Phosphor, its manufacturing method, and alpha ray detector

Abstract

To provide a fluorescent body which enables discriminative measurement of α-rays, a manufacturing method therefor, and an α-ray detector.SOLUTION: A fluorescent body of the present invention is used for radiation detection and comprises a scintillator layer on a front side and a substrate layer on a rear side in an incident direction of radiation. The scintillator layer has a thickness of 5 to 30 μm, inclusive, and is transmissive to visible light generated by irradiation of α-rays, and the substrate layer is made of a material different from that of the scintillator layer and does not emit light when irradiated with radiation.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a phosphor, a method for producing the same, and an α-ray detector. [Background technology]

[0002] In nuclear power plants and other facilities, radiation emitted from waste containing radioactive materials and from radioactively contaminated equipment can be divided into three types: alpha rays, beta rays, and gamma rays. In order to evaluate environmental pollution caused by these types of radiation, radiation detectors equipped with scintillators are required. Scintillators are a group of materials that emit light mainly in the visible light range when exposed to radiation, and are also used in photoelectric conversion elements such as photomultiplier tubes.

[0003] Since α-rays have a strong interaction with materials, when they enter a scintillator layer having a thickness of several microns to several tens of microns, their progress is completely blocked inside the scintillator layer. On the other hand, since γ-rays have a high penetrating power, they cannot be completely blocked even by a scintillator layer having a thickness of about several microns, and the thickness required for blocking is about several tens of microns to several hundreds of microns. Therefore, for example, when α-rays and γ-rays simultaneously enter a scintillator layer having a thickness of about several hundreds of microns, both are blocked within the scintillator layer, and light emission due to the radiation types of both α-rays and γ-rays occurs.

[0004] It is difficult to distinguish and measure α-rays and γ-rays using a single survey meter for radiation generated from objects of unknown nuclide, such as radioactive waste. Therefore, when the radiation incident on the scintillator layer contains both α-rays and γ-rays, it is necessary to detect the luminescence originating from α-rays and the luminescence originating from γ-rays using separate survey meters. However, for example, in a radiation contaminated site where an emergency is required, using multiple types of survey meters is technically difficult and an economic burden. Therefore, there is a demand for a technology that makes it possible to identify and distinguish the type of radiation as α-rays using a single survey meter. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2016-164210 A [Patent Document 2] JP 2019-119798 A [Non-patent literature]

[0006] [Non-Patent Document 1] S.Witkiewicz-Lukaszek, V.Gorbenko, T.Zorenko, O.Sidletskiy, P.Arhipov, A.Fedorov, JAMares, R.Kucerkova, M.Nikl, and Y.Zorenko: CrystEngComm 22 (2020) 3713-3724. Summary of the Invention [Problem to be solved by the invention]

[0007] As a scintillator layer for detecting radiation, a single crystal having a homogeneous structure is used in order to obtain high luminous efficiency (Patent Documents 1 and 2). The single crystal is obtained by processing a single crystal ingot formed by a melt solidification method to a specified thickness, and it is difficult to make the thickness of the obtained single crystal 50 μm or less.

[0008] By using the liquid phase epitaxy method, it is possible to synthesize a scintillator layer made of a single crystal with a thickness of 50 μm or less. However, since it is difficult to avoid the inclusion of impurity elements during the synthesis process, a single crystal formed with a thickness of 50 μm or less does not emit a sufficient amount of light due to the influence of the impurity elements.

[0009] Using common thin film deposition methods such as sputtering, it is difficult to form single crystals with a thickness of 5 μm or more. Single crystals formed using this method are too thin to block the progression of alpha rays, and sufficient light emission from alpha rays cannot be obtained.

[0010] In Non-Patent Document 1, a two-layer structure is used to discriminate alpha rays by discriminating alpha rays on the front side and gamma rays on the rear side when viewed from the radiation incidence direction, but the photodetector in this case is limited to measuring single photons using photomultiplier tubes, photodiodes, etc., and the spatial resolution is limited to about 1 mm or more. Furthermore, there are problems such as the circuitry at the rear of the photodetector becoming complicated in order to discriminate gamma rays, making analysis complicated.

[0011] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a phosphor that enables discriminative measurement of α-rays, a method for producing the same, and an α-ray detector. [Means for solving the problem]

[0012] In order to solve the above problems, the present invention employs the following means.

[0013] (1) A phosphor according to one aspect of the present invention is a phosphor used for radiation detection, characterized in that it comprises a scintillator layer and a substrate layer as defined below. That is, it comprises a scintillator layer having a thickness of 5 μm or more and 30 μm or less and being transparent to visible light generated by irradiation with α-rays. It also comprises a substrate layer, different from the scintillator layer, which is not accompanied by light emission due to radiation, downstream of the scintillator layer upon incidence of radiation.

[0014] (2) In the phosphor described in (1) above, it is preferable that the scintillator layer is made of a material having an effective atomic number of 10 or more and 75 or less, and has a thickness of 5 μm or more and 30 μm or less.

[0015] (3) In the phosphor according to (1) or (2) above, it is preferable that the scintillator layer is made of a plurality of phases including a main phase of a single crystal structure, and the main phase occupies 50% or more of the total volume.

[0016] (4) In the phosphor according to any one of (1) to (3) above, the scintillator layer preferably contains an activator element in a ratio of 0.01 mol % to 20 mol %.

[0017] (5) In the phosphor described in any one of (1) to (4) above, it is preferable that the main phase of the scintillator layer has one or a combination of two or more of a garnet structure, a bixbyite structure, a perovskite structure, a cuspidine structure, an orthosilicate structure, a pyrosilicate structure, and a pyrochlore structure.

[0018] (6) An α-ray detector according to one embodiment of the present invention includes a position-sensitive detector that detects only the visible light, disposed downstream of the phosphor described in any one of (1) to (5) above with respect to the incidence of radiation, and discriminates only the α-rays from among two or more types of radiation including α-rays, without discriminating the radiation on an event-by-event basis. Examples of the position-sensitive detector include, but are not limited to, a CCD or CMOS sensor.

[0019] (7) A method for producing a phosphor according to one embodiment of the present invention is a method for producing a phosphor as described in any one of (1) to (6) above, in which the scintillator layer is formed on one surface of the substrate layer using a laser CVD method. Effect of the Invention

[0020] The phosphor of the present invention has a scintillator layer having a thickness of 5 μm to 30 μm, and is capable of transmitting highly penetrating radiation such as gamma rays while blocking the progress of only alpha rays within the scintillator layer. Therefore, only visible light originating from alpha rays is emitted within the scintillator layer when irradiated with radiation. Since the scintillator layer is transparent to this visible light, it can be detected from outside the phosphor, and discrimination measurement of alpha rays can be performed based on the detection results without discriminating between radiation such as gamma rays. [Brief description of the drawings]

[0021] [Figure 1] FIG. 1 is a cross-sectional view that illustrates a schematic configuration of a laser CVD apparatus used for producing a phosphor of the present invention. [Diagram 2] 1 is an example of a conceptual diagram of an alpha ray detector. [Diagram 3] 1(a) and 1(b) are SEM images of the cross section and the surface of the phosphor of Example 1. [Figure 4] 2 is a graph showing the light emission characteristics of the phosphor of Example 1. [Diagram 5] 1 is a graph showing the emission characteristics of phosphors of Example 1 and Comparative Example 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] The phosphor according to the embodiment of the present invention and its manufacturing method will be described in detail below with reference to the drawings. Note that the drawings used in the following description may show characteristic parts in an enlarged scale for the sake of convenience in order to make the characteristics easier to understand, and the dimensional ratios of each component may not necessarily be the same as in reality. In addition, the materials, dimensions, etc. exemplified in the following description are merely examples, and the present invention is not limited to them, and can be appropriately modified and implemented within the scope that does not change the gist of the present invention.

[0023] First Embodiment (Phosphor) The phosphor according to the first embodiment of the present invention is a phosphor used for radiation detection, and includes a scintillator layer made of a substance that emits light mainly in the visible light range when irradiated with radiation. The scintillator layer has a thickness of 5 μm to 30 μm, which is suitable for absorbing α-rays and transmitting high-energy radiation such as γ-rays.

[0024] If the thickness of the scintillator layer is less than 5 μm, a sufficient amount of light emission may not be obtained, and since the irradiated α-rays pass through the scintillator layer, the light emission due to α-rays, which is necessary for discriminating α-rays, does not occur. Also, if the thickness of the scintillator layer exceeds 30 μm, not only α-rays but also gamma rays are absorbed by the scintillator layer, so light emission due to gamma rays occurs in addition to light emission due to α-rays.

[0025] The absorptivity of the irradiated radiation is affected by the effective atomic number of the constituent material. Therefore, from the viewpoint of increasing the absorptivity, for example, when the scintillator layer is made of a material with an effective atomic number of 10 to 50, it is preferable that the layer has a thickness of 8 μm to 30 μm. When the scintillator layer is made of a material with an effective atomic number of 50 to 75, it is preferable that the layer has a thickness of 5 μm to 25 μm.

[0026] The scintillator layer has a transmittance of 10% to 90% to the extent that visible light generated by irradiation with α-rays can be detected by a predetermined detection device. From the viewpoint of increasing the transmittance of visible light, it is preferable that the layer has an orientation degree of 50% or more of that of a single crystal structure, and it is most preferable that the layer has a single crystal structure. As long as the transmittance of visible light is not too low, the scintillator layer may have a structure consisting of multiple phases including a main phase of a single crystal structure. However, it is preferable that the main phase of the single crystal occupies 50% or more of the total volume. The scintillator layer preferably has one or a combination of two or more of the following structures: garnet structure, bixbyite structure, perovskite structure, cuspidine structure, orthosilicate structure, pyrosilicate structure, and pyrochlore structure.

[0027] The scintillator layer is A 3 B 5 O 12 The garnet structure represented by the formula 2 O 3 In addition, the scintillator layer may simultaneously have different crystal phases containing an oxide represented by A 2 O 3 The bixbyite structure, represented by ABO 3 The perovskite structure represented by A 4 B 2 O 9In these cases, A may be, for example, one or a combination of two or more of Gd, Sc, Y, Tb, Dy, Ho, Er, Tm, Yb, and Lu, and B may be, for example, one or a combination of two or more of Al and Ga.

[0028] The scintillator layer is A 2 O 3 The bixbyite structure represented by the formula 2 O 3 , A 3 B 5 O 12 , A 4 B 2 O 9 In these cases, A may be, for example, one or a combination of two or more of Gd, Sc, Y, Tb, Dy, Ho, Er, Tm, Yb, and Lu, and B may be, for example, one or a combination of two or more of Al and Ga.

[0029] The scintillator layer is A 2 BO 5 The orthosilicate structure represented by the formula 2 O 3 In this case, A can be, for example, one or a combination of two or more of Gd, Y, Yb, and Lu, and B can be, for example, Si.

[0030] The scintillator layer is ABO 3 Preferably, the perovskite structure is represented by the double phase BO 2 In the case of the perovskite structure, A may be, for example, one or a combination of two or more of Ca, Sr, Ba, and Pb, and B may be, for example, one or a combination of two or more of Ti, Zr, and Hf.

[0031] The scintillator layer is A 2 B 2 O 7 Pyrosilicate or pyrochlore structure represented by the formula: 2 In the case of the pyrosilicate structure, A may be one or a combination of two or more of Gd, Y, Yb, and Lu, and B may be, for example, Si. In the case of the pyrochlore structure, A may be one or a combination of two or more of Gd, Sc, Y, Tb, Dy, Ho, Er, Tm, Yb, and Lu, and B may be one or a combination of two or more of Ti, Zr, and Hf.

[0032] The scintillator layer preferably contains an activator element in a ratio of 0.01 mol % to 20 mol %. Examples of the activator element include Ce. 3+ ,Pr 3+ , Nd 3+ , Sm 3+ ,EU 3+ , Tb 3+ , Dy 3+ , Ho 3+ , Er 3+ , Tm 3+ , Yb 3+ ,EU 2+ One or a combination of two or more of the above may be used.

[0033] The scintillator layer is made of Mg to adjust the charge balance and prevent crystal defects. 2+ , Ca 2+ , Sr 2+ , B.A. 2+ , Li + ,Na + , K + In addition, elements other than these may be added for the same purpose.

[0034] (Method of manufacturing phosphor) 1 is a cross-sectional view showing a schematic configuration example of a laser CVD apparatus 100 used for producing a phosphor according to this embodiment. The laser CVD apparatus 100 is mainly composed of a chamber 101, a substrate support section 102 that supports a substrate 10 in the chamber 101, a laser light irradiation section 103 that irradiates the substrate 10 with a laser light, and a source gas supply section 104 that supplies a source gas into the chamber 101.

[0035] The substrate support section 102 is mainly composed of a stage 102A on which the substrate 10 is placed, and a thermocouple 102B that is attached to the stage 102A and monitors the temperature of the substrate 10.

[0036] The laser irradiated by the laser light irradiating section 103 may be, for example, a carbon dioxide laser, a semiconductor laser, or a solid-state laser.

[0037] The raw material gas supply unit 104 is mainly composed of heater chambers 104B, 104D, which heat and vaporize the precursor of the phosphor raw material to produce raw material gas, carrier gas (Ar gas) supply sources (supply units) 104A, 104C, a nozzle 104E that introduces the raw material gas and carrier gas into the chamber 101, an oxygen gas supply source (supply unit) 104F, and a nozzle 104G that introduces the supplied oxygen gas into the chamber 101.

[0038] For example, in the case of producing a phosphor made of LuAG, one heater chamber 104B is filled with lutetium dispivaloylmethanato (Lu(dpm) 3 ) and the other heater chamber 104D serves as a source of aluminum trisacetylacetonate (Al(acac) 3 The number of heater chambers may be increased or decreased depending on the number of raw materials required.

[0039] Carrier gas supply sources 104A and 104C are connected to heater chambers 104B and 104D, respectively, and are configured so that the supplied carrier gas passes through heater chambers 104B and 104D and transports the source gas vaporized in heater chambers 104B and 104D into chamber 101. Carrier gas supply sources 104A and 104C and oxygen gas supply source 104F each include a mass flow controller that adjusts the flow rate of the gas supplied.

[0040] The method for producing a phosphor has the following steps. First, the substrate 10 is placed on the stage 102A, and the chamber 101 is evacuated to a pressure suitable for film formation (evacuation step). Next, the laser light irradiating unit 103 is used to irradiate the substrate 10 with laser light L to heat the substrate 10 (substrate heating step). Then, the raw material gas is supplied to the heated substrate 101 together with the carrier gas, thereby forming a phosphor film (phosphor film forming step).

[0041] In the phosphor film forming process, when multiple kinds of raw material gases are supplied, the content ratio (composition ratio) of various raw materials in the phosphor to be formed can be adjusted by adjusting the content ratio. Also, the thickness of the phosphor to be formed can be adjusted by adjusting the time for supplying the raw material gases, i.e., the film formation time.

[0042] As described above, the phosphor of the first embodiment has a scintillator layer having a thickness of 5 μm to 30 μm, and can transmit highly penetrating radiation such as gamma rays while blocking (absorbing) the progress of only alpha rays within the scintillator layer. Therefore, only visible light originating from alpha rays is emitted within the scintillator layer when irradiated with radiation. Since the scintillator layer is transparent to this visible light, it can be detected from outside the phosphor, and discrimination measurement of alpha rays can be performed based on the detection result.

[0043] When a melt solidification method is used to manufacture a phosphor, it is difficult to achieve a thickness of 5 μm or more and 30 μm or less, but this is possible by using the laser CVD method of this embodiment. In addition, when the laser CVD method of this embodiment is used, the problem of the liquid phase method in which impurity elements such as transition metals and alkali metals are mixed in can be avoided, and a high amount of light emission can be achieved without being affected by impurity elements. Even when the phosphor is thin, the amount of light emission necessary for discriminating α rays can be obtained, so it is possible to thin the phosphor to the range of 5 μm or more and 30 μm or less, which allows γ rays to pass through.

[0044] Second Embodiment The phosphor according to the second embodiment of the present invention is a phosphor used for radiation detection, and includes a scintillator layer on the front side in the direction of incidence of radiation, and a substrate layer on the rear side. The substrate layer has a thickness of 5 μm to 20 mm, is made of a material different from that of the scintillator layer, and is transparent to visible light generated in the scintillator layer. The substrate layer is laminated (bonded) to the scintillator layer directly or with an intermediate layer sandwiched therebetween. The configuration of the scintillator layer is the same as that of the phosphor of the first embodiment, and discriminative measurement of α-rays can be performed.

[0045] The phosphor of this embodiment is obtained by using the above-mentioned substrate layer as a base material and forming a scintillator layer on one side of the substrate layer by using a laser CVD method in the same manner as in the first embodiment. The order of lamination of the two layers is not limited, and the substrate layer may be prepared first and the scintillator layer may be crystal-grown thereon, or the scintillator layer may be prepared first and the substrate layer may be crystal-grown thereon. In either case, from the viewpoint of assisting crystal growth, it is preferable that the scintillator layer and the substrate layer are made of materials having similar crystal structures.

[0046] In this embodiment, it is assumed that there are two scintillator layers with different thicknesses, but the number of scintillator layers is not limited, and three or more scintillator layers may be provided in order to discriminate radiation other than alpha rays and gamma rays.

[0047] In the phosphor of this embodiment, the scintillator layer having a thickness of 5 μm to 30 μm absorbs only α-rays, and the substrate layer having a thickness of 5 μm to 20 mm absorbs radiation transmitted through the scintillator layer. For example, when the substrate layer has a thickness of 50 μm to 20 mm, it can absorb γ-rays.

[0048] FIG. 2 is a diagram showing a schematic configuration of an α-ray detector 200 to which the phosphor of this embodiment is applied. The α-ray detector 200 is composed of a phosphor having a scintillator layer 201 on the front side in the direction of incidence of radiation and a substrate layer 202 on the rear side, and a position-sensitive photodetector 203 for detecting only visible light arranged on the rear side of the phosphor. The position-sensitive detector is not particularly limited, and examples thereof include image sensors such as CCD and CMOS sensors composed of multiple pixels. Visible light generated in the scintillator layer 201 by irradiation with α-rays passes through the substrate layer 202 and reaches the position-sensitive photodetector 203. Radiation other than α-rays, such as gamma rays, passes through the scintillator layer 201 and is absorbed by the substrate layer 202 or passes through the substrate layer 202. Here, the region and shape in which light is emitted in 201 for each radiation are characteristic. For example, since alpha rays have a range of several micrometers, the range in which light is emitted is roughly symmetrical with respect to the point of incidence of the alpha rays at 201, and is an area of ​​several micrometers. On the other hand, the signal generated when gamma rays are incident on 203 becomes pixel noise. Therefore, when multiple events are measured simultaneously, alpha rays can be discriminated by 203.

[0049] The combination of the phosphor and the position sensitive photodetector is configured, for example, as shown in Fig. 2, and when the magnitude of the signal from the position sensitive photodetector 203 is equal to or greater than a certain level, it is discriminated as a signal in the scintillator layer 201. Also, α-rays and noise may be discriminated from the imaging results based on their spread. Note that the combination method and analysis method of the position sensitive photodetector 203 are not limited to this. EXAMPLES

[0050] The effects of the present invention will be more clearly understood by the following examples. Note that the present invention is not limited to the following examples, and can be modified as appropriate without departing from the spirit and scope of the present invention.

[0051] Example 1 Using the above-mentioned manufacturing method for phosphors, LuAG (Lu 3 Al 5 O 12 ) as the main phase, and Ce as the activation element. 3+ A scintillator layer containing 9.0 mol% of YAG was formed on one side of the substrate. The thickness of the scintillator layer was 5.2 μm. The effective atomic number was 62.9. 3 Al 5 O 12 The main manufacturing conditions for the scintillator layer were set as follows: Laser power density: 79W / cm 2 Ar gas flow rate: 100sccm Oxygen gas flow rate: 100sccm Raw material vaporization temperature: 190~270℃ Film forming temperature: 970℃ Film forming pressure: 200Pa Deposition speed: 62μm / h

[0052] Comparative Example 1 Commonly known as scintillator crystals, Gd 3 Al 2 Ga 3 O 12 The main phase is (GAGG), and Ce is used as an activation element. 3+ The scintillator layer was formed by melting and solidifying the material. The thickness of the scintillator layer was about 1 mm.

[0053] 3(a) and (b) are SEM images of the cross section and surface of the phosphor formed in Example 1. It can be seen that a film with a uniform thickness of about 5 μm is formed as the scintillator layer. In addition, since the surface is uniform, it can be seen that the scintillator layer has a single crystal structure.

[0054] The scintillator layer of Example 1 was irradiated with 5.5 MeV α-rays, and the light emitted from the scintillator layer to the outside was measured to examine the emission spectrum. FIG. 4 is a graph showing the measurement results. The horizontal axis of the graph indicates the emission wavelength [nm], and the vertical axis of the graph indicates the emission intensity. Since the emission spectrum has a peak near a wavelength of 500 nm in the visible light range, it is believed that Ce 3+ It is clear that luminescence originating from ions is occurring, and that the irradiated alpha rays are being converted into visible light.

[0055] The scintillator layers of Example 1 and Comparative Example 1 were irradiated with radiation including α-rays and γ-rays, and measurements were performed to examine the pulse height spectrum of the visible light converted in each scintillator layer. Figure 5 is a graph showing the measurement results. The horizontal axis of the graph indicates the digital channel value [ch] corresponding to the amount of light emitted, and the vertical axis of the graph indicates the light emission intensity.

[0056] The pulse height spectrum 401 of Comparative Example 1 has both a peak in an energy region of 200 ch or less, which indicates a response to gamma rays, and a peak in an energy region of 1000 to 1200 ch, which indicates a response to alpha rays. Therefore, in the scintillator layer of Comparative Example 1, light emission originating from both alpha rays and gamma rays occurs, and it is found that it is difficult to discriminate and measure alpha rays from this light emission.

[0057] On the other hand, the pulse height spectrum 402 of Example 1 does not have a peak in the energy region of 200 ch or less, and has a peak only in the energy region of 1000 to 1200 ch. Therefore, in the scintillator layer of Example 1, the luminescence originating from gamma rays is suppressed and only the luminescence originating from alpha rays is generated, and it is therefore possible to discriminate and measure the alpha rays from this luminescence.

[0058] Example 2 Using the above-mentioned manufacturing method for the phosphor, the main phase is LuAG having a garnet structure, and Ce is used as an activator element. 3+A scintillator layer containing 9.0 mol% of Al was formed on one side of the substrate. The thickness of the scintillator layer was 1.6, 2.1, 4.3, 9.7, and 22·2 μm. 2 O 3 The following structure was used:

[0059] The scintillator layer of Example 2 was irradiated with 5.5 MeV alpha rays, and an image was taken with a CCD camera to measure the intensity. The results are shown in Table 1. The cases where it was determined that a signal was detected are indicated with a circle, and the cases where it was determined that a signal was not detected are indicated with an x. From this, it was found that a sufficient signal was not visible when the thickness was about 5 μm or less.

[0060] [Table 1]

[0061] (Examples 3 to 13) Using the above-mentioned method for producing a phosphor, a Y phosphor having a bixbyite structure was 2 O 3 , Lu with bixbyite structure 2 O 3 , LuAP (LuAlO 3 ) and LuAG with a garnet structure as the main phase, respectively, with Eu as an added element. 3+ , Nd 3+ , Ce 3+ The scintillator layer was formed on one side of the substrate. 2 O 3 -ZrO 2 ), STO(SrTiO 3 ), and YAG.

[0062] The scintillator layers of Examples 3 to 13 were irradiated with 5.5 MeV α-rays, received by a photomultiplier tube, and the photoelectrons were counted. The results are shown in Table 2. The cases where it was determined that a signal was detected are indicated by ◯, and the cases where it was determined that a signal was not detected are indicated by ×. From this, it can be seen that when the material has an effective atomic number of 10 to 50, a signal can be detected at a thickness of 8 μm or more, and when the material has an effective atomic number of 50 to 75, a signal can be detected at a thickness of 5 μm or more. Therefore, it can be seen that the scintillator layer composed of the above-mentioned main phase and activation element can be used for discriminating and measuring α-rays by having the above-mentioned range of additive concentration and film thickness.

[0063] [Table 2] [Explanation of symbols]

[0064] 100 Laser CVD equipment 101...Chamber 102...Base material support part 102A···Stage 102B Thermocouple 103 Laser light irradiation unit 104: Raw material gas supply section 104A: Carrier gas supply source (supply section) 104B: Heater chamber (source of raw material precursor) 104C Carrier gas supply source (supply section) 104D: Heater chamber (source of raw material precursor) 104E: Raw material precursor gas supply nozzle 104F: Oxygen gas source 104G...Oxygen gas supply nozzle L...Laser light 200···α-ray detector 201...Scintillator layer 202...Substrate layer 203...position-sensitive photodetector 204 Alpha rays 205 Gamma rays 206... Illumination

Claims

1. A phosphor for use in radiation detection, comprising: a scintillator layer on a front side and a substrate layer on a rear side in a direction in which radiation is incident; the scintillator layer has a thickness of 5 μm or more and 30 μm or less, has an orientation degree of 50% or more of that in the case of a single crystal structure, and is transparent to visible light generated by irradiation with α-rays; A phosphor, characterized in that the substrate layer is made of a material different from that of the scintillator layer and does not emit light in response to the radiation.

2. 2. The phosphor according to claim 1, wherein the scintillator layer is made of a material having an effective atomic number of 10 to 75 and has a thickness of 5 μm to 30 μm.

3. 3. The phosphor according to claim 1, wherein the scintillator layer is made of a plurality of phases including a main phase of a single crystal structure, and the main phase occupies 50% or more of the total volume.

4. 4. The phosphor according to claim 1, wherein the scintillator layer contains an activator element in a ratio of 0.01 mol % to 20 mol %.

5. The phosphor according to any one of claims 1 to 4, characterized in that the scintillator layer has one or a combination of two or more of a garnet structure, a bixbyite structure, a perovskite structure, a cuspidine structure, an orthosilicate structure, a pyrosilicate structure, and a pyrochlore structure.

6. A position-sensitive photodetector that detects only the visible light is disposed downstream of the phosphor according to any one of claims 1 to 5, An α ray detector which does not discriminate the radiation on an event-by-event basis, but discriminates only the α rays from among the radiation.

7. A method for producing the phosphor according to any one of claims 1 to 5, comprising the steps of: A method for producing a phosphor, comprising forming the scintillator layer on one surface of the substrate layer by using a laser CVD method.

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