JPH113677A - Electron multiplier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electron multiplying tube capable of effectively preventing noise generation. SOLUTION: In this electron multiplier 1, neighboring edge parts 12b, 13b are displaced from each other in the extending direction of verge parts 12, 13 in the whole circumference of the verge parts 12, 13 of dynodes 11 [n-stage side dynodes 11A, (n+1) stage side dynodes 11B], and a distance between the neighboring edge parts 12b, 13b is enlarged, whereby suppression of electric field discharge is achieved. Such a constitution enables further suppression of the electric field discharge with space between the dynodes 11 maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron multiplier in which electrons introduced into a vacuum vessel are multiplied by dynodes stacked in multiple stages.

[0002]

2. Description of the Related Art Conventionally, there is JP-A-6-314551 as a technique in such a field. The electron multiplier described in this publication has an electron multiplier disposed in a vacuum vessel, and the electron multiplier has a plate-like dynode having electron multiplier holes arranged in a matrix. Are stacked in multiple stages. Further, the dynodes are integrated by bonding two dynode thin plates and welding the corners (corners) of the dynode thin plates.
Each dynode is provided with a notch at the corner so as to avoid welding marks of the adjacent dynode,
It suppresses the electric field discharge caused at the welding site.

[0003]

However, since the conventional electron multiplier is configured as described above, there are the following problems. In other words, by providing the notches at the corners of the dynode, the electric field discharge at the welding site is suppressed, but the distance between the dynodes is 0.16-0.
Since it is formed as very narrow as 17 mm, electric field discharge is likely to occur between the edge portions provided at the edge portions of the adjacent dynodes, which hinders further suppression of noise generation.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and has as its object to provide an electron multiplier in which the suppression of noise generation is effectively prevented.

[0005]

According to a first aspect of the present invention, there is provided an electron multiplier including an electron multiplier including a plurality of dynodes stacked in a plurality of stages arranged in a vacuum vessel. In the pipe, the edges of the opposing dynodes are displaced from each other in the direction in which the edges extend in substantially the entire periphery of the edge of the adjacent dynode among the plurality of dynodes.

The inventors have found that an electric field discharge is generated between the adjacent dynodes and between the edge portions formed at the edges of the dynodes, and this is greatly related to the generation of noise. Therefore, the electron multiplier of the present invention focuses on the edge of the dynode, displaces adjacent edges mutually in the direction in which the edges extend, and increases the distance between the adjacent edges, Suppression of electric field discharge was achieved. With this configuration, it is possible to further suppress the electric field discharge without increasing the interval between the dynodes.

In this case, the side of the adjacent dynode is
It is preferable to displace each other in the direction in which the edges extend. When such a configuration is adopted, the electron multiplier has a simple configuration in which the side surfaces of adjacent dynodes are alternately arranged.

It is preferable that the side surfaces of the respective dynodes are formed as tapered surfaces in the same direction, and the outermost peripheral lines of the respective dynodes are aligned in a line in the axial direction of the vacuum vessel. When such a configuration is employed, the electron multiplier can increase the interval between adjacent edge portions even if the side surfaces of the dynodes are aligned in a straight line. In addition, the positions of the side surfaces of the dynodes in the vacuum vessel can be aligned substantially all around.

Further, each dynode is formed by two dynode thin plates, and the side surface of the first dynode thin plate among the dynodes and the side surface of the second dynode thin plate among the dynodes extend in the direction in which the edge extends. It is preferable to displace each other. When such a configuration is adopted, the electron multiplying section can be provided with a step at the edge of each dynode, and the edges can be aligned in the same shape.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of an electron multiplier according to the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a sectional view showing the whole of an electron multiplier according to the present invention. The electron multiplier shown in FIG. 1 is a photomultiplier that converts weak light into electrons and multiplies the electrons. This photomultiplier tube 1 has a cylindrical metal side tube 2 whose both ends are open, and a glass light receiving surface plate 3 for receiving incident light is fixed to one open end of the side tube 2. A disc-shaped stem 5 on which a plurality of stem pins 4 are arranged is fixed to the other open end. And side tube 2
The light receiving face plate 3 and the stem 5 constitute a vacuum vessel 6, and an electron multiplier 7 is arranged inside the vacuum vessel 6.

On the inner side of the vacuum vessel 6, the light receiving face plate 3
A photoelectric conversion surface (photocathode) 8 made of a GaAs semiconductor crystal is provided on the back surface of the semiconductor device, and a focusing electrode 9 is arranged between the photoelectric conversion surface 8 and the electron multiplier 7. Therefore, the trajectory of the electrons emitted from the photoelectric conversion surface 8 is converged by the influence of the focusing electrode 9, and enters the predetermined area of the electron multiplier 7.

The electron multiplier 7 has a configuration in which plate-like dynodes 11 having electron multiplier holes 10 arranged linearly are stacked in multiple stages. Below the stacked dynodes 11, a final dynode 1 that reflects the multiplied electrons is provided.
2 and the final stage dynode 12 and dynode 11
Between them, an anode 13 for receiving electrons is arranged. The dynode 11, the last dynode 12, and the anode 13 are connected and fixed to the respective stem pins 4.

As shown in FIGS. 2 to 4, the square dynode 11 has two types of dynodes 11A and 11B. When the dynode 11A is an n-stage dynode, the dynode 11B is located on the (n + 1) -stage dynode. Dynode. The n-stage dynode 11A has a plurality of electron multiplier holes 10A arranged linearly, and all the electron multiplier holes 10A
The n-stage side dynode 11A has a wide edge 12 over the entire circumference. On the other hand, the (n + 1) th stage dynode 11B has a plurality of electron multiplier holes 10B arranged linearly,
0B, the n + 1-stage dynode 11B
Has a narrow edge 13 over its entire circumference. In the dynodes 11A and 11B, the side surface 12a of the edge portion 12 and the side surface 13a of the edge portion 13 are formed at right angles to the surface 12c of the edge portion 12 and the surface 13c of the edge portion 13 over the entire circumference. I have.

The electron multiplier 7 is assembled so that the electron multiplier hole 10A of the n-stage dynode 11A and the electron multiplier hole 10B of the (n + 1) -stage dynode 11B face each other. Side 12a of edge 12
Protruding outward, and the (n + 1) th stage dynode 11B
The side surface 13a of the edge portion 13 of FIG.
As a result, the edge 12 of the n-stage dynode 11A and n + 1
When comparing the edge portion 13 of the step-side dynode 11B, the edge portion 12b of the edge portion 12 and the edge portion 13b of the edge portion 13 obliquely face each other, and the opposing edge portions 12b and 13b
Can be displaced from each other in the direction in which the edges 12 and 13 extend.

As described above, the same type of n-stage dynode 11
By simply alternately stacking A and the n + 1-stage dynode 11B of the same type, the distance between the adjacent edge portions 12b and 13b can be increased, and the electric field discharge occurring between them can be suppressed. Further, the distance between the dynodes 11 is set to 0.16 to 0.17 mm as in the conventional electron multiplier.
It is possible to further suppress the electric field discharge while maintaining the minute space.

In consideration of the electrical connection between each dynode 11A, 11B and each stem pin 4, the dynode 11
Sides 12a, 13 of edges 12, 13 in A, 11B
a is provided with ears (not shown) projecting toward the side, that is, dynodes 11A and 11A.
When part of the side surfaces 12a and 13a is interrupted by ears on the outer periphery of B, the electric field discharge between the edge of the ear and the edge of the edge adjacent to the ear is negligible. Small. This is because the edge portion of the edge portion is formed to be much longer than the edge portion of the ear portion.

In the above embodiment, the n-stage dynode 11A is integrated by bonding two dynode thin plates A and B and welding the dynode thin plates A and B. Similarly, the (n + 1) th stage dynode 11B
Also, the dynode thin plates C and D are integrated.

Another embodiment of the electron multiplier according to the present invention will be described. The configuration other than the dynode 21 described later is the same as that of the photomultiplier tube 1 described above, and a description thereof will be omitted.

As shown in FIGS. 5 to 8, the square dynode 21 includes two types of dynodes 21A and 21B. When the dynode 21A is an n-stage dynode, the dynode 21B is located on the (n + 1) -stage dynode. Dynode. The n-stage dynode 21A has a plurality of electron multiplying holes 20A linearly arranged.
, The n-stage dynode 21A has an edge 22 over the entire circumference. In contrast, n +
The first-stage dynode 21B has a plurality of electron multiplier holes 20B linearly arranged, and the (n + 1) -stage dynode 21B extends over the entire circumference so as to surround all the electron multiplier holes 20B. It has an edge 23.

The side surface 22a of the edge 22 and the edge 23
Is formed as a tapered surface having a predetermined angle with respect to the surface 22c of the edge 22 and the surface 23c of the edge 23. In this case, the side surfaces 22a and 23a are formed as tapered surfaces at acute angles to the surface 22c of the edge 22 and the surface 23c of the edge 23.

Then, when the electron multiplier 7A is assembled so that the electron multiplier hole 20A of the n-stage dynode 21A and the electron multiplier hole 20B of the (n + 1) -stage dynode 21B face each other, the n-stage dynode 21A The outermost peripheral line 22d of the side surface 22a and the outermost peripheral line 23d of the side surface 23a in the (n + 1) th stage dynode 21B are aligned in a line along the direction of the tube axis L of the side tube 2 (see FIG. 1).
As a result, the edge 22 of the n-stage dynode 21A and n + 1
When comparing the edge 23 of the step-side dynode 21B, the edge 22b of the edge 22 and the edge 23b of the edge 23 are obliquely opposed to each other, and the opposing edges 22b and 23b are opposed to each other.
Can be displaced from each other in the direction in which the edges 22 and 23 extend. In addition, since the edge portion 22b is formed with an obtuse angle, electrons are less likely to be emitted at this portion, and electric field discharge between the adjacent edge portions 22b and 23b can be efficiently suppressed. it can.

As described above, the side surface 22 of the dynode 21A
a and the side surface 23a of the dynode 21B are parallel and aligned along the direction of the tube axis L.
The interval between 2b and 23b can be increased. In addition, the positions of the side surface 22a of the dynode 21A and the side surface 23a of the dynode 21B can be aligned substantially all around in the vacuum vessel 6. The n-stage dynode 21A is integrated by bonding two dynode thin plates A1 and B1 and welding the dynode thin plates A1 and B1. Similarly, the (n + 1) th stage dynode 21B is also integrated by the dynode thin plates C1 and D1.

A further embodiment of the electron multiplier according to the present invention will be described. The configuration other than the dynode 31 described later is the same as that of the photomultiplier tube 1 described above, and the description thereof is omitted.

As shown in FIGS. 9 to 12, the square dynode 31 has two types of dynodes 31A and 31B.
When the dynode 31A is a dynode on the n-th stage, the dynode 31B is a dynode on the n + 1-th stage. The n-stage dynode 31A has a plurality of electron multiplying holes 30A linearly arranged.
The n-stage dynode 31A has an edge 32 over the entire circumference so as to surround A. Similarly, the (n + 1) th stage dynode 31B has a plurality of electron multiplier holes 30B linearly arranged, and the (n + 1) th stage dynode 31B is provided around the entire periphery thereof so as to surround all the electron multiplier holes 30B. It has an edge 33 over it.

The n-stage dynode 31A is integrated by bonding the first dynode thin plate A2 and the second dynode thin plate B2 and welding the dynode thin plates A2 and B2. In this case, without arranging the side surface 32aA of the first dynode thin plate A2 and the side surface 32aB of the second dynode thin plate B2 on the same surface, specifically, the side surface 32aA of the first dynode thin plate A2 and the second The side surfaces 32aB of the second dynode thin plate B2 are shifted from each other. Then, the side surface 32aA of the first dynode thin plate A2 protrudes outward, and the side surface 32aB of the second dynode thin plate B2 retracts inward. Similarly, n + 1
The step-side dynode 31B is also integrated by the dynode thin plates C2 and D2, and the side surface 33a of the first dynode thin plate C2 is formed.
C protrudes outward, and the second dynode thin plate D2
Side surface 33aD is drawn inward.

The electron multiplier 7B is assembled so that the electron multiplier hole 30A of the n-stage dynode 31A and the electron multiplier hole 30B of the (n + 1) -stage dynode 31B face each other. Side 32a and n +
The side surface 33a of the first-stage dynode 31B is aligned in a line along the direction of the tube axis L of the side tube 2 (see FIG. 1). As a result, when comparing the edge 32 of the n-stage dynode 31A and the edge 33 of the (n + 1) th dynode 31B, the edge 32b of the edge 32 and the edge 33b of the edge 33 face in an oblique direction. The opposing edges 32b and 33b can be displaced from each other in the direction in which the edges 32 and 33 extend.

As described above, the side surface 32 of the dynode 31A
a and the side surface 33a of the dynode 31B
Even if aligned along the direction, adjacent edge portions 32b,
The space between 33b can be made large, and electric field discharge between adjacent edge portions 32b and 33b can be suppressed. Moreover, the side surface 3 of the dynode 31A in the vacuum vessel 6
The positions of 2a and the side surface 33a of the dynode 31B can be aligned substantially all around.

The present invention is not limited to the various embodiments described above.
It may be a mesh type dynode. Although the photoelectric conversion surface (photocathode) 8 does not need to be a GaAs semiconductor crystal, the GaAs type photoelectric conversion surface 8 has a small effective area and can form a wide edge of the dynode. It is easy to devise the side. In the above-described embodiment, the photomultiplier tube having the photoelectric conversion surface has been described. However, an electron multiplier tube having no photoelectric conversion surface may be used.

[0030]

As described above, the electron multiplier according to the present invention has the following effects. That is, by displacing the edges of the opposing dynodes in the direction in which the edges extend in substantially the entire periphery of the edge of the adjacent dynode among the plurality of dynodes, It is possible to effectively suppress the electric field discharge generated between them, and effectively prevent the noise from being generated.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing one embodiment of an electron multiplier according to the present invention.

FIG. 2 is an enlarged perspective view of a main part of an electron multiplier applied to the electron multiplier of FIG.

FIG. 3 is a sectional view taken along the line III-III in FIG. 2;

FIG. 4 is a plan view of a dynode applied to the electron multiplier of FIG. 2;

FIG. 5 is an enlarged perspective view of a main part showing a modification of the electron multiplier.

FIG. 6 is a sectional view taken along the line VI-VI in FIG. 5;

FIG. 7 is a plan view of a dynode applied to the electron multiplier of FIG.

FIG. 8 is a bottom view of the dynode shown in FIG. 7;

FIG. 9 is an enlarged perspective view of a main part showing another modification of the electron multiplier.

FIG. 10 is a sectional view taken along line XX in FIG. 9;

11 is a plan view of a dynode applied to the electron multiplier of FIG.

FIG. 12 is a bottom view of the dynode shown in FIG. 11;

[Explanation of symbols]

1: Electron multiplier (photomultiplier), 6: vacuum vessel, 7,
7A, 7B: electron multiplier, 11, 21, 31 ... dynode, 11A, 21A, 31A ... n-stage dynode, 11
B, 21B, 31B... N + 1 stage side dynodes, 12, 1
3, 22, 23, 32, 33 ... edge, 12a, 13a,
22a, 23a... Side surfaces of dynodes, 12b, 13b,
22b, 23b: edge portion, 23d: outermost peripheral line, 3
2aA, 33aC: Side surface of first dynode thin plate, 32
aB, 33aD: Side surface of the second dynode thin plate, A2
C2: first dynode sheet, B2, D2: second dynode sheet.

Claims (4)

[Claims] 1. An electron multiplier comprising an electron multiplier comprising a plurality of dynodes stacked in a plurality of stages disposed in a vacuum vessel, wherein an edge of an adjacent dynode of the plurality of dynodes is provided. An electron multiplier wherein substantially opposite edges of the dynodes are displaced from each other in an extending direction of the edge. 2. The electron multiplier according to claim 1, wherein the side surfaces of the adjacent dynodes are mutually displaced in the extending direction of the edge. 3. The method according to claim 1, wherein the side surfaces of the dynodes are formed as tapered surfaces in the same direction, and the outermost peripheral lines of the dynodes are aligned in a line in the axial direction of the vacuum vessel. Electron multiplier. 4. Each of the dynodes is formed of two dynode thin plates, and a side of a first one of the dynodes and a side of a second one of the dynodes are formed by the dynode. 2. The electron multiplier according to claim 1, wherein the electron multipliers are displaced from each other in a direction in which the edges extend.