WO2005091332A1

WO2005091332A1 - Multianode electron multiplier

Info

Publication number: WO2005091332A1
Application number: PCT/JP2004/003860
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: JP4756604B2; JPWO2005091332A1

Abstract

A multianode electron multiplier has a glass container (5) containing a partition wall (9), a shield electrode (11), a first stage dynode (Dy1), a second stage dynode (Dy2), a dynode array (25) and an anode (31), wherein a photoelectric surface (3) is formed on the inside of an incident surface plate (4). The partition wall (9) has a cross shape and divides an electron convergence space into four segments. The shield electrode (11) is disposed to shield the second stage dynode (Dy2) from the photoelectric surface (3). The photoelectric surface, the partition wall and the shield electrode are applied with an identical potential. Electrons being emitted depending on the light impinging on the photoelectric surface enter the dynode efficiently regardless of the emission place and then they are multiplied and detected by means of the anode.

Description

Description Multi-anode photomultiplier tube Technical field

The present invention relates to a multi-anod type photomultiplier tube. Background art

'Japanese Unexamined Patent Application Publication No. 6-111711 (hereinafter referred to as Patent Document 1) describes a photomultiplier tube having N independent electron multipliers arranged around a central axis. I have. This photomultiplier tube has a symmetrical hermetic container with a long axis, and the photoelectrons are transferred to N electron multipliers according to the positions of photoelectrons generated from the photocathode formed on the 內 side surface of the hermetic 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, and the axis of symmetry substantially coincides with the long axis of the sealed container. '' The electron multiplier consists 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 an electrode including a portion corresponding to a first-stage dynode for multiplying the power by.

The part corresponding to the focusing electrode of the electrode and the part corresponding to the first stage dynode Are separated by flat plates. The flat plate has a hole corresponding 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 having a photocathode on the inner surface, and a cross-shaped convex portion provided with the same potential as the photocathode is provided between each channel.

Japanese Patent Application Laid-Open No. H11-250583 (hereinafter referred to as Patent Document 4) describes a photomultiplier tube in which the electron focusing space of the photomultiplier tube 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 arranged in the center near the bottom of the first-stage dynode. To adjust the electric field inside the photomultiplier tube, The electrons emitted from the photocathode and the secondary electrons emitted from the first-stage dynode are made to enter the first-stage dynode and the sheet-type multipliers of the second and subsequent stages.

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 wall.

In the photomultiplier described in Patent Document 3, in order to control the gain of a specific channel of the sheet-like dynode, a control electrode is provided between the sheets of the dynode, and the same potential as that of the photocathode is applied between the channels. With the cross-shaped projection, electrons are incident on the dynode.

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 above-described photomultiplier, depending on where the electrons on the photocathode emit electrons, the electrons may not efficiently enter the first-stage dynode. In particular, photoelectrons emitted from the periphery of the photocathode or secondary electrons emitted from the periphery of the first-stage dynode cannot pass through the first-stage dynode or the second-stage dynode and pass through. May be lost. In such a case, there arises a problem that the effective area of the photocathode is reduced and the substantial 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 to solve the above-mentioned problems has a glass incident surface plate, and is connected to a surface on one side of the incident surface plate, and extends along a tube axis substantially perpendicular to the incident surface plate. A hollow side tube made of glass extending therethrough; and a photoelectron corresponding to the light incident on the incident surface plate, formed in an area of the one side surface of the incident surface plate located inside the side tube. A photocathode, a partition wall extending a predetermined length in the tube axis direction from a boundary between a plurality of regions of the photocathode, and provided inside the side tube corresponding to the plurality of regions of the photocathode; A plurality of electron multipliers for multiplying photoelectrons emitted from the photocathode; and a plurality of electron multipliers provided inside the side tube corresponding to a plurality of regions of the photocathode and emitted from the electron multiplier. A plurality of anode electrodes for receiving electrons, wherein the electron multiplier is provided on the side tube side inside the side tube, and multiplies when photoelectrons emitted from the photoelectric surface enter. A first-stage dynode that emits secondary electrons; and a first-stage dynode that is provided inside the side tube on the tube shaft side. A second-stage dynode that further multiplies secondary electrons emitted from the second-stage dynode to emit secondary electrons, and is provided inside the side tube, and receives secondary electrons emitted from the second-stage dynode. And a plurality of dynodes that successively multiply and emit secondary electrons, and wherein between the second dynode and the photocathode, the second dynode is disposed with respect to the photocathode. A multi-anode type photomultiplier tube, wherein a shield electrode for shielding is provided, and the photoelectric surface, the partition wall, and the shield electrode are given the same potential.

In the above multi-anod type photomultiplier, the photocathode emits photoelectrons in response to incident light. The multi-anode type photomultiplier tube has a plurality of electron multipliers. A partition wall is provided over a predetermined length in a tube axis direction of the side tube from a portion corresponding to a boundary between the plurality of electron multipliers on the photocathode. The electron multiplier has a first-stage dynode, a second-stage dynode, and a plurality of dynodes. The first dynode is provided on the side tube side, and the second dynode is provided on the tube shaft side. Between the second dynode and the photocathode, a shield electrode for shielding the second dynode from the photocathode is provided. Provided. The photocathode, the partition wall, and the shield electrode are given the same potential to adjust the electric field in the side tube so that photoelectrons are efficiently incident on the first-stage dynode irrespective of the location of the photocathode.

A flat electrode having an opening for passing electrons toward the first dynode may be provided between the shield electrode and the second dynode. The opening may be provided with a conductive mesh member. It is preferable that the flat electrode can be supplied with a potential equal to or higher than the potential of the first dynode and lower than the potential of the second dynode.

According to the above configuration, the electric field generated between the photocathode and the first-stage dynode is adjusted, and the electrons emitted from the periphery of the photocathode are efficiently incident on the first-stage dynode. ·

Also, an electric field is generated between the first dynode and the second dynode so that the secondary electrons emitted from the first dynode are incident on the second dynode, so that the electrons are efficiently emitted. Can be incident.

Further, an opening may be provided in the shield electrode, and the electric field in the side tube may be adjusted in order to reduce a difference in traveling time until the electron emitted from the photocathode reaches the first dynode. Good.

With the above configuration, the time required to reach the first dynode is uniform, regardless of the position on the photocathode where electrons are generated.

Therefore, even at the periphery of the photocathode of the multi-anode type photomultiplier, electrons can be detected with a uniform sensitivity from the center without a time difference, and a clear image can be obtained when applied to image processing etc. become. Brief Description of Drawings

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

FIG. 5 is a diagram showing the trajectories of electrons when the shield electrode 11 is not provided in the multi-anod type photomultiplier tube 1 provided with the partition walls 9.

FIG. 6 is a diagram showing the electron trajectory of the multi-anod type photomultiplier tube 1 provided with the partition wall 9 and the shield electrode 11.

FIG. 7 is a diagram showing electron trajectories when the multi-anod type photomultiplier tube 1 has no partition wall 9 and no shield electrode 11.

FIG. 8 is a plan view and a schematic sectional view showing a multi-anod type photomultiplier tube 100 according to a second embodiment of the present invention.

FIG. 9 is a diagram showing a trajectory of electrons of a multi-anodic photomultiplier tube 100 provided with a partition wall 109 and a shield electrode 110. FIG.

FIG. 10 is a diagram showing the electron trajectory of the multi-anode type photomultiplier tube 200 provided with the partition wall 109 and the shield electrode 220. BEST MODE FOR CARRYING OUT THE INVENTION

A multi-anod type photomultiplier according to a first embodiment of the present invention 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 vapor-deposited on the upper inner surface 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 an armature 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 dynode Dy1, a second dynode Dy2, and a first screen 211, A second screen 22, a flat plate 23, a dynode row 25, an anode 31 and the like are provided. The first-stage dynode Dy1, the second-stage dynode Dy2, the vertical focusing 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, and is arranged below the partition 9 inside the glass container 5 so as to shield the second-stage dynode D y 2 from being exposed to the photocathode 3. ing. 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 that of 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 openings of the flat electrode 13 are provided at four locations around the center axis Z of the glass container 5 in two rows and two columns, and the photoelectric surfaces 3 corresponding to the respective segment spaces 5_1 to 5-4. _ Electrons emitted from 1 to 3-4 pass through.

The plate electrode 13 applies 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. Can be

A mesh 15 is provided in each opening of the flat electrode 13. The mesh 15 is a conductive mesh member. The mesh 15 is supplied with the same potential as the first-stage dynode Dy1 or a slightly higher potential than the potential of the first-stage dynode Dy1 within a range not exceeding the potential of the second-stage dynode Dy2. Can be A first-stage dynode Dy1 is provided below each mesh 15. That is, four first-stage dynodes D y1 are provided, one each for 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. Photocathode 3 corresponding to space 5-1 to 5-4 It is arranged in the vicinity of the side tube 6 inside the glass container 5 so that one to three to four are desired. The first-stage 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.

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 have an integrated back side of the vertical portion. Similarly, 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 dynode Dy1 and the second dynode Dy2 and the dynode array 25. As shown in FIG. 4, the screen focusing electrode 20 has a first screen 21, a second screen 22, a flat plate 23, and an opening 24.

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 arranged in each of the segment spaces 5-1 to 5-4 in the glass container 5, four in total. The first screen 21 preferably extends to the photocathode 3 side from the lower end of the first dynode Dy1. 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 1. Each of the dynodes is composed of a flat plate portion 26 and four dynode portions 27. The four dynodes 27 correspond to the four openings 24, and extend from the first stand 21 of the opening 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 is integrated with the flat plate portion 26 of the third dynode Dy3 such that the flat plate 23 is located above the dynode portion 27. A mesh electrode 29 is integrated with the flat plate portion 26 of the fourth to ninth dynodes Dy4 to Dy9 so as to be positioned 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 dynode D yl O is provided below the anode 31, and emits secondary electrons to the anode 31 side when electrons emitted from the ninth dynode Dy 9 are incident. . A Node 31 detects the electron emitted from the 10th dynode Dy10 when it is incident.

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

Photocathode 3, Partition wall 9, Shield electrode 11, Plate-on-plate electrode 13, Converging electrode 20, First-stage dynode Dy1, Second-stage dynode Dy2, Dynode row 25, and A predetermined voltage is applied to the 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 of the incident surface plate 4, any of the corresponding photoelectric surfaces 3-1 to 3_4 is reduced by the amount of incident light. Emit a corresponding amount of photoelectrons. The emitted photoelectrons are supplied to the partition wall 9 and shield electrode provided in the corresponding segment space.

11. The light is converged by the plate-like electrode 13 and the like, passes through the corresponding mesh 15 and enters the first-stage dynode Dy1.

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-stage 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 Dy2. At this time, the second screen 22 is provided so as to protrude from the lower end position of the second dynode Dy2, and the electric power discharged from the second dynode Dy2 is provided. Can be efficiently guided to the opening 24 of the vertical focusing electrode 20. 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 a multiple in the dynode train 25 and incident on the anode 31. The node 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, the convergence and multiplication of photoelectrons can be accurately performed without being affected by an external magnetic field.

Next, the effects of the partition 9 and the shield electrode 11 will be described with reference to FIGS.

FIG. 5 is a view showing the trajectories of electrons when the partition wall 9 is provided above the flat plate electrode 13 and the shield electrode 11 is not provided. (A) is a plan view of the multi-anode type photomultiplier tube 1 viewed from above, and (b) is a cross-sectional view taken along line AA ′ of (a). In FIG. 5, trajectories q and r of electrons emitted from the center of the photocathode 3-4 and the vicinity of the tube axis Z are incident on the first-stage dynode D y1. However, paying attention to the electron trajectory p, the electrons emitted from the peripheral edge of the side tube 6 of the photocathode 3-4 do not enter the first-stage dynode D y 1 but move toward the first screen 21. It has deviated. In this case, light at a portion corresponding to the peripheral portion on the side tube 6 side of the photocathode 314 cannot be detected efficiently. FIG. 6 is a diagram showing the trajectories of electrons when the partition wall 9 and the shield electrode 11 are provided above the flat plate electrode 13. (A) is a multi-anode FIG. 1B is a plan view of the photomultiplier tube 1 viewed from above, and FIG. 2B is a cross-sectional view taken along line AA in FIG. In FIG. 6, the electron trajectories p, q ', and r have all reached the first-stage dynode Dy1. Furthermore, secondary electrons emitted by the electrons incident on the first-stage dynode Dy1 also enter the second-stage dynode Dy2, pass through the opening 24, and enter the dynode array 25. Is possible.

Therefore, in this case, electrons can be efficiently incident on the first-stage dynode D y 1 irrespective of the incident position of light on the photocathode 3-4, and the electrons are incident almost uniformly over the entire surface of the photocathode 3 Light can be detected.

FIG. 7 shows, as a comparative example, the trajectories of electrons when the partition wall 9 and the shield electrode 11 were not provided. (A) is a plan view of the multi-anode type photomultiplier tube 1 as viewed from above, and (b) is a cross-sectional view taken along line AA ′ of (a). The trajectory P "of the electrons emitted from the side tube 6 of the photocathode 3-4 is toward the second screen 22 and the trajectories r" and q of the electrons from a position near the tube axis Z side. “” Collides with the electrode 13 on the flat plate, and cannot both enter the first-stage dynode Dy 1.

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. A cross-shaped partition wall 9 extends from the photocathode 3 in the direction of the tube axis Z, and a shield electrode 11 is provided so as to shield the second-stage dynode D y 2, and both have the same potential as the photocathode 3. Is applied. With the above configuration, electrons emitted in response to the light incident on the photocathode 3 are converted into electron multipliers such as the first-stage dynode Dy1 and the second-stage dynode Dy2 regardless of the radiation position on the photocathode 3. Can be efficiently incident on It becomes. As described above, since the light incident on the photocathode 3 is detected almost uniformly regardless of the incident position, it is possible to obtain a clear image when used in an image display device or the like.

Next, a multi-anode type photomultiplier 100 according to a second embodiment of the present invention will be described with reference to FIGS. 8 to 10. The same components as those of the multi-anod type photomultiplier tube 1 according to the first embodiment are denoted by the same reference numerals.

As shown in FIG. 8, the multi-anod type photomultiplier tube 100 is composed of a multi-anode type photomultiplier tube 1 with a partition wall 9 instead of a partition wall 9 and a shield electrode 11 with a shield electrode 11. 1 1 0 is provided.

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. 8, the partition wall 109 is a cross-shaped wall when viewed from above. Like the partition wall 9, the electron focusing space in the glass container 5 is divided into four segment spaces 5-1 to 5-4. Is divided into As shown in FIG. 8, the lower portion has an opening 108 between itself and the shield electrode 110. The partition wall 109 is given the same potential as the photocathode 3.

The shield electrode 110 is a conductive plate-shaped member, and is arranged 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 rising edge extending in the direction of the photocathode 3 in the illustrated example, thereby reinforcing the strength of the shield electrode 110. An opening 112 is provided at the center of the shield electrode 110. The opening 1 1 2 is rectangular when viewed from above. The shield electrode 110 is given the same potential as the photocathode 3.

Other configurations and operations are the same as those of the multi-anod type photomultiplier 1. Next, the effects of the partition wall 109 and the shield electrode 110 will be described with reference to FIG. 8 and FIG. (A) in Fig. 8 is a multi-anode type photoelectric converter. FIG. 2B is a plan view of the secondary tube 100 viewed from above, and FIG. 2B is a cross-sectional view taken along line AA of FIG.

As shown in FIG. 8, the multi-anode type photomultiplier tube 100 has an opening 1 08 below the partition wall 109 and an opening 1 12 for the shield electrode 110, The electric field strength near the tube axis Z is prevented from lowering. Therefore, the electron trajectories q 2 and r 2 are closer to the first stage dynode D y 1 from the photocathode 3 than the electron trajectories q ′ and r ′ of the multi-anode type photomultiplier tube 1 in FIG. The time difference until the light enters is small.

FIG. 9 is a diagram showing electron trajectories of a multi-anod type photomultiplier tube 100 having a partition wall 109 and a shield electrode 110 on the upper electrode 13 on a flat plate. (A) is a plan view of the multi-anode type photomultiplier tube 100 viewed from above, and (b) is a cross-sectional view taken along line A_A, (a).

FIG. 9 shows the trajectories s, t, and u of the electrons in the segment space 5-4 emitted from the photocathode 3-4 near the partition wall 109. As shown in the figure, even if the positions where the electrons are emitted from the photocathode 3 are different, the time difference between the electron trajectories s, t, and u before they enter the first-stage dynode Dy1 is small.

Therefore, according to the multi-anod type photomultiplier 100, electrons can be efficiently incident on the first-stage dynode D y1 irrespective of the incident position of light on the photocathode 3, and the photocathode It is possible to detect the incident light almost uniformly over the entire surface of 3 and to reduce the time difference until the light enters the first-stage dynode D y 1 irrespective of the incident position on the photocathode 3.

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 having a dynode array 25 and the like and an anode 31 are provided so that light incident on the photocathode 3 can be reflected by the electron multiplier. Multiplied and detected by node 31. A cross-shaped partition wall 109 extends from the photocathode 3 in the direction of the tube axis Z. A shield electrode 110 is provided below the cross-section partition wall 109, and the same potential as that of the photocathode 3 is applied to both. 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.

With the above configuration, electrons emitted from the photocathode 3 in response to the incident light are converted into electron multipliers such as the first-stage dynode Dy1 and the second-stage dynode Dy2 regardless of the radiation position on the photocathode 3. It is possible to make the light incident on the surface efficiently. .

In addition, 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 photoelectric surface 3 Regardless of the electron emission position above, the difference in the transit time of 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, by providing the opening 108 below the partition wall 109, the evaporation source (not shown) used for forming the photocathode 3 can be reduced to four segment spaces 5-1 to 5-4. It is only necessary to provide one part in the glass container 5 in common, and the number of parts can be reduced.

FIG. 10 shows a multi-anode type photomultiplier tube 200 as a modification of the second embodiment. FIG. 10 is a view showing a configuration of a multi-anode type photomultiplier tube 200 provided with a partition wall 109 and a shield electrode 210 on the upper electrode 13 on a flat plate, and shows a locus of electrons. . (A) is a plan view of the multi-anode type photomultiplier tube 200 viewed from above, and (b) is a cross-sectional view taken along line AA ′ of (a).

In FIG. 100, the seal of the multi-anod type photomultiplier tube 100 is shown. A shield electrode 210 is provided in place of the shield electrode 210. Other configurations are the same as those of the multi-anod type photomultiplier tube 100.

The shield electrode 210 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 210 is provided with a rising edge extending in the direction of the photocathode 3 in the example shown in the figure, so as to increase the strength of the shield electrode 210. An opening 2 12 is provided at the center of the shield electrode 2 10. When viewed from above, the opening 2 12 has an uneven shape in which the width of a portion near the center of each of the segment spaces 5-1 to 5-4 is wide. The shield electrode 210 is given the same potential as the photocathode 3.

FIG. 10 shows the trajectories s ′ and tu ′ of electrons in the segment space 5-4 emitted from the photocathode 3-4 near the partition wall 109. As shown in the figure, the positions of the electron trajectories s', t, and u, which are incident on the first-stage dynode Dy1, have smaller variations compared to the electron trajectories s, t, and u in FIG. However, the transit time difference is further reduced than in the multi-anod type photomultiplier tube 100, and the incident position on the first dynode Dy1 is also constant. Therefore, according to the multi-anod type photomultiplier tube 200, the segment space 5-1 to the segment space 5-1 to the opening portion 108 below the partition wall 109 and the opening portion 212 of the shield electrode 210 are formed. Since the electric field in 5-4 becomes even more uniform, the transit time difference between the electrons from the photocathode 3 to the first stage dynode D y 1 and the Variation in the incident position on the first-stage dynode D y 1 can be reduced. Therefore, when used in an image display device or the like, a clearer image can be obtained.

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

For example, the edges of the shield electrodes 11, 110, 210 may not have any rising edge. According to this, it is possible to reduce the amount of the material constituting the shield electrodes 11, 110, 210, and to reduce the cost. 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 grid or the like according to the arrangement of the regions.

The opening of the flat electrode 13 may not be provided with the mesh 15. Also, the vertical, horizontal, and oblique portions of the first-stage dynode Dyl and the second-stage dynode Dy2 need not be flat, and may have a curved structure.

It is not always necessary to provide the vertical focusing electrode 20. In addition, a flat screen focusing electrode without the first screen 21 and the second screen 22 may be provided.

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 almost below the first screen 21. Although the dynode train 25 has the third dynode Dy3 to the tenth dynode Dy10, the dynode train 25 may have a smaller or larger number of dynodes.

Also, the venetian blind type dynode array 25 has been described, but a dynode array of other laminated structure such as a fine mesh type or a microphone opening channel plate type 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. Industrial potential

The multi-anod type 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 according to light incident on the incident face plate; A partition extending from the boundary between the regions to a predetermined length in the pipe axis direction;

A plurality of electron multipliers provided inside the side tube corresponding to the plurality of regions of the photocathode, for multiplying photoelectrons emitted from the photocathode;

A plurality of anode electrodes provided inside the side tube corresponding to the plurality of regions of the photocathode and receiving electrons emitted from the electron multiplier;

With

The electron multiplier is

A first-stage dynode that is provided on the side tube side inside the side tube and that multiplies and emits secondary electrons when photoelectrons emitted from the photoelectric surface enter;

A second-stage dynode that is provided inside the side tube on the side of the tube axis and that, when secondary electrons emitted from the first-stage node enter, are further multiplied by two to emit secondary electrons;

A plurality of dynodes that are provided inside the side tube and that multiply 次 by one after another when secondary electrons emitted from the second-stage dynode enter to emit secondary electrons;

Has,

A shield electrode is provided between the second dynode and the photocathode to shield the second dynode from the photocathode;

The photoelectric surface, the partition wall and the shield electrode are provided with the same potential. Features a multi-anod type photomultiplier tube.

2. The flat electrode having an opening for passing electrons toward the first dynode is provided between the shield electrode and the second dynode. Multi-anod type photomultiplier tube.

3. The multi-anod photomultiplier according to claim 2, wherein a conductive mesh member is provided in the opening of the flat electrode.

4. The multi-anode according to claim 2, wherein the flat electrode is supplied with a potential higher than the potential of the first-stage dynode and lower than the potential of the second-stage dynode. A single-type photomultiplier tube.

5. The shield electrode has an opening for adjusting an electric field in the side tube in order to reduce a difference in traveling time until electrons emitted from the photocathode reach the first stage diode. The multi-anod type photomultiplier according to any one of claims 1 to 4, characterized in that: