JP2016109524A - Manufacturing methods for scintillator plate and for radiation detector having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method for a scintillator plate that offers reduced variation in indium iron concentration in a thickness direction thereof, and a manufacturing method for a radiation detector having such a scintillator plate.SOLUTION: A method of manufacturing a scintillator plate includes the steps of: placing a melt 16 of a scintillator material and an indium melt 15 separated from the scintillator material in a container 12 to be in contact with each other; placing the container 12 and a substrate 13 such that the melt 16 of the scintillator material placed in the container is positioned between the indium melt 15 and the substrate 13; and vapor-depositing the melt 16 of the scintillator material, located between the indium melt 15 and the substrate 13, onto the substrate 13.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a scintillator plate and a method of manufacturing a radiation detector including the scintillator plate.

  In the medical field or the like, an indirect flat panel detector (FPD) is widely used as a radiation detector. In the indirect FPD, X-rays that have passed through a subject are absorbed by a scintillator, and the light intensity can be detected by detecting light emitted by the scintillator with a light receiving sensor. The light receiving sensitivity of the light receiving sensor is generally high in the visible to near infrared wavelength region. On the other hand, light emission of cesium iodide, which is one of typical scintillator materials, exists in the vicinity of a wavelength of 300 nm, and light emission from the visible region to the near infrared region is weak. Therefore, it is a general practice to shift the emission wavelength to a wavelength region where the sensitivity of the light receiving sensor is high by adding a small amount of another element to the cesium iodide as the emission center.

  As one of scintillator materials in which a small amount of a luminescent center is added to cesium iodide, indium activated cesium iodide in which a small amount of monovalent indium is added can be given. Indium-activated cesium iodide is contained in a small amount in the base crystal with the cesium iodide as the base crystal and the indium element in an ion state. The emission wavelength region is widely present around 550 nm, which is known to be emitted by monovalent indium ions. Although cesium iodide is taken as an example of the host crystal, this is not limited to cesium iodide. Even in the case where another alkali metal halide material such as cesium bromide (CsBr), rubidium bromide (RbBr), or rubidium iodide (RbI) is a host crystal, light emission in the visible region based on indium ions as described above. Is recognized.

  Patent Document 1 describes a method of manufacturing a scintillator plate by melting and depositing a mixture of cesium iodide and a material that becomes a light emission center, and an indium compound is described as an example of the material that becomes a light emission center. ing. In general, a halide compound is used as the emission center of the alkali metal halide material.

  The concentration of indium ions contained in the scintillator has a correlation with the emission intensity. If the concentration of indium ions is too low, the ratio of converting the energy of X-rays absorbed by the scintillator base crystal into light emission by indium ions becomes small, and the light emission intensity in the visible region as the scintillator is weakened. On the other hand, when the concentration of indium ions is too high, indium halide (such as indium iodide) is likely to be deposited. This precipitate absorbs part of the visible light. Therefore, even in this case, the light emission intensity in the visible range as the scintillator is weakened. That is, the concentration of indium ions contained in the scintillator has a preferable range.

Japanese Patent No. 5407140

  Indium compounds have a considerably higher vapor pressure than alkali metal halides used as scintillator materials. For this reason, as described in Patent Document 1, when the scintillator material and the indium compound are placed in the same vapor deposition vessel and heat-deposited, the indium compound evaporates more than the scintillator material. As a result, the concentration of indium ions in the thickness direction of the deposited layer is uneven, the concentration of indium ions tends to be excessive in the scintillator layer at the initial stage of deposition, and the concentration of indium ions is too low (the concentration is 0 in the scintillator layer at the end of deposition). Including).

  Therefore, the present invention provides a scintillator plate that can reduce the deviation of the concentration of indium ions in the vapor deposition layer thickness direction, and a method of manufacturing a radiation detector including the scintillator plate. By reducing the deviation of the concentration of indium ions in the thickness direction of the deposited layer, the concentration of indium ions in the scintillator layer at the beginning of deposition and the concentration of indium ions in the scintillator layer at the end of deposition can be easily brought closer to the preferred indium ion concentration range. Become. Therefore, it is considered that the emission intensity is easily increased.

  A method of manufacturing a scintillator plate according to one aspect of the present invention includes a step of arranging a melt of a scintillator material and an indium melt separated from the scintillator material in a container so that they are in contact with each other; A step of disposing the container and the substrate such that a melt of the scintillator material disposed between the indium melt and the substrate is disposed between the indium melt and the substrate. Vapor-depositing the melt of the scintillator material on the substrate.

  Other aspects of the present invention will be clarified in the embodiments described below.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of a radiation detector provided with the scintillator plate which can reduce the deviation of the density | concentration of the indium ion in a vapor deposition layer thickness direction, and this scintillator plate can be provided.

Schematic diagram of a vapor deposition apparatus according to an embodiment The figure which shows the X-ray excitation light emission spectrum of the vapor deposition film produced in the Example The cross-sectional schematic diagram of the radiation detector which concerns on embodiment.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. In this embodiment, scintillator material and indium are used as vapor deposition materials, and the scintillator material melt and the indium melt are disposed in the same container. The melt of the scintillator material and the melt of indium are arranged in the container so as to be in contact with each other. However, the melt of indium is not mixed with the melt of the scintillator material, and is thus separated in the container. Then, the melt of the scintillator material is deposited on the substrate in a state where the melt of the scintillator material is disposed between the melt of indium and the substrate. As a result, the melt of the scintillator material plays a role like a lid of the melt of indium, and it becomes difficult for the indium melt to be directly deposited on the substrate, but it is possible to obtain a scintillator plate to which indium ions are added. I understood. This is because the indium melt is in contact with the scintillator material in the step of depositing the melt of the scintillator material, so that indium ions are supplied from the indium melt to the scintillator material melt through the interface between the two melts. it is conceivable that.

  Hereinafter, the scintillator plate of the present embodiment and a method for manufacturing a radiation detector using the scintillator plate will be described more specifically.

(Manufacturing method of scintillator plate)
In the present embodiment, a method for manufacturing a scintillator plate using a vacuum heating deposition method will be described. FIG. 1 shows a schematic diagram of a vapor deposition apparatus 10. The vapor deposition apparatus 10 includes a vacuum chamber 11, a container 12 that evaporates the vapor deposition material and injects the vapor deposition material evaporated onto the base 13, and an exhaust port 14 for evacuating the inside of the vacuum chamber. A surface of the surface of the base 13 on which the scintillator material is deposited is called a deposition surface. The vapor deposition surface is disposed to face the container 12.

  In the present specification, for the purpose of explanation, one or more kinds of materials that do not contain indium element among the vapor deposition materials deposited on the substrate 13 will be described as a scintillator material. Moreover, all the materials deposited on the base | substrate 13 are only described from the following as a vapor deposition material.

  The method for manufacturing a scintillator plate includes the following steps (1) to (3).

  (1) A step of arranging the melt of the scintillator material and the indium melt separated from the melt of the scintillator material in the container so as to be in contact with each other (hereinafter sometimes referred to as a first step). ).

  (2) A step of arranging the container and the base so that the melt of the scintillator material placed in the container is placed between the indium melt and the base (hereinafter, referred to as a second step). ).

(3) A step of depositing the melt of the scintillator material disposed between the indium melt and the base on the base (hereinafter, sometimes referred to as a third step).
Hereinafter, each step will be described.

(1) About the 1st process This process can be performed by putting scintillator material (solid) and indium (solid) in one container 12, and heating this container 12. Specific methods include a resistance heating method and a crucible heating method in which a vapor deposition material is put in a heatable container and heated together, or an electron beam heating method in which the vapor deposition material placed in the container is directly heated by an electron beam. It is done. Although it describes concretely below using a resistance heating method, as embodiment of this invention, it does not restrict to this.

The resistance heating method uses a mechanism in which the container 12 is heated by passing an electric current through the container 12, the temperature of the vapor deposition material in contact with the container 12 is increased, and the vapor deposition material is sublimated or evaporated. As the container 12, a box-shaped, cylindrical, or boat-shaped container having an opening made of a metal such as tungsten or tantalum is used. The shape of the container 12 is not limited in the embodiment of the present invention, and may be improved as appropriate. The shape of the container 12 is particularly limited if the indium melt and the scintillator material melt are separated without mixing and are kept in contact with each other so that both melts do not spill. Not. Further, the size of the container 12 and the size and shape of the opening can also be appropriately set according to the size and film thickness of the substrate to be deposited.
In addition, when adding another material, you may prepare and use the container for vapor-depositing the material separately.

Further, instead of heating the scintillator material (solid) and indium (solid) in one container, this step can be performed by arranging the scintillator material melt and the indium melt in one container. good. Since the melt of the scintillator material and the indium melt are not mixed, they are separated by the difference in density (specific gravity) in the melt state.
The indium melt may contain an element other than indium, but 95 wt% or more is preferably an indium element.

  In addition, the mixing ratio of the scintillator material and indium is not particularly limited, and the amount of the scintillator material melt and the indium melt is not deficient during the vapor deposition (the vapor deposition is completed before the total amount is released from the vessel). What is necessary is just to arrange.

(2) About 2nd process This process can be performed by arrange | positioning a base | substrate in the injection | emission direction of the vapor deposition material of the container by which the melt of the scintillator material and the indium melt were arrange | positioned, for example. You may perform this process by arrange | positioning the base | substrate previously and arrange | positioning the container 12 in which the melt of the scintillator material and the indium melt are arrange | positioned. Moreover, this process can also be performed before a 1st process. In that case, the base 13 and the container 12 may be disposed so that the melt of the scintillator material is disposed between the indium melt and the substrate in the first step. Specifically, when the density of the indium melt is larger than the density of the scintillator material melt, the base 13 and the container 12 in which the scintillator material (solid) and indium (solid) are placed are replaced with the container 12. What is necessary is just to arrange | position in a vacuum chamber so that may become a vertically downward side. If the first step is performed in such a manner, the indium melt 15 is disposed vertically below the scintillator material melt 16, so that the scintillator material melt 16 is interposed between the indium melt 15 and the substrate 13. Is placed.

  It is preferable to select the scintillator material so that the density of the indium melt is larger than the density of the melt of the scintillator material. When the density of the indium melt is higher than the density of the melt of the scintillator material, the layer of the indium melt exists vertically below the melt layer of the scintillator material. Generally, since the injection port of the container 12 is present vertically above the vapor deposition material, this step can be performed if the substrate is disposed vertically above the container. In addition, if the density of the indium melt is higher and the injection port of the container is arranged vertically above the vapor deposition material, the indium melt is not exposed to the space in the vacuum chamber due to the presence of the melt of the scintillator material. , Do not touch the space directly. Therefore, it is possible to make it difficult for indium atoms or clusters to be directly deposited from the indium melt toward the substrate. Since indium atoms and indium clusters are difficult to function as emission centers as they are, loss of indium melt occurs when they are directly deposited on the substrate. Depending on the shape of the container, even if the density of the indium melt is higher than the density of the scintillator material melt, a part of the indium melt may be exposed to the space in the vacuum chamber. In that case, it is preferable to select a scintillator material in which the vapor pressure of indium is smaller than the vapor pressure of the scintillator material. Note that an alkali metal halide (a compound of at least one of Cs and Rb and at least one of F, Cl, Br, and I) known as a scintillator material has a density lower than that of the indium melt. Therefore, this step can be performed by using a container having an injection port vertically above the vapor deposition material and arranging the substrate vertically above.

  (3) About the third step.

  In this step, vapor deposition is performed in a state where the container and the substrate in which the vapor deposition material is disposed are disposed so that the melt of the scintillator material disposed in the container 12 is disposed between the indium melt and the substrate. It can be done by doing.

  Before vapor deposition, it is preferable that the vacuum chamber is once evacuated to at least 0.01 Pa or less by evacuating from the exhaust port 14 with a vacuum pump or the like. In FIG. 1, the container 12 is arranged vertically below the base body 13, but in the container, the scintillator material melt is on the base body side, that is, on the emission port side, and at a position where the vapor deposition material is ejected. The arrangement of the container and the substrate is not particularly limited as long as the substrate is arranged. If the melt of the scintillator material can be deposited, the deposition temperature is not particularly limited. For example, the deposition temperature of general cesium iodide is 500 ° C. or more and 900 ° C. or less, and thus the deposition temperature when cesium iodide is used as the scintillator material. Is preferably within this range. The columnar crystal of cesium iodide is known as a scintillator having waveguide properties, and may be manufactured using oblique deposition. However, this embodiment is applied to oblique deposition, and the columnar crystal of cesium iodide is used. A scintillator plate may be manufactured by vapor-depositing the material on a substrate.

  By this step, a scintillator plate to which indium ions are added can be obtained. As described above, this is considered to be because indium ions are supplied to the melt of the scintillator material in this step.

  After the vapor deposition, the container was cooled and the solidified vapor deposition material was taken out, and the taken out solid was separated into an indium lump and a colorless polycrystal. The former indium was agglomerated and could be taken out together, and the weight loss was negligible. The latter colorless polycrystal showed light emission by X-ray irradiation, and it was confirmed that this light emission was due to indium ions present in the cesium iodide crystal. From the above, it can be inferred that the melt of the scintillator material and indium is separated into two layers in the vessel during vapor deposition, and a small amount of the indium melt enters the scintillator material melt. It can be considered that indium ions are supplied.

  According to this consideration, even if the concentration of indium ions contained in the scintillator material melt is decreased, indium ions are supplied if the indium melt is in contact with the scintillator material melt. In addition, indium ions evaporate from the scintillator melt layer with the scintillator material molecules. Therefore, the deposition material can be deposited while maintaining the concentration of indium ions, and an indium activated scintillator layer with a small deviation in concentration distribution of indium ions in the layer thickness direction can be deposited on the substrate 13. Therefore, it is preferable that the melt 16 of the scintillator material and the indium melt 15 are in contact during the vapor deposition.

(Method for adjusting the concentration of indium)
The concentration of indium (including indium ions) in the scintillator layer can be adjusted by adjusting the amount of indium that dissolves into the melt of the scintillator material.

  There are two methods for adjusting the amount of indium that dissolves into the melt of the scintillator material.

  The first method is a method of adjusting the temperature of the melt 16 of scintillator material. For example, the concentration of indium in the melt layer of the scintillator material can be increased by increasing the temperature of the melt layer in contact with the container 12. To support this, the following study was conducted. Quartz ampules were filled with cesium iodide and a small amount of indium metal, sealed in a vacuum, melted in an electric furnace, and then gradually cooled and solidified to evaluate luminescence. At this time, five types of crystal samples having a melting temperature of 700 to 900 ° C. and increments of 50 ° C. were prepared for evaluation. As a result, when the melting temperature was raised, the intensity of light emission due to indium increased. Although the correlation between the emission intensity and the indium concentration is not clearly understood, the correlation between the concentration of the additive element and the emission intensity is generally positive as long as no indium iodide precipitates and the scintillator functions. It is considered to be. Therefore, it is considered that the concentration of indium element can be increased by increasing the melting temperature, that is, the temperature of the container 12, and the concentration can be decreased by decreasing the melting temperature. The evaluation results of the five types of crystal samples were all good emission intensity, and it was found that good emission intensity can be obtained if the temperature of the melt of the scintillator material is not less than 700 degrees and not more than 900 degrees. It was.

  The second method is a method of increasing or decreasing the contact area between the indium melt and the melt of the scintillator material. As described above, since indium dissolves through the interface between both melts, if the area of both interfaces is large, it can be considered that more indium is dissolved in accordance with the area. As a result, the indium concentration of the scintillator layer can be increased. If the surface area of the indium melt is increased by increasing the volume of the indium melt, the contact area also increases. However, if there is a limit to increase the contact area depending on the shape of the vapor deposition container, the shape of the container may be improved as appropriate. For example, if the bottom area of the container is increased, the contact area can be increased. In addition, when the indium melts, the surface area is increased by allowing the indium melt to be finely pulverized by dividing the inside of the container into barrier ribs so that the indium melt does not gather near one melt. Can do. Conversely, if the contact area is reduced, the indium concentration can be lowered.

(Production method of radiation detector)
A radiation detector provided with the above-mentioned scintillator plate can be manufactured by arranging and fixing the above-mentioned scintillator plate on the detection surface of the photodetector. At this time, it arrange | positions so that the scintillator layer side of a scintillator plate may become a photodetector side. Further, the scintillator layer and the detection surface of the photodetector do not need to be in direct contact, and for example, a protective layer may be disposed between the scintillator layer and the detection surface.

  In FIG. 3, the cross-sectional schematic diagram of the radiation detector 30 of this embodiment is shown. The above-mentioned scintillator plate 31 is arranged on the photodetector 33 having a plurality of pixels 35 arranged in an array on the substrate 34 so that the scintillator layer 32 is on the photodetector 33 side.

  In this example, a specific example in which a scintillator plate is manufactured using the above-described embodiment will be described. In addition, the result of the light emission evaluation of the manufactured scintillator plate and the measurement result of the indium concentration will be described. As the scintillator material, cesium iodide was used.

As vapor deposition materials, 20 g of cesium iodide powder and 10 g of indium metal particles were weighed and filled in one tantalum heating vapor deposition container. This vapor deposition container has a cylindrical shape with a volume of approximately 12.6 cm ³ , and a slit (injection port) having a length of 2 cm and a width of 0.2 cm is provided on the side surface along the axis of the cylinder. The vapor deposition material is ejected from the slit toward the substrate. A silicon substrate was prepared as a substrate. The vapor deposition container was placed on the heating means in the vacuum chamber, and the substrate was placed vertically above the vapor deposition container in the vacuum chamber so as to face the slit of the vapor deposition container (second step).

  Here, a shutter is provided between the slit and the substrate, and a mechanism capable of external operation is provided so that the deposition of the vapor deposition material can be arbitrarily started or terminated. The inside of the vacuum chamber was evacuated until the atmospheric pressure became approximately 0.01 Pa or less. The substrate rotation was set at a speed of 40 rotations per minute (40 rpm). In order to heat the vapor deposition container, about 50 A DC current was passed through the heating means for about 30 minutes using an external power supply to maintain the heating. This is heating for the purpose of desorbing water molecules or carbonic acid adhering to the powder surface of the vapor deposition material. Thereafter, the current value flowing through the heating means was increased to 75 A at a rate of 5 A / 3 minutes. This state was maintained for 5 minutes (first step), and the above-described shutter was removed from between the slit and the substrate, thereby starting deposition of a melt of scintillator material containing indium ions on the substrate (third process). Process). At this time, it was about 730 degreeC when the temperature of the vapor deposition container was measured with the radiation thermometer. After the deposition of the scintillator material by vapor deposition was continued for 50 minutes, the vapor deposition was terminated by holding the shutter over the front surface of the substrate. After the vapor deposition vessel and the substrate are cooled to approximately room temperature, the vacuum chamber is opened to the atmosphere, the substrate on which the scintillator material containing indium ions is deposited (that is, the scintillator plate) is taken out, and the thickness of the scintillator layer is measured. It was 230 μm. Using this scintillator plate, the emission spectrum and the concentration of indium were measured as follows.

An emission spectrum by X-ray excitation was measured. The measurement method will be specifically described.
As the quality of incident X-rays for measurement, the quality of X-rays generated by applying a tube voltage of 60 kV and a tube current of 0.1 mA to a tungsten target was filtered with a 3 mm thick aluminum filter. It was. The scintillator layer obtained in the present embodiment is placed in an integrating sphere of φ100 mm, and incident X-rays are introduced from a port facing the scintillator layer to irradiate the scintillator surface. Here, a lead plate having an opening of φ15 mm is provided at the entrance port for incident X-rays, and the spot diameter of X-rays irradiated on the scintillator surface is reduced to about φ15 mm. This is an operation for removing the influence of the scattered X-rays on the measurement system. By guiding the light in the sphere to the spectroscope using an optical fiber installed at a port different from the above, an emission spectrum by X-ray excitation of the scintillator layer in the integrating sphere can be obtained as a result. However, it is assumed that the above measurement needs to be performed in a dark room, and that the light receiving sensitivity at each wavelength of the integrating sphere, optical fiber, and spectrometer is calibrated.

  FIG. 2 shows an emission spectrum obtained by this example. Light emission over a wide wavelength range centered around the wavelength of 550 nm was confirmed. The cesium iodide crystal exhibits strong light emission centered around a wavelength of 300 nm, and this light emission is known to be light emitted by bound excitons. Indium-activated cesium iodide crystals exhibit broadband emission centering around 550 nm, and this emission is known to be due to monovalent indium present in the cesium iodide crystal. . From the above, the light emission of the scintillator layer obtained in this example can be attributed to the indium activated cesium iodide crystal from the viewpoint of the emission peak wavelength and the emission spectrum shape. Therefore, it was confirmed that the scintillator layer produced in this example was an indium activated scintillator layer that emits light by X-ray excitation.

  The concentration of indium was measured using an X-ray Fluorescence analysis (XRF: X-ray Fluorescence analysis). The measurement method will be specifically described. A collimator made of lead was disposed between the scintillator layer and the incident X-ray source in order to irradiate the scintillator layer obtained in this example with incident X-rays in a circular shape of φ30 mm. The elements and their abundance were quantified by spectroscopically detecting fluorescent X-rays emitted from the scintillator with a wavelength dispersive X-ray spectrometer. In the present invention and this specification, the indium concentration is defined as a value obtained by calculating a ratio of the number of atoms of indium element (including ions) to the number of all detected atoms. The unit is atm%. When this analysis method is used, the indium concentration corresponding to a depth of several μm or several tens of μm from the surface is averaged and obtained.

  Using the analysis method described above, the concentration of indium was quantified on the surface of the scintillator layer obtained in this example, that is, the last part of the deposition, and on the surface where the scintillator layer was peeled off from the substrate, that is, the part at the beginning of the deposition. did. The indium concentrations on the scintillator layer surface and the back surface were 0.015 atm% and 0.014 atm%, respectively, and it was confirmed that the difference in concentration between the front and back surfaces was small.

  Moreover, when the vapor deposition container was taken out, it was confirmed that the cesium iodide solidified body and the indium metal lump were separated. From the above, both the cesium iodide raw material and the indium metal raw material are not short on the way, and the deposited film has a substantially constant indium concentration from the beginning to the end of the deposition, that is, indium in the layer thickness direction. It was inferred that the concentration distribution was small. In general, the preferable concentration of the emission center is about 0.001 atm% or more and 1.0 atm% or less, more preferably 0.001 atm% or more and 0.5 atm% or less, and further preferably 0. 0.01 atm% or more and 0.5 atm% or less. It was confirmed that the concentration of the emission center (indium) in the scintillator layer of this example was within this range.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.

11 Vacuum chamber 12 Container 13 Base 14 Exhaust port

Claims (8)

Arranging the scintillator material melt and the indium melt separated from the scintillator material in a container so as to be in contact with each other;
Disposing the container and the substrate such that a melt of the scintillator material disposed in the container is disposed between the indium melt and the substrate;
Depositing a melt of the scintillator material disposed between the indium melt and the base on the base. A method for manufacturing a scintillator plate, comprising: The density of the melt of the scintillator material is
The method of manufacturing a scintillator plate according to claim 1, wherein the density of the indium melt is smaller than the density of the indium melt.   The method for manufacturing a scintillator plate according to claim 1 or 2, wherein the indium melt is disposed at least in a part vertically below the scintillator material.   4. The scintillator according to claim 1, wherein the scintillator material is an alkali metal halide having at least one of Cs and Rb and at least one of F, C, Br, and I. 5. Plate manufacturing method.   The scintillator plate manufacturing method according to claim 4, wherein the scintillator material is cesium iodide.   In the step of depositing, a melt of the scintillator material is disposed between the indium melt and a space in the chamber of the vapor deposition apparatus, and the indium melt is exposed to a space in the chamber of the vapor deposition apparatus. The method for manufacturing a scintillator plate according to any one of claims 1 to 5, wherein the scintillator plate is not provided. In the step of depositing,
The method of manufacturing a scintillator plate according to any one of claims 1 to 6, wherein a temperature of the melt of the scintillator material is not less than 700 degrees and not more than 900 degrees. Arranging the scintillator material melt and the indium melt separated from the scintillator material in a container so as to be in contact with each other;
Disposing the container and the substrate such that a melt of the scintillator material disposed in the container is disposed between the indium melt and the substrate;
Depositing a melt of the scintillator material disposed between the indium melt and the substrate on the substrate;
A scintillator layer of a scintillator plate in which the scintillator material is deposited on the substrate, and a step of fixing the scintillator layer on a photodetector.

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