High-temperature-resistant photoelectric conversion assembly for radiation detector, preparation method of high-temperature-resistant photoelectric conversion assembly and radiation detector

Abstract

The invention provides a high-temperature-resistant photoelectric conversion assembly for a radiation detector. The high-temperature-resistant photoelectric conversion assembly comprises a substrate layer, a protective layer and a cathode layer, the substrate layer is a lead fluoride crystal, the lead fluoride crystal is provided with a first surface and a second surface which are oppositely arranged, the first surface is configured as a growth surface, and the growth surface comprises a photocathode surface and indium covers arranged on the two sides of the photocathode surface respectively; the protective layer comprises a magnesium fluoride film and an aluminum oxide film which are sequentially laminated on the growth surface in a direction far away from the growth surface; and the cathode layer is an alkali metal layer which is laminated on an aluminum oxide film which is far away from the magnesium fluoride film and is arranged corresponding to the photocathode surface. Magnesium fluoride is used as an intermediate transition film layer, a PbF2-MgF2-Al2O3 protective film layer is formed, the lead fluoride crystal is prevented from reacting with alkali metal, meanwhile, the incident light transmittance of the lead fluoride crystal is improved, and therefore the quantum efficiency of the whole tube is improved.

Description

Technical Field

[0001] This invention relates to the field of photoelectric detection technology, and more specifically to a high-temperature resistant photoelectric conversion component for a radiation detector, its preparation method, and the radiation detector itself. Background Technology

[0002] A radiation detector is a specialized device that converts the energy or presence information of radiation (mainly ionizing radiation, such as alpha rays, beta rays, gamma rays, X-rays, neutrons, etc.) into measurable and recordable physical signals (such as electrical signals and optical signals). Its core function is to sense, identify, and quantify radiation, and it is widely used in nuclear science, medicine, industry, environmental protection, security, and other fields. The core units of a radiation detector include a signal conversion unit, a signal processing unit, and a signal receiving unit. When the detector is working, incident light shines on the signal conversion unit, where it is converted into electrons through photoelectric conversion. These electrons are then multiplied by the signal processing unit to form an electrical signal, which is then received by the signal receiving unit to output a current signal.

[0003] Typically, radiation detectors require an additional scintillator layer to convert incident radiation into optical signals for reception. Lead fluoride crystals, however, can function as scintillators themselves; when radiation (such as gamma rays, beta rays, and high-energy protons) passes through them, it is partially converted into photons. Detectors using lead fluoride crystals as optical windows combine luminescence (scintillator function) and detection capabilities, optimizing both light transmission and detection performance while shortening the time from radiation interaction with the reaction medium to photon generation, effectively improving detector efficiency.

[0004] In the medical field, the core objective of time-of-flight positron emission tomography (TOF-PET) is to achieve extremely precise measurement of the time difference between the arrival of two annihilated gamma photons at the detector. This parameter typically needs to reach the order of hundreds of picoseconds (ps) or even tens of picoseconds, which is also a key prerequisite for determining the spatial resolution and lesion detection efficiency of TOF-PET imaging.

[0005] To achieve such stringent time measurement accuracy, the primary condition is to capture a sufficient number of photons to generate an electrical signal with high intensity and a steep rise edge. In TOF-PET, gamma photons are first converted into visible light photons by a scintillator. Only by collecting enough of these visible light photons can the subsequent photoelectric conversion stage output an electrical signal with "high signal amplitude and clear start edge". This type of signal can significantly reduce the uncertainty in the time discrimination process.

[0006] Therefore, the system is more suitable for using large-size microchannel plate photomultiplier tubes (MCP-PMTs), whose significant advantage lies in the larger detection area, which can effectively cover the light output area of ​​the scintillator and maximize the collection of visible light photons emitted from the scintillator (avoiding photon loss due to insufficient detection area). Sufficient photon input provides an ideal electrical signal with "high signal-to-noise ratio and clear steep-edge characteristics" for time discrimination technologies such as Leading Edge Discrimination (LED), enabling more precise locking of the starting moment of the electrical signal (i.e., the time point when the gamma photon arrives at the detector). This directly promotes the improvement of the time resolution of the TOF-PET system, providing core technical support for subsequent precise positioning of tracer distribution and optimization of imaging contrast.

[0007] However, lead fluoride crystals face significant application bottlenecks: their high lead content makes them prone to reacting with alkali metals used as cathode materials at high temperatures, forming oily black lead reducing agents. These reactants significantly reduce the crystal's light transmittance (hindering scintillation photon transmission) and contaminate the indium sealing interface, leading to seal failure and leakage. Therefore, a protective layer is required between the lead fluoride and the alkali metal. Currently, the mainstream protective layer materials are Al2O3 and SiO2, but lead fluoride crystals have a much higher coefficient of thermal expansion, 4-5 times that of Al2O3 and SiO2. Furthermore, the larger the crystal size, the more significant the difference in deformation between the protective layer and the crystal during high-temperature vapor deposition. When cooling after vapor deposition and during subsequent use, the difference in shrinkage between the two materials can cause the protective layer to fail, peeling off or lifting, ultimately failing to protect the lead fluoride crystal substrate. Summary of the Invention

[0008] The purpose of this invention is to address the shortcomings of existing technologies by providing a high-temperature resistant photoelectric conversion component for radiation detectors. By setting magnesium fluoride as an intermediate transition film layer, a PbF2-MgF2-Al2O3 protective film layer is formed to prevent lead fluoride crystals from reacting with alkali metals, while simultaneously increasing the incident light transmittance of lead fluoride crystals, thereby improving the overall quantum efficiency of the tube.

[0009] According to a first aspect of the present invention, a high-temperature resistant photoelectric conversion component for a radiation detector is provided, comprising a substrate layer, a protective layer, and a cathode layer; The substrate layer is a lead fluoride crystal, which has a first surface and a second surface disposed opposite to each other, and the first surface is configured as a growth surface, which includes a photocathode surface and indium covers disposed on both sides of the photocathode surface. The protective layer consists of a magnesium fluoride film and an aluminum oxide film sequentially stacked on the growth surface along a direction away from the growth surface. The cathode layer is an alkali metal layer stacked on an alumina film that is far from the magnesium fluoride film and corresponds to the photocathode surface.

[0010] As an optional implementation, the thickness ratio of the magnesium fluoride film and the aluminum oxide film is 1:(2~3).

[0011] As an optional implementation, the thickness of the magnesium fluoride film is 30 nm to 50 nm.

[0012] As an optional implementation, the thickness of the alumina film is 80 nm to 120 nm.

[0013] As an optional implementation, the alkali metal in the alkali metal layer is K-Cs-Sb.

[0014] As an optional implementation, a NiCr film, a Cu film, and an Ag film are stacked on the protective layer of the indium cover.

[0015] According to a second aspect of the present invention, a method for fabricating the aforementioned high-temperature resistant photoelectric conversion component for a radiation detector is provided, comprising: Magnesium fluoride thin film and aluminum oxide thin film are sequentially deposited on the growth surface of lead fluoride crystal. Subsequently, NiCr film, Cu film and Ag film were sequentially deposited on the alumina film covered by indium. Finally, an alkali metal layer is deposited on the alumina film on the photocathode surface.

[0016] As an optional implementation, the method for preparing a high-temperature resistant photoelectric conversion component for a radiation detector according to claim 7 is characterized in that the specific process of depositing a magnesium fluoride thin film on the growth surface of the lead fluoride crystal includes: Magnesium fluoride and titanium tetrafluoride were used as reaction sources, and a magnesium fluoride thin film was deposited on the growth surface of lead fluoride crystals by atomic deposition at a temperature of 160 ℃ to 200 ℃.

[0017] As an optional implementation, the specific process of depositing an aluminum oxide film on a magnesium fluoride film includes: Using trimethylaluminum and water as the reaction source, magnesium fluoride films were deposited on magnesium fluoride films by atomic deposition at a temperature of 160 ℃ to 200 ℃.

[0018] According to a third aspect of the present invention, a radiation detector is provided, characterized in that the photoelectric conversion component of the radiation detector is the aforementioned high-temperature resistant photoelectric conversion component for radiation detectors, or a high-temperature resistant photoelectric conversion component prepared by the aforementioned method.

[0019] As can be seen from the above technical solutions of the present invention, the high-temperature resistant photoelectric conversion component for radiation detectors proposed in this invention has the following advantages: 1. A gradient distribution of coefficient of thermal expansion (CET) is constructed through a magnesium fluoride transition film layer. The CET is distributed in an orderly manner from "high to medium to low". The single CET abrupt change between PbF2 and Al2O3 without the transition layer is transformed into two gradual CET changes between PbF2-MgF2 and MgF2-Al2O3. This allows the thermal deformation of each layer to be coordinated step by step when the temperature changes. The thermal stress that was originally concentrated on a single interface is dispersed to two interfaces and significantly reduced. At the same time, the chemical inertness and coating compatibility of MgF2 ensure that there is no chemical reaction at the interface and that the bonding is tight. Ultimately, the cracking, peeling or warping of the film layer is avoided, and the PbF2-MgF2-Al2O3 protective film layer is flat and firm. 2. High-efficiency anti-reflection of lead fluoride crystals is achieved by constructing a MgF2-Al2O3 double film. The continuous refractive index gradient formed by magnesium fluoride (between air and alumina) and alumina (between magnesium fluoride and lead fluoride) is utilized. Combined with the interference cancellation effect generated by precise control of film thickness, the light reflection loss is greatly reduced, and the incident light transmittance reaches up to 92%. The high transmittance design proposed in this invention provides stable and sufficient incident light for cathode fabrication, ensuring accurate and reliable photocurrent signals, thereby precisely controlling the alkaline source output to obtain a suitable K-Cs-Sb ratio. On the other hand, it increases the amount of light incident to the cathode, and with the optimized cathode material, significantly improves the quantum efficiency of the entire tube in converting photons into photoelectrons, forming a synergistic effect of enhanced transmittance, quality control, and improved efficiency. 3. By constructing a gradient of thermal expansion coefficients through a magnesium fluoride transition film layer, the expansion coefficients between Al2O3 and Ag films are matched, achieving a sealed combination between the optical window and the indium sealing tank. This enables long-term stable indium sealing of the optical window assembly under high temperature and high radiation environments, providing process and performance assurance for the practical application of lead fluoride crystal optical windows. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the high-temperature resistant photoelectric conversion component for radiation detectors according to the present invention.

[0021] Figure 2 This is a schematic diagram of the structure of the radiation detector of the present invention.

[0022] Figure 3 This is a physical image of the lead fluoride crystal substrate used in the example of this invention.

[0023] Figure 4 This is a physical image of a radiation detector assembled using the photoelectric conversion components of an embodiment of the present invention.

[0024] Figure 5This describes the surface state of the light window in Embodiment 1 of the present invention; wherein, Figure 5 Part A in the diagram is a surface test image; Figure 5 Part B in the figure is a statistical chart of surface flatness.

[0025] Figure 6 This is the surface state of the light window in Comparative Example 1 of the present invention; wherein, Figure 6 Part A in the diagram is a surface test image; Figure 6 Part B in the figure is a statistical chart of surface flatness. Detailed Implementation

[0026] To better understand the technical content of the present invention, specific embodiments are described below in conjunction with the accompanying drawings.

[0027] Various aspects of the invention are described in this disclosure with reference to the accompanying drawings, in which numerous illustrative embodiments are shown. The embodiments of this disclosure are not necessarily intended to encompass all aspects of the invention. It should be understood that the various concepts and embodiments described above, as well as those described below in more detail, can be implemented in any of a number of ways.

[0028] Although large-size lead fluoride crystals (with a relatively long side dimension > 20 mm) exhibit significant advantages as optical windows in long-term radiation monitoring scenarios under special environments such as high temperature (<300 ℃) and high radiation (such as high density and excellent radiation detection response characteristics), core issues such as the thermal expansion matching between the lead fluoride crystal and the protective layer and the stability of the interface bonding are significantly amplified as the crystal size increases, ultimately making it difficult for this technical solution to achieve industrialization and practical application.

[0029] To address the practical limitations of large-size lead fluoride crystal optical windows, this invention designs a high-temperature resistant photoelectric conversion component for radiation detectors. By using magnesium fluoride as an intermediate transition film, a PbF2-MgF2-Al2O3 protective film is formed to prevent the lead fluoride crystal from reacting with alkali metals. This design utilizes the magnesium fluoride transition film to create a gradient design of the coefficient of thermal expansion (CET), achieving thermal stress dispersion and reduction, preventing film cracking, peeling, or warping. Simultaneously, it improves the incident light transmittance of the lead fluoride crystal, enhances the overall quantum efficiency, and ensures the long-term stability of the optical window component under high-temperature and high-radiation environments. High-Temperature Resistant Photoelectric Conversion Components for Radiation Detectors

[0030] Combination Figures 1-2 As shown, the exemplary high-temperature resistant photoelectric conversion component for a radiation detector of the present invention includes a substrate layer 10, a protective layer 20, and a cathode layer 30.

[0031] The substrate 10 is a lead fluoride crystal, which has a first surface and a second surface disposed opposite to each other, and the first surface is configured as a growth surface, which includes a photocathode surface 11 and indium cover surfaces 12 disposed on both sides of the photocathode surface.

[0032] The protective layer 20 consists of a magnesium fluoride film 21 and an aluminum oxide film 22 sequentially stacked on the growth surface in a direction away from the growth surface.

[0033] The cathode layer 30 is an alkali metal layer stacked on an alumina film that is far away from the magnesium fluoride film and is disposed on the photocathode surface.

[0034] In some embodiments, the thickness ratio of the magnesium fluoride film 21 to the aluminum oxide film 22 is 1:(2~3).

[0035] In some embodiments, the thickness of the magnesium fluoride film is 30 nm to 50 nm.

[0036] In some embodiments, the thickness of the alumina film is 80 nm to 120 nm.

[0037] In some embodiments, the alkali metal in the alkali metal layer is K-Cs-Sb.

[0038] In some embodiments, a NiCr film 121, a Cu film 122, and an Ag film 123 are stacked on the protective layer of the indium cover; wherein, the NiCr film 121 is a conductive layer, and the Cu film 122 and the Ag film 123 are indium sealing film layers 12A. The function of the indium sealing film layers is to be bonded to the indium sealing groove 104A on the outer casing component by means of hot-pressing indium sealing at high temperature, so as to seal the device.

[0039] In other embodiments, the growth surface further includes a connection surface 13 between the photocathode surface 11 and the indium cover 12, the indium cover 12 and the connection surface 13 constituting an indium sealing region; a magnesium fluoride film 21, an aluminum oxide film 22 and a NiCr film 121 are sequentially disposed on the connection surface; wherein, the magnesium fluoride film 21 and the aluminum oxide film 22 are still protective film layers, and the NiCr film 121 serves as a conductive layer connecting the indium sealing layer and the alkali metal layer, so that the voltage can be applied to the photocathode film layer by applying voltage to the indium sealing layer during operation.

[0040] If an indium sealing layer is deposited on the connection surface 13, the liquid indium tin alloy is likely to flow into the housing assembly during indium sealing, thus causing a short circuit. Therefore, only nickel-chromium alloy is deposited on the connection surface 13. Fabrication method of high-temperature resistant photoelectric conversion component for radiation detector

[0041] In another exemplary embodiment of the present invention, a method for fabricating the aforementioned high-temperature resistant photoelectric conversion component for a radiation detector is provided, comprising: Magnesium fluoride thin film and aluminum oxide thin film are sequentially deposited on the growth surface of lead fluoride crystal. Subsequently, NiCr films were deposited on the alumina films of the indium cover and the bonding surface, and then Cu and Ag films were deposited sequentially on the NiCr films of the indium cover. Finally, an alkali metal layer is deposited on the alumina film on the photocathode surface.

[0042] In some embodiments, a magnesium fluoride thin film and an aluminum oxide thin film are sequentially deposited on the growth surface of the lead fluoride crystal. The specific process includes: Magnesium fluoride and titanium tetrafluoride were used as reaction sources, and a magnesium fluoride thin film was deposited on the growth surface of lead fluoride crystals by atomic deposition at a temperature of 160 ℃~200 ℃. Subsequently, using trimethylaluminum and water as the reaction source, a magnesium fluoride film was deposited on the magnesium fluoride film using atomic deposition technology at a temperature of 160 ℃ to 200 ℃.

[0043] In some embodiments, an alkali metal layer is deposited on the alumina film on the photocathode surface by vapor deposition, specifically including: In a vacuum environment, by controlling the evaporation rates of the K source, Sb source, and Cs source sequentially, bottom K evaporation, K-Sb co-evaporation, and K-Cs-Sb co-evaporation are performed to deposit an alkali metal layer on the alumina film on the photocathode surface.

[0044] In some embodiments, a NiCr film is deposited on the alumina film of the indium cover and the bonding surface, and then a Cu film and an Ag film are sequentially deposited on the NiCr film of the indium cover. The specific process includes: NiCr films were deposited on the aluminum oxide films on the indium surface and the bonding surface by electron beam evaporation of a pure nickel-chromium source at a vacuum degree of 2E-3Pa and a temperature of 200 ℃~220 ℃. Subsequently, a Cu thin film was deposited on the NiCr thin film covered with indium by electron beam evaporation at a vacuum degree of 2E-3Pa and a temperature of 260 ℃~280 ℃. Finally, under a vacuum of 2E-3Pa and at room temperature, an Ag film was deposited on the Cu film by electron beam evaporation of a pure silver source.

[0045] It is understandable that evaporating alkali metal layers and evaporating NiCr, Cu, and Ag films are existing technologies, and those skilled in the art can perform evaporation treatments according to existing processes. Radiation detector

[0046] In another exemplary embodiment of the present invention, a radiation detector is also provided, wherein the photoelectric conversion component of the radiation detector is the aforementioned high-temperature resistant photoelectric conversion component.

[0047] In one example, such as Figure 2 As shown, the radiation detector includes a photoelectric conversion component 101, an electron multiplier component 102, an electron receiving component 103, and a housing 104.

[0048] The electron multiplier 102 is disposed between the photoelectric conversion component 101 and the electron receiving component 103 along the transmission path of the radiation signal.

[0049] The photoelectric conversion component 101 and the electron receiving component 103 are respectively sealed and connected to the outer shell 104, and the three together form a sealed cavity for accommodating the electron multiplier component.

[0050] In some alternative examples, the electron multiplier 102 is at least two microchannel plates 102A; the electron receiver 103 is a single metal surface or an array of multiple metal surfaces, the metal surfaces leading out electrodes through pins and connected to a signal receiver, wherein the multiple metal surfaces are insulated from each other.

[0051] It is understood that the structure of the radiation detector is prior art, for example, Chinese patent document with publication number CN116705586A, and the structure of the radiation detector includes, but is not limited to, the structure described above.

[0052] To facilitate better understanding, the present invention will be further illustrated below with several specific examples, but the preparation process is not limited to these examples, and the content of the present invention is not limited to these examples.

[0053] Unless otherwise specified, the materials in the examples are prepared according to existing methods or purchased directly from the market.

[0054] The structure of the radiation detector is the same as that in Chinese patent document CN116705586A. Example 1

[0055] [Preparation of photoelectric conversion components]

[0056] (1) The lead fluoride crystals were purchased from an external supplier (Shanghai Institute of Ceramics, lead fluoride content ≥99.9%; dimensions: 51 mm × 51 mm × 5.5 mm, connection surface height 2.5 mm, such as...). Figure 3 As shown), the peak transmittance after surface treatment is 85% (surface treatment method: polishing, using aluminum oxide polishing powder, water polishing liquid, 1.5 μm, 1 μm, 0.5 μm, a step polishing method from coarse to fine), with the grooved side as the growth surface of the film layer.

[0057] (2) The treated lead fluoride crystals are placed in an ALD coating equipment. First, a magnesium fluoride film is deposited. The reaction source is selected as magnesia and titanium tetrafluoride. The designed coating thickness is 50 nm. The program has a single cycle thickness of about 0.1 nm, a cycle number of 500, a reaction temperature of 200 ℃, and a vacuum degree of 1~5 Pa. The magnesium fluoride film covers the entire growth surface of lead fluoride.

[0058] (3) Place the lead fluoride crystal with the magnesium fluoride film on it in the ALD coating equipment and evaporate the aluminum oxide protective film. The reaction source is trimethylaluminum and water. The designed coating thickness is 120 nm. The program is to evaporate the thickness of about 0.1 nm per cycle, and the number of cycles is 1200. The reaction temperature is set to 200 ℃ and the vacuum degree is 1~5 Pa. The aluminum oxide protective film covers the entire magnesium fluoride film.

[0059] (4) Use a fixture to shield the photocathode surface and deposit a nickel-chromium alloy film on the indium-sealed area of ​​the lead fluoride crystal (indium cover and connecting surface). Set the film deposition reaction temperature to 200 ℃, the film thickness to 150 nm, the vacuum degree to 2E-3 Pa, and use electron beam evaporation of pure nickel-chromium source (99.99%) for film deposition. The deposition rate is 0.1 nm / s.

[0060] (5) A fixture is required to shield the photocathode surface and the connection surface. A copper film layer is deposited on the indium surface. The reaction temperature is set to 280 °C, the film thickness is set to 250 nm, the vacuum degree is 2E-3 Pa, and the film is deposited by electron beam evaporation of pure copper source (99.99%). The evaporation rate is 0.5 nm / s.

[0061] (6) A silver film layer is deposited on the copper film layer. The reaction temperature is set to room temperature, the film thickness is set to 100 nm, the vacuum degree is 2E-3Pa, and the film is deposited by electron beam evaporation of pure silver source (99.99%). The evaporation rate is 0.1 nm / s.

[0062] (7) Evaporation of alkali metals

[0063] 1) Bottom K Temperature 180 ℃, K evaporation rate 0.1 A / (3~5 min), until the monitored photocurrent reaches its maximum value.

[0064] 2) K-Sb a stage At a temperature of 180 °C, and maintaining the K evaporation rate, Sb was deposited to 1.6 A at a rate of 0.2 A / min.

[0065] 3) K-Sb b stage At a temperature of 180 ℃, continue adjusting the Sb current at a rate of (0.02~0.05) A / (2~4) min until the photocurrent curve growth angle reaches 45°±15°.

[0066] 4) Evaporation of Cs When the chamber temperature reaches 160 °C, the Cs evaporation current is increased to 4.5 A at a rate of 0.5 A / 3 min, and then increased by 0.5 A every 30 min until it ends at 120 min. Comparative Example 1

[0067] [Alumina film only] The difference from Example 1 is that step (2) is omitted. test

[0068] (a) Macroscopic Testing

[0069] like Figure 4 As shown, the lead fluoride crystal surface in Example 1 showed no blackening lead reducing agent, indicating that the protective film layer of the photoelectric conversion component of the present invention has a good protective effect.

[0070] (ii) Test of the flatness of the light window surface

[0071] The surface flatness of the light window in Example 1 and Comparative Example 1 was tested using an AFM device, and the results are as follows: Figure 5 and Figure 6 As shown.

[0072] The results show that the surface flatness of the light window in Example 1 is very good. The height difference table shows that the vertical fluctuation range does not exceed 5 nm, and the film layer does not peel or fall off. However, the surface flatness of the light window in Comparative Example 1 is poor. Under this condition, the cathode surface will peel up during the manufacturing process, which will not be able to fully protect the light window surface and produce black lead reducing agent.

[0073] This demonstrates that the photoelectric conversion component of the present invention, after the deposition of the double film layer, can fully protect the surface condition of the light window due to the gradient relationship in the coefficient of expansion among the three components and the fact that the alumina is more dense.

[0074] (III) Cathode surface transmittance test

[0075] A comparison of cathode surface transmittance was conducted before and after lead fluoride optical window coating. Before coating, the transmittance of lead fluoride crystal itself was about 85% at a wavelength of 410 nm, while after coating, the transmittance of the lead fluoride mixed film was about 90%, showing a significant increase in transmittance, which can improve the quantum efficiency of the sample tube.

[0076] As can be seen from the above, the photoelectric conversion component of the present invention systematically solves the problems of film failure, excessive light loss and unreliable sealing of large-size lead fluoride crystals under high temperature and high radiation environments by constructing a thermal expansion gradient through a MgF2 transition film layer, synergistic anti-reflection of the double film layer and optimization of the sealing interface.

[0077] The photoelectric conversion component of this invention achieves a breakthrough in triple performance optimization of stress dispersion, light efficiency improvement and sealing enhancement, providing a reliable solution for key devices in fields such as high-energy physics detection and industrial radiation monitoring, and promoting the advancement of lead fluoride crystals from laboratory applications to engineering and industrialization.

[0078] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Those skilled in the art can make various modifications and refinements without departing from the spirit and scope of the invention. Therefore, the scope of protection of the present invention shall be determined by the claims.

Claims

1. A high-temperature resistant photoelectric conversion assembly for a radiation detector, characterized by, The radiation detector comprises a substrate layer, a protective layer and a cathode layer. The substrate layer is a lead fluoride crystal, the lead fluoride crystal has oppositely arranged first and second surfaces, and the first surface is configured as a growth surface, the growth surface comprises a photocathode surface and indium sealing surfaces arranged on both sides of the photocathode surface. The protective layer comprises a magnesium fluoride film and an aluminum oxide film which are sequentially arranged on the growth surface in a direction away from the growth surface. The cathode layer is an alkali metal layer arranged on the aluminum oxide film away from the magnesium fluoride film and corresponding to the photocathode surface.

2. The high-temperature resistant photoelectric conversion assembly for a radiation detector according to claim 1, characterized in that, The thickness ratio of the magnesium fluoride film to the aluminum oxide film is 1:(2-3).

3. The high-temperature resistant photoelectric conversion assembly for a radiation detector according to claim 1 or 2, characterized in that, The thickness of the magnesium fluoride film is 30-50 nm.

4. The high-temperature resistant photoelectric conversion assembly for a radiation detector according to claim 1 or 2, characterized in that, The thickness of the aluminum oxide film is 80-120 nm.

5. The high-temperature resistant photoelectric conversion assembly for a radiation detector according to claim 1, wherein The alkali metal in the alkali metal layer is K-Cs-Sb.

6. The high-temperature resistant photoelectric conversion assembly for a radiation detector according to claim 1, wherein The protective layer on the indium sealing surface is sequentially arranged with a NiCr film, a Cu film and an Ag film.

7. A method of producing a high-temperature resistant photoelectric conversion module for a radiation detector as claimed in any one of claims 1 to 5, characterized in that The method comprises: evaporating a magnesium fluoride film and an aluminum oxide film on the growth surface of the lead fluoride crystal in sequence; then, evaporating a NiCr film, a Cu film and an Ag film on the aluminum oxide film of the indium sealing surface in sequence; finally, evaporating an alkali metal layer on the aluminum oxide film on the photocathode surface.

8. The method of claim 7, wherein the method further comprises: The specific process of evaporating the magnesium fluoride film on the growth surface of the lead fluoride crystal comprises: using atomic deposition technology to evaporate the magnesium fluoride film on the growth surface of the lead fluoride crystal at a temperature of 160-200 DEG C, with dimethyl magnesium and titanium tetrafluoride as reaction sources.

9. The method of claim 7, wherein the method further comprises: depositing a first layer of a first material on the substrate; and depositing a second layer of a second material on the first layer, wherein the first material and the second material are different. The specific process of evaporating the aluminum oxide film on the magnesium fluoride film comprises: using atomic deposition technology to evaporate the aluminum oxide film on the magnesium fluoride film at a temperature of 160-200 DEG C, with trimethyl aluminum and water as reaction sources.

10. A radiation detector, characterized by The photoelectric conversion assembly of the radiation detector is the high-temperature-resistant photoelectric conversion assembly for a radiation detector according to any one of claims 1-6, or is prepared by the method according to any one of claims 7-10.

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