JP2013181800A - Particle beam position detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inhibit large current from flowing along the surface of a ceramic substrate between an electrode post and an electrode.SOLUTION: A particle beam position detector 10 is a detector including a ceramic substrate 11, a first electrode 12 arranged one principal plane of the ceramic substrate 11, a second electrode 14 arranged on the other principal plane, and a metal post 13 arranged in a through hole 20 arranged in the shape of a matrix and connected to the first electrode 12 to detect the position of a neutron beam made incident on a measuring target space by detecting electric charge made incident on the second electrode 14 and electric charge made incident on the first electrode 12 through the electrode post. The through hole 20 has a first diameter reduction part 21 reducing a diameter from an opening 20β toward an opening 20α at the one principal plane 11α in a partial area including the opening 20β of the other principal plane 11β of the through hole 20, the diameter of a part corresponding to the first diameter reduction part 21 of the electrode post 13 is smaller than the minimum inner diameter of the through hole of the first diameter reduction part 21, and the electrode post 13 and an inner circumferential surface of the through hole 20 are connected in an area other than the first diameter reduction part 21.

Description

  The present invention relates to a particle beam position detector.

In recent years, a device called a Micro PixelGas Chamber (micro pixel gas chamber) system (hereinafter also referred to as MPGC system) has been proposed as a device for measuring the position of a neutron incident in a measurement target space with high accuracy. . Patent Document 1 below discloses an example of this MPGC system. FIG. 4A is a schematic perspective view of the particle beam position detector 100 provided in the conventional MPGC system, and FIG. 4B is a schematic cross-sectional view of the conventional MPGC system. The MPGC system includes a particle beam position detector 100, a drift electrode 117, position detection signal lines 122 and 124 connected to the particle beam position detector 100, and a position detection electronic circuit (not shown).

  The particle beam position detector 100 has a first direction (FIG. 4A) on the insulating substrate 111 and one main surface of the insulating substrate 111 (the lower main surface in FIGS. 4A and 4B). A first electrode 112 elongated along a second direction (X direction in FIG. 4A) orthogonal to the first direction, arranged adjacent to each other along the Y direction in FIG. The second electrodes 114 that are long along the first direction and are arranged adjacent to each other along the second direction on the other main surface (the main surface on the upper side in the figure), and the first direction and the second direction The plurality of through holes 111A having openings on each of the one main surface and the other main surface of the insulating substrate 111 and the plurality of through holes 111A are arranged in a matrix along each of the plurality of through holes 111A. An electrode post 113 bonded to the peripheral surface and fixed in the through hole 111A. Eteiru. Each of the plurality of first electrodes 112 closes one main surface side opening of the plurality of through-holes 111A arranged in a line along the second direction, and one of the electrode posts 113 arranged in the closed through-hole 111A. When joined to the end on the main surface side, each of the plurality of second electrodes 114 includes a plurality of openings 116 arranged in a line along the first direction, and when viewed from the direction perpendicular to the other main surface Each of the plurality of openings 116 has an end portion on the other main surface side of the plurality of electrode posts 113 arranged in a line along the first direction.

  Above the other main surface of the insulating substrate 111, a drift electrode 117 is disposed at a predetermined interval from the other main surface. The drift electrode 117 and the insulating substrate 111 are disposed in a housing (not shown), and the space between the drift electrode 117 and the insulating substrate 111 is filled with a gas composed of argon, ethane, or the like. A space between the drift electrode 117 and the insulating substrate 111 is a measurement target space for specifying the incident position of the neutron beam. The second electrode 114 and the drift electrode 117 are set to the same negative potential (for example, −250 V), and the first electrode 112 and the electrode post 113 are set to the positive potential (for example, +250 V). The plurality of first electrodes 112 and the plurality of second electrodes 114 are respectively joined to individual signal lines 122 and 124, and the signal lines 122 and 124 are connected to an electronic circuit (not shown).

FIG. 4B also shows the operating state of the MPGC system. When neutrons enter the measurement target space between the drift electrode 117 and the insulating substrate 111, the electrons 130 are ionized from the gas molecules by colliding with the gas molecules. The electrons 130 ionized in the gas by the incident neutrons drift toward the electrode post 113 by the electric field (drift electric field) between the drift electrode plate 117 and the electrode post 113. In the vicinity of the electrode post 113, a high voltage of, for example, 500 V is applied between the electrode post 113 and the second electrode 114 disposed in the vicinity of the end face of the electrode post 113. The electrons 130 that have moved to the vicinity of the electrode post 113 by the drift electric field are accelerated by the strong electric field between the electrode post 113 and the second electrode 114 and collide with gas molecules, and further electrons 130 are ionized from the gas molecules. The so-called avalanche amplification occurs. The ionized electrons 130 finally reach the electrode post 113. In this avalanche amplification, positive ions 140 of gas molecules are generated in addition to electrons, and the generated positive ions 140 move quickly to the surrounding cathode electrode (second electrode 114). Thus, at the incident position of neutrons in the measurement target space, due to this gas avalanche amplification, both the electrode post 113 and the second electrode 114 are relatively large so that they can be observed on the electric circuit. Will be incident. An electrical signal corresponding to the charges incident on the electrode post 113 and the second electrode 114 is sent to the above-described electronic circuit (not shown) via the signal lines 122 and 124. The electronic circuit can detect the incident position of the neutron beam by specifying the electrode post 113 and the second electrode 114 on which the charge due to the electrons 130 and the positive ions 140 caused by the neutron beam is incident.

JP 2011-247602 A

  In such an MPGC system, in order to obtain a high gas amplification factor, it is necessary to apply a high voltage of about 500 V or more between the electrode post 113 and the second electrode 114 with a small interval of, for example, 50 μm or less. . In the conventional particle beam position detector, a large current flows between the electrode post 113 and the second electrode 114 via the surface of the insulating substrate 111 due to the high voltage, and the shape of the electrode changes due to heat generated by the current. Or the electrode itself may be disconnected. In addition, there is a problem that, for example, a piece of electrode sparked by heat due to a momentary large current adheres to the second electrode 114 on the surface of the insulating substrate 111, thereby causing a short circuit between two adjacent second electrodes 114. Sometimes occurred. The present invention has been made to solve such problems.

  The present invention relates to a ceramic substrate and a first electrode elongated along a second direction orthogonal to the first direction, arranged adjacent to each other along the first direction on one main surface of the ceramic substrate. A second electrode elongated along the first direction, arranged adjacent to each other along the second direction on the other main surface of the ceramic substrate, and the first direction and the second direction A plurality of through-holes having openings in each of the one main surface and the other main surface of the ceramic substrate and arranged in a matrix along the plurality of through-holes. An electrode post that is joined to a part of a peripheral surface and fixed in the through-hole, and each of the plurality of first electrodes is formed of the plurality of through-holes arranged in a line along the second direction. Meanwhile, the opening on the main surface side is closed and closed. The plurality of second electrodes are joined to end portions on the one main surface side of the electrode posts disposed in the through holes, and each of the plurality of second electrodes is arranged in a row along the first direction. When viewed from a direction perpendicular to the other main surface, each of the ends on the other main surface side of the plurality of electrode posts arranged in a line along the first direction in each of the plurality of openings. The plurality of through-holes are arranged in a part of the region including the opening on the other main surface side of the through-hole from the opening on the other main surface side. It has a first reduced diameter portion that is reduced in diameter toward the opening on the main surface side, and a diameter of a portion corresponding to the first reduced diameter portion of the electrode post is a minimum of the through hole in the first reduced diameter portion. Smaller than the inner diameter, in the region other than the first reduced diameter portion, the electrode post and the front To provide a particle beam position detector, characterized in that said inner peripheral surface of the through hole are joined.

  According to the particle beam position detector of the present invention, each of the plurality of through holes is formed in a partial region including the opening on the other main surface side of the through hole, from the opening on the other main surface side to the opening on the one main surface side. The diameter of the portion corresponding to the first reduced diameter portion of the electrode post is made smaller than the minimum inner diameter of the through hole in the first reduced diameter portion. Since the distance (creeping distance) along the surface of the ceramic substrate between the electrode disposed on the other main surface side and the electrode post disposed in the through hole is relatively long, between the electrode post and the electrode It is possible to suppress a large current from flowing along the surface of the ceramic substrate.

(A) is a schematic perspective view which shows the example of one Embodiment of the particle beam position detector of this invention, (b) is a schematic top view. It is a schematic sectional drawing which expands and shows a part of MPGC system comprised including the particle beam position detector shown in FIG. It is a schematic sectional drawing which expands and shows a part of MPGC system comprised including the particle beam position detector of embodiment different from FIG. (A) is a schematic perspective view of the particle beam position detector with which the conventional MPGC system is equipped, (b) is a schematic sectional drawing of the conventional MPGC system.

  Hereinafter, an embodiment of the particle beam position detector of the present invention will be described. FIG. 1A is a schematic perspective view of a particle beam position detector 10 which is an example of an embodiment of the particle beam position detector of the present invention, and FIG. 1B is a schematic top view of the particle beam position detector 10. It is. FIG. 2 is an enlarged schematic cross-sectional view showing a part of the MPGC system 1 configured to include the particle beam position detector 10 shown in FIG. The MPGC system 1 is a device for measuring the position of a neutron incident in a measurement target space with high accuracy.

The particle beam position detector 10 includes, for example, a ceramic substrate 11 mainly composed of alumina (Al ₂ O ₃ ) and having a thickness of about 0.2 mm to 0.6 mm, and a first main surface 11α of the ceramic substrate 11. A first electrode 12 elongated along a second direction (X direction in the drawing) perpendicular to the first direction, arranged adjacent to each other along the direction (Y direction in the drawing), and the other of the insulating substrate On the main surface 11β, adjacent to each other along the second direction, the second electrodes 14 elongated along the first direction, and arranged in a matrix along the first direction and the second direction And a plurality of through holes 20.

  The width along the second direction of the first electrode 12 and the width along the first direction of the second electrode 14 are, for example, 0.2 mm to 0.6 mm, and the interval between the first electrodes 12 and the second The distance between the electrodes 14 is about 0.05 mm.

  The through hole 20 includes an opening 20α provided on the one main surface 11α side and an opening 20β provided on the other main surface 11β side. The diameters of the opening 20α and the opening 20β are about 0.1 mm to 0.5 mm.

  In addition, an electrode post 13 that is inserted into each of the plurality of through holes 20 and joined to a part of the inner peripheral surface of each of the through holes 20 is fixed in the through hole 20. The electrode post 13 has the same height as the thickness of the ceramic substrate 11, and the height of the electrode post 13 is about 0.1 mm to 0.5 mm.

The electrode post 13 is a metal member made of gold (Au) or copper (Cu) and formed in advance before being placed in the through hole 20. The through hole 20 provided in the ceramic substrate 11 made of alumina, for example. Are joined to each other through a joining layer 40 (see FIG. 2). The bonding layer 40 is formed using a known metallization technique including, for example, an Ag—Cu—Ti brazing material and a Ni plating layer. In the present embodiment, the bonding layer 40 is formed only in a region corresponding to a second reduced diameter portion 22 described later.

  Each of the plurality of first electrodes 12 closes the opening 21α on the one main surface 11α side of the plurality of through holes 20 arranged in a line along the second direction, and the electrode posts 13 disposed in the closed through holes 20. Are joined to the end 13α on the one main surface 11α side. Each of the plurality of second electrodes 14 includes a plurality of openings 16 arranged in a line along the first direction. When viewed from the direction perpendicular to the other main surface 11β, each of the plurality of openings 16 has a first Each of the end portions 13β on the other main surface 11β side of the plurality of electrode posts 13 arranged in a line along the direction is arranged. The through hole 20 and the opening 13 have the same central axis, and the diameter of the opening 13 is about 0.01 to 0.05 mm larger than the diameters of the openings 20α and 20β of the through hole 20. A plurality of through-holes 20 and openings 13 are arranged in a matrix along the first direction and the second direction with the interval between the central axes being about 0.3 mm to 0.5 mm.

  In the MPGC system 1, a drift electrode 17 is disposed above the other main surface 11β of the ceramic substrate 11 with a predetermined distance from the other main surface 11β. The drift electrode 17 and the insulating substrate 11 are disposed in a housing (not shown), and the space between the drift electrode 17 and the insulating substrate 11 is filled with a gas composed of argon, ethane, or the like. A space between the drift electrode 17 and the insulating substrate 11 is a measurement target space for specifying the incident position of the neutron beam. What is necessary is just to set suitably the number of the arrangement | sequence of the through-hole 20 and the opening 13 according to the magnitude | size of measurement object space.

  The second electrode 14 and the drift electrode 17 are set to the same negative potential (for example, −250 V), and the first electrode 12 and the electrode post 13 are set to the positive potential (for example, +250 V). The plurality of first electrodes 12 and the plurality of second electrodes 14 are respectively joined to individual signal lines 32 and 34, and the signal lines 32 and 34 are connected to an electronic circuit (not shown).

When neutrons enter the measurement target space between the drift electrode 17 and the insulating substrate 11, electrons e ⁻ (not shown) are ionized from the gas molecules by the neutrons. Electrons e ⁻ ionized in the gas by incident neutrons drift toward the electrode post 13 by an electric field (drift electric field) between the drift electrode plate 17 and the electrode post 13. In the vicinity of the electrode post 13, a high voltage of, for example, 500 V is applied between the electrode post 13 and the second electrode 14 disposed close to the end face of the electrode post 13. Electrons e ⁻ that have moved to the vicinity of the electrode post 13 by the drift electric field are accelerated by a strong electric field between the electrode post 13 and the second electrode 114 and collide with gas molecules, causing so-called avalanche amplification. . As a result, cations of gas molecules are generated in addition to electrons, and the generated cations move quickly to the surrounding cathode electrode (second electrode 14). Thus, at the neutron incident position in the measurement target space, due to this avalanche amplification, both the electrode post 13 and the second electrode 14 can be observed in a relatively large amount on the electric circuit. Charges are incident. An electrical signal corresponding to the charge incident on the electrode post 13 and the second electrode 14 reaches the above-described electronic circuit (not shown) via the signal lines 32 and 34. This electronic circuit (not shown) can identify the incident position of the neutron in the measurement target space by specifying the electrode post 13 and the second electrode 14 to which the charge caused by the electron e ⁻ caused by the neutron beam is incident. .

In the particle beam position detector 10 of the present embodiment, each of the plurality of through-holes 20 is arranged in a partial region including the opening 20β on the other main surface 11β side of the through-hole 20 from the opening 20β on the other main surface 11β side. It has a first reduced diameter portion 21 that is reduced in diameter toward the opening 20β on the main surface 11α side. In addition, the diameter of the portion corresponding to the first reduced diameter portion 21 of the electrode post 13 is smaller than the minimum inner diameter of the through hole 20 in the first reduced diameter portion 21, and a region other than the first reduced diameter portion 21. , The electrode post 13 and the inner peripheral surface of the through hole 20 are joined.

  The first reduced diameter portion 21 extends, for example, from the other main surface 11β side of the ceramic substrate 11 to an intermediate portion of the thickness of the ceramic substrate 11. In the present embodiment, the first reduced diameter portion 21 is arranged from the other main surface 11β side of the ceramic substrate 11 to the middle of the thickness of the ceramic substrate 11, and from the one main surface 11α side of the ceramic substrate 11, the ceramic substrate The second reduced diameter portion 22 is arranged up to the middle of the 11th thickness. For example, in the present embodiment in which the thickness of the ceramic substrate 11 is about 0.1 mm to 0.6 mm, the thickness of the first reduced diameter portion 21 and the thickness of the second reduced diameter portion 22 are about 0.05 to respectively. 0.3 mm. Although the minimum of the magnitude | size of the minimum internal diameter of the through-hole 20 in the 1st reduced diameter part 21 is not specifically limited, For example, it is about 0.01-0.05 mm small with respect to the diameter of opening 20 (beta). In the present embodiment, the size of the minimum inner diameter of the through hole 20 is set to a range of about 0.1 mm to 0.45 mm.

  The through-hole 20 described above is subjected to masking on the respective surfaces on the one main surface 11α side and the other main surface 11β side so that, for example, the opening 20α and the ceramic substrate 11 in the opening 20β are exposed, and then collides with alumina fine particles. Thus, it may be formed by a sandblasting method in which the exposed portion of the ceramic substrate 11 is shaved. In the sandblasting method, the machining diameter tends to decrease as the machining depth increases, and the second diameter-reduced portion 22 is processed in the machining from the main surface 11α side, and the first in the machining from the other main surface 11β side. A reduced diameter portion 21 is formed.

  As described above, each of the plurality of second electrodes 14 includes the plurality of openings 16 that overlap with the plurality of through holes 20 arranged in a line along the first direction, and is viewed from the direction perpendicular to the other main surface 11β. The openings 20β on the other main surface side of the plurality of through-holes 20 arranged in a line along the first direction and the end portions 13β on the other main surface 11β side of the electrode posts 13 in the openings 16 respectively. Each is arranged. The shortest spatial distance between the second electrode 14 and the electrode post 13 is the distance indicated by A in FIG. 2, but in this example, the opening 20β on the other main surface 11β side is changed to the opening 20β on the one main surface 11α side. The diameter of the portion corresponding to the first reduced diameter portion 21 of the electrode post 13 is smaller than the first reduced diameter portion 21, and the region other than the first reduced diameter portion 21. In the present embodiment (only the second reduced diameter portion 22 described later), the electrode post 13 and the inner peripheral surface of the through hole 20 are joined, so the so-called creepage distance along the surface of the ceramic substrate 11 is The distance is indicated by B in FIG.

  The first reduced diameter portion 21 has a height in the direction perpendicular to the other main surface 20β of about half the thickness of the ceramic substrate 11. The height of the first reduced diameter portion 21 is about 0.1 to 0.3 mm. The height of the second reduced diameter portion 22 in the direction perpendicular to the one main surface 20α is also about half the thickness of the ceramic substrate 11, and the height of the second reduced diameter portion 22 is about 0.1 to 0.1. 0.3 mm. The minimum inner diameter of the through hole 20 in the first reduced diameter portion 21 is smaller by about 0.2 to 0.7 mm than the diameter of the opening 20α. The minimum inner diameter of the first reduced diameter portion 21 is, for example, about 0.5 mm smaller than the opening 20α. The creepage distance B is, for example, about 0.1 to 0.3 mm.

  In the present invention, by increasing the creepage distance along the surface of the ceramic substrate 11, the generation of a large current along the surface of the ceramic substrate 11 is suppressed, and this is caused by the large current along the surface of the ceramic substrate 11. Deterioration of the second electrode 14 and the electrode post 13 is suppressed.

The through hole 20 is reduced in diameter in a part of the through hole 20 including the opening 20α on the one main surface 11α side from the opening 20α on the one main surface 11α side toward the opening 20β on the other main surface 11β side. A second reduced diameter portion 22 is provided. In addition, the electrode post 13 includes a positioning base portion 31 having a diameter portion smaller than the diameter of the opening 20α on the one main surface 11α side of the through hole 20 and larger than the minimum inner diameter of the second reduced diameter portion 22; A protrusion 32 protruding from the positioning base 31 and having a minimum inner diameter in the second reduced diameter portion 22 and a diameter smaller than the minimum inner diameter in the first reduced diameter portion 21 is provided. In the particle beam position detector 10, a part of the positioning base portion 31 is in contact with the inner peripheral surface of the second reduced diameter portion 22, and the protruding portion 32 is disposed on the first reduced diameter portion 21. In this state, the peripheral surface of the positioning base portion 31 and the inner peripheral surface of the second reduced diameter portion 22 are joined via the joining member 40.

  The second reduced diameter portion 22 is reduced in diameter from the opening 20α on the one main surface 11α side toward the opening 20β on the other main surface 11β side, and a part of the outer peripheral surface of the positioning base portion 31 is the second reduced diameter portion. The position of the positioning base portion 31 with respect to the through hole 20 is determined by contacting the diameter portion 22. In the embodiment shown in FIG. 2, a part of the outer peripheral surface of the positioning base portion 31 has a shape corresponding to a part of the second reduced diameter portion 22 of the through hole 20. The position of the positioning base portion 31 with respect to the through hole 20 is determined by a part of the peripheral surface and a part of the inner surface of the second reduced diameter portion 22 abutting each other. When the first reduced diameter portion 21 is provided and the diameter of a part of the electrode post 13 is reduced, the inner peripheral surface of the first reduced diameter portion 21 and the electrode post 13 are separated from each other. The position of the electrode post 13 cannot be defined by the inner peripheral surface of the first reduced diameter portion 21. However, by providing the second diameter-reduced portion 22 and providing the positioning base portion 31 in a part of the electrode post 13, the electrode post can be opened from the opening 20α having a relatively large diameter with respect to the positioning base portion 31. 13 can be easily inserted into the through hole 20, and the position of the electrode post 13 with respect to the through hole 20 is defined with high accuracy while the inner peripheral surface of the first reduced diameter portion 21 and the electrode post 13 are separated. can do. The diameter of the cross section of the positioning base portion is 0.1 to 0.5 mm, and the diameter of the protruding portion 22 is about 0.05 to 0.2 mm smaller than the minimum inner diameter of the first reduced diameter portion 21. .

  In the embodiment shown in FIG. 2, a part of the outer peripheral surface of the positioning base portion 31 has a shape corresponding to a part of the second reduced diameter portion 22 of the through hole 20, but the embodiment shown in FIG. As described above, the positioning base 31 may be formed in a columnar shape having a certain diameter. Also in this case, the inside of the through hole 20 is in a state in which the peripheral line on the upper surface of the positioning base portion 31 is in contact with the position of the second reduced diameter portion 22 having a diameter (inner peripheral diameter) corresponding to this constant diameter. The electrode post 13 is positioned and fixed to the surface. The shape of the through hole 20 and the shape of the electrode post 13 are not particularly limited.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to the above-mentioned various embodiment, In the range which does not deviate from the summary of this invention, it is possible to perform various improvements and changes. Of course.

10 Particle beam position detector 11 Ceramic substrate 11α One main surface 11β Other main surface 12 First electrode 13 Electrode post 14 Second electrode 16 Opening 17 Drift electrode 20 Through-hole 20α, 20β Opening 21 First reduced diameter portion 22 Second Reduced diameter part 31 Positioning base part 40 Bonding layer

Claims (2)

A ceramic substrate;
A first electrode elongated along a second direction orthogonal to the first direction, arranged adjacent to each other along the first direction on one main surface of the ceramic substrate;
A second electrode elongated along the first direction, arranged adjacent to each other along the second direction on the other main surface of the ceramic substrate;
A plurality of through holes arranged in a matrix along the first direction and the second direction, each having an opening on each of the one main surface and the other main surface of the ceramic substrate;
An electrode post that is inserted into each of the plurality of through holes, joined to a part of the inner peripheral surface of each of the through holes, and fixed in the through hole;
Each of the plurality of first electrodes closes the openings on the one main surface side of the plurality of through holes arranged in a line along the second direction, and the electrode posts disposed in the closed through holes Are joined to the end of the one main surface side of
Each of the plurality of second electrodes includes a plurality of openings arranged in a line along the first direction,
When viewed from a direction perpendicular to the other main surface, each of the plurality of openings is provided with an end on the other main surface side of the plurality of electrode posts arranged in a line along the first direction. A particle beam position detector,
Each of the plurality of through holes has a first diameter that is reduced in diameter from the opening on the other main surface side toward the opening on the one main surface side in a partial region including the opening on the other main surface side of the through hole. A diameter of a portion corresponding to the first reduced diameter portion of the electrode post having a reduced diameter portion is smaller than a minimum inner diameter of the through hole in the first reduced diameter portion, and a region other than the first reduced diameter portion. The particle beam position detector according to claim 1, wherein the electrode post and the inner peripheral surface of the through hole are joined. The through hole has a second reduced diameter portion that is reduced in diameter from the opening on the one main surface side toward the opening on the other main surface side in a partial region including the opening on the one main surface side of the through hole. Have
The electrode post is
A positioning base portion having a diameter portion smaller than the diameter of the opening on the one main surface side of the through hole and larger than the minimum inner diameter of the second reduced diameter portion;
A minimum diameter portion protruding from the positioning base portion, having a minimum inner diameter in the second reduced diameter portion, and a smaller diameter portion having a diameter smaller than the minimum inner diameter in the first reduced diameter portion,
At least a part of the positioning base part is in contact with an inner surface of the second reduced diameter part, and at least a part of the protruding part is disposed on the first reduced diameter part. The particle beam position detector according to claim 1, wherein a part and at least a part of an inner peripheral surface of the second reduced diameter part are joined.

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