodiment of this application provides a neutron detector, please refer to... Figure 1 As shown in Figure 4, the neutron detector 100 includes multiple moderation units 1 and a thermal neutron-sensitive layer 2. Detectable neutrons from the analyte can be slowed down by the moderation units 1 to produce thermal neutrons. The thermal neutron-sensitive layer 2 is disposed outside the moderation units 1. Thermal neutrons are captured by the thermal neutron-sensitive layer 2 to generate cascaded gamma rays. The gamma rays in the gamma radiation field trigger a response in a first number of moderation units 1. The gamma rays in the gamma radiation field and the cascaded gamma rays together trigger a response in a second number of moderation units 1.

[0038] In this embodiment, the neutrons emitted by the analyte are first slowed down by the moderation unit 1 to generate thermal neutrons. Then, the thermal neutron-sensitive layer 2 captures the thermal neutrons to generate cascaded gamma rays. The gamma rays in the gamma radiation field can deposit energy in multiple moderation units 1, causing a first number of moderation units 1 to respond. The gamma rays in the gamma radiation field and the cascaded gamma rays deposit energy in multiple moderation units 1 together, causing a second number of moderation units 1 to respond. In this way, when detecting the analyte, the number of responses from the moderation units 1 can be used to distinguish neutrons and gamma rays. On the one hand, this simplifies the detection steps, shortens the detection time, and reduces the occurrence of false positives, thereby improving the detection accuracy of the analyte. On the other hand, it reduces the interference of gamma rays in the gamma radiation field on the neutron detector 100, thereby improving the neutron-gamma discrimination ratio.

[0039] In one embodiment, the neutron detector 100 includes multiple photodetectors. Exemplarily, neutrons from the analyte can be slowed down by a moderation unit 1 to produce thermal neutrons. A thermal neutron-sensitive layer 2 is disposed outside the moderation unit 1. Thermal neutrons are captured by the thermal neutron-sensitive layer 2 to generate cascaded gamma rays. The gamma radiation field deposits energy in the moderation unit 1, producing a first scintillation. The gamma rays from the gamma radiation field and the cascaded gamma rays jointly deposit energy in the moderation unit 1, producing a second scintillation. Each moderation unit 1 is coupled to at least one photodetector, which is capable of responding to either the first or second scintillation.

[0040] In this embodiment, the neutrons emitted by the analyte are first slowed down by the moderation unit 1 to generate thermal neutrons. Then, the thermal neutrons are captured by the thermal neutron-sensitive layer 2 to generate cascaded gamma rays. The gamma rays in the gamma radiation field can deposit energy within the moderation unit 1 and emit a first scintillation. The gamma rays in the gamma radiation field and the cascaded gamma rays together deposit energy in the moderation unit 1 and emit a second scintillation. Finally, a photodetector responds to either the first or second scintillation. In other words, the gamma rays in the gamma radiation field are detected by the neutron detector 100 along with the neutrons emitted by the analyte. The gamma rays in the gamma radiation field can directly penetrate the neutrons emitted by the analyte. The neutron-sensitive layer directly deposits energy in the moderation unit 1 to emit the first scintillation light. The neutron to be measured will also penetrate the neutron-sensitive layer first, and then be moderated by the moderation unit 1 to produce thermal neutrons and be scattered away from the moderation layer. The scattered thermal neutrons are captured by the thermal neutron-sensitive layer 2 located outside the moderation unit 1 and produce cascaded gamma rays. The cascaded gamma rays escape back into the moderation unit 1 and deposit energy. Theoretically, the time for the cascaded gamma rays to be generated and reach the moderation unit 1 is approximately the same as the time for the gamma rays in the gamma radiation field to reach the moderation unit 1. Therefore, the two can jointly produce the second scintillation light, which can finally be responded to by a photodetector. In this way, the neutron detector 100, composed of multiple moderation units 1, a thermal neutron sensitive layer 2, and multiple photodetectors, can distinguish neutrons and gamma rays by the number of responses of multiple photodetectors when detecting the analyte. On the one hand, it can simplify the detection steps, shorten the detection time, and reduce the occurrence of false judgments, thereby improving the detection accuracy of the analyte. On the other hand, it can reduce the interference of gamma rays in the gamma radiation field on the neutron detector 100, thereby improving the neutron-gamma discrimination ratio.

[0041] It should be noted that the neutron-gamma discrimination ratio is the ratio of neutron detection efficiency to gamma detection efficiency.

[0042] It should be noted that the gamma rays in the gamma radiation field mentioned here refer to high-energy gamma rays, such as gamma rays with energies greater than 300 keV.

[0043] Understandably, the misjudgment mentioned here refers to mistaking the slowing response induced by gamma rays in the gamma radiation field and the response induced by the photodetector as the response induced by the neutron being measured.

[0044] For example, in one embodiment, the shape of the slowing unit 1 is not limited, for example, it can be a cuboid, a cube or other shapes.

[0045] For example, in one embodiment, the photodetector can be a photomultiplier tube, such as a silicon photomultiplier tube. In this way, after receiving the first scintillator and the second scintillator, an electrical signal can be emitted. Finally, by detecting and analyzing the electrical signal, the type of particles emitted by the substance to be tested and the detection efficiency can be obtained.

[0046] For example, in one embodiment, the slowing unit 1 can be a plastic scintillator. This reduces the manufacturing cost of the neutron detector 100 and allows the slowing unit 1 to be processed into various shapes according to processing requirements. In some embodiments, the type of plastic scintillator is not limited; for example, it can be EJ-200. This improves the luminous efficiency of the first and second scintillators, facilitating photoelectric conversion by the photodetector, resulting in high accuracy and a high response rate. Of course, other types can also be used, such as EJ-204 or EJ-208, etc.

[0047] Understandably, moderation unit 1 moderates the neutrons to be tested using internal hydrogen atoms.

[0048] In one embodiment, for example, both ends of the slowing unit 1 along its length are coupled to a photodetector, which reduces light loss and improves the detection accuracy of the neutron detector 100.

[0049] In one embodiment, the neutron to be detected is a fast neutron. This facilitates the detection of some radioactive nuclear materials and offers high safety.

[0050] Fast neutrons are neutrons with energies between 0.1 MeV and 20 MeV.

[0051] A thermal neutron is a neutron with an energy of less than 1 keV.

[0052] In the prior art, the thermal neutron-sensitive layer 2 of the neutron detector 100 is... 3 He manages, and because 3 The shortage of He gas has led to soaring prices, which in turn has significantly increased the manufacturing cost of the neutron detector 100.

[0053] For example, in one embodiment, the material of the thermal neutron sensitive layer 2 can be... nat Gd₂O₃ (gadolinium oxide) has a low manufacturing cost. This is understandable. nat Gd2O3 155 Gd (60900 barns) and 157 Gd (25400 barns) has a very large thermal neutron reaction cross section, and therefore can be used for fast neutron detection.

[0054] In one embodiment, please refer to Figure 4The neutron detector 100 includes a reflective layer 3, and the outer peripheral surface of each slowing unit 1 is provided with a reflective layer 3. For example, if the slowing unit 1 is in the shape of a cuboid, the reflective layer 3 includes four of the six faces of the slowing unit 1, and the other two end faces are used for coupling to a photodetector. In this way, the first and second scintillation light scattered outward by the slowing unit 1 can be reflected back to the slowing unit 1 through the reflective layer 3 located outside the slowing unit 1, so as to avoid affecting the photodetectors of other slowing units 1 and causing false responses, thus improving detection accuracy.

[0055] For example, in one embodiment, the location of the reflective layer 3 is not limited. For instance, it can be disposed between the thermal neutron sensitive layer 2 and the moderation unit 1.

[0056] For example, in one embodiment, the reflective layer 3 may be Mylar, for example, an aluminized Mylar film.

[0057] In one embodiment, please refer to Figure 1 Multiple slowing units 1 are arranged along the width direction of the neutron detector 100 to form a slowing layer. For example, the number of slowing units 1 is not limited; for instance, there can be 16 units, and these 16 slowing units 1 are arranged along the width direction of the neutron detector 100 to form a slowing layer. Multiple slowing layers are stacked along the thickness direction of the neutron detector 100.

[0058] For example, in one embodiment, the incident surface of the neutron detector 100 is not limited. For instance, the incident surface can be one of the two sides along the thickness direction of the neutron detector 100. This increases the area for capturing gamma rays and neutrons in the gamma radiation field, resulting in high detection efficiency.

[0059] In one embodiment, the number of moderation layers is between 3 and 5. For example, the number of moderation layers is 4, which can improve the detection efficiency of the neutrons to be tested while saving costs.

[0060] In some embodiments, please refer to Figure 5 , Figure 5 The graph shows the relationship between the number of moderation layers and the detection efficiency of neutrons. It can be seen that when there are 1 to 3 moderation layers, the detection efficiency of neutrons increases exponentially with the increase of the number of moderation layers. When there are 3 to 5 moderation layers, the increase slows down. When there are more than 5 moderation layers, the detection efficiency of neutrons remains roughly unchanged. Therefore, when there are 1 to 3 moderation layers, the gamma radiation field and part of the neutrons being detected will directly penetrate through the multiple moderation layers due to the thin total thickness of the moderation layers, resulting in low detection efficiency and inaccurate detection. When the number of moderation layers reaches 5, the detection efficiency has reached its maximum. Increasing the number of layers further will lead to increased costs and poor economic efficiency.

[0061] In one embodiment, please refer to Figure 4 Each moderating unit 1 has a thermal neutron-sensitive layer 2 surrounding its outer periphery. For example, taking the moderating unit 1 as a cuboid, four of the six faces of each moderating unit 1 are wrapped by a thermal neutron-sensitive layer 2. In this way, thermal neutrons can be captured from multiple directions to improve the detection efficiency of the neutrons to be tested.

[0062] In some embodiments, please refer to Figure 6 , Figure 6 This graph shows the relationship between the thickness of the thermal neutron-sensitive layer 2 and the detection efficiency of the neutrons to be measured. The horizontal axis represents the thickness of the thermal neutron-sensitive layer 2, and the vertical axis represents the detection efficiency. The curves with squares represent the relationship between the detection efficiency of the thermal neutron-sensitive layer 2 surrounding the outer periphery of each moderation unit 1 and the thermal neutron-sensitive layer 2. Figure 6 As can be seen from the data, the detection efficiency of the neutrons to be measured is highest when the outer periphery of each moderation unit 1 is surrounded by a thermal neutron-sensitive layer 2.

[0063] In one embodiment, please refer to Figure 4 The neutron detector 100 includes a first protective layer 4, which surrounds the outer peripheral surface of the thermal neutron sensitive layer 2. For example, the first protective layer 4 is disposed on the surface of the thermal neutron sensitive layer 2 away from the reflective layer 3, thus protecting the thermal neutron sensitive layer 2 from scratches that could affect detection accuracy.

[0064] For example, in one embodiment, the first protective layer 4 may be made of Tedlar (polyvinyl fluoride).

[0065] In one embodiment, a thermal neutron-sensitive layer 2 is laid between two of the multiple moderation layers. For example, taking a four-layer moderation layer as an example, a thermal neutron-sensitive layer 2 can be placed between two of the four layers, which can reduce the amount of thermal neutron-sensitive layer 2 used and save costs.

[0066] In one embodiment, please refer to Figure 1 and Figure 2 A thermal neutron-sensitive layer 2 is laid between every two adjacent moderation layers. For example, taking a 4-layer moderation layer as an example, a thermal neutron-sensitive layer 2 can be laid between every two adjacent layers in the 4-layer moderation layer. That is, 3 thermal neutron-sensitive layers 2 are laid in the 4-layer moderation layer. In this way, the amount of thermal neutron-sensitive layer 2 can be reduced while ensuring a suitable detection efficiency of the neutrons to be measured.

[0067] As an example, in one embodiment, please refer to Figure 6The placement of the thermal neutron-sensitive layer 2 can be selected according to the required detection efficiency of the neutrons to be measured. For example, for scenarios with high requirements for neutron detection efficiency, a placement method in which a thermal neutron-sensitive layer 2 surrounds the outer periphery of each moderation unit 1 can be selected; for scenarios requiring reduced usage costs, a placement method in which one thermal neutron-sensitive layer 2 is laid among multiple moderation layers can be selected; for scenarios requiring both usage costs and neutron detection efficiency, a placement method in which one thermal neutron-sensitive layer 2 is laid between every two adjacent moderation layers can be selected. This offers a high degree of selectivity.

[0068] In one embodiment, the thickness of the thermal neutron-sensitive layer 2 is between 20 μm and 30 μm. For an example, please refer to [link to example]. Figure 6 , Figure 6 The middle section represents three different placement methods for the thermal neutron sensitive layer 2, from... Figure 6 As can be seen, when the thickness of the thermal neutron sensitive layer 2 can be between 20μm and 30μm, such as 25μm, the detection efficiency of the neutron to be measured can be improved while taking into account the cost. For example, if the outer periphery of each moderation unit 1 is surrounded by a thermal neutron sensitive layer 2, the detection efficiency of the neutron to be measured can reach about 65% when the thermal neutron sensitive layer 2 is 25μm. Another example is that if a thermal neutron sensitive layer 2 is laid between every two adjacent moderation layers, the detection efficiency of the neutron to be measured can reach about 55% when the thermal neutron sensitive layer 2 is 25μm. Yet another example is that if a thermal neutron sensitive layer 2 is laid between two of the multi-layer moderation layers, the detection efficiency of the neutron to be measured can reach about 47% when the thermal neutron sensitive layer 2 is 25μm.

[0069] It is understood that the thickness of the thermal neutron sensitive layer 2 mentioned here refers to the thickness of a single layer, not the total thickness of the thermal neutron sensitive layer 2. Taking a four-layer moderation layer with each thermal neutron sensitive layer 2 being 25 μm as an example, if the outer periphery of each moderation unit 1 is surrounded by a thermal neutron sensitive layer 2, the total thickness of the thermal neutron sensitive layer 2 is 200 μm. If a thermal neutron sensitive layer 2 is laid between two of the multi-layer moderation layers, the total thickness of the thermal neutron sensitive layer 2 is 25 μm. If a thermal neutron sensitive layer 2 is laid between every two adjacent moderation layers, the total thickness of the thermal neutron sensitive layer 2 is 75 μm.

[0070] In one embodiment, please refer to Figure 3 The neutron detector 100 includes a second protective layer 5, which is provided on the outer peripheral surface of each moderation unit 1. This protects the thermal neutron-sensitive layer 2 from scratches that could affect detection accuracy.

[0071] For example, in one embodiment, the material of the second protective layer 5 may be polyvinyl fluoride.

[0072] In one embodiment, the neutron detector 100 includes lead plates, with one lead plate disposed between each pair of adjacent moderating layers. This effectively shields gamma rays from the gamma-scattered gamma radiation field, further improving the neutron-gamma discrimination ratio. Taking the placement of a thermal neutron-sensitive layer 2 surrounding the outer periphery of each moderating unit 1 as an example, the neutron-gamma discrimination ratio is 390 without lead plates; after placing lead plates, the neutron-gamma discrimination ratio can reach 802, which can greatly reduce the impact of gamma rays in the gamma radiation field on the detection efficiency of the neutron to be tested.

[0073] In one embodiment, the thickness of the lead plate is not limited; for example, the thickness of each layer of lead plate can be 3 mm.

[0074] Another aspect of this application provides a neutron detection method; please refer to [link to relevant documentation]. Figure 7 The neutron detector 100 used in any of the above embodiments includes a detection method comprising:

[0075] S1. Set a first number of the slowing units in response to gamma rays in the gamma radiation field as a threshold.

[0076] S2. If the total number of responses from the moderation units is greater than the threshold, it is determined that the substance to be tested contains the neutron to be tested.

[0077] This embodiment sets the first number of slowing units 1 responding to gamma rays in the gamma radiation field as a threshold. When the total number of responses from slowing units 1 is greater than the threshold, it is determined that the analyte contains the neutron to be tested. On the one hand, this simplifies the detection steps, reduces detection time, and decreases the occurrence of false positives, thereby improving the detection accuracy of the neutron to be tested. On the other hand, it also reduces the impact of gamma rays in the gamma radiation field on the detection efficiency of the neutron to be tested, thereby improving the neutron-gamma discrimination ratio.

[0078] In one embodiment, the threshold is between 2 and 4. For example, the threshold can be 3; please refer to [link / reference needed]. Figure 8 , Figure 8 The graph shows the relationship between the number of responses from moderation unit 1 and the number of signals. The horizontal axis represents the number of responses from moderation unit 1, and the vertical axis represents the number of signals emitted by the photodetector after detecting gamma rays in the neutron and gamma radiation field. Figure 8 It can be seen that the number of responses of moderation unit 1 caused by the incident neutron is about 1 to 14, and the number of responses of moderation unit 1 caused by gamma rays in the gamma radiation field is about 1 to 4. After setting the threshold to 3, most of the gamma ray signals in the gamma radiation field can be blocked, thereby improving the neutron-gamma discrimination ratio.

[0079] For example, in one embodiment, most of the gamma-ray signals in the gamma radiation field can be shielded by controlling the number of responses of the photodetector.

[0080] It should be noted that since each slowing unit 1 is connected to two photodetectors, it can only be determined that the slowing unit 1 has responded if both photodetectors corresponding to each slowing unit 1 respond. For example, if the number of responses of slowing unit 1 is between 2 and 4, then the number of responses of the corresponding photodetectors is between 4 and 8. In this way, the influence of gamma rays in the gamma radiation field on the detection can be reduced, thereby improving the detection accuracy.

[0081] The above description is merely a preferred embodiment of this application and is not intended to limit the application. Various modifications and variations can be made to this application by those skilled in the art. All modifications, equivalent substitutions, improvements, etc., within the spirit and principles of this application are included within the scope of protection of this application.

Claims

1. A neutron detector, characterized in that, include: Multiple moderation units are used, and the neutrons to be tested in the analyte can be slowed down by the moderation units to produce thermal neutrons; A thermal neutron-sensitive layer is disposed outside the moderator unit. The thermal neutrons are captured by the thermal neutron-sensitive layer to generate cascaded gamma rays. The gamma rays in the gamma radiation field induce a first number of the moderator units to respond. The gamma rays in the gamma radiation field and the cascaded gamma rays together induce a second number of the moderator units to respond. The neutron detector sets a first number of slowing units responding to gamma rays in the gamma radiation field as a threshold, and determines that the analyte contains the analyte neutron when a second number of slowing units responds to the threshold.

2. The neutron detector according to claim 1, characterized in that, The neutron detector includes multiple photodetectors, and each of the slowing units is coupled to at least one of the photodetectors.

3. The neutron detector according to claim 1, characterized in that, The neutron detector includes a reflective layer, and the reflective layer is disposed on the outer peripheral surface of each of the slowing units.

4. The neutron detector according to claim 1, characterized in that, Multiple moderating units are arranged along the width direction of the neutron detector to form a moderating layer, and multiple moderating layers are stacked along the thickness direction of the neutron detector.

5. The neutron detector according to claim 4, characterized in that, Each of the moderating units is surrounded by a thermal neutron-sensitive layer on its outer periphery.

6. The neutron detector according to claim 5, characterized in that, The neutron detector includes a first protective layer, and the outer peripheral surface of the thermal neutron sensitive layer is surrounded by the first protective layer.

7. The neutron detector according to claim 4, characterized in that, A thermal neutron-sensitive layer is laid between two of the multiple moderating layers, or... Each pair of adjacent moderating layers is covered with a thermal neutron-sensitive layer.

8. The neutron detector according to claim 7, characterized in that, The neutron detector includes a second protective layer, and each of the slowing units has a second protective layer on its outer peripheral surface.

9. The neutron detector according to claim 4, characterized in that, The neutron detector includes lead plates, with one lead plate disposed between each two adjacent moderating layers.

10. The neutron detector according to claim 4, characterized in that, The number of moderating layers is between 3 and 5.

11. The neutron detector according to claim 1, characterized in that, The thickness of the thermal neutron sensitive layer is between 20 μm and 30 μm.

12. A neutron detection method, characterized in that, The detection method for the neutron detector according to any one of claims 1 to 11 comprises: The first number of the slowing units in response to gamma rays in the gamma radiation field is set as a threshold. If the second response quantity of the moderation unit is greater than the threshold, it is determined that the analyte contains the analyte neutron.

13. The detection method according to claim 12, characterized in that, The threshold is between 2 and 4.

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