photomultiplier tube

Abstract

A photomultiplier tube includes a photoelectric surface, an Nth-order (N is an integer greater than or equal to 2) dynode that multiplies electrons emitted from the photoelectric surface, and an anode that collects electrons multiplied by the dynode. The anode has an electron collecting surface that is opposite to the secondary electron emission surface of the Nth-order dynode and extends at least partly along the secondary electron emission surface, and there are no electron passage holes in the electron path from the (N-1)th-order dynode to the Nth-order dynode.

Description

Technical Field

[0001] This disclosure relates to a photomultiplier tube. Background Technology

[0002] A photomultiplier tube is known, comprising a photoelectric surface, an N-stage (N is an integer greater than or equal to 2) dynode that multiplies electrons emitted from the photoelectric surface, and an anode that collects electrons multiplied by the dynode (see, for example, Patent Document 1). In such a photomultiplier tube, the anode includes a mesh structure having multiple electron passage holes along the electron path from the (N-1)th dynode to the Nth dynode.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 7-245078 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] In the photomultiplier tube described above, electrons are unlikely to collide with the anode, and there is a possibility that electrons stray before colliding with the anode. In this case, time characteristics such as the fall time of the signal waveform output from the anode (the time it takes for the output pulse wave high value to return from 90% to 10% of the peak value) may deteriorate.

[0008] This disclosure was made in view of the above-mentioned circumstances, and its purpose is to provide a photomultiplier tube that can improve the time characteristics caused by the anode.

[0009] means for solving problems

[0010] The photomultiplier tube disclosed herein is [1] "a photomultiplier tube comprising: a photoelectric surface; an N-th order (N is an integer greater than 2) multiplier electrode that multiplies electrons emitted from the photoelectric surface; and an anode that collects electrons multiplied by the multiplier electrode, the anode having an electron collecting surface that is opposite to the secondary electron emission surface of the N-th order multiplier electrode and at least a portion of which extends along the secondary electron emission surface, and having no electron passage hole in the electron path from the (N-1)-th order multiplier electrode to the N-th order multiplier electrode."

[0011] In this photomultiplier tube, at least a portion of the anode, opposite the secondary electron emission surface of the Nth-stage dynode, extends along that surface. This anode does not have an electron passage hole in the electron path from the (N-1)th-stage dynode to the Nth-stage dynode. Therefore, electron deflection caused by the electron passage hole of the anode can be prevented, and electrons can easily enter the anode from the Nth-stage dynode. As a result, the timing characteristics originating from the anode can be improved.

[0012] The photomultiplier tube disclosed herein can also be [2] "the photomultiplier tube according to [1], wherein the anode is disposed between the dynode of the (N-1)th stage and the dynode of the Nth stage." In this case, it is easy to configure the anode close to the dynode of the Nth stage, which can be configured in a way that increases the electric field strength between the anode and the dynode of the Nth stage.

[0013] The photomultiplier tube disclosed herein may also be [3] "a photomultiplier tube according to [1] or [2], wherein it has a wall portion disposed between the (N-1)th stage dynode and the anode, preventing electrons from entering the anode from the (N-1)th stage dynode." In this case, it is possible to prevent electrons from entering the anode by skipping the Nth stage dynode from the (N-1)th stage dynode.

[0014] The photomultiplier tube disclosed herein can also be [4] "the photomultiplier tube according to [3], wherein the wall portion is applied with a potential greater than or equal to the potential of the dynode of the (N-1)th stage". In this case, the wall portion can effectively prevent electrons from entering the anode from the dynode of the (N-1)th stage.

[0015] The photomultiplier tube disclosed herein may also be [5] "the photomultiplier tube according to [3] or [4], wherein the wall portion is integrally formed with the multiplier electrode of the Nth stage." In this case, the wall portion can be easily provided using the multiplier electrode of the Nth stage.

[0016] The photomultiplier tube disclosed herein may also be [6] "a photomultiplier tube according to any one of [3] to [5], wherein the wall portion is disposed between the dynode of the (N-1)th stage and the dynode of the Nth stage, and electrons emitted from the dynode of the (N-1)th stage are incident on the dynode of the Nth stage through the space between the wall portion and the dynode of the Nth stage." In this case, electrons can be incident from the dynode of the (N-1)th stage to the dynode of the Nth stage by utilizing the space between the wall portion and the dynode of the Nth stage.

[0017] The photomultiplier tube disclosed herein may also be [7] "a photomultiplier tube according to any one of [1] to [6], wherein it has an extraction electrode disposed between the anode and the dynode of the Nth stage, which promotes the extraction of electrons from the dynode of the Nth stage." In this case, it is possible to promote the extraction of electrons from the dynode of the Nth stage, thereby improving the output linearity (dynamic range).

[0018] The photomultiplier tube disclosed herein can also be [8] "the photomultiplier tube according to [7], wherein the lead-out electrode is applied with a potential higher than that of the multiplier electrode of the Nth stage." In this case, the lead-out electrode can efficiently extract electrons.

[0019] The photomultiplier tube disclosed herein may also be [9] "the photomultiplier tube according to [7] or [8], wherein the extraction electrode is a mesh electrode." In this case, the mesh electrode can be used to facilitate the extraction of electrons from the Nth stage dynode.

[0020] Invention Effects

[0021] According to this disclosure, a photomultiplier tube that can improve the time characteristics originating from the anode can be provided. Attached Figure Description

[0022] Figure 1 This is a cross-sectional view of a photomultiplier tube according to one embodiment.

[0023] Figure 2 It means Figure 1 A cross-sectional view of the electron multiplier and the anode.

[0024] Figure 3 It indicates magnification. Figure 2 A partial 3D image.

[0025] Figure 4 It means Figure 1 A three-dimensional view of the electron multiplier and the anode.

[0026] Figure 5 This indicates the view when viewed from the Y direction. Figure 1 The diagram shows the electron multiplier and the anode.

[0027] Figure 6 It means Figure 1 A three-dimensional view of a portion of the electron multiplier.

[0028] Figure 7 This indicates the view when viewed from the Y direction. Figure 1 A diagram of a portion of the electron multiplication region.

[0029] Figure 8(a) represents the simulation results of the electron orbits from the eighth dynode to the ninth dynode in the electron multiplication section involved in the comparative example. Figure 8 (b) represents the simulation results of the electron orbits from the ninth dynode to the tenth dynode in the electron multiplication section involved in the comparative example. Figure 8 (c) represents the simulation results of the electron orbit from the tenth-order dynode to the anode in the electron multiplication section involved in the comparative example.

[0030] Figure 9 (a) represents the simulation results of the electron orbits from the eighth dynode to the ninth dynode in the electron multiplication section involved in the embodiment. Figure 9 (b) represents the simulation results of the electron orbits from the ninth dynode to the tenth dynode in the electron multiplication section involved in the embodiment. Figure 9 (c) represents the simulation results of the electron trajectory from the tenth-stage dynode to the anode in the electron multiplication section involved in the embodiment.

[0031] Figure 10 (a) is a graph showing the simulation results of the rise time for the comparative example and the embodiment. Figure 10 (b) is a graph showing the simulation results of the fall time for the comparative example and the embodiment.

[0032] Figure 11 (a) is a graph representing the measured values ​​of the output signal from the anode in the comparative example. Figure 11 (b) is a graph representing the measured values ​​of the output signal from the anode in the embodiment.

[0033] Figure 12 (a) is a three-dimensional view showing a portion of the electron multiplication part involved in the first modified example. Figure 12 (b) is a three-dimensional view showing a portion of the electron multiplication section involved in the second variation.

[0034] Figure 13 This is a perspective view showing a portion of the electron multiplication part involved in the third variation.

[0035] Figure 14 This is a diagram showing a portion of the electron multiplication region involved in the third variation when viewed from the Y direction.

[0036] Figure 15 This is a perspective view showing a portion of the electron multiplication part involved in the fourth variation.

[0037] Figure 16 This is a diagram showing a portion of the electron multiplication region involved in the fourth variation when viewed from the Y direction.

[0038] Figure 17 This is a diagram showing a portion of the electron multiplication region involved in the fourth variation when viewed from the X direction.

[0039] Figure 18 This is a cross-sectional view showing the electron multiplication part involved in the fifth variation. Detailed Implementation

[0040] Hereinafter, the embodiments will be described in detail with reference to the accompanying drawings. In the drawings, the same or equivalent parts are given the same reference numerals, and repeated descriptions are omitted.

[0041] like Figure 1 As shown, the photomultiplier tube 1 includes a tube body 2, a photoelectric surface 3, a focusing electrode 5, an electron multiplier section 6, an anode 7, and a partition (wall) 20. The electron multiplier section 6 has so-called line-focusing type N-stage (N is an integer of 2 or more) dynodes 10. In the following description, the side in which light is incident relative to the photomultiplier tube 1 is designated as "front", and the opposite side is designated as "rear". In addition, the tube axis (central axis) of the tube body 2 is designated as the "Z-axis", the axis orthogonal to the surface (including the Z-axis) on which multiple stages of dynodes 10 are arranged is designated as the "X-axis", and the axis orthogonal to both the Z-axis and the X-axis is designated as the "Y-axis".

[0042] The tube body 2 houses the photoelectric surface 3, the focusing electrode 5, the electron multiplier 6, and the anode 7 within a vacuum-sealed space. The tube body 2 is a transparent glass bulb. The tube body 2 has a flattened spherical portion 2a centered on the Z-axis and a cylindrical portion 2b centered on the Z-axis on the rear side of the flattened spherical portion 2a. The flattened spherical portion 2a and the cylindrical portion 2b are integrally formed as a single glass bulb.

[0043] The photoelectric surface 3 is disposed on the inner surface of the tube body 2. Specifically, the photoelectric surface 3 is disposed on the inner surface of the front half of the region of the oblate spheroidal portion 2a. The photoelectric surface 3 constitutes a transmission-type photocathode, and is formed, for example, from a potassium antimonide-cesium type (dual alkali) material or other known materials. When light is incident on the photoelectric surface 3 from the front, electrons (photoelectrons) are emitted from the photoelectric surface 3 to the rear through the photoelectric effect.

[0044] The focusing electrode 5 is disposed further rearward of the photoelectric surface 3. A predetermined voltage is applied to the focusing electrode 5. The focusing electrode 5 is configured to focus electrons emitted from the photoelectric surface 3 toward the electron multiplier 6.

[0045] The electron multiplier 6 is disposed further rearward from the photoelectric surface 3. The electron multiplier 6, i.e., the N-stage dynode 10, multiplies the electrons emitted from the photoelectric surface 3 (secondary electron multiplication). The dynode 10 is formed, for example, of stainless steel. The dynode 10 is a long strip-shaped component with the X-direction as its length direction. The dynode 10 includes a bottom wall 13B with an arc-shaped cross-section along the YZ plane (a plane including the Y-axis and Z-axis). Figure 6 ) and the side walls 13W located at both ends of the bottom wall 13B in the X direction (refer to Figure 6 It is constructed as follows. In the side wall 13W of the dynode 10, a retaining piece (not shown) protruding outward in the X direction is provided as a component for holding the dynode 10 in the tube body 2.

[0046] Each of the N-stage dynodes 10 has a secondary electron emitting surface 11 that multiplies electrons. The secondary electron emitting surface 11 emits secondary electrons upon electron incidence. The secondary electron emitting surface 11 is located on the inner surface of the bottom wall 13B of the dynode 10, and its cross-section along the YZ plane is arc-shaped. That is, the cross-section of the dynode 10 intersecting its length direction is arc-shaped. Different potentials are applied to each dynode 10.

[0047] Anode 7 is configured opposite to the Nth stage dynode 10, which is the final stage. A predetermined voltage is applied to anode 7. Anode 7 collects electrons multiplied by the Nth stage dynode 10. Anode 7 is configured to output a signal current by means of electrons emitted from the Nth stage dynode 10. In other words, the electrode that has the function of collecting electrons that can be used as a signal current is anode 7.

[0048] The focusing electrode 5, the dynodes 10 of the electron multiplier section 6, and the anode 7 are supported within the tube body 2 by support members (not shown) such as an insulating support substrate. This support member is mounted on a tube seat (not shown) at the rear end of the sealed cylindrical portion 2b. Furthermore, within this tube seat, wiring for voltage application and wiring for signal current output are provided as tube seat pins or cables, etc.

[0049] like Figure 1 and Figure 2 As shown, the electron multiplier 6 of this embodiment has 10 stages of dynodes 10 (i.e., N = 10). The 10 stages of dynodes 10 extend from the front side, which is the upstream side, toward the rear side, which is the downstream side, and include a first stage dynode 10a, a second stage dynode 10b, a third stage dynode 10c, a fourth stage dynode 10d, a fifth stage dynode 10e, a sixth stage dynode 10f, a seventh stage dynode 10g, an eighth stage dynode 10h, a ninth stage dynode 10i, and a tenth stage dynode 10j.

[0050] The i-th stage dynode 10 (where i is an integer greater than 2 and less than N) is arranged opposite to the (i-1)-th stage dynode 10. In other words, the N-stage dynodes 10 are arranged such that the secondary electron emission surfaces 11 of adjacent dynodes 10 are opposite to each other. A higher potential is applied to the i-th stage dynode 10 than to the (i-1)-th stage dynode 10. A negative potential, for example the same voltage as the focusing electrode 5, is applied to the first stage dynode 10a. The N-stage dynodes 10 are arranged so that their central positions are aligned in the X direction.

[0051] like Figure 2 and Figure 3 As shown, the anode 7 is constructed by including a bottom wall 71 with an arcuate cross-section along the YZ plane and side walls 72 at both ends of the bottom wall 71 in the X direction. The outer surface of the bottom wall 71 has an electron collecting surface 73. The electron collecting surface 73 is opposite to the secondary electron emission surface 11j of the tenth-stage dynode 10j, and at least a portion of it extends along the secondary electron emission surface 11j. Here, the electron collecting surface 73 extends in imitation of the secondary electron emission surface 11j. In the illustrated example, the electron collecting surface 73 is arcuate along the YZ cross-section.

[0052] The anode 7 is disposed between the ninth-stage dynode 10i and the tenth-stage dynode 10j. The anode 7 is disposed such that a portion of it enters the tenth-stage dynode 10j. Thus, the electron collecting surface 73 is close to the secondary electron emitting surface 11j. The anode 7 does not have electron passage holes along the electron path from the ninth-stage dynode 10i to the tenth-stage dynode 10j. The anode 7 is a solid, plate-shaped metal component. The electron passage holes are formed by holes that allow electrons to pass through, for example, including mesh structures, honeycomb structures, and porous structures. That is, the anode 7 does not have at least one of mesh structures, honeycomb structures, and porous structures along the electron path from the ninth-stage dynode 10i to the tenth-stage dynode 10j. A potential greater than or equal to the potential of the tenth-stage dynode 10 is applied to the anode 7. The potential of the anode 7 is, for example, 0V.

[0053] A separator 20 is disposed between the ninth-stage dynode 10i and the anode 7. Separator 20 prevents electrons from entering the anode 7 from the ninth-stage dynode 10i and from entering the anode 7 from the eighth-stage dynode 10h. Separator 20 is also disposed between the ninth-stage dynode 10i and the tenth-stage dynode 10j. Separator 20 is a flat plate extending in the X direction. The width of separator 20 in the X direction is greater than the width of the dynode 10 in the X direction and greater than the width of the anode 7 in the X direction (see reference). Figure 5 The partition 20 is made of, for example, stainless steel.

[0054] A potential higher than that of the ninth-stage dynode 10i is applied to the separator 20. For example, a potential identical to that of the tenth-stage dynode 10j is applied to the separator 20. The separator 20 and the tenth-stage dynode 10j are separate components. For example, as... Figure 3 As shown, electrons emitted from the ninth-stage dynode 10i pass through the space K between the tenth-stage dynode 10j side of the partition 20 and the tenth-stage dynode 10j, and are incident on the tenth-stage dynode 10j (refer to the dashed arrow in the figure).

[0055] like Figure 2 , Figure 4 , Figure 5 , Figure 6 as well as Figure 7 As shown, the sidewall 13W of the dynode 10 extends along the YZ plane, and the width of the dynode 10 in the X direction (hereinafter, the width in the X direction is also simply referred to as "width") is constant. The width of the end edge E of the (m-1)th stage dynode 10 in the m-th stage (m is an integer of 2 or more and N less) is smaller than the width of the (m-1)th stage dynode 10. In other words, it becomes a structure in which the width of the end edge E of the (m-1)th stage dynode 10 in the m-th stage is different from the width of the (m-1)th stage dynode 10 (hereinafter also referred to as "nested structure"). In this embodiment, the m-th stage dynode 10 refers to a plurality of odd-numbered stages (other than the first stage) of dynode 10 that are different from each other.

[0056] Specifically, the width of the third-stage dynode 10c is smaller than the width of the second-stage dynode 10b. The width of the fifth-stage dynode 10e is smaller than the width of the fourth-stage dynode 10d. The width of the seventh-stage dynode 10g is smaller than the width of the sixth-stage dynode 10f. The width of the ninth-stage dynode 10i is smaller than the width of the eighth-stage dynode 10h. The widths of the third, fifth, seventh, and ninth-stage dynodes 10c, 10e, 10g, and 10i, which are multiple odd-numbered stages, are equal to each other. The widths of the second, fourth, sixth, eighth, and tenth-stage dynodes 10b, 10d, 10f, 10h, and 10j, which are multiple even-numbered stages, are equal to each other.

[0057] In the X direction, the edge E of the m-th stage dynode 10 is contained inside the (m-1)-th stage dynode 10. That is, in the X direction, one sidewall 13W of the m-th stage dynode 10 is located more inner than one sidewall 13W of the (m-1)-th stage dynode 10, and the other sidewall 13W of the m-th stage dynode 10 is located more inner than the other sidewall 13W of the (m-1)-th stage dynode 10. In this embodiment, in the X direction, the third stage dynode 10c is contained inside the second stage dynode 10b, the fifth stage dynode 10e is contained inside the fourth stage dynode 10d, the seventh stage dynode 10g is contained inside the sixth stage dynode 10f, and the ninth stage dynode 10i is contained inside the eighth stage dynode 10h.

[0058] In the X direction, the width of the first-stage dynode 10a is greater than the width of the second to tenth-stage dynodes 10b to 10j. In the X direction, the second to tenth-stage dynodes 10b to 10j are contained within the first-stage dynode 10a. In other words, in the X direction, one end of the second to tenth-stage dynodes 10b to 10j is located further inside than one end of the first-stage dynode 10a, and the other end of the second to tenth-stage dynodes 10b to 10j is located further inside than the other end of the first-stage dynode 10a.

[0059] Viewed from the X direction, the edge E of the m-th stage dynode 10 enters the (m-1)-th stage dynode 10. Specifically, viewed from the X direction, the edge E of multiple odd-numbered stages (excluding the first and third stages) of dynode 10, which are different from each other, enters the dynode 10 adjacent to the upstream side of that dynode 10. More specifically, the edge E of the fifth stage dynode 10e is a nested structure with a width different from that of the fourth stage dynode 10d, in which the edge E of the fifth stage dynode 10e enters the internal space of the fourth stage dynode 10d (the space divided by the sidewall 13W and the bottom wall 13B). The edge E of the seventh stage dynode 10g is a nested structure with a width different from that of the sixth stage dynode 10f, in which the edge E of the seventh stage dynode 10g enters the internal space of the sixth stage dynode 10f. The edge E of the ninth-stage dynode 10i is a nested structure with a width different from that of the eighth-stage dynode 10h. In this nested structure, the edge E of the ninth-stage dynode 10i enters the internal space of the eighth-stage dynode 10h. In other words, the fourth-stage dynode 10d side of the fifth-stage dynode 10e enters the internal space of the fourth-stage dynode 10d, the sixth-stage dynode 10f side of the seventh-stage dynode 10g enters the internal space of the sixth-stage dynode 10f, and the eighth-stage dynode 10h side of the ninth-stage dynode 10i enters the internal space of the eighth-stage dynode 10h.

[0060] Furthermore, viewed from the X direction, the edge E of the second-stage dynode 10b enters the first-stage dynode 10a. Specifically, the edge E of the second-stage dynode 10b is a nested structure with a width different from that of the first-stage dynode 10a, in which the edge E of the second-stage dynode 10b enters the internal space of the first-stage dynode 10a. Additionally, the third-stage dynode 10c does not enter the second-stage dynode 10b and is configured separately from it. The fourth-stage dynode 10d does not enter the third-stage dynode 10c and is configured separately from it. The sixth-stage dynode 10f does not enter the fifth-stage dynode 10e and is configured separately from it. The eighth-stage dynode 10h does not enter the seventh-stage dynode 10g and is configured separately from it. The tenth stage dynode 10j does not enter the ninth stage dynode 10i, and is configured separately from the ninth stage dynode 10b.

[0061] In the photomultiplier tube 1 configured as described above, when measurement light is incident on the photoelectric surface 3, electrons are emitted from the photoelectric surface 3. These electrons are focused by the focusing electrode 5 and sent to the electron multiplier section 6. In the electron multiplier section 6, electrons are sequentially incident on and emitted to the secondary electron emission surfaces 11a-11j of the first to tenth stage multipliers 10a-10j, where they are multiplied. Then, the multiplied electrons are collected at the electron collection surface 73 of the anode 7 and extracted from the anode 7 as an output signal.

[0062] Figure 8 of (a) Figure 8 (b) and Figure 8 (c) represents a simulation result of a portion of the electron orbitals in the electron multiplier 906 involved in the comparative example. Figure 9 of (a) Figure 9 (b) and Figure 9 (c) shows a simulation result representing a portion of the electron orbitals in the electron multiplication unit 6 according to the embodiment. In each figure, multiple thin lines represent electron orbitals. Figure 8 As shown in (a), the electron multiplier 906 involved in the comparative example differs from the electron multiplier 6 in that, instead of multiple multiplier electrodes 10 (see Figure 6), Figure 3 It has multiple multiplier electrodes 910, replacing anode 7 (refer to...). Figure 3 It has an anode 907 but no partition 20 (see reference). Figure 3 ).

[0063] The widths of the multiple dynodes 910 are equal. The m-th dynode 910 does not enter the (m-1)-th dynode 10 and is configured separately from the (m-1)-th dynode 10. The tenth-stage dynode 910j has a U-shaped cross-section with an opening to the front along the YZ plane. The secondary electron emission surface 911 of the tenth-stage dynode 910j is provided on the outer surface of the rear side of the dynode 910 and is linear along the cross-section of the YZ plane. The anode 907 has a mesh structure 930 containing multiple electron passage holes H0 for electrons to pass through along the electron path from the ninth-stage dynode 910i to the tenth-stage dynode 910j.

[0064] In the electron multiplier section 906, a portion of the electrons emitted from the eighth-stage dynode 910h skips the ninth-stage dynode 910i and the tenth-stage dynode 910j and enters the anode 907. For example... Figure 8 As shown in (b), a portion of the electrons emitted from the ninth-stage dynode 910i skips the tenth-stage dynode 10j and enters the anode 907. Then, as... Figure 8 As shown in (c), a portion of the electrons emitted from the tenth-stage dynode 910j deflects near the mesh structure 930 until they are collected at the anode 907. Specifically, a portion of the electrons emitted from the tenth-stage dynode 910j crosses back and forth between the ninth-stage dynode 910i and the tenth-stage dynode 910j multiple times before colliding with the anode 907.

[0065] In contrast, such as Figure 9 As shown in (a), in the electron multiplier 6 involved in the embodiment, a portion of the electrons emitted from the eighth-stage dynode 10h skips the ninth-stage dynode 10i and the tenth-stage dynode 10j and is incident on the anode 7, but is blocked by the partition 20, and the incident is prevented.

[0066] like Figure 9 As shown in (b), a portion of the electrons emitted from the ninth-stage dynode 10i are intended to bypass the tenth-stage dynode 10j and enter the anode 7, but are blocked by the separator 20, thus preventing this entry. The electrons emitted from the ninth-stage dynode 10i pass through the space K formed between the separator 20 and the tenth-stage dynode 10j and enter the tenth-stage dynode 10j. Then, as... Figure 9 As shown in (c), electrons emitted from the tenth stage dynode 10j are collected by the electron collection surface 73 of the anode 7.

[0067] The photomultiplier tube 1 includes a photoelectric surface 3, an N-stage (N=10 here) dynode 10 that multiplies electrons emitted from the photoelectric surface 3, and an anode 7 that collects electrons multiplied by the dynode 10. In the photomultiplier tube 1, the anode 7, which faces the secondary electron emission surface 11j of the tenth-stage dynode 10j (the final stage), extends along this secondary electron emission surface 11j. Therefore, electrons can easily enter the anode 7 from the final-stage dynode 10j. At the same time, the anode 7 does not have an electron passage hole in the electron path from the ninth-stage dynode 10i (the stage before the final stage) to the final-stage dynode 10j, thus preventing electron deflection caused by such a hole. As a result, the timing characteristics originating from the anode 7 can be improved. In particular, by preventing electron deflection, the fall time characteristic of the signal waveform output from the anode 7 can be improved.

[0068] In the photomultiplier tube 1, the anode 7 is positioned between the ninth-stage dynode 10i and the tenth-stage dynode 10j. In this case, it is easy to position the anode 7 close to the tenth-stage dynode 10j, which can improve the electric field strength between the anode 7 and the tenth-stage dynode 10j.

[0069] The photomultiplier tube 1 includes a separator 20 disposed between the ninth-stage dynode 10i and the anode 7, preventing electrons from entering the anode 7 from the ninth-stage dynode 10i. In this case, electrons are prevented from bypassing the tenth-stage dynode 10j from the ninth-stage dynode 10i and entering the anode 7. As a result, the timing characteristics (especially rise time characteristics) of the anode 7 are improved.

[0070] In the photomultiplier tube 1, a potential above the potential of the ninth-stage dynode 10i is applied to the separator 20. In this case, the separator 20 can effectively prevent electrons from entering the anode 7 from the ninth-stage dynode 10i.

[0071] In photomultiplier tube 1, a separator 20 is disposed between the ninth-stage dynode 10i and the tenth-stage dynode 10j. Electrons emitted from the ninth-stage dynode 10i pass through the space K between the separator 20 and the tenth-stage dynode 10j and are incident on the tenth-stage dynode 10j. In this case, the space K between the separator 20 and the tenth-stage dynode 10j can be used to allow electrons to be incident from the ninth-stage dynode 10i to the Nth-stage dynode 10j.

[0072] The inventors have conducted repeated and in-depth research, and have obtained the following insights: Discharge between the dynodes 10 is easily generated from the end of the dynode 10 along its length direction, i.e., the X-direction. Therefore, in the photomultiplier tube 1, the width of the X-direction edge E of the third, fifth, seventh, and ninth dynodes 10c, 10e, 20g, and 10i is smaller than the width of the X-direction edge of the second, fourth, sixth, and eighth dynodes 10b, 10d, 10f, and 10h. Furthermore, the X-direction edge E of the third, fifth, seventh, and ninth dynodes 10c, 10e, 20g, and 10i is contained within the second, fourth, sixth, and eighth dynodes 10b, 10d, 10f, and 10h. This allows the opposing dynodes 10 to be brought closer to each other, thereby increasing the electric field strength between stages. It also ensures that the X-direction ends of the third, fifth, seventh, and ninth stage dynodes 10c, 10e, 20g, and 10i are kept away from the X-direction ends of the second, fourth, sixth, and eighth stage dynodes 10b, 10d, 10f, and 10h, thus preventing discharge.

[0073] That is, in the photomultiplier tube 1, the m-th stage dynode 10 is arranged opposite to the (m-1)-th stage dynode 10. In the length direction (X direction) of the dynode 10, the width of the end edge E of the (m-1)-th stage dynode 10 is smaller than the width of the (m-1)-th stage dynode 10. In the X direction, this end edge E of the m-th stage dynode 10 is contained within the inner side of the (m-1)-th stage dynode 10. Therefore, it is possible to prevent discharge between the dynodes 10 while improving timing characteristics. In other words, reducing the electrode distance between the dynodes 10 used to prevent discharge can increase the electric field strength and improve timing characteristics.

[0074] In photomultiplier tube 1, the dynode 10 has an arc-shaped cross-section along the YZ plane. Furthermore, when viewed from the X direction, the edge E of the fifth, seventh, and ninth dynodes 10e, 10g, and 10i are nested structures with widths different from those of the fourth, sixth, and eighth dynodes 10d, 10f, and 10h, respectively. The edge E of the fifth, seventh, and ninth dynodes 10e, 10g, and 10i enters the fourth, sixth, and eighth dynodes 10d, 10f, and 10h, respectively. This prevents discharge and brings the fourth and fifth dynodes 10d and 10e closer together, increasing the electric field strength between them. It also prevents discharge and brings the sixth and seventh dynodes 10f and 10g closer together, increasing the electric field strength between them. Finally, it prevents discharge and brings the eighth and ninth dynodes 10h and 10i closer together, increasing the electric field strength between them.

[0075] Furthermore, by setting the adjacent dynodes 10, 10 in a nested structure, electrons with extremely long or short transit times can be cut off (it can be configured such that electrons with extremely long or short transit times hit the surface of the dynode 10 opposite to the secondary electron emission surface 11), and the electron group collected by the anode 7 becomes an electron group with a small transit time difference, which can easily improve the time characteristics.

[0076] Furthermore, by making at least the adjacent upstream dynodes 10, 10 in the N-stage dynode 10 a nested structure, electrons with extremely long or short transit times can be cut off before electron multiplication. This also prevents ions generated by the increase in electrons inside the dynode 10 from being fed back to the photoelectric surface 3.

[0077] In the photomultiplier tube 1, in the X direction, the width of the first-stage dynode 10a is greater than the width of the second to tenth-stage dynodes 10b to 10j. In the X direction, the second to tenth-stage dynodes 10b to 10j form a nested structure contained within the first-stage dynode 10a. In this case, by moving the X-direction ends of the second to tenth-stage dynodes 10b to 10j away from the X-direction end of the first-stage dynode 10a, the distance between these ends can be ensured, thus preventing discharge.

[0078] Figure 10 (a) is a graph showing the simulation results of the rise time for the comparative example and the embodiment. Figure 10 (b) is a graph showing the simulation results of the fall time for the comparative example and the embodiment. The rise time is the time it takes for the output pulse peak to reach 90% from 10%. The fall time is the time it takes for the output pulse peak to return to 10% from 90%. It can be said that shorter rise and fall times indicate better time characteristics. The comparative example corresponds to the electron multiplier 906 (see reference 906). Figure 8 ), the embodiment corresponds to electron multiplier 6 (refer to Figure 9 The graph in the figure compares the values ​​of 10j and 910j at the 10th stage dynode with the values ​​of 7 and 907 at the anode. For example... Figure 10 (a) and Figure 10 As shown in (b), in the comparative example, during the electron multiplication process from the tenth stage dynode 10j to the anode 7, both the rise time and fall time become longer (deteriorate). In contrast, in the embodiment, it can be confirmed that both the rise time and fall time can be maintained.

[0079] Figure 11 (a) is a graph showing the measured values ​​of the output signal from anode 907 in the comparative example. Figure 11 (b) is a graph representing the measured values ​​of the output signal from anode 7 in the embodiment.

[0080] exist Figure 11 (a) and Figure 11 In (b), the timelines correspond to each other. For example... Figure 11 (a) and Figure 11 As shown in (b), it can be confirmed that in the embodiment, compared with the comparative example, a significant improvement in the rise time and fall time of the anode 7 can be achieved.

[0081] It should be noted that in this embodiment, all stages N of the multiplier 10 are set to 10, but N is not particularly limited and can be an integer greater than or equal to 2. In this embodiment, the m of the stages of the multiplier 10 with the smallest width is set to 3, 5, 7, or 9 (odd-numbered stages), but m is not particularly limited and can be an even-numbered stage, as long as it is an integer greater than or equal to 2 and less than or equal to N.

[0082] In this embodiment, the edge E of the fifth, seventh, and ninth stage dynodes 10e, 10g, and 10i (of the third, fifth, seventh, and ninth stages dynodes 10c, 10e, 10g, and 10i with smaller widths) is placed in the upstream dynode 10, but this is not a limitation. All edge E of the third, fifth, seventh, and ninth stage dynodes 10c, 10e, 10g, and 10i may be placed in the upstream dynode 10. Alternatively, any one edge E of the fifth, seventh, and ninth stage dynodes 10e, 10g, and 10i may be placed in the upstream dynode 10. That is, at least one edge E of the plurality of dynodes 10 with smaller widths may be placed in the upstream dynode 10. Alternatively, the edge E of the fifth, seventh, and ninth stage dynodes 10e, 10g, and 10i may not be placed in the upstream dynode 10. That is, the N-stage dynodes 10 can also be configured such that adjacent dynodes 10, 10 are separated from each other when viewed from the X direction.

[0083] In this embodiment, the width of the edge E of the m-th stage dynode 10 is smaller than the width of the (m-1)-th stage dynode 10. Therefore, for example, the width of the dynode 10 other than the edge E of the m-th stage dynode 10 can also be larger than the width of the (m-1)-th stage dynode 10.

[0084] In this embodiment, in the sidewalls 13W of the fifth, seventh, and ninth dynodes 10e, 10g, and 10i of the upstream dynode 10, a retaining sheet (not shown) for holding to the insulating support substrate can be provided on the side away from the upstream dynode 10. In this case, the timing characteristics can be improved and discharge between the dynodes 10 can be further prevented.

[0085] Furthermore, in the field of photomultiplier tubes, improving the timing characteristics caused by the anode is synonymous with suppressing the deterioration of timing characteristics caused by stray electrons and / or deviations in transit paths; therefore, suppressing this deterioration becomes important. In this regard, as described above, the photomultiplier tube 1 of this embodiment can effectively suppress the deterioration of timing characteristics caused by stray electrons and / or deviations in transit paths, and is therefore particularly effective.

[0086] The present disclosure is not limited to the embodiments described above.

[0087] Figure 12 (a) is a perspective view showing a portion of the electron multiplier 106 involved in the first modified example in cross-section. Figure 12 As shown in (a), the electron multiplier 106 has a dynode 110j replacing the dynode 10j of the tenth stage (see reference). Figure 3 ), equipped with anode 107 replacing anode 7 (refer to Figure 3 It also has a mesh electrode 130, which is different from the above-described embodiments.

[0088] The tenth-stage dynode 110j includes a straight portion 11L with a straight cross-section along the YZ plane and a curved portion 11R that bends along the YZ plane. The curved portion 11R extends in a manner that bends from the end of the straight portion 11L toward the ninth-stage dynode 10i. The other structures of the dynode 110j are configured in the same way as those of the dynode 10j.

[0089] The anode 107 is L-shaped in cross-section along the YZ plane. The outer surface of the tenth-stage dynode 110j side of the anode 107 has an electron collecting surface 173. The electron collecting surface 173 faces the secondary electron emission surface 111j of the tenth-stage dynode 110j, and at least a portion extends along this secondary electron emission surface 111j. Here, the electron collecting surface 173 extends in a planar shape, mimicking the secondary electron emission surface 111j of the straight portion 11L. Otherwise, the anode 107 is constructed similarly to the anode 7.

[0090] The mesh electrode 130 is disposed on the electron path from the tenth-stage dynode 110j toward the anode 107. That is, the mesh electrode 130 is disposed between the anode 107 and the tenth-stage dynode 110j. The mesh electrode 130 facilitates the extraction of electrons from the tenth-stage dynode 110j. The mesh electrode 130 is disposed close to the secondary electron emission surface 111j of the tenth-stage dynode 110j. The mesh electrode 130 includes a plurality of electron-passing apertures 130H for allowing electrons to pass through.

[0091] A potential higher than that of the tenth-stage dynode 110j is applied to the mesh electrode 130. The mesh electrode 130 is preferably not electrically connected to the anode 107. The mesh electrode 130 constitutes an extraction electrode for electrons drawn from the tenth-stage dynode 110j, improving output linearity (dynamic range). The mesh electrode 130 improves the time characteristics originating from the anode 107 by increasing the electric field strength between the anode 107 and the tenth-stage dynode 110j, thereby accelerating electrons flying from the tenth-stage dynode 110j towards the anode 107.

[0092] In this first modification, the aforementioned effect of improving the timing characteristics originating from the anode 107 is also achieved. Furthermore, the aforementioned effect of improving timing characteristics and preventing discharge between the dynodes 10 is also achieved. In this first modification, by promoting electron extraction from the tenth-stage dynode 110j through the mesh electrode 130, the output linearity (dynamic range) can be improved.

[0093] Furthermore, in the first modification, a potential higher than that of the tenth-stage dynode 110j is applied to the mesh electrode 130. In this case, the mesh electrode 130 can efficiently extract electrons. In the first modification, the mesh electrode 130 is used as the extraction electrode. In this case, the mesh electrode 130 can be used to facilitate the extraction of electrons from the tenth-stage dynode 110j.

[0094] Furthermore, in the first modification, the mesh electrode 130 is not electrically connected to the anode 107, but it can also be electrically connected to the anode 107. In this case, the mesh electrode 130 is not an electrode that collects electrons that can be used as signal current, and it does not function as the anode 107. Moreover, the number of electrons colliding with the mesh electrode 130 is not zero, so there is a possibility that the signal caused by the electrons incident on the mesh electrode 130 overlaps with the output of the anode 107. However, the probability of electrons drawn from the 10th stage dynode 110j colliding with the mesh electrode 130 is low (very few electrons collide), so the anode 107 has little effect on the timing characteristics. In this way, by electrically connecting the mesh electrode 130 to the anode 107, the number of components can be reduced, and the ease of assembly can be improved.

[0095] Figure 12 (b) is a perspective view showing a portion of the electron multiplier 206 involved in the first modified example in cross-section. Figure 12 As shown in (b), the electron multiplier 206 differs from the embodiment described above in that it does not have a tenth-stage multiplier 10j (see Figure 10). Figure 3 ), replacing the ninth stage multiplier 10i (refer to Figure 3 It features a 210i multiplier electrode, replacing the anode 7 (see reference). Figure 3 It has an anode 207, replacing the partition 20 (see reference). Figure 3 It has a partition 220.

[0096] In the electron multiplier section 206, N=9, and it has nine dynodes 10. The ninth dynode 210i includes a straight portion 21L with a straight cross-section along the YZ plane and a curved portion 21R that bends along the YZ plane. The curved portion 21R extends from the end of the straight portion 21L toward the eighth dynode 10h. The other structures of the dynode 210j are configured similarly to those of the dynode 10i.

[0097] Anode 207 is disposed between the eighth-stage dynode 10h and the ninth-stage dynode 210i. A cross-section of anode 207 along the YZ plane is formed along the ninth-stage dynode 210i. The outer surface of anode 207 on the ninth-stage dynode 210i side has an electron collecting surface 273. The electron collecting surface 273 faces the secondary electron emission surface 211i of the ninth-stage dynode 210i, and at least a portion extends along the secondary electron emission surface 211i. Otherwise, anode 207 is configured similarly to anode 7.

[0098] A separator 220 is disposed between the eighth-stage dynode 10h and the anode 207. The separator 220 prevents electrons from entering the anode 207 from the eighth-stage dynode 10h. The separator 220 is also disposed between the eighth-stage dynode 10h and the ninth-stage dynode 210i. The separator 220 is a flat plate extending in the X direction. The separator 220 is integrally formed with the ninth-stage dynode 210i. The separator 220 is continuous with the end of the curved portion 21R of the ninth-stage dynode 210i. An opening 220H is formed in the separator 220, extending through its thickness direction. The opening 220H forms a space K. Electrons emitted from the eighth-stage dynode 10h pass through the space K in the separator 220 and enter the ninth-stage dynode 210i. The separator 220 is applied with a potential higher than that of the eighth-stage dynode 10h. In addition, partition 220 is constructed in the same manner as partition 20.

[0099] In this second modification, the aforementioned effect of improving the timing characteristics originating from the anode 207 is also achieved. Furthermore, the aforementioned effect of improving timing characteristics and preventing discharge between the dynodes 10 is also achieved. Additionally, in this second modification, the separator 220 is integrally formed with the final stage dynode 210i, thus the separator 220 can be easily provided using the final stage dynode 210i.

[0100] Figure 13 This is a perspective view showing a portion of the electron multiplier 306 involved in the third modified example. Figure 14 This is a diagram showing a portion of the electron multiplication unit 306 involved in the third modified example when viewed from the Y direction. (See diagram below.) Figure 13 and Figure 14 As shown, the electron multiplier section 306 has dynodes 310e, 310g, and 310i replacing the dynodes 10e, 10g, and 10i of the fifth, seventh, and ninth stages (see reference). Figure 3 This differs from the implementation method described above.

[0101] The fifth-stage dynode 310e extends obliquely relative to the YZ plane, with its sidewalls 31W at both ends in the X direction expanding outwards from the fourth-stage dynode 10d. The width of the fifth-stage dynode 310e is smallest at the end edge E1 on the side of the fourth-stage dynode 10d, and increases with distance from the fourth-stage dynode 10d. The end edge Z1 on the opposite side of end edge E1 corresponds to the width of the fourth-stage dynode 10d. The other structures of the dynode 310e are configured in the same way as those of the dynode 10e.

[0102] The seventh-stage dynode 310g extends obliquely relative to the YZ plane, with its sidewalls 32W at both ends in the X direction expanding outwards from the sixth-stage dynode 10f. The width of the seventh-stage dynode 310g is smallest at the end edge E2 on the side of the sixth-stage dynode 10f, and increases as it moves away from the sixth-stage dynode 10f. The end edge Z2 on the opposite side of end edge E2 corresponds to the width of the sixth-stage dynode 10f. The other structures of the dynode 310g are configured in the same way as those of the dynode 10g.

[0103] The ninth-stage dynode 310i extends obliquely relative to the YZ plane, with its sidewalls 33W at both ends in the X direction expanding outwards from the eighth-stage dynode 10h. The width of the ninth-stage dynode 310i is smallest at the end edge E3 on the side of the eighth-stage dynode 10h, and increases with distance from the eighth-stage dynode 10h. The end edge Z3 on the opposite side of end edge E3 corresponds to the width of the eighth-stage dynode 10h. The other structures of the dynode 310i are configured in the same way as those of the dynode 10i.

[0104] In this third variation, the aforementioned effect of improving the timing characteristics of the anode 207 is also achieved. Furthermore, the aforementioned effect of improving timing characteristics and preventing discharge between the dynodes 10 is also achieved.

[0105] Figure 15 This is a perspective view showing a portion of the electron multiplier 406 involved in the third variation. Figure 16 This is a diagram showing a portion of the electron multiplication unit 406 involved in the fourth modified example when viewed from the Y direction. Figure 17 This is a diagram showing a portion of the electron multiplication unit 406 involved in the fourth modified example when viewed from the X direction. (See diagram below.) Figure 15 , Figure 16 and Figure 17As shown, the electron multiplier 406 has a dynode 410g replacing the dynode 10g of the seventh stage (see reference). Figure 3 This differs from the implementation method described above.

[0106] The width of the seventh-stage dynode 410g in the X direction is constant, and the sidewall 13W extends along the YZ plane. The width of the seventh-stage dynode 410g is equal to the width of the sixth-stage dynode 10f. That is, in the fourth variation, the k-th stage (k is an integer other than 2 and N, where k = 7) dynode 10 is arranged opposite to the (k-1)-th stage dynode 10, and the width of the k-th stage dynode 10 in the X direction is equal to the width of the (k-1)-th stage dynode 10.

[0107] The edge E4 of the seventh-stage dynode 410g does not enter the sixth-stage dynode 10f. Viewed from the X direction, the seventh-stage dynode 410g is configured separately from the sixth-stage dynode 10f. That is, the nested structure described above is adopted only in at least one of the multiple interstages (interstages of dynode 10) among the multiple dynodes 10 included in the electron multiplication section 406 (here, the interstages of the fourth and fifth-stage dynodes 10d and 10e, and the interstages of the eighth and ninth-stage dynodes 10h and 10i). The other structures of the dynode 410g are configured in the same way as those of the dynode 10g.

[0108] In this fourth variation, the aforementioned effect of improving the timing characteristics originating from the anode 207 is also achieved. Furthermore, the aforementioned effect of improving timing characteristics and preventing discharge between the dynodes 10 is also achieved.

[0109] Furthermore, in the fourth variation, the k-th stage dynode 410g is configured opposite to the (k-1)-th stage dynode 410f. In the X direction, the width of the k-th stage dynode 410g is equal to the width of the (k-1)-th stage dynode 410f. In this case, the electron arrival efficiency (so-called interstage efficiency) of both the k-th and (k-1)-th stage dynodes 410f can be improved. In interstages where time characteristics deteriorate, a nested structure is used to improve time; in other interstages, electron arrival efficiency can be improved. Both time characteristics and electron multiplication factor can be balanced.

[0110] Figure 18 This is a cross-sectional view showing the electron multiplier 606 involved in the fifth modified example. For example... Figure 18 As shown, the electron multiplication section 606 has dynodes 610c, 610e, 610g, and 610i replacing the dynodes 10c, 10e, 10g, and 10i of the third, fifth, seventh, and ninth stages (see reference). Figure 3 This differs from the implementation method described above.

[0111] The widths of the dynodes 10b, 610c, 10d, 610e, 10f, 610g, 10h, 610i, and 10j in stages two through ten are equal. The dynodes 610c, 610e, 610g, and 610i in stages three, five, seven, and nine are not part of the dynodes 10b, 610d, 10f, and 10h in stages two, four, six, and eight, respectively, and are configured separately from them. The other configurations of the dynodes 610c, 610e, 610g, and 610i in stages three, five, seven, and nine are the same as those of dynodes 10c, 10e, 10g, and 10i.

[0112] In this fifth variation, the aforementioned effect of improving the time characteristics caused by anode 7 is also achieved.

[0113] In the above embodiments and modifications, the entire region of the electron collecting surfaces 73, 173, and 273 of the anodes 7, 107, and 207 may not extend along the secondary electron emission surface 11 of the Nth-stage dynode 10, as long as at least a portion of the electron collecting surfaces 73, 173, and 273 of the anodes 7, 107, and 207 extends along the secondary electron emission surface 11 of the Nth-stage dynode 10. In the above embodiments and modifications, nested structures can be alternately applied from the upstream side to the downstream side between the multiple stages of the Nth-stage dynode 10.

[0114] In the above embodiments and variations, partitions 20 and 220 are provided. However, as long as they are components that constitute the wall portion that prevents electrons from entering the anode 7 from the N-1th stage dynode 10, components of various shapes can be used instead of partitions 20 and 220.

[0115] In the structures of the above embodiments and modifications, the materials and shapes are not limited to those described above, and a wide variety of materials and shapes can be used. Furthermore, the structures of the above embodiments and modifications can be arbitrarily applied to structures in other embodiments or modifications.

[0116] Explanation of reference numerals in the attached figures

[0117] 1… Photomultiplier tube, 3… Photoelectric surface, 7, 107, 207… Anode, 10, 10a~10j, 110j, 210i, 310e, 310g, 310i, 410g, 610c, 610e, 610g, 610i… Multiplier electrode, 11, 11j, 111j, 211i… Secondary electron emission surface, 20, 220… Partition (wall), 73, 173, 273… Electron collection surface, 130… Mesh electrode (lead-out electrode), E, ​​E1~E4… Edge, K… Space.

Claims

1. A photomultiplier tube, wherein, Features: photoelectric surface; The Nth-order multiplier of electrons emitted from the photoelectric surface, wherein N is an integer greater than or equal to 2; and The anode collects electrons multiplied by the multiplying electrode. The anode, An electron collecting surface has an electron-collecting surface that is opposite to the secondary electron emission surface of the Nth stage dynode and at least a portion of which extends along the secondary electron emission surface. There is no electron passage hole in the electron path from the (N-1)th stage dynode to the Nth stage dynode.

2. The photomultiplier tube according to claim 1, wherein, The anode is positioned between the (N-1)th stage dynode and the Nth stage dynode.

3. The photomultiplier tube according to claim 1 or 2, wherein, It has a wall portion disposed between the (N-1)th stage dynode and the anode, which prevents electrons from entering the anode from the (N-1)th stage dynode.

4. The photomultiplier tube according to claim 3, wherein, The wall portion is applied with a potential higher than that of the (N-1)th level pyrolysis electrode.

5. The photomultiplier tube according to claim 3 or 4, wherein, The wall portion is integrally formed with the multiplier electrode of the Nth stage.

6. The photomultiplier tube according to claim 3 or 4, wherein, The wall portion is disposed between the (N-1)th stage dynode and the Nth stage dynode. Electrons emitted from the (N-1)th stage dynode enter the Nth stage dynode through the space between the wall and the Nth stage dynode.

7. The photomultiplier tube according to claim 1 or 2, wherein, It has an extraction electrode disposed between the anode and the Nth stage dynode to facilitate the extraction of electrons from the Nth stage dynode.

8. The photomultiplier tube according to claim 7, wherein, The lead-out electrode is applied with a higher potential than that of the multiplier electrode of the Nth stage.

9. The photomultiplier tube according to claim 7, wherein, The lead-out electrode is a mesh electrode.

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