JP5330083B2 - Photomultiplier tube - Google Patents

Description

  The present invention relates to a photomultiplier tube that detects incident light from the outside.

  Conventionally, development of a small photomultiplier tube using a microfabrication technique has been advanced. For example, a planar photomultiplier tube in which a photocathode, a dynode, and an anode are disposed on a translucent insulating substrate is known (see Patent Document 1 below). With such a structure, detection of faint light is realized, and the size of the apparatus is reduced.

US Pat. No. 5,264,693

  However, in the conventional photomultiplier tubes as described above, the structures with different potentials are arranged close to each other on the insulating substrate, so that the withstand voltage between the structures decreases when the structure is downsized. Is a problem. In particular, in the electron multiplying portion, the generated secondary electrons are incident on the insulating substrate, so that the insulating substrate is charged and the withstand voltage between adjacent dynodes may be reduced. In addition, as the size of the dynode is reduced, the physical strength of the dynode decreases. Therefore, the dynode is deformed or damaged due to the connection of the power supply member, and the withstand voltage may also decrease.

  Therefore, the present invention has been made in view of such problems, and an object of the present invention is to provide a photomultiplier tube capable of suppressing a decrease in withstand voltage even when it is downsized.

In order to solve the above problems, a photomultiplier tube according to the present invention includes an envelope including first and second substrates that are arranged to face each other and each facing surface is made of an insulating material, and the first substrate. An electron multiplier having a plurality of stages of dynodes arranged in order and spaced apart from each other along a first direction parallel to the opposing surface from the one end side to the other end side of the opposing surface; The photomultiplier is provided on one end side of the sensor and is separated from the electron multiplier, and converts the incident light from the outside into photoelectrons and emits photoelectrons, and is spaced from the electron multiplier on the other end in the envelope. And an anode part for taking out the electrons multiplied by the electron multiplier as a signal, and a power feeding part for feeding power to the electron multiplier on the opposite surface of the second substrate. The electron multiplying unit is electrically connected to the end on the first substrate side of each of the plurality of dynodes. , A support base which is provided so as to extend over the electron multiplying path formed by the dynodes at multiple stages, the second direction intersecting the first direction along the opposing surfaces of each of the support of the first substrate A power supply member that is formed so as to extend in a direction substantially perpendicular to the opposing surface of the second substrate from one end portion of the both end portions, and that is electrically connected to the power supply portion. A central portion that is joined to the opposing surface and sandwiched between both end portions is configured to be separated from the opposing surface, and the opposing surface at one end portion on the power feeding member side of both end portions Is formed to be larger than the cross-sectional area at the other end of both ends.

  According to such a photomultiplier tube, incident light is converted into photoelectrons by entering the photocathode, and these photoelectrons are formed by a plurality of dynodes on the inner surface of the first substrate in the envelope. The electrons are multiplied by being incident on the electron multiplier, and the multiplied electrons are taken out from the anode as an electric signal. Here, each dynode is provided with a support base at an end portion on the first substrate side, and the support base is directed from one end portion thereof toward the second substrate facing the first substrate. The extending power supply member is electrically connected, and the power supply member is connected to a power supply portion provided on the inner surface of the second substrate, whereby each dynode is supplied with power. Furthermore, both ends of the support base are joined to the opposing surface of the first substrate, the central portion thereof is separated from the opposing surface, and the cross-sectional area along the opposing surface of one end portion on the power feeding member side is The cross-sectional area of the other end is larger. Thereby, since each dynode is separated from the insulating surface of the substrate in the region of the electron multiplying path where the insulating surface of the substrate is likely to withstand the electric charge due to the incidence of secondary electrons or the like, it is possible to suppress a decrease in the withstand voltage. . Furthermore, by increasing the strength of the end of the support base on the part side that contacts the power feeding portion of the substrate, the physical strength of the electron multiplying portion is ensured against pressurization due to contact for power feeding, A decrease in withstand voltage can be suppressed without causing deformation or breakage.

  It is preferable that a concave portion is formed on the opposing surface of the first substrate, and that the central portion of the support base is spaced apart from the opposing surface by being disposed on the concave portion. In this case, since the central part of the support base can be separated from the substrate without reducing the strength of the electron multiplying part, it is possible to further suppress a decrease in withstand voltage.

  It is also preferable that the recess is formed across a plurality of support bases connected to each of a plurality of stages of dynodes. By adopting such a configuration, it is possible to further suppress a decrease in withstand voltage by preventing charging by secondary electrons passing between a plurality of dynodes.

  Furthermore, it is also preferable that the plurality of support bases corresponding to the plurality of dynodes are arranged so that one end and the other end are alternately arranged along the opposing surface of the first substrate. It is. In this way, the cross-sectional area along the substrate at the end of each support base on the power supply member side can be increased, so that the physical strength of the electron multiplier can be further increased, and the withstand voltage can be further increased. The decrease can be suppressed.

  According to the present invention, it is possible to suppress a decrease in withstand voltage even when the size is reduced.

1 is a perspective view of a photomultiplier tube according to a preferred embodiment of the present invention. It is a disassembled perspective view of the photomultiplier tube of FIG. It is a top view of the side wall frame of FIG. It is a partially broken perspective view which shows the principal part of the side wall frame and lower frame of FIG. It is sectional drawing along the VV line of the photomultiplier tube of FIG. (A) is the bottom view which looked at the upper side frame of FIG. 1 from the back surface side, (b) is the top view of the side wall frame of FIG. It is a perspective view which shows the connection state of the upper side frame of FIG. 6, and a side wall frame. It is a partially broken perspective view of the side wall frame and lower frame of FIG. It is a top view of the electron multiplication part which concerns on the comparative example of this invention. It is a top view of the electron multiplication part which concerns on another comparative example of this invention. It is a perspective view of the lower frame concerning the modification of the present invention. It is the bottom view which looked at the lower frame of Drawing 11 from the back side. It is a perspective view of the lower frame concerning another modification of the present invention.

  Hereinafter, preferred embodiments of a photomultiplier according to the present invention will be described in detail with reference to the drawings. In the description of the drawings, the same or corresponding parts are denoted by the same reference numerals, and redundant description is omitted.

    FIG. 1 is a perspective view of a photomultiplier tube 1 according to a preferred embodiment of the present invention, and FIG. 2 is an exploded perspective view of the photomultiplier tube 1 of FIG.

  A photomultiplier tube 1 shown in FIG. 1 is a photomultiplier tube having a transmission type photocathode, and is an upper frame (second substrate) 2, a side wall frame 3, and a side wall frame with respect to the upper frame 2. 3 is provided with a casing 5 which is an envelope composed of a lower frame (first substrate) 4 facing each other with 3 interposed therebetween. In this photomultiplier tube 1, the light incident direction on the photocathode intersects the electron multiplying direction in the electron multiplying portion, that is, light is incident from the direction indicated by arrow A in FIG. 1. The photoelectrons emitted from the photocathode are incident on the electron multiplier, cascade-amplify secondary electrons in the direction indicated by arrow B, and take out a signal from the anode.

  In the following description, along the electron multiplication direction, the upstream side (photocathode side) of the electron multiplication path (electron multiplication channel) is referred to as “one end side” and the downstream side (anode side) is referred to as “ The other end side. Subsequently, each component of the photomultiplier tube 1 will be described in detail.

  As shown in FIG. 2, the upper frame 2 is configured with a wiring board 20 whose main material is a rectangular flat plate-like insulating ceramic as a base material. As such a wiring board, a multilayer wiring board such as LTCC (Low Temperature Co-fired Ceramics) capable of designing a fine wiring and freely designing the front and back wiring patterns is used. On the main surface 20b, the wiring substrate 20 is electrically connected to the side wall frame 3, a photocathode 41 (to be described later), a focusing electrode 31, a wall electrode 32, an electron multiplying portion 33, and an anode portion 34 to be externally connected. A plurality of conductive terminals 201 </ b> A to 201 </ b> D for supplying power from and extracting signals are provided. The conductive terminal 201A is used for supplying power to the side wall frame 3, the conductive terminal 201B is used for supplying power to the photocathode 41, the focusing electrode 31, and the wall electrode 32. The conductive terminal 201C is supplied to the electron multiplier 33. For this purpose, the conductive terminal 201D is provided for feeding power and extracting signals from the anode section 34, respectively. These conductive terminals 201 </ b> A to 201 </ b> D are mutually connected to a conductive film and conductive terminals (details will be described later) on the insulating facing surface 20 a facing the main surface 20 b inside the wiring board 20. These conductive films, conductive terminals and side wall frame 3, photocathode 41, focusing electrode 31, wall electrode 32, electron multiplier 33, and anode 34 are connected. The upper frame 2 is not limited to the multilayer wiring board provided with the conductive terminals 201, and is made of an insulating material such as a glass substrate through which conductive terminals for supplying power from outside and taking out signals are provided. A plate-like member may be used.

  The side wall frame 3 is configured by using a rectangular flat silicon substrate 30 as a base material. A penetrating portion 301 surrounded by a frame-like side wall portion 302 is formed from the main surface 30a of the silicon substrate 30 toward the surface 30b facing the main surface 30a. The through portion 301 has a rectangular opening, and the outer periphery thereof is formed along the outer periphery of the silicon substrate 30.

  In this penetration part 301, the wall-shaped electrode 32, the focusing electrode 31, the electron multiplication part 33, and the anode part 34 are arrange | positioned toward the other end side from one end side. The wall electrode 32, the focusing electrode 31, the electron multiplying portion 33, and the anode portion 34 are formed by processing the silicon substrate 30 by RIE (Reactive Ion Etching) processing or the like, and uses silicon as a main material.

  The wall-like electrode 32 is a frame-like electrode formed so as to surround a photocathode 41 (to be described later) when viewed from a direction facing a facing surface 40a of the glass substrate 40 to be described later (substantially perpendicular to the facing surface 40a). . The focusing electrode 31 is an electrode for converging photoelectrons emitted from the photocathode 41 and guiding the photoelectrons to the electron multiplier 33, and is provided between the photocathode 41 and the electron multiplier 33. .

  The electron multiplier section 33 has N stages (N is set to different potentials) along the electron multiplication direction from the photocathode 41 toward the anode section 34 (the direction indicated by the arrow B in FIG. 1, the same applies hereinafter). It is composed of two or more integers) dynodes (electron multipliers), and has a plurality of electron multiplier paths (electron multiplier channels) across each stage. Further, the anode part 34 is arranged at a position sandwiching the electron multiplying part 33 together with the photocathode 41.

  The wall electrode 32, the focusing electrode 31, the electron multiplying portion 33, and the anode portion 34 are respectively provided with an anodic bonding, a diffusion bonding, and a sealing material such as a low melting point metal (for example, indium) on the lower frame 4. It is fixed by the joining etc. which were used, and is arrange | positioned two-dimensionally on this lower frame 4 by this.

  The lower frame 4 is configured with a rectangular flat glass substrate 40 as a base material. The glass substrate 40 is opposed to the facing surface 20 a of the wiring substrate 20 by glass that is an insulating material, and forms a facing surface 40 a that is the inner surface of the housing 5. On the facing surface 40a, a portion facing the penetrating portion 301 of the side wall frame 3 (a portion other than the joining region with the side wall portion 302) is located at the end opposite to the anode portion 34 side at the transmission type photocathode. The photocathode 41 is formed. In addition, a rectangular depression (recess) 42 for preventing the multiplication electrons from entering the facing surface 40a is formed at a portion where the electron multiplying portion 33 and the anode portion 34 are mounted on the facing surface 40a. Has been.

  The internal structure of the photomultiplier tube 1 will be described in detail with reference to FIGS. 3 is a plan view of the side wall frame 3 of FIG. 1, FIG. 4 is a partially broken perspective view showing the main parts of the side wall frame 3 and the lower frame 4 of FIG. 1, and FIG. 5 is the photomultiplier of FIG. It is sectional drawing along the VV line of the pipe | tube.

  As shown in FIG. 3, the electron multiplier 33 in the penetrating part 301 is directed from one end side to the other end side on the facing surface 40a (toward the direction indicated by the arrow B which is the electron multiplying direction) It is composed of a plurality of dynodes 33a to 33l that are spaced apart in order. These multiple stages of dynodes 33a to 33l continue along the direction indicated by arrow B from the first stage dynode 33a on one end side to the last stage (Nth stage) dynode 33l on the other end side. A plurality of electron multiplying channels C composed of N electron multiplying holes provided in the plurality are formed in parallel.

  The photocathode 41 is spaced from the first dynode 33a on the one end side on one end side on the facing surface 40a with the focusing electrode 31 in between. The photocathode 41 is formed as a rectangular transmissive photocathode on the facing surface 40 a of the glass substrate 40. When incident light transmitted through the glass substrate 40 which is the lower frame 4 from the outside reaches the photocathode 41, photoelectrons corresponding to the incident light are emitted, and the photoelectrons are first-staged by the wall electrode 32 and the focusing electrode 31. Guided to eye dynode 33a.

  Further, the anode part 34 is provided away from the final stage dynode 33l on the other end side on the other end side on the facing surface 40a. This anode part 34 is an electrode for taking out the electrons which have been multiplied in the direction indicated by the arrow B in the electron multiplication channel C by the electron multiplication part 33 as an electric signal.

As shown in FIG. 4, the dynodes 33 a to 33 d in a plurality of stages are arranged apart from the bottom of the recess 42 formed on the facing surface 40 a of the lower frame 4. The dynodes 33a are arranged in a direction substantially perpendicular to the electron multiplying direction along the facing surface 40a, and extend to the facing surface 20a of the upper frame 2 and have a plurality of columnar portions 51a and a plurality of columnar portions. 51a includes a base (support) 52a that is continuously formed at the end of the recess 42 on the side of the recess 42 and extends in a direction substantially perpendicular to the electron multiplication direction along the bottom of the recess 42. The dynodes 33b to 33d also have the same structure as the dynode 33a with respect to the plurality of columnar portions 51b to 51d and the base portions 52b to 52d. An electron multiplying channel C is formed between adjacent members in each of the columnar portions 51a to 51d, and the base portions 52a to 52d extend across the region A _C (FIG. 3) where the electron multiplying channel C is formed. Is provided. Here, the base portions 52 a to 52 d serve to electrically connect the plurality of columnar portions 51 a to 51 d to each other and hold the plurality of columnar portions 51 a to 51 d apart from the bottom of the recess 42. Have. In the present embodiment, in the dynodes 33a to 33d, the plurality of columnar portions 51a to 51d and the base portions 52a to 52d are integrally formed, but the columnar portion and the base portion are separated. Also good. Although not shown, the dynodes 33e to 33l have the same structure.

  Further, at one end portion of the base portions 52b and 52d in the direction perpendicular to the electron multiplication direction, a power feeding portion 53b having a substantially cylindrical shape extending from the end portion toward the upper frame 2 substantially vertically. , 53d are integrally formed. The power feeding parts 53b and 53d are members for feeding power to the plurality of columnar parts 51b and 51d via the base parts 52b and 52d.

  As shown in FIG. 5, the dynode 33b having the structure as described above is perpendicular to the electron multiplication direction, and both ends of the base portion 52b in the direction along the opposing surface 40a are opposed to the opposing surface 40a. The central portion 54b fixed to the lower frame 4 by being joined to the lower frame 4 and sandwiched between both ends of the base portion 52b is such that the surface on the opposite surface 40a side is separated from the bottom portion of the recessed portion 42. Placed in. In other words, in the dynode 33b, the electron multiplication region in which the electron multiplication channel C is formed is disposed away from the lower frame 4, is perpendicular to the electron multiplication direction, and is along the facing surface 40a. A recess 42 is formed in the facing surface 40a of the lower frame 4 so that both ends in the direction are fixed to the lower frame 4. Although there are small differences in shape, the other dynodes 33a, 33c to 33l have the same basic structure with respect to the columnar portion, the base portion, and the power feeding portion. Correspondingly, the recess 42 on the facing surface 40a is formed with a width that straddles the base portion and the anode portion 34 of the plurality of dynodes 33a to 33l in the electron multiplication direction. That is, the recessed portion 42 has a bottom surface that is recessed integrally including not only the portions corresponding to the dynodes 33a to 33l and the anode portion 34, but also the region sandwiched between them, in the first stage dynode 33a. The region from the electron multiplying region where the electron multiplying channel C is formed to the region facing the electron multiplying region of the final stage dynode 33l in the anode part 34 is continuously formed so as to be separated from the lower frame 4. Yes.

  Next, the wiring structure of the photomultiplier tube 1 will be described with reference to FIGS. 6A is a bottom view of the upper frame 2 viewed from the back surface 20a side, FIG. 6B is a plan view of the side wall frame 3, and FIG. 7 is a connection between the upper frame 2 and the side wall frame 3. It is a perspective view which shows a state.

  As shown in FIG. 6A, a plurality of conductive films (feeding portions) electrically connected to the conductive surfaces 201B, 201C, and 201D inside the upper frame 2 are provided on the facing surface 20a of the upper frame 2, respectively. 202) and the conductive terminal 203 electrically connected to the conductive terminal 201A inside the upper frame 2 are provided. As shown in FIG. 6B, the electron multiplier 33 is provided with power supply portions 53a to 53l for connection with the conductive film 202, as described above. At the end, a power feeding unit 37 for connection with the conductive film 202 is provided upright. Further, at the corner of the wall electrode 32, a power feeding unit 38 for connection with the conductive film 202 is provided upright. Further, the focusing electrode 31 is electrically connected to the wall electrode 32 by being integrally formed on the wall electrode 32 and the lower frame 4 side. Further, a rectangular flat plate-like connecting portion 39 is integrally formed on the wall-like electrode 32 on the facing surface 40a side of the lower frame 4, and the connecting portion 39 and the photocathode 41 on the facing surface 40a. The wall electrode 32 and the photocathode 41 are electrically connected to each other by bonding a conductive film (not shown) formed in electrical contact.

  When the upper frame 2 and the side wall frame 3 configured as described above are joined, the conductive terminal 203 is electrically connected to the side wall portion 302 of the side wall frame 3. In addition, the power feeding parts 53a to 53l of the electron multiplying part 33, the power feeding part 37 of the anode part 34, and the power feeding part 38 of the wall-shaped electrode 32 correspond to each other through a conductive member made of gold (Au) or the like. The conductive film 202 is independently connected. With such a connection configuration, the side wall portion 302, the electron multiplying portion 33, and the anode portion 34 are electrically connected to the conductive terminals 201A, 201C, and 201D, respectively, so that power can be supplied from the outside, and the wall shape The electrode 32, together with the focusing electrode 31 and the photocathode 41, is electrically connected to the conductive terminal 201B and supplied with power from the outside (FIG. 7).

Here, as shown in FIG. 6 (b), the sectional area S ₁ along the opposing surface 40a of the one end connected to the feeding portion 53b of the both ends of the base portion 52b of the dynode 33b, the opposite ends to be larger than the cross-sectional area S ₂ which corresponds to the joint portion between the opposing surfaces at the other end of the section, the shape of the base portion 52b and the feeding part 53b of the dynode 33b is defined. In this dynode 33b, the size relationship between one end where the power feeding portion 53b is provided and the other end is continuously satisfied until the entire end of the dynode 33b, that is, the surface on the upper frame 2 side is reached. ing. Therefore, also in the area when viewed from the direction facing directly from the facing surface 40a and the volume thereof, one end provided with the power feeding portion 53b is larger than the other end. As described above, since one end portion provided with the power feeding portion 53b is superior in physical strength and has a larger surface on the upper frame 2 side, a conductive member made of gold (Au) or the like. It is also effective for reliable electrical connection. The other dynodes 33a and 33c to 33l constituting the electron multiplying unit 33 are also defined to have a cross-sectional shape that satisfies the same relationship. Further, in the plurality of dynodes 33a to 33l, one end portion on the power feeding portions 53a to 53l side and the other end portion on the opposite side are alternately arranged along the electron multiplication direction on the facing surface 40a. Are arranged as follows. In other words, the dynodes 33a to 33l of the plurality of stages are oriented in the direction of the base portion with respect to the arrangement direction of the power feeding portions 53a to 53l (direction extending from one end portion where the power feeding portion is provided to the other end portion). The orientation of the base portion defined in (1) is alternately arranged on the facing surface 40a so as to be opposite to each other.

  According to the photomultiplier tube 1 described above, incident light is converted into photoelectrons by entering the photocathode 41, and the photoelectrons are converted into a plurality of dynodes on the inner surface 40 a of the lower frame 4 in the housing 5. The electrons are multiplied by sequentially entering the electron multiplication channel C formed by 33a to 33l, and the multiplied electrons are taken out from the anode part 34 as an electric signal.

Here, if the dynodes 33a to 33d are described as an example, each of the dynodes 33a to 33d is provided with base portions 52a to 52d at end portions on the lower frame 4 side, and the base portions 52a to 52d are provided with the base portions 52a to 52d. Are electrically connected to power supply portions 53a to 53d extending from one end portion thereof toward the upper frame 2 facing the lower frame 4, and the power supply portions 53a to 53d are provided on the inner surface 20a of the upper frame 2. By being connected to the film 202, the dynodes 33a to 33d are supplied with power. Further, the base portions 52a to 52d are joined at opposite ends to the facing surface 40a of the lower frame 4, and the central portion is separated from the facing surface 40a, and one end portion on the power feeding portions 53a to 53d side. sectional area S ₁ along the opposing surface 40a of are larger than the cross-sectional area S ₂ of the other end. Thereby, since each dynode 33a-33d is spaced apart from the insulating surface of the lower frame 4 in the region of the electron multiplication path where the insulating surface of the lower frame 4 is easily charged by the incidence of secondary electrons or photoelectrons, A decrease in withstand voltage can be suppressed. At the same time, by increasing the strength of the end portions of the base portions 52a to 52d that are in contact with the conductive film 202 of the upper frame 2, the physicality of the electron multiplying portion 33 with respect to pressurization due to contact for power feeding is increased. Since a sufficient strength can be ensured, a decrease in withstand voltage can be suppressed without causing deformation or breakage.

  In addition, a recess 42 is formed on the facing surface 40 a of the lower frame 4, and the central portions of the base portions 52 a to 52 d are disposed on the recess 42. The central part of the base parts 52a to 52d can be separated from the insulating surface of the lower frame 4 without reducing the strength. Furthermore, since the hollow part 42 is formed ranging over the center part of the several base parts 52a-52d, it is charged by the incident to the insulating surface of the secondary electron which passes between the multistage dynodes 33a-33d. By preventing this, it is possible to further suppress a decrease in withstand voltage.

  The dynodes 33a to 33l are separated from the facing surface 40a of the lower frame 4 to provide the following effects. That is, for example, in the case of the dynodes 33a and 33b, when the secondary electron surface on the surface of the columnar portions 51a and 51b is active, between the dynodes 33a and 33b and at the lower part of the dynodes 33a and 33b (directions indicated by arrows in FIG. ), The flow of alkali metal (K, Cs, etc.) vapor is improved, and it is easy to form a uniform secondary electron surface. In addition, since the bonding area between the electron multiplier 33 and the lower frame 4 can be reduced, it is possible to prevent a bonding failure caused by foreign matter being caught between the electron multiplier 33 and the lower frame 4. Reliability can be increased. Furthermore, since the internal volume of the housing 5 can be increased by the structure in which the recess 42 is provided to separate the dynodes 33a to 331, the degree of vacuum is reduced even if gas is released from the internal components. Can be suppressed. For example, the thickness of the dynodes 33a to 33l is 1 mm and the thickness of the dynodes 33a to 33l is equal to that of the photomultiplier tube without the recess 42, the depth of the recess 42 is 0.2 mm, and the recess 42 The photomultiplier tube in which the ratio of the processing area to the facing surface 40a is 50% can increase the internal volume by about 10%. Furthermore, even if there is a foreign substance in the housing 5, the foreign substance is likely to fall into the recess 42 that is separated from the dynodes 33a to 33l, so that the foreign substance is not easily caught between the dynodes 33a to 33l. , And withstand voltage failure due to foreign matter is reduced. In addition, since the contact area between the housing 5 and the dynodes 33a to 33l becomes small, the influence of the temperature change in the housing 5 does not easily reach the electron multiplying unit 33, and the secondary electron surface due to the increase in the ambient temperature. Damage can be reduced. In particular, this effect is important in a structure in which an electrode such as an electron multiplier is disposed directly on the inner surface of the housing 5.

  Further, the plurality of base portions corresponding to the plurality of dynodes 33a to 33l have one end on the power feeding portions 53a to 53l side and the other end on the opposite side along the facing surface 40a of the lower frame 4. They are staggered. That is, for example, in the adjacent dynode 33b and dynode 33c, the end of the dynode 33c facing one end of the dynode 33b on the power feeding unit 53b side is the other end, and the dynode 33c facing the other end of the dynode 33b. Are arranged so as to be one end on the power feeding portion 53c side. And it arrange | positions so that this relationship may be satisfy | filled over the multistage dynodes 33a-331. That is, since the one end on the power feeding units 53a to 53l side is the other end of the adjacent dynodes, the lower side of the end on the power feeding unit 53a to 53l side of each base unit Since the cross-sectional area along the frame 4 can be increased, the physical strength of the electron multiplier 33 can be further increased. Further, the other end of each of the plurality of stages of dynodes 33b to 33l is a columnar portion extending substantially vertically toward the upper frame 2, and is viewed from the direction facing the facing surface 40a of the lower frame 4, The most advanced part is recessed in the recessed part 42 side rather than the electric power feeding parts 53a-53l. Therefore, the space | interval of the other edge part and electric power feeding part 53a-53l becomes large. Furthermore, the cross-sectional shape along the lower frame 4 at the other end (the shape viewed from the direction facing the facing surface 40a of the lower frame 4) is a direction substantially perpendicular to the electron multiplication direction (each dynode). In the direction from the one end to the other end). By having a pointed shape in this way, the junction area to the lower frame 4 can be increased while maintaining a distance from the power feeding portions 53a to 53l, and a decrease in withstand voltage can be suppressed. On the other hand, as shown in FIG. 9, in the case where the end portions on the power feeding portions 53a to 53l side are arranged adjacent to each other along the facing surface 40a, the withstand voltage between the power feeding portions 53a to 53l is considered. Then, it is necessary to set a large interval between dynodes (for example, 0.5 mm when the thickness of the dynode is 0.35 mm). As a result, when the same number of dynodes are arranged, a large area is required, and when a silicon substrate is processed by batch processing, the area per chip is increased, thereby increasing the chip cost. Also become. In addition, an increase in the dynode interval causes a decrease in the electron multiplication factor, thereby reducing the performance as a photomultiplier tube. On the other hand, in order to narrow the dynode interval, as shown in FIG. 10, it is also possible to arrange the power feeding portions 53a to 53f of the dynodes 33a to 33f alternately and adjacently so as to meander along the facing surface 40a. It is done. As a result, the dynode interval is narrowed (for example, 0.2 mm), and the electron multiplication factor can be increased to some extent. It is necessary to make the portion between the end portions on the power feeding portions 53b and 53d side and the central portion of the dynodes 33b and 33d extremely narrow (for example, 0.05 mm). As a result, the strength of the dynodes 33b and 33d may be reduced to cause cracks and breakage, which may make it impossible to supply power to the secondary electron surface. Alternatively, it is conceivable that even if no crack is generated, the electric resistance value is increased, and the potential supply from the power feeding parts 53b and 53d to the central part of the dynode having the secondary electron surface is hindered. From this, it can be seen that the arrangement of the dynodes 33a to 33l in the present embodiment is advantageous from the aspect of electron multiplication factor because it suppresses a decrease in withstand voltage and enables an arrangement with a narrow dynode interval. It was.

  In addition, this invention is not limited to embodiment mentioned above. For example, as shown in FIGS. 11 and 12, on the bottom surface of the recess 42 of the lower frame 4, between the dynodes 33a to 33l of the electron multiplier 33 and between the electron multipliers 33 (dynode 33l). A plurality of strip-shaped conductive films 43 may be formed so as to prevent the insulating surface of the lower frame 4 from being exposed corresponding to the position between the anode portion 34 and the anode portion 34. The conductive film 43 is supplied with power by a conductive terminal 44 provided so as to penetrate the lower frame 4. As a result, it is possible to reliably prevent withstand electricity due to incidence of electrons passing through the electron multiplier 33 on the lower frame 4. Further, as shown in FIG. 13, the lower frame 4 can be prevented from being charged by providing a conductive film 45 on the bottom surface of the recess 42 across the entire electron multiplier 33. However, in this case, the potential difference between the conductive film 45 and each dynode of the electron multiplier section 33 becomes large, so the configuration of FIG. 11 is more preferable.

  In the present embodiment, the photocathode 41 is a transmissive photocathode, but may be a reflective photocathode, or the photocathode 41 may be disposed on the upper frame 2 side. When the photocathode 41 is disposed on the upper frame 2 side, the upper frame 2 can be a glass substrate or other insulating substrate having a light transmission property embedded with a power supply terminal. Various insulating substrates can be used in addition to the glass substrate. Further, the anode part 34 may be disposed between the dynode 33k and the dynode 33l.

DESCRIPTION OF SYMBOLS 1 ... Photomultiplier tube, 2 ... Upper frame (2nd board | substrate), 4 ... Lower frame (1st board | substrate), 5 ... Case (envelope), 20a, 40a ... Opposite surface, 33 ... Electron Multiplier, 33a to 33l ... Dynode, 51a to 51d ... Columnar, 52a to 52d ... Base (support), 53a to 53l ... Feeder (feeder), 54b ... Center, 34 ... Anode, 41 ... photocathode, 42 ... recess (concave portion), 202 ... conductive film (feeding unit), _{S 1,} S 2 _... cross-sectional area.

Claims (4)

An envelope including first and second substrates that are disposed opposite to each other and each facing surface is made of an insulating material;
Electron multiplication having a plurality of stages of dynodes arranged in sequence along a first direction parallel to the opposing surface from one end side to the other end side of the opposing surface of the first substrate. And
A photoelectric surface provided on the one end side in the envelope apart from the electron multiplier, converting incident light from the outside into photoelectrons, and emitting the photoelectrons;
An anode part provided at a distance from the electron multiplier on the other end side in the envelope, and taking out electrons multiplied by the electron multiplier as a signal;
On the facing surface of the second substrate, a power feeding unit for feeding power to the electron multiplying unit is provided,
The electron multiplier is
A support base electrically connected to the first substrate side end of each of the plurality of dynodes and provided to straddle an electron multiplier formed by the plurality of dynodes;
From one end of both end portions in the second direction intersecting the first direction along the facing surface of the first substrate of each of the support bases , substantially perpendicular to the facing surface of the second substrate. A power supply member that is formed to extend in any direction and is electrically connected to the power supply unit;
Have
The support base is
The both end portions are joined to the facing surface, and a central portion sandwiched between the both end portions is configured to be separated from the facing surface,
The cross-sectional area along the facing surface at one end portion on the power feeding member side of the both end portions is formed to be larger than the cross-sectional area at the other end portion of the both end portions.
A photomultiplier tube characterized by that. A recess is formed on the facing surface of the first substrate,
The central portion of the support base is spaced from the facing surface by being disposed on the concave portion.
The photomultiplier tube according to claim 1. The recess is formed across a plurality of support bases connected to each of the plurality of dynodes.
3. The photomultiplier tube according to claim 2, wherein The plurality of support bases corresponding to the plurality of stages of dynodes are arranged such that the one end and the other end are alternately arranged along the facing surface of the first substrate. ,
The photomultiplier tube according to any one of claims 1 to 3, wherein:

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