WO2004112083A1

WO2004112083A1 - Multi anode-type photoelectron intensifier tube and radiation detector

Info

Publication number: WO2004112083A1
Application number: PCT/JP2003/007420
Authority: WO
Inventors: Teruhiko Yamaguchi; Suenori Kimura; Minoru Suzuki; Yoshitaka Nakamura
Original assignee: Hamamatsu Photonics K.K.
Priority date: 2003-06-11
Filing date: 2003-06-11
Publication date: 2004-12-23
Also published as: EP1638130B1; EP1638130A4; JPWO2004112083A1; EP1638130A1; AU2003242281A1

Abstract

A measurement tube (11) integrally comprises along its tube axis a tube head section (17), a funnel-shaped connection section (15), and a tube main body section (13). The size of a cross section substantially perpendicular to the tube axis of the tube head section is larger than the size of a cross section substantially perpendicular to the tube axis of the tube main body section. The curvature radius of each bent corner of the tube head section is smaller than the curvature radius of each bent corner of the tube main body section. The length of the tube head section along its tube axis is shorter than the length of the tube main body section along its tube axis. A photoelectric surface (20) is formed in a region located inside the tube head section on a face on the side to which the tube head section of an incidence face plate (9) is connected. A multi anode-type photoelectron intensifier tube (1) enables effective incidence of light in the photoelectric surface and has high strength.

Description

Description Multi-anode type photomultiplier tube and radiation detector

The present invention relates to a multi-anode type photomultiplier and a radiation detector using the multi-anode type photomultiplier. Background art

Japanese Patent Application Laid-Open No. Hei 5-933781 (hereinafter referred to as Patent Document 1) describes a radiation detector 200 shown in FIG. The radiation detector 200 includes a scintillator matrix 201 and a multi-anode type photomultiplier tube 203.

In the scintillator matrix 201, a plurality of scintillators 202 are arranged in a two-dimensional matrix, and generate and output scintillation light according to incident radiation. The multi-anode type photomultiplier tube 203 detects the scintillation light output from the scintillator matrix. By performing a centroid calculation or the like on output signals from a plurality of anode electrodes in the multi-anode type photomultiplier tube 203, a scintillator that has output scintillation light can be determined.

Japanese Patent Application Laid-Open No. H11-250853 (hereinafter referred to as Patent Literature 2) discloses a multi-anode type photomultiplier tube used for a radiation detector, which is provided with a hollow rectangular prism-shaped side tube made of glass. We have proposed a multi-anode type photomultiplier tube.

Such a multi-anode type photomultiplier tube includes a glass incident surface plate and a tube axis connected to a surface on one side of the incident surface plate and substantially perpendicular to the incident surface plate. And a hollow quadrangular prism-shaped side tube made of glass. A photoelectric surface for emitting photoelectrons corresponding to the light incident on the incident surface plate is formed in an area located inside the side tube on a surface of the incident surface plate to which the side tube is connected. A plurality of electron multipliers and a plurality of anode electrodes are provided inside the side tube corresponding to a plurality of regions of the photocathode.

On the other hand, Japanese Patent Application Laid-Open No. 3-173560 (hereinafter referred to as Patent Document 3) describes a split-type photomultiplier tube. The side tube of this photomultiplier tube has a hollow rectangular column-shaped cylinder head with a large cross-sectional diameter and a hollow rectangular column-shaped cylindrical main body with a small cross-sectional diameter. The tube head is connected to one side of the entrance face plate. A single anode electrode is arranged in the cylinder main body. Disclosure of the invention

Here, similarly to the side tube of Patent Document 3, the glass square side tube described in Patent Document 2 is combined with a square column head having a large cross section and a square column body having a small cross section. It is possible to change to a structure having Since the cross-sectional diameter of the tube head is large, it is possible to increase the size of the photocathode formed in a region of the entrance face plate located inside the side tube.

However, if the length of the tube head in the tube axis direction is longer than the length of the tube body in the tube axis direction as in the side tube of Patent Document 3, the strength of the entire side tube becomes insufficient.

On the other hand, if the hollow quadrangular prismatic side tube is made of glass, the four corners of the side tube will be curved. For this reason, the area of the region located inside the corner of the side tube in the incident face plate becomes small.

Here, in the radiation detector, it is important that the scintillation light from all the scintillators of the scintillator matrix be incident on the photocathode almost uniformly to be converted into photons. However, the corner of the side tube is greatly curved In this case, among the plurality of scintillators constituting the scintillator matrix, the incidence efficiency from the scintillator at the position corresponding to the corner of the side tube is lower than the incidence efficiency from other scintillators. For this reason, the scintillation light from the scintillator cannot be made to enter the photocathode almost uniformly.

The present invention has been made in order to solve the above-mentioned problems, and a multi-anode type photomultiplier tube which can effectively convert light into a photocathode and convert it into photoelectrons and has high intensity, and An object of the present invention is to provide a radiation detector that can detect scintillation light from all scintillators substantially uniformly by providing an anode-type photomultiplier tube. ―

In order to solve the above-mentioned problems, a multi-anode type photomultiplier according to the present invention comprises a glass incident surface plate, and a tube axis connected to one surface of the incident surface plate and substantially perpendicular to the incident surface plate. A hollow side tube made of glass extending along the light-emitting surface, and a photoelectric surface for emitting photoelectrons corresponding to light incident on the incident surface plate is provided on the one side surface of the incident surface plate. A multi-anode type formed in a region located inside, and provided with a plurality of electron multipliers and a plurality of anode electrodes corresponding to a plurality of regions of the photoelectric surface inside the side tube. In a photomultiplier tube, the side tube integrally includes a tube head, a funnel-shaped connecting portion, and a tube main body along the tube axis, and the tube main body includes four first tubes. It has a hollow substantially quadrangular prism shape having a curved corner, extends along the pipe axis by a first length, and is substantially perpendicular to the pipe axis of the cylinder main body. The straight cross section has a first size, the four first curved corners are each curved at a first radius of curvature, and the cylinder head has four second curved corners The tubular head has a substantially quadrangular prism shape, extends along the pipe axis by a second length, and a cross section of the cylinder head that is substantially perpendicular to the pipe axis has a second size. The second curved corners are each curved at a second radius of curvature; The length is shorter than the first length, the second size is larger than the first size, the second radius of curvature is smaller than the first radius of curvature, and the funnel-shaped connection is The cylinder head and the cylinder body are coaxially connected, the cylinder head is connected to the one side surface of the incident face plate, and the photoelectric surface is connected to the one side of the incident face plate. The plurality of electron multipliers and the plurality of anode electrodes are formed in a region located on the inner side of the cylinder head, and the plurality of electron multipliers and the plurality of anode electrodes are provided inside the cylinder main body.

According to the multi-anode type photomultiplier of the present invention, the cross section of the cylinder head is larger than the cross section of the cylinder main body. Therefore, it is possible to increase the area of the incident face plate connected to the cylinder head located inside the cylinder head. Therefore, the size of the photocathode can be increased, and much light can be effectively incident on the photocathode and converted into photoelectrons.

In addition, the radius of curvature of the curved corner of the cylinder head is smaller than the radius of curvature of the curved corner of the cylinder body. Therefore, it is possible to increase the area of a region of the incident face plate near the curved corner of the cylinder head and located inside the curved corner. For this reason, the area of the photocathode near the curved corner can be increased, and most of the light incident near the curved corner of the cylinder head can be effectively incident on the photocathode and converted into photoelectrons.

In addition, since the length of the tube main body in the tube axis direction is longer than the tube head, the strength of the entire vacuum vessel can be increased.

Set the cross-sectional size of the cylinder head and the radius of curvature of the curved corner of the cylinder head to the desired values, and also increase the length of the cylinder main body, the length of the cylinder head, and the cross-section of the cylinder main body. By adjusting the radius of curvature of the curved corner of the cylinder body in accordance with the cross-sectional size of the cylinder head and the radius of curvature of the curved corner of the cylinder head, the area of the photocathode can be reduced. With the desired size, the light near the curved corner of the tube head can be effectively incident on the photocathode, and the strength of the entire side tube can be maintained sufficiently high. Here, the cylinder head has an outer peripheral surface and an inner peripheral surface, and the outer peripheral surface connects two adjacent second curved corners in a substantially straight line, and the inner peripheral surface has two inner curved surfaces. Two adjacent second curved corners are connected in a curved line, and the inner peripheral surface of the two second curved corners is substantially at a center position between each two adjacent second curved corners. It is preferable to gradually approach the outer peripheral surface as one goes. The area of the region near the curved corner of the cylinder head and inside the curved corner of the incident face plate can be further increased. For this reason, the area of the photocathode near the curved corner can be further increased, and more light incident near the curved corner of the cylinder head can be incident on the photocathode and converted into photoelectrons.

Here, the multi-anode type photomultiplier of the present invention further comprises: a focusing electrode plate for focusing the photoelectrons emitted from the photoelectric surface; and an electron focusing device defined between the photoelectric surface and the focusing electrode plate. A partition plate for dividing the space into a plurality of segment spaces corresponding to a plurality of regions of the photocathode, wherein each electron multiplier receives photoelectrons converged by the focusing electrode plate in the corresponding segment space. The partitioning plate extends from the cylinder head to the cylinder main body through the funnel-shaped connecting portion in the side tube, the focusing electrode plate, the plurality of electron multipliers, and the plurality of anodes. It is preferable that an electrode is disposed in the cylinder main body, and a magnetic shield is provided on an outer periphery of the cylinder main body. By arranging a focusing electrode plate, a plurality of electron multipliers, and a plurality of anode electrodes in the cylinder main body and providing a magnetic shield around the outer periphery of the cylinder main body, the operation of converging and multiplying photoelectrons is performed. It can be performed accurately without being affected by an external magnetic field.

According to another aspect, in the radiation detector of the present invention, a plurality of scintillators are arranged in a two-dimensional matrix, each scintillator has an output surface, and each scintillator enters the scintillator. A scintillation light is generated according to the radiation, and the scintillation light is output from the output surface. A radiation detector comprising: a scintillator matrix; and a multi-anode photomultiplier tube for detecting scintillation light output from each scintillator of the scintillator matrix. A light incident surface plate made of glass, and a hollow glass side tube connected to a surface on one side of the light incident surface plate and extending along a tube axis substantially perpendicular to the light incident surface plate; The surface opposite to the one side faces the output surface of all the scintillators of the scintillator matrix, and the photoelectric surface for emitting photoelectrons according to the scintillation light incident on the incident surface plate is provided on the incident surface plate. A plurality of electron multipliers and a plurality of anode electrodes are formed in a region of the one side surface located inside the side tube, and correspond to a plurality of regions of the photocathode. The side pipe is provided integrally with a pipe head, a funnel-shaped connecting part, and a pipe main body along the pipe axis, and the pipe main body is provided with four first pipes. A substantially rectangular pillar shape having a curved corner portion, extending along the tube axis by a first length, and a cross section of the tube main body substantially perpendicular to the tube axis having a first size. The four first curved corners are each curved at a first radius of curvature, and the cylinder head has a hollow substantially quadrangular prism shape having four second curved corners. A section extending substantially along the pipe axis by a second length, a cross section of the cylinder head substantially perpendicular to the pipe axis has a second size, and each of the four second curved corners is Curving at a second radius of curvature, wherein the second length is less than the first length, the second magnitude is greater than the first magnitude, and the second radius is the first radius. Smaller than the radius of curvature of The cylinder head and the cylinder main body are coaxially connected, the cylinder head is connected to the one side surface of the entrance face plate, and the photoelectric surface is connected to the one side surface of the entrance face plate. And wherein the plurality of electron multipliers and the plurality of anode electrodes are formed in a region located inside the tube head, and the plurality of electron multipliers and the plurality of anode electrodes are provided inside the tube main body.

According to the radiation detector of the present invention, the tube of the multi-anode type photomultiplier tube The cross-sectional size of the head is larger than the cross-sectional size of the cylinder body, and the curved corner of the cylinder head is curved with a smaller radius of curvature than the curved corner of the cylinder body. Therefore, most of the output surface of the scintillator located at the outer peripheral portion or the corner of the scintillator matrix can be opposed to the region inside the cylinder head of the incident surface plate. Therefore, the photocathode can receive the scintillation light from all the scintillators at a substantially uniform ratio, and can detect radiation with a substantially uniform sensitivity. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a perspective view showing a conventional radiation detector.

FIG. 2 is a plan view of the multi-anode type photomultiplier according to the first embodiment of the present invention.

FIG. 3 is a vertical sectional view of the multi-anode type photomultiplier tube in FIG. 2 taken along the line III-III.

FIG. 4 is a perspective view showing a glass container provided in the multi-anode type photomultiplier according to the first embodiment of the present invention.

FIG. 5 is a longitudinal sectional view of the glass container of FIG.

FIG. 6 is a cross-sectional view taken along the line VI-VI of the glass container in FIG. 5. FIG. 7 is a cross-sectional view taken along the line VI-VI of the glass container in FIG.

FIG. 8 is a top view of the glass container in FIG.

FIG. 9 is a schematic plan view schematically showing a state where a plurality of radiation detectors according to the first embodiment are arranged.

FIG. 10 is a vertical sectional view taken along line X--X in FIG.

FIG. 11 is an enlarged view of a main part E in FIG. FIG. 12 is a cross-sectional view of a tube head of a glass container provided in a multi-anode type photomultiplier according to a second embodiment of the present invention.

FIG. 13 is a plan view of a multi-anod type photomultiplier according to a comparative example.

Fig. 14 shows the XIV-X of the multi-anode type photomultiplier shown in Fig. 13.

FIG. 5 is a vertical sectional view taken along the line IV.

FIG. 15 is a schematic plan view schematically showing a state in which a plurality of radiation detectors of a comparative example are arranged.

FIG. 16 is a vertical sectional view taken along the line XVI-XVI of FIG.

FIG. 17 is an enlarged view of the main part H of FIG.

FIG. 18 shows that the diameter of the cylinder head in the first and second embodiments is larger than the diameter of the cylinder part of the comparative example, and the radius of curvature of the curved corner of the cylinder head is the cylinder of the comparative example. Since the area of the effective photoelectric region obtained by each of the multi-anode type photomultiplier tubes of the first and second embodiments is smaller than the radius of curvature of the curved portion, the area of the effective anode region is the multi-anode type photomultiplier tube of the comparative example. FIG. 4 is an explanatory view showing that the area is larger than the area of the effective photoelectric region obtained by the above method.

FIG. 19 shows that the diameter of the cylinder head of the first and second embodiments is larger than the diameter of the cylinder of the comparative example, and the radius of curvature of the curved corner of the cylinder head is the cylinder of the comparative example. Since the radius of curvature is smaller than the radius of curvature of the curved corner, the scintillator effective area ratio of the four scintillators located near the corner of the scintillator matrix in the radiation detectors of the first and second embodiments is smaller than that of the comparative example. FIG. 4 is an explanatory diagram showing that the scintillator effective area ratio of four scintillators located near the corner of the scintillator matrix in the radiation detector is larger than that.

FIG. 20 shows that the diameter of the cylinder head in the first and second embodiments is equal to the diameter of the cylinder part of the comparative example, and the radius of curvature of the curved corner of the cylinder head is the comparative example. Even when the radius of curvature of the cylindrical curved corner portion is smaller than that of the comparative example, the area of the effective photoelectric region obtained by each of the multi-anod type photomultiplier tubes of the first and second embodiments is different from that of the comparative example. FIG. 9 is an explanatory diagram showing that the area is larger than the area of an effective photoelectric region obtained by a C type photomultiplier tube.

FIG. 21 shows that the diameter of the cylinder head in the first and second embodiments is equal to the diameter of the cylinder of the comparative example, and the radius of curvature of the curved corner of the cylinder head is the cylinder of the comparative example. Even when the radius of curvature is smaller than the radius of curvature of the curved corner, the scintillator effective area ratio of the four scintillators located near the corner of the scintillator matrix in the radiation detectors of the first and second embodiments is set to be smaller than that of the comparative example. FIG. 4 is an explanatory diagram showing that the scintillator effective area ratio of four scintillators located near the corner of the scintillator matrix in the radiation detector is larger than that. BEST MODE FOR CARRYING OUT THE INVENTION

A multi-anode type photomultiplier tube and a radiation detector according to an embodiment of the present invention will be described with reference to the drawings.

First, a multi-anode type photomultiplier tube and a radiation detector according to a first embodiment of the present invention will be described with reference to FIG. 2 to FIG. First, the multi-anode type photomultiplier according to the present embodiment will be described.

FIG. 2 is a plan view of the multi-anod type photomultiplier tube 1 of the present embodiment.

FIG. 3 is a vertical cross-sectional view of the multi-anode type photomultiplier tube 1 taken along the line III_III in FIG.

Multi-anode type photomultiplier tube 1 is a 2 x 2 multi-anode type It is.

As shown in FIGS. 2 and 3, the multi-anode type photomultiplier tube 1 includes a glass container 5 made of transparent glass.

As shown in FIG. 3, the glass container 5 includes a hollow side tube 11 made of transparent glass and an entrance face plate 9 made of transparent glass.

The side tube 11 extends along a tube axis substantially perpendicular to the entrance face plate 9. The side tube 11 integrally includes a tube head 17, a funnel-shaped connecting portion 15, and a tube main body 13 along the tube axis. The upper end of the cylinder head 17 of the side tube 11 is joined to the lower surface 9 d of the entrance face plate 9. The area inside the cylinder head 17 of the lower surface 9 d of the entrance face plate 9 is hereinafter referred to as “effective photoelectric area K”.

A transparent glass stem 7 is joined to the lower end of the cylinder body 13 to seal the inside of the glass container 5.

Inside the glass container 5, a photocathode 20, a focusing electrode plate 22, a partition plate 26, an electron multiplying unit 28, and an anode unit 32 are provided. Also, input / output pins 38 are provided through the stem 7.

The photoelectric surface 20 is formed in the effective photoelectric region of the incident surface plate 9.

The focusing electrode plate 22 is a disk-shaped electrode plate. As shown in FIG. 2, four apertures 24 are formed in the focusing electrode plate 22.

The electron multiplier 28 includes four dynode arrays 30. FIG. 3 shows two of the four dynode arrays 30. Each dynode row 30 is composed of 10 dynodes Dy1 to Dy10.

The anode section 32 includes four anode electrodes 34. FIG. 3 shows two of the four anode electrodes 34.

The anode part 32 is further provided with four shield electrodes 36. FIG. 3 shows two of the four shield electrodes 36. The magnetic shield 40 is provided so as to cover the outer periphery of the cylinder main body 13. The magnetic shield 40 is made of a high magnetic permeability material 42 and a resin coating 44. In the present embodiment, since the glass container 5 of the multi-anod type photomultiplier tube 1 has the shape described below, more light can be effectively incident on the photocathode 20 and a high vacuum Has achieved strength.

The shape of the glass container 5 will be described with reference to FIGS. First, the outline of the shape of the glass container 5 will be described with reference to FIG. FIG. 4 is a perspective view of the glass container 5.

The tube main body 13 is a hollow substantially quadrangular prism extending along the tube axis, and has four side surfaces 13a and four curved corners 13b. The cross section of the cylinder body 13 substantially perpendicular to the tube axis is substantially square.

The cylinder head 17 is also a hollow substantially quadrangular prism extending along the tube axis, and has four side faces 17a and four curved corners 17b. The cross section of the cylinder head 17 that is substantially perpendicular to the tube axis is also substantially square.

Funnel shape (funnel shape) The connection part 15 connects the cylinder main body part 13 to the cylinder head 17 coaxially.

The incident surface plate 9 is a substantially square glass plate. The entrance surface plate 9 has an upper surface 9u, a lower surface 9d, four side surfaces 9a, and four curved corners 9b. Both the upper surface 9u and the lower surface 9d are substantially square.

The four side faces 9a of the entrance face plate 9 are connected to the four side faces 17a of the cylinder head 17, and the four curved corners 9b of the entrance face plate 9 are the four curved corners of the cylinder head 17 It is connected to 17b.

Hereinafter, the shape of the glass container 5 will be described in more detail with reference to FIG. 5 to FIG.

FIG. 5 is a longitudinal sectional view of the glass container 5.

The cylinder head 17 has an outer peripheral surface 17o and an inner peripheral surface 17i. Juanne The connector 15 has an outer peripheral surface 15o and an inner peripheral surface 15i. The tube body 13 has an outer peripheral surface 13o and an inner peripheral surface 13i. The outer peripheral surface 17 ο of the cylinder head 17 and the outer peripheral surface 13 ο of the cylinder main body 13 are connected by the outer peripheral surface 15 ο of the funnel-shaped connecting portion 15. The inner peripheral surface 17 i of the cylinder head 17 and the outer peripheral surface 13 i of the cylinder main body 13 are connected by the inner peripheral surface 15 i of the funnel-shaped connecting portion 15.

The length L 1 of the tube body 13 in the tube axis direction is longer than the length L 2 of the tube head 17 in the tube axis direction.

The outer diameter W 2 of the cylinder head 17 is larger than the outer diameter W 1 of the cylinder body 13. The inner diameter W2 'of the cylinder head 17 is also larger than the inner diameter W1' of the cylinder body 13.

The outer diameter of the entrance face plate 9 is equal to the outer diameter W 2 of the cylinder head 17.

FIG. 6 is a cross-sectional view of the glass container 5 taken along the line VI-VI in FIG. 5, that is, a cross-sectional view of the cylinder main body 13.

The outer peripheral surface 13 o of the cylinder body 13 has a length W1 between the two adjacent curved corners 13 b of the four curved corners 13 b (the outer diameter of the cylinder outer 13). It is connected in a substantially straight line at. The outer peripheral surface 13ο is curved at a curved corner portion 13b with a radius of curvature (outside radius of curvature) R1.

The inner peripheral surface 13 i of the cylinder main body 13 extends along the outer peripheral surface 13 ο so that the distance from the outer peripheral surface 13 o (thickness T 1 of the cylinder main body 13) is substantially uniform. Prolonged. That is, the inner peripheral surface 13 i connects each two adjacent curved corners 13 b in a substantially straight line with a length W 1 ′ (= W1-2 XT 1: inner diameter of the cylinder body 13). Out. The inner peripheral surface 13 i is curved at the curved corner portion 13 b with a radius of curvature (inner radius of curvature) R 1 ′. The inner radius of curvature R l and the outer radius of curvature R 1 are substantially equal.

FIG. 7 is a cross-sectional view of the glass container 5 taken along line VII-VII of FIG. 5, that is, a cross-sectional view of the cylinder head 17. The outer peripheral surface 17 o of the cylinder head 17 connects two adjacent curved corners 17 b in a substantially straight line with a length W 2 (outer diameter of the cylinder head 17). The outer peripheral surface 17o is curved at a curved corner 17b with a radius of curvature (outside radius of curvature) R2. The outer radius of curvature R 2 is smaller than the outer radius of curvature R 1 of the cylinder body 13.

The inner peripheral surface 17 i of the cylinder head 17 extends along the outer peripheral surface 17 o so that the distance from the outer peripheral surface 17 o (thickness T 2 of the cylinder head 17) is substantially uniform. Prolonged. That is, the inner peripheral surface 17 i is substantially straight with two adjacent curved corners 17 b each having a length W 2, (= W 2 _ 2 x T 2: inner diameter of the cylinder head 17). Are tied together. The thickness Τ2 of the cylinder head 17 is substantially equal to the thickness Τ1 of the cylinder body 13. The inner peripheral surface 17i is curved by a radius of curvature (inner radius of curvature) R2 'at a curved corner 17b. The inner radius of curvature R 2 ′ is substantially equal to the outer radius of curvature R 2. Therefore, the inner radius of curvature R 2, is also smaller than the inner radius of curvature R 1, of the cylinder body 13.

FIG. 8 is a top view of the glass container 5 in FIG.

The incident face plate 9 has the same shape and size as the outer shape of the cylinder head 17. That is, the radius of curvature of the curved corner 9 b of the entrance face plate 9 is equal to the outer radius of curvature R 2 of the curved corner 17 b of the cylinder head 17. Each side surface 9a of the entrance face plate 9 is formed by straightening the two curved corners 9b located on both sides with a length W2 (outer diameter of the entrance face plate) equal to the outer diameter W2 of the cylinder head 17. Are tied together. The area inside the inner peripheral surface 17 i of the cylinder head 17 on the lower surface 9 d of the entrance face plate 9 is the effective photoelectric region K.

The glass container 5 having the above shape can be manufactured by the following method. First, an internal mold for preparing the side tube 11 is prepared. The shape of the outer peripheral surface of the inner mold matches the shape of the inner peripheral surface of the side tube 11. A transparent glass is drawn to a desired thickness before the inner mold. As a result, side tube 1 1 Made. Note that the side tube 11 can be made of either soft glass or hard glass. Next, the lower surface 9d of the entrance face plate 9 is fusion-fixed to the upper end of the cylinder head 17 of the side tube 11. As a result, the glass container 5 is manufactured.

Next, the internal structure of the multi-anode type photomultiplier according to the present embodiment will be described with reference to FIGS. 2 and 3.

As described above, the photoelectric surface 20 is formed in the effective photoelectric region K of the incident surface plate 9.

The focusing electrode plate 22 opposes the photocathode 20 and focuses the photoelectrons emitted from the photocathode 20 so as to be incident on the electron multiplier 28. The four openings 24 are two-dimensionally arranged in two rows and two columns.

The partition plate 26 divides the electron focusing space defined between the photocathode 20 and the focusing electrode plate 22 into a 2-row, 2-column segment space N corresponding to a 2-row, 2-column opening 24. It is for. The photocathode 20 has a 2-row, 2-column area corresponding to the 2-row, 2-column segment space N. The photoelectrons emitted from one region of the photocathode 20 are converged by the converging electrode plate 22 while flying in the corresponding segment space N, and the corresponding aperture 24 of the converging electrode plate 22 To reach the electron multiplier section 28.

In the electron multiplier section 28, the four dynode rows 30 are arranged so as to face the four openings 24 on a one-to-one basis. Each dynode row 30 is for multiplying the photoelectrons that have entered through the corresponding aperture 24. The dynodes Dy1 to Dy10 are arranged in a line focus type in the tube axis direction.

In the anode section 32, four anode electrodes 34 are arranged in one-to-one correspondence with the four dynode rows 30. Each anode electrode 34 is disposed between the dynode Dy9 of the ninth stage and the dynode Dy10 of the tenth stage of the corresponding dynode row 30 so as to face these. Each of the anode electrodes 34 receives the photoelectrons multiplied by the corresponding dynode row 30 and outputs an output signal indicating the amount of photoelectrons.

The four shield electrodes 36 are for electrically shielding the four anode electrodes 34 from each other.

The input / output pins 38 are connected to the photocathode 20, the focusing electrode plate 22, the electron multiplier section 28, and the anode section 32 by wiring (not shown), and are fixed through the stem 7. ing.

As described above, in the present embodiment, 2 × 2 dynode rows 30 and 2 × 2 anode electrodes 34 are provided corresponding to the 2 × 2 segment space N. Each dynode array 30 receives and multiplies photoelectrons emitted from the corresponding area of the photocathode 20. The corresponding anode electrode 34 receives the photoelectron and outputs an output signal indicating the amount of the photoelectron via the input / output pin 38 to the outside.

The partition plate 26 extends across the cylinder head 17 of the side tube 11, the funnel-shaped connection portion 15, and the cylinder main body 13. On the other hand, the focusing electrode plate 22, the electron multiplier section 28, and the anode section 32 are arranged in the cylinder main body 13.

The magnetic shield 40 is for shielding the focusing electrode plate 22, the electron multiplier 28, and the anode 32 located inside the cylinder body 13 from an external magnetic field. The high magnetic permeability material 42 is made of, for example, permalloy, and directly covers the outer periphery of the tube main body 13. The resin coating 44 covers the outer periphery of the high magnetic permeability material 42. The resin coating 44 is for fixing the high magnetic permeability material 42 to the photomultiplier tube 1.

The multi-anode type photomultiplier tube 1 of the present embodiment having the above structure operates as follows.

Photocathode 20, focusing electrode plate 22, anode 32, and electron multiplier A predetermined voltage is applied to 28 through an input / output pin 38. When light enters a region corresponding to one segment space N of the incident surface plate 9, an amount of photoelectrons corresponding to the amount of the incident light is emitted from the corresponding region of the photocathode 20. When the photoelectrons fly through the segment space N, they are converged by the focusing electrode plate 22, pass through the corresponding aperture 24, and enter the corresponding dynode array 30. Here, the photoelectrons are multiplied by multiple stages, collected at the corresponding anode electrode 34, and output as an output signal via the input / output pin 38. From this output signal, it is possible to know how much light is incident on the region facing the segment space N in the incident face plate 9.

Further, in the present embodiment, the focusing electrode plate 22, the electron multiplier section 28, and the anode section 32 are arranged in the cylinder body section 13, and a magnetic field is provided around the cylinder body section 13. A shield 40 is provided. For this reason, the convergence and multiplication of photoelectrons are performed accurately without being affected by an external magnetic field.

In the multi-anode type photomultiplier tube 1 of the present embodiment, the outer diameter W 2 of the cylinder head 17 and the incidence face plate 9 is larger than the outer diameter W 1 of the cylinder body 13, and the cylinder head 17 The inner diameter W 2 is also larger than the inner diameter W 1 ′ of the cylinder body 13. For this reason, the area of the effective photoelectric region K of the lower surface 9d of the incident surface plate 9 can be increased, and a large amount of light can be incident on the photoelectric surface 20 and converted into photoelectrons.

Moreover, in the present embodiment, the outer radius of curvature R2 of the curved corner portion 17b of the cylinder head 17 is smaller than the outer radius of curvature R1 of the curved corner portion 13b of the cylinder body 13. Also, the inner radius of curvature R 2 ′ of the curved corner 17 b of the cylinder head 17 is smaller than the inner radius of curvature R 1 of the curved corner 13 b of the cylinder body 13. For this reason, the area of the effective photoelectric region K inside the curved corner 17b in the region near the curved corner 17b can be increased. Therefore, around the curved corner 17 b In this case, the area of the photocathode 20 can be increased, and the light that has reached the vicinity of the curved corner 17 b can be effectively incident on the photocathode 20.

The strength of the cylinder head 17 is low because the outer diameter and the inner diameter are large and the radius of curvature of the curved corner portion 17b is small. However, the cylinder main body 13 having a small outer diameter and inner diameter and a large radius of curvature of the curved corner portion 13b supports the cylinder head 17. For this reason, the strength of the entire side tube 11 is sufficiently high. In addition, since the length L1 of the tube body 13 in the tube axis direction is longer than the length L2 of the tube head 17 in the tube axis direction, the overall strength of the side tube 11 is further increased.

As described above, in the present embodiment, the size of the cross section substantially perpendicular to the tube axis of the cylinder head 17 is larger than the size of the cross section substantially perpendicular to the tube axis of the cylinder main body 13. The radius of curvature of the four curved corners 17 b of 7 is smaller than the radius of curvature of the four curved corners 13 b of the cylinder body 13, and the length of the cylinder head 17 along the pipe axis is It is shorter than the length of the main body 13 along the pipe axis. Therefore, the size of the cylinder head 17 and the radius of curvature of the curved corner portion 17 b are set to desired sizes according to the application, and the length of the cylinder body 13, the length of the cylinder head 17, Adjust the size of the cylinder body 13 and the radius of curvature of the curved corner 13 b according to the size of the cylinder head 17 and the radius of curvature of the curved corner 17 b. This makes it possible to maintain the strength of the entire side tube 11 sufficiently high.

Next, a radiation detector 50 according to the first embodiment will be described with reference to FIGS. 9 to 11.

FIG. 9 is a schematic plan view schematically showing a state in which a plurality of (in this case, three) radiation detectors 50 according to the present embodiment are arranged one-dimensionally so as to be adjacent to each other. FIG. 10 is a vertical sectional view of the plurality of radiation detectors 50 of FIG. 9 taken along the line X-X. FIG. 11 is an enlarged view showing a main part E shown in FIG. 10 in an enlarged manner.

As shown in FIG. 10, the radiation detector 50 is a multi-anode type photoelectric converter. It has a photomultiplier tube 1 and a scintillator matrix 52. The multi-anode photomultiplier tube 1 has the structure described with reference to FIGS. 2 and 3. In FIG. 10, illustration of the internal structure of the multi-anode type photomultiplier tube 1 is omitted for clarity.

The scintillator matrix 52 is for generating scintillation light according to the incidence of radiation. As shown in FIG. 9 and FIG. 10, the scintillator matrix 52 is composed of a plurality of (36 in this example) scintillators 54 arranged in a 6-dimensional X6 row in a two-dimensional matrix. It is arranged and configured. Each scintillator 54 has a rectangular parallelepiped shape having a substantially square cross section, and has a substantially square output surface (lower surface) 54d. When radiation is incident on the scintillator 54, the scintillator 54 generates scintillation light corresponding to the amount of the radiation, and outputs the scintillation light as scattered light from the output surface 54d.

The upper surface 9 u of the entrance face plate 9 of the multi-anode type photomultiplier tube 1 is bonded to these output faces 54 d while facing the output faces 54 d of all scintillators 54 of the scintillator matrix 52. I have.

FIG. 9 also schematically shows the positional relationship between the output surface 54 d of the 36 scintillators 54 constituting the scintillator matrix 52 and the effective photoelectric area K of the entrance surface plate 9. As is clear from this figure, among the 36 scintillators 54 of the scintillator matrix 52, the scintillator 54 located on the outer peripheral portion of the scintillator matrix 52, It faces the periphery of the cylinder head 17 through the intermediary. In particular, the scintillators 54 located at the four corners of the scintillator matrix 52 face the four curved corners 17 b of the cylinder head 17 via the four curved corners 9 b of the entrance face plate 9. are doing.

Here, when arranging multiple radiation detectors 50, adjacent cylinder heads Parts 17 must be separated by the minimum necessary space S without direct contact. This is to prevent adjacent cylinder heads 17 from being damaged by colliding with each other.

For this reason, in the present embodiment, the outer diameter W 1 of the tube main body 13 of the multi-anode type photomultiplier tube 1, the outer diameter W 2 of the entrance face plate 9 and the tube head 17, the tube head 17 Has the following relationship with respect to the outer diameter W of the scintillator matrix 52. The thickness of the magnetic shield 40 is M. The magnetic shield thickness M is larger than the space S. The outer diameter W 1 of the cylinder body 13 is equal to the outer diameter W of the scintillator matrix 52. The outer diameter W2 of the entrance face plate 9 and the cylinder head 17 is the thickness of the magnetic shield 40 from the outer diameter Wl of the cylinder body 13, that is, the outer diameter W of the scintillator matrix 52. The difference between M and the minimum required space amount S (M-S) is large. The inner diameter W 2 ′ of the cylinder head 17 is smaller than the outer diameter W 2 by twice the thickness T 2. Here, it is assumed that 2 × T 2 is slightly larger than (M−S). Therefore, the inner diameter W 2 ′ of the cylinder head 17 is slightly smaller than the outer diameter W of the scintillator matrix 52.

When the radiation detectors 50 having the above dimensions are arranged so that the adjacent magnetic shields 40 are substantially in contact with each other, as shown in FIG. 11, the adjacent cylinder heads 17 have the minimum necessary space. It can be separated by an amount S. As a result, the adjacent scintillator matrices 52 are separated from each other by a fixed amount equal to the thickness の of the magnetic shield 40.

The outer diameter W2 of the entrance face plate 9 and the cylinder head 17 is larger than the outer diameter W of the scintillator matrix 52, and the inner diameter W2 'of the cylinder head 17 is larger than the outer diameter W of the scintillator matrix 52. Because of the small size, as shown in Fig. 9, most of the output surface 54d of the scintillator 54 located on the outer periphery of the scintillator matrix 52 Effective photoelectric area K Can face each other.

Furthermore, in the present embodiment, the curvature radii R 2 and R 2 ′ of the curved corner portion 17 b are set to desired small values. Therefore, most of the output surface 54 d of the scintillator 54 located at the four corners of the scintillator matrix 52 can face the effective photoelectric region K inside the curved corner 1 Ίb. it can.

Further, according to the present embodiment, when the area of the photocathode 20 needs to be further increased, for example, when the number of scintillators 54 constituting the scintillator matrix 52 is to be increased, the cylinder head 17 is required. The cross-sectional areas W 2 and W 2 ′ may be further increased, and the radius of curvature R 2 and R 2 ′ of the curved corner 17 b may be set to a desired value. Then, in order to maintain the strength of the entire side tube 11, the length L 1 of the tube body 13, the length L 2 of the tube head 17, the cross-sectional area W 1, W of the tube body 13 The curvature radii R 1, R 1 of the curved corner portion 1 3 b, and the cross-sectional area W 2, W 2 of the cylinder head 17, and the curvature radius R 2, of the curved corner portion 17 b It may be adjusted according to the value of R 2 '. By increasing the area of the photocathode 20, the light in the vicinity of the curved corner 17b can be made to effectively enter the photocathode 20, and the intensity of the entire side tube 11 can be kept sufficiently high.

The radiation detector 50 according to the present embodiment having the above structure operates as follows.

When a radiation (specifically, a gamma ray) is incident on one scintillator 54 in one radiation detector 50, the scintillator 54 generates scintillation light. The scintillation light is incident as scattered light from the output surface 54 d of the scintillator 54 on the incident surface plate 9 of the photomultiplier, and is converted into photoelectrons on the photoelectric surface 20. The photoelectrons are multiplied by the electron multiplier section 28 and extracted from the anode section 32 as four output signals. An arithmetic unit (computer), not shown, outputs these four output signals. Signal, and calculate the center of gravity to calculate these ratios. The calculation result indicates which scintillator 54 the radiation has entered. Since the plurality of radiation detectors 50 are arranged at regular intervals so as to be adjacent to each other, the distribution of the incident position of radiation can be detected over a wide range.

In the present embodiment, since the outer diameter W 2 and inner diameter W 2 of the cylinder head 17 are large, the output surface 5 of the scintillator 54 located on the outer periphery of the scintillator matrix 52 Most of 4d can be opposed to the effective photoelectric area K inside the cylinder head 17, that is, the photoelectric surface 20.

In addition, since the radius of curvature (outer radius of curvature R 2 and inner radius of curvature R 2 ′) of the curved corner 17 b of the cylinder head 17 is small, it is located at each corner of the scintillator matrix 52. Most of the output surface 54 d of the scintillator 54 can face the photocathode 20 inside the curved corner 17 b of the cylinder head 17.

Therefore, not only does all of the output light from the scintillator 54 located at the center of the scintillator matrix 52 impinge on the photocathode 20 but also from the scintillator 54 located at the outer periphery. Almost all of the output light can be made incident on the photocathode 20. For this reason, the photocathode 20 can receive the scintillation light from all the scintillators 54 at a substantially uniform rate, and can detect radiation with substantially uniform sensitivity.

In particular, in the present embodiment, the magnetic shield 40 is provided on the outer periphery of the cylinder main body 13 having the smaller outer diameter of the side tube 11. For this reason, the outer diameter W2 of the cylinder head 17 can be increased to substantially the same as the outer diameter obtained by combining the outer diameter W1 of the cylinder main body 13 and the thickness M of the magnetic shield 40. Therefore, the size of the photocathode 20 can be increased. In addition, the shape of the entire side tube 11 including the magnetic shield 40 may be a shape having almost no step. Can be handled easily.

Hereinafter, a multi-anod type photomultiplier tube 1 and a radiation detector 50 according to the second embodiment will be described.

First, the multi-anode type photomultiplier tube 1 according to the present embodiment will be described with reference to FIGS. 2 to 6 and FIG.

The multi-anode photomultiplier tube 1 according to the present embodiment is the same as the multi-anod photomultiplier tube 1 of the first embodiment, except for the cross-sectional shape of the cylinder head 17.

That is, the multi-anode type photomultiplier tube 1 of the present embodiment has the structure shown in FIGS. 2 and 3. Further, the glass container 5 employed in the multi-anode photomultiplier tube 1 of the present embodiment has an outer shape shown in FIG. 4, a vertical cross-sectional shape shown in FIG. 5, and a top shape shown in FIG. are doing. Further, the cross-sectional shape of the cylinder main body 13 (that is, the VI-VI cross-sectional shape in FIG. 5) is the shape shown in FIG. However, the cross-sectional shape of the cylinder head 17 (that is, the VII-VII cross-sectional shape in FIG. 5) is not the shape shown in FIG. 7, but the shape shown in FIG.

Hereinafter, the cross-sectional shape of the cylinder head 17 in the present embodiment will be described with reference to FIG.

In the present embodiment, the outer shape of the cylinder head 17 is the same as that of the first embodiment (FIG. 7). That is, the outer peripheral surface 17o connects each two adjacent curved corners 17b in a substantially straight line with a length W2 (outer diameter of the cylinder head 17). The curved corner 17b is curved with a radius of curvature (outer radius of curvature) R2. The outer radius of curvature R 2 is smaller than the outer radius of curvature R 1 of the curved corner portion 13 b of the cylinder body 13. The outer diameter W2 is larger than the outer diameter W1 of the cylinder body 13. On the other hand, the inner peripheral surface 17i of the cylinder head 17 has a pincushion shape as if it were cut out toward the curved corner 17b. That is, the cylinder head 17 The inner peripheral surface 17i connects two adjacent curved corners 17b in a curved shape. Here, 內 peripheral surface 17 i ′ is most distant from outer peripheral surface 17 o at the approximate center position between each two adjacent curved corners 17 b, and the corresponding two curved corners 17 As it moves toward b, it gradually approaches the outer peripheral surface 17 o. For this reason, the thickness of the cylinder head 17 (the distance between the outer peripheral surface 17 o and the inner peripheral surface 17 i) T 2 is approximately the center position between two adjacent curved corners 11 b. It takes the maximum value T 2 ma X and gradually decreases as it approaches the curved corner 17 b. For this reason, the inner radius of curvature R 2, at the curved corner 17 b of the inner peripheral surface 17 i, is smaller than the outer radius of curvature R 2, and is therefore smaller than the inner radius of curvature R 1 ′ of the cylinder body 13. Note that the maximum value of the wall thickness T2max is substantially equal to the wall thickness T1 of the cylinder body 1.3. Further, the maximum value T 2 max of the thickness of the present embodiment is substantially equal to the thickness T 2 of the first embodiment. The inner diameter W 2 ′ in the present embodiment is defined as W 2, = W 2 −2 XT 2 max. The inner diameter W2, is larger than the inner diameter W1 'of the cylinder body 13.

The side tube 11 having the above shape can be manufactured by the following method. Prepare an external mold. The shape of the inner peripheral surface of the outer mold matches the shape of the outer peripheral surface of the side tube 11. When glass is blown into the external mold to a desired thickness, side tube 11 of the present embodiment is formed. Note that the side tube 11 of the present embodiment can also be made of soft glass or hard glass.

According to the present embodiment, the inner peripheral surface 17i of the cylinder head 17 has a shape that is hollowed toward the curved corner 17b. For this reason, the area near the curved corner portion 17b in the effective photoelectric area K can be further increased as compared with the first embodiment. Therefore, the light that has reached the vicinity of the curved corner 17b can be more effectively made incident on the photocathode 20 and converted into photoelectrons. Next, the radiation detector 50 according to the present embodiment will be described. The radiation detector 50 according to the present embodiment is the same as the first embodiment described with reference to FIGS. 9 to 11 except that the multi-anode type photomultiplier tube 1 according to the present embodiment is employed. This is the same as the radiation detector 50 of the embodiment. According to the radiation detector 50 according to the present embodiment, since the cylinder head 17 has the cross-sectional shape shown in FIG. 12, it is located at each corner of the scintillator matrix 52. Most of the output surface 54 d of the scintillator 54 can face the photoelectric surface 20 inside the curved corner 17 b of the cylinder head 17. Therefore, the scintillation light from all the scintillators 54 can be photoelectrically converted at a uniform rate, and radiation can be detected with a uniform sensitivity.

Hereinafter, the effects obtained by the multi-anod type photomultiplier tube 1 and the radiation detector 50 of the first and second embodiments are compared with the multi-anode type photomultiplier tube and the radiation detector of the comparative example. And will be described in detail.

First, a multi-anode type photomultiplier tube 101 of a comparative example will be described with reference to FIGS. 13 and 14.

FIG. 13 is a plan view of a multi-anode type photomultiplier tube 101 of a comparative example.

FIG. 14 is a vertical sectional view taken along line XIV-XIV in FIG. As shown in FIGS. 13 and 14, the multi-anode type photomultiplier tube 101 of the comparative example has the same configuration as the side tube 111 and the incident face plate 109 used. This is the same as the multi-anode type photomultiplier tube 1 of the first embodiment. The side tube 111 is formed of only a single cylindrical portion 112, and this cylindrical portion 112 is joined to the lower surface 109d of the entrance face plate 109. The tubular portion 112 has a hollow rectangular column shape like the tubular main portion 13 of the first and second embodiments.

As shown in Fig. 13, the cross section of the cylindrical portion 1 1 2 that is substantially perpendicular to the pipe axis is substantially square. It is. The cylindrical portion 112 has four side surfaces 112a and four curved corners 112b. The cylindrical portion 112 has a substantially uniform thickness. The outer diameter of the cylindrical portion 112 is Wc, the wall thickness is Tc, the inner diameter is Wc, (= Wc-2XTc), the outer radius of curvature of the curved corner portion 112b is Rc, and the inner radius of curvature is Is R c '. The outer radius of curvature Rc and the inner radius of curvature Rc 'are substantially equal. The outer diameter Wc is smaller than the outer diameter R2 of the cylinder head 13 of the first and second embodiments. Also, the inner diameter Wc 'is smaller than the inner diameter R2 of the cylinder head 17 of the first and second embodiments. The outer radius of curvature Rc and the inner radius of curvature Rc 'are larger than the outer and inner radius of curvature R2 and R2' of the first and second embodiments.

The entrance face plate 109 has the same shape and size as the outer shape of the cylindrical portion 112. That is, the incident surface plate 109 is a substantially square plate. The entrance surface plate 109 has four curved corners 109 b curved with a radius of curvature Rc and two adjacent curved corners 109 b with a length equal to the outer diameter Wc. Side surface 109 a. The photoelectric surface 120 is formed in the effective photoelectric region K located inside the cylindrical portion 112 of the lower surface 109 d of the incident surface plate 109.

Further, a magnetic shield 40 covers the outer periphery of the lower portion of the cylindrical portion 112. The magnetic shield 40 is composed of a highly magnetically permeable material 42 and a resin film 44 as in the first and second embodiments.

Next, a radiation detector 150 of a comparative example employing the multi-anode type photomultiplier tube 101 of the comparative example will be described with reference to FIGS. 15 to 17. FIG.

FIG. 15 is a schematic plan view schematically showing a state where a plurality of radiation detectors 150 of the comparative example are arranged one-dimensionally so as to be adjacent to each other. FIG. 16 is a vertical sectional view taken along the line XVI-XVI of FIG. FIG. 17 is an enlarged view showing the main part H shown in FIG. 16 in an enlarged manner. In the radiation detector 150 of the comparative example, the scintillator matrix 52 is adhered to the incident face plate 109 of the multi-anode type photomultiplier tube 101 of the comparative example. The multi-anode type photomultiplier tube 101 has the structure described with reference to FIG. 13 and FIG. In FIG. 16, the internal structure of the multi-anode photomultiplier tube 101 is not shown for clarity.

Similarly to FIG. 9, FIG. 15 shows the position of the output surface 54 d of the 36 scintillators 54 constituting the scintillator matrix 52 and the effective photoelectric area K of the entrance face plate 109. The relationship is schematically shown. As is clear from this figure, in the radiation detector 150 of the comparative example, as in the first and second embodiments, the scintillator 54 located on the outer peripheral portion of the scintillator matrix 52 is multi-layered. The anode-type photomultiplier tube 101 faces the peripheral portion of the cylindrical portion 112 via the peripheral portion of the incident face plate 109 of the anode type photomultiplier tube 101. In particular, the scintillators 54 located at the four corners of the scintillator matrix 52 pass through the four curved corners 109 b of the entrance face plate 109 of the multi-anod photomultiplier tube 101. And the four curved corners 1 1 2 b of the cylinder 1 1 2 are opposed to each other.

Here, in the comparative example, the outer diameter W c of the entrance face plate 109 and the outer diameter W c of the cylindrical portion 112 are the outer diameter W of the scintillator matrix 52 (for example, , 39 mm) and the thickness M of the magnetic shield 40 have the following relationship.

The outer diameter Wc of the entrance face plate 109 and the cylindrical portion 112 is equal to the outer diameter W of the scintillator matrix 52. The inner diameter Wc of the cylindrical portion 112 is smaller than the outer diameter Wc by twice the thickness Tc. Therefore, the outer diameter W of the scintillator matrix 52 is smaller by 2 × Tc.

When the radiation detector 150 of the comparative example having such dimensions is arranged so that the adjacent magnetic shields 40 are substantially in contact with each other, as shown in FIG. 17, Adjacent cylinders 1 1 2 are separated by an amount equal to the thickness M of the magnetic shield 40. Since the adjacent cylinders 1 1 and 2 need only be separated from each other by the minimum necessary space S, it can be seen that an extra (M−S) amount of dead space is generated. On the other hand, the outer diameter Wc of the entrance face plate 109 and the cylindrical portion 112 is equal to the outer diameter W of the scintillator matrix 52, and the inner diameter Wc of the cylindrical portion 112 is equal to the scintillator matrix. 5 Smaller than outer diameter W of 2. For this reason, as shown in FIG. 15, the output surface 54 d of the scintillator 54 located at the outer periphery of the scintillator matrix 52 has an effective photoelectric area K inside the cylinder head 17. The area of the part not facing is large. In addition, since the curvature radii R c and R c ′ of the curved corners 1 1 2 b are large, the output surface 54 d of the scintillator 54 located at the four corners of the scintillator matrix 52 is curved. The area of the part that is not opposed to the effective photoelectric region K inside the corner 1 1 2b is also large.

Thus, in the comparative example, the outer diameter Wc of the cylindrical portion 112 is equal to the outer diameter W of the scintillator matrix 52. On the other hand, in the first and second embodiments, as described above, the outer diameter W1 of the cylinder main body 13 is equal to the outer diameter W of the scintillator matrices 52, and the cylinder head 17 Outside diameter W 2 is larger than the outside diameter W of scintillator matrix 52. Therefore, the outer diameter W2 of the cylinder head 17 in the first and second embodiments is larger than the outer diameter Wc of the cylinder portion 112 of the comparative example. In addition, the inner diameter W 2 ′ of the cylinder head 17 in the first and second embodiments is larger than the inner diameter W c of the cylinder part 112 of the comparative example. Moreover, the radii of curvature R 2 and R 2 ′ of the curved corners 17 b of the cylinder head 17 in the first and second embodiments are the radii of curvature of the curved corners 1 12 b of the comparative example. Less than R c, R c '.

Hereinafter, the outer diameter W2 of the cylinder head 17 is made larger than the outer diameter Wc of the comparative example, the inner diameter W2 of the cylinder head 17 is made larger than the inner diameter Wc of the comparative example, and Department The first and second curvature radii R 2, R 2 ′ of the 17 curved corners 17 b are made smaller than the curvature radii 1 (:, R c ′ of the curved corners 1 1 2 13 of the comparative example. The excellent effects of the second embodiment will be described with reference to FIGS. 18 and 19.

FIG. 18 shows the area of the effective photoelectric region K of the multi-anode type photomultiplier tube 1 in the first and second embodiments in comparison with the area of the effective photoelectric region K in the comparative example. ing. Assuming that the area of the effective photoelectric region K of the comparative example is 100%, the area of the effective photoelectric region K is 110% in the first embodiment, and the effective photoelectric region K is 2% in the second embodiment. The area of K increases to 114%.

Thus, according to the multi-anode type photomultiplier tube 1 of the first and second embodiments, the area of the effective photoelectric region K can be made larger than that of the comparative example. In particular, in the case of the second embodiment, since the inner peripheral surface 17 i of the cylinder head 17 has a pincushion shape that is hollowed toward the curved corner 17 b, The area of the effective photoelectric region K inside the curved corner 17 b near the corner 17 b can be further increased.

FIG. 19 shows the relationship between the effective photoelectric area K of the first and second embodiments and the comparative example in FIG. 18 and the output surface 54 d of all the scintillators 54 of the scintillator matrix 52. The positional relationship is shown. The ratio (percentage) of the area of the portion of the output surface 54 d of each scintillator facing the effective photoelectric region K is hereinafter referred to as the scintillator effective area ratio. FIG. 19 shows values of the scintillator effective area ratios of four scintillators 54 located near one corner of the scintillator matrix 52.

As is clear from this figure, in the case of the comparative example, since the outer diameter Wc of the cylindrical portion 112 is equal to the outer shape W of the scintillator matrix 52, the scintillator The effective area ratio is remarkably low in the scintillator 54 located on the outer periphery of the scintillator matrix 52. Further, since the curvature radii Rc and Rc 'of the curved corners 112b are large, the scintillator effective area ratio is further reduced near the curved corners 112b. For this reason, in the comparative example, there is a large difference in sensitivity between the central portion of the scintillator matrix 52 and the peripheral portion, particularly, the corner portion.

On the other hand, according to the first embodiment, since the outer diameter W 2 of the cylinder head 17 is larger than the outer diameter W of the scintillator matrix 52, it is located on the outer periphery of the scintillator matrix 52. The scintillator effective area ratio in the scintillator 54 is higher than in the comparative example. In addition, since the curvature radii R2 and R2 'of the curved corner 17b are small, the scintillator effective area ratio near the curved corner 17b is significantly higher than that of the comparative example. Therefore, the sensitivity can be made substantially uniform between the center portion, the peripheral portion, and the corner portion of the scintillator matrix 52. In particular, according to the second embodiment, the effective area ratio of the scintillator near the curved corner 17b is further improved. Therefore, the sensitivity at the center, the periphery, and the corners of the scintillator matrix 52 can be made more uniform.

As described above, according to the first and second embodiments, the ratio of the area of the portion of the output surface 54 d of each scintillator 54 facing the photocathode 20 is determined for all scintillators 54. It can be a substantially uniform large value. For this reason, the photocathode 20 can receive the scintillation light from all the scintillators 54 at a substantially uniform ratio, and can detect radiation with a substantially uniform sensitivity.

It is assumed that the magnetic shield 40 is not provided in the multi-anode type photomultiplier tube 101 of the comparative example. Further, the outer diameter Wc of the cylindrical portion 112 of the comparative example is equal to the outer diameter W2 of the cylindrical head 17 in the first and second embodiments, that is, It is assumed that the value is larger than the outer diameter W of the scintillator matrix 52 by (M−S). In this case, as in the first and second embodiments, the radiation detectors 150 of the comparative example are arranged so that the adjacent scintillator matrices 52 are separated from each other by a space M. The adjacent cylinders 1 1 2 are separated from each other by a minimum space S. However, in the first and second embodiments, the radius of curvature R 2, R 2 ′ of the curved corner portion 17 b of the cylinder head 17 is the curvature radius R c of the curved corner portion 1 12 b of the comparative example. If it is smaller than R c ′, the area of the effective photoelectric region K can be made larger than that of the comparative example, and the scintillator effective area ratio in all scintillators can be made more uniform than that of the comparative example.

More specifically, the outer diameter W 2 of the cylinder head 17 in the first and second embodiments is equal to the outer diameter W c of the comparative example, and the ratio is smaller than the inner diameter W 2 of the cylinder head 17. Even if the inner diameter Wc of the comparative example is equal to the radius of curvature R2, R2 of the curved corner portion 17b of the cylinder head 17 in the first and second embodiments, the curved corner portion of the comparative example is the same. If the radius of curvature R c, R c ′ of 1 12 b is smaller, the area of the effective photoelectric region K in the first and second embodiments is, as shown in FIG. With respect to the area of K (100%), they are 104% and 108%, respectively. Further, as shown in FIG. 21, the scintillator effective area ratio near the curved corner 17b is higher in the first and second embodiments than in the comparative example.

The multi-anode type photomultiplier tube and radiation detector according to the present invention are not limited to the above-described embodiments, and various modifications and improvements can be made within the scope described in the claims.

For example, the shape of the incident face plate and the cross-sectional shapes of the cylinder head and the cylinder main body need not be substantially square as long as they are substantially square, and may be, for example, rectangular. The thickness of the cylinder head may be smaller than the thickness of the cylinder body.

In the first embodiment, even if the wall thickness T2 of the cylinder head 17 becomes slightly thinner near the curved corner 17b and the inner radius of curvature R2 'is slightly smaller than the outer radius of curvature R2. good. Similarly, the thickness T1 of the cylinder body 13 may be slightly reduced near the curved corner 13b, and the inner radius of curvature R1 'may be slightly smaller than the outer radius of curvature R1.

The multi-anode type photomultiplier tube is not limited to the 2 × 2 type, but may be any type in which an arbitrary number of dynode rows / anode electrodes are arranged.

Each dynode row is not limited to the line focus type and may be another type. A plurality of radiation detectors may be arranged not two-dimensionally but two-dimensionally or three-dimensionally.

The multi-anode type photomultiplier tube does not need to be provided with a magnetic shield. A multi-anode type photomultiplier tube may be used other than a radiation detector. Industrial applicability

The multi-anode type photomultiplier tube and radiation detector of the present invention can be widely used in various fields such as other radiation detection and other photodetection, in addition to being usable in the medical field as a Pozitron C-claw. it can.

Claims

The scope of the claims

1. Glass entrance face plate,

A hollow side tube made of glass connected to a surface on one side of the incident surface plate and extending along a tube axis substantially perpendicular to the incident surface plate;

A photoelectric surface for emitting photoelectrons according to the light incident on the incident surface plate is formed in a region of the one side surface of the incident surface plate located inside the side tube, and a plurality of the photoelectric surfaces are provided. In a multi-anode type photomultiplier tube in which a plurality of electron multipliers and a plurality of anode electrodes are provided inside the side tube corresponding to the region of

The side tube integrally includes a tube head, a funnel-shaped connecting portion, and a tube main body along the tube axis;

The tube main body has a hollow substantially quadrangular prism shape having four first curved corners, and extends along the pipe axis by a first length. A substantially vertical cross section having a first size, wherein the four first curved corners are each curved at a first radius of curvature;

The cylinder head has a hollow substantially quadrangular prism shape having four second curved corners, extends along the pipe axis by a second length, and is substantially parallel to the pipe axis of the cylinder head. A vertical section having a second magnitude, the four second curved corners each curving at a second radius of curvature, wherein the second length is shorter than the first length; A second magnitude is greater than the first magnitude, the second radius of curvature is smaller than the first radius of curvature,

The funnel-shaped connecting portion connects the cylinder head and the cylinder main body coaxially, the cylinder head is connected to the one surface of the incident face plate, and the photoelectric surface is connected to the incident surface. Formed in an area located on the one side of the face plate and inside the cylinder head, A multi-anode type photomultiplier tube, wherein the plurality of electron multipliers and the plurality of anode electrodes are provided inside the cylindrical main body.

2. The cylinder head has an outer peripheral surface and an inner peripheral surface,

The outer peripheral surface connects each two adjacent second curved corners in a substantially straight line, and the inner peripheral surface connects each two adjacent second curved corners in a curved line. Is gradually approaching the outer peripheral surface from the substantially center position between each two adjacent second curved corners toward each of the two second curved corners.

2. The multi-anod type photomultiplier according to claim 1, wherein:

3.

A focusing electrode plate for focusing photoelectrons emitted from the photocathode,

A partition plate for dividing an electron focusing space defined between the photoelectric surface and the focusing electrode plate into a plurality of segment spaces corresponding to a plurality of regions of the photoelectric surface.

Each electron multiplier receives photoelectrons focused by the focusing electrode plate in the corresponding segment space,

The partition plate extends from the cylinder head through the funnel-shaped connection portion to the cylinder main body in the side tube;

The focusing electrode plate, the plurality of electron multipliers, and the plurality of anode electrodes are arranged in the cylinder main body,

2. The multi-anod type photomultiplier tube according to claim 1, wherein a magnetic shield is provided on an outer periphery of the cylinder main body.

4. A plurality of scintillators are arranged in a two-dimensional matrix, each scintillator has an output surface, each scintillator generates scintillation light in response to radiation incident on the scintillator, and outputs the scintillation light. A scintillator matrix output from the surface, A multi-anode type photomultiplier tube for detecting scintillation light output from each scintillator of the scintillator matrix,

The multi-anode type photomultiplier tube,

An entrance face plate made of glass; and a hollow side tube made of glass connected to a surface on one side of the entrance face plate and extending along a tube axis substantially perpendicular to the entrance face plate. The surface opposite to the surface on the side of "1" "3" faces the output surface of all the scintillators of the scintillator trittas, and emits photoelectrons corresponding to the scintillation light incident on the incident surface plate. A photocathode is formed in a region located inside the side tube on the one side surface of the entrance face plate, and a plurality of electron multipliers and a plurality of anodes are provided corresponding to the plurality of regions of the photocathode. Electrodes are provided inside the side tube,

The tube main body has a hollow substantially quadrangular prism shape having four first curved corners, extends along the tube axis by a first length, and is substantially formed along the tube axis of the tube main body. A vertical cross section having a first dimension, wherein the four first curved corners are each curved at a first radius of curvature;

The funnel-shaped connection portion connects the cylinder head and the cylinder main body coaxially, the cylinder head is connected to the one surface of the incident face plate, and the photoelectric surface is connected to the input surface. Formed on an area located on the one side of the firing surface plate and inside the cylinder head,

A radiation detector, wherein the plurality of electron multipliers and the plurality of anode electrodes are provided inside the cylinder main body.