JP2006127971A - Photodetector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photodetector in which air tightness and fusion-bonding strength of a flange part of a side tube against a photoreceiving face plate can be enhanced. <P>SOLUTION: A photomultiplier tube (photodetector) 1 has a sealing container 8 formed by a metallic side tube 2, the photoreceiving face plate 3, a stem 5, and a ring-shaped side tube 7. In the inside of the sealing container 8, a photoelectric face 4 in order to convert the light incident through the photoreceiving face plate 3 to electron, the electron multiplier part 9 in order to multiply electrons discharged from this photoelectric face 4, and an anode 12 that takes out the electrons multiplied by this electron multiplier part 9 as an output signal are arranged. The photoreceiving face plate 3 is fused and joined via a metal oxide membrane to the outer face (upper face) 51a and the inner edge face 51b of the flange part 51 formed on the side tube 2. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a photodetector such as a photomultiplier tube using a photoelectric effect.

  One of the photodetectors is a photomultiplier tube. As a photomultiplier tube, a vacuum-sealed container is formed by providing a light-receiving face plate at one end of a cylindrical side tube and a stem at the other end, and a photoelectron is formed on the inner surface of the light-receiving face plate. A discharge surface (photocathode) is provided, and a plurality of dynodes and anodes are stacked to face the photocathode, and a plurality of stem pins respectively connected to the dynodes and anodes of each step are provided from the inside of the sealed container. The light incident through the light receiving face plate is converted into electrons on the photocathode, and the electrons emitted from the photocathode are given a predetermined voltage via each stem pin. A so-called head-on type photomultiplier tube is known in which multiplication is performed sequentially at each applied dynode, and electrons that have been multiplied and reach the anode are taken out as electrical signals through an anode pin that is one of the stem pins. Yes.

In such a photomultiplier tube, there is one in which a glass light-receiving face plate is joined to a flange portion provided at one end portion of a metal side tube forming a vacuum sealed container by thermal fusion (for example, Patent Document 1).
Japanese Patent Laid-Open No. 10-12185 (FIG. 1)

  However, in the photomultiplier tube as described above, the bonding strength (fusion strength) at the fusion interface between the flange portion of the side tube and the light receiving face plate is high, and the vacuum tightness between the two is excellent. It is desired.

  The present invention has been made to solve such a problem, and provides a photodetector capable of improving the fusion strength and airtightness between the flange portion of the side tube and the light receiving face plate. Objective.

  The present invention relates to a sealed container having a conductive side tube and a light receiving surface plate joined to one end of the side tube, and a photoelectric surface provided in the sealed container for converting light incident through the light receiving surface plate into electrons. And an anode for taking out the electrons emitted from the photocathode as an output signal, and a flange portion protruding inside the side tube at one end of the side tube. The light-receiving face plate provided is fusion-bonded to the flange portion through an oxide film.

  When manufacturing such a photodetector, for example, a flange portion of a metal side tube having conductivity and a glass light receiving face plate are fused and joined. At this time, by heating the flange portion with an oxide film interposed between the flange portion and the light receiving face plate, the glass and the oxide film diffuse to each other after the melting point of the light receiving face plate (glass) is exceeded. Thus, a bonding layer (diffusion layer) in which glass and metal are mixed is formed. Due to this diffusion layer, the adhesion at the fusion interface between the flange portion and the light receiving face plate is sufficiently increased. As a result, the bonding strength between the flange portion and the light receiving face plate is increased, and the vacuum tightness between the flange portion and the light receiving face plate is also increased.

  Preferably, the light receiving face plate is formed so as to enter a space defined by the inner edge surface of the flange portion and the main body portion fused and bonded to the outer surface of the flange portion via an oxide film. And a convex portion fused and bonded to the inner edge surface of the flange portion via an oxide film. By providing the convex portion on the light receiving face plate in this way, the fusion length between the flange portion of the side tube and the light receiving face plate is increased accordingly. Thereby, the joint strength and vacuum tightness of a flange part and a light-receiving surface board become higher.

  At this time, it is preferable that the light receiving face plate is formed by heating the side tube in a state where a glass flat plate is placed on the outer surface of the flange portion having an oxide film formed on the surface. When the side tube is heated with the glass flat plate placed on the outer surface of the flange portion of the side tube, the glass flat plate is melted, and accordingly, the central portion of the glass flat plate is in the space defined by the inner edge surface of the flange portion. It is dropped and a convex part is formed. Thus, the light-receiving surface plate which has a convex part can be formed easily and cheaply using one glass flat plate.

  In addition, a conductive thin film is formed on the front end surface of the convex portion and the inner surface of the flange portion, and a conductive thin film formed on the front end surface of the convex portion and a conductive thin film formed on the inner surface of the flange portion, Are connected by wire bonding, and the photocathode is preferably formed so as to cover the conductive thin film at least at the tip end surface of the convex portion. When making a photodetector, after the light-receiving face plate having the convex portion as described above is fusion-bonded to the flange portion of the side tube, the conductive thin film extends from the edge of the front end surface of the convex portion to the inner surface of the flange portion. In addition, a photocathode is formed at least on the tip surface of the convex portion. Here, the photocathode formed on the front end surface of the convex portion is formed so as to cover the conductive thin film formed on the edge portion of the front end surface of the convex portion. In this case, before forming the conductive thin film and the photocathode, it is necessary to remove an unnecessary oxide film formed on the inner surface of the flange portion by, for example, chemical polishing. However, when such a chemical polishing process is performed, a depression is generated at the boundary between the flange portion and the convex portion of the light receiving face plate. Therefore, when a conductive thin film is formed on the tip surface of the convex portion and the inner surface of the flange portion. In some cases, the conductive thin film formed on the front end surface of the convex portion and the conductive thin film formed on the inner surface of the flange portion are not electrically connected. Therefore, by connecting the conductive thin film formed on the tip surface of the convex portion and the conductive thin film formed on the inner surface of the flange portion by wire bonding, the electrical connection between them can be stably secured. Become so.

  Here, if it further includes an electron multiplying unit that is provided in a sealed container of the photodetector and that multiplies electrons emitted from the photocathode and enters the anode, a suitable photomultiplier that achieves the above-described effects can be obtained. A tube is obtained.

  Moreover, if the scintillator which is arrange | positioned on the outer side of the light-receiving surface plate of the said photodetector and converts radiation into light and discharge | releases is further provided, the suitable radiation detection apparatus which has the said effect | action will be obtained.

  According to the present invention, since the light receiving face plate is fusion bonded to the flange portion of the side tube via the oxide film, the fusion strength and airtightness between the flange portion and the light receiving face plate are improved.

  Hereinafter, preferred embodiments of the photodetector according to the present invention will be described with reference to the drawings. In the following description, terms such as “upper” and “lower” are for convenience based on the state shown in the drawings. Moreover, in each figure, the same code | symbol is attached | subjected to the same or an equivalent part, and the overlapping description is abbreviate | omitted.

  1 and 2 are a plan view and a bottom view showing a photomultiplier tube as an embodiment of the photodetector according to the present invention, and FIG. 3 is a sectional view taken along line III-III in FIG. 1 to 3, the photomultiplier tube 1 is configured as a device for emitting electrons by light incident from the outside, multiplying the electrons, and outputting them as a signal.

  The photomultiplier tube 1 has a metal side tube 2 having a substantially cylindrical shape. The side tube 2 is made of, for example, an alloy of iron, nickel, and kovar metal. One end portion (upper end portion) of the side tube 2 is provided with an annular flange portion 51 projecting inside the side tube 2, and the other end portion (lower end portion) of the side tube 2 is disposed outside the side tube 2. An overhanging annular flange 52 is provided.

  A light receiving face plate 3 made of glass is airtightly fixed to the upper opening end of the side tube 2, and a photoelectron emission surface (hereinafter referred to as “electron emission surface”) for converting light incident through the light receiving face plate 3 into electrons on the inner surface of the light receiving face plate 3. , Photocathode) 4 is formed. The light receiving face plate 3 and the photocathode 4 will be described in detail later.

  A disc-shaped stem 5 is disposed at the lower open end of the side tube 2. Here, in the stem 5, a side that becomes a vacuum when the sealed container 8 of the photomultiplier tube 1 is formed is defined as an inner side (upper side). A plurality (15) of conductive stem pins 6 that are spaced apart from each other in the circumferential direction are inserted into the stem 5 in an airtight manner at substantially circular positions. Specifically, the stem 5 includes a base material 14, an upper presser material 15 joined to the upper side (inner side) of the base material 14, and a lower presser material 16 joined to the lower side (outer side) of the base material 14. And a three-layer structure formed by fusion bonding. The base material 14 is a disk-shaped member made of insulating glass whose main component is Kovar, for example, and the upper presser material 15 and the lower presser material 16 are obtained by adding, for example, alumina powder to Kovar. This is a disk-shaped member made of insulating glass having a higher melting point than the base material 14. The base material 14 and each stem pin 6 are fused. The structure of the stem 5 is not particularly limited to the three-layer structure as described above, and may be a single-layer structure including only a base material, a two-layer structure including a base material and a pressing material, or the like.

  A metal ring-shaped side tube 7 is airtightly fixed to the stem 5 so as to surround the stem 5 from the side. Specifically, the ring-shaped side tube 7 is fused to the base material 14 of the stem 5. At one end (upper end) of the ring-shaped side tube 7, an annular flange portion 7 a projecting outside the ring-shaped side tube 7 is provided. By welding the flange portion 7a and the flange portion 52 formed at the lower end portion of the side tube 2, the side tube 2 and the ring-shaped side tube 7 are fixed in an airtight manner.

  The side tube 2, the light receiving face plate 3, the stem 5, and the ring-shaped side tube 7 form a sealed container 8 whose inside is kept in a vacuum state. In such a sealed container 8, an electron multiplier 9 for multiplying electrons emitted from the photocathode 4 is accommodated. The electron multiplier section 9 is formed in a block shape by laminating a thin plate-like dynode 10 having a large number of electron multiplier holes in a plurality of stages (in this embodiment, 10 stages), and is installed on the upper surface of the stem 5. . A dynode connection piece 10c that protrudes outward is formed at a predetermined edge of each dynode 10, and a tip portion of a predetermined stem pin 6 inserted into the stem 5 is formed on the lower surface side of each dynode connection piece 10c. It is fixed by welding. Thereby, each dynode 10 and each stem pin 6 are electrically connected.

  Further, in the sealed container 8, a flat focusing electrode 11 for converging and guiding electrons emitted from the photocathode 4 to the electron multiplier 9 between the electron multiplier 9 and the photocathode 4. Is installed. Further, a flat plate anode (anode) 12 is stacked on the upper stage of the final stage dynode 10b for taking out the electrons emitted from the final stage dynode 10b as an output signal. Has been.

  Protruding pieces 11a projecting outward are formed at the four corners of the converging electrode 11, and predetermined stem pins 6 are welded and fixed to the projecting pieces 11a, whereby the stem pin 6 and the converging electrode 11 are electrically connected. Has been made. An anode connecting piece 12a protruding outward is also formed at a predetermined edge of the anode 12, and an anode pin 13 which is one of the stem pins 6 is welded and fixed to the anode connecting piece 12a. And the anode 12 are electrically connected. When a predetermined voltage is applied to the electron multiplier 9 and the anode 12 by each stem pin 6 connected to a power supply circuit (not shown), the photocathode 4 and the convergence electrode 11 are set to the same potential, and each dynode 10 The higher potential is set from the upper level to the lower level in the stacking order. The anode 12 is set to a higher potential than the final dynode 10b.

In the photomultiplier tube 1 configured as described above, when light (hν) is incident on the photocathode 4 from the light receiving face plate 3 side, light is photoelectrically converted on the photocathode 4 and electrons (e ^- ) Is released. The emitted electrons are converged to the first stage dynode 10 a by the focusing electrode 11. Then, the electrons are sequentially multiplied in the electron multiplying unit 9, and secondary electron groups are emitted from the last dynode 10b. The secondary electron group is guided to the anode 12 and output to the outside through the anode pin 13.

  The upper structure of the photomultiplier tube 1 including the light receiving face plate 3 and the photocathode 4 will be described in more detail with reference to FIGS.

  The light-receiving face plate 3 includes a main body portion 3a that is fusion-bonded to an outer surface (upper surface) 51a of a flange portion 51 formed in the side tube 2, and an inner edge surface 51b of the flange portion 51 that is integrated with the main body portion 3a. And a convex portion 3b that is fusion-bonded to the inner edge surface 51b of the flange portion 51. The inner edge surface 51b is a surface substantially perpendicular to the upper surface 51a. The upper surface of the light receiving surface plate 3 and the lower surface of the light receiving surface plate 3, that is, the tip surface P of the convex portion 3b are substantially flat. Further, the tip surface P of the convex portion 3 b is substantially flush with the inner surface 51 c of the flange portion 51.

  A metal oxide film (for example, an iron oxide film) 53 is formed on the upper surface 51 a and the inner edge surface 51 b of the flange portion 51. A “metal oxide film” is a film-like metal oxide layer formed by combining an element contained in a workpiece base material with oxygen when exposed to oxygen or a heated atmosphere. Accordingly, the main body 3 a of the light receiving surface plate 3 is fused to the upper surface 51 a of the flange portion 51 via the metal oxide film 53, and the convex portion 3 b of the light receiving surface plate 3 is connected to the inner edge of the flange portion 51 via the metal oxide film 53. It is fused to the surface 51b. In the side tube 2, the metal oxide film 53 is not formed on the surface of the region other than the upper surface 51 a and the inner edge surface 51 b of the flange portion 51 joined to the light receiving surface plate 3.

  The photocathode 4 is formed on the tip surface P of the convex portion 3 b and the inner surface 51 c of the flange portion 51 via a conductive thin film (for example, an aluminum vapor deposition film) 54. The conductive thin film 54 is formed over the periphery of the inner surface of the side tube 2 and the lower surface of the light receiving surface plate 3. For this reason, the photocathode 4 is formed on the surface of the conductive thin film 54 on the inner peripheral surface 51c of the flange portion 51 and the peripheral portion of the lower surface of the light receiving face plate 3 (tip surface P of the convex portion 3b), and the convex portion 3b. The photocathode 4 is directly formed on the surface of the light receiving surface plate 3 (the region where the conductive thin film 54 is not formed on the tip surface P of the convex portion 3b). The surface directly formed on the surface of the light receiving surface plate 3 is the effective surface of the photocathode 4.

  A recess 55 is formed at a boundary portion between the inner edge surface 51b of the flange portion 51 and the convex portion 3b. The recess 55 is generated by removing an unnecessary metal oxide film formed on the inner surface 51c of the flange portion 51 by chemical polishing (described later). When the conductive thin film 54 and the photocathode 4 are sequentially formed in this state, the conductive thin film 54 and the conductive thin film 54 that should be formed at the boundary between the inner edge surface 51b of the flange portion 51 and the convex portion 3b in the recess 55. The photocathode 4 enters. Therefore, between the conductive thin film 54 (referred to as a thin film 54a) formed on the tip surface P of the convex portion 3b and the conductive thin film 54 (referred to as a thin film 54b) formed on the inner surface 51c of the flange portion 51. In some cases, there is no electrical connection. For this reason, the thin films 54a and 54b are electrically connected by being connected (wire bonding) with the wire 56.

  Next, a method of attaching the light receiving face plate 3 to the flange portion 51 of the side tube 2 and further forming the photocathode 4 will be described. First, as shown in FIG. 5A, a side tube 2 and a glass flat plate 57 serving as a base of the light receiving face plate 3 are prepared. Then, a metal oxide film 53 is formed on the entire surface of the side tube 2 using, for example, an electric furnace.

  Subsequently, as shown in FIG. 5B, a glass flat plate 57 is placed on the upper surface 51 a of the flange portion 51 of the side tube 2. And the side pipe | tube 2 is heated using the melt | fusion jig etc. which are not shown in figure. In addition, as a heating method of the side tube 2, induction heating such as high-frequency heating is employed, for example.

  When the side tube 2 is heated in this way, the glass flat plate 57 melts from a portion close to the flange portion 51. As a result, as shown in FIG. 5C, the central portion of the glass flat plate 57 (the portion excluding the region in contact with the upper surface 51a of the flange portion 51) is dropped in the space defined by the inner edge surface 51b of the flange portion 51. The upper surface 51a and inner edge surface 51b of the flange portion 51 and the glass flat plate 57 are fused. As a result, the light-receiving face plate 3 is formed which includes the main body part 3 a fused to the upper surface 51 a of the flange part 51 and the convex part 3 b fused to the inner edge face 51 b of the flange part 51.

  By using the melting / dropping of the glass flat plate 57 by heating the side tube 2 as described above, the light-receiving face plate 3 having the convex portions 3b can be easily and inexpensively made using only one glass flat plate 57. Can do. Further, since the light-receiving face plate 3 having the convex portions 3b is formed as described above, it is fusion bonded to the flange portion 51 of the side tube 2, so that the manufacturing process of the photomultiplier tube 1 can be simplified. .

  Here, since the metal oxide film 53 is formed on the surface of the flange portion 51, when the side tube 2 is heated in a state where the glass flat plate 57 is in close contact with the flange portion 51 as shown in FIG. When the melting point of the glass flat plate 57 is exceeded, the glass flat plate 57 and the metal oxide film 53 diffuse to each other, and a bonding layer (diffusion layer) in which glass and metal are mixed is formed. For this reason, compared with the case where the flange part 51 and the light-receiving surface plate 3 are fused together without forming the metal oxide film 53 on the surface of the flange part 51, the adhesion between the flange part 51 and the light-receiving surface plate 3 is improved. This is advantageous with respect to the sealing performance (vacuum hermeticity) and bonding strength between the flange portion 51 and the light receiving face plate 3.

  Subsequently, a metal oxide film exposed on the surface of the side tube 2 in consideration of later forming a conductive thin film 54 on the inner surface of the side tube 2 or plating the outer surface of the side tube 2. 53 is removed by chemical polishing. When this process is performed, a depression 55 is formed at the boundary between the inner edge surface 51b of the flange portion 51 and the convex portion 3b of the light receiving surface plate 3 as described above.

  Subsequently, a conductive thin film 54 is formed on the inner surface of the side tube 2 and the edge of the lower surface of the light receiving surface plate 3 (the tip surface P of the convex portion 3b). Then, so-called wire bonding is performed in which the conductive thin film 54 formed on the inner surface of the side tube 2 and the conductive thin film 54 formed on the lower surface of the light receiving face plate 3 are connected by a wire 56. Thereby, even if there exists said hollow 55, the electrical connection of the electroconductive thin film 54 formed in the inner surface of the side tube 2 and the electroconductive thin film 54 formed in the lower surface of the light-receiving surface board 3 is ensured. It becomes like this. Then, the photocathode 4 is formed on the inner surface 51 c of the flange portion 51 and the tip surface P of the convex portion 3 b of the light receiving surface plate 3. The photocathode 4 is formed, for example, by depositing antimony over the inner surface of the side tube 2 from the lower surface of the light receiving surface plate 3 (tip surface P of the convex portion 3b), and reacting this with alkali metal deposition.

  Here, as a specific example, a conductive thin film 54 is formed from the entire inner surface of the side tube 2 including the inner surface 51c of the flange portion 51 to the peripheral edge portion of the tip surface P of the convex portion 3b of the light-receiving surface plate 3. The conductive thin film 54 formed on the tip surface P of the portion 3b and the conductive thin film 54 formed on the inner surface 51c of the flange portion 51 were electrically connected by wire bonding. At this time, the conductive thin film 54 is formed with a width of 0.5 mm at the peripheral edge of the front end surface P of the convex portion 3 b, and then the photocathode 4 is formed from the lower surface of the light receiving surface plate 3 to the inner surface 51 c of the flange portion 51. Thus, a photocathode 4 having an effective diameter of 8 mm was obtained.

  As described above, in the present embodiment, since the light receiving face plate 3 is fusion bonded to the flange portion 51 via the metal oxide film 53 formed on the surface of the flange portion 51 of the side tube 2, As described above, the adhesion between the flange portion 51 and the light receiving face plate 3 is sufficiently high. Further, the light receiving face plate 3 is composed of the main body 3 a and the convex 3 b, the main body 3 a is fused to the upper surface 51 a of the flange 51, and the convex 3 b is fused to the inner edge surface 51 b of the flange 51. Therefore, the fusion length between the light receiving face plate 3 and the flange portion 51 can be made sufficiently long. Thereby, the joint strength (fusion strength) and the sealing performance at the fusion interface between the light receiving face plate 3 and the flange portion 51 can be improved.

  A modification of the photomultiplier tube 1 is shown in FIG. The photomultiplier tube 20 shown in FIG. 1 is provided with a metal exhaust pipe 19 at the center of the stem 5. The exhaust pipe 19 can be used to evacuate the inside of the sealed container 8 with a vacuum pump (not shown) or the like after the assembly of the photomultiplier tube 20 is completed. Other configurations are the same as those of the photomultiplier tube 1.

  Another modification of the photomultiplier tube 1 is shown in FIG. The photomultiplier tube 26 shown in the figure is fitted to the ring-shaped side tube 7 fixed to the stem 5 by fitting a side tube 27 longer than the side tube 2 to the lower end of the ring-shaped side tube 7. The formed flange portion 7a and the flange portion 27a formed at the lower end portion of the side tube 27 are fixed by welding. The other configuration is the same as that of the photomultiplier tube 20 shown in FIG.

  FIG. 8 is a configuration diagram showing a radiation detection apparatus including the above-described photomultiplier tube 1 as another embodiment of the photodetector according to the present invention. In the figure, a radiation detection device 21 is provided on the upper side (outside) of the light receiving face plate 3 of the photomultiplier tube 1 and includes a scintillator 22 that converts radiation into light and emits it. Since such a radiation detection apparatus 21 has the photomultiplier tube 1, it is possible to improve the fusion strength and the sealing performance between the light receiving face plate 3 and the flange portion 51 of the side tube 2 as described above. it can.

  The present invention is not limited to the above embodiment. For example, the shape of the flange portion 51 of the side tube 2 is not particularly limited to that of the above embodiment, and can be variously modified as shown in FIG. The flange portion 51 shown in FIG. 9A has an inner edge surface 51b inclined with respect to the upper surface 51a. The flange portion 51 shown in FIG. 9B has inclined surfaces 51d adjacent to the upper surface 51a and the inner edge surface 51b, respectively. The flange portion 51 shown in FIG. 9C has a curved inner edge surface 51b.

  In the above embodiment, the photocathode 4 is formed from the front end surface P of the convex portion 3b of the light receiving face plate 3 to the inner surface 51c of the flange portion 51. However, as shown in FIG. The conductive thin film 54 formed only on the front end surface P of the portion 3 b and formed on the front end surface P of the convex portion 3 b of the light receiving surface plate 3 and the conductive thin film 54 formed on the inner surface 51 c of the flange portion 51 are connected by a wire 56. It is good also as a structure to connect. In this case, the photocathode 4 formed on the peripheral edge of the tip surface P of the convex portion 3b is formed on the surface of the conductive thin film 54.

  In the above embodiment, the light receiving surface plate 3 is fusion bonded to the flange portion 51 of the side tube 2 while forming the light receiving surface plate 3 having the convex portions 3b by using the drop of the glass flat plate 57. Alternatively, the light receiving face plate 3 composed of the main body portion 3a and the convex portion 3b may be made separately, and the light receiving face plate 3 may be fusion bonded to the flange portion 51.

  Moreover, in the said embodiment, although the light-receiving surface plate 3 which consists of the main-body part 3a and the convex part 3b was used, a flat light-receiving surface plate can also be used. In this case, the flat light receiving face plate is fusion bonded to the flange portion 51 via the metal oxide film 53 formed on the outer surface 51a or the inner surface 51c of the flange portion 51.

  Further, in the above-described embodiment, the photodetector is applied to a photomultiplier tube and a radiation detector provided with the photomultiplier tube. However, the photodetector of the present invention is an electron multiplier unit. The present invention can also be applied to an electron tube that does not exist.

It is a top view which shows a photomultiplier tube as one Embodiment of the photodetector which concerns on this invention. It is a bottom view of the photomultiplier shown in FIG. FIG. 3 is a cross-sectional view of the photomultiplier tube shown in FIG. 1 taken along the line III-III. It is an expanded sectional view of the upper part of the photomultiplier shown in FIG. It is a sectional side view which shows the process of melt-bonding to the flange part of a side pipe, forming the light-receiving surface plate shown in FIG. It is a sectional side view which shows the modification of the photomultiplier tube shown in FIG. It is a sectional side view which shows another modification of the photomultiplier tube shown in FIG. It is a block diagram which shows the radiation detection apparatus provided with the photomultiplier tube shown in FIG. 3 as other embodiment of the photodetector which concerns on this invention. It is sectional drawing which shows the modification of the flange part formed in the upper end part of a side pipe. It is an expanded sectional view of the upper part in the modification of the photomultiplier tube shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,20,26 ... Photomultiplier tube (photodetector), 2,27 ... Side tube, 3 ... Light-receiving surface plate, 3a ... Main part, 3b ... Convex part, 4 ... Photoelectric surface, 5 ... Stem, 7 ... Ring 8 ... sealed container, 9 ... electron multiplier, 12 ... anode (anode), 21 ... radiation detector (photodetector), 22 ... scintillator, 51 ... flange, 51a ... upper surface (outer surface), 51b ... inner edge surface, 51c ... inner surface, 53 ... metal oxide film, 54 ... conductive thin film, 56 ... wire, 57 ... glass flat plate.

Claims (6)

A sealed vessel having a conductive side tube and a light receiving face plate joined to one end of the side tube; a photocathode provided in the sealed vessel and converting light incident through the light receiving face plate into electrons; In the photodetector provided in the sealed container and provided with an anode for taking out the electrons emitted from the photocathode as an output signal,
One end of the side tube is provided with a flange portion projecting inside the side tube,
The photodetector, wherein the light receiving face plate is fusion bonded to the flange portion via an oxide film.   The light-receiving face plate is integrated with the main body part fusion-bonded to the outer surface of the flange part via the oxide film, and is integrated with the main body part and enters a space defined by the inner edge surface of the flange part. The photodetector according to claim 1, further comprising: a convex portion formed on the inner edge surface of the flange portion and fusion-bonded via the oxide film.   The said light-receiving surface plate is formed by heating the said side tube in the state which mounted the glass flat plate on the outer surface of the said flange part in which the said oxide film was formed in the surface. Item 3. The photodetector according to Item 2. A conductive thin film is formed on the front end surface of the convex portion and the inner surface of the flange portion,
The conductive thin film formed on the front end surface of the convex portion and the conductive thin film formed on the inner surface of the flange portion are connected by wire bonding,
4. The photodetector according to claim 2, wherein the photocathode is formed so as to cover the conductive thin film at least at a tip surface of the convex portion. 5.   5. The electron multiplier according to claim 1, further comprising: an electron multiplying unit that is provided in the sealed container and multiplies electrons emitted from the photocathode so as to be incident on the anode. Light detector. The photodetector according to claim 1, further comprising a scintillator that is disposed outside the light receiving face plate and converts radiation into light and emits the light.

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