WO2005091333A1

WO2005091333A1 - Photomultiplier

Info

Publication number: WO2005091333A1
Application number: PCT/JP2004/003855
Authority: WO
Inventors: Suenori Kimura; Takayuki Ohmura; Teruhiko Yamaguchi; Masuo Ito
Original assignee: Hamamatsu Photonics K.K.
Priority date: 2004-03-22
Filing date: 2004-03-22
Publication date: 2005-09-29
Also published as: JPWO2005091333A1

Abstract

A photomultiplier comprising a screen convergence electrode (20) disposed between a first stage dynode (Dy1) and a second stage dynode (Dy2) and a plurality of third and subsequent stage dynodes. The screen convergence electrode has a first screen (21), a second screen (22), a flat plate (23) and an opening. The first screen is disposed on the first stage dynode side of the opening to extend toward the photoelectric plane side beyond the lower end of the first stage dynode. The second screen is disposed on the second stage dynode side of the opening to extend toward the photoelectric plane side beyond the lower end of the second stage dynode. Electrons being emitted depending on light incident to the photoelectric plane (3) can thereby impinge efficiently on each dynode at an electron multiplying section regardless of the emitting position on the photoelectric plane and thereby the light incident to the photoelectric plane can be detected substantially uniformly regardless of the incident position.

Description

Description Photomultiplier tube

Technical field

The present invention relates to a photomultiplier tube. Background art

Japanese Patent Application Laid-Open No. 6-111757 (hereinafter referred to as Patent Document 1) describes a photomultiplier tube having N independent electron multipliers arranged around a central axis. . This photomultiplier tube has a closed container with a symmetrical structure having a long axis, and the photoelectrons are transferred to N electron multipliers according to the positions of the photoelectrons generated from the photocathode formed on the inner surface of the closed container. A first stage dynode is provided for separation.

The first stage dynode is cup-shaped with a flat bottom and a side surface extending toward the photocathode, with the axis of symmetry approximately coinciding with the long axis of the enclosure. The electron multiplier is composed of a sheet type electron multiplier. In addition, an electrode having substantially the same potential as that of the photocathode is arranged in a central portion near the bottom of the first-stage dynode.

JP-A-7-192686 (hereinafter referred to as Patent Document 2) describes a photomultiplier tube having at least two segment spaces. This photomultiplier tube has a closed container having a photocathode formed on the inside of the front surface, and a portion corresponding to a converging electrode for converging photoelectrons emitted from the photocathode is provided in the closed container. And a portion corresponding to a first-stage dynode for multiplying the power.

The portion corresponding to the focusing electrode of the electrode and the portion corresponding to the first stage dynode are separated by a flat plate. The flat plate corresponds to each segment space And a grid is provided in the hole. A central partition wall is provided in a direction including the plane including the central axis of the sealed container and in a direction opposite to the photocathode from the flat plate. The second and subsequent input dynodes are provided near the photovoltaic surface of the central partition wall. A horizontal bar is located in the center of the closed container, including the central axis, parallel to the plate and slightly away from it. The horizontal bar is insulated from the electrode and given a potential equal to or close to that of the photocathode.

Japanese Patent Application Laid-Open No. 8-30635 (hereinafter referred to as Patent Document 3) describes a multi-channel electron multiplier. This electron multiplier has a sheet-like dynode, and a control electrode is provided between the sheets of the dynode in order to control the gain of a specific channel.

This multi-channel electron multiplier has a closed container provided with a photocathode on the inner surface, and a cross-shaped ώ portion provided with the same potential as the photocathode is provided between each channel.

Japanese Patent Application Laid-Open No. H11-250853 (hereinafter referred to as Patent Document 4) describes a photomultiplier in which the electron focusing space of a photomultiplier is divided into a plurality of segments by a partition plate. . In this photomultiplier tube, a partition plate extends from near a photocathode formed on the inner surface of the sealed container to a direction including a central axis of the sealed container. The partition plate is given the same potential as the photocathode. Each segment has multiple dynodes to multiply electrons. Disclosure of the invention

In the photomultiplier tube described in Patent Document 1, the shape of the first-stage dynode is cup-shaped, and an electrode having substantially the same potential as the photocathode is provided at the center near the bottom of the first-stage dynode. To adjust the electric field in the photomultiplier tube, and the electrons emitted from the photocathode and the secondary emitted from the first stage dynode Electrons enter the first stage dynode and the second and subsequent sheet-type multipliers.

The photomultiplier described in Patent Literature 2 includes an electrode serving also as a focusing electrode and a first-stage dynode, and allows electrons emitted from the photocathode to be incident on the first-stage dynode. Secondary electrons emitted from the dynode are incident on the second and subsequent input dynodes due to the potential difference between the first dynode and the second and subsequent input dynodes and the action of the central partition.

In the photomultiplier tube described in Patent Document 3, in order to control the gain of a specific channel of a sheet-like dynode, a control electrode is provided between dynode sheets, and a photocathode is provided between each channel. Electrons are made incident on the dynode with a cross-shaped projection provided with the same potential.

In the photomultiplier tube described in Patent Document 4, a partition plate having the same potential as the photocathode is arranged between a plurality of segments, and an electron is incident on the dynode by adjusting an electric field in the photomultiplier tube. .

However, in the photomultiplier tube as described above, there are cases where electrons are not efficiently incident on the first-stage dynode depending on the place where electrons are emitted from the photocathode. In particular, photoelectrons emitted from the periphery of the photocathode or secondary electrons emitted from the periphery of the first-stage dynode cannot enter the first-stage dynode or the second- and subsequent-stage dynodes. In some cases, the effective area of the photocathode is reduced, and the actual detection sensitivity is reduced. In addition, the output signal in the photocathode is not uniform, and particularly when used for image processing or the like, there is a problem that a peripheral image cannot be obtained clearly.

Means for Solving the Problems The present invention made in order to solve the above-mentioned problem has a glass incident surface plate, and a glass incident surface plate connected to one surface of the incident surface plate and extending along a tube axis substantially perpendicular to the incident surface plate. A hollow side tube; and a surface on the one side of the entrance face plate A photocathode formed in a region located inside the side tube and emitting photoelectrons according to light incident on the incident face plate; an electron multiplier for multiplying photoelectrons emitted from the photocathode; An anode electrode provided inside the side tube corresponding to the photocathode and receiving an electron emitted from the electron multiplier section; and the electron multiplier section provided inside the side tube. A first-stage dynode that multiplies and emits secondary electrons when the photoelectrons emitted from the photocathode are incident; and inside the side tube, at substantially the same position as the first-stage dynode in the axial direction. A second-stage dynode that is further arranged to multiply and emit secondary electrons when secondary electrons emitted from the first-stage dynode are incident; and a first-stage dynode that is provided inside the side tube. And the second stage dynode is provided at a lower portion in the pipe axis direction, and When secondary electrons emitted from the two-stage dynode are incident, they are multiplied one after another to emit secondary electrons. A flat plate having an opening desired by the two-stage dynode and provided between the second-stage dynode and the third-stage dynode; and the opening extending toward the photocathode side from a lower end of the first-stage dynode. A first screen provided on the first dynode side of the second dynode, and a first screen provided on the second dynode side of the opening so that a tip is located above a lower end of the second dynode. A converging electrode having a second screen extending to the photocathode side; and a photomultiplier tube comprising:

In the photomultiplier, the photocathode emits photoelectrons in response to incident light. The electron multiplier has a first stage dynode, a second stage dynode, a plurality of stages of dynodes below the third stage dynode, and a focusing electrode. When the electrons emitted from the photocathode are incident on the first stage, secondary electrons are emitted. When the electrons emitted from the first dynode enter, the second dynode multiplies and emits secondary electrons. The focusing electrode has a flat plate with an opening through which electrons from the second stage dynode pass, A first screen is provided on the first dynode side, and a second screen is provided on the second dynode side of the opening. The focusing electrode adjusts the potential near the first-stage dynode and the second-stage dynode, and the potential between the second-stage dynode and the third-stage dynode to efficiently transfer electrons to each stage dynode. It is made to be incident on.

Also, the present invention provides a glass incident surface plate, a glass hollow side tube 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 which is formed in an area of the one side surface of the face plate located inside the side tube and emits photoelectrons in accordance with light incident on the incident surface plate; and a photoelectron emitted from the photoelectric surface. And an anode electrode provided inside the side tube corresponding to the photocathode and receiving electrons emitted from the electron multiplier. A first stage dynode provided inside the side tube, for multiplying and emitting secondary electrons when photoelectrons emitted from the photocathode enter, and a first dynode inside the side tube; A secondary dynode disposed at substantially the same position as the stage dynode in the axial direction and emitted from the first stage dynode A second-stage dynode that further multiplies when electrons enter and emits secondary electrons; and a first dynode and a second-stage dynode at the lower part in the tube axis direction inside the side tube. A plurality of dynodes, including a third dynode and a third dynode, which sequentially multiply and emit secondary electrons when secondary electrons emitted from the second dynode are incident; and the first dynode. A first screen extending from the lower end of the first dynode to the photocathode side than a lower end of the first dynode, and a notch for making the third dynode desired by the second dynode. A flat plate, and a second screen provided at the lower end of the second dynode of the cut portion and extending toward the photocathode side from the lower end of the second dynode. The first stage die is fixed by being fixed between the third stage die node. Over de and the third-stage dynode And a focusing electrode forming an opening extending to between the photomultiplier and a photomultiplier tube.

In the above-mentioned photomultiplier tube, a focusing electrode composed of a first screen and a second screen plate, an opening force S formed by fixing the focusing electrode, The potential is adjusted so that electrons can efficiently enter the dynodes in each stage.

Also, the present invention provides a glass incident surface plate, a glass hollow side tube 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 which is formed in an area of the one side surface of the face plate located inside the side tube and emits photoelectrons in accordance with light incident on the incident surface plate; and a photoelectron emitted from the photoelectric surface. And an anode electrode provided inside the side tube corresponding to the photocathode and receiving electrons emitted from the electron multiplier. A first stage dynode provided inside the side tube, for multiplying and emitting secondary electrons when photoelectrons emitted from the photocathode enter, and a first dynode inside the side tube; The secondary die released from the first stage die is disposed at substantially the same position in the axial direction as the stage die node. When the electron enters, it multiplies further and emits secondary electrons.

A second-stage dynode, and a secondary electron emitted from the second-stage dynode is provided inside the side tube below the first-stage dynode and the second-stage dynode in the tube axis direction. Then, a plurality of dynodes below the third dynode, which multiply one after another to emit secondary electrons, and the photocathode provided at the lower end of the first dynode more than the lower end of the first dynode A first screen extending to the side, a first opening for making the third stage dynode desired to the second stage dynode, and a first opening between the first stage dynode and the third stage dynode. A flat plate provided between the second-stage dynode and the third-stage dynode, and a flat plate provided at a lower end side of the second-stage dynode of the first opening. A focusing electrode having a second screen extending from the lower end of the second dynode to the photocathode side.

In the above-described photomultiplier tube, a focusing electrode comprising a first screen and a second screen flat plate and having a first opening and a second opening is provided by an electron multiplier. The potential of the section is adjusted so that electrons can efficiently enter the dynodes of each stage.

The focusing electrode is preferably provided with a potential higher than the second-stage dynode and equal to or lower than the third-stage dynode. With this configuration, the electrons emitted from the second stage dynode efficiently enter the third stage dynode while being converged by the focusing electrode.

The present invention further provides a glass entrance face plate, a glass hollow side tube 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. A photoelectron surface which is formed in an area of the one side surface of the face plate located inside the side tube and emits photoelectrons according to light incident on the incident face plate; and a photoelectron emitted from the photocathode. And an anode electrode provided inside the side tube corresponding to the photoelectric surface and receiving electrons emitted from the electron multiplier. A first dynode that is provided inside the side tube and that multiplies and emits secondary electrons when photoelectrons emitted from the photocathode are incident; and a first stage dynode inside the side tube. The dynode is disposed at substantially the same position in the axial direction as the A second-stage dynode that emits secondary electrons by multiplying by a factor of two when the next electron is incident; and a first dynode and a second-stage dynode provided inside the side tube below the tube axis. A plurality of dynodes below the third dynode, which sequentially multiply and emit secondary electrons when secondary electrons emitted from the second dynode are incident; and the first dynode. A first focusing electrode provided at the lower end of the node and above the third dynode, and a first focusing electrode provided at the lower end of the second dynode and above the third dynode. And the electron multiplied by the second stage dynode passes through the space between the first focusing electrode and the second focusing electrode. A photomultiplier tube characterized by being incident on a dynode.

In the photomultiplier tube, the first focusing electrode and the second focusing electrode adjust the potential of the electron multiplier, and electrons from the second-stage dynode communicate with the first focusing electrode. Electrons are efficiently incident on the dynodes of each stage by passing through the space between the second focusing electrode and entering the third dynode.

In any of the above-described photomultiplier tubes, the first focusing electrode and the second focusing electrode may be formed of the same member. Brief Description of Drawings

FIG. 1 is a schematic cross-sectional view of the multi-anod type photomultiplier tube 1 according to the first embodiment of the present invention, taken along plane AA ′ of FIG.

FIG. 2 is a plan view of the multi-anod type photomultiplier tube 1 as viewed from above.

FIG. 3 is a cross-sectional view of the multi-anod type photomultiplier tube 1 taken along a plane C-C ′ in FIG.

FIG. 4 is a top view of the vertical focusing electrode 20 of the multi-anod type photomultiplier tube 1.

FIG. 5 is a diagram showing a trajectory of electrons in the multi-anod type photomultiplier tube 1.

Fig. 6 shows the machine without the first screen 21 and the second screen 22. FIG. 2 is a view showing a trajectory of electrons of a multi-anode type photomultiplier tube 1;

FIG. 7 is a diagram showing the electron trajectory when the mesh 24 is provided in the multi-node anode photomultiplier tube 1 without the first screen 21 and the second screen 22. FIG.

FIG. 8 is a diagram showing the electron trajectory of the multi-anode type photomultiplier tube 1 when the second screen 22 is not provided.

FIG. 9 is a cross-sectional view taken along line AA ′ of FIG. 10 of the multi-anod type photomultiplier tube 100 according to the second embodiment of the present invention.

FIG. 10 is a plan view of the multi-anod type photomultiplier tube 100 viewed from above.

FIG. 11 is a cross-sectional view of the multi-anod type photomultiplier tube 100 taken along the line C-C 'in FIG.

FIG. 12 is a top view of the focusing electrode 120 of the multi-anod type photomultiplier tube 100. FIG.

FIG. 13 is a view showing a trajectory of electrons in the multi-anode type photomultiplier tube 100.

FIG. 14 is a top view of the screen electrode 220 of the multi-anod type photomultiplier tube 100. FIG. BEST MODE FOR CARRYING OUT THE INVENTION

As an example of a photomultiplier tube of the present invention, a multi-node photomultiplier tube 1 according to a first embodiment will be described with reference to the drawings.

First, the configuration of the multi-anode type photomultiplier 1 will be described with reference to FIGS. 1 to 4. FIG. As shown in FIG. 1, the multi-anode type photomultiplier tube 1 is a 2 × 2 multi-anode type photomultiplier tube. The multi-node photomultiplier tube 1 has a substantially rectangular prism-shaped glass container 5. The The glass container 5 is made of transparent glass. The upper surface of the glass container 5 in FIG. 1 is a light incident surface plate 4.

The incident surface plate 4 has a photoelectric surface 3 formed inside. The side surface of the glass container 5 extends along a tube axis Z substantially perpendicular to the entrance face plate 4, and forms a hollow side tube 6. Input / output pins 35 are provided on the bottom 7 of the glass container 5. The entrance face plate 4, the side tube 6, and the bottom 7 are integrally formed to seal the inside of the glass container 5.

An aluminum-thin film 7 is deposited on the inner surface of the upper part of the side tube 6 of the glass container 5, and is given the same potential as the photoelectric surface 3. The outer surface of the side tube 6 of the glass container 5 is provided with a magnetic shield (not shown) made of a magnetic material such as permalloy, and is covered with a tube made of a resin or the like.

Inside the glass container 5, there are a partition 9, a shield electrode 11, a plate electrode 13, a mesh 15, a first-stage dynode Dyl, a second-stage dynode Dy2, a vertical focusing electrode 20, and a dynode array. 25, anode 31 and so on. The first-stage dynode Dyl, the second-stage dynode Dy2, the convergence electrode 20 and the dynode array 25 correspond to an electron multiplier.

The photocathode 3 inside the glass container 5, the shield electrode 11, the flat electrode 13, the first dynode Dy1, the second dynode Dy2, the dynode row 25, the anode 31, etc. It is connected to the output pin 35 by a wiring (not shown) and given a predetermined potential.

The partition 9 is made of a conductive member and extends from the photocathode 3 in the direction of the tube axis Z. As shown in FIG. 2, the partition wall 9 is a cross-shaped wall when viewed from above, and divides the electron focusing space in the glass container 5 into four segment spaces 5-1 to 5-4. As shown in FIG. 1, the lower part is connected to the shield electrode 11. The partition 9 is given the same potential as the photocathode 3.

The shield electrode 11 is a conductive plate-like member, A second dynode D y 2 is arranged below the wall 9 to shield the second dynode D y 2 from being exposed to the photocathode 3. The periphery of the shield electrode 11 is provided with a rising extending in the direction of the photocathode 3 in the example shown in the figure, thereby reinforcing the strength of the shield electrode 11. The shield electrode 11 is given the same potential as the photocathode 3.

The plate-like electrode 13 has an opening as shown in FIG. 2, and is provided below the shield electrode 11 so as to cover the cross section of the glass container 5. A rising portion extending in the direction of the photocathode 3 is provided around the flat electrode 13. In the illustrated example, the opening of the plate-like electrodes 1 3 provided in two rows and two columns four positions around the central axis Z of the glass container 5, each segment space 5 1 to ₅ - the photocathode 3 corresponding to the 4 — Electrons emitted from 1 to 3_4 pass through.

The plate electrode 13 has the same potential as the first-stage dynode Dy1 or a potential slightly higher than the potential of the first-stage dynode Dy1 within a range not exceeding the potential of the second-stage dynode Dy2. Is given.

A mesh 15 is provided in each opening of the flat electrode 13. The mesh 15 is a conductive mesh member. The mesh 15 has the same potential as the first-stage dynode Dy1 or a potential slightly higher than the potential of the first-stage dynode Dy1 within a range not exceeding the potential of the second-stage dynode Dy2. . A first-stage dynode Dy1 is provided below each mesh 15. That is, four first-stage dynodes Dy1 are provided, one each in each of the segment spaces 5-1 to 5_4 in the glass container 5. The first-stage dynode D y 1 includes a horizontal portion extending horizontally and flat, a vertical portion extending flat in the axial direction, and a beveled portion connecting the horizontal portion and the vertical portion and extending obliquely. The photocathode 31 corresponding to the spaces 5-1 to 5-4 is disposed near the side tube 6 inside the glass container 5 so as to desire the photocathode 3 1 to 3-4. ing. The first dynode D y1 is given a potential higher than the photocathode 3 and lower than the anode 31.

The second-stage dynode D y 2 includes a horizontal portion extending horizontally and flat, a vertical portion extending flat in the axial direction, and a beveled portion connecting the horizontal portion and the vertical portion and extending obliquely. The first-stage dynode D y1 is arranged near the axis Z inside the glass container 5 as desired. That is, each of the segment spaces 5-1 to 5-4 in the glass container 5 is provided with four second-stage dynodes Dy2, one each.

Out of the four second-stage dynodes Dy2, the two second-stage dynodes Dy2 in the segment space 5-1 and the segment space 5-2 are integrated on the back side of the vertical part. Similarly, the two second-stage dynodes Dy2 of segment space 5-3 and segment space 5-4 are integrated on the back side of the vertical part. The second-stage dynode Dy2 is given a potential higher than the first-stage dynode Dyl and lower than the anode 31.

A vertical focusing electrode 20 is provided between the first-stage dynode Dy1 and the second-stage dynode Dy2 and the dynode array 25. The convergence electrode 20 is provided with a potential higher than the second-stage dynode Dy2 and equal to or lower than the third-stage dynode Dy3, preferably the same potential as the third-stage dynode Dy3. As shown in FIG. 4, the screen focusing electrode 20 has a first screen 21, a second screen 22, a flat plate 23, an opening 24, and the like.

The openings 24 are arranged in two rows and two columns at four positions around the axis Z, where the second-stage dynode Dy2 is desired. At the end of the opening 24 on the first dynode Dy1 side, a first screen 21 extending in the direction of the photocathode 3 is provided. The first screen 2 1 is disposed in each of the segment spaces 5-1 to 5-4 in the glass container 5, one in each of the four spaces. The first screen 21 preferably extends to the photocathode 3 side from the lower end of the first dynode Dy1. That's right.

At the end of the opening 24 on the second dynode Dy2 side, a second screen 22 extending in the direction of the photocathode 3 is provided. The second screen 22 is arranged in each of the segment spaces 5-1 to 5-4 in the glass container 5, one for each, a total of four. The second screen 22 extends above the lower end of the second dynode Dy2.

The dynode array 25 is a venetian blind dynode in the multi-anodic photomultiplier tube 1. The dynodes at each stage include a flat plate portion 26 and four dynode portions 27. The four dynode portions 27 correspond to the four openings 24, and extend from the first stand 21 of the openings 24 to the side pipe 6 side.

Each of the dynode portions 27 of the dynode row 25 is provided with a plurality of electrode elements 28. In the third, fifth, seventh and ninth-stage dynodes Dy3, Dy5, Dy7 and Dy9, the electrode element 28 is connected to the tube so that its secondary electron emission surface desires the second-stage dynode. It is arranged at an angle of 45 degrees with respect to the axis Z. The electrode elements 28 of the 4th, 6th and 8th dynodes Dy4, Dy6 and Dy8 are the 3rd, 5th, 7th and 9th dynodes Dy3, Dy5, Dy7 and Dy Nine electrode elements 28 are arranged at an angle of 45 degrees with respect to the tube axis Z in the opposite direction.

The flat plate 23 of the vertical focusing electrode 20 is integrated with the flat plate 26 of the third dynode Dy3 so as to be located above the dynode 27. The mesh electrode 29 is integrated with the flat plate portion 26 of the fourth to ninth dynodes Dy4 to Dy9 so as to be located above the electrode element 28.

The anodes 31 are provided below the ninth dynode Dy9 so as to correspond to the four dynodes. The 10th stage dynode D y 10 is When the electrons emitted from the ninth-stage dynode Dy9 are incident, secondary electrons are emitted to the anode 31 side. Node 31 detects when an electron emitted from the 10th dynode Dy10 is incident.

The multi-anode type photomultiplier 1 having the above structure operates as follows.

Photocathode 3, Partition wall 9, Shield electrode 11, Plate electrode 13, Standing focus electrode 20, First stage dynode Dyl, Second stage dynode Dy2, Dinode row 25, etc. A predetermined voltage is applied to the transfer node 31 via the input / output pin 35.

When light enters the area corresponding to any one of the segment spaces 5-1 to 5-4 in the incident surface plate 4, any of the corresponding photoelectric surfaces 3-1 to 3-4 becomes smaller than the amount of incident light. Emit a corresponding amount of photoelectrons. The emitted photoelectrons are converged by the partition wall 9, shield electrode 11 and plate electrode 13 provided in the corresponding segment space, pass through the corresponding mesh 15 and enter the first stage dynode D yl .

The first-stage dynode D y 1 emits secondary electrons according to the incident photoelectrons. The secondary electrons are focused by the vertical focusing electrode 20 and are incident on the second dynode Dy2.

At this time, since the first screen 21 extends above the lower end position of the first-stage dynode Dy1, the position of the equipotential line of the first-stage dynode Dy1 is raised upward, The position of the equipotential line on the second dynode Dy2 is set to a position closer to the horizontal part than the diagonal part of the second dynode Dy2, and most of the vertical part and the diagonal part are the secondary electron emission region. It can be.

The electrons emitted from the second-stage dynode Dy2 go to the third-stage dynode Dy3 which is given a higher potential than the second-stage dynode DV2. this At this time, the second screen 22 is provided so as to protrude above the lower end position of the second dynode Dy2, so that electrons emitted from the second dynode Dy2 can be efficiently focused on the vertical focusing electrode 20. Can be led to the opening 24.

The electrons passing through the opening 24 enter the third-stage dynode Dy3. The third-stage dynode Dy3 extends to the side tube 6 side from the opening 24, and the electrons passing through the opening 24 can be efficiently incident. The electrons are sequentially multiplied by multiple stages in the dynode train 25 and incident on the anode 31. The anode 31 generates a signal corresponding to the incident electrons and outputs the signal as an output signal to the outside of the glass container 5 via the input / output pin 35.

In the multi-anode type photomultiplier tube 1, the shield electrode 11, the flat plate electrode 13, the vertical focusing electrode 20, the first dynode Dy1, the second dynode Dy2, and the dynode row 25 , And the anode 31 are disposed inside the glass container 5, and a magnetic shield is provided on the outer periphery. Therefore, convergence and multiplication of photoelectrons can be accurately performed without being affected by an external magnetic field.

Next, the effect of the vertical focusing electrode 20 will be described with reference to FIGS. 5 to 8.

FIG. 5 is a diagram showing a trajectory of electrons in the multi-anod type photomultiplier tube 1. In the multi-anod type photomultiplier tube 1, the first screen 2 1 and the second screen 2 2 are higher than the second stage dynode D y 2 together with the flat plate 23, and the third screen dynode D y 3 or less. Potential, preferably the same potential as the third stage dynode Dy3, the first stage dynode Dy1 to the second stage dynode Dy2, and the second stage dynode Dy2 to the third stage It controls the trajectory of electrons to dynode D y 3. For this reason, the electron trajectories p 0, q 0, r 0, and s 0 are incident on the respective trajectories without deviating from the first-stage dynode Dy 1 and the second-stage dynode Dy 2 as shown. Looking at the trajectory of electrons emitted after being incident on the second-stage dynode D y 2, the electron trajectory r O collides with the first screen 21 after being emitted from the second-stage dynode D y 2 are doing. That is, the light that has entered the position of the electron trajectory r O is not detected by the anode 31. The electron trajectories p 0, q 0, and s 0 are incident on the third-stage dynode D y 3 and further incident on the fourth-stage dynode D y 4.

Therefore, in the multi-anode type photomultiplier tube 1, the detection efficiency of the light incident on the periphery of the photocathode is slightly reduced, but the detection of the incident light can be generally performed satisfactorily.

As a comparative example, FIG. 6 shows the trajectories of electrons in the case where the first screen 21 and the second screen are not provided. In FIG. 6, the electron trajectories p 1, q 1, r 1, and s 1 are due to the light that has entered the electron trajectories p 0, q 0, r 0, and s 0 at almost the same position as the photocathode 3-1. It is a trajectory of emitted electrons.

As shown in FIG. 6, without the first screen 2 1 and the second screen 2 2, the electron trajectories pl, ql, rl, and si are the electron trajectories p 0, q 0, r 0, The position of incidence on the second-stage dynode Dy2 is shifted toward the photocathode as compared to s0. In addition, since the electric field from the third dynode Dy3 is weak, the negative potential of the first dynode Dy1 on the second dynode Dy2 is strong, and the electron trajectories p1, q1 Thus, there are many secondary electrons that cannot escape from the second-stage dynode Dy2. Therefore, the light incident on the photocathode 3 cannot be detected efficiently.

As a second comparative example, FIG. 7 does not have the first screen 21 and the second screen, the opening 24 of the flat plate 23, the first dynode Dy1, and the third dynode. The trajectory of electrons when a mesh 34 is provided in the portion corresponding to D y 3 is shown. In FIG. 7, the electron trajectories p 2, q 2, r 2, and s 2 correspond to the electron trajectories p 0, q 0, r 0, s O and the photocathode 3-1. It is a trajectory of an electron emitted by light incident on the same position.

As shown in FIG. 7, the first screen 21 and the second screen 22 are formed and the trajectories p2, q2, r2, and s2 of the electrons are the trajectories p1, q of the electrons. Similar to 1, r 1 and s 1, the position of incidence on the second dynode D y 2 moves toward the photocathode as compared to the electron trajectories p 0, q 0, r 0 and s 0. Also, since the electric field from the third-stage dynode Dy3 is weak, the negative potential of the first-stage dynode Dy1 on the second-stage dynode Dy2 is strong, as shown by the electron trajectories p2 and q2. Therefore, there are many secondary electrons that cannot escape from the second-stage dynode Dy2.

Furthermore, since the mesh 3 4 is attached to the third dynode Dy3, the secondary electrons emitted from the third dynode Dy3 are not affected by the negative potential of the first dynode Dy1, The electron trajectories r 2 and s 2 no longer enter the fourth-stage dynode D y 4. Therefore, the light incident on the photocathode 3 can hardly be detected.

As a third comparative example, FIG. 8 shows an electron trajectory without the second screen 22. In Fig. 8, the electron trajectories p3, q3, r3, and s3 are emitted by light incident on the photocathode 3-1 at approximately the same position as the electron trajectories p0, q0, r0, and s0. FIG.

As shown in FIG. 8, the electron trajectories p 3, q 3, r 3, and s 3 also show the position of incidence on the second-stage dynode D y 2 even when there is no second screen 22. It is almost the same position as the traces p 0, q 0, r 0, s 0. However, secondary electrons emitted from the second-stage dynode D y 2 are attracted to the plate 23 below the first screen 21 and the first-stage dynode D y 1, and the electron trajectory q 3, As in r 3 and s 3, it collides with the first screen 2 1. Therefore, the number of electrons incident on the third dynode Dy3 decreases, so that light incident on the photocathode 3 cannot be detected efficiently. As described above, in the multi-anodic photomultiplier tube 1 according to the first embodiment, the first-stage dynode Dy1, the second-stage dynode Dy2, the dynode An electron multiplier having columns 25 and the like and an anode 31 are provided. Light incident on the photocathode 3 is multiplied by the electron multiplier and detected by the anode 31.

In addition, an opening 24 for making the third dynode Dy3 desired by the second dynode is provided, and a flat plate 23 provided between the second dynode Dy2 and the third dynode Dy3 is provided. A first screen 21 provided on the first dynode Dy1 side of the opening 24 and extending toward the photocathode 3 side from the lower end of the first dynode Dy1; A second screen provided on the second-stage dynode Dy2 side, the second screen extending to the photocathode 3 side such that the tip is located above the lower end of the second-stage dynode Dy2; A focusing electrode 20 is provided to give an electric potential higher than the second-stage dynode Dy2 and equal to or lower than the third-stage dynode Dy3.

With the above configuration, the electrons emitted in response to the light incident on the photocathode 3 are converted into the first dynode Dy1, the second dynode Dy2, and the third dynode D regardless of the radiation position on the photocathode 3. It is possible to efficiently enter the electron multiplier such as y3. As described above, since the light incident on the photocathode 3 is detected almost uniformly regardless of the incident position, a clear image can be obtained when used in an image display device or the like.

Next, a multi-anode photomultiplier 100 according to a second embodiment of the present invention will be described with reference to FIGS. 9 to 13. FIG. The same components as those of the multi-anod type photomultiplier 1 according to the first embodiment are denoted by the same reference numerals.

As shown in FIGS. 9 to 12, the multi-anode type photomultiplier tube 100 is a partition wall 10 instead of the partition wall 9 of the multi-anod type photomultiplier tube 1. Is replaced by a vertical focusing electrode 20, and a vertical focusing electrode 120 is provided. A shield electrode 11 is replaced by a shield electrode 110.

The partition wall 109 is made of a conductive material and extends from the photocathode 3 in the direction of the tube axis Z. As shown in FIG. 10, the partition wall 109 is a cross-shaped wall when viewed from above. Like the partition wall 9, the electron converging space in the glass container 5 is divided into four segment spaces 5-1 to 5-4. Divided. The lower part of the partition wall 109 forms an opening 108 with the shield electrode 110. The partition wall 109 is given the same potential as the photocathode 3.

As shown in FIG. 10, the shield electrode 110 is a conductive plate-shaped member, and is disposed below the partition wall 109 inside the glass container 5 and above the flat plate electrode 13. . The periphery of the shield electrode 110 is provided with a rise extending in the direction of the photocathode 3 in the illustrated example, and the strength of the shield electrode 110 is enhanced. An opening 112 is provided at the center of the shield electrode 110. The shape of the opening 1 1 2 when viewed from above is rectangular. The shield electrode 110 is given the same potential as the photocathode 3.

The screen focusing electrode 120 has a first screen 21, a second screen 22, and a flat plate 123 as shown in FIG. By fixing the vertical focusing electrode 12 0 between the second-stage dynode Dy2 and the third-stage dynode Dy3, as shown in FIG. 9, the first-stage dynode Dy1 and the third An opening 144 is formed extending to between the step dynode Dy3. That is, the back surface of the first-stage dynode Dy1 faces the electron incident surface of the third-stage dynode Dy3.

The first screen 21 and the second screen 22 have the same configuration as the multi-anod type photomultiplier tube 1. Like the standing focus electrode 20, the standing focus electrode 1 20 is higher than the second-stage dynode Dy2, is equal to or lower than the third-stage dynode Dy3, and preferably has the same potential as the third-stage dynode Dy3. Is given. Other configurations and operations are the same as those of the multi-anod photomultiplier tube 1. Next, referring to FIGS. 5 and 13, the vertical focusing in the multi-anode photomultiplier tube 100 will be described. FIG. 5 illustrates the effect of the electrode 120. FIG. 5 shows the trajectory of electrons in the multi-anod type photomultiplier tube 1. The force S, as described in the first embodiment, The trajectory r 0 collides with the first screen 21 and does not enter the third-stage dynode D y 3 and is not detected by the node 31. Further, even if the secondary electrons emitted from the third-stage dynode Dy3 are incident on the third-stage dynode Dy3, the secondary electrons are not affected by the negative potential of the first-stage dynode Dy1. It may re-enter the stage dynode D y 3. In addition, since there is no influence of the negative potential of the first-stage dynode Dy1, there is also a case where the third-stage dynode Dy3 jumps and enters the fourth-stage dynode Dy4 (the locus s0). The trajectory from the third-stage dynode Dy3 to the fourth-stage dynode Dy4) means that the secondary electron transit time between the dynodes takes a long time, and the time characteristics deteriorate.

In FIG. 13, the electron trajectories p 4, q 4, r 4, and s 4 correspond to the electron trajectories p 0, q O, r O, and s 0, which are incident on the light incident on the same position of the photoelectric surface 3-1 The trajectory of the more emitted electrons is shown. Here, a partition 9 is provided in place of the partition 109 to show the effect of the vertical focusing electrode 120.

In the multi-anod photomultiplier tube 100, an opening 144 wider than the opening 24 in the multi-anod photomultiplier tube 1 is provided, and the first-stage dynode D y1 and the third-stage Because of the opening between the dynode Dy3, the electron trajectories p4, q4, r4, and s4 all enter the third dynode Dy3, and the fourth dynode immediately below it. It is incident on D y 4. Therefore, the secondary electron transit time between the second-stage dynode Dy2 and the fourth-stage dynode Dy4 becomes faster, so that the time characteristics are improved as compared with the multi-anode type photomultiplier tube 1. . As described above, in the multi-anod type photomultiplier tube 100 according to the second embodiment, the first-stage dynode Dy1 and the second-stage dynode Dy2 are placed in the glass container 5. An electron multiplier section 31 having a dynode array 25 and the like is provided, and the light incident on the photocathode 3 is multiplied by the electron multiplier section and detected by the anode 31.

An opening 108 is provided between the partition wall 109 and the shield electrode 110, and an opening 112 is provided in the shield electrode 110. Further, the second dynode is desirably provided with a third dynode D y3, and an opening 144 extending between the first dynode Dy1 and the third dynode Dy3 is provided. A plate 1 23 provided between the stage dynode Dy2 and the third stage dynode Dy3, and a lower end of the first stage dynode Dy1 from below the lower end of the first stage dynode Dy1 Is also provided on the second dynode Dy2 side of the opening 144, with the tip located above the lower end of the second dynode Dy2. And a second converging electrode 120 having a second screen 22 extending toward the photocathode 3 side so as to be higher than the second dynode Dy2 and less than or equal to the third dynode Dy3. Potential.

With the above configuration, the electrons emitted in response to the light incident on the photocathode 3 emit the first dynode Dy1, the second dynode Dy2, and the third dynode irrespective of the radiation position on the photocathode 3. It is possible to efficiently enter the electron multiplier such as the de Dy3. Further, the electric field in the segment spaces 5-1 to 5-4 becomes more uniform due to the opening 1108 below the partition wall 109 and the opening 111 of the shield electrode 110, so that the Irrespective of the electron emission position on the surface 3, the transit time difference of the electrons from the photocathode 3 to the first stage dynode Dy1 can be reduced. Therefore, when used in an image display device or the like, a clear image can be obtained. Further, openings 1 4 2 are formed by the first dynode D y1 and the third dynode D y 3, and secondary electrons from the second-stage dynode D y 2 do not jump over the third-stage dynode D y 3 and enter the fourth-stage dynode D y 4. The time characteristic in detection is further improved.

As described above, the light incident on the photocathode 3 is detected almost uniformly regardless of the incident position, and the time characteristic is good, so that when used in an image display device or the like, a clear image can be obtained. .

As described above, the preferred embodiment of the photomultiplier according to the present invention has been described with reference to the accompanying drawings, but the present invention is not limited to the above-described embodiment. Those skilled in the art can make various modifications and improvements within the scope of the technical idea described in the claims.

For example, as shown in FIG. 14 instead of the screen focusing electrode 1 20 shown in FIG. 12, the screen 1 shown in FIG. 2. An opening 144 and an opening 124 may be formed and fixed between the second dynode Dy2 and the third dynode Dy3.

Instead of the focusing electrode 2 0, 1 2 0 or 2 2 0, at the lower end of the first-stage dynode D y 1 and above the third-stage dynode D y 3, A first converging electrode for converging secondary electrons, and a secondary electrode for the third-stage dynode Dy3 at the lower end of the second-stage dynode Dy2 and above the third-stage dynode Dy3. A second focusing electrode for converging electrons may be provided. The first focusing electrode and the second focusing electrode may be integrally formed by the same member, or may be independently formed by different members. The edges of the shield electrodes 11 and 110 do not need to rise. The shape of the opening provided in the shield electrode 110 is not limited to a rectangle. Also, the shield electrodes 11 and 110 need not always be provided. According to this, the amount of the material constituting the shield electrodes 11 and 110 can be reduced, and the cost can be reduced. The number of segment spaces 5-1 to 5-4 is not limited to four, but may be, for example, 3 × 3 9 spaces. At that time, the partition walls 9 are provided in a lattice shape or the like according to the arrangement of the regions.

It is not necessary to provide the mesh 15 in the opening of the flat electrode 13. The vertical, horizontal, and oblique portions of the first-stage dynode Dy1 and the second-stage dynode Dy2 do not have to be flat, and may have a curved structure.

The third-stage dynode Dy3 does not have to extend from the first screen 21 to the side pipe 6 side, but may extend to a substantially lower side of the first screen 21. Although the dynode row 25 has the third-stage dynode Dy3 to the tenth-stage dynode Dy10, the dynode row 25 may have a smaller or larger number of dynode rows.

Also, the venetian blind type is described as the dynode array 25, but a dynode array of another laminated structure such as a fine mesh type, a microphone opening channel plate type, or the like may be used. Instead of a stacked type, a box type or line focus type dynode may be provided as a dynode below the third stage dynode.

The glass container 5 has a substantially square pillar shape, but is not limited to this, and may be, for example, a cylindrical shape.

Although the multi-anode type photomultiplier tube 100 has the partition wall 109, the partition wall 109 may be replaced with the partition wall 9.

In the above-described embodiment, the photomultiplier according to the present invention has been described by taking as an example a multi-anod type photomultiplier 1, 100 having four segment spaces 5_1 to 5-4. The present invention is not limited to this, and can be applied to a photomultiplier tube having only one segment space. In that case, it is preferable that the third or lower dynodes are provided to the outside of the opening 24 or 124. Industrial potential

The photomultiplier according to the present invention can be widely used in various fields such as other radiation detection and other light detection, in addition to being usable as a positron CT in the medical field.

Claims

The scope of the claims

1. Glass entrance face plate,

A hollow glass side tube 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 photocathode formed in an area of the one side surface of the incident face plate located inside the side tube, for emitting photoelectrons corresponding to light incident on the incident face plate; and a photocathode emitted from the photocathode. An electron multiplier for multiplying the photoelectrons

An anode electrode provided inside the side tube corresponding to the photoelectric surface and receiving electrons emitted from the electron multiplier;

With

The electron multiplier is

A first-stage dynode provided inside the side tube and multiplying to emit secondary electrons when photoelectrons emitted from the photoelectric surface enter;

Inside the side tube, it is arranged at substantially the same position as the first stage dynode in the axial direction, and when secondary electrons emitted from the first stage dynode enter, further multiply to emit secondary electrons A second stage dynode,

Inside the side tube, provided below the first stage dynode and the second stage dynode in the axial direction of the tube, when secondary electrons emitted from the second stage dynode are incident, they are successively. A multi-stage dynode below the third dynode that multiplies and emits secondary electrons;

An opening for allowing the third dynode to be provided to the second dynode; a flat plate provided between the second dynode and the third dynode; and a first dynode of the opening. A first screen extending from the lower end of the first stage node toward the photocathode side; a second screen side of the opening having a second end connected to the second stage node; A focusing electrode having a second screen extending toward the photocathode side so as to be located above a lower end of the step dynode; A photomultiplier tube comprising:

2. The entrance face plate made of glass,

A photocathode formed in an area of the one side surface of the incident face plate located inside the side tube, for emitting photoelectrons corresponding to light incident on the incident face plate; and a photocathode emitted from the photocathode. Electron multiplier that multiplies the photoelectrons

With

The electron multiplier is

Inside the side tube, it is arranged at substantially the same position as the first stage dynode in the axial direction, and when secondary electrons emitted from the first stage dynode are incident, the secondary electrons are further multiplied by 增 to emit secondary electrons. A second stage dynode,

Inside the side tube, provided below the first-stage dynode and the second-stage dynode in the axial direction of the tube, and successively multiplied when secondary electrons emitted from the second-stage dynode enter. Dynodes below the third dynode that emit secondary electrons

A first screen provided on a lower end side of the first stage dynode and extending to the photocathode side from a lower end of the first stage dynode; and making the third stage dynode desired by the second stage dynode. A flat plate provided with a cut portion, and a second screen provided at a lower end side of the second stage die of the cut portion and extending toward the photoelectric surface side from a lower end of the second stage die. Being fixed between the second-stage dynode and the third-stage dynode, the first-stage dynode and the third-stage dynode are fixed. A focusing electrode forming an opening extending to a third stage dynode; and a photomultiplier tube.

3. Glass entrance face plate,

An anode electrode provided inside the side tube corresponding to the photocathode and receiving electrons emitted from the electron multiplier;

With

The electron multiplier is

Inside the side tube, it is arranged at substantially the same position as the first-stage dynode in the axial direction, and when secondary electrons emitted from the first-stage dynode enter, are further multiplied to generate secondary electrons. A second stage dynode that emits,

Inside the side tube, provided below the first stage dynode and the second stage dynode in the axial direction of the tube, multiplying sequentially when secondary electrons emitted from the second stage dynode enter. Dynodes below the third dynode that emit secondary electrons

A first screen provided at a lower end side of the first stage dynode and extending to the photocathode side from a lower end of the first stage dynode; and the third dynode is desired to the second dynode. A first opening, and a second opening between the first dynode and the third dynode, provided between the second dynode and the third dynode. A flat plate and a second stage die of the first opening A focusing electrode provided at the lower end of the node, the second dynode extending from the lower end of the second dynode toward the photocathode;

A photomultiplier tube comprising:

4. The photomultiplier according to any one of claims 1 to 3, wherein the focusing electrode is provided with a potential higher than the second-stage dynode and equal to or lower than the third-stage dynode. tube.

5. Glass entrance plate,

With

The electron multiplier is

Inside the side tube, it is arranged at substantially the same position as the first stage dynode in the axial direction, and when secondary electrons emitted from the first stage dynode are incident, they are further multiplied to generate secondary electrons. A second stage dynode that emits,

Inside the side tube, the first stage dynode and the second stage dynode are provided at a lower part in the tube axis direction, and when the secondary electrons emitted from the second stage dynode enter, they increase one after another. A multi-stage dynode below the third dynode that doubles and emits secondary electrons;

At the lower end of the first stage dynode and above the third stage dynode A first focusing electrode that can be

A second focusing electrode provided at a lower end of the second dynode and above the third dynode;

And the electron multiplied by 增 in the second stage node passes through the space between the first focusing electrode and the second focusing electrode and enters the third stage node. A photomultiplier tube characterized by emitting light.

6. The photomultiplier tube according to claim 5, wherein the first focusing electrode and the second focusing electrode are formed of the same member.