CN110571124A - First-stage dynode and photomultiplier - Google Patents
First-stage dynode and photomultiplier Download PDFInfo
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- CN110571124A CN110571124A CN201910486094.0A CN201910486094A CN110571124A CN 110571124 A CN110571124 A CN 110571124A CN 201910486094 A CN201910486094 A CN 201910486094A CN 110571124 A CN110571124 A CN 110571124A
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- 239000002184 metal Substances 0.000 claims description 8
- 239000006185 dispersion Substances 0.000 description 19
- 238000010586 diagram Methods 0.000 description 16
- 230000000052 comparative effect Effects 0.000 description 13
- 238000004088 simulation Methods 0.000 description 10
- 239000000463 material Substances 0.000 description 4
- 229910001220 stainless steel Inorganic materials 0.000 description 4
- 239000010935 stainless steel Substances 0.000 description 4
- 238000013459 approach Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000011521 glass Substances 0.000 description 2
- QZRLETONGKUVFA-UHFFFAOYSA-N [K].[Cs] Chemical compound [K].[Cs] QZRLETONGKUVFA-UHFFFAOYSA-N 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 230000035699 permeability Effects 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J43/00—Secondary-emission tubes; Electron-multiplier tubes
- H01J43/04—Electron multipliers
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J43/00—Secondary-emission tubes; Electron-multiplier tubes
- H01J43/04—Electron multipliers
- H01J43/06—Electrode arrangements
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J43/00—Secondary-emission tubes; Electron-multiplier tubes
- H01J43/04—Electron multipliers
- H01J43/06—Electrode arrangements
- H01J43/10—Dynodes
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Abstract
The first stage dynode is a first stage dynode used for a photomultiplier, and includes a bottom wall portion, a pair of side wall portions extending to one side from both end portions of the bottom wall portion in a predetermined direction, a first holding portion extending to the outside from the end portions of the bottom wall portion, and a pair of second holding portions extending to one side from both end portions of the pair of side wall portions in the predetermined direction.
Description
Technical Field
The present invention relates to a first-stage dynode and a photomultiplier.
background
as a first-stage dynode used for a photomultiplier, dynodes having various shapes have been proposed. For example, U.S. Pat. No. 4112325 describes a first-stage dynode having a cup-like shape with a flat bottom surface as a dynode for the purpose of improving the collection efficiency of photoelectrons. In the first-stage dynode described in U.S. Pat. No. 4112325, an electron emission surface is formed by a flat bottom surface having a cup shape. In addition, japanese patent application laid-open No. 8-12772 describes a dynode in which a receiving port, into which photoelectrons enter, has a funnel shape as a first-stage dynode for the purpose of obtaining a signal current independent of the incident position of a photocathode. In the first-stage dynode described in japanese patent publication No. 8-12772, the electron emission surface is formed by three flat surfaces and one curved surface connected so as to be curved in a concave shape, and a pair of side surfaces is provided on both sides of the electron emission surface so as to be orthogonal to the electron emission surface.
Disclosure of Invention
However, in the first-stage dynode described in U.S. Pat. No. 4112325, since the electron emission surface is formed by the flat bottom surface of the cup-shaped structure, it is difficult to adjust the transit time of the secondary electrons from the first-stage dynode to the second-stage dynode, and as a result, there is a difference in the transit time of the secondary electrons from the first-stage dynode to the second-stage dynode. In the first-stage dynode described in japanese patent publication No. 8-12772, since a pair of side surfaces are provided on both sides of the electron emission surface so as to be orthogonal to the electron emission surface, secondary electrons emitted from a central region of the electron emission surface transit linearly, and secondary electrons emitted from a region near the side surface of the electron emission surface travel while being repelled by the side surface having the same potential, resulting in a difference in transit time of secondary electrons from the first-stage dynode to the second-stage dynode. Therefore, in the first-stage dynode described in the specification of U.S. Pat. No. 4112325 and japanese patent publication No. 8-12772, it is expected that it is difficult to suppress the Difference in electron Transit Time (c.t.t.d.: CathodeTransit Time Difference) and the variation in electron Transit Time (t.t.s.: Transit Time Spread) in the photomultiplier tube.
Accordingly, an object of the present invention is to provide a first-stage dynode capable of suppressing an electron transit time difference and an electron transit time dispersion in a photomultiplier, and a photomultiplier including the first-stage dynode.
The first stage dynode of the present invention is a first stage dynode for a photomultiplier tube, and includes a bottom wall portion, a pair of side wall portions extending to one side from both end portions of the bottom wall portion in a predetermined direction, a first holding portion extending to the outside from the end portions of the bottom wall portion, and a pair of second holding portions extending to one side from both end portions of the pair of side wall portions in the predetermined direction.
In the first-stage dynode, each of a pair of side surfaces constituting the electron emission surface is a curved surface curved in a concave shape in a cross section parallel to a predetermined direction. Therefore, each side surface is located closer to one electron passage opening as it is farther from the center of the electron emission surface in the predetermined direction. As a result, the transit distance of the photoelectrons incident on each side surface and the transit distance of the secondary electrons emitted from each side surface become shorter as each side surface approaches one electron passage opening. The bottom surface constituting the electron emission surface is a curved surface curved in a concave shape in a cross section perpendicular to the predetermined direction. Therefore, the adjustment of the transit time of the secondary electrons from the first-stage dynode to the second-stage dynode becomes easy. In addition, since both photoelectrons incident on the electron emission surface and secondary electrons emitted from the electron emission surface pass through one (i.e., the same) electron passage opening, the dependence of the electron transit time on the incident position of the photoelectrons is reduced. Therefore, according to this first-stage dynode, the difference in electron transit time and the dispersion in electron transit time can be suppressed in the photomultiplier tube.
In the first-stage dynode of the present invention, the first holding portion may have a flat plate shape. With this configuration, the first-stage dynode can be easily and stably attached to the support member provided in the tube body of the photomultiplier tube by using the first holding portion.
in the first-stage dynode of the present invention, each of the pair of second holding portions may have a flat plate shape. With this configuration, the first-stage dynode can be easily and stably attached to the support member provided in the tube body of the photomultiplier tube using the pair of second holding portions.
In the first-stage dynode of the present invention, the bottom wall portion, the pair of side wall portions, the first holding portion, and the pair of second holding portions may be integrally formed of a metal plate. With this configuration, the first stage dynode can be easily manufactured and the structure can be simplified.
In the first stage dynode of the present invention, the respective radii of curvature of the pair of side faces may also be larger than 2 mm. With this configuration, the electron transit time difference and the electron transit time dispersion can be appropriately suppressed in the photomultiplier tube.
In the first-stage dynode of the present invention, R ≧ 0.1L may be satisfied where L represents the width of the electron emission surface in the predetermined direction and R represents the radius of curvature of each of the pair of side surfaces. With this configuration, the electron transit time difference and the electron transit time variation can be appropriately suppressed in the photomultiplier tube.
The photomultiplier of the present invention is provided with a photocathode, a multistage dynode including a first stage dynode and a second stage dynode arranged on a predetermined surface, the first stage dynode having a bottom wall portion, a pair of side wall portions extending from both end portions of the bottom wall portion in a predetermined direction perpendicular to the predetermined surface to the photocathode side and the second stage dynode side, a first holding portion extending from an end portion of the bottom wall portion on the photocathode side to an opposite side of the second stage dynode, a pair of second holding portions extending from both end portions of the pair of side wall portions in the predetermined direction to the photocathode side and the second stage dynode side, and an anode, the first stage dynode having an electron emission surface facing one electron passage opening formed by a bottom surface of the bottom wall portion on the photocathode side and a pair side surfaces of the pair of side wall portions on the photocathode side and the second stage dynode side, the bottom surface is a curved surface curved in a concave shape in a cross section perpendicular to the predetermined direction, and each of the pair of side surfaces is a curved surface curved in a concave shape in a cross section parallel to the predetermined direction.
According to this photomultiplier tube, the difference in electron transit time and the dispersion in electron transit time can be suppressed for the above-described reasons.
Drawings
Fig. 1 is a cross-sectional view of a photomultiplier tube according to an embodiment.
Fig. 2 is a cross-sectional view of the electron multiplier section and the anode shown in fig. 1.
FIG. 3 is a perspective view of an embodiment of a first stage dynode.
Fig. 4 is a cross-sectional view of the first stage dynode taken along the line IV-IV shown in fig. 3.
FIG. 5 is a cross-sectional view of the first stage dynode taken along the line V-V shown in FIG. 3.
Fig. 6 is a perspective view of the first-stage dynode of the comparative example.
Fig. 7 is a schematic diagram for explaining a transit trajectory of electrons.
Fig. 8 is a diagram showing an electron transit time difference and an electron transit time dispersion in a photomultiplier tube using the first stage dynode of the first embodiment.
fig. 9 is a diagram showing an electron transit time difference and an electron transit time dispersion in a photomultiplier tube using the first stage dynode of the second embodiment.
Fig. 10 is a diagram showing an electron transit time difference and an electron transit time dispersion in a photomultiplier tube using the first stage dynode of the third embodiment.
fig. 11 is a diagram showing an electron transit time difference and an electron transit time dispersion in a photomultiplier tube using the first stage dynode of the fourth embodiment.
Fig. 12 is a diagram showing the difference in electron transit time between a photomultiplier tube using the first-stage dynode of the first comparative example and a photomultiplier tube using the first-stage dynode of the fifth example.
Detailed Description
hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding portions are denoted by the same reference numerals, and redundant description thereof is omitted.
[ Structure of photomultiplier ]
As shown in fig. 1, the photomultiplier 1 includes a tube 2, a photocathode 3, an accelerating electrode 4, a focusing electrode 5, an electron multiplier section 6, and an anode 7. The electron multiplier section 6 has a plurality of stages (e.g., 10 stages) of dynodes 10. In the following description, the photomultiplier tube 1 is referred to as "front" on the light incident side and "rear" on the opposite side. The tube axis (central axis) of the tube 2 is referred to as the "Z axis", the axis orthogonal to the plane (plane including the Z axis) on which the multistage dynodes 10 are arranged is referred to as the "X axis", and the axis orthogonal to the Z axis and the X axis is referred to as the "Y axis".
The tube 2 accommodates a photocathode 3, an accelerating electrode 4, a focusing electrode 5, an electron multiplier 6, and an anode 7 in a vacuum-evacuated space. The pipe body 2 is a glass bulb having light permeability. The tubular body 2 has an oblate spheroid portion 2a having a central axis of the Z axis, and a cylindrical portion 2b having a central axis of the Z axis on the rear side of the oblate spheroid portion 2 a. The oblate spheroid portion 2a and the cylindrical portion 2b are integrally formed as one glass vacuum tube. For example, the outer diameter of the oblate spheroid portion 2a is about 200mm and the outer diameter of the cylindrical portion 2b is about 85mm when viewed from the front side.
The photocathode 3 is set on the inner surface of the tube 2. Specifically, the photocathode 3 is provided on the inner surface of the front half of the oblate spheroid portion 2 a. The photocathode 3 constitutes a transmission-type photoelectric surface, and is formed of, for example, a potassium-cesium antimonide-type (double-alkali) material or another known material. When light enters the photocathode 3 from the front side, photoelectrons are emitted from the photocathode 3 to the rear side by the photoelectric effect. For example, the outer diameter of the photocathode 3 (i.e., the effective diameter of the photomultiplier tube 1) when viewed from the front side is about 200 mm. The broken line shown in fig. 1 indicates the trajectory (representative trajectory) of photoelectrons emitted from the photocathode 3.
The accelerating electrode 4 is disposed on the rear side of the photocathode 3. A predetermined voltage is applied to the accelerating electrode 4. The accelerating electrode 4 is configured to accelerate the photoelectrons emitted from the photocathode 3 toward the electron multiplier section 6. The focusing electrode 5 is disposed on the rear side of the accelerating electrode 4. A predetermined voltage is applied to the focusing electrode 5. The focusing electrode 5 is configured to focus the photoelectrons emitted from the photocathode 3 toward the electron multiplier section 6.
The electron multiplier section 6 is disposed on the rear side of the focusing electrode 5. The multistage dynodes 10 are arranged on YZ planes (planes including Y and Z axes). Each dynode 10 is formed of, for example, stainless steel. A predetermined voltage is applied to each of the multistage dynodes 10. The multistage dynode 10 as the electron multiplier 6 is configured to multiply the photoelectrons emitted from the photocathode 3. The anode 7 is disposed on the YZ plane in a state facing the dynode 10 of the final stage. A predetermined voltage is applied to the anode 7. The anode 7 is configured to output secondary electrons emitted from the dynode 10 of the final stage as a signal current.
The accelerating electrode 4, the focusing electrode 5, and each dynode 10 and anode 7 of the electron multiplier section 6 are supported by a support member (not shown) in the tube 2. The support member is attached to a stem (stem) (not shown) that seals the rear end of the cylindrical portion 2 b. Further, the stem is provided with a voltage application wiring and a signal current output wiring as a pin, a cable, or the like.
[ Structure of Electron multiplying part ]
As shown in fig. 2, in the electron multiplier section 6, the multistage dynode 10 includes a first stage dynode 11, a second stage dynode 12, and a third stage dynode 13. In the following description, each dynode including the first stage dynode 11, the second stage dynode 12, and the third stage dynode 13 is referred to as a dynode 10. The electron emission surface (surface on which electrons enter and from which secondary electrons are emitted) of each dynode including the electron emission surface 11a of the first-stage dynode 11, the electron emission surface 12a of the second-stage dynode 12, and the electron emission surface 13a of the third-stage dynode 13 is referred to as an electron emission surface 10 a.
The first-stage dynode 11 is disposed such that an electron emission surface 11a faces the photocathode 3 (see fig. 1) and an electron emission surface 12a of the second-stage dynode 12. The second-stage dynode 12 is disposed so that the electron emission surface 12a faces the electron emission surface 11a of the first-stage dynode 11 and the electron emission surface 13a of the third-stage dynode 13. Similarly, the electron emission surfaces 10a of the dynodes 10 of the third and subsequent stages except for the dynode 10 of the final stage are disposed so as to face the electron emission surface 10a of the dynode 10 of the preceding stage and the electron emission surface 10a of the dynode 10 of the subsequent stage. The dynode 10 of the final stage is disposed such that the electron emission surface 10a thereof faces the electron emission surface 10a of the dynode 10 of the preceding stage and the anode 7.
The first-stage dynode 11 includes a bottom wall portion 111, a pair of side wall portions 112, a first holding portion 113, and a pair of second holding portions 114 (described in detail later). The electron emission surface 11a of the first-stage dynode 11 is constituted by a bottom surface of the bottom wall portion 111 on the photocathode 3 side and on the second-stage dynode 12 side, and a pair of side surfaces of the pair of side wall portions 112 on the photocathode 3 side and on the second-stage dynode 12 side.
The second-stage dynode 12 has a bottom wall portion 121 and a pair of holding portions 122. The electron emission surface 12a of the second-stage dynode 12 is formed by the bottom surface of the bottom wall 121 on the first-stage dynode 11 side and the third-stage dynode 13 side. The pair of holding portions 122 extend from both end portions of the bottom wall portion 121 in the X-axis direction (direction parallel to the X-axis) toward the first-stage dynode 11 and toward the third-stage dynode 13.
The third stage dynode 13 includes a bottom wall portion 131 and a pair of holding portions 132. The electron emission surface 13a of the third-stage dynode 13 is formed by the bottom surface of the bottom wall 131 on the second-stage dynode 12 side and on the fourth-stage dynode 10 side. The pair of holding portions 132 extend from both ends of the bottom wall portion 131 in the X-axis direction toward the second-stage dynode 12 and toward the fourth-stage dynode 10.
A pair of electron lens forming electrodes 14 are provided in regions among the first stage dynode 11, the second stage dynode 12, and the third stage dynode 13. Specifically, one electron lens forming electrode 14 is formed integrally with one holding portion 132 so as to extend to a region between one second holding portion 114 and one holding portion 122. The other electron lens forming electrode 14 is formed integrally with the other holding portion 132 so as to extend to a region between the other second holding portion 114 and the other holding portion 122. A predetermined voltage applied to the third dynode 13 is applied to the pair of electron lens forming electrodes 14. Thereby, the potential distribution in the X-axis direction is flattened in the region between the first-stage dynode 11 and the second-stage dynode 12.
[ Structure of first-stage dynode ]
As shown in fig. 3, 4, and 5, the first-stage dynode 11 includes a bottom wall portion 111, a pair of side wall portions 112, a first holding portion 113, and a pair of second holding portions 114. The pair of side walls 112 extend from both ends of the bottom wall 111 in the X-axis direction (a predetermined direction perpendicular to the predetermined surface) to one side (the photocathode 3 side and the second-stage dynode 12 side (see fig. 1 and 2)). The first holding portion 113 extends outward (opposite side to the second-stage dynode (see fig. 1 and 2)) from an end portion on the front side (the photocathode 3 side (see fig. 1 and 2)) of the bottom wall portion 111. The pair of second holding portions 114 extend from both end portions of the pair of side wall portions 112 in the X-axis direction to one side.
the first holding portion 113 has a flat plate shape (for example, a rectangular plate shape) parallel to the XY plane. Each of the pair of second holding portions 114 has a flat plate shape parallel to the YZ plane. The first-stage dynode 11 is attached to a support member provided in the tube 2 via the first holding portion 113 and the pair of second holding portions 114.
the electron emission surface 11a of the first-stage dynode 11 is constituted by a bottom surface 111a on one side of the bottom wall portion 111 and a pair of side surfaces 112a on one side of the pair of side wall portions 112. The electron emission surface 11a is opposed to one electron passage opening 11 b. In the first-stage dynode 11, one electron passage opening 11b is defined by one side edge portions of the bottom wall portion 111, the pair of side wall portions 112, and the pair of second holding portions 114. That is, the photoelectrons incident on the electron emission surface 11a and the secondary electrons emitted from the electron emission surface 11a all pass through one (i.e., the same) electron passage opening 11 b.
The bottom surface 111a constituting the electron emission surface 11a is a curved surface curved in a concave shape in a cross section perpendicular to the X-axis direction (see fig. 4 in particular). In the present embodiment, the bottom surface 111a is a cylindrical surface (an elliptic cylindrical surface, a hyperbolic cylindrical surface, a parabolic cylindrical surface, a composite surface thereof, or the like) in which the X-axis direction is set as the longitudinal direction (the height direction of the cylinder). Each of the pair of side surfaces 112a constituting the electron emission surface 11a is a curved surface curved in a concave shape in a cross section parallel to the X-axis direction (see fig. 5 in particular). In the present embodiment, each side surface 112a corresponds to a chamfered surface when a rounded inner chamfer is formed at a corner (corner) formed by the bottom surface 111a and the inner surface of each second holding portion 114. The bottom surface 111a and the side surfaces 112a are connected to each other so as to have a continuous curvature. The side surfaces 112a and the inner surfaces of the second holding portions 114 are also connected to each other so as to have a continuous curvature.
When the width of the electron emission surface 11a in the X-axis direction is L and the radius of curvature of each of the pair of side surfaces 112a is R (see fig. 5), R ≧ 0.1L is established in the first-stage dynode 11. In addition, the pair of side surfaces 112a have respective radii of curvature R larger than 2 mm. For example, the width L of the electron emission surface 11a in the X-axis direction is greater than 20mm and less than 50 mm.
the first stage dynode 11 having the above shape is integrally formed of a metal plate (e.g., a stainless steel plate having a thickness of about 0.3 mm). That is, the bottom wall portion 111, the pair of side wall portions 112, the first holding portion 113, and the pair of second holding portions 114 are integrally formed of a metal plate. Here, the metal plate is integrally formed, that is, the metal plate is formed by performing plastic working such as press working.
[ Effect and Effect ]
In the first-stage dynode 11, each of the pair of side surfaces 112a constituting the electron emission surface 11a is a curved surface curved in a concave shape in a cross section parallel to the X-axis direction. Therefore, the farther each side surface 112a is from the center of the electron emission surface 11a in the X-axis direction, the closer it is to one electron passage opening 11 b. As a result, the transit distance of the photoelectrons incident on each side surface 112a and the transit distance of the secondary electrons emitted from each side surface 112a are shortened as each side surface 112a approaches one electron passage opening 11 b. The bottom surface 111a constituting the electron emission surface 11a is a curved surface curved in a concave shape in a cross section perpendicular to the X-axis direction. Therefore, the adjustment of the transit time of the secondary electrons from the first-stage dynode 11 to the second-stage dynode 12 becomes easy. Further, since all the photoelectrons incident on the electron emission surface 11a and the secondary electrons emitted from the electron emission surface 11a pass through one (i.e., the same) electron passage opening 11b, the dependence of the electron transit time with respect to the incident position of the photoelectrons is reduced. Therefore, according to the first-stage dynode 11, the difference in electron transit time and the dispersion in electron transit time can be suppressed in the photomultiplier tube 1.
Further, even if the entire electron emission surface is formed into, for example, a spherical shape, in the first-stage dynode having such an electron emission surface, it is difficult to adjust the transit time of the secondary electrons from the first-stage dynode to the second-stage dynode, and the difference in electron transit time and the dispersion in electron transit time cannot be effectively suppressed in the photomultiplier tube. In order to suppress the difference in electron transit time and the dispersion in electron transit time, it is also conceivable to form the electron emission surface only with the bottom surface 111a without providing the pair of side surfaces 112a and to increase the width of the electron emission surface in the X-axis direction. However, in the first-stage dynode having such an electron emission surface, since the size thereof is increased, the outer diameter of the cylindrical portion 2b of the tube 2 is also inevitably increased, and it is difficult to ensure the water pressure resistance of the tube 2. Further, when the size of the first stage dynode is increased, it is also difficult to form the first stage dynode by subjecting a metal plate to plastic working such as press working. According to the first stage dynode 11, it is possible to suppress an increase in size thereof, and to suppress an electron transit time difference and an electron transit time variation in the photomultiplier tube 1.
In the first-stage dynode 11, the first holding portion 113 has a flat plate shape. With this configuration, the first-stage dynode 11 can be easily and stably attached to the support member provided in the tube body 2 of the photomultiplier tube 1 using the first holding portion 113.
in the first-stage dynode 11, each of the pair of second holding portions 114 has a flat plate shape. With this configuration, the first-stage dynode 11 can be easily and stably attached to the support member provided in the tube body 2 of the photomultiplier tube 1 using the pair of second holding portions 114.
in the first-stage dynode 11, the bottom wall portion 111, the pair of side wall portions 112, the first holding portion 113, and the pair of second holding portions 114 are integrally formed of a metal plate. With this configuration, the first-stage dynode 11 can be easily manufactured and simplified in structure.
in addition, in the first-stage dynode 11, the respective radii of curvature R of the pair of side surfaces 112a are larger than 2 mm. With this configuration, the electron transit time difference and the electron transit time dispersion can be appropriately suppressed in the photomultiplier tube 1.
in the first-stage dynode 11, R ≧ 0.1L is satisfied where L is the width of the electron emission surface 11a in the X-axis direction and R is the radius of curvature of each of the pair of side surfaces 112 a. With this configuration, the electron transit time difference and the electron transit time dispersion can be appropriately suppressed in the photomultiplier tube 1.
Here, the reason why the difference in the transit time of the secondary electrons to the second-stage dynode 12 is less likely to occur in the first-stage dynode 11 will be described in more detail.
Fig. 6 is a perspective view of the first-stage dynode 15 of the comparative example. As shown in fig. 6, the first-stage dynode 15 of the comparative example is different from the first-stage dynode 11 described above mainly in that the pair of side wall portions 112 are not provided, and the pair of second holding portions 114 intersect with the bottom wall portion 111. In the first-stage dynode 15 of the comparative example, the bottom surface 111a constitutes an electron emission surface 15a opposed to one electron passage opening 15 b.
In the first-stage dynode 15 of the comparative example, as shown in fig. 7(a), photoelectrons pass through the central region of the electron emission surface 15a at the trajectory a1, and secondary electrons emitted from the central region transit linearly at the trajectory B1. On the other hand, the photoelectrons enter the vicinity of the second holding portion 114 on the electron emission surface 15a at the trajectory a2, and secondary electrons emitted from the vicinity repel the second holding portion 114 having the same potential, and transit at the trajectory B2. As a result, in the first-stage dynode 15 of the comparative example, a difference in transit time of the secondary electrons to the second-stage dynode 12 is likely to occur.
On the other hand, in the first-stage dynode 11, as shown in fig. 7(B), photoelectrons pass through the central region of the electron emission surface 11a at the trajectory a1, and secondary electrons emitted from the central region transit linearly at the trajectory B1. On the other hand, the photoelectrons pass through the vicinity of the second holding portion 114 (i.e., the side surface 112a) where the photoelectrons enter the electron emission surface 11a at the trajectory a2, and the secondary electrons emitted from the vicinity repel the second holding portion 114 having the same potential and transit through the trajectory B2, but the transit distance of the photoelectrons entering the vicinity and the transit distance of the secondary electrons emitted from the vicinity are both reduced by the amount corresponding to the distance by which the side surface 112a approaches the electron passage opening 11B. As a result, in the first-stage dynode 11, it is difficult for a difference in transit time of the secondary electrons to the second-stage dynode 12 to occur.
Next, the reason why the curvature radius R of each of the pair of side surfaces 112a constituting the electron emission surface 11a in the first-stage dynode 11 is more preferably larger than 2mm will be described together with the simulation results.
First, as simulation models, a first-stage dynode of the first embodiment, a first-stage dynode of the second embodiment, a first-stage dynode of the third embodiment, and a first-stage dynode of the fourth embodiment were prepared. Each first-stage dynode was formed by press working on a stainless steel plate having a thickness of 0.3 mm. In each first-stage dynode, the width L of the electron emission surface in the X-axis direction was set to 30.6 mm.
The first-stage dynodes have the same configuration as the first-stage dynode 11 described above, and differ from each other only at the following points. That is, the radius of curvature R in the first-stage dynode of the first embodiment is set to 2mm, the radius of curvature R in the first-stage dynode of the second embodiment is set to 4mm, the radius of curvature R in the first-stage dynode of the third embodiment is set to 6mm, and the radius of curvature R in the first-stage dynode of the fourth embodiment is set to 8 mm.
In simulations corresponding to the case where the first-stage dynode of the first embodiment, the first-stage dynode of the second embodiment, the first-stage dynode of the third embodiment, and the first-stage dynode of the fourth embodiment were mounted in the same photomultiplier tube, respectively, and the photomultiplier tube was operated under the same conditions, the electron transit time difference and the electron transit time variation in the X-axis direction were measured.
Fig. 8(a) is a diagram showing an electron transit time difference of a photomultiplier tube using the first stage dynode of the first embodiment, and fig. 8(b) is a diagram showing an electron transit time dispersion in this case. Fig. 9(a) is a diagram showing an electron transit time difference of a photomultiplier tube using the first stage dynode of the second embodiment, and fig. 9(b) is a diagram showing an electron transit time variation in this case. Fig. 10(a) is a diagram showing an electron transit time difference of a photomultiplier tube using the first stage dynode of the third embodiment, and fig. 10(b) is a diagram showing an electron transit time dispersion in this case. Fig. 11(a) is a diagram showing an electron transit time difference of a photomultiplier tube using the first stage dynode of the fourth embodiment, and fig. 11(b) is a diagram showing an electron transit time variation in this case.
As shown in fig. 8(a), 9(a), 10(a) and 11(a), in the photomultiplier tube using the first-stage dynode of the second embodiment, the first-stage dynode of the third embodiment and the first-stage dynode of the fourth embodiment, the electron transit time difference in the X-axis direction is further uniformized at both end portions in the X-axis direction than in the photomultiplier tube using the first-stage dynode of the first embodiment. As shown in fig. 8(b), 9(b), 10(b) and 11(b), in the photomultiplier tube using the first-stage dynode of the second embodiment, the first-stage dynode of the third embodiment and the first-stage dynode of the fourth embodiment, the electron transit time variation in the X-axis direction is further reduced as compared with the photomultiplier tube using the first-stage dynode of the first embodiment.
from the above simulation results, it can be said that, in the photomultiplier tube, in order to suppress the difference in electron transit time and the dispersion in electron transit time, it is more preferable that the respective radii of curvature R of the pair of side surfaces constituting the electron emission surface be larger than 2 mm.
Next, the reason why R ≧ 0.1L is more preferable in the first-stage dynode 11 will be described together with the simulation result.
According to the simulation results described above, R ≧ 0.1L is satisfied for the first-stage dynode (L: 30.6mm, R: 2mm) of the first embodiment, and R ≧ 0.1L is satisfied for the first-stage dynode (L: 30.6mm, R: 4mm) of the second embodiment, the first-stage dynode (L: 30.6mm, R: 6mm) of the third embodiment, and the first-stage dynode (L: 30.6mm, R: 8mm) of the fourth embodiment. Therefore, even when the width L of the electron emission surface in the X-axis direction is not 30.6mm, it can be said that R ≧ 0.1L is preferably established in the first-stage dynode in order to suppress the difference in electron transit time and the dispersion in electron transit time in the photomultiplier tube, and this is confirmed by simulation.
First, as simulation models, the first stage dynode of the first comparative example and the first stage dynode of the fifth embodiment were prepared. Each first-stage dynode was formed by press working a stainless steel plate having a thickness of 0.3 mm. In the first stage dynode of the first comparative example, the width L of the electron emission surface in the X-axis direction was 34mm, and the curvature radius R of each of the pair of side surfaces was 0mm (that is, the first stage dynode of the first comparative example had the same configuration as the first stage dynode 15 shown in fig. 6). In the first-stage dynode of the fifth embodiment, the width L of the electron emission surface in the X-axis direction is 34mm, and the respective radii of curvature R of the pair of side surfaces are 5mm (that is, the first-stage dynode of the fifth embodiment has the same configuration as the first-stage dynode 11 described above).
In a simulation corresponding to a case where the first stage dynode of the first comparative example and the first stage dynode of the fifth example were mounted on the same photomultiplier tube, and the photomultiplier tube was operated under the same conditions, the difference in electron transit time in the X-axis direction was measured. Fig. 12(a) is a diagram showing an electron transit time difference of a photomultiplier tube using the first stage dynode of the first comparative example, and fig. 12(b) is a diagram showing an electron transit time difference of a photomultiplier tube using the first stage dynode of the fifth example.
As shown in fig. 12(a) and (b), in the photomultiplier tube using the first-stage dynode of the fifth example, the electron transit time difference in the X-axis direction is made uniform at both ends in the X-axis direction as compared with the photomultiplier tube using the first-stage dynode of the first comparative example. From the simulation results, it can be said that R ≧ 0.1L is more preferably satisfied in the first-stage dynode in terms of suppressing the electron transit time difference and the electron transit time dispersion in the photomultiplier tube.
[ modified examples ]
The present invention is not limited to the above-described embodiments. For example, the material and shape of each structure are not limited to those described above, and various materials and shapes can be used. For example, the first holding portion 113 is not limited to a rectangular plate shape, and may have another shape such as a semicircular plate shape.
Further, one edge of each of the pair of second holding portions 114 may be formed to protrude from one edge of the bottom wall portion 111 and the pair of side wall portions 112, or may be formed to be recessed from one edge of the bottom wall portion 111 and the pair of side wall portions 112.
The bottom wall 111, the pair of side walls 112, the first holding portion 113, and the pair of second holding portions 114 may not be formed in a plate shape. For example, the bottom wall 111, the pair of side walls 112, the first holding portion 113, and the pair of second holding portions 114 may be formed in a block shape, and the electron emission surface 11a may be formed by cutting or the like.
According to the present invention, it is possible to provide a first-stage dynode capable of suppressing an electron transit time difference and an electron transit time dispersion in a photomultiplier tube, and a photomultiplier tube including the first-stage dynode.
Claims (7)
1. A first stage dynode for a photomultiplier tube, wherein,
The disclosed device is provided with:
A bottom wall portion;
A pair of side wall portions extending from both end portions of the bottom wall portion in a predetermined direction to one side;
a first holding portion extending outward from an end portion of the bottom wall portion; and
A pair of second holding portions extending from both end portions of the pair of side wall portions in the predetermined direction to the one side,
an electron emission surface facing one electron passage opening is formed by a bottom surface of the bottom wall portion on the one side and a pair of side surfaces of the pair of side wall portions on the one side,
The bottom surface is a curved surface curved in a concave shape on a cross section perpendicular to the predetermined direction,
Each of the pair of side surfaces is a curved surface curved in a concave shape in a cross section parallel to the predetermined direction.
2. The first stage dynode of claim 1, wherein,
the first holding portion is flat.
3. The first stage dynode of claim 1 or 2, wherein,
each of the pair of second holding portions has a flat plate shape.
4. The first stage dynode of any one of claims 1 to 3,
The bottom wall portion, the pair of side wall portions, the first holding portion, and the pair of second holding portions are integrally formed of a metal plate.
5. the first stage dynode of any one of claims 1 to 4,
The pair of sides each have a radius of curvature greater than 2 mm.
6. the first stage dynode of any one of claims 1 to 5, wherein,
When the width of the electron emission surface in the predetermined direction is L and the radius of curvature of each of the pair of side surfaces is R, R ≧ 0.1L is satisfied.
7. A photomultiplier tube, wherein,
The disclosed device is provided with:
A photocathode;
A multi-stage dynode; and
an anode, a cathode, a anode and a cathode,
the multistage dynode includes a first stage dynode and a second stage dynode arranged on a prescribed plane,
The first stage dynode has:
A bottom wall portion;
A pair of side wall portions extending from both end portions of the bottom wall portion in a predetermined direction perpendicular to the predetermined surface toward the photocathode side and toward the second-stage multiplier side;
A first holding portion extending from an end portion of the bottom wall portion on the photocathode side toward an opposite side of the second-stage dynode; and
A pair of second holding portions extending from both end portions of the pair of side wall portions in the predetermined direction toward the photocathode side and toward the second-stage multiplier side,
In the first-stage dynode, an electron emission surface facing one electron passage opening is formed by the bottom surface of the bottom wall portion on the photocathode side and the second-stage dynode side and a pair of side surfaces of the pair of side wall portions on the photocathode side and the second-stage dynode side,
The bottom surface is a curved surface curved in a concave shape on a cross section perpendicular to the predetermined direction,
each of the pair of side surfaces is a curved surface curved in a concave shape in a cross section parallel to the predetermined direction.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2018108696A JP7033501B2 (en) | 2018-06-06 | 2018-06-06 | 1st stage dynode and photomultiplier tube |
| JP2018-108696 | 2018-06-06 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN110571124A true CN110571124A (en) | 2019-12-13 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201910486094.0A Pending CN110571124A (en) | 2018-06-06 | 2019-06-05 | First-stage dynode and photomultiplier |
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| Country | Link |
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| JP (1) | JP7033501B2 (en) |
| CN (1) | CN110571124A (en) |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2092937A6 (en) * | 1970-04-03 | 1972-01-28 | Hyperelec | |
| JPH09180670A (en) * | 1995-12-26 | 1997-07-11 | Hamamatsu Photonics Kk | Photomultiplier tube |
| CN1444770A (en) * | 2000-07-27 | 2003-09-24 | 滨松光子学株式会社 | Photomultiplier |
| CN1902729A (en) * | 2004-01-08 | 2007-01-24 | 滨松光子学株式会社 | Photomultiplier tube |
| CN101111923A (en) * | 2005-01-25 | 2008-01-23 | 浜松光子学株式会社 | Electron multiplier unit and photomultiplier including the same |
| CN104603909A (en) * | 2012-09-05 | 2015-05-06 | 浜松光子学株式会社 | Electron tube |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1571551A (en) * | 1976-02-04 | 1980-07-16 | Rca Corp | Electron discharge tube having an electron emissive electrode |
| US7821203B2 (en) | 2006-10-16 | 2010-10-26 | Hamamatsu Photonics K.K. | Photomultiplier |
-
2018
- 2018-06-06 JP JP2018108696A patent/JP7033501B2/en active Active
-
2019
- 2019-06-05 CN CN201910486094.0A patent/CN110571124A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2092937A6 (en) * | 1970-04-03 | 1972-01-28 | Hyperelec | |
| JPH09180670A (en) * | 1995-12-26 | 1997-07-11 | Hamamatsu Photonics Kk | Photomultiplier tube |
| CN1444770A (en) * | 2000-07-27 | 2003-09-24 | 滨松光子学株式会社 | Photomultiplier |
| CN1902729A (en) * | 2004-01-08 | 2007-01-24 | 滨松光子学株式会社 | Photomultiplier tube |
| CN101111923A (en) * | 2005-01-25 | 2008-01-23 | 浜松光子学株式会社 | Electron multiplier unit and photomultiplier including the same |
| CN104603909A (en) * | 2012-09-05 | 2015-05-06 | 浜松光子学株式会社 | Electron tube |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2019212516A (en) | 2019-12-12 |
| JP7033501B2 (en) | 2022-03-10 |
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