Gadolinium-doped MCP-based imaging assembly and application thereof, and thermal neutron photographing detector

Abstract

The invention provides an imaging assembly based on gadolinium-doped MCP, application thereof and a thermal neutron photographing detector, and belongs to the technical field of detectors. The gadolinium-doped MCP-based imaging assembly comprises a metal bottom plate; the lower ceramic cover plate is tightly attached to the metal bottom plate; the fluorescent screen clings to the lower ceramic cover plate and is used for de-exciting light; the fluorescent screen electrode clings to the fluorescent screen; the ceramic framework covers the lower ceramic cover plate; the MCP input electrode and the MCP output electrode are placed on the ceramic framework and are used for high-voltage power supply; the gadolinium-doped MCP is placed between the MCP input electrode and the MCP output electrode; and the upper ceramic cover plate is fixed on the ceramic framework. The large cross section of the reaction between the thermal neutrons and the gadolinium atomic nucleus is utilized, the yield of secondary particles is improved, more electrons are bombarded on the MCP, the avalanche process is triggered through electric field acceleration, the rear end is coupled with the fluorescent screen, de-excitation light is finally recorded, the thermal neutron detection efficiency is effectively improved, and the imaging time is shortened.

Description

Technical Field

[0001] The present invention relates to the field of detector technology, and in particular to an imaging component based on gadolinium-doped MCP and application of the imaging component in a thermal neutron radiography detector. Background Art

[0002] Compared with the most widely used X-ray photography, thermal neutron photography technology has very special application prospects due to the disorder and strong penetration of the cross-section of thermal neutron interaction with material atoms that changes with atomic number. It is an important supplement to X-ray photography and is widely used in the nuclear industry, aerospace, materials science, etc.

[0003] Since thermal neutrons are electrically neutral, it is difficult for them to directly make film sensitive or be recorded by detectors. It is necessary to first convert the transmitted neutrons into other secondary particles. By recording the two-dimensional spatial distribution of the secondary particles, the spatial distribution of the transmitted neutrons can be inferred to obtain information about the imaging sample.

[0004] At present, most of the more mature thermal neutron radiography detectors use LiF (ZnS) as the conversion screen. 6 Li(n,α) 3 The H reaction produces charged particles, which deposit energy and excite the luminescent material ZnS to emit light, which is eventually recorded by the photosensitive element. The thermal neutron detection efficiency is low, about 15% to 30%, and the imaging time is relatively long. Summary of the invention

[0005] In view of this, in order to solve the technical problems of low detection efficiency and long imaging time of existing thermal neutron radiographic detectors, on the one hand, the present invention provides an imaging component based on gadolinium-doped MCP, which utilizes the large cross-section of the reaction between thermal neutrons and gadolinium nuclei to increase the yield of secondary particles, bombard more electrons on the MCP, and induce an avalanche process through electric field acceleration. The rear end is coupled with a fluorescent screen so that the de-excitation luminescence is finally recorded, thereby effectively improving the thermal neutron detection efficiency and shortening the imaging time.

[0006] To achieve the above object, the present invention provides the following technical solutions: An imaging component based on gadolinium-doped MCP, comprising: Metal base plate; A lower ceramic cover plate is placed close to the metal bottom plate; A fluorescent screen, placed close to the lower ceramic cover plate, for de-excitation luminescence; A fluorescent screen electrode, arranged close to the fluorescent screen; A ceramic frame, covering the lower ceramic cover plate; MCP input electrode and MCP output electrode, placed on the ceramic skeleton and used for high voltage power supply; A gadolinium-doped MCP is placed between the MCP input electrode and the MCP output electrode; The upper ceramic cover plate is fixed on the ceramic frame.

[0007] Preferably, the upper ceramic cover plate, MCP input electrode, gadolinium-doped MCP, MCP output electrode, ceramic skeleton, phosphor screen electrode, phosphor screen, lower ceramic cover plate and metal bottom plate are coaxially arranged.

[0008] Preferably, the material of the fluorescent screen is P43 fluorescent powder.

[0009] Preferably, the upper ceramic cover plate is fixed to the ceramic frame by screws.

[0010] In a second aspect, the present invention provides the use of the above-mentioned imaging component based on gadolinium-doped MCP in a thermal neutron radiography detector.

[0011] In a third aspect, the present invention further provides a thermal neutron radiography detector, comprising the above-mentioned imaging component based on gadolinium-doped MCP.

[0012] Preferably, it also includes: Neutron entrance window; A front end cover, used for fixing the neutron incident window; The imaging assembly based on gadolinium-doped MCP is placed close to the neutron incident window; An MCP fixing plate, fixed on the front end cover and used to fix the metal bottom plate; A high vacuum connector, connected to the surface of the MCP fixing plate, for supplying power to the imaging assembly based on the gadolinium-doped MCP; A vacuum chamber, fixed at the rear end of the MCP fixing plate; A rear end cover, fixed to the rear side of the vacuum chamber; A reflector support plate, fixed on the rear end cover and extending into the vacuum chamber; A reflector fixing plate, fixed on the reflector support plate and located at the center of the vacuum chamber; A reflector, fixed on the reflector fixing plate and deflected at a first angle with respect to the axial direction of the vacuum chamber; A light beam receiving port is fixed on the vacuum chamber and is perpendicular to the axis of the vacuum chamber and deflected at a second angle to the reflector surface; A lens intermediate pipe, fixed on the beam pipe; An optical lens group, arranged inside the tube cavity of the lens for focusing light; A camera transition bracket, fixed behind the connecting pipe in the lens and used to fix the camera; CCD camera, used to record the two-dimensional spatial distribution of photons; A molecular pump bundle tube is fixed at the lower end interface of the vacuum chamber and is used for connecting to a vacuum system; Support plate, used to fix the whole set of detectors on a flat surface.

[0013] Preferably, the first angle is 45°.

[0014] Preferably, the second angle is 45°.

[0015] Preferably, the invention further comprises a bracket for moving the thermal neutron radiography detector and supporting the support plate.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The imaging component based on gadolinium-doped MCP provided by the present invention utilizes the large cross section of the reaction between thermal neutrons and gadolinium nuclei to increase the yield of secondary particles, bombard more electrons on the MCP, and induce an avalanche process through electric field acceleration. The rear end is coupled with a fluorescent screen so that its deexcitation light is finally recorded, effectively improving the efficiency of thermal neutron detection and shortening the imaging time. When the transmitted neutrons are incident on the imaging component based on the gadolinium-doped MCP through the neutron incident window, the thermal neutrons react with the gadolinium nuclei. 155 Gd(n,γ) 156 Gd, 157 Gd(n,γ) 158 The secondary photons generated by the Gd reaction hit the MCP and knock out more electrons, which are accelerated by the electric field and trigger the avalanche process. They hit the fluorescent screen at the rear end of the MCP and deposit energy. The particles in the screen de-excite and emit light, which is transmitted along the vacuum cavity, reflected by the mirror at 90°, focused by the optical lens group, and recorded by the CCD camera. Due to the coupling of metal gadolinium doping and MCP, the efficiency of thermal neutron detection is improved, the imaging time is shortened, the dark noise is reduced, and the signal-to-noise ratio is increased, as follows: Improving thermal neutron detection efficiency Large cross-section reaction: Metallic gadolinium has a large neutron absorption cross-section, which can effectively capture thermal neutrons and increase the yield of secondary particles.

[0017] More electrons: Secondary photons bombard the MCP, generating more electrons and improving detection efficiency.

[0018] Shorten imaging time Fast response: Due to the increased secondary particle yield, the imaging component can respond to thermal neutrons more quickly, shortening the imaging time.

[0019] Efficient transmission: Efficient transmission and recording of deexcitation light further improves imaging speed.

[0020] Dark noise reduction Reduce background interference: The high sensitivity of gadolinium-doped MCP reduces the interference of background noise and improves the signal-to-noise ratio of imaging.

[0021] Low dark current: The optimized design of MCP reduces dark current and further reduces dark noise.

[0022] Increased signal-to-noise ratio High sensitivity: The high sensitivity of gadolinium-doped MCP improves signal strength and increases the signal-to-noise ratio.

[0023] Optimized design: The optimized design of MCP and phosphor screen further improves the signal-to-noise ratio and enhances the imaging quality.

[0024] Stability and reliability Stable performance: The stable performance of gadolinium-doped MCP ensures reliability and consistency in long-term use.

[0025] Radiation resistance: MCP's radiation resistance enables it to work stably in high radiation environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the structure of the imaging component based on gadolinium-doped MCP; Figure 2 A schematic diagram of the explosion structure of an imaging component based on gadolinium-doped MCP; Figure 3 This is a schematic diagram of the structure of a thermal neutron radiography detector; Figure 4 This is a schematic diagram of the explosion structure of the thermal neutron camera detector; In the figure, 1. screw; 2. MCP input electrode; 3. MCP output electrode; 4. fluorescent screen electrode; 5. upper ceramic cover; 6. metal bottom plate; 7. gadolinium-doped MCP; 8. ceramic frame; 9. fluorescent screen; 10. lower ceramic cover; 11. neutron incident window; 12. front cover; 13. MCP fixing plate; 14. high vacuum connector; 15. vacuum chamber; 16. rear cover; 17. beam pipe; 18. lens middle pipe; 19. camera transition bracket; 20. CCD camera; 21. molecular pump beam tube; 22. support plate; 23. bracket; 24. reflector; 25. reflector fixing plate; 26. reflector support plate; 27. optical lens group. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention; it is obvious that the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments, and all other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making creative work are within the scope of protection of the present invention.

[0028] In the description of the present invention, it should be noted that the terms "upper", "lower", "inside", "outside", "top / bottom" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0029] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "provided with", "mounted / connected", "connected", etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0030] like Figure 1-4 As shown, the present invention provides an imaging component based on gadolinium-doped MCP7, wherein MCP refers to a microchannel plate, which is a high-sensitivity detection device for electron multiplication, and its core function is to amplify weak signals through the electron avalanche effect. The present invention includes: Metal base plate 6; The lower ceramic cover plate 10 is placed close to the metal bottom plate 6; The fluorescent screen 9 is placed close to the lower ceramic cover plate 10 and is used for de-excitation luminescence, and its material is preferably P43 fluorescent powder; The phosphor screen electrode 4 is arranged close to the phosphor screen 9; A ceramic frame 8, covering the lower ceramic cover plate 10; MCP input electrode 2 and MCP output electrode 3, placed on the ceramic skeleton 8 and used for high voltage power supply; Gadolinium-doped MCP 7, placed between the MCP input electrode 2 and the MCP output electrode 3; The upper ceramic cover plate 5 is fixed on the ceramic frame 8 , preferably by screws 1 .

[0031] In the present invention, the upper ceramic cover plate 5, the MCP input electrode 2, the gadolinium-doped MCP 7, the MCP output electrode 3, the ceramic skeleton 8, the phosphor screen electrode 4, the phosphor screen 9, the lower ceramic cover plate 10 and the metal base plate 6 are coaxially arranged. The coaxial arrangement ensures the precise alignment between the components, reduces the signal loss and improves the detection efficiency. The coaxial arrangement makes the distribution of secondary particles and electrons in the MCP more uniform, and improves the stability and consistency of the signal. The coaxial arrangement ensures the linearity of the signal transmission path and improves the resolution of the imaging. The coaxial arrangement makes the distribution of the optical signal on the phosphor screen 9 more uniform, and improves the quality of the imaging.

[0032] The working principle of the above-mentioned imaging component based on gadolinium-doped MCP7 provided by the present invention is as follows: because 155 Gd and 157 Gd has a large interaction cross section with thermal neutrons. When transmitted thermal neutrons bombard gadolinium-doped MCP7, they mainly interact with gadolinium nuclei. 155 Gd(n,γ) 156 Gd, 157 Gd(n,γ) 158 The secondary photons generated by the Gd reaction hit the wall of the microchannel and bombard more electrons, which are accelerated by the electric field to trigger an avalanche process, emitted along the axial direction of the microchannel, hit the fluorescent screen 9 close to the rear end of the gadolinium-doped MCP7 and deposit energy, and the particles in the P43 phosphor de-excite to emit light, which is transmitted along the vacuum cavity 15. That is, the large cross-section of the reaction between thermal neutrons and gadolinium nuclei is used to increase the yield of secondary particles, bombard more electrons on the MCP, and trigger an avalanche process through electric field acceleration. The rear end is coupled with the fluorescent screen 9, so that the de-excited light is finally recorded, effectively improving the efficiency of thermal neutron detection and shortening the imaging time.

[0033] In summary, due to the coupling of metal gadolinium doping and MCP in the present invention, the thermal neutron detection efficiency is improved, the imaging time is shortened, the dark noise is reduced, and the signal-to-noise ratio is increased.

[0034] In a second aspect, the present invention provides the use of the above-mentioned imaging component based on gadolinium-doped MCP7 in a thermal neutron radiography detector.

[0035] In a third aspect, the present invention further provides a thermal neutron radiography detector, comprising the above-mentioned imaging component based on gadolinium-doped MCP7.

[0036] The present invention also includes: Neutron incident window 11; A front end cover 12, used for fixing the neutron incident window 11; The imaging component based on gadolinium-doped MCP7 is placed close to the neutron incident window 11; An MCP fixing plate 13, fixed on the front end cover 12 and used to fix the metal base plate 6 (based on the metal base plate 6 in the gadolinium-doped MCP7 imaging assembly); A high vacuum connector 14, connected to the surface of the MCP fixing plate 13, for supplying power to the imaging assembly based on the gadolinium-doped MCP7, and the number of the high vacuum connector 14 is preferably 3; A vacuum chamber 15, fixed at the rear end of the MCP fixing plate 13; A rear end cover 16 is fixed to the rear side of the vacuum chamber 15; A reflector support plate 26 is fixed on the rear end cover 16 and extends into the vacuum chamber 15; A reflector fixing plate 25, fixed on the reflector support plate 26 and located at the center of the vacuum chamber 15; A reflector 24 is fixed on the reflector fixing plate 25 and is deflected at a first angle with the axial direction of the vacuum chamber 15, wherein the first angle is preferably 45°; The light beam pipe 17 is fixed on the vacuum chamber 15 and is perpendicular to the axis of the vacuum chamber 15 and is deflected at a second angle with the surface of the reflector 24, wherein the second angle is preferably 45°; A lens middle pipe 18, fixed on the beam pipe 17; An optical lens group 27, arranged inside the cavity of the lens tube 18, for focusing light; A camera transition bracket 19, fixed behind the tube 18 in the lens and used to fix the camera; CCD camera 20, used to record the two-dimensional spatial distribution of photons; The molecular pump bundle tube 21 is fixed at the lower end interface of the vacuum chamber 15 for connecting to the vacuum system; The support plate 22 is used to fix the entire set of detectors on a plane.

[0037] In the present invention, a bracket 23 is also included to facilitate the movement of the entire set of detectors and to support the support plate 22 .

[0038] In the thermal neutron radiographic detector provided by the present invention, the mirror surface direction of the reflector 24 is fixed at a 45° deflection with the axial direction of the vacuum chamber 15, so as to deflect the light beam by 90°, so as to protect the CCD camera 20 from direct irradiation by the transmitted neutron beam, so as to avoid damaging the internal components. When the transmitted thermal neutrons bombard the imaging assembly based on the gadolinium-doped MCP7, the light beam emitted from the fluorescent screen 9 propagates along the vacuum chamber 15, is reflected by the reflector 24, and the light beam is deflected by 90°, transmitted along the axial direction of the beam tube 17, focused by the optical lens group, and finally recorded on the CCD camera 20. The two-dimensional distribution information of the transmitted neutrons is inferred from the obtained two-dimensional spatial distribution of photons, and then the sample information is obtained.

[0039] In the thermal neutron radiographic detector provided by the present invention, the neutron incident window 11, the front cover 12, the imaging component based on the gadolinium-doped MCP7, the MCP fixing plate 13, the vacuum chamber 15, and the rear cover 16 are coaxially arranged, and the beam pipe 17, the lens pipe 18, the camera transition bracket 19, and the CCD camera 20 are coaxially arranged. The whole set of detectors is compact and reliable in design, with short imaging time and high imaging quality. The details are as follows: Improve detection efficiency Alignment Accuracy: The coaxial setup ensures precise alignment between components, reducing signal loss and improving detection efficiency.

[0040] Uniform distribution: The coaxial setting makes the distribution of secondary particles and electrons in the MCP more uniform, improving the stability and consistency of the signal.

[0041] Reduce background noise Reduced Interference: The coaxial setup reduces external interference and improves the signal-to-noise ratio.

[0042] Shielding effect: The front cover 12 and the rear cover 16 provide good shielding effect, further reducing background noise.

[0043] Improve image quality Resolution: The coaxial setting ensures the linearity of the signal transmission path and improves the resolution of the imaging.

[0044] Uniformity: The coaxial setting makes the light signal distribution on the fluorescent screen more uniform, improving the imaging quality.

[0045] Stability and reliability Stable structure: The coaxial setting provides better structural stability and reduces displacement caused by vibration or external forces.

[0046] Durability: The MCP fixing plate 13 and the vacuum chamber 15 provide good mechanical support, thus extending the service life of the equipment.

[0047] Simplified assembly and maintenance Simplified assembly: The coaxial setting simplifies the assembly process, reduces assembly errors and improves production efficiency.

[0048] Easy maintenance: The coaxial setting makes it easy to disassemble and replace each component, which facilitates maintenance and repair.

[0049] Optimizing the electric field distribution Uniform electric field: The coaxial setup makes the electric field distribution more uniform, improving the efficiency of electron acceleration and avalanche process.

[0050] Reduce edge effects: The coaxial setting reduces edge effects, avoids uneven distribution of the electric field, and improves signal stability and reliability.

[0051] Optimizing the optical path Straight-line transmission: The coaxial setting ensures straight-line transmission of optical signals, reduces reflection and scattering in the optical path, and improves imaging quality.

[0052] Focusing effect: The coaxial arrangement of the lens group and the CCD camera 20 ensures the precise focusing of the optical signal and improves the clarity of the imaging.

[0053] The above are only preferred specific implementations of the present invention; however, the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solutions and improved concepts of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. An imaging component based on gadolinium-doped MCP, characterized in that: include: Metal base plate; A lower ceramic cover plate is placed close to the metal bottom plate; A fluorescent screen, placed close to the lower ceramic cover plate, for de-excitation luminescence; A fluorescent screen electrode, arranged close to the fluorescent screen; A ceramic frame, covering the lower ceramic cover plate; MCP input electrode and MCP output electrode, placed on the ceramic skeleton and used for high voltage power supply; A gadolinium-doped MCP is placed between the MCP input electrode and the MCP output electrode; The upper ceramic cover plate is fixed on the ceramic frame.

2. The imaging component based on gadolinium-doped MCP according to claim 1, characterized in that: The upper ceramic cover plate, MCP input electrode, gadolinium-doped MCP, MCP output electrode, ceramic skeleton, fluorescent screen electrode, fluorescent screen, lower ceramic cover plate and metal bottom plate are coaxially arranged.

3. The imaging component based on gadolinium-doped MCP according to claim 1, characterized in that: The material of the fluorescent screen is P43 fluorescent powder.

4. An imaging component based on gadolinium-doped MCP according to any one of claims 1 to 3, characterized in that: The upper ceramic cover plate is fixed on the ceramic frame by screws.

5. Use of an imaging component based on gadolinium-doped MCP according to any one of claims 1 to 4 in a thermal neutron radiography detector.

6. A thermal neutron radiography detector, characterized in that: An imaging component based on gadolinium-doped MCP comprising any one of claims 1-4.

7. A thermal neutron radiography detector according to claim 6, characterized in that: Also includes: Neutron entrance window; A front end cover, used for fixing the neutron incident window; An imaging component based on a gadolinium-doped MCP according to any one of claims 1 to 4, placed close to the neutron incident window; An MCP fixing plate, fixed on the front end cover and used to fix the metal bottom plate; A high vacuum connector connected to the surface of the MCP fixing plate, used to power an imaging component based on a gadolinium-doped MCP according to any one of claims 1 to 4; A vacuum chamber, fixed at the rear end of the MCP fixing plate; A rear end cover, fixed to the rear side of the vacuum chamber; A reflector support plate, fixed on the rear end cover and extending into the vacuum chamber; A reflector fixing plate, fixed on the reflector support plate and located at the center of the vacuum chamber; A reflector, fixed on the reflector fixing plate and deflected at a first angle with respect to the axial direction of the vacuum chamber; A light beam receiving port is fixed on the vacuum chamber and is perpendicular to the axis of the vacuum chamber and deflected at a second angle to the reflector surface; A lens intermediate pipe, fixed on the beam pipe; An optical lens group, arranged inside the tube cavity of the lens for focusing light; A camera transition bracket, fixed behind the connecting pipe in the lens and used to fix the camera; CCD camera, used to record the two-dimensional spatial distribution of photons; A molecular pump bundle tube is fixed at the lower end interface of the vacuum chamber and is used for connecting to a vacuum system; Support plate, used to fix the whole set of detectors on a flat surface.

8. A thermal neutron radiography detector according to claim 7, characterized in that: The first angle is 45°.

9. The thermal neutron radiography detector according to claim 7, characterized in that: The second angle is 45°.

10. A thermal neutron radiography detector according to any one of claims 7 to 9, characterized in that: The invention also comprises a bracket for moving the thermal neutron radiography detector and supporting the support plate.

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