Scintillator material

Abstract

To provide a scintillator material for increasing a film thickness of a nanocomposite layer in which an iodide phosphor is taken into a cristobalite structure and enhancing emission intensity, so as to improve resolution.SOLUTION: A scintillator material (10) which is exited by a radiation so as to emit visible light includes: a base plate (11) which is made of quartz glass and which has a first recess (12a) on a first surface, and a second recess (12b) on a second surface on an opposite side to the first surface; and nanocomposite layers (13a, 13b) which are placed in the first recess (12a) and the second recess (12b) and in which an iodide phosphor is taken into a cristobalite structure.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to a scintillator material. [Background technology]

[0002] Conventionally, radiation detection devices have used iodides such as NaI:Tl and CsI:Tl as scintillator materials that are excited by radiation and emit visible light. Iodide-based scintillator materials are hygroscopic, meaning they absorb moisture from the air and become hydrated, so they need to be sealed in a highly airtight container. In conventional radiation detection devices, the iodide-based scintillator material and the light detection unit were sealed in an aluminum can, a glass window component was bonded to the light outlet, and the light detection unit placed inside the container detected visible light.

[0003] However, because small amounts of water vapor from the outside air could penetrate the container through the adhesive joint between the container and the window component, the iodide-based scintillator would deteriorate due to hydration. Therefore, proper management and maintenance of the radiation detection device were necessary for long-term use. In addition, to suppress the intrusion of moisture into the container, a highly airtight seal was required, which increased the number of steps in the manufacturing process and reduced work efficiency.

[0004] To solve these problems, the iodide phosphor material SrI2:Eu 2+ It has been proposed to improve moisture resistance by incorporating these elements and using a nanocomposite scintillator material (see Patent Documents 1-3, etc.). [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2019-074358 [Patent Document 2] International Publication No. 2021 / 145260 [Patent Document 3] Japanese Patent Publication No. 2022-140222 [Overview of the project] [Problems that the invention aims to solve]

[0006] In conventional scintillation materials, a raw material for iodide phosphor material is filled into a recess in a quartz glass substrate. The raw material melts within the recess, and the molten material penetrates the quartz glass while crystallizing it, forming a nanocomposite layer (luminescent layer) at the bottom of the recess. However, the thickness of the luminescent layer formed by the melting and penetration of the iodide phosphor was limited to about 200 μm or less. As a result, radiation could not be sufficiently absorbed by the nanocomposite layer, and the desired luminescence intensity could not be obtained.

[0007] Therefore, the present invention has been made in view of the above-mentioned conventional problems, and aims to provide a scintillator material that can increase the thickness of the nanocomposite layer in which an iodide phosphor is incorporated into the cristobalite structure, thereby increasing the luminescence intensity and improving resolution. [Means for solving the problem]

[0008] To solve the above problems, the scintillator material of the present invention is a scintillator material that emits visible light when excited by radiation, and is characterized by comprising a substrate made of quartz glass, having a first recess formed on a first surface and a second recess formed on a second surface opposite to the first surface, and a nanocomposite layer in which an iodide phosphor is incorporated into a cristobalite structure within the first recess and the second recess.

[0009] In the scintillator material of the present invention, since a nanocomposite layer is provided in both the first recess and the second recess, it is possible to increase the thickness of the nanocomposite layer across the entire substrate, thereby increasing the light emission intensity and improving the resolution.

[0010] Furthermore, in one aspect of the present invention, the first recess and the second recess have an overlapping region in which at least a portion overlaps in a plan view.

[0011] In addition, in one aspect of the present invention, an intermediate layer made of the quartz glass is provided between the first concave portion and the second concave portion in the overlapping region.

[0012] In addition, in one aspect of the present invention, the intermediate layer has a thickness in the range of 0.5 mm or more and 1.5 mm or less.

[0013] In addition, in one aspect of the present invention, the first concave portion and the second concave portion have a depth in the range of 0.5 mm or more and 2.5 mm or less.

[0014] In addition, in one aspect of the present invention, the substrate has a thickness in the range of 2 mm or more and 6 mm or less.

[0015] In addition, in one aspect of the present invention, the iodide phosphor is M ii I2:Eu 2+ (M ii :Ca 2+ ,Sr 2+ )

Advantages of the Invention

[0016] In the present invention, it is possible to provide a scintillator material capable of increasing the film thickness of the nanocomposite layer in which the iodide phosphor is incorporated in the cristobalite structure, enhancing the emission intensity, and improving the resolution.

Brief Description of the Drawings

[0017] [Figure 1] It is a schematic cross-sectional view showing a structural example of a scintillator material 10 according to the first embodiment. [Figure 2] It is a process diagram schematically showing a manufacturing method of the scintillator material 10 according to the first embodiment. [Figure 3] It is a schematic diagram showing a structure of a radiation detection device 100 using the scintillator material 10. [Figure 4] It is a graph showing the overall thicknesses of the nanocomposite layers 13a and 13b in Examples 1-4 and the comparative example. [Figure 5] This is a schematic diagram showing the overview of an apparatus for measuring the luminescence performance of a scintillator material 10 by irradiation with gamma rays. [Figure 6] This graph shows the relative emission intensity of the scintillator material 10 after gamma ray irradiation in Examples 1-4 and the comparative example. [Figure 7] This is a schematic process diagram showing the manufacturing method of the scintillator material 10 according to the second embodiment. [Modes for carrying out the invention]

[0018] (First Embodiment) Hereinafter, a first embodiment of the present invention will be described in detail with reference to the drawings. The same or equivalent components, members, and processes shown in each drawing will be denoted by the same reference numerals, and redundant explanations will be omitted as appropriate. Figure 1 is a schematic cross-sectional view showing an example of the structure of the scintillator material 10 according to this embodiment. As shown in Figure 1, the scintillator material 10 according to this embodiment has a structure in which recesses 12a and 12b are formed on both sides of the substrate 11, and nanocomposite layers 13a and 13b are provided in each recess 12a and 12b.

[0019] The substrate 11 is a roughly plate-shaped member made of quartz glass, with recesses 12a and 12b formed on one side (first surface) and the opposite side (second surface), respectively. The thickness of the substrate 11 is not limited, but it is preferable to have a thickness of 2 mm or more. If the substrate 11 is thinner than 2 mm, it is not possible to secure sufficient depth for the recesses 12a and 12b formed on both sides, making it difficult to adequately fill with raw materials for forming the nanocomposite layers 13a and 13b. Furthermore, it is preferable that the substrate 11 has a thickness of 6 mm or less. If the substrate 11 is thicker than 6 mm, the amount of light propagating laterally from the sides of the recesses 12a and 12b into the interior of the substrate 11 increases, reducing the resolution of the scintillator material 10.

[0020] Furthermore, the substrate 11 has an overlapping region in which at least a portion of the recesses 12a and 12b overlap in a plan view, and an intermediate layer 11a is provided between the recesses 12a and 12b in the overlapping region. The intermediate layer 11a is made of quartz glass that constitutes the substrate 11 and is the portion that remained without the iodide phosphor when the nanocomposite layers 13a and 13b were formed. In the example shown in Figure 1, the recesses 12a and 12b are formed at the same size and in the same position, but the sizes of the recesses 12a and 12b may be different, and the recesses 12a or 12b may extend to a region different from the overlapping region in a plan view. The presence of the intermediate layer 11a between the recesses 12a and 12b ensures the strength to hold the nanocomposite layers 13a and 13b.

[0021] The thickness of the intermediate layer 11a is not limited, but it is preferable that it has a thickness of 0.5 mm or more. If the intermediate layer 11a is thinner than 0.5 mm, it will lack the strength necessary to hold the nanocomposite layers 13a and 13b, and the nanocomposite layers 13a and 13b may detach from the recesses 12a and 12b. Furthermore, it is preferable that the intermediate layer 11a has a thickness of 1.5 mm or less. If the intermediate layer 11a is thicker than 1.5 mm, the amount of light propagating laterally through the intermediate layer 11a will increase, reducing the resolution of the scintillator material 10.

[0022] The recesses 12a and 12b are recessed shapes formed on one and the opposite surface of the substrate 11 with predetermined area and depth. While the recesses 12a and 12b can be approximately cylindrical, their shape is not limited, and conical, polygonal prism, or polygonal pyramidal shapes may also be used. In this embodiment, the recesses 12a and 12b correspond to the first and second recesses in the present invention, respectively. Figure 1 shows an example where one recess 12a or 12b is provided on the substrate 11 for simplification of the explanation, but multiple recesses 12a and 12b may be formed within the surface of the substrate 11. The diameters of the recesses 12a and 12b are not limited and can be appropriately set according to the application of the scintillator material 10 and the conditions of mechanical processing.

[0023] The depths of the recesses 12a and 12b are not limited, but it is preferable that they have a depth of 0.5 mm or more. If the recesses 12a and 12b are shallower than 0.5 mm, the raw materials for forming the nanocomposite layers 13a and 13b cannot be sufficiently filled, and nanocomposite layers 13a and 13b with a sufficient thickness capable of absorbing radiation cannot be obtained. Further, it is preferable that the recesses 12a and 12b have a depth of 2.5 mm or less. If the recesses 12a and 12b are deeper than 2.5 mm, due to the restriction of the aspect ratio by the machining accuracy during cutting, the minimum diameter of the recesses 12a and 12b becomes large, and it becomes difficult to increase the resolution by reducing the area of the nanocomposite layers 13a and 13b.

[0024] The nanocomposite layers 13a and 13b are layers in which an iodide phosphor is incorporated into a cristobalite structure, provided at the bottoms of the recesses 12a and 12b, respectively. Details regarding the materials and manufacturing methods of the nanocomposite layers 13a and 13b will be described later, but an iodide phosphor is a compound represented by the general formula M ii I2:Eu 2+ (M ii :Ca 2+ ,Sr 2+ )

[0025] Next, the nanocomposite layers 13a and 13b in which an iodide phosphor is incorporated into a cristobalite structure will be described in more detail. Silica has an amorphous structure with a basic skeleton in which SiO4 tetrahedrons are connected by Si-O-Si bonds. The bond angle of Si-O-Si has an angle of 145° ± 10°. When silica is heated, the thermal expansion rate is small up to around 1000 °C, but starts to gently increase from around when it exceeds 1000 °C. This is because active hydrogen is generated from the OH groups on the silica surface, and bond cleavage and rearrangement of Si-O-Si bonds occur in part of the silica. At this time, the bond angle of Si-O-Si becomes 180°, and large voids occur in the SiO4 connection network. These voids are Sr 2+ ,Cs + ,Ca 2+ ,Eu 2+ ,Tl +These ions act as pockets for cations of metals and anions of halogens, and these ions are incorporated into the SiO4 network.

[0026] The incorporated ions undergo thermal diffusion, causing cations and anions to bond and form ionic crystal nuclei. It is thought that the formation of these ionic crystal nuclei triggers the crystallization of the silica in the matrix phase, resulting in the formation of cristobalite. In this manner, the incorporation of luminescent metal halide salts and the crystallization of SiO2 occur in parallel, leading to the formation of nanocomposite layers 13a and 13b in which iodide phosphors are incorporated into the cristobalite structure.

[0027] Figure 2 is a schematic process diagram showing the manufacturing method of the scintillator material 10 according to this embodiment. In Figure 2, an example is shown in which one recess 12a and one recess 12b are formed on both sides of the substrate 11 shown in Figure 1, but the scintillator material 10 can be obtained by performing the same process even when multiple recesses 12a and 12b are formed on both sides.

[0028] First, in the substrate preparation process, a plate-shaped substrate 11 made of quartz glass is prepared as shown in Figure 2(a), and recesses 12a and 12b with a diameter D and depth H are formed on the front and back surfaces of the substrate 11. The method for forming the recesses 12a and 12b is not limited, but in order to form deeper recesses 12a and 12b, it is preferable to form them by mechanical processing using a micromachining center or the like.

[0029] Next, in the raw material powder preparation step, the iodide raw material powder and the SiO2 fine particle powder are mixed to obtain raw material powders 14a and 14b. As the iodide raw material, M ii I2(M ii :Ca 2+ ,Sr 2+ ) and EuI2 are examples. Here, M iiThe ratio of EuI2 to I2 is preferably between 5 mol% and 15 mol%. If the ratio of EuI2 is less than 5 mol%, the density of luminescent elements in the emissive layer decreases, making it difficult to improve the luminescence intensity. Conversely, if the ratio of EuI2 is more than 15 mol%, concentration quenching occurs due to buffering between luminescent elements, making it difficult to improve the luminescence intensity.

[0030] Furthermore, iodide raw materials include M, for the purpose of supplementing the easily volatile element I. i I(M i :NH4 + ,Li + Na + ,K + ) may be added. Here, M i The amount of I added is the divalent metal ion (M ii +Eu 2+ ) is preferably 1 mol% to 120 mol%. i If the amount of I added is less than 1 mol%, there is no iodine replenishment effect, crystal defects due to iodine deficiency occur, and the X-ray emission intensity decreases. Also, M i If the amount of I added is greater than 120 mol%, the amount of iodide raw material necessary to fill the recesses 12a and 12b and form the light-emitting layer becomes relatively small, making it difficult to form the nanocomposite layers 13a and 13b with sufficient thickness.

[0031] Furthermore, the average particle size (D50) of the SiO2 fine particles is preferably in the range of 0.1 μm to 10 μm. If the average particle size of the SiO2 fine particles is smaller than 0.1 μm, the particles will be too fine and bulky, making it difficult to fill the recesses 12a and 12b. Also, if the average particle size of the SiO2 fine particles is larger than 10 μm, the specific surface area of ​​the particles will be small, reducing reactivity and potentially resulting in insufficient formation of the nanocomposite layers 13a and 13b. The method of forming the SiO2 fine particles is not limited, and those obtained by known methods such as melting, sol-gel, and sedimentation can be used. Alternatively, a powdered phosphor material, which is a nanocomposite of an iodide raw material, may be used as the SiO2 fine particles.

[0032] Furthermore, the SiO2 fine particle content in the raw material powders 14a and 14b is preferably 10 mol% to 600 mol% relative to the iodide raw material. If the SiO2 fine particle content is less than 10 mol%, the iodide raw material will expand in volume during firing of the nanocomposite layers 13a and 13b, overflowing from the recesses 12a and 12b, causing the formation area of ​​the nanocomposite layers 13a and 13b to extend beyond the recesses 12a and 12b, potentially reducing the resolution during radiation detection. If the SiO2 fine particle content is greater than 600 mol%, the nanocomposite formation of the iodide raw material may proceed too far with the SiO2 fine particles, potentially resulting in insufficient integration with the quartz glass of the substrate 11.

[0033] Next, in the first material filling step shown in Figure 2(b), the raw material powder 14a prepared in the raw material powder preparation step is filled into the recess 12a. A lid 15 is then placed on the substrate 11 to cover the recess 12a. The lid 15 is not limited to any material that can withstand the heating in the nanocomposite formation step described later and does not react with the raw material powders 14a and 14b; for example, a sapphire substrate can be used.

[0034] Next, in the first nanocomposite formation step shown in Figure 2(c), the substrate 11 on which the lid 15 is placed is heated to react the iodide raw material with the quartz glass and SiO2 fine particles constituting the substrate 11, thereby forming a nanocomposite layer 13a in which iodide phosphors are incorporated into the cristobalite structure. Here, it is preferable to use a nitrogen atmosphere containing hydrogen when carrying out the nanocomposite formation step. Furthermore, the heating temperature is preferably in the range of 850 to 1000°C.

[0035] Next, in the second material filling step shown in Figure 2(d), the substrate 11 is turned over and the raw material powder 14b prepared in the raw material powder preparation step is filled into the recess 12b. A lid 15 is then placed on the substrate 11 to cover the recess 12b.

[0036] Next, in the second nanocomposite formation step shown in Figure 2(e), the substrate 11 on which the lid 15 is placed is heated to react the iodide raw material with the quartz glass and SiO2 fine particles constituting the substrate 11, thereby forming a nanocomposite layer 13b in which iodide phosphors are incorporated into the cristobalite structure.

[0037] By using the manufacturing method of this embodiment shown in Figures 2(a) to 2(e), a scintillator material 10 is obtained in which recesses 12a and 12b are provided on both sides of the substrate 11, nanocomposite layers 13a and 13b are provided at the bottom of the recesses 12a and 12b, and an intermediate layer 11a is provided between the nanocomposite layers 13a and 13b.

[0038] In the first and second material filling steps shown in Figures 2(b) and 2(d), the raw material powder 14a and 14b may be tapped into the recesses 12a and 12b after filling them with the powder, or pre-formed tablet-shaped raw material powder 14a and 14b may be placed inside the recesses 12a and 12b. The amount of raw material powder 14a and 14b to be filled into the recesses 12a and 12b is not limited, but it is preferable, and more preferably 60% or less, to fill the recesses 12a and 12b to 80% or less of the depth H of the recesses 12a and 12b so that the iodide raw material does not overflow from the recesses 12a and 12b during firing. In addition, a small amount of alkali halide may be added to the recesses 12a and 12b to promote the integration of the quartz glass and SiO2 fine particles that constitute the substrate 11.

[0039] In the first and second nanocomposite formation steps shown in Figures 2(c) and 2(e), the reaction between the iodide raw material and SiO2 fine particles, and the reaction between the iodide raw material and the quartz glass constituting the substrate 11 proceed within the recesses 12a and 12b, resulting in nanocomposite layers 13a and 13b integrated with the substrate 11. Furthermore, since the raw material powders 14a and 14b are mixed with iodide raw material and SiO2 fine particles, the volume expansion of the iodide raw material during heating (for example, due to a bumping phenomenon) and overflow from the recesses 12a and 12b are suppressed. In addition, in the nanocomposite formation step, the heat treatment is performed with the recesses 12a and 12b covered by the lid 15, which suppresses the volatilization of iodine, suppresses iodine deficiency in the iodide phosphor, makes it possible to obtain an iodide phosphor with good crystallinity, and also allows for thicker nanocomposite layers 13a and 13b.

[0040] Figure 3 is a schematic diagram showing the structure of a radiation detection device 100 using a scintillator material 10. As shown in Figure 3, the radiation detection device 100 comprises a scintillator material 10, a container 20, a window member 30, a photomultiplier tube 40 (PMT), a bleeder circuit 50, and a light-shielding case 60.

[0041] The container 20 is a substantially cylindrical member having an opening, and houses the scintillator material 10 inside. It is connected to the photomultiplier tube 40 and the bleeder circuit 50 within the light-shielding case 60. A window member 30 is airtightly fixed to the opening with adhesive or the like. The material constituting the container 20 is not limited, but aluminum can be used as an example. Furthermore, the shape of the container 20 is not limited to a cylindrical shape and can be appropriately designed according to the shape and size of each component housed inside. The container 20 also has wiring holes (not shown), and wiring is connected to the bleeder circuit 50 from the outside through these wiring holes.

[0042] The window member 30 is a plate-shaped member made of a material that transmits light from the scintillator material 10, and is placed in the opening of the container 20 to hermetically seal the inside of the container 20. The material that makes up the window member 30 is not limited, and known glass materials can be used. The space between the outer circumference of the window member 30 and the opening of the container 20 is sealed hermetically to prevent water vapor from entering through the gap.

[0043] The photomultiplier tube 40 is a component that detects minute amounts of photons and outputs an electrical signal. The structure of the photomultiplier tube 40 can be one of known types; for example, a structure can be used in which a photocathode, multiple secondary electron multiplier electrodes (dynodes), an anode, and other electrodes are sealed in a high-vacuum glass container. A scintillator material 10 is placed on the entrance window side of the photomultiplier tube 40, and a bleeder circuit 50 is connected to the output side.

[0044] The bleeder circuit 50 is a component that supplies voltage from a high-voltage power supply to the photomultiplier tube 40 via multiple divider resistors and outputs current from the photomultiplier tube 40. Multiple voltages from the high-voltage power supply are supplied to each dynode of the photomultiplier tube 40. The output of the bleeder circuit 50 is transmitted as a detection signal to an external signal processing unit via wiring (not shown).

[0045] The light-shielding case 60 is a case-shaped component made of a light-shielding material, and houses the container 20, the window member 30, the scintillator material 10, the photomultiplier tube 40, and the bleeder circuit 50 inside. Although not shown in Figure 1, the light-shielding case 60 is provided with a hole for bringing the wiring of the bleeder circuit 50 to the outside.

[0046] In the radiation detection device 100 shown in Figure 3, when radiation such as gamma rays passes through the light-shielding case 60 and the container 20 and enters the scintillator material 10, the phosphor material in the scintillator material 10 is excited and emits blue light with a wavelength range of 380 nm to 500 nm. The blue light photons emitted from the scintillator material 10 pass through the window member 30 and reach the photocathode of the photomultiplier tube 40, where they are converted into electrons. When the electrons generated at the photocathode collide with a dynode, a large number of electrons are emitted due to the voltage applied to the dynode, and electron emission occurs in a chain reaction between multiple dynodes, amplifying the electrons generated by one photon like an avalanche. The current generated by the electrons amplified in the photomultiplier tube 40 is transmitted as a detection signal to an external signal processing unit via the bleeder circuit 50, and the signal processing unit calculates the number of photons from the relationship between the photons, current and detection signal. The signal processing unit also calculates the radiation intensity from the calculated number of photons.

[0047] (Example 1) The scintillator material 10 according to Example 1 has a cristobalite structure and a phosphor material CaI2:Eu 2+ This is what was incorporated. In the substrate preparation process, a substrate 11 made of quartz glass with a thickness of 4 mm and a square of 15 mm on each side was prepared, and recesses 12a and 12b with a diameter D of 10 mm and a depth H of 1.5 mm were formed on the front and back surfaces of the substrate 11 by grinding, and it was dried in an oven at 200°C for 2 hours. In the raw material powder preparation process, CaI2 / EuI2 / NH4I, which are iodide raw materials, were accurately weighed in an inert gas Ar atmosphere in a glove box with a dew point temperature of -30°C or lower, and crushed and mixed in a quartz mortar. In addition, SiO2 fine particles with an average particle size of 3 μm obtained by the melting method were prepared, and the iodide raw material powder and SiO2 fine particles were mixed so that the molar ratio of CaI2 / EuI2 / NH4I / SiO2 was 0.9 / 0.1 / 1.1 / 0.2 to obtain raw material powders 14a and 14b.

[0048] In the first and second material filling steps, the obtained 0.20 g raw material powders 14a and 14b were molded into 9 mm diameter tablet shapes and placed in the recesses 12a and 12b. In the lid placement step, a 15 mm square sapphire substrate was prepared as a lid 15 and used to cover each recess 12a and 12b. In the first and second nanocomposite formation steps, the substrate 11 was heated at 1000°C for 10 hours in a hydrogen-containing nitrogen atmosphere with H2 / N2 = 5 / 95 to perform firing. After that, the substrate was ultrasonically cleaned with 40°C warm pure water to remove excess iodide, thereby obtaining the scintillator material 10 of Example 1 in which nanocomposite layers 13a and 13b were formed in the recesses 12a and 12b.

[0049] (Example 2) The scintillator material 10 according to Example 2 has a cristobalite structure with a phosphor material CaI2:Eu 2+ The material incorporates alkali metal ions, including Na. In the substrate preparation process, a substrate 11 made of quartz glass with a thickness of 2.5 mm and a square area of ​​15 mm on each side was prepared. By grinding, recesses 12a and 12b with a diameter D of 10 mm and a depth H of 0.6 mm were formed on the front and back surfaces of the substrate 11, and the substrate was dried in an oven at 200°C for 2 hours. In the raw material powder preparation process, CaI2 / EuI2 / NaI, which are iodide raw materials, were accurately weighed in an inert gas Ar atmosphere in a glove box with a dew point temperature of -30°C or lower, and crushed and mixed in a quartz mortar. In addition, SiO2 fine particles with an average particle size of 10 μm obtained by the melting method were prepared, and the iodide raw material powder and SiO2 fine particles were mixed so that the molar ratio of CaI2 / EuI2 / NaI / SiO2 was 0.85 / 0.15 / 0.08 / 5.0 to obtain raw material powders 14a and 14b.

[0050] In the first and second material filling steps, the obtained 0.12 g raw material powders 14a and 14b were packed into the recesses 12a and 12b by tapping. In the lid placement step, a sapphire substrate with a square diameter of 15 mm was prepared as a lid 15 and covered each recess 12a and 12b. In the first and second nanocomposite formation steps, the substrate 11 was fired by heating at 1000°C for 8 hours in a hydrogen-containing nitrogen atmosphere with H2 / N2 = 5 / 95. After that, the substrate was ultrasonically cleaned with warm pure water at 40°C to remove excess iodide, thereby obtaining the scintillator material 10 of Example 2 in which nanocomposite layers 13a and 13b were formed in the recesses 12a and 12b.

[0051] (Example 3) The scintillator material 10 according to Example 3 has a cristobalite structure with a phosphor material CaI2:Eu 2+ It incorporates and contains K as an alkali metal ion. In the substrate preparation process, a substrate 11 made of quartz glass with a thickness of 5 mm and a square of 15 mm on each side was prepared, and recesses 12a and 12b with a diameter D of 10 mm and a depth H of 2 mm were formed on the front and back surfaces of the substrate 11 by grinding, and it was dried in an oven at 200°C for 2 hours. In the raw material powder preparation process, CaI2 / EuI2 / KI, which are iodide raw materials, were accurately weighed in an inert gas Ar atmosphere in a glove box with a dew point temperature of -30°C or lower, and crushed and mixed in a quartz mortar. In addition, SiO2 fine particles with an average particle size of 0.12 μm obtained by the sol-gel method were prepared, and the iodide raw material powder and SiO2 fine particles were mixed so that the molar ratio of CaI2 / EuI2 / KI / SiO2 was 0.95 / 0.05 / 0.05 / 0.3 to obtain raw material powders 14a and 14b.

[0052] In the first and second material filling steps, the obtained 0.12 g raw material powders 14a and 14b were packed into the recesses 12a and 12b by tapping. In the lid placement step, a sapphire substrate with a square diameter of 15 mm was prepared as a lid 15 and covered each recess 12a and 12b. In the first and second nanocomposite formation steps, the substrate 11 was fired by heating at 980°C for 20 hours in a hydrogen-containing nitrogen atmosphere with H2 / N2 = 5 / 95. After that, the substrate was ultrasonically cleaned with warm pure water at 40°C to remove excess iodide, thereby obtaining the scintillator material 10 of Example 3 in which nanocomposite layers 13a and 13b were formed in the recesses 12a and 12b.

[0053] (Example 4) The scintillator material 10 according to Example 4 has a cristobalite structure with a phosphor material SrI2:Eu 2+ It incorporates and contains Li as an alkali metal ion. In the substrate preparation process, a substrate 11 made of quartz glass with a thickness of 3 mm and a square of 15 mm on each side was prepared, and recesses 12a and 12b with a diameter D of 10 mm and a depth H of 1 mm were formed on the front and back surfaces of the substrate 11 by grinding, and it was dried in an oven at 200°C for 2 hours. In the raw material powder preparation process, SrI2 / EuI2 / LiI, which are iodide raw materials, were accurately weighed in an inert gas Ar atmosphere in a glove box with a dew point temperature of -30°C or lower, and crushed and mixed in a quartz mortar. In addition, SiO2 fine particles with an average particle size of 0.7 μm obtained by the sedimentation method were prepared, and the iodide raw material powder and SiO2 fine particles were mixed so that the molar ratio of SrI2 / EuI2 / LiI / SiO2 was 0.9 / 0.1 / 0.02 / 1.0 to obtain raw material powders 14a and 14b.

[0054] In the first and second material filling steps, the obtained 0.15 g raw material powders 14a and 14b were packed into the recesses 12a and 12b by tapping. In the lid placement step, a sapphire substrate was prepared as a lid 15, with a square diameter of 15 mm and a cylindrical protrusion in the center with a diameter of 9.5 mm and a height of 0.5 mm. The substrate was used to cover the recesses 12a and 12b so that the cylindrical protrusion fit into it. In the first and second nanocomposite formation steps, the substrate 11 was fired by heating at 880°C for 5 hours in a hydrogen-containing nitrogen atmosphere with H2 / N2 = 5 / 95. After that, the substrate was ultrasonically cleaned with warm pure water at 40°C to remove excess iodide, thereby obtaining the scintillator material 10 of Example 4 in which nanocomposite layers 13a and 13b were formed in the recesses 12a and 12b.

[0055] (Comparative example) The scintillator material 10 in the comparative example has a cristobalite structure with a phosphor material CaI2:Eu 2+ This is what was incorporated. In the substrate preparation process, a substrate 11 made of quartz glass with a thickness of 4 mm and a square of 15 mm on each side was prepared, and only a recess 12a with a diameter D of 10 mm and a depth H of 1.5 mm was formed on the surface of the substrate 11 by grinding, and it was dried in an oven at 200°C for 2 hours. In the raw material powder preparation process, CaI2 / EuI2 / NH4I, which are iodide raw materials, were accurately weighed in an inert gas Ar atmosphere in a glove box with a dew point temperature of -30°C or lower, and crushed and mixed in a quartz mortar. In addition, SiO2 fine particles with an average particle size of 3 μm obtained by the melting method were prepared, and the iodide raw material powder and SiO2 fine particles were mixed so that the molar ratio of CaI2 / EuI2 / NH4I / SiO2 was 0.9 / 0.1 / 1.1 / 0.2 to obtain raw material powder 14a.

[0056] In the first material filling step, the obtained 0.20 g raw material powder 14a was molded into a tablet shape with a diameter of 9 mm and placed in the recess 12a. In the lid placement step, a sapphire substrate with a square diameter of 15 mm was prepared as a lid 15 and covered the recess 12a. In the first nanocomposite formation step, the substrate 11 was heated at 1000°C for 10 hours in a hydrogen-containing nitrogen atmosphere with H2 / N2 = 5 / 95 to perform firing. After that, the substrate was ultrasonically cleaned with warm pure water at 40°C to remove excess iodide, thereby obtaining a comparative example scintillator material 10 in which a nanocomposite layer 13a was formed in the recess 12a.

[0057] (Film thickness of nanocomposite layers 13a and 13b) The thickness of the recesses 12a and 12b at their centers was measured before the first material filling process and after the formation of the nanocomposite layers 13a and 13b, and the film thickness of the nanocomposite layers 13a and 13b was calculated. A digital length measuring instrument was used to measure the film thickness. The difference in film thickness before and after the formation of the nanocomposite layers 13a and 13b was defined as the total film thickness of the nanocomposite layers 13a and 13b.

[0058] Figure 4 is a graph showing the total thickness of the nanocomposite layers 13a and 13b in Examples 1-4 and the Comparative Example. As shown in Figure 4, the thickness of the nanocomposite layers 13a and 13b increased by more than 400 μm in Examples 1-4, while the increase in the Comparative Example was less than 400 μm.

[0059] (Luminescence properties due to radiation excitation) Figure 5 is a schematic diagram showing the outline of an apparatus for measuring the luminescence performance of a scintillator material 10 by gamma ray irradiation. In the measurement apparatus shown in Figure 5, the scintillator material 10 is set in a photomultiplier tube 40, and gamma rays are irradiated from a radiation source 80 via a lead collimator 70. In the scintillator material 10, the phosphor material in the nanocomposite layer 13 is excited by the gamma rays and emits light at a peak wavelength of 430 nm. This luminescence from the scintillator material 10 is measured by the photomultiplier tube 40. The radiation source 80 is: 137 A 662keV Cs sample was used.

[0060] Figure 6 is a graph showing the relative emission intensity of the scintillator material 10 after gamma ray irradiation in Examples 1-4 and the Comparative Example. In Figure 6, the relative emission intensity is shown with the emission intensity of the Comparative Example as the reference. As shown in Figure 6, the emission intensity in Examples 1-4 is improved to 1.4 to 2.1 times that of the Comparative Example. This is the same trend as the total film thickness of the nanocomposite layers 13a and 13b shown in Figure 4. Therefore, it is thought that in Examples 1-4, light is emitted from the nanocomposite layers 13a and 13b formed in the recesses 12a and 12b on both sides of the substrate 11, resulting in improved emission intensity. In contrast, in the Comparative Example, light is emitted only from the nanocomposite layer 13a formed in the recess 12a, so it is thought that sufficient emission intensity is not obtained.

[0061] As described above, in the scintillator material 10 of this embodiment, nanocomposite layers 13a and 13b are provided in the recesses 12a and 12b on both sides of the substrate 11, respectively. Therefore, it is possible to increase the thickness of the nanocomposite layers 13a and 13b across the entire substrate 11, thereby increasing the light emission intensity and improving the resolution.

[0062] (Second Embodiment) Next, a second embodiment of the present invention will be described with reference to Figure 7. Details that overlap with the first embodiment will be omitted from the explanation. Figure 7 is a schematic process diagram showing the manufacturing method of the scintillator material 10 according to this embodiment. This embodiment differs from the first embodiment in that, after filling the recesses 12a and 12b with raw material powders 14a and 14b, a nanocomposite formation process is carried out collectively to form nanocomposite layers 13a and 13b.

[0063] First, in the substrate preparation process, a plate-shaped substrate 11 made of quartz glass is prepared as shown in Figure 7(a), and recesses 12a and 12b with a diameter D and a depth H are formed on the front and back surfaces of the substrate 11. Next, in the raw material powder preparation process, iodide raw material powder and SiO2 fine particle powder are mixed to obtain raw material powders 14a and 14b.

[0064] Next, in the first material filling step shown in Figure 7(b), the raw material powder 14a prepared in the raw material powder preparation step is filled into the recess 12a. A lid 15a is also placed on the substrate 11 to cover the recess 12a. Next, in the inversion step shown in Figure 7(c), the substrate 11 is inverted with the recess 12a covered by the lid 15a so that the recess 12b faces upwards. Next, in the second material filling step shown in Figure 7(d), the raw material powder 14b prepared in the raw material powder preparation step is filled into the recess 12b. A lid 15b is also placed on the substrate 11 to cover the recess 12b.

[0065] Next, in the nanocomposite formation process shown in Figure 7(d), the substrate 11 on which the lids 15a and 15b are placed is heated to react the iodide raw material with the quartz glass and SiO2 fine particles constituting the substrate 11, thereby forming nanocomposite layers 13a and 13b in which iodide phosphors are incorporated into the cristobalite structure.

[0066] By using the manufacturing method of this embodiment shown in Figures 7(a) to 7(e), a scintillator material 10 is obtained in which recesses 12a and 12b are provided on both sides of the substrate 11, nanocomposite layers 13a and 13b are provided at the bottom of the recesses 12a and 12b, and an intermediate layer 11a is provided between the nanocomposite layers 13a and 13b.

[0067] Even in the scintillator material 10 manufactured using the manufacturing method of this embodiment, since nanocomposite layers 13a and 13b are provided in the recesses 12a and 12b on both sides of the substrate 11, it is possible to increase the thickness of the nanocomposite layers 13a and 13b across the entire substrate 11, thereby increasing the light emission intensity and improving the resolution.

[0068] The present invention is not limited to the embodiments described above, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. [Explanation of Symbols]

[0069] 100...Radiation detection device 10... Scintillator material 11… Circuit board 11a…Middle layer 12a, 12b…recess 13a, 13b… Nanocomposite layer 14a,14b...Raw material powder 15,15a,15b…Lid body 20…Container 30... Window components 40…Photomultiplier tube 50... Bleeder circuit 60… Light-blocking case 70…Lead collimator 80…Radiation source

Claims

1. A scintillator material that emits visible light when excited by radiation, A substrate made of quartz glass, having a first recess formed on its first surface and a second recess formed on its second surface opposite to the first surface, A scintillator material characterized by comprising a nanocomposite layer in which an iodide phosphor is incorporated into a cristobalite structure, within the first recess and the second recess.

2. A scintillator material according to claim 1, A scintillator material characterized in that the first recess and the second recess have an overlapping region in which at least a portion overlaps in a plan view.

3. The scintillator material according to claim 2, The scintillator material is characterized in that an intermediate layer made of quartz glass is provided between the first recess and the second recess in the superimposed region.

4. The scintillator material according to claim 3, The scintillator material is characterized in that the intermediate layer has a thickness in the range of 0.5 mm to 1.5 mm.

5. A scintillator material according to claim 1, The scintillator material is characterized in that the first recess and the second recess have a depth in the range of 0.5 mm to 2.5 mm.

6. A scintillator material according to claim 1, The aforementioned substrate is a scintillator material characterized by having a thickness in the range of 2 mm to 6 mm.

7. A scintillator material according to any one of claims 1 to 6, The iodide phosphor, M ｉｉ I ２ :Eu ２＋ (M ｉｉ : Ca ２＋ , Sr ２＋ A scintillator material characterized by being ).

Images