JP2006127982A - Photomultiplier tube and radiation detection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photomultiplier tube in which noise mixing into an electric signal taken out from an anode pin is sufficiently prevented, and to provide a radioactive ray detecting device equipped with it. <P>SOLUTION: A stem 35 surrounded by a conductive side tube 7 is made to be as an insulating base material 36, the inside brim part in the vicinity of the anode pin 13 of the base material 36 is made to have a chamfered shape 36d, while a creepage distance Y1 along the base material 36 (insulating body) between the insulating side tube 7 and the triple junction X1 which is a point where the conductive anode pin 13, the insulating base material 36 joined with the anode pin 13, and vacuum intersect with each other is made to be sufficiently long compared with the case in which there is no chamfered shape 15c. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a photomultiplier tube using a photoelectric effect and a radiation detection apparatus using the same.

  As a photomultiplier tube, a light-receiving face plate is provided at one end of a cylindrical side tube and a stem is provided at the other end to form a vacuum-sealed container. A photocathode is provided on the inner face of the light-receiving face plate. The electron multiplier having a plurality of stages of dynodes and an anode are stacked opposite to the photocathode, and a plurality of stem pins respectively connected to the dynodes and anodes of each stage are disposed in a sealed container. The incident light incident through the light-receiving face plate is converted into electrons on the photocathode, and the electrons emitted from the photocathode are passed through each stem pin. The so-called head-on type, in which the electrons are sequentially multiplied by an electron multiplier having each dynode to which a voltage of 1 is applied, and the multiplied electrons reaching the anode are taken out through an anode pin which is one of the stem pins as an electrical signal. Photomultiplier tube It is known.

In such a photomultiplier tube, in order to reduce the number of parts, the metal stem is made of tapered hermetic glass, and noise is prevented when the side tube is made of glass. A photomultiplier tube in which the side tube is made of metal is disclosed (for example, see Patent Document 1).
JP-A-5-290793 (FIG. 7)

  However, in such a photomultiplier tube, it is desired to further reduce noise contamination with respect to the electric signal taken out from the anode pin.

  The present invention has been made to solve the above-described problems, and provides a photomultiplier tube and a radiation detection apparatus including the photomultiplier tube that can sufficiently prevent noise from being mixed into an electric signal taken out from an anode pin. The purpose is to do.

  A photomultiplier tube according to the present invention is provided in a sealed container in a vacuum state, and a photocathode that converts incident light that has entered through a light-receiving face plate constituting one end of the sealed container into electrons, An electron multiplier provided inside the container for multiplying electrons emitted from the photocathode, an anode for taking out the electrons multiplied by the electron multiplier as an output signal, and an end on the other side of the sealed container In a photomultiplier tube comprising: a stem that constitutes a portion; and a plurality of stem pins that are inserted into the stem and led out from the inside of the sealed container and electrically connected to the anode and the electron multiplier An insulating base material is provided that includes a conductive side tube that forms a container and surrounds the stem from its side, and the stem includes an anode pin that is electrically connected to the anode and is joined by penetrating the stem pin. Have Inner end of the anode pin vicinity of scan material, is characterized in that there is a chamfered shape.

  According to such a photomultiplier tube, the stem surrounded by the conductive side tube is an insulating base material, and the inner edge of the base material near the anode pin is chamfered. Therefore, the creeping distance along the base material (insulator) between the conductive anode pin, the insulating base material joined to the anode pin, the triple junction where the vacuum intersects and the conductive side tube, The length is made sufficiently longer than when there is no chamfered shape. As a result, it is possible to sufficiently prevent noise from being mixed into the electrical signal extracted from the anode pin.

  Here, in the case where the stem has a two-layer structure while exhibiting the same action as described above, specifically, the stem is attached to the base material and either the inner surface or the outer surface of the base material. And a presser material through which a stem pin that is bonded to the base material is passed, and when the presser material is bonded to the inner surface of the base material, the presser material has an insulating property. In addition, there is a configuration in which the chamfered shape is provided at the inner edge portion in the vicinity of the anode pin in the presser material.

  In addition, when the stem has a structure of three or more layers while exhibiting the above-described action in a similar manner, specifically, the stem is bonded to both the base material and both the inner surface and the outer surface of the base material. In addition, a member having at least three layers including a presser material through which the stem pin joined to the base material is passed, and the member through which the anode pin is passed by the member inside the base material has an insulating property and has a chamfered shape. The structure provided in the edge part inside the anode pin vicinity of the member which lets an anode pin pass by the member inside the said base material is mentioned.

  Here, if a scintillator that converts the radiation into light and emits it is disposed outside the light receiving face plate of the photomultiplier tube, a suitable radiation detection device that exhibits the above-described action can be obtained.

  According to such a photomultiplier tube and a radiation detection apparatus, it is possible to sufficiently prevent noise from being mixed into an electrical signal extracted from the anode pin.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of a photomultiplier tube and a radiation detection apparatus according to the 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.

[First Embodiment]
1 and 2 are a plan view and a bottom view showing an embodiment of a photomultiplier tube 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.

  As shown in FIGS. 1 to 3, the photomultiplier tube 1 has a metal side tube 2 having a substantially cylindrical shape. As shown in FIG. 3, a glass light receiving face plate 3 is airtightly fixed to the upper (one side) opening end of the side tube 2, and light incident through the light receiving face plate 3 is incident on the inner surface of the light receiving face plate 3. A photocathode 4 for conversion to electrons is formed. Further, as shown in FIGS. 2 and 3, a disc-shaped stem 5 is disposed at the opening end on the lower side (other side) of the side tube 2. 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, and the stem 5 is surrounded from the side. Thus, the metal ring-shaped side tube 7 is fixed in an airtight manner. Then, as shown in FIG. 3, the flange portion 2a formed at the lower end portion of the upper side tube 2 and the flange portion 7a having the same diameter formed at the upper end portion of the lower ring-shaped side tube 7 are welded. The side tube 2 and the ring-shaped side tube 7 are fixed in an airtight manner to form a sealed container 8 whose inside is kept in a vacuum state.

  In the sealed container 8 formed in this way, 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. . As shown in FIGS. 1 and 3, dynode connection pieces 10c projecting outward are formed at predetermined edges of each dynode 10, and are inserted into the stem 5 on the lower surface side of each dynode connection piece 10c. The tip portion of the predetermined stem pin 6 is fixed by welding. Thereby, each dynode 10 and each stem pin 6 are electrically connected.

  Further, as shown in FIG. 3, in the sealed container 8, electrons emitted from the photocathode 4 are converged and guided to the electron multiplier 9 between the electron multiplier 9 and the photocathode 4. The flat focusing electrode 11 is installed, and the electron that is multiplied by the electron multiplier 9 and emitted from the final stage dynode 10b is taken out as an output signal in a stage above the final stage dynode 10b. A plate-like anode (anode) 12 is laminated. As shown in FIG. 1, projecting pieces 11a projecting outward are formed at the four corners of the focusing electrode 11, and a predetermined stem pin 6 is welded and fixed to each projecting piece 11a. The electrical connection is 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. Electrical connection with the anode 12 is made. When a predetermined voltage is applied to the electron multiplier 9 and the anode 12 by the stem pin 6 connected to a power supply circuit (not shown), the photocathode 4 and the focusing electrode 11 are set to the same potential, and each dynode 10 is laminated. The potential is set to become higher as the level goes from the upper level to the lower level. The anode 12 is set to a higher potential than the final dynode 10b. In the present embodiment, the final stage dynode 10b is directly mounted on and fixed to the upper surface of the stem 5. For example, the final stage dynode 10b is supported by a support member installed on the upper surface of the stem 5. However, a configuration may be adopted in which a space is interposed between the dynode 10b at the final stage and the upper surface of the stem 5.

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 connected to the anode 12.

  Next, the configuration of the stem 5 described above will be described in more detail. 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).

  As shown in FIG. 3, 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 joined to the lower side (outer side) of the base material 14. The ring-shaped side tube 7 is fixed to the side surface of the three-layer structure of the material 16. In the present embodiment, the stem 5 is fixed to the ring-shaped side tube 7 by joining the side surface of the base material 14 constituting the stem 5 and the inner wall surface of the ring-shaped side tube 7. Here, the lower (outer) surface of the lower pressing member 16 protrudes below the lower end of the ring-shaped side tube 7, but the fixing position of the stem 5 with respect to the ring-shaped side tube 7 is in the above form. It is not limited.

  The base material 14 is a disk-shaped member made of insulating glass whose main component is, for example, Kovar and has a melting point of about 780 degrees, and does not transmit light from the lower surface side into the sealed container 8. It is black. As shown in FIG. 4, a plurality (15) of openings 14 a having substantially the same diameter as the outer diameter of the stem pin 6 are formed in the base material 14 along the outer periphery of the base material 14.

  The upper presser material 15 is a disk-shaped member made of insulating glass having a melting point of about 1100 degrees and a higher melting point than the base material 14 by adding, for example, alumina powder to Kovar. It is black to effectively absorb the light emission in the container 8. As shown in FIG. 5, a plurality (15) of openings 15 a arranged in the same manner as the base material 14 are formed in the upper presser material 15. Each opening 15a has a larger diameter than the opening 14a formed in the base member 14, and at least two or more predetermined portions of the opening 15a allow a positioning jig (described later) 18 to enter the base member 14. In order to make it possible, the large-diameter opening 15b has a larger diameter than the other openings 15a. In the upper presser member 15, the large-diameter openings 15 b are arranged with a phase angle of 90 degrees at three positions excluding the opening 15 a through which the anode pin 13 is inserted. Further, the upper pressing member 15 has a chamfered shape 15c at the edge near the opening 15a through which the anode pin 13 is inserted.

  Similarly to the upper presser material 15, the lower presser material 16 is a circle made of insulating glass having a melting point of about 1100 degrees and a higher melting point than the base material 14 by adding, for example, alumina powder to Kovar. It is a plate-like member, has a white color due to the difference in the composition of the alumina-based powder to be added, and has higher physical strength than the base material 14 and the upper presser material 15. As shown in FIG. 6, the lower pressing member 16 is also formed with openings 16 a similar to the upper pressing member 15, and at least two predetermined positions of the opening 16 a enter the positioning jig 18. The large-diameter opening 16b is set to enable the above. In the lower presser member 16, the large-diameter opening 16 b is disposed at four positions including the opening 16 a through which the anode pin 13 is inserted with a phase angle of 90 degrees, and three places other than the large-diameter opening 16 b through which the anode pin 13 is inserted. The large diameter opening 16 b is disposed coaxially with the large diameter opening 15 b of the upper presser member 15. Furthermore, a circular base material leaching opening 16 c is formed in the central portion of the lower presser material 16.

  As shown in FIG. 3, the base material 14, the upper presser material 15, and the lower presser material 16 are aligned with the axial positions of the openings 14a, 15a, 16a and the large diameter openings 15b, 16b. The base material 14 is melt-bonded and joined with the stem pins 6 inserted through the openings 14a, 15a, 16a, 15b, and 16b. More specifically, the upper presser material 15 and the lower presser material 16 are tightly bonded to both surfaces of the base material 14, and each stem pin 6 is connected to each opening 15 a of the upper presser material 15 and the lower presser material 16. , 16a, 15b, 16b, and a recess 5a having a base material 14 as a bottom surface around the entire perimeter of each stem pin 6 on both the upper (inner) surface and the lower (outer) surface of the stem 5. Each stem pin 6 is formed in close contact with the base material 14 at the bottom surface of the recess 5a.

  Next, an example of manufacturing the stem 5 configured as described above will be described with reference to FIGS.

  In manufacturing the stem 5, as shown in FIGS. 7A and 7B, the base material 14, the upper presser material 15, the lower presser material 16, and the stem pins 6 are sandwiched and held in a positioned state. A pair of positioning jigs 18 are used.

  The positioning jig 18 is a block-shaped member made of high heat-resistant carbon having a melting point of, for example, 1100 degrees or more, and an insertion hole 18a for inserting and supporting the stem pin 6 is provided on one surface side of each stem pin 6. It is formed corresponding to the arrangement of. Further, in each insertion hole 18a, the opening edge portion of the insertion hole 18a corresponding to the large diameter opening 15b of the upper presser member 15 and the large diameter opening 16b of the lower presser member 16 is in the large diameter openings 15b and 16b. The upper presser material 15 and the lower presser material 16 are positioned with respect to the base material 14 so that the stem pins 6 passing through the base material 14 and the respective openings 15a and 16a are coaxial with each other. A protrusion 18b is formed.

  When the stem 5 is set using the positioning jig 18, first, one of the positioning jigs 18 (the lower side in the drawing) is placed on the work surface (not shown) with the protrusion 18 b facing the upper surface. The stem pins 6 are inserted into the insertion holes 18a of the positioning jig 18 and fixed. Next, while passing each stem pin 6 fixed to the positioning jig 18 through the opening 16 a, the large-diameter opening 16 b is inserted into the protrusion 18 b of the positioning jig 18, and the lower part is placed on the positioning jig 18. The side presser material 16 is placed. Further, the openings 14a and 15a and the large diameter opening 15b are roughly aligned with the axial positions of the openings 14a and 15a and the large diameter opening 15b with respect to the openings 16a and the large diameter opening 16b of the lower presser member 16, respectively. After the base material 14 and the upper presser material 15 are superposed in this order on the lower presser material 16 through the stem pins 6, the ring-shaped side tube 7 is fitted into the base material 14. Finally, while inserting each stem pin 6 protruding from the upper presser material 15 into the insertion hole 18a, the protrusion 18b is inserted into the large-diameter opening 15b of the upper presser member 15 and the other ( The positioning jig 18 on the upper side in the figure is placed. Thereby, the setting of the stem 5 is completed. The ring-shaped side tube 7 and each stem pin 6 to be set are subjected to surface oxidation treatment in advance in order to improve the weldability with the base material 14.

  Subsequently, the set stem 5 together with the positioning jig 18 is put into an electric furnace (not shown), and the temperature is higher than the melting point of the base material 14 and is about 850 ° to 900 ° C. The temperature is lower than the melting point of 16), and sintering is performed while pressing the stem 5 with the positioning jig 18. By this sintering process, as shown in FIGS. 8A and 8B, only the base material 14 having a melting point of about 780 degrees is melted, and the base material 14, each presser material 15, 16, and the base material are melted. 14 and each stem pin 6, and the base material 14 and the ring-shaped side tube 7 are fused. At this time, the base material 14 is adjusted to have a large volume in order to improve the adhesion to each component. However, as shown in FIG. 8B, the base material 14 is greatly increased by the end face of the protrusion 18b of the positioning jig 18. The base material 14 is positioned in the height direction in the radial openings 15 b to 16 b, and the excess volume of the molten base material 14 is released into the base material leaching opening 16 c of the lower presser material 16. After the sintering process is completed, the stem 5 is taken out from the electric furnace, and the upper and lower positioning jigs 18 are removed, whereby the manufacture of the stem 5 is completed.

  According to such a manufacturing method of the stem 5, the protrusion 18 b of the positioning jig 18 is caused to enter the large diameter opening 15 b of the upper presser material 15 and the large diameter opening 16 b of the lower presser material 16, thereby Since the upper presser material 15 and the lower presser material 16 can be easily positioned with respect to 14, the manufacturing process is simplified and the manufacturing cost is reduced. The positioning jig 18 also ensures the coaxiality between each stem pin 6 and each opening 15a, 16a. Then, the dynode 10, the convergence electrode 11, and the anode 12 stacked on the inner (upper) surface of the stem 5 of the stem set obtained in this way are connected to the dynode connection piece 10 a, the anode connection piece 12 a, and the convergence electrode. 11 is fixed by welding each of the protruding pieces 11a provided to 11 and the stem pins 6 corresponding thereto, and the side tube 2 to which the light receiving face plate 3 is fixed is attached to the ring-shaped side tube 7 in a vacuum state. By assembling with fixing by welding, a so-called head-on type photomultiplier tube 1 shown in FIGS. 1 to 3 is obtained.

  According to such a configuration of the photomultiplier tube 1, the upper pressing member 15, which is an upper (inner side) member of the stem 5 in the stem 5, has an insulating property, and the edge near the anode pin 13. The portion has a chamfered shape 15c (see FIG. 5). The effect | action of the structure which concerns is demonstrated in detail using FIG.9 and FIG.10.

  FIG. 9 is an enlarged cross-sectional view of the main part showing the vicinity of the anode pin 13 in the present embodiment, and FIG. 10 is an enlarged cross-sectional view of the main part showing the vicinity of the anode pin 13 in the comparative example. In the comparative example, the recess 5a is not formed in the penetrating portion of the stem 5 including the anode pin 13 in the stem 5, and the upper pressing member 17 in which the chamfered shape 15c is not formed in the vicinity of the anode pin 13 is used. Yes. For convenience of explanation, each member is indicated by a broken line.

  As shown in FIG. 9, in this embodiment, in the vicinity of the anode pin 13, the conductive anode pin 13, the insulating base material 14 joined with the stem pin 6 including the anode pin 13, and the triple junction that is a point where the vacuum intersects. The creepage distance Y1 along the insulator from X1 to the ring-shaped side tube 7 is compared with the case of using the upper pressing member 17 in which the chamfered shape 15c is not formed near the anode pin 13 as in the comparative example shown in FIG. Thus, the upper presser member 15 is elongated by a distance along the chamfered shape 15c. In this way, the creepage distance Y1 is lengthened, so that dielectric breakdown and leakage current caused by creeping discharge in the vicinity of the anode pin 13 are sufficiently prevented, and noise is mixed into the electrical signal extracted from the anode pin 13. Prevention is achieved.

  Further, in the present embodiment, the entire periphery of the penetrating portion of the stem pin 6 including the anode pin 13 on the upper (inner) surface of the stem 5 is the recess 5a having the base material 14 as the bottom surface. The creepage distance Y1 is further increased by the height of the recess 5a compared to the creepage distance Y2 along the insulator from the triple junction X2 to the side tube 2 in the comparative example shown in FIG. Therefore, the occurrence of creeping discharge in the vicinity of the anode pin 13 is further suppressed, and the mixing of noise with respect to the electric signal taken out from the anode pin 13 is more effectively achieved. Similarly, with respect to the other stem pins 6 except the anode pin 13, the creeping distance is increased by the height of the recess 5a, so that the occurrence of creeping discharge is suppressed and the voltage tolerance of the photomultiplier tube 1 is increased. It is done. Since the creeping distance along the insulator between the stem pins 6 and 6 is increased at the same time by the formation of the recess 5a, the voltage resistance of the photomultiplier tube 1 is further increased.

  Furthermore, in the present embodiment, the above-described recess 5a is formed, so that the triple junction X1 is located at the joint edge between the bottom surface of the recess 5a and the stem pin 6 including the anode pin 13, and is hidden in the recess 5a. It is in such a state. By concealing the triple junction X1 in the recess 5a in this way, the occurrence of creeping discharge is generated as compared with the case where the upper surface of the upper presser member 17 is exposed as in the triple junction X2 in the comparative example shown in FIG. Is further suppressed, and the voltage tolerance of the photomultiplier tube 1 is further enhanced.

  In addition, since the coaxiality of each stem pin 6 and each opening 15a of the upper pressing member 15 and each opening 16a of the lower pressing member 16 is ensured by the positioning jig 18, the stem pin 6 has inner walls of the openings 15a and 16a. Therefore, the triple junction X1 can be reliably concealed in the recess 5a, and the voltage resistance of the photomultiplier tube 1 is further ensured.

  In the photomultiplier tube 1, the stem 5 is joined to the base material 14, the upper presser material 15 joined to the upper side (inner side) of the base material 14, and the lower side joined to the lower side (outer side) of the base material 14. Since the three-layer structure is formed by the side pressing member 16, the positional accuracy, flatness, and levelness of both surfaces of the stem 5 are increased. As a result, in the photomultiplier tube 1, the positional accuracy between the electron multiplier 9 and the photocathode 4 installed on the upper surface (inner surface) of the stem 5 and the seating property of the electron multiplier 9 are improved. Therefore, characteristics such as photoelectric conversion efficiency can be satisfactorily obtained, and the dimensional accuracy of the entire length of the photomultiplier tube 1 and the mountability when the photomultiplier tube 1 is surface-mounted are improved.

  In addition, since the base material leaching opening 16c (see FIG. 6) is formed in the lower presser material 16, an excessive volume of the molten base material 14 can be released into the base material leaching opening 16c satisfactorily. For this reason, when the base material 14 is melted, the base material 14 hardly protrudes from the surface of the stem 5 through the opening 15a of the upper pressing material 15 and the opening 16a of the lower pressing material 16, and the positional accuracy of both surfaces of the stem 5 is increased. Flatness and levelness are ensured.

  Furthermore, in the photomultiplier tube 1, as described above, the entire periphery of the penetrating portion of the stem pin 6 on both surfaces of the stem 5 is a recess 5 a having the base material 14 as a bottom surface. As a result, the joining edge of the base material 14 to the stem pin 6 becomes the bottom surface of the recess 5a formed in the stem 5, and the base material 14 joins the stem pin 6 at a gentle angle (almost right angle) and bends to the stem pin 6. The stem pin 6 comes into contact with the peripheral edge portion on the open side of the recess 5a even if the sag acts, and further bending of the stem pin 6 is prevented, so that cracks are generated on both sides of the joint portion between the base material 14 and the stem pin 6. This prevents the airtightness and good appearance of the sealed container 8.

  The present invention is not limited to the above embodiment. For example, the chamfered shape formed on the upper pressing member 15 may be formed over the entire circumference of the edge of the upper pressing member 15 including the vicinity of the anode pin 13. Further, the upper pressing member 15 may be a stepped disk shape having a chamfered shape over the entire circumference of the edge portion on the upper surface side, and various modifications can be applied. That is, when forming a chamfered shape that is a right angle to the end surface (upper and lower surfaces) of the upper presser member 15 like the chamfered shape 15c shown in FIG. 5, as shown in FIG. A chamfered shape 15d may be used, and as shown in FIG. 12, in addition to a linear chamfered shape, the vicinity of the anode pin 13 may be further chamfered in a semicircular shape up and down. Further, as shown in FIG. 13, only the vicinity of the anode pin 13 may be a chamfered shape 15 f that penetrates in a semicircular shape in the vertical direction. Further, as shown in FIG. 14, in addition to the linear chamfered shape, the vicinity of the anode pin 13 may be further chamfered in a rectangular shape 15g, and as shown in FIG. It is good also as the chamfering shape 15h which penetrated only the vicinity in the rectangular shape up and down. Further, as shown in FIG. 16, in addition to the V-shaped chamfered shape, a chamfered shape 15i in which the vicinity of the anode pin 13 is linear may be used.

  Further, the chamfered shape does not necessarily have to be a right-angled surface with respect to the end surface of the upper presser material 15, and as shown in FIG. 17, it may be a chamfered shape 15j that is inclined with respect to the end surface of the upper presser material 15, As shown in FIG. 18, it is good also as the chamfering shape 15k which makes only an upper part an inclined surface, and as shown in FIG. 19, it is good also as a stepped chamfering shape 15l with a large lower side. Moreover, as shown in FIG. 20, it is good also as the chamfering shape 15m which makes only a lower part an inclined surface, and it is good also as a chamfering shape 15n which makes only an intermediate part an inclined surface as shown in FIG. Further, as modified examples of the chamfered shapes 15m and 15n, as shown in FIGS. 22 and 23, as a chamfered shape 15o and a chamfered shape 15p configured such that the lower surface side of the upper presser member 15 contacts the ring-shaped side tube 7. Also good. According to any of the modifications shown in FIGS. 11 to 23, the creeping distance in the vicinity of the anode pin 13 can be increased, and noise can be prevented from being mixed into the electric signal taken out from the anode pin 13.

  Further, for example, another layer may be provided on the upper surface of the upper presser material 15 so that the entire stem 5 has four or more layers, and the electron multiplying portion 9 may be installed on the upper surface of this other layer. When the layer is provided with an opening through which the stem pin 6 joined to the base material 14 is inserted, this another layer is used as an insulator, and at least the chamfered shape as described above is formed in the vicinity of the anode pin 13 of this other layer. Form. Further, in the case where the opening for inserting the stem pin 6 is provided in another layer as described above, at least two of the openings are other openings so that the positioning jig 18 can enter the base material 14. It is preferable to adopt a configuration having a larger diameter.

  Moreover, in the said embodiment, although the base material leaching opening 16c is provided only in the lower side pressing material 16, such a base material leaching opening should just be provided in at least one of the pressing materials, for example, the upper pressing material 15 It may be provided only on the upper presser material 15 or the lower presser material 16.

  Furthermore, as a modification of the present embodiment, as shown in FIG. 24, a photomultiplier tube 20 in which a metal exhaust pipe 19 is provided in the central portion of the stem 5 may be employed. 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. As yet another modification, as shown in FIG. 25, a side tube 27 that is longer than the side tube 2 is fitted into a ring-shaped side tube 7 having a flange portion at its lower end, and the flange portions are welded together. You may employ | adopt the photomultiplier tube 26 which has the fixed structure.

  Next, an example of a radiation detection apparatus provided with the photomultiplier tube 1 shown in FIGS. 1 to 3 will be described. In the radiation detection apparatus 21 according to the example shown in FIGS. 26 and 27, a scintillator 22 that converts radiation into light and emits it is installed outside the light receiving face plate 3 of the photomultiplier tube 1, and the photomultiplier tube 1 is The processing circuit 23 is mounted on a circuit board 24 provided on the lower surface side. Further, in the radiation detection apparatus 25 according to another example shown in FIG. 28 and FIG. 29, the processing circuit 23 is installed on the circuit board 24, and the photomultiplier tube 1 is formed so as to surround the processing circuit 23 with the stem pins 6. It is mounted on the circuit board 24. With the configuration as described above, the above-described operational effects can be obtained, and radiation detection devices 21 and 25 that are particularly suitable for surface mounting can be obtained.

[Second Embodiment]
As shown in FIG. 30, in the photomultiplier tube 28 according to the second embodiment, a stem 29 is joined to a disk-like base material 30 having the same quality as the base material 14 and the upper side (inside) of the base material 30. The photomultiplier according to the first embodiment in which the stem 5 has a three-layer structure of the base material 14, the upper presser material 15 and the lower presser material 16 in that the upper presser material 15 has a two-layer structure. Different from the double tube 1.

  That is, the lower pressing member 16 is not provided on the stem 29 of the photomultiplier tube 28, and the upper half of the base member 30 is substantially the same as the outer diameter of the stem pin 6 as shown in FIG. Further, as shown in FIG. 32, a plurality (15) of openings 30 a having a lower half larger than the outer diameter of the stem pin 6 are formed along the outer peripheral portion of the base material 30. In addition, among the openings 30a of the base member 30, the predetermined four places including the openings 30a through which the anode pins 13 pass have lower half outer diameters below the other openings 30a so that the positioning jig 18 can enter. The large-diameter opening 30b has a larger diameter than the half outer diameter. Furthermore, a circular base material leaching recess 30c (see FIG. 33) is formed in the lower central portion of the base material 30 as a base material leaching portion from which the base material 30 is leached by melting.

  Then, as shown in FIG. 30, the base member 30 and the upper presser member 15 are overlapped in a state where the axial centers of the openings 30a and 15a and the large-diameter openings 30b and 15b are aligned with each other. The base material 30 is fusion-bonded by melting the stem pin 6 with the stem pin 6 inserted through the 15a and the large-diameter openings 30b and 15b. More specifically, the upper presser material 15 is closely bonded to the upper surface of the base material 30, and each stem pin 6 opens the lower half of each opening 30 a of the base material 30 and each opening 15 a of the upper presser material 15. A concave portion 29a having a base material 30 as a bottom surface is formed around the entire through portion of each stem pin 6 on both the upper (inner) surface and the lower (outer) surface of the stem 29. The bottom surface of the recess 29a is in close contact with and bonded to the base material 30.

  In manufacturing the stem 29 as described above, the same method as that of the stem 5 according to the first embodiment can be used. Specifically, as shown in FIG. 33, first, one of the positioning jigs 18 (the lower side in the figure) is placed on a work surface (not shown) with the protrusion 18b facing the upper surface, The stem pins 6 are inserted and fixed in the insertion holes 18a of the jig 18, respectively. Next, each stem pin 6 fixed to the positioning jig 18 is passed through the opening 30a, and the projection 18b of the positioning jig 18 is large. The base material 30 is placed on the positioning jig 18 by entering the diameter opening 30b, and each opening 15a and each large-diameter opening 15b with respect to each opening 30a and each large-diameter opening 30b of the base material 30. The upper presser member 15 is superimposed on the base member 30 through the stem pin 6 in each opening 15a and each large-diameter opening 15b while roughly aligning the axial center position of the ring, and then the ring-shaped side tube 7 is fitted into the base member 30. The most Further, while inserting each stem pin 6 protruding from the upper presser material 15 into the insertion hole 18a, the protrusion 18b is inserted into the large-diameter opening 15b of the upper presser member 15 and the other (illustrated) on the upper presser member 15 is shown. The upper) positioning jig 18 is placed. Thereby, the setting of the stem 29 is completed. As in the case of the first embodiment, the ring-shaped side tube 7 and each stem pin 6 to be set are subjected to surface oxidation treatment in advance in order to improve the weldability with the base material 30.

  Next, the set stem 29 is put into an electric furnace, and a sintering process is performed under the same conditions as described above. By this sintering process, as shown in FIGS. 34 (a) and 34 (b), the base material 30 and the upper presser material 15, the base material 30 and each stem pin 6, and the base material 30 and the ring-shaped side tube 7 Are fused by melting of the base material 30. At this time, as shown in FIG. 34 (b), the base material 30 is positioned in the height direction in the large-diameter openings 30b and 15b by the end surfaces of the protrusions 18b of the positioning jig 18, and the base material is melted. The 14 extra volumes are released into the base material leaching recess 30c. After the sintering process is completed, the stem 29 is taken out from the electric furnace, and the upper and lower positioning jigs 18 are removed, whereby the manufacture of the stem 29 is completed.

  According to such a manufacturing method of the stem 29, the upper pressing member 15 can be easily positioned with respect to the base material 30 by the positioning jig 18, as in the first embodiment, and thus the manufacturing process is simplified. Manufacturing cost can be reduced. Moreover, the coaxiality of each stem pin 6 and each opening 15a is ensured by the positioning jig 18. Then, the dynode 10, the convergence electrode 11, and the anode 12 stacked on the inner (upper) surface of the stem 29 of the stem set thus obtained are connected to the dynode connection piece 10 a, the anode connection piece 12 a, and the convergence electrode. 11 is fixed by welding each of the protruding pieces 11a provided to 11 and the stem pins 6 corresponding thereto, and the side tube 2 to which the light receiving face plate 3 is fixed is attached to the ring-shaped side tube 7 in a vacuum state. A head-on type photomultiplier tube 28 shown in FIG. 30 is obtained by assembling with fixing by welding.

  Also in the photomultiplier tube 28 configured in this manner, the upper presser material 15 that is a member on the upper side (inside) of the base material 30 in the stem 29 is provided in the same manner as the photomultiplier tube 1 according to the first embodiment. In addition to having insulating properties, the edge near the anode pin 13 has a chamfered shape 15c (see FIG. 5), so that the creepage distance near the anode pin 13 is lengthened and causes creeping discharge. Insulation breakdown and leakage current are sufficiently prevented, and noise can be prevented from being mixed into the electric signal taken out from the anode pin 13. In addition, regarding the chamfered shape 15c, also in this embodiment, the chamfered shape 15c may be formed over the entire circumference of the edge portion of the upper presser material 15, or may be a stepped disk shape. Can be applied.

  Further, since the entire periphery of the penetrating portion of the stem pin 6 including the anode pin 13 on the upper (inner) surface of the stem 29 is a recess 29a having the base material 30 as the bottom surface, the creeping distance related to the vicinity of the anode pin 13 is further increased. It is possible to more effectively prevent noise from being mixed into the electrical signal which is elongated and is taken out from the anode pin 13. Further, the creepage distance is similarly increased with respect to the other stem pins 6 except the anode pin 13, so that the voltage tolerance of the photomultiplier tube 28 is enhanced. Incidentally, the formation of the recess 29a simultaneously increases the creeping distance along the insulator between the stem pins 6 and 6, and further, the triple junction is concealed in the recess 29a, so that the voltage resistance of the photomultiplier tube 28 is increased. Is more enhanced.

  As in the first embodiment, since the coaxiality between each stem pin 6 and each opening 15a of the upper pressing member 15 is ensured by the positioning jig 18, the triple junction can be reliably hidden in the recess 29a. The voltage tolerance of the photomultiplier tube 28 is further ensured.

  In the photomultiplier tube 28, the stem 29 has a two-layer structure including the base material 29 and the upper presser material 15 joined to the upper side (inner side) of the base material 29, so that the position of the upper surface of the stem 29 is Increases accuracy, flatness and levelness. As a result, in the photomultiplier tube 28, the positional accuracy between the electron multiplier 9 and the photocathode 4 installed on the upper surface (inner surface) of the stem 29 and the seating property of the electron multiplier 9 are improved. Therefore, characteristics such as photoelectric conversion efficiency can be obtained satisfactorily.

  Furthermore, since the base material leaching recess 30c (see FIG. 33) is formed in the base material 30, an excessive volume of the molten base material 30 can be released into the base material leaching recess 30c satisfactorily. For this reason, when the base material 30 is melted, the base material 30 hardly protrudes from the surface of the stem 29 through the opening 15 a of the upper presser material 15 and the lower half of the opening 30 a of the base material 30. Accuracy, flatness and levelness are ensured.

  Also in the photomultiplier tube 28, as described above, the entire periphery of the penetrating portion of the stem pin 6 on the upper (inner) surface and the lower (outer) surface of the stem 29 is a recess 29a having the base material 30 as the bottom surface. Therefore, the occurrence of cracks on both sides of the joint portion between the base material 30 and the stem pin 6 is prevented, and the hermeticity and good appearance of the sealed container 8 are ensured.

  As a modification of the present embodiment, a structure in which a metal exhaust pipe 19 is provided in the central portion of the stem 29 may be employed as in the photomultiplier tube 20 shown in FIG. Similarly to the photomultiplier tube 26 shown in FIG. 25, a ring-shaped side tube 7 having a flange portion at its lower end is fixed to the stem 29, and the ring-shaped side tube 7 is longer than the side tube 2. A configuration in which the side pipes 27 are fitted together and the respective flange portions are fixed by welding may be employed.

  In this embodiment, a base material leaching recess 30c as a base material leaching portion is provided in the lower portion of the base material 30. Such a base material leaching portion is provided on at least one of the base material 30 and the upper presser material 15. For example, only the upper presser material 15 may be provided with a base material leaching opening similar to that described in the first embodiment, or the upper presser material 15 may be provided with a base material leaching opening. The material 30 may be provided with a base material leaching recess 30c.

  Further, when configuring the radiation detection apparatus provided with the photomultiplier tube 28 shown in FIG. 30, the configuration is the same as that of the radiation detection apparatuses 21 and 25 shown in FIG. 26 to FIG. 27 and FIG. Thus, the above-described effects can be obtained, and a radiation detection device suitable for surface mounting can be obtained.

  As yet another modification of the present embodiment, a two-layered stem may be configured by joining a presser material to the lower surface (outer surface) of the base material. In the photomultiplier tube 31 according to this another modified example, as shown in FIG. 35, the stem 32 is disposed on the lower side (outside) of the disk-like base material 33 having the same quality as the base material 14 and the base material 33. A two-layer structure is formed by the joined lower pressing member 16.

  That is, the upper pressing member 15 is not provided on the stem 32 of the photomultiplier tube 31, and the lower half of the base member 33 is substantially the same as the outer diameter of the stem pin 6, as shown in FIG. As shown in FIG. 36, a plurality (15) of openings 33 a whose upper half is larger than the outer diameter of the stem pin 6 are formed along the outer periphery of the base member 33. Further, among the openings 33a of the base member 33, the upper half outer diameter of the predetermined three places excluding the opening 33a through which the anode pin 13 passes has an upper half outer diameter above the other openings 33a to allow the positioning jig 18 to enter. The large-diameter opening 33b is larger than the half outer diameter. Further, the base material 33 has a chamfered shape 33c on the upper surface side in the vicinity of the opening 33a through which the anode pin 13 passes.

  Then, as shown in FIG. 35, the base material 33 and the lower presser material 16 are overlapped with the positions of the axial centers of the openings 33a and 16a and the large-diameter openings 33b and 16b being aligned. The base material 33 is fusion-bonded by melting the stem pin 6 with the stem pins 6 inserted through the large-diameter openings 33b and 16b. More specifically, the lower pressing member 16 is in close contact with and joined to the lower surface of the base member 33, and each stem pin 6 is connected to the upper half of each opening 33 a of the base member 33 and each opening of the lower pressing member 16. A recess 32a having a base material 33 as a bottom surface is formed around the entire perimeter of each stem pin 6 on both the upper (inner) surface and the lower (outer) surface of the stem 32. 6 is closely bonded to the base member 33 at the bottom surface of the recess 32a.

  Also in the manufacture of such a stem 32, the same method as the stem 5 according to the first embodiment can be used. Specifically, first, as shown in FIG. 38, one of the positioning jigs 18 (the lower side in the figure) is placed on the work surface (not shown) with the projection 18b facing the upper surface, and the positioning jig 18 is positioned. The stem pins 6 are inserted and fixed in the insertion holes 18a of the jig 18, respectively. Next, each stem pin 6 fixed to the positioning jig 18 is passed through the opening 16a, and the projection 18b of the positioning jig 18 is large. The lower pressing member 16 is placed on the positioning jig 18 by entering the diameter opening 16b, and each opening 33a and each large opening 16b of the lower pressing member 16 is further placed. The base material 33 is overlaid on the lower presser material 16 through the stem pin 6 through each of the openings 33a and each large diameter opening 33b while roughly aligning the axial center position of the large diameter opening 33b. Fit side tube 7 Finally, while inserting each stem pin 6 protruding from the base material 33 into the insertion hole 18a, the protruding portion 18b is inserted into the large-diameter opening 33b of the base material 33 and the other (upper side in the figure) is placed on the base material 33. The positioning jig 18 is placed. Thereby, the setting of the stem 32 is completed. As in the case of the first embodiment, the ring-shaped side tube 7 and each stem pin 6 to be set are subjected to surface oxidation treatment in advance in order to improve the weldability with the base material 33.

  Next, the set stem 29 is put into an electric furnace, and a sintering process is performed under the same conditions as described above. By this sintering process, as shown in FIGS. 39A and 39B, the base material 33 and the lower presser material 16, the base material 33 and each stem pin 6, and the base material 33 and the ring-shaped side tube 7 are used. Are fused by melting the base material 33. At this time, as shown in FIG. 39 (b), the base material 33 is positioned in the height direction in the large-diameter openings 33b and 16b by the end face of the projection 18b of the positioning jig 18, and the molten base material is obtained. 33 excess volumes are released into the base material leaching opening 16c. After the sintering process is completed, the stem 32 is taken out from the electric furnace, and the upper and lower positioning jigs 18 are removed, whereby the manufacture of the stem 32 is completed.

  According to such a method of manufacturing the stem 32, the lower pressing member 16 can be easily positioned with respect to the base material 33 by the positioning jig 18, as in the first embodiment, and thus the manufacturing process is simplified. Thus, the manufacturing cost can be reduced. Moreover, the coaxiality of each stem pin 6 and each opening 16a is also ensured by the positioning jig 18. Then, the dynode 10, the convergence electrode 11, and the anode 12 stacked on the inner (upper) surface of the stem 32 of the stem set thus obtained are connected to the dynode connection piece 10 a, the anode connection piece 12 a, and the convergence electrode. 11 is fixed by welding each of the protruding pieces 11a provided to 11 and the stem pins 6 corresponding thereto, and the side tube 2 to which the light receiving face plate 3 is fixed is attached to the ring-shaped side tube 7 in a vacuum state. A head-on type photomultiplier 31 shown in FIG. 35 is obtained by welding and assembling.

  Also in the photomultiplier tube 31 configured as described above, the base material 33 itself has an insulating property in the stem 32, and the edge on the upper surface side in the vicinity of the anode pin 13 has the photomultiplier according to the first embodiment. Since the chamfered shape 33c (see FIG. 36) is the same as that of the double tube 1, the creepage distance in the vicinity of the anode pin 13 is lengthened to sufficiently prevent dielectric breakdown and leakage current caused by creeping discharge. Thus, it is possible to prevent noise from being mixed into the electric signal taken out from the anode pin 13. In addition, regarding the chamfered shape 33c, it may be formed over the entire circumference of the edge portion on the upper surface side of the base material 33, and various modifications shown in FIGS. 11 to 23 can be applied.

  Further, since the entire periphery of the penetrating portion of the stem pin 6 including the anode pin 13 on the upper (inner) surface of the stem 32 is a recess 32a having the base material 33 as the bottom surface, the creeping distance in the vicinity of the anode pin 13 is further increased. It is possible to more effectively prevent noise from being mixed into the electrical signal which is elongated and is taken out from the anode pin 13. The formation of the concave portion 32a simultaneously increases the creeping distance along the insulator between the stem pins 6 and 6, and the triple junction is concealed in the concave portion 32a, so that the voltage resistance of the photomultiplier tube 28 is increased. Is more enhanced.

  As in the first embodiment, since the coaxiality between each stem pin 6 and each opening 16a of the lower pressing member 16 is secured by the positioning jig 18, the triple junction can be reliably hidden in the recess 32a. The voltage tolerance of the photomultiplier tube 31 is further ensured.

  Further, in the photomultiplier tube 31, the stem 32 has a two-layer structure including the base material 33 and the lower pressing member 16 joined to the lower side (outside) of the base material 33, so that the lower surface of the stem 32. The positional accuracy, flatness, and levelness of the are increased. As a result, the photomultiplier tube 31 can improve the dimensional accuracy of the entire length of the photomultiplier tube 31 and the mountability when the photomultiplier tube 31 is surface-mounted.

  Further, since the base material leaching opening 16c (see FIG. 6) is formed in the lower presser material 16, the lower presser material 16 is melted when the base material 33 is melted, as in the first embodiment. The base material 33 hardly protrudes from the surface of the stem 32 through the upper half of the opening 16a and the opening 33a of the base material 33, and the positional accuracy, flatness and levelness of both surfaces of the stem 32 are ensured.

  Also in the photomultiplier tube 31, as described above, the entire periphery of the penetrating portion of the stem pin 6 on the upper (inner) surface and the lower (outer) surface of the stem 32 has the base material 33 as the bottom surface 32a. Therefore, the occurrence of cracks on both sides of the joint portion between the base member 33 and the stem pin 6 is prevented, and the hermeticity and good appearance of the sealed container 8 are ensured.

  The photomultiplier tube 31 may also have a structure in which a metal exhaust pipe 19 is provided at the center portion of the stem 32 as in the photomultiplier tube 20 shown in FIG. Similarly to the photomultiplier tube 26 shown in FIG. 25, a ring-shaped side tube 7 having a flange portion at the lower end thereof is fixed to the stem 32, and the ring-shaped side tube 7 is longer than the side tube 2. A configuration in which the side pipes 27 are fitted together and the respective flange portions are fixed by welding may be employed.

  In this embodiment, only the lower presser material 16 is provided with a base material leaching opening 16c as a base material leaching portion. However, such a base material leaching portion is at least of the base material 33 and the lower presser material 16. For example, only the base material 33 may be provided with a base material leaching recess similar to that described above, or the lower pressing material 16 may be provided with a base material leaching opening 16c, and the base material 33 may be provided. A base material leaching recess may be provided.

  Moreover, when configuring the radiation detection apparatus provided with the photomultiplier tube 31, the configuration is the same as that of the radiation detection apparatuses 21 and 25 shown in FIGS. 26 to 27 and FIGS. A radiation detection device that exhibits the effects and is suitable particularly for surface mounting can be obtained.

[Third Embodiment]
As shown in FIG. 40, the photomultiplier tube 34 according to the third embodiment has a stem 5 in which the stem 35 has a single-layer structure made of a disk-like base material 36 that is the same quality as the base material 14. Is different from the photomultiplier tube 1 according to the first embodiment in which the base material 14, the upper pressing material 15, and the lower pressing material 16 have a three-layer structure.

  That is, the upper presser 15 and the lower presser 16 are not provided on the stem 35 of the photomultiplier tube 34, and the intermediate portion of the base member 36 has a stem pin 6 as shown in FIGS. 40 to 42. A plurality (15) of openings 36 a having substantially the same diameter as the outer diameter of the base material 36 and having an upper portion and a lower portion larger than the outer diameter of the stem pin 6 are formed along the outer peripheral portion of the base member 36. In addition, the upper and lower portions of three predetermined portions of the opening 36a excluding the opening 36a through which the anode pin 13 passes and the lower part of the opening 36a through which the anode pin 13 passes are a holding jig having the same configuration as the positioning jig. The outer diameter of the upper part and the lower part is set to be larger than the outer diameters of the upper part and the lower part of the other opening 36a so that 18 can enter. Further, a circular base material leaching recess 36c (see FIG. 43) is formed in the lower central portion of the base material 36 as a base material leaching portion from which the base material 36 is leached by melting. An edge on the upper surface side in the vicinity of the opening 36a that passes through is a chamfered shape 36d.

  As shown in FIG. 40, the base material 36 is fusion bonded to the stem pin 6 by melting the base material 36 in a state where the stem pin 6 is passed through each opening 36a. More specifically, each stem pin 6 passes through the upper part and the lower part of each opening 36a of the base material 36 and penetrates each stem pin 6 on both the upper (inner) surface and the lower (outer) surface of the stem 35. A concave portion 35a having the base material 36 as a bottom surface is formed around the entire periphery of each portion, and each stem pin 6 is in close contact with the base material 36 at the bottom surface of the concave portion 35a.

  When manufacturing such a stem 35, the same method as the stem 5 according to the first embodiment can be used. Specifically, first, as shown in FIG. 43, one side (the lower side in the drawing) of the holding jig 18 having the same configuration as the positioning jig is placed on the work surface (the illustration in the figure) with the projection 18b facing the upper surface. The stem pins 6 are inserted into the insertion holes 18a of the presser jig 18 and fixed, and then the stem pins 6 fixed to the presser jig 18 are passed through the openings 36a while the presser jig 18 is inserted. After the large diameter opening 36b on the lower surface side of the base material 36 is inserted into the protrusion 18b of the base material 36 and the base material 36 is placed on the holding jig 18, the ring-shaped side tube 7 is fitted into the base material 36. Further, while inserting each stem pin 6 protruding from the base material 36 into the insertion hole 18a, the protrusion 18b is inserted into the large-diameter opening 36b on the upper surface side of the base material 36, and the other (illustrated) is placed on the base material 36. Place the upper holding jig 18 That. Thereby, the setting of the stem 35 is completed. As in the case of the first embodiment, the ring-shaped side tube 7 and each stem pin 6 to be set are subjected to surface oxidation treatment in advance in order to improve the weldability with the base material 36.

  Next, the set stem 35 is put into an electric furnace, and a sintering process is performed under the same conditions as described above. 44 (a) and 44 (b), the base material 36 and each stem pin 6, and the base material 36 and the ring-shaped side tube 7 are fused by melting the base material 36. Is done. At this time, as shown in FIG. 44 (b), the end surface of the protrusion 18b of the holding jig 18 positions the base material 36 in the height direction in the large-diameter opening 36b. A large volume is released into the base material leaching recess 36c. After the sintering process is completed, the stem 35 is taken out from the electric furnace, and the upper and lower pressing jigs 18 are removed, whereby the manufacture of the stem 35 is completed.

  According to such a method for manufacturing the stem 35, as described above, the manufacturing process is simplified and the manufacturing cost is reduced. Then, the dynode 10, the convergence electrode 11, and the anode 12 stacked on the inner (upper) surface of the stem 35 of the stem set thus obtained are connected to the dynode connection piece 10 a, the anode connection piece 12 a, and the convergence electrode. 11 is fixed by welding each of the protruding pieces 11a provided to 11 and the stem pins 6 corresponding thereto, and the side tube 2 to which the light receiving face plate 3 is fixed is attached to the ring-shaped side tube 7 in a vacuum state. The electron multiplier 9, the focusing electrode 11, and the anode 12 are welded and fixed, and the side tube 7 to which the light receiving face plate 3 is fixed is welded and fixed in a vacuum state to assemble the head-on type shown in FIG. A photomultiplier tube 34 is obtained.

  Also in the photomultiplier tube 34 configured in this way, the base material 36 itself has an insulating property in the stem 35, and the edge on the upper surface side in the vicinity of the anode pin 13 has the photomultiplier according to the first embodiment. Since the chamfered shape 36d (see FIG. 41) is the same as that of the double tube 1, the creepage distance in the vicinity of the anode pin 13 is lengthened to sufficiently prevent dielectric breakdown and leakage current caused by creeping discharge. Thus, it is possible to prevent noise from being mixed into the electric signal taken out from the anode pin 13. The chamfered shape 36d may be formed over the entire circumference of the edge on the upper surface side of the base material 36, and various modifications shown in FIGS. 11 to 23 can be applied.

  Further, since the entire periphery of the penetrating portion of the stem pin 6 including the anode pin 13 on the upper (inner) surface of the stem 35 is a recess 35a having the base material 36 as a bottom surface, the creeping distance in the vicinity of the anode pin 13 is further increased. It is possible to more effectively prevent noise from being mixed into the electrical signal which is elongated and is taken out from the anode pin 13. The formation of the concave portion 35a simultaneously increases the creeping distance along the insulator between the stem pins 6 and 6, and further, the triple junction is concealed in the concave portion 35a, so that the voltage resistance of the photomultiplier tube 28 is increased. Is more enhanced.

  Furthermore, since the base material leaching recess 36c (see FIG. 43) is formed in the base material 36, an excess volume of the molten base material 36 can be released into the base material leaching recess 36c satisfactorily. For this reason, when the base material 36 is melted, the base material 36 hardly protrudes from the surface of the stem 35 through the upper and lower portions of the opening 36a, and the positional accuracy, flatness, and levelness of both surfaces of the stem 35 are ensured. Yes.

  Also in the photomultiplier tube 34, as described above, the entire periphery of the penetrating portion of the stem pin 6 on the upper (inner) surface and the lower (outer) surface of the stem 35 is a recess 35a having the base material 36 as a bottom surface. Therefore, the occurrence of cracks on both sides of the joint portion between the base material 36 and the stem pin 6 is prevented, and the hermeticity and good appearance of the sealed container 8 are ensured.

  The photomultiplier tube 34 may also have a structure in which a metal exhaust pipe 19 is provided at the center portion of the stem 35 as in the photomultiplier tube 20 shown in FIG. Similarly to the photomultiplier tube 26 shown in FIG. 25, a ring-shaped side tube 7 having a flange portion at its lower end is fixed to the stem 35, and the ring-shaped side tube 7 is longer than the side tube 2. A configuration in which the side pipes 27 are fitted together and the respective flange portions are fixed by welding may be employed.

  In this embodiment, the base material leaching recess 36 c as a base material leaching portion is provided in the lower portion of the base material 36, but such a base material leaching portion may be provided in the upper portion of the base material 36.

  Further, in the case of configuring a radiation detection apparatus provided with this photomultiplier tube 34, the above-described configuration is the same as that of the radiation detection apparatuses 21 and 25 shown in FIGS. 26 to 27 and FIGS. A radiation detection device that exhibits the effects and is suitable particularly for surface mounting can be obtained.

It is a top view which shows the photomultiplier tube which concerns on 1st Embodiment of 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 a top view of the base member which constitutes the stem concerning a 1st embodiment. It is a top view of the upper pressing material which constitutes the stem concerning a 1st embodiment. It is a top view of the lower side presser material which comprises the stem which concerns on 1st Embodiment. It is the figure which showed the manufacture example of the stem which concerns on 1st Embodiment, (a) is a sectional side view which shows the state of the stem before sintering, (b) is the principal part enlarged view. It is the figure which showed the manufacture example of the stem which concerns on 1st Embodiment, (a) is a sectional side view which shows the state of the stem after sintering, (b) is the principal part enlarged view. FIG. 4 is an enlarged view of a main part in the vicinity of an anode pin showing triple junction and creepage distance in the photomultiplier shown in FIG. 3. It is the principal part enlarged view of the anode pin vicinity which showed the triple junction and creepage distance in a comparative example. It is the figure which showed the modification of the chamfering shape. It is the figure which showed another modification of the chamfering shape. It is the figure which showed another modification of the chamfering shape. It is the figure which showed another modification of the chamfering shape. It is the figure which showed another modification of the chamfering shape. It is the figure which showed another modification of the chamfering shape. It is the figure which showed another modification of the chamfering shape. It is the figure which showed another modification of the chamfering shape. It is the figure which showed another modification of the chamfering shape. It is the figure which showed another modification of the chamfering shape. It is the figure which showed another modification of the chamfering shape. It is the figure which showed another modification of the chamfering shape. It is the figure which showed another modification of the chamfering shape. It is the sectional side view which showed the photomultiplier tube which concerns on a modification. It is the sectional side view which showed the photomultiplier tube which concerns on another modification. It is a side view which shows an example of a radiation detection apparatus. It is principal part sectional drawing of the radiation detection apparatus shown in FIG. It is a side view which shows the other example of a radiation detection apparatus. It is principal part sectional drawing of the radiation detection apparatus shown in FIG. It is a sectional side view of the photomultiplier tube concerning 2nd Embodiment of this invention. It is a top view of the base member which constitutes the stem concerning a 2nd embodiment. It is a bottom view of the base member which constitutes the stem concerning a 2nd embodiment. It is the figure which showed the manufacture example of the stem which concerns on 2nd Embodiment, (a) is a sectional side view which shows the state of the stem before sintering, (b) is the principal part enlarged view. It is the figure which showed the manufacture example of the stem which concerns on 2nd Embodiment, (a) is a sectional side view which shows the state of the stem after sintering, (b) is the principal part enlarged view. It is a sectional side view of the photomultiplier tube which concerns on the modification of 2nd Embodiment. It is a top view of the base member which constitutes the stem concerning the modification of a 2nd embodiment. It is a bottom view of the base member which constitutes the stem concerning the modification of a 2nd embodiment. It is the figure which showed the manufacture example of the stem which concerns on the modification of 2nd Embodiment, (a) is a sectional side view which shows the state of the stem before sintering, (b) is the principal part enlarged view. It is the figure which showed the example of manufacture of the stem which concerns on the modification of 2nd Embodiment, (a) is a sectional side view which shows the state of the stem after sintering, (b) is the principal part enlarged view. It is a sectional side view of the photomultiplier tube concerning a 3rd embodiment. It is a top view of the base member which constitutes the stem concerning a 3rd embodiment. It is a bottom view of the base member which constitutes the stem concerning a 3rd embodiment. It is the figure which showed the manufacture example of the stem which concerns on 3rd Embodiment, (a) is a sectional side view which shows the state of the stem before sintering, (b) is the principal part enlarged view. It is the figure which showed the manufacture example of the stem which concerns on 3rd Embodiment, (a) is a sectional side view which shows the state of the stem after sintering, (b) is the principal part enlarged view.

Explanation of symbols

  1, 20, 26, 28, 31, 34 ... Photomultiplier tubes, 2, 27 ... Side tubes, 3 ... Light receiving face plate, 4 ... Photocathode, 5, 29, 32, 35 ... Stem, 6 ... Stem pin, 7 ... Ring-shaped side tube (side tube), 8 ... sealed container, 9 ... electron multiplier, 12 ... anode (anode), 13 ... anode pin (stem pin), 14, 30, 33, 36 ... base material, 15 ... upper side Presser material (presser material), 15c to 15p, 33c, 36d ... chamfered shape, 16 ... lower presser material (presser material), 18 ... positioning jig, presser jig, 21, 25 ... radiation detection device, 22 ... Scintillator.

Claims (4)

A photoelectric surface provided in a sealed container in a vacuum state and converting incident light incident through a light receiving surface plate constituting one end of the sealed container into electrons, and provided in the sealed container. An electron multiplier for multiplying electrons emitted from the surface, an anode for taking out the electrons multiplied by the electron multiplier as an output signal, and a stem constituting the other end of the sealed container A plurality of stem pins inserted into the stem and led out from the sealed container and electrically connected to the anode and the electron multiplier, and a photomultiplier tube comprising:
Comprising a side tube having conductivity to constitute the sealed container and surround the stem from its side;
The stem has an insulating base material that penetrates and joins a stem pin including an anode pin electrically connected to the anode,
The photomultiplier according to claim 1, wherein an inner edge of the base material in the vicinity of the anode pin is chamfered. The stem includes the base material;
A presser material that is bonded to either the inner surface or the outer surface of the base material and passes the stem pin bonded to the base material, and has a two-layer structure.
When the presser material is joined to the inner surface of the base material, the presser material has insulating properties, and the chamfered shape is provided on the inner edge of the presser material near the anode pin. The photomultiplier tube according to claim 1, wherein the photomultiplier tube is provided. The stem includes the base material;
The base material is bonded to both the inner surface and the outer surface, respectively, and has a structure of three or more layers including at least a presser material that passes the stem pin bonded to the base material.
The member through which the anode pin passes through the member inside the base material has an insulating property, and the chamfered shape is an inner edge in the vicinity of the anode pin of the member through which the anode pin passes through the member inside the base material. The photomultiplier tube according to claim 1, wherein the photomultiplier tube is provided in a portion. A radiation detection apparatus comprising a scintillator that converts radiation into light and emits it outside the light-receiving face plate of the photomultiplier tube according to claim 1.

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