Photodetector unit and radiation detector

Abstract

To provide a light detection unit capable of suppressing a conductive material for grounding from interfering with a photomultiplier tube, and a radiation detector.SOLUTION: A light detection unit 10 includes a photomultiplier tube 11, a circuit part 12, a housing 13, and an elastic conductive member 14. The housing 13 houses the photomultiplier tube 11 and the circuit part 12. The circuit part 12 has a ground terminal 12a to which reference potential is supplied from outside. The elastic conductive member 14 connects a grounding part 13a inside the housing 13 and the ground terminal 12a. A state in which the photomultiplier tube 11 and the circuit part 12 are housed inside the housing 13 is a state that a length between both ends of the elastic conductive member 14 is at least a natural length and a restoring force of at least zero acts between both ends of the elastic conductive member 14.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a photodetector unit and a radiation detector. [Background technology]

[0002] Conventionally, there is known a detector that shields a photomultiplier tube from electromagnetic noise by providing a grounded conductive member in which the photomultiplier tube is housed (see, for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-271076 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-46146 Summary of the Invention [Problem to be solved by the invention]

[0004] The conductive member of the detector according to the above-mentioned prior art may be grounded by being connected to a ground terminal provided in the circuit section of the photomultiplier tube. The conductive member and the ground terminal are connected by, for example, a cable or a conductor, or by a pair of connectors that are directly coupled and separated without using a cable or a conductor. However, providing a pair of connectors poses a problem in that the circuitry and conductive members of the photomultiplier tube become larger. Furthermore, when a cable, conductor, or the like is used, it may be necessary to complete the connection using the cable, conductor, or the like before the photomultiplier tube is housed in the conductive member. In this case, the length of the cable, conductor, or the like is set longer than the minimum length required when the photomultiplier tube is housed in the conductive member. When the photomultiplier tube is housed in the conductive member, any excess length of the cable, conductor, or the like is housed inside the conductive member. For example, if the excess length of the cable, conductor, or the like interferes with the photomultiplier tube's light receiving section so as to block it within the conductive member, the photomultiplier tube's light collection may be hindered.

[0005] The present invention has been made in consideration of the above circumstances, and aims to provide a photodetection unit and a radiation detector that can prevent a grounding conductive member from interfering with a photomultiplier tube. [Means for solving the problem]

[0006] In order to solve the above problems and achieve the above object, the present invention employs the following aspects. (1) A photodetection unit according to one aspect of the present invention includes a photomultiplier tube, a conductive member that houses the photomultiplier tube, a ground terminal that is provided on the photomultiplier tube and to which a reference potential is supplied from the outside, and an elastic conductive member that connects a ground portion inside the conductive member to the ground terminal.

[0007] (2) In the photodetection unit according to (1) above, when the photomultiplier tube is housed inside the conductive member, the length between both ends of the elastic conductive member may be at least equal to or greater than the natural length, and a restoring force of at least zero may act between both ends of the elastic conductive member.

[0008] (3) In the photodetection unit according to (2) above, when the photomultiplier tube is housed inside the conductive member, the length between both ends of the elastic conductive member may be the natural length and may be the same as the distance between the ground terminal and the ground portion.

[0009] (4) In the light detection unit according to (2) above, the elastic conductive member may include a first member having elasticity and a second member having conductivity.

[0010] (5) A radiation detector according to one aspect of the present invention includes the photodetection unit according to any one of (1) to (4) above, and a scintillator optically connected to the photomultiplier tube. [Effects of the Invention]

[0011] According to the light detection unit of the aspect described in (1) above, by providing an elastic conductive member that connects the grounding portion and the grounding terminal, it is possible to prevent the elastic conductive member from interfering with the light receiving portion of the photomultiplier tube and to prevent the photomultiplier tube from catching light.

[0012] In the case of (2) above, it is possible to prevent excess length of the elastic conductive member from occurring inside the conductive member, and to prevent the elastic conductive member from interfering with the light receiving section of the photomultiplier tube.

[0013] In the case of (3) above, it is possible to prevent excessive restoring force from acting on the elastic conductive member inside the conductive member, and to prevent deterioration of the elastic conductive member.

[0014] In the case of (4) above, by imparting elasticity and conductivity to the elastic conductive member by combining a plurality of members, the versatility of the elastic conductive member is improved and the elastic conductive member can be easily formed.

[0015] According to the radiation detector according to the aspect described above in (5), the elastic conductive member is prevented from interfering with the light receiving portion of the photomultiplier tube, thereby making it possible to prevent a decrease in detection efficiency. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a cross-sectional view showing the configuration of a radiation detector including a light detection unit according to an embodiment of the present invention. [Figure 2] 1 is a cross-sectional view showing the configuration of a radiation detector including a photodetection unit according to an embodiment of the present invention, in which a photomultiplier tube and a conductive member are separated from each other; [Figure 3] FIG. 2 is a perspective view showing an elastic conductive member of the light detection unit according to the embodiment of the present invention. [Figure 4] FIG. 10 is a perspective view showing an elastic conductive member according to a first modified example of the embodiment of the present invention. [Figure 5] FIG. 10 is a perspective view showing an elastic conductive member according to a second modified example of the embodiment of the present invention. [Figure 6] FIG. 10 is a perspective view showing an elastic conductive member according to a third modified example of the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, a light detection unit and a radiation detector according to an embodiment of the present invention will be described with reference to the accompanying drawings. Fig. 1 is a cross-sectional view showing the configuration of a radiation detector 1 including a photodetection unit 10 according to an embodiment. Fig. 2 is a cross-sectional view showing the configuration of a radiation detector 1 including a photodetection unit 10 according to an embodiment, showing a state in which a photomultiplier tube 11 and a housing 13 are separated. As shown in FIGS. 1 and 2, the radiation detector 1 is, for example, a scintillation detector, and includes a scintillator 5 and a photodetection unit 10. The scintillator 5 emits light when excited by radiation. The light detection unit 10 outputs an electrical signal corresponding to the light emitted from the scintillator 5. The light detection unit 10 includes, for example, a photomultiplier tube 11, a circuit section 12, a housing 13, and an elastic conductive member 14.

[0018] The photomultiplier tube 11 generates photoelectrons from incident photons from the scintillator 5, amplifies secondary electrons generated by the photoelectrons, and outputs a current due to the amplified secondary electrons. The photomultiplier tube 11 has, for example, a cylindrical outer shape. The photomultiplier tube 11 has, for example, two ends along the central axis O: a first end which is a light receiving section and a second end which is a signal output section. The photon input section of the photomultiplier tube 11 is optically connected to the scintillator 5, for example, via a light guide and a light input window, which are arranged as necessary. The signal output section of the photomultiplier tube 11 is electrically connected to the circuit section 12, for example, via a substrate, etc. The circuit unit 12 includes, for example, a power supply circuit, a voltage divider circuit, and a signal processing circuit. The circuit unit 12 is disposed, for example, at a second end of the photomultiplier tube 11 along the central axis O. The circuit unit 12 includes, for example, a plurality of pin-shaped terminals connected to external devices at the end opposite the photomultiplier tube 11 side, of both ends along the central axis O. The circuit unit 12 includes, as at least one of the plurality of terminals, a ground terminal 12a to which a reference potential for grounding is supplied.

[0019] The housing 13 accommodates the photomultiplier tube 11 and the circuit section 12. The housing 13 has, for example, a cylindrical outer shape. The housing 13 is formed of a conductive material, for example, a metal such as aluminum. As shown in FIG. 2 , the photomultiplier tube 11 and the circuit section 12 are inserted into or removed from the housing 13, for example, in a direction along the central axis O. The housing 13 includes a grounding portion 13a therein that is connected to an elastic conductive member 14. The grounding portion 13a is provided, for example, at one of both ends along the central axis that is closer to the scintillator 5.

[0020] The elastic conductive member 14 is connected to the ground terminal 12a and the ground portion 13a of the housing 13 inside the housing 13, thereby grounding the housing 13 to a reference potential (for example, ground potential). FIG. 3 is a perspective view showing the elastic conductive member 14 of the light detection unit 10 according to the embodiment. 3, the elastic conductive member 14 is formed of an elastic conductive material such as a metal spring, etc. The elastic conductive member 14 is, for example, a metal spiral coil spring.

[0021] 1 and 2, when the photomultiplier tube 11 and the circuit unit 12 are removed from the housing 13 (separated state), both ends of the elastic conductive member 14 are electrically connected to the ground terminal 12a of the circuit unit 12 and the ground portion 13a of the housing 13. The separated state of the photomultiplier tube 11 and the circuit unit 12 from the housing 13 is a state in which the length between both ends of the elastic conductive member 14 is longer than its natural length, and a restoring force acts between both ends of the elastic conductive member 14. When the photomultiplier tube 11 and the circuit unit 12 are housed inside the housing 13 and the photomultiplier tube 11 and the scintillator 5 are optically connected (connected state), the length between both ends of the elastic conductive member 14 is at least equal to or greater than its natural length, and a restoring force of at least zero acts between both ends of the elastic conductive member 14. For example, when the photomultiplier tube 11 is connected, the length between both ends of the elastic conductive member 14 is its natural length and is the same as the distance between the ground terminal 12a of the circuit section 12 and the ground portion 13a of the housing 13, and the restoring force acting between both ends of the elastic conductive member 14 is zero.

[0022] As described above, the photodetection unit 10 according to this embodiment includes the elastic conductive member 14 that electrically connects the ground terminal 12a of the circuit section 12 and the ground portion 13a of the housing 13, thereby preventing excess length of the elastic conductive member 14 from occurring inside the housing 13. This prevents the elastic conductive member 14 from interfering with the light receiving section of the photomultiplier tube 11 and preventing the photomultiplier tube 11 from collecting light. When the photomultiplier tube 11 is connected, the length between both ends of the elastic conductive member 14 inside the housing 13 is its natural length, which prevents excessive restoring force from acting on the elastic conductive member 14 and suppresses deterioration of the elastic conductive member 14.

[0023] According to the radiation detector 1 of this embodiment, the elastic conductive member 14 is prevented from interfering with the light receiving portion of the photomultiplier tube 11, thereby making it possible to prevent a decrease in detection efficiency.

[0024] Modifications of the above-described embodiment will now be described. In the above-described embodiment, the elastic conductive member 14 is formed from an elastic metal, but this is not limited to this and may be formed from a conductive rubber such as a conductive silicone rubber. For example, in the case of the elastic conductive member 14 made of conductive silicone rubber, natural radioactive isotopes ( 40 Compared to natural rubber containing cellulose, which contains cellulose, it is possible to suppress the increase in background radiation. Furthermore, since the elastic conductive member 14 is maintained attached inside the housing 13 except in special cases such as repair of the light detection unit 10, deterioration can be suppressed even if it is made of conductive rubber. Furthermore, in the case of silicone rubber, deterioration can be suppressed more effectively than in the case of other rubbers.

[0025] In the above-described embodiment, the elastic conductive member 14 is configured from a single member, but is not limited to this and may be configured from a plurality of members. FIG. 4 is a perspective view showing an elastic conductive member 14A according to a first modified example of the embodiment. As shown in FIG. 4, the elastic conductive member 14A of the first modified example includes, for example, a first elastic member 21 and a second elastic member 22. The first elastic member 21 is formed of an elastic conductive material such as a metal spring. The first elastic member 21 is, for example, a metal spiral coil spring. The second elastic member 22 is, for example, formed of an elastic material. The second elastic member 22 is, for example, a spiral coil spring disposed outside the first elastic member 21. The first elastic member 21 and the second elastic member 22 may be formed so that the lengths between their ends at the elastic limit are different from each other. For example, the length between their ends at the elastic limit of the first elastic member 21 may be relatively shorter than the length between their ends at the elastic limit of the second elastic member 22.

[0026] FIG. 5 is a perspective view showing an elastic conductive member 14B according to a second modified example of the embodiment. As shown in FIG. 5, the elastic conductive member 14B of the second modified example includes, for example, a third elastic member 23 and a first conductive member 24. The third elastic member 23 is made of an elastic material such as rubber. The third elastic member 23 is, for example, a rod-shaped rubber. The first conductive member 24 is made of a material such as a conductive metal. The first conductive member 24 is, for example, a cylindrical metal braid (a cylindrical member formed by weaving metal wires in a net shape) that is conductive and stretchable and is provided so as to cover the surface of the third elastic member 23.

[0027] FIG. 6 is a perspective view showing an elastic conductive member 14C according to a third modified example of the embodiment. As shown in FIG. 6, the elastic conductive member 14C of the third modified example includes, for example, a fourth elastic member 25 and a second conductive member 26. The fourth elastic member 25 is made of an elastic material such as rubber. The fourth elastic member 25 is, for example, a linear rubber. The second conductive member 26 is made of a material such as a conductive metal. The second conductive member 26 is, for example, a linear metal. The elastic conductive member 14C of the third modified example is, for example, a tubular braid formed by weaving the fourth elastic member 25 and the second conductive member 26 into a net shape.

[0028] According to the second and third modified examples, by imparting elasticity and conductivity through a combination of multiple components, the versatility of the elastic conductive members 14B, 14C is improved and the elastic conductive members 14B, 14C can be easily formed.

[0029] In the above-described embodiment, the housing 13 is provided to house the photomultiplier tube 11 and the circuit unit 12, but this is not limiting and the housing may also house the scintillator 5. The housing that houses the scintillator 5 has an outer shape that covers the outer surface of the scintillator 5, for example. The housing that houses the scintillator 5 may be formed of a conductive material such as metal. The conductive housing that houses the scintillator 5 may be electrically connected to the housing 13 and thereby be grounded together with the housing 13, for example.

[0030] The embodiments of the present invention are presented as examples and are not intended to limit the scope of the invention. These embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are intended to be included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0031] 1...radiation detector, 5...scintillator, 10...photodetection unit, 11...photomultiplier tube, 12...circuit section, 12a...ground terminal, 13...housing (conductive member), 13a...ground portion, 14, 14A, 14B, 14C...elastic conductive members, 21...first elastic member, 22...second elastic member, 23...third elastic member (first member), 24...first conductive member (second member), 25...fourth elastic member (first member), 26...second conductive member (second member).

Claims

1. A photomultiplier tube, a conductive member that houses the photomultiplier tube; a ground terminal provided in the photomultiplier tube and supplied with a reference potential from an external source; an elastic conductive member connecting a grounding portion inside the conductive member and the ground terminal; Equipped with An optical detection unit characterized by:

2. When the photomultiplier tube is housed inside the conductive member, the length between both ends of the elastic conductive member is at least equal to or greater than its natural length, and a restoring force of at least zero acts between both ends of the elastic conductive member.

2. The optical detection unit according to claim 1.

3. When the photomultiplier tube is housed inside the conductive member, the length between both ends of the elastic conductive member is a natural length and is the same as the distance between the ground terminal and the ground portion.

3. The optical detection unit according to claim 2.

4. The elastic conductive member is A first member having elasticity and a second member having electrical conductivity. Equipped with 4. The optical detection unit according to claim 1, wherein the optical detection unit is a light detecting unit.

5. The optical detection unit according to any one of claims 1 to 4, a scintillator optically connected to the photomultiplier tube; Equipped with A radiation detector characterized by:

Images