A method, device and system for detecting adulteration of materials

Abstract

The present invention provides a detection method, device and system for solid material doping, the method comprising: obtaining a first intensity of fast neutrons before transmission through the material to be detected and a second intensity after transmission, as well as gamma spectrum data of the material to be detected; obtaining a neutron macroscopic cross section of the material to be detected according to the first intensity and the second intensity; judging whether there is doping according to the neutron macroscopic cross section of the material to be detected and the neutron macroscopic cross section of the preset undoped material; obtaining the element category and content in the material to be detected according to the gamma spectrum data of the material to be detected. The method realizes quantitative non-destructive judgment of the doping of the solid material to be detected, quickly judges whether there is the possibility of doping in the material by detecting the change of the fast neutron penetration yield, and performs a more in-depth analysis based on the gamma spectrum data; the detection process is fully automatic, without human intervention, avoiding many shortcomings of manual inspection.

Description

Technical Field

[0001] The present invention relates to the technical field of material detection, and in particular to a method, device and system for detecting adulteration of materials. Background Art

[0002] For common solid materials such as scrap steel and ore, doping will affect the quality and performance of scrap steel and ore, and doping substances will produce harmful gases or affect the melting characteristics of the charge during the smelting process. Harmful gases released into the environment will cause environmental pollution and increase industrial safety risks; doping substances that affect the melting characteristics of the charge will interfere with the smelting process, resulting in reduced production efficiency and increased energy consumption and costs. Testing for doping in solid materials can ensure that the materials meet specific industrial standards and requirements.

[0003] Taking the recycling of scrap steel as an example, there are many types of scrap steel materials, and the common categories are conventional bulk materials, crushed materials, pig iron, crushed briquettes, and industrial briquettes. For conventional bulk materials and crushed materials, manual random sampling and spot checks are generally used for bulk density and screening tests; for pig iron, manual random sampling and component analysis are generally used. The component analysis process takes about 2 days and the inspection cycle is long; for crushed briquettes (such as crushed briquettes and shavings briquettes), water output rate is generally used for inspection and calculation. This inspection method is relatively expensive. For example, the inspection cost of 1 ton of medium frequency furnace smelting is more than 5,000 yuan each time, and this inspection method determines that batch inspection cannot be carried out, and only random inspection mode can be used.

[0004] Industrial briquette scrap steel accounts for the largest proportion, about 60%. The sources of this type of scrap steel are complex and the types are numerous. Manual inspection cannot be effectively quantified. The quality of the inspection results depends on the personal skills and sense of responsibility of the inspectors, and there are no prescriptive judgment standards. In recent years, various steel mills have had cases of scrap steel inspections violating regulations and infringing on the interests of the company. The processing and inspection methods of briquette scrap steel have led to some illegal suppliers easily developing a game mentality. Most of the false cases of scrap steel adulteration discovered in recent years have occurred in briquette scrap steel.

[0005] Regardless of the type of scrap steel, manual sampling always carries the risk of insufficient sample representativeness, and the testing process is heavily dependent on human experience, with many subjective factors, difficult management, and the test results are not accurate and objective. Summary of the invention

[0006] In view of the above defects in the prior art, the present invention provides a method, device and system for detecting adulteration of materials to solve the technical problems of inaccuracy, objectivity and difficulty in manual adulteration detection.

[0007] To achieve the above-mentioned purpose and other related purposes, the present invention provides a method for detecting doping of materials, comprising: obtaining a first intensity of fast neutrons before transmission of the material to be detected and a second intensity after transmission, and also obtaining gamma spectrum data of the material to be detected; obtaining a neutron macroscopic cross-section of the material to be detected based on the first intensity and the second intensity; judging whether there is doping based on the neutron macroscopic cross-section of the material to be detected and the neutron macroscopic cross-section of a preset undoped material; and obtaining the type and content of elements in the material to be detected based on the gamma spectrum data of the material to be detected.

[0008] In one embodiment of the present invention, the neutron macroscopic cross section of the material to be detected is calculated according to the following formula: , where I 0 is the first intensity, I is the second intensity, is the neutron macroscopic cross section of the material to be detected, and t is the thickness of the material to be detected.

[0009] In one embodiment of the present invention, judging whether there is doping based on the neutron macroscopic cross-section of the material to be detected and the neutron macroscopic cross-section of a preset undoped material includes: obtaining a neutron macroscopic cross-section difference based on the neutron macroscopic cross-section of the material to be detected and the neutron macroscopic cross-section of the preset undoped material; judging whether the neutron macroscopic cross-section difference is greater than the product of the neutron macroscopic cross-section of the undoped material and a preset ratio: if yes, there is doping in the material to be detected; if no, there is no doping in the material to be detected.

[0010] In one embodiment of the present invention, the type and content of elements in the material to be detected are obtained based on the gamma energy spectrum data of the material to be detected, including: obtaining an energy spectrum diagram based on the gamma energy spectrum data of the material to be detected; obtaining the type of elements in the material to be detected based on characteristic peaks in the energy spectrum diagram; and analyzing the energy spectrum diagram using the Monte Carlo library least squares method to obtain the content of each element in the material to be detected.

[0011] To achieve the above-mentioned purpose and other related purposes, the present invention also provides a device for detecting doping of materials, comprising: a data acquisition unit, used to obtain a first intensity of fast neutrons before transmission of the material to be detected and a second intensity after transmission, and also to obtain gamma spectrum data of the material to be detected; a calculation unit, used to obtain the neutron macroscopic cross-section of the material to be detected based on the first intensity and the second intensity; a judgment unit, used to judge whether there is doping based on the neutron macroscopic cross-section of the material to be detected and the neutron macroscopic cross-section of a preset undoped material; an analysis unit, used to obtain the type and content of elements in the material to be detected based on the gamma spectrum data of the material to be detected.

[0012] To achieve the above-mentioned purpose and other related purposes, the present invention also provides a system for detecting doping of materials, comprising: a neutron source, arranged on one side of the material to be detected, for generating fast neutrons; a first moderator, arranged between the neutron source and the material to be detected, for moderating the fast neutrons to obtain thermal neutrons; a neutron detector, for detecting fast neutrons after transmitting the material to be detected; a gamma detector, for detecting gamma rays generated by the reaction of the thermal neutrons with the material to be detected; a control unit, for controlling the neutron source, receiving detection data from the neutron detector and the gamma detector, and detecting the material to be detected according to the method as described above; and a shielding unit, for shielding the detection area.

[0013] In one embodiment of the present invention, the control module includes: an instruction issuing unit, used to issue instructions to the neutron source to control the neutron source to generate fast neutrons according to the instructions; a data processing unit, used to calculate the intensity of the fast neutrons emitted by the neutron source according to the instructions to obtain the first intensity; a first digital multi-channel board, used to process the detection data received from the neutron detector to obtain the second intensity; a second digital multi-channel board, used to process the detection data received from the gamma detector to obtain the gamma energy spectrum data; and a doping detection device, used to detect the material to be detected.

[0014] In one embodiment of the present invention, the system also includes a conveyor belt; the material to be detected is located on the conveyor belt; the neutron source is arranged above the material to be detected or below the conveyor belt; the neutron detector is arranged on the side of the material to be detected away from the neutron source; the gamma detector is arranged on the side and / or above the material to be detected.

[0015] In one embodiment of the present invention, the shielding unit includes a second moderator and graphite; the second moderator is arranged on both sides of the material to be detected in the conveying direction of the conveyor belt; the first moderator is arranged above the material to be detected, and the graphite is arranged on the upper side of the first moderator, and a recess is provided on the side of the graphite facing the first moderator for installing the neutron source.

[0016] In one embodiment of the present invention, the plate body of the first moderator plate located at the graphite recess is thinner than that at other positions, so that the neutrons passing through the first moderator plate include both fast neutrons and thermal neutrons.

[0017] Beneficial effects of the present invention: The present invention proposes a method, device and system for detecting doping in materials. The method adopts a new neutron activation analysis technology to realize quantitative and non-destructive judgment of the doping status of the material to be detected. On the one hand, based on the physical quantity of neutron macroscopic cross-section, the change of the penetration yield of fast neutrons is detected, and this is used to quickly judge whether there is a possibility of doping in the material. On the other hand, a more in-depth analysis is performed based on gamma energy spectrum data to obtain the type and content of elements in the material to be detected; at the same time, the detection process is fully automatic, without human intervention, avoiding many shortcomings of manual inspection. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 A flowchart of a doping detection method provided by an embodiment of the present invention;

[0020] Figure 2 A comparison chart of neutron penetration monitoring of pure iron and materials doped with different proportions provided in one embodiment of the present invention;

[0021] Figure 3 A doping determination flow chart provided in accordance with an embodiment of the present invention;

[0022] Figure 4 A processing flow chart for gamma spectrum provided by an embodiment of the present invention;

[0023] Figure 5 A comparison diagram of gamma spectra of pure iron and materials doped in different proportions provided in one embodiment of the present invention;

[0024] Figure 6 A schematic diagram of a doping detection device provided by an embodiment of the present invention;

[0025] Figure 7 A block diagram of a doping detection system provided by an embodiment of the present invention;

[0026] Figure 8 A schematic structural diagram of a first doping detection system provided by an embodiment of the present invention;

[0027] Fig. 9 A schematic structural diagram of a second doping detection system provided in one embodiment of the present invention.

[0028] Explanation of the reference numerals: 100, neutron source; 200, first moderator plate; 300, neutron detector; 400, gamma detector; 500, control module; 510, instruction issuing unit; 520, data processing unit; 530, first digital multi-channel plate; 540, second digital multi-channel plate; 550, doping detection device; 551, data acquisition unit; 552, calculation unit; 553, judgment unit; 554, analysis unit; 600, shielding unit; 601, second moderator plate; 602, graphite; 700, conveyor belt. DETAILED DESCRIPTION

[0029] The following describes the embodiments of the present invention through specific specific embodiments, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. It should be noted that the following embodiments and the features in the embodiments can be combined with each other without conflict. In addition to the specific methods, equipment, and materials used in the embodiments, according to the technical personnel in this technical field's grasp of the prior art and the records of the present invention, any methods, equipment, and materials of the prior art that are similar or equivalent to the methods, equipment, and materials described in the embodiments of the present invention can also be used to implement the present invention.

[0030] It should be understood that the terms used in the embodiments of the present invention are for describing specific embodiments rather than for limiting the scope of protection of the present invention. Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as those generally understood by those skilled in the art.

[0031] The structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions under which the present invention can be implemented, so they have no substantive technical significance. Any modification of the structure, change in the proportional relationship, or adjustment of the size should still fall within the scope of the technical content disclosed by the present invention without affecting the effects and purposes that can be achieved by the present invention. In addition, the drawings only show the components related to the present invention rather than the number, shape, and size of the components in actual implementation. The type, quantity, and proportion of each component in actual implementation can be changed arbitrarily, and the component layout type may also be more complicated.

[0032] In the following description, numerous details are discussed to provide a more thorough explanation of the embodiments of the present invention. However, it is obvious to those skilled in the art that the embodiments of the present invention can be implemented without these specific details. In some of the embodiments, well-known structures and devices are shown in the form of block diagrams rather than in detail to avoid making the embodiments of the present invention difficult to understand.

[0033] The flowchart and block diagram in the accompanying drawings illustrate the system architecture, functions and operations that may be implemented according to the methods and computer program products of various embodiments disclosed in the present invention. In this regard, each box in the flowchart or block diagram can represent a module, a program segment, or a part of a code, and the module, the program segment, or a part of the code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in a different order from the order marked in the accompanying drawings. For example, two boxes represented in succession can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram and / or the flowchart, and the combination of the boxes in the block diagram and / or the flowchart can be implemented with a dedicated hardware-based system that performs the specified function or operation, or can be implemented with a combination of dedicated hardware and computer instructions.

[0034] See also Figure 1 , Figure 1 A method for detecting adulteration of materials provided in an embodiment of the present invention includes steps S100 to S400.

[0035] Step S100, obtain the first intensity of the fast neutron before it penetrates the material to be detected and the second intensity after it penetrates, and also obtain the gamma spectrum data of the material to be detected. For the first intensity, the intensity of the fast neutrons emitted by the neutron source 100 can be obtained, and the intensity of the fast neutrons after passing through the first moderator plate 200 can also be obtained, as long as it is before penetrating the material to be detected. When obtaining the first intensity data, it can be obtained through the neutron detector 300, or the corresponding intensity can be calculated according to the control instruction of the neutron source 100. For the second intensity, this is detected by the detector placed in the area after the neutron penetrates the material to be detected. Here, a neutron detector 300 must be set for detection. Therefore, in this step, at least one neutron detector 300 must be set. For the gamma spectrum data, it is necessary to use a gamma detector 400 for detection.

[0036] For the neutron detector 300, since neutrons themselves are not charged and cannot directly cause ionization or excitation, it is necessary to detect secondary particles generated by the interaction between neutrons and other substances. These secondary particles can be charged particles, such as protons, alpha particles, etc., which produce gas ionization when moving in the gas, and the neutron fluence rate level is determined by measuring the gas ionization amount. The signal output by the neutron detector 300 is usually an electrical signal, which needs to be converted before it can be obtained.

[0037] For the gamma detector 400, secondary particles or radiation generated by the interaction between gamma rays and the detector material can be measured by photoelectric conversion through the detector. The signal output by the gamma detector 400 is also usually an electrical signal, which also needs to be converted before it can be obtained.

[0038] In this step, the material to be tested can be a solid material (such as the iron block and ore below), or a liquid, bottled gas, fluid, etc.

[0039] Step S200: Obtain the neutron macroscopic cross section of the material to be detected according to the first intensity and the second intensity. Fast neutrons can penetrate thicker materials, such as iron blocks, ores, etc., due to their high energy. After penetrating the material, fast neutrons can be detected by fast neutron detectors. Since different elements have different neutron cross sections and different neutron attenuation coefficients, the neutron penetration yield will change in the presence of inclusions, and these changes can be reflected in the neutron macroscopic cross section of the material.

[0040] Neutron macroscopic cross-section is an important concept in nuclear reaction physics, which describes the probability of a specific reaction between all nuclei and neutrons in a unit volume per unit time. Neutron macroscopic cross-section is an average value, which combines the microscopic cross-section of all individual nuclei and the number density of nuclei (number of nuclei / unit volume). The unit of neutron macroscopic cross-section is usually square meters, because it is the result of the geometric cross-section of the nucleus multiplied by the number density of the nucleus.

[0041] The neutron macroscopic cross section can be used to calculate the macroscopic behavior of neutrons when propagating in materials, such as the change in neutron attenuation length and neutron flux. In this embodiment, using neutron activation analysis technology, different elements have different neutron macroscopic cross sections, which makes it possible to analyze whether the material is doped by measuring the neutron penetration yield. The calculation process is relatively simple compared to energy spectrum analysis, so it is very fast to process.

[0042] In a specific embodiment of the present invention, the neutron macroscopic cross section of the material to be detected is calculated according to the following formula:

[0043] ,

[0044] In the formula, I 0 is the first intensity, I is the second intensity, is the neutron macroscopic cross section of the material to be detected, and t is the thickness of the material to be detected. The second intensity I and the first intensity I 0 The ratio is a neutron macroscopic cross section of the material to be tested at the same time scale. Therefore, by calculating this ratio, the neutron macroscopic cross section of the material to be tested can be obtained. The value of can then quickly analyze whether there is any adulteration in the material. The thickness t here generally refers to the average thickness of the material to be tested. If the thickness of the material to be tested is uneven, it usually needs to be smoothed.

[0045] Step S300, judging whether there is doping according to the neutron macroscopic cross section of the material to be detected and the preset neutron macroscopic cross section of the undoped material. For example, when the material to be detected is an iron block, the neutron macroscopic cross section data of undoped pure iron can be first collected as a preset value for reference. Later, when it is necessary to judge whether there is doping, it is only necessary to compare the neutron macroscopic cross section of the iron block to be detected with the preset value. As long as the neutron macroscopic cross section changes, the possibility of doping of the scrap iron block can be immediately determined. Figure 2 This is a comparison chart of neutron penetration monitoring of pure iron and materials doped with different proportions. It can be seen from the figure that when there is no doping, the neutron penetration yield of each energy range is shown as the blue curve in the figure. When there is doping, it shows other forms according to the different doping ratios, as shown by the other color curves in the figure. The higher the doping ratio, the lower the neutron penetration yield.

[0046] See also Figure 3 In a specific embodiment of the present invention, step S300 includes step S301 and step S302.

[0047] Step S301: Obtain a neutron macroscopic cross section difference according to the neutron macroscopic cross section of the material to be detected and the preset neutron macroscopic cross section of the undoped material. The neutron macroscopic cross section difference corresponds to the neutron macroscopic cross section corresponding to the doping.

[0048] Step S302, determine whether the neutron macroscopic cross-section difference is greater than the product of the neutron macroscopic cross-section of the undoped material and the preset ratio: if yes, there is doping in the material to be detected; if no, there is no doping in the material to be detected. Theoretically, the neutron macroscopic cross-section difference should be 0, indicating that there is no doping in the material to be detected, but considering that there will be errors during detection, a preset ratio is introduced and multiplied by the neutron macroscopic cross-section of the undoped material, and the product of the two is used as the difference for comparison.

[0049] Step S400: Obtain the type and content of elements in the material to be detected based on the gamma spectrum data of the material to be detected.

[0050] After being slowed down by the first moderator plate 200, fast neutrons become thermal neutrons, which react with the material to be detected to release characteristic gamma rays. The gamma energy range is usually 0~10MeV. The energy of the gamma rays is related to the type of nuclide, and the intensity of the rays is related to the content of the material. The released gamma rays are detected by one or more gamma detectors 400, and after photoelectric conversion, the gamma energy spectrum data can be obtained.

[0051] See also Figure 4 In a specific embodiment of the present invention, step S400 includes steps S401 to S403.

[0052] Step S401: Obtain an energy spectrum diagram based on the gamma spectrum data of the material to be tested. By analyzing the gamma spectrum data, an energy spectrum diagram can be obtained. The energy spectrum diagram is as follows: Figure 5 As shown, Figure 5 The figure shows the gamma energy spectrum comparison between pure iron and materials doped in different proportions. It can be seen that the energy spectra have obvious differences under different doping ratios.

[0053] Step S402: Obtain the element category in the material to be tested based on the characteristic peaks in the energy spectrum. Step S403: Analyze the energy spectrum using the Monte Carlo library least squares method to obtain the content of each element in the material to be tested. Through these two steps, the category and content of the elements in the material to be tested can be further calculated, wherein all elements other than the main element (such as iron in an iron block) can be regarded as doping.

[0054] Step S403 may include the following steps: (1) Model building: Assume that the energy spectrum contains characteristic peaks of multiple elements, and the characteristic peak of each element can be represented by a Gaussian function or other forms of functions; (2) Least squares fitting: Use the least squares method to fit the energy spectrum data, minimize the square difference between the observed data and the model prediction, and estimate the concentration and characteristic peak position of each element; (3) Result analysis: The parameters obtained by fitting can be used to determine the concentration of each element in the sample and analyze its performance in the energy spectrum. The advantage of the Monte Carlo library least squares method is that it can process complex energy spectrum data and provide accurate element analysis results.

[0055] It should be noted that the step division of the above methods is only for clear description. When implemented, they can be combined into one step or some steps can be split and decomposed into multiple steps. As long as they contain the same logical relationship, they are all within the scope of protection of this patent; adding insignificant modifications to the algorithm or process or introducing insignificant designs without changing the core design of the algorithm and process are all within the scope of protection of this patent.

[0056] See also Figure 6 , Figure 6A device for detecting doping of materials provided in one embodiment of the present invention includes a data acquisition unit 551, a calculation unit 552, a judgment unit 553 and an analysis unit 554. The data acquisition unit 551 is used to obtain a first intensity of fast neutrons before they penetrate the material to be detected and a second intensity after they penetrate, and also obtains gamma spectrum data of the material to be detected; the calculation unit 552 is used to obtain a neutron macroscopic cross section of the material to be detected based on the first intensity and the second intensity; the judgment unit 553 is used to determine whether there is doping based on the neutron macroscopic cross section of the material to be detected and the neutron macroscopic cross section of the preset undoped material; the analysis unit 554 is used to obtain the type and content of elements in the material to be detected based on the gamma spectrum data of the material to be detected.

[0057] It should be noted that the doping detection device of this embodiment is a device corresponding to the above-mentioned doping detection method, and the functional modules in the doping detection device may correspond to the corresponding steps in the doping detection method. The doping detection device of this embodiment can be implemented in coordination with the doping detection method, that is, in the absence of conflict, the relevant technical details mentioned in the doping detection method of the above-mentioned embodiment can also be applied to the doping detection device of this embodiment.

[0058] It should be noted that the above-mentioned functional modules can be fully or partially integrated into one physical entity during actual implementation, or they can be physically separated. And these modules can all be implemented in the form of software called by processing elements; they can also be all implemented in the form of hardware; some modules can also be implemented in the form of software called by processing elements, and some modules can be implemented in the form of hardware. In addition, these modules can be fully or partially integrated together, or they can be implemented independently. The processing element described here can be an integrated circuit with signal processing capabilities. In the implementation process, some or all of the steps of the above method, or the above functional modules can be completed by hardware integrated logic circuits in the processor element or instructions in software form.

[0059] See also Figure 7 , Figure 7 A system for detecting doping of materials provided in one embodiment of the present invention includes a neutron source 100 , a first moderator plate 200 , a neutron detector 300 , a gamma detector 400 , a control module 500 and a shielding unit 600 .

[0060] The neutron source 100 is arranged on one side of the material to be detected and is used to generate fast neutrons. The neutron source 100 can be a chemical source, such as Cf252 (Californium-252), or a neutron generator can be directly selected. When the neutron source 100 is a neutron generator, a gas cylinder provides gas to the ion source chamber, and the gas forms plasma to generate ions after microwave discharge. The ions are accelerated and high-voltage extracted and adsorbed on the target. The ions injected later react with the ions previously adsorbed on the target to generate fast neutrons.

[0061] The first moderator plate 200 is disposed between the neutron source 100 and the material to be detected, and is used to moderate the fast neutrons to obtain thermal neutrons. The thickness of the first moderator plate 200 needs to be set as required so that the moderated neutrons include both fast neutrons and thermal neutrons.

[0062] The neutron detector 300 is used to detect fast neutrons after penetrating the material to be detected. The neutron detector 300 is a device used to detect and measure neutrons. They can convert the signals generated by the interaction between neutrons and matter into readable data. The working principle of the neutron detector 300 is mainly based on the interaction between neutrons and detector materials to achieve neutron detection. In this embodiment, the neutron detector 300 is a fast neutron detector, which is specially used to detect high-energy neutrons.

[0063] The gamma detector 400 is used to obtain gamma energy spectrum data of the material to be detected. Figure 8 In the structure, since the object to be detected is an iron block, in order to overcome the self-shielding problem of activated gamma photons and effectively improve the detection range of the gamma detector 400, multiple gamma detectors 400 (for example, two) can be set and placed on both sides of the iron block. Fig. 9 In the structure, when the material to be detected is conventional bulk material or crushed material, the gamma detector 400 can be arranged above the material to be detected, and the gamma detector 400 can detect the gamma rays reflected by the material.

[0064] The control module 500 is used to control the neutron source 100, receive detection data from the neutron detector 300 and the gamma detector 400, and detect the material to be detected according to the above-mentioned doping detection method.

[0065] The shielding unit 600 is used to shield the detection area. When using neutrons for detection, shielding measures are usually necessary. The main reasons are: (1) Protecting personnel safety: Neutrons are high-energy particles that can penetrate human tissue and cause radiation damage. Proper shielding can reduce the radiation dose received by operators and surrounding personnel and protect them from radiation damage; (2) Reducing background noise: In the neutron detection environment, there may be background radiation generated by natural radioactivity or other radiation sources. Shielding can help reduce this background radiation and improve the accuracy and reliability of detection; (3) Improving detection accuracy: Proper shielding can reduce the interference of non-target neutrons and improve the accuracy and resolution of detection; etc.

[0066] The choice of shielding material depends on many factors, including the energy of the neutrons, the specific requirements of the detection, cost and availability. Common shielding materials include concrete, lead, water, paraffin, polyethylene and boric acid. Each material has its own specific shielding properties and is suitable for different neutron energy ranges and application scenarios. When designing a shielding system, these factors need to be considered comprehensively to ensure that it is both effective and economical.

[0067] In a specific embodiment of the present invention, the control module 500 includes an instruction issuing unit 510, a data processing unit 520, a first digital multi-channel board 530, a second digital multi-channel board 540 and a doping detection device 550. Among them, the instruction issuing unit 510 is used to issue instructions to the neutron source 100 to control the neutron source 100 to generate fast neutrons according to the instructions; the data processing unit 520 is used to calculate the intensity of the fast neutrons emitted by the neutron source 100 according to the instructions to obtain a first intensity; the first digital multi-channel board 530 is used to process the detection data received from the neutron detector 300 to obtain a second intensity; the second digital multi-channel board 540 is used to process the detection data received from the gamma detector 400 to obtain gamma energy spectrum data; the doping detection device 550 is used to detect the material to be detected, such as Figure 6 shown.

[0068] In a specific embodiment of the present invention, two neutron detectors 300 are provided, one is provided before the material to be detected is transmitted, for example, it can be provided at the neutron source 100 or the first moderator 200, and the other is provided after the material to be detected is transmitted. At this time, the control module 500 includes an instruction issuing unit 510, two first digital multi-channel boards 530, a second digital multi-channel board 540 and a doping detection device 550. The two first digital multi-channel boards 530 respectively process the detection data received from the two neutron detectors 300 to obtain the first intensity and the second intensity. The functions of other components refer to the previous embodiment.

[0069] In a specific embodiment of the present invention, the system also includes a conveyor belt 700. The material to be detected is located on the conveyor belt 700, so that continuous detection of the material can be achieved. In actual application, other components can be directly deployed on the conveyor belt 700 (that is, the conveyor belt 700 will pass through other components). In this structure, the neutron source 100 can be set above the material to be detected or below the conveyor belt 700; the neutron detector 300 is set on the side of the material to be detected away from the neutron source 100; the gamma detector 400 is set on the side and / or above the material to be detected, and the front and rear of the material to be detected form a material transmission channel. For example, in Figure 8 In the structure, the gamma detector 400 is arranged on the side. Fig. 9 The middle one is set at the top.

[0070] In a specific embodiment of the present invention, the shielding unit 600 includes a second moderator plate 601 and graphite 602; the second moderator plate 601 is arranged on both sides of the material to be detected in the conveying direction of the conveyor belt 700; the first moderator plate 200 is arranged above the material to be detected, and the graphite 602 is arranged on the upper side of the first moderator plate 200, and a recess is provided on the side of the graphite 602 facing the first moderator plate 200 for installing the neutron source 100. Graphite 602 is arranged on the top of the first moderator plate 200 to reflect neutrons and improve neutron utilization. In addition to the second moderator plate 601 and graphite 602, other shielding components can also be arranged.

[0071] The moderator plate (whether the first moderator plate 200 or the second moderator plate 601) is mainly used for scattering and moderating neutrons. The constituent materials of the moderator plate may include, for example, water, paraffin, polyethylene, metal materials (such as various types of stainless steel, tungsten, copper, etc.), composite concrete (such as boron-containing cement, polyethylene-containing cement, etc.), polymer compounds, rare earth polymer materials, fiber fabrics, shielding materials or nanomaterials treated by surface treatment technology, etc. The moderator plate is used for scattering and moderating neutrons. They can reduce the energy of neutrons and convert them from high-energy fast neutrons to low-energy thermal neutrons.

[0072] In this embodiment, the moderator plate is used not only for shielding, moderating, and scattering neutrons, but also as a mounting base for the neutron detector 300 and the gamma detector 400 to fix these detectors.

[0073] In a specific embodiment of the present invention, the plate body of the first moderator plate 200 located at the notch of the graphite 602 is thinner than other positions to achieve moderate moderation of neutrons, that is, the neutrons after passing through the first moderator plate 200 include both fast neutrons and thermal neutrons. The first moderator plate 200 will moderate all fast neutrons, but only a portion of the fast neutrons will be moderated into thermal neutrons, and another portion of the fast neutrons will continue to maintain high energy. After such a setting, after the fast neutrons generated by the neutron source 100 pass through the first moderator plate 200, a portion of them will still maintain high energy to penetrate the material to be detected, and will be detected by the fast neutron detector 300, and the neutron penetration yield will be recorded, so as to directly determine whether there is doping inside the material; another portion of the fast neutrons will be moderated into thermal neutrons by the first moderator plate 200, and these thermal neutrons will undergo nuclear reactions with the elements in the material, releasing characteristic gamma rays, which will be detected by the gamma detector 400.

[0074] In general, the above-mentioned doping detection method adopts the new neutron activation analysis technology to realize quantitative non-destructive judgment of the doping status of the solid material to be tested. On the one hand, based on the physical quantity of neutron macroscopic cross-section, it detects the change of fast neutron penetration yield, and uses this to quickly judge whether there is a possibility of doping in the material. On the other hand, it conducts a more in-depth analysis based on the gamma energy spectrum data to obtain the type and content of elements in the material to be tested. At the same time, the detection process is fully automatic and does not require human intervention, avoiding many shortcomings of manual inspection.

[0075] The doping detection system constructed based on this doping detection method can be used Figure 8 The structure in the test can be used to detect large-volume materials with a thickness greater than 80 cm, such as pig iron, industrial briquettes, stones, etc. Fig. 9 The structure in the figure can be used to detect other materials with a thickness of less than or equal to 80 cm, such as conventional bulk materials, crushed materials, etc.

[0076] By combining neutron penetration yield monitoring with gamma spectrum judgment, it is possible to more effectively and accurately determine whether there is any adulteration in the object to be tested, as well as the type and content of material elements.

[0077] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A method for detecting doping of materials, characterized in that: include: Step S100, obtaining a first intensity of the fast neutrons before they penetrate the material to be detected and a second intensity of the fast neutrons after they penetrate the material to be detected, and also obtaining gamma spectrum data of the material to be detected; Step S200, obtaining a neutron macroscopic cross section of the material to be detected according to the first intensity and the second intensity; Step S300, judging whether there is doping based on the neutron macroscopic cross section of the material to be detected and the preset neutron macroscopic cross section of the undoped material, so as to quickly judge whether there is a possibility of doping in the material; Step S400, obtaining the type and content of elements in the material to be detected according to the gamma spectrum data of the material to be detected; Judging whether there is doping according to the neutron macroscopic cross section of the material to be detected and the preset neutron macroscopic cross section of the undoped material includes: Obtaining a neutron macroscopic cross-section difference according to the neutron macroscopic cross-section of the material to be detected and the preset neutron macroscopic cross-section of the undoped material; Determine whether the neutron macroscopic cross section difference is greater than the product of the neutron macroscopic cross section of the undoped material and the preset ratio: If yes, then there is adulteration in the material to be detected; If no, then there is no adulteration in the material to be tested; According to the gamma spectrum data of the material to be detected, the type and content of elements in the material to be detected are obtained, including: Obtaining an energy spectrum diagram according to the gamma energy spectrum data of the material to be detected; Obtaining the element category in the material to be detected according to the characteristic peaks in the energy spectrum; The energy spectrum is analyzed using the Monte Carlo library least squares method to obtain the content of each element in the material to be detected.

2. The method for detecting doping of materials according to claim 1, characterized in that: The neutron macroscopic cross section of the material to be tested is calculated according to the following formula: ， In the formula, I0 is the first intensity, I is the second intensity, is the neutron macroscopic cross section of the material to be detected, and t is the thickness of the material to be detected.

3. A system for detecting adulteration of materials, characterized in that: include: A neutron source, which is arranged on one side of the material to be detected and is used to generate fast neutrons; A first moderator plate, disposed between the neutron source and the material to be detected, for moderating the fast neutrons to obtain thermal neutrons; A neutron detector, wherein two neutron detectors are provided, one for detecting fast neutrons before penetrating the material to be detected, and the other for detecting fast neutrons after penetrating the material to be detected; A gamma detector, used to detect gamma rays generated by the reaction of the thermal neutrons with the material to be detected; a control module, configured to control the neutron source, receive detection data from the neutron detector and the gamma detector, and detect the material to be detected according to the method according to any one of claims 1 to 2; and The shielding unit is used to shield the detection area.

4. The system for detecting adulteration of materials according to claim 3, characterized in that: The control module comprises: An instruction issuing unit, used for issuing instructions to the neutron source to control the neutron source to generate fast neutrons according to the instructions; a data processing unit, configured to calculate the intensity of the fast neutrons emitted by the neutron source according to the instruction to obtain the first intensity; A first digital multi-channel plate, used for processing the received detection data of the neutron detector to obtain the second intensity; A second digital multi-channel board is used to process the received detection data of the gamma detector to obtain the gamma energy spectrum data; and The doping detection device is used to detect the material to be detected.

5. The system for detecting adulteration of materials according to claim 3, characterized in that: The system also includes a conveyor belt; The material to be detected is located on the conveyor belt; The neutron source is arranged above the material to be detected or below the conveyor belt; The neutron detector is arranged on a side of the material to be detected away from the neutron source; The gamma detector is arranged on the side and / or above the material to be detected.

6. The system for detecting adulteration of materials according to claim 5, characterized in that: The shielding unit includes a second moderator plate and graphite; The second moderation plate is arranged on both sides of the material to be detected in the conveying direction of the conveyor belt; The first moderator plate is arranged above the material to be detected, the graphite is arranged on the upper side of the first moderator plate, and a recess is provided on one side of the graphite facing the first moderator plate for installing the neutron source.

7. The system for detecting adulteration of materials according to claim 6, characterized in that: The plate body of the first moderator plate located at the graphite recess is thinner than that at other positions, so that the neutrons passing through the first moderator plate include both fast neutrons and thermal neutrons.

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