Radiation detector and radiation detection apparatus

Abstract

This radiation detector is provided with: an optical semiconductor element having a plurality of light-receiving regions; a scintillator unit disposed on the optical semiconductor element; and an adhesive layer disposed between the optical semiconductor element and the scintillator unit. The scintillator unit has at least one scintillator corresponding to the plurality of light receiving regions. Each of the plurality of light-receiving regions has a plurality of light-receiving units connected in parallel with each other. Each of the plurality of light receiving units includes an avalanche photodiode operating in Geiger mode and an arc extinguishing resistor connected in series with the avalanche photodiode. The distance between adjacent light-receiving regions is greater than the distance between the scintillator and the light-receiving region that faces the scintillator.

Description

Technical Field

[0001] The present invention relates to a radiation detector and a radiation detection device. Background Art

[0002] Patent Document 1 describes a radiation detector including a photoelectric conversion element, a filter disposed on the photoelectric conversion element, and a fluorescent element disposed on the filter. In the radiation detector described in Patent Document 1, when radiation is incident on the fluorescent element, light is emitted from the fluorescent element, and only light in a short wavelength band of the light passes through the filter and is incident on the photoelectric conversion element, and the light in the short wavelength band is detected by the photoelectric conversion element.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 10-274675 Summary of the invention

[0006] Problems to be solved by the invention

[0007] In the radiation detector as described above, a photo-semiconductor element having a plurality of light-receiving regions is sometimes used as a photoelectric conversion element, and a scintillator unit having at least one scintillator corresponding to the plurality of light-receiving regions is sometimes used as a fluorescent element. In such a case, light emitted from a certain region in the scintillator due to the incidence of radiation is incident not only on the light-receiving region opposite to the region but also on the light-receiving region adjacent to the light-receiving region, thereby possibly reducing the detection accuracy of radiation.

[0008] An object of the present invention is to provide a radiation detector and a radiation detection apparatus capable of detecting radiation with high accuracy.

[0009] Methods for solving problems

[0010] A radiation detector according to one aspect of the present invention [1] is "a radiation detector comprising: an optical semiconductor element having a plurality of light receiving areas; a scintillator unit arranged on the optical semiconductor element; and an adhesive layer arranged between the optical semiconductor element and the scintillator unit, wherein the scintillator unit has at least one scintillator corresponding to the plurality of light receiving areas, each of the plurality of light receiving areas having a plurality of light receiving parts connected in parallel to each other, each of the plurality of light receiving parts including an avalanche photodiode operating in a Geiger mode and an arc extinguishing resistor connected in series with the avalanche photodiode, and a distance between adjacent light receiving areas in the plurality of light receiving areas being greater than a distance between the plurality of light receiving areas and the relative light receiving areas in the at least one scintillator and the scintillator".

[0011] In the above-mentioned radiation detector, the distance between adjacent light receiving areas is larger than the distance between the opposite light receiving area and the scintillator. Therefore, when a certain area in the scintillator emits light due to the incidence of radiation, the incidence of light to the light receiving area opposite to the area is promoted, and the incidence of light to the light receiving area adjacent to the light receiving area is suppressed. Therefore, according to the above-mentioned radiation detector, radiation can be detected with high accuracy.

[0012] The radiation detector according to one aspect of the present invention may also be [2] "In the radiation detector described in [1] above, the adhesive layer is in contact with each of the optical semiconductor element and the scintillator unit". According to this radiation detector, since there is no interface between a plurality of layers between the optical semiconductor element and the scintillator unit, when a scintillator emits light due to the incidence of radiation, the incidence of light to the light receiving area opposite to the scintillator is further promoted, and the incidence of light to the light receiving area adjacent to the light receiving area is further suppressed.

[0013] A radiation detector according to one aspect of the present invention may also be [3] "In the radiation detector described in [1] above, there is also an optical filter layer arranged between the optical semiconductor element and the scintillator unit, the adhesive layer is arranged between the optical filter layer and the scintillator unit, the optical filter layer is in contact with each of the optical semiconductor element and the adhesive layer, and the adhesive layer is in contact with each of the optical filter layer and the scintillator unit." According to this radiation detector, when light is emitted from a certain area in the scintillator due to the incidence of radiation, with respect to light of a desired wavelength band, the incidence of light to a light receiving area opposite to the area is promoted, and the incidence of light to a light receiving area adjacent to the light receiving area is suppressed.

[0014] A radiation detector according to one aspect of the present invention may also be [4] "In the radiation detector described in any one of [1] to [3] above, the distance between the adjacent light receiving areas is greater than or equal to 0.1 mm". According to this radiation detector, when light is emitted from a certain area in the scintillator due to the incidence of radiation, the incidence of light on the light receiving area adjacent to the light receiving area opposite to the area can be further suppressed.

[0015] A radiation detector according to one aspect of the present invention may be [5] "In the radiation detector described in any one of [1] to [4] above, the width of each of the plurality of light receiving portions is 50 μm or less." According to this radiation detector, for example, even when an offset occurs between the relative light receiving areas and the scintillator, a reduction in energy resolution in the detection of radiation can be suppressed.

[0016] A radiation detector according to one aspect of the present invention may also be [6] "a radiation detector as described in any one of [1] to [5] above, further comprising a wiring substrate on which a plurality of optical semiconductor elements, which are the optical semiconductor elements, are mounted". According to this radiation detector, the size of the optical semiconductor element can be maintained at an appropriate size and the detection range of radiation can be expanded.

[0017] A radiation detector according to one aspect of the present invention may be [7] "In the radiation detector described in [6] above, the plurality of optical semiconductor elements are arranged in one direction, and in each of the plurality of optical semiconductor elements, the plurality of light receiving regions are arranged in the one direction, and the plurality of light receiving regions include a pair of first light receiving regions located at both ends in the one direction and a plurality of second light receiving regions located between the pair of first light receiving regions, and in the one direction, the width of each of the pair of first light receiving regions is smaller than the width of each of the plurality of second light receiving regions". According to this radiation detector, in the case where the scintillator unit has a plurality of scintillators corresponding to the plurality of light receiving regions, even if the arrangement pitch of the plurality of optical semiconductor elements arranged in one direction deviates, the deviation of the scintillator relative to the light receiving region is absorbed by the first light receiving region, so that the deviation of the scintillator relative to the light receiving region can be suppressed from increasing in all the optical semiconductor elements.

[0018] The radiation detector according to one aspect of the present invention may also be [8] "In the radiation detector described in [6] or [7] above, the plurality of optical semiconductor elements are directly mounted on the wiring substrate." According to this radiation detector, the heat generated in each of the plurality of optical semiconductor elements can be efficiently released to the wiring substrate, and the gain (multiplication factor) variation in each of the plurality of optical semiconductor elements or the gain deviation between the plurality of optical semiconductor elements can be reliably suppressed.

[0019] A radiation detector according to one aspect of the present invention may also be [9] "In the radiation detector described in [8] above, the plurality of optical semiconductor elements are fixed to a common pad of the wiring substrate." According to this radiation detector, heat generated by each of the plurality of optical semiconductor elements can be released to the wiring substrate more efficiently, and gain fluctuations in each of the plurality of optical semiconductor elements or gain deviations between the plurality of optical semiconductor elements can be more reliably suppressed.

[0020] A radiation detector according to one aspect of the present invention may also be

[10] "In the radiation detector described in any one of [1] to [9] above, the at least one scintillator is a plurality of scintillators corresponding to the plurality of light receiving areas". According to this radiation detector, when a scintillator emits light due to the incidence of radiation, the incidence of light to the light receiving area opposite to the scintillator is promoted, and the incidence of light to the light receiving area adjacent to the light receiving area is suppressed.

[0021] A radiation detector according to one aspect of the present invention may also be

[11] "In the radiation detector described in

[10] above, the scintillator unit further includes a light reflecting member covering a surface other than a surface on the optical semiconductor element side of each of the plurality of scintillators". According to this radiation detector, when a scintillator emits light due to the incidence of radiation, the incidence of light to a light receiving area opposite to the scintillator is further promoted, and the incidence of light to a light receiving area adjacent to the light receiving area is further suppressed.

[0022] A radiation detection device

[12] according to one aspect of the present invention "is provided with: a radiation detector as described in any one of [1] to

[11] above; and a plurality of signal processing units corresponding to the plurality of light receiving areas, for processing pulse signals outputted from each of the plurality of light receiving areas, wherein each of the plurality of signal processing units has a waveform shaping circuit, a plurality of comparators and a plurality of counters, wherein the waveform shaping circuit shapes the waveform of the pulse signal in such a manner as to shorten the pulse width, wherein each of the plurality of comparators compares the intensity of the pulse signal inputted from the waveform shaping circuit with each of a plurality of different threshold values, and wherein the plurality of counters count the pulse signals having an intensity exceeding each of the plurality of threshold values ​​for each of the plurality of threshold values".

[0023] According to the above-mentioned radiation detection apparatus, it is possible to distinguish the energy of radiation for each of the plurality of light receiving areas.

[0024] The radiation detection device according to one aspect of the present invention may also be

[13] "In the radiation detection device described in

[12] above, each of the plurality of signal processing units further comprises an anode potential correction circuit, and the anode potential correction circuit corrects the potential of the anode side of each of the plurality of light receiving areas for each of the plurality of light receiving areas." According to this radiation detection device, the gain can be adjusted for each of the plurality of light receiving areas.

[0025] The radiation detection device according to one aspect of the present invention may also be

[14] "In the radiation detection device described in

[12] or

[13] above, it is also provided with a cathode potential correction circuit corresponding to the plurality of light receiving areas, and the cathode potential correction circuit corrects the potential of the cathode side of each of the plurality of light receiving areas according to a signal output from a temperature sensor further provided in the radiation detector". According to this radiation detection device, it is possible to suppress the gain of the plurality of light receiving areas from changing due to the temperature of the optical semiconductor element.

[0026] The radiation detection device according to one aspect of the present invention may also be

[15] "In the radiation detection device described in any one of

[12] to

[14] above, it is also provided with a threshold linear correction circuit corresponding to the plurality of light receiving areas, and the threshold linear correction circuit corrects each of the plurality of thresholds in such a manner that each of the plurality of thresholds is equal between the plurality of light receiving areas." According to this radiation detection device, it is possible to suppress the threshold deviation of each input to a plurality of comparators corresponding to each other between the plurality of light receiving areas.

[0027] Effects of the Invention

[0028] According to the present invention, it is possible to provide a radiation detector and a radiation detection apparatus capable of detecting radiation with high accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a top view of a radiation detector according to one embodiment.

[0030] Figure 2 yes Figure 1 A top view of a portion of a radiation detector is shown.

[0031] Figure 3 is along Figure 1 A cross-sectional view of the radiation detector taken along line III-III is shown.

[0032] Figure 4 Yes means Figure 1 The diagram shows the positional relationship between the light receiving area and the scintillator.

[0033] Figure 5 yes Figure 1 A cross-sectional view of a portion of an optical semiconductor element is shown.

[0034] Figure 6 yes Figure 1 Circuit diagram of an optical semiconductor element shown.

[0035] Figure 7 This is a cross-sectional view of a portion of an optical semiconductor element according to a modified example.

[0036] Figure 8It is a graph showing the relationship between the offset of the scintillator relative to the light receiving area and the statistical limit of the energy resolution.

[0037] Fig. 9 yes Figure 3 A cross-sectional view of a portion of a radiation detector is shown.

[0038] Fig.10 It is a graph showing the relationship between radiation energy and light leakage in Examples and Comparative Examples.

[0039] Fig.11 It is a graph showing the energy resolution of the embodiment and the comparative example.

[0040] Fig.12 It is a graph showing the normalized outputs about Examples and Comparative Examples.

[0041] Fig.13 It is a graph showing the relationship between the radiation dose rate and the gain variation in the example and the comparative example.

[0042] Fig.14 This is a block diagram of a radiation detection device according to one embodiment.

[0043] Fig.15 This is a cross-sectional view of a portion of a radiation detector according to a modified example.

[0044] Fig.16 It is a top view of an optical semiconductor element of a radiation detector according to a modified example.

[0045] Fig.17 It is a top view of a radiation detector according to a modified example.

[0046] Fig.18 It is an exploded perspective view of a radiation detector according to a modified example.

[0047] Fig.19 It is an exploded perspective view of a radiation detector according to a modified example. DETAILED DESCRIPTION

[0048] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, in each figure, the same or corresponding parts are marked with the same reference numerals, and repeated descriptions are omitted.

[0049] [Structure of the radiation detector]

[0050] like Figure 1 , Figure 2 and Figure 3As shown, the radiation detector 1 includes a plurality of optical semiconductor elements 2, a plurality of scintillator units 3, an adhesive layer 4, a wiring substrate 5, a plurality of wires 6, a protective resin member 7, and a temperature sensor 8. In the following description, the thickness direction of the wiring substrate 5 is referred to as the Z direction, a direction parallel to the Z direction is referred to as the X direction, and a direction perpendicular to both the Z direction and the X direction is referred to as the Y direction. Figure 1 and Figure 2 In FIG. 1 , the protective resin member 7 is indicated by a two-dot chain line. Figure 2 In FIG. 1 , illustration of the plurality of scintillator units 3 is omitted.

[0051] The wiring substrate 5 has a front side 5a and a back side 5b. When the wiring substrate 5 is observed from the Z direction, it is, for example, in a rectangular shape with the X direction as the long side direction and the Y direction as the short side direction. A mounting pad (pad) 51 is provided on the front side 5a of the wiring substrate 5. The mounting pad 51 has, for example, a predetermined width in the Y direction, and extends in the X direction so as to cross the front side 5a. A plurality of optical semiconductor elements 2 are fixed to a common mounting pad 51 of the wiring substrate 5, for example, by chip bonding, while being arranged in a row along the X direction (one direction). That is, the plurality of optical semiconductor elements 2 are directly mounted on the wiring substrate 5. The temperature sensor 8 is a sensor for measuring the temperature of the plurality of optical semiconductor elements 2, and is mounted on the back side 5b of the wiring substrate 5.

[0052] Each optical semiconductor element 2 has a semiconductor layer 21 and a wiring layer 22. The semiconductor layer 21 has a front surface 21a and a back surface 21b. The wiring layer 22 is formed on the front surface 21a of the semiconductor layer 21. In the present embodiment, the back surface 21b of the semiconductor layer 21 is fixed to the mounting pad 51. When each optical semiconductor element 2 is observed from the Z direction, it is, for example, in a rectangular shape with the X direction as the long side direction and the Y direction as the short side direction. In each optical semiconductor element 2, the semiconductor layer 21 and the wiring layer 22 constitute a plurality of light receiving areas 23. That is, each optical semiconductor element 2 has a plurality of light receiving areas 23. In each optical semiconductor element 2, the plurality of light receiving areas 23 are arranged in a row in the X direction.

[0053] In the X direction, the width of each of the pair of light receiving regions (first light receiving region) 23A is smaller than the width of each of the plurality of light receiving regions (second light receiving region) 23B. A pair of light receiving regions 23A is a pair of light receiving regions located at both ends in the X direction among the plurality of light receiving regions 23 possessed by each optical semiconductor element 2. The plurality of light receiving regions 23B are a plurality of light receiving regions located between the pair of light receiving regions 23A among the plurality of light receiving regions 23 possessed by each optical semiconductor element 2. When each light receiving region 23A is observed from the Z direction, it is, for example, in a rectangular shape with the Y direction as the long side direction and the X direction as the short side direction. When each light receiving region 23B is observed from the Z direction, it is, for example, in a square shape. The length of one side of each light receiving region 23B is, for example, about 1 mm. The distance between adjacent light receiving regions 23 is, for example, about 0.2 mm.

[0054] In each optical semiconductor element 2, a plurality of anode electrode pads 22A and cathode electrode pads 22B are provided on the surface of the wiring layer 22 on the opposite side to the semiconductor layer 21. Each anode electrode pad 22A is located on one side in the Y direction relative to each light receiving region 23. The cathode electrode pad 22B is located on one side in the X direction relative to the plurality of anode electrode pads 22A. One anode electrode pad 22A corresponds to one light receiving region 23 and is electrically connected to the anode side of one light receiving region 23 (details will be described later). The cathode electrode pad 22B corresponds to a plurality of light receiving regions 23 and is electrically connected to the cathode side of a plurality of light receiving regions 23 (details will be described later). Each electrode pad 22A, 22B is separated from each light receiving region 23 by, for example, 1 mm or more in the Y direction.

[0055] A plurality of individual electrode pads 52A and a plurality of common electrode pads 52B are provided on the front surface 5a of the wiring substrate 5. Each individual electrode pad 52A is located on one side in the Y direction relative to each anode electrode pad 22A. Each common electrode pad 52B is located on one side in the Y direction relative to each cathode electrode pad 22B. A plurality of common electrode pads 52B are formed integrally (continuously) with the mounting pad 51. A wire 6 is provided on the corresponding anode electrode pad 22A and the individual electrode pad 52A. Similarly, a wire 6 is provided on the corresponding cathode electrode pad 22B and the common electrode pad 52B.

[0056] The plurality of electrode pads 22A, 22B, 52A, 52B and the plurality of wires 6 are covered with a protective resin member 7. In the radiation detector 1, as described above, each electrode pad 22A, 22B is separated from each light receiving region 23 by, for example, 1 mm or more in the Y direction. Therefore, it is possible to prevent the protective resin member 7 from reaching each light receiving region 23 when manufacturing the radiation detector 1.

[0057] A connector 53 is provided on the back surface 5b of the wiring board 5. The connector 53 is an input / output port of electrical signals in the wiring board 5. In the radiation detector 1, electrical signals are input / output to and from each optical semiconductor element 2 and to and from the temperature sensor 8 via the connector 53.

[0058] The plurality of scintillator units 3 are arranged in a row in the X direction. The plurality of scintillator units 3 correspond to the plurality of optical semiconductor elements 2. Specifically, each scintillator unit 3 is arranged on each optical semiconductor element 2 via an adhesive layer 4. The adhesive layer 4 is arranged between the plurality of optical semiconductor elements 2 and the plurality of scintillator units 3. The adhesive layer 4 is in contact with each of the plurality of optical semiconductor elements 2 and the plurality of scintillator units 3. The material of the adhesive layer 4 is, for example, a silicone adhesive, an epoxy adhesive, or the like. The thickness of the adhesive layer 4 is, for example, less than 100 μm (typically about 20 to 30 μm).

[0059] Each scintillator unit 3 has a plurality of scintillators 31 and a light reflecting member 32. In each scintillator unit 3, the plurality of scintillators 31 are arranged in a row in the X direction. The plurality of scintillators 31 corresponds to the plurality of light receiving regions 23. Specifically, each scintillator 31 is arranged on each light receiving region 23 via an adhesive layer 4. Each scintillator 31 is, for example, in the shape of a rectangular parallelepiped with the Z direction as the long side direction. The cross-sectional shape of each scintillator 31 perpendicular to the Z direction is substantially the same as the shape of each light receiving region 23B when viewed from the Z direction (see FIG. 2 ). Figure 4 ), for example, in a square shape. The material of each scintillator 31 is, for example, LYSO:Ce, YAP:Ce, LuAG:Pr, etc. The width of each scintillator 31 in the X direction and the Y direction is, for example, about 1 mm. The height of each scintillator 31 in the Z direction is, for example, about several mm.

[0060] In each scintillator unit 3, the light reflecting member 32 covers the surface 31a of each scintillator 31 except the surface 31b on the optical semiconductor element 2 side. When radiation (e.g., X-rays, gamma rays, etc.) is incident on a scintillator 31 and the scintillator 31 emits light, the light travels toward the surface 31b or is reflected by the light reflecting member 32, thereby emitting from the surface 31b. The material of the light reflecting member 32 is, for example, titanium oxide. The thickness of the light reflecting member 32 (equivalent to the distance between adjacent scintillators 31) is, for example, about 0.2 mm.

[0061] [Structure of optical semiconductor element]

[0062] As described above, each optical semiconductor element 2 has a plurality of light receiving regions 23. Figure 4As shown, the light receiving region 23 has a plurality of light receiving parts 24. The plurality of light receiving parts 24 are arranged two-dimensionally along a plane perpendicular to the Z direction. In the present embodiment, the plurality of light receiving parts 24 are arranged in a matrix with the X direction as the row direction and the Y direction as the column direction. Each light receiving part 24 is a SPAD (Single Photon Avalanche Diode), and the optical semiconductor element 2 is a SiPM (Silicon Photomultiplier) in which one channel is constituted by one light receiving region 23.

[0063] like Figure 5 As shown, the semiconductor layer 21 includes an N-type semiconductor region 211, a P-type semiconductor region 212 and a P-type semiconductor region 213 for each light receiving portion 24. + The N-type semiconductor region 211 extends over the plurality of light receiving portions 24. The P-type semiconductor region 212 is formed in the N-type semiconductor region 211 along the front surface 21a of the semiconductor layer 21, and forms a pn junction with the N-type semiconductor region 211. + The N-type semiconductor region 211, the P-type semiconductor region 212 and the P-type semiconductor region 213 are formed in the P-type semiconductor region 212 along the front surface 21a of the semiconductor layer 21. + The semiconductor region 213 constitutes an APD (avalanche photodiode) 25. The material of the semiconductor layer 21 is, for example, silicon. In the semiconductor layer 21, P-type impurities are, for example, Group 3 elements such as B, and N-type impurities are, for example, Group 5 elements such as N, P, and As.

[0064] The semiconductor layer 21 has a groove 21c. The groove 21c extends in a manner that separates each P-type semiconductor region 212 from each other. The groove 21c opens at the front surface 21a of the semiconductor layer 21. The depth of the groove 21c from the front surface 21a is greater than the depth of the P-type semiconductor region 212 from the front surface 21a. In each light receiving portion 24, a portion of the N-type semiconductor region 211 is arranged between the P-type semiconductor region 212 and the groove 21c. An insulating region 214 is formed along the inner surface of the groove 21c. The material of the insulating region 214 is, for example, SiO2. A metal member 215 is arranged in the groove 21c. The material of the metal member 215 is, for example, W. The width of the groove 21c is, for example, about 0.5 μm. The depth of the groove 21c is, for example, about several μm.

[0065] The wiring layer 22 has a plurality of arc-extinguishing resistors 26, a plurality of through electrodes 27, a readout wiring 28, and an insulating layer 29 relative to one light receiving region 23. The insulating layer 29 is composed of a plurality of insulating films and extends over a plurality of light receiving regions 23. The material of each insulating film is, for example, SiO2 or SiN. The plurality of arc-extinguishing resistors 26, the plurality of through electrodes 27, and the readout wiring 28 are formed in the insulating layer 29.

[0066] One arc-extinguishing resistor 26 and one APD 25 together constitute one light-receiving unit 24. In each light-receiving unit 24, the arc-extinguishing resistor 26 is arranged along the P direction when viewed from the Z direction. + The arc-extinguishing resistor 26 has one end 26a connected to the P through the through electrode 27. + The arc-extinguishing resistor 26 is electrically connected to the type semiconductor region 213. The other end (not shown) of the arc-extinguishing resistor 26 is electrically connected to the readout wiring 28. The material of the arc-extinguishing resistor 26 is, for example, SiCr. The material of the through electrode 27 is, for example, Al.

[0067] The readout wiring 28 has a plurality of openings 28a. In each light receiving section 24, the opening 28a includes each P + The type semiconductor region 213 and the arc extinguishing resistor 26. In each light receiving region 23, the readout wiring 28 extends over a plurality of light receiving portions 24. The readout wiring 28 is connected to the corresponding anode electrode pad 22A (see Figure 2 ) is electrically connected. The material of the readout wiring 28 is, for example, Al. In addition, the N-type semiconductor region 211 extending over the plurality of light receiving portions 24 in each light receiving region 23 is connected to the cathode electrode pad 22B (see FIG. 1 ) via a through electrode (not shown) or the like. Figure 2 )Electrical connection.

[0068] Figure 6 2 is a circuit diagram of the optical semiconductor element 2. Figure 6 As shown, each light receiving region 23 has a plurality of light receiving parts 24 connected in parallel to each other. Each light receiving part 24 includes an APD 25 and an arc extinguishing resistor 26 connected in series with the APD 25. In each light receiving region 23, the anode of each APD 25 is electrically connected to the anode electrode pad 22A via each arc extinguishing resistor 26, and the cathode of each APD 25 is electrically connected to the cathode electrode pad 22B. Figure 6 The “DAC” shown in .

[0069] In the optical semiconductor element 2, each APD 25 operates in Geiger mode. In Geiger mode, a reverse voltage (reverse bias voltage) greater than the breakdown voltage of the APD 25 is applied to each APD 25. As an example, when each anode electrode pad 22A is grounded via a resistor R, a positive voltage greater than the breakdown voltage of the APD 25 is applied to the cathode electrode pad 22B.

[0070] When light enters any and at least one APD 25 while each APD 25 is operating in the Geiger mode, charges are generated by photoelectric conversion in the APD 25, and the generated charges are amplified by avalanche multiplication. The charges amplified in the APD 25 are output to the anode electrode pad 22A via the corresponding arc extinguishing resistor 26, and are output from the anode electrode pad 22A as a pulse signal to an external signal processing unit.

[0071] [Dimensions related to the light receiving area and scintillator]

[0072] like Figure 5 As shown, the distance D1 between adjacent light receiving regions 23 among the plurality of light receiving regions 23 is greater than the distance D2 between the relative light receiving regions 23 and the scintillator 31 among the plurality of light receiving regions 23 and the plurality of scintillators 31. In the present embodiment, the distance D1 between adjacent light receiving regions 23 is greater than 0.1 mm, and the distance D2 between the relative light receiving regions 23 and the scintillator 31 is less than 0.1 mm. In the present embodiment, the width D3 of each light receiving portion 24 is less than 50 μm.

[0073] The distance D1 between adjacent light receiving regions 23 refers to, with focus on adjacent light receiving regions 23, the shortest distance between “the inner edge of a separation region (in the present embodiment, a region formed by the groove 21c and the insulating region 214) extending along the outer edge of one light receiving region 23 when viewed from the Z direction” and “the inner edge of a separation region (in the present embodiment, a region formed by the groove 21c and the insulating region 214) extending along the outer edge of the other light receiving region 23 when viewed from the Z direction”. The distance D2 between the relative light receiving region 23 and the scintillator 31 refers to the shortest distance between “the surface on the scintillator 31 side of the semiconductor layer 21 where a plurality of APDs 25 are formed (in the present embodiment, the front surface 21a)” and “the surface on the semiconductor layer 21 side of the scintillator 31 (in the present embodiment, the surface 31b)”. When viewed from the Z direction, the width D3 of the light receiving portion 24 refers to the width of the portion defined by the inner edge of the separation region (a region formed by the groove 21c and the insulating region 214 in this embodiment), and refers to the width of the portion in each of the X and Y directions.

[0074] Here, the isolation region is a region that suppresses the depletion layer 20 from expanding outward in the APDs 25 arranged along the outer edges of the light receiving regions 23. In the present embodiment, the isolation region is a region composed of the trench 21c and the insulating region 214. As an example, the isolation region may be a region composed of an N-type semiconductor region 212 surrounding the P-type semiconductor region 212 in each APD 25 when viewed from the Z direction. + The area composed of type semiconductor regions.

[0075] In addition, if Figure 7 As shown, the distance D1 when no separation region is provided refers to, with regard to adjacent light receiving regions 23, the shortest distance between “the outer edge of the depletion layer 20 when the depletion layer 20 is maximally extended in the APD25 arranged along the outer edge of one light receiving region 23” and “the outer edge of the depletion layer 20 when the depletion layer 20 is maximally extended in the APD25 arranged along the outer edge of the other light receiving region 23”. The width D3 of the light receiving portion 24 when no separation region is provided refers to the width of the depletion layer 20 when the depletion layer 20 is maximally extended in the APD25, that is, the width of the depletion layer 20 in each of the X direction and the Y direction. Alternatively, the width D3 of the light receiving portion 24 when no separation region is provided refers to the distance between adjacent P in one light receiving region 23. + The center-to-center distance of the semiconductor region 213 (the center-to-center distance when viewed from the Z direction).

[0076] Figure 8 Graph showing the relationship between the offset of the scintillator 31 relative to the light receiving area 23 and the statistical limit of energy resolution. In this simulation, samples 1 to 5 were prepared. In samples 1 to 5, the shape of the light receiving area 23 when viewed from the Z direction was set to a 1 mm × 1 mm square, and the cross-sectional shape of the scintillator 31 perpendicular to the Z direction was set to a 1 mm × 1 mm square. Based on this, in sample 1, the shape of the light receiving portion 24 when viewed from the Z direction was set to a 15 μm × 15 μm square. In sample 2, the shape of the light receiving portion 24 when viewed from the Z direction was set to a 25 μm × 25 μm square. In sample 3, the shape of the light receiving portion 24 when viewed from the Z direction was set to a 50 μm × 50 μm square. In sample 4, the shape of the light receiving portion 24 when viewed from the Z direction was set to a 75 μm × 75 μm square. In sample 5, the shape of the light receiving section 24 when viewed from the Z direction was set to a square shape of 100 μm×100 μm. In addition, in samples 1 to 5, the distances between adjacent light receiving sections 24 were the same.

[0077] like Figure 4 As shown, while making the offset d of the scintillator 31 relative to the light receiving area 23 equal in the X direction and the Y direction, the offset is changed, and for each of the samples 1 to 5, the statistical limit of the energy resolution is calculated for each offset. At this time, the amount of incident light is set to 960 photons, and the detection efficiency (Photon Detection Efficiency) is set to 50%. Usually, in order to achieve energy discrimination of radiation, an energy resolution of less than 40% is required. In addition, usually, the offset of the scintillator 31 relative to the light receiving area 23 is in the range of tens to 100 μm. As Figure 8As shown, within the range of the offset amount of several tens to 100 μm, the energy resolution statistical limit is 40% or less for samples 1 to 3. From the simulation results, it is known that the width D3 of each light receiving portion 24 is preferably 50 μm or less.

[0078] [Functions and effects of radiation detectors]

[0079] In the radiation detector 1, the distance D1 between adjacent light receiving regions 23 is greater than the distance D2 between the opposing light receiving region 23 and the scintillator 31. Fig. 9 As shown, through the radiation ( Fig. 9 The solid line shown in FIG. 1 is incident on a scintillator 31 and emits light ( Fig. 9 When the scintillator 31 is aligned with the dotted line shown in FIG. 1 , the incidence of light to the light receiving area 23 opposite to the scintillator 31 is promoted, and the incidence of light to the light receiving area 23 adjacent to the light receiving area 23 is suppressed. Therefore, according to the radiation detector 1, radiation can be detected with high accuracy.

[0080] In the radiation detector 1, the adhesive layer 4 disposed between the plurality of optical semiconductor elements 2 and the plurality of scintillator units 3 is in contact with each of the plurality of optical semiconductor elements 2 and the plurality of scintillator units 3. As a result, there is no interface between the plurality of layers between the corresponding optical semiconductor elements 2 and the scintillator units 3, so when a certain scintillator 31 emits light due to the incidence of radiation, the incidence of light to the light receiving area 23 opposite to the scintillator 31 is further promoted, and the incidence of light to the light receiving area 23 adjacent to the light receiving area 23 is further suppressed.

[0081] In the radiation detector 1 , the distance D1 between adjacent light receiving regions 23 is 0.1 mm or more. This can further suppress the incidence of light on light receiving regions 23 adjacent to the light receiving region 23 facing the scintillator 31 when a scintillator 31 emits light due to incident radiation.

[0082] In the radiation detector 1 , the width D3 of each light receiving portion 24 is 50 μm or less. This can suppress a decrease in energy resolution in radiation detection even when, for example, a misalignment occurs between the light receiving region 23 and the scintillator 31 that face each other.

[0083] In the radiation detector 1, a plurality of optical semiconductor elements 2 are mounted on a wiring board 5. This allows the detection range of radiation to be expanded while maintaining the size of each optical semiconductor element 2 at an appropriate size.

[0084] In the radiation detector 1, a plurality of optical semiconductor elements 2 are arranged in the X direction, and in each optical semiconductor element 2, a plurality of light receiving regions 23 are arranged in the X direction. In addition, the width of each of a pair of light receiving regions 23A located at both ends in the X direction among the plurality of light receiving regions 23 is smaller than the width of each of a plurality of light receiving regions 23B located between the pair of light receiving regions 23A among the plurality of light receiving regions 23. Thus, even when the arrangement pitch of the plurality of optical semiconductor elements 2 arranged in the X direction is deviated, since the displacement of the scintillator 31 relative to the light receiving region 23 is absorbed by the light receiving region 23A, it is possible to suppress the displacement of the scintillator 31 relative to the light receiving region 23 from becoming larger in all the optical semiconductor elements 2.

[0085] In the radiation detector 1, a plurality of optical semiconductor elements 2 are directly mounted on a wiring substrate 5. Thus, the heat generated in each optical semiconductor element 2 can be efficiently released to the wiring substrate 5, and the gain (multiplication factor) variation in each optical semiconductor element 2 or the gain deviation between the plurality of optical semiconductor elements 2 can be reliably suppressed.

[0086] In the radiation detector 1, a plurality of optical semiconductor elements 2 are fixed to a common mounting pad 51 of a wiring substrate 5. Thus, the heat generated in each optical semiconductor element 2 can be released to the wiring substrate 5 more efficiently, and gain fluctuations in each optical semiconductor element 2 or gain deviations between a plurality of optical semiconductor elements 2 can be more reliably suppressed.

[0087] The effect is further explained using an embodiment and a comparative example. As a radiation detector of the embodiment, similarly to the above-mentioned radiation detector 1, a radiation detector is prepared in which only an adhesive layer 4 is arranged between a plurality of optical semiconductor elements 2 and a plurality of scintillator units 3, and a distance D1 between adjacent light receiving areas 23 is larger than a distance D2 between the opposite light receiving areas 23 and the scintillator 31. As a radiation detector of a comparative example, a radiation detector is prepared as follows: by accommodating a plurality of optical semiconductor elements 2 in a package, an adhesive layer 4 and a protective glass member are arranged between the plurality of optical semiconductor elements 2 and a plurality of scintillator units 3, and a distance D2 between the opposite light receiving areas 23 and the scintillator 31 is larger than a distance D1 between adjacent light receiving areas 23.

[0088] Fig.10 Graphs showing the relationship between radiation energy and light leakage in the embodiment and the comparative example. In each of the radiation detectors of the embodiment and the comparative example, gamma rays were made incident on a predetermined scintillator 31, and the signal amount (pe: photoelectron) in the light receiving area 23 adjacent to the light receiving area 23 facing the scintillator 31 was measured as light leakage. The results are as follows. Fig.10As shown, in the radiation detector of the embodiment, there is almost no light leakage for 120 keV gamma rays. For gamma rays above 300 keV, in the radiation detector of the embodiment, light leakage is suppressed to about 40% compared with the radiation detector of the comparative example.

[0089] Fig.11 Graphs showing energy resolution of the embodiment and the comparative example. In each of the radiation detector of the embodiment and the radiation detector of the comparative example, gamma rays are made incident on a predetermined scintillator 31, and the count value in the light receiving area 23 facing the scintillator 31 is measured. As a result, Fig.11 As shown, the energy resolution of the radiation detector of the comparative example for γ-rays of 59.5 keV is 41.5%, whereas the energy resolution of the radiation detector of the embodiment for γ-rays of 59.5 keV is 31.8%. Thus, it is confirmed that the energy resolution of the radiation detector of the embodiment is improved compared with the radiation detector of the comparative example.

[0090] Fig.12 Graphs showing standardized outputs of the embodiment and the comparative example. In each of the radiation detectors of the embodiment and the comparative example, an object having a predetermined length is moved in a scanning direction while being irradiated with X-rays, and the output in a predetermined light receiving area 23 is measured. As a result, Fig.12 As shown, in the radiation detector of the comparative example, the output immediately after the object passes is temporarily increased compared to the output before the object passes, and then the output gradually decreases and becomes equal to the output before the object passes. This means that during the passage of the object, the temperature of the optical semiconductor element 2 decreases, and the gain of the light receiving area 23 increases. After the object passes, the temperature of the optical semiconductor element 2 gradually increases, and the gain of the light receiving area 23 gradually decreases. In contrast, in the radiation detector of the embodiment, the output is the same before and after the object passes. This means that by efficiently releasing the heat generated in the optical semiconductor element 2, the temperature of the optical semiconductor element 2 is maintained substantially constant, and the change in gain is suppressed.

[0091] Fig.13 Graphs showing the relationship between the radiation dose rate and gain variation of the embodiment and the comparative example. In each of the radiation detectors of the embodiment and the comparative example, the output in the predetermined light receiving area 23 was measured while X-rays were irradiated. The results are as follows. Fig.13 As shown, it was confirmed that the radiation detector of the embodiment had a temperature stability improved by about 6 times compared with the radiation detector of the comparative example.

[0092] [Radiation detection equipment]

[0093] Fig.14 FIG. 1 is a block diagram of a radiation detection device 10 including the above-mentioned radiation detector 1. Fig.14 As shown in FIG. 1 , the radiation detection device 10 includes a radiation detector 1, a plurality of signal processing units 11, a threshold linear correction circuit 15, and a cathode potential correction circuit 13. Fig.10 Only one signal processing unit 11 is shown in the figure.

[0094] The plurality of signal processing units 11 correspond to the plurality of light receiving regions 23 for each optical semiconductor element 2. That is, one signal processing unit 11 is provided for one light receiving region 23. Each signal processing unit 11 processes a pulse signal output from the corresponding light receiving region 23. As an example, the plurality of signal processing units 11 are physically constituted by one integrated circuit.

[0095] Each signal processing unit 11 includes an anode potential correction circuit 12, a waveform shaping circuit 14, and n (n is an integer greater than or equal to 2) comparators 161 to 16 n , n counters 171~17 n The waveform shaping circuit 14 shapes the waveform of the pulse signal output from the light receiving area 23. Specifically, the waveform shaping circuit 14 shapes the waveform of the pulse signal so that the pulse width becomes shorter. n The intensity of the pulse signal input from the waveform shaping circuit 14 is compared with each of the threshold values ​​Th1 to Th1 input from the threshold linear correction circuit 15. n Each threshold value Th1~Th n is the threshold value relative to the intensity of the pulse signal, ranging from Th1 to Th n Each counter 171 to 17 n For multiple thresholds Th1~Th n Each of the counts of each has a value exceeding each threshold value Th1 to Th n The intensity of the pulse signal.

[0096] Since the radiation detection device 10 includes the plurality of signal processing units 11 configured as described above, it is possible to distinguish the energy of radiation for each of the plurality of light receiving regions 23. As a result, it is possible to generate a color X-ray image of the object or measure the density of a plurality of substances.

[0097] The anode potential correction circuit 12 corrects the potential of the anode side of each of the plurality of light receiving regions 23. Specifically, Figure 6 As shown, for each light receiving area 23, the anode potential correction circuit 12 adjusts the potential between the anode electrode pad 22A and the resistor R (at Figure 6The anode potential correction circuit 12 (the potential indicated by "DAC" in FIG. 1 ) is corrected so that the gains of the light receiving regions 23 are equal. Thus, for example, even when a voltage of 46V is applied to the cathode electrode pad 22B, a voltage is applied individually to each light receiving region 23. Since the signal processing unit 11 includes the anode potential correction circuit 12 having such a configuration, the gain can be adjusted for each of the plurality of light receiving regions 23.

[0098] like Fig.14 As shown, the cathode potential correction circuit 13 corresponds to the plurality of light receiving regions 23. That is, one cathode potential correction circuit 13 is provided for each of the plurality of light receiving regions 23. In the present embodiment, one cathode potential correction circuit 13 is provided for each of the plurality of optical semiconductor elements 2. The cathode potential correction circuit 13 uniformly corrects the potential of the cathode side of each of the plurality of light receiving regions 23 based on the signal output from the temperature sensor 8. Thus, it is possible to suppress the gain of the plurality of light receiving regions 23 from changing due to the temperature of the optical semiconductor element 2.

[0099] The threshold linear correction circuit 15 corresponds to the plurality of light receiving regions 23. That is, one threshold linear correction circuit 15 is provided for each of the plurality of light receiving regions 23. In the present embodiment, one threshold linear correction circuit 15 is provided for each of the plurality of optical semiconductor elements 2. The threshold linear correction circuit 15 provides a threshold linear correction circuit 15 to each of the comparators 161 to 16 n Input threshold values ​​Th1~Th n The threshold linear correction circuit 15 corrects each threshold Th1 to Th n , so that each threshold Th1~Th n The threshold linear correction circuit 15 is based on the threshold linear correction circuit 15 for each of the plurality of signal processing units 11 and for each of the plurality of comparators 161 to 162. n Each of the conversion codes or conversion parameters stored in each of the plurality of signal processing units 11 is used to store a plurality of threshold values ​​Th corresponding to each other. m (m is an arbitrary integer from 1 to n) so that each threshold value Th1 to Th n This can suppress the occurrence of a plurality of light receiving regions 23 (in other words, a plurality of signal processing units 11) sending signals to the corresponding plurality of comparators 16. m Enter the threshold deviation.

[0100] [Modifications]

[0101] The present invention is not limited to the above-mentioned embodiments. Fig.15As shown, an optical filter layer 9 may be arranged between the optical semiconductor element 2 and the scintillator unit 3. As an example, the optical filter layer 9 is composed of a dielectric multilayer film formed on the surface of the optical semiconductor element 2 on the side of the scintillator unit 3. An adhesive layer 4 is arranged between the optical filter layer 9 and the scintillator unit 3. The optical filter layer 9 is in contact with each of the optical semiconductor element 2 and the adhesive layer 4. The adhesive layer 4 is in contact with each of the optical filter layer 9 and the scintillator unit 3. In this case, the distance D1 between the adjacent light receiving regions 23 is also greater than the distance D2 between the opposing light receiving regions 23 and the scintillator 31. The sum of the thickness of the optical filter layer 9 and the thickness of the adhesive layer 4 is, for example, less than 100 μm. In addition, the optical filter layer 9 may be bonded to the surface of the optical semiconductor element 2 on the side of the scintillator unit 3.

[0102] according to Fig.15 In the structure shown in the figure, when a scintillator 31 emits light due to the incidence of radiation, the incidence of light of a desired wavelength band to the light receiving area 23 opposite to the scintillator 31 is promoted, and the incidence of light to the light receiving area 23 adjacent to the light receiving area 23 is suppressed. As an example, the optical filter layer 9 may be configured to filter the light of a short wavelength band ( Fig.15 The dashed line shown) transmits and cuts off the long-wavelength light ( Fig.15 Generally speaking, the decay time constant of light in a short wavelength band (e.g., blue light, ultraviolet light, etc.) is shorter than that of light in a long wavelength band. Therefore, by configuring the radiation detector 1 so that only short wavelength light is detected in the optical semiconductor element 2, the radiation dose rate can be increased.

[0103] In addition, if Fig.16 As shown in FIG. 2 , a plurality of light receiving regions 23 may be arranged two-dimensionally in the optical semiconductor element 2. Fig.16 In the illustrated structure, the plurality of light receiving regions 23 are arranged in a matrix with the X direction as the row direction and the Y direction as the column direction. The plurality of anode electrode pads 22A and cathode electrode pads 22B are located on one side of the plurality of light receiving regions 23 in the Y direction.

[0104] In addition, if Fig.17 As shown in FIG. 1 , a plurality of optical semiconductor elements 2 may be mounted on the wiring substrate 5 in a state of being arranged in two rows. Fig.17 In the structure shown, on one side ( Fig.17 In a row of a plurality of optical semiconductor elements 2 (lower side in the middle), a plurality of anode electrode pads 22A and cathode electrode pads 22B are located on one side in the Y direction relative to a plurality of light receiving regions 23. Fig.17In a row of a plurality of optical semiconductor elements 2 (on the upper side in the middle), a plurality of anode electrode pads 22A and cathode electrode pads 22B are located on the other side in the Y direction relative to a plurality of light receiving regions 23. Fig.17 In FIG. 1 , the protective resin member 7 is indicated by a two-dot chain line. Fig.17 In FIG. 1 , illustration of the plurality of scintillator units 3 is omitted.

[0105] In addition, the optical semiconductor element 2 may be a back-illuminated type. That is, in the semiconductor layer 21, a plurality of P-type semiconductor regions 212 and P + The N-type semiconductor region 213 may be arranged along the surface of the semiconductor layer 21 opposite to the scintillator unit 3. In this case, a groove 21c may be formed in the semiconductor layer 21, which is open on the surface of the semiconductor layer 21 opposite to the scintillator unit 3 and separates the P-type semiconductor regions 212 from each other. In addition, in the optical semiconductor element 2 that functions as a SiPM, each light receiving portion 24 may have another structure such as a structure in which the N-type and P-type are opposite. As an example, the N-type semiconductor region 211, the P-type semiconductor region 212, and the P-type semiconductor region 213 may be arranged along the surface of the semiconductor layer 21 opposite to the scintillator unit 3. In this case, the semiconductor layer 21 may have a groove 21c that is open on the surface of the semiconductor layer 21 opposite to the scintillator unit 3 and separates the P-type semiconductor regions 212 from each other. + The semiconductor regions 213 may be P-type semiconductor regions, N-type semiconductor regions, - The material of the semiconductor layer 21 is not limited to silicon, but may be a compound semiconductor. In addition, in the optical semiconductor element 2, the wiring layer 22 may not be formed on the front surface 21a of the semiconductor layer 21. In addition, in the above-mentioned embodiment, in the wiring substrate 5, the mounting pad 51 is electrically connected to the plurality of common electrode pads 52B, but the mounting pad 51 may not be electrically connected to the plurality of common electrode pads 52B. In addition, the radiation detector 1 only needs to include at least one optical semiconductor element 2.

[0106] In the configuration where a plurality of optical semiconductor elements 2 are mounted on the wiring substrate 5, the optical semiconductor elements 2 may be arranged in four directions with respect to one optical semiconductor element 2. Fig.18 and Fig.19 A structure in which such optical semiconductor elements 2 can be arranged will be described.

[0107] exist Fig.18In the structure shown, with a focus on one optical semiconductor element 2, an ASIC (application specific integrated circuit) 100, the optical semiconductor element 2, an adhesive layer 4, and a scintillator unit 3 are sequentially stacked on the front surface 5a of the wiring substrate 5. The optical semiconductor element 2 has a plurality of light receiving areas 23 arranged in a matrix with the X direction as the row direction and the Y direction as the column direction. The optical semiconductor element 2 is, for example, a back-illuminated type, and a plurality of anode electrode pads (not shown) and cathode electrode pads (not shown) are provided on the surface of the wiring substrate 5 side in the optical semiconductor element 2. The ASIC 100 is electrically connected to the wiring substrate 5 via a plurality of bump electrodes 54 and fixed to the wiring substrate 5. The optical semiconductor element 2 is electrically connected to the ASIC 100 via a plurality of direct bonding electrodes 101 provided on the surface of the optical semiconductor element 2 side in the ASIC 100 and fixed to the ASIC 100. The scintillator unit 3 is fixed to the optical semiconductor element 2 via the adhesive layer 4.

[0108] exist Fig.19 In the structure shown, when focusing on one optical semiconductor element 2, the optical semiconductor element 2, the adhesive layer 4 and the scintillator unit 3 are stacked in this order on the front surface 5a of the wiring substrate 5. The ASIC 100 is mounted on the back surface 5b of the wiring substrate 5. The optical semiconductor element 2 has a plurality of light receiving areas 23 arranged in a matrix with the X direction as the row direction and the Y direction as the column direction. The optical semiconductor element 2 is, for example, a surface incident type, and a plurality of anode electrode pads (not shown) and cathode electrode pads (not shown) led out by through electrodes are provided on the surface of the wiring substrate 5 side of the optical semiconductor element 2. The optical semiconductor element 2 is electrically connected to the wiring substrate 5 via a plurality of bump electrodes 54 and fixed to the wiring substrate 5. The scintillator unit 3 is fixed to the optical semiconductor element 2 via the adhesive layer 4.

[0109] In addition, in the above-mentioned embodiment, one scintillator 31 corresponds to one light receiving region 23, but one scintillator 31 may correspond to a plurality of light receiving regions 23. In this case, the plurality of light receiving regions 23 may be all the light receiving regions 23 of the optical semiconductor element 2, or may be a part of the light receiving regions 23 of the optical semiconductor element 2. In addition, in the above-mentioned embodiment, the scintillator unit 3 has the light reflecting member 32, but the scintillator unit 3 may not have the light reflecting member 32. That is, the scintillator unit 3 only needs to have at least one scintillator 31 corresponding to the plurality of light receiving regions 23. In this case, the distance D1 between adjacent light receiving regions 23 is also greater than the distance D2 between the opposing light receiving region 23 and the scintillator 31, so when light is emitted in a certain region in the scintillator 31 due to the incidence of radiation, the incidence of light to the light receiving region 23 opposing the region is promoted, and the incidence of light to the light receiving region 23 adjacent to the light receiving region 23 is suppressed.

[0110] For example, when the scintillator 31 is composed of a plurality of columnar crystals extending in the Z direction, or when the scintillator 31 is relatively thin, it is not necessary to make one scintillator 31 correspond to one light receiving region 23, and it is not necessary for the scintillator unit 3 to have a light reflecting member 32. In these cases, the scintillator unit 3 may also have at least one of a protective film and a light reflecting film covering the surface of the scintillator 31 other than the surface on the optical semiconductor element 2 side. In addition, in one light receiving region 23, the depletion layer 20 may be connected between a plurality of APDs 25.

[0111] Description of Reference Numerals

[0112] 1…Radiation detector

[0113] 2…Optical semiconductor devices

[0114] 3…Scintillator unit

[0115] 4…Adhesive layer

[0116] 5…Wiring board

[0117] 8…Temperature sensor

[0118] 9…Optical filter layer

[0119] 10…Radiation detection equipment

[0120] 11…Signal Processing Unit

[0121] 12…Anode potential correction circuit

[0122] 13…Cathode potential correction circuit

[0123] 14…Waveform shaping circuit

[0124] 161~16 n …Comparator

[0125] 171~17 n …counter

[0126] 23…Light receiving area

[0127] 23A…Light receiving area (first light receiving area)

[0128] 23B…Light receiving area (second light receiving area)

[0129] 24…Light receiving part

[0130] 25…APD (Avalanche Photodiode)

[0131] 26…Arc extinguishing resistor

[0132] 31…Scintillator

[0133] 31a…Surface

[0134] 31b…face

[0135] 32…Light reflecting member

[0136] 51 ... mounting pad (pad).

Claims

1. A radiation detector, wherein: have: An optical semiconductor element having a plurality of light receiving areas; a scintillator unit disposed on the optical semiconductor element; and an adhesive layer disposed between the optical semiconductor element and the scintillator unit, The scintillator unit has at least one scintillator corresponding to the plurality of light receiving areas. Each of the plurality of light receiving regions has a plurality of light receiving parts connected in parallel to each other. Each of the plurality of light receiving parts comprises: Avalanche photodiode operating in Geiger mode; and an arc-quenching resistor connected in series with the avalanche photodiode, A distance between adjacent light receiving regions among the plurality of light receiving regions is greater than a distance between an opposing light receiving region among the plurality of light receiving regions and the at least one scintillator and the scintillator.

2. The radiation detector according to claim 1, wherein: The adhesive layer is in contact with each of the optical semiconductor element and the scintillator unit.

3. The radiation detector according to claim 1, wherein: It also comprises: an optical filter layer disposed between the optical semiconductor element and the scintillator unit, The adhesive layer is disposed between the optical filter layer and the scintillator unit. The optical filter layer is in contact with each of the optical semiconductor element and the adhesive layer. The adhesive layer is in contact with each of the optical filter layer and the scintillator unit.

4. The radiation detector according to any one of claims 1 to 3, wherein: The distance between the adjacent light receiving areas is greater than 0.1 mm.

5. The radiation detector according to any one of claims 1 to 4, wherein: The width of each of the plurality of light receiving parts is 50 μm or less.

6. The radiation detector according to any one of claims 1 to 5, wherein: The radiation detector further includes a wiring board on which a plurality of optical semiconductor elements, each of which is the optical semiconductor element, are mounted.

7. The radiation detector according to claim 6, wherein: The plurality of optical semiconductor elements are arranged in one direction, In each of the plurality of optical semiconductor elements, the plurality of light receiving regions are arranged in the one direction, The plurality of light receiving areas include: a pair of first light receiving areas located at both ends in the one direction; and a plurality of second light receiving regions located between the pair of first light receiving regions, In the one direction, a width of each of the pair of first light receiving regions is smaller than a width of each of the plurality of second light receiving regions.

8. The radiation detector according to claim 6 or 7, wherein: The plurality of optical semiconductor elements are directly mounted on the wiring substrate.

9. The radiation detector according to claim 8, wherein: The plurality of optical semiconductor elements are fixed to a common pad included in the wiring substrate.

10. The radiation detector according to any one of claims 1 to 9, wherein: The at least one scintillator is a plurality of scintillators corresponding to the plurality of light receiving areas.

11. The radiation detector according to claim 10, wherein: The scintillator unit further includes a light reflecting member covering a surface other than a surface on the optical semiconductor element side of the surfaces of each of the plurality of scintillators.

12. A radiation detection device, wherein: have: The radiation detector according to any one of claims 1 to 11; and a plurality of signal processing units corresponding to the plurality of light receiving regions and processing the pulse signals outputted from the plurality of light receiving regions respectively; Each of the plurality of signal processing units includes a waveform shaping circuit, a plurality of comparators, and a plurality of counters. The waveform shaping circuit shapes the waveform of the pulse signal in such a way that the pulse width becomes shorter. Each of the plurality of comparators compares the intensity of the pulse signal input from the waveform shaping circuit with each of a plurality of threshold values ​​different from each other. Each of the plurality of counters counts the pulse signals having an intensity exceeding each of the plurality of thresholds for each of the plurality of thresholds.

13. The radiation detection device according to claim 12, wherein: Each of the plurality of signal processing units further includes an anode potential correction circuit. The anode potential correction circuit corrects the potential on the anode side of each of the plurality of light receiving regions for each of the plurality of light receiving regions.

14. The radiation detection device according to claim 12 or 13, wherein: It also includes: a cathode potential correction circuit corresponding to the plurality of light receiving areas, The cathode potential correction circuit collectively corrects the potential on the cathode side of each of the plurality of light receiving regions based on a signal output from a temperature sensor further included in the radiation detector.

15. The radiation detection device according to any one of claims 12 to 14, wherein: It also includes: a threshold linear correction circuit corresponding to the plurality of light receiving areas, The threshold linear correction circuit corrects each of the plurality of thresholds so that each of the plurality of thresholds is equal among the plurality of light receiving areas.

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