JPH08194065A - Proportional counter tube - Google Patents

Abstract

PURPOSE: To provide a proportional counter tube provided with a beryllium window joined to an outer tube with a silver solder having little deformation by supporting a beryllium film which is softened at soldering with the silver solder by a reinforcing member at the exhaust of the outer tube. CONSTITUTION: An outer tube 10 is provided with a beryllium window 30, a reinforcing member 40, and a linear anode 50. The outer tube 10 is composed of an almost cylindrical tubular wall 11 and flanges 12 and an open part 20 through which radiant rays to be detected enter is formed in the tubular wall 11. The flanges 12 are made of an insulator and insulate the outer tube 10 which works as a cathode and the anode 50 while keeping air-tightness of a proportional counter tube. As for the window 30, a Be thin film covers the member 40 and the open part 20. Moreover, the window 30 is jointed to the tubular wall 11 with a silver solder and consequently, the window 30 is electrically connected with the tubular wall 11, that is a cathode. The member 40 is set between the window 30 and the open part 20 and supports the window 30 and joined to the tubular wall 11 and the window 30 with the silver solder.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a proportional counter for detecting radiation.

[0002]

2. Description of the Related Art FIG. 8 is a diagram showing the structure of a conventional proportional counter. This is a horizontal (side-on) proportional counter, and is provided with an envelope 10, a beryllium (Be) window 30, and an anode 50 for taking out signals. The outer tube 10 is composed of a substantially cylindrical tube wall 11 and flanges 12 provided at both ends of the tube wall 11. An opening 20 for incidence of radiation is formed on the tube wall 11. The tube wall 11 serves as a cathode when the proportional counter operates. The flange 12 is made of an insulating material and insulates the anode 50 from the envelope tube 10 serving as a cathode while maintaining the airtightness of the proportional counter. Be
The window 30 is a thin film that covers the radiation entrance 20. Be is a radiation transparent material, and the inside of the proportional counter is blocked from the outside while the radiation of the radiation into the proportional counter is maintained by the Be window 30. As a result, the airtightness of the proportional counter is maintained.

Generally, the Be window 30 and the tube wall 11 are joined by a diffusion joining method, an ion beam joining method, an organic adhesive, a brazing material, or the like. However, Be having a curved surface as in the proportional counter of FIG.
It is difficult to apply the diffusion bonding method to the window 30. Further, the ion beam bonding method is not suitable for a general production line because it is difficult to set conditions according to the thin Be window 30 and large-scale equipment is required. In addition, joining with an organic adhesive is not suitable for automation and mass production of proportional counters because of the inconvenience of joining work. Furthermore, when the Be window 30 is joined by using the joining technique using the organic adhesive, the outer tube 10 cannot be kept in a sufficiently high temperature state when the outer tube 10 is exhausted in the manufacturing process of the proportional counter. However, there is a possibility that the impure gas inside the pipe may be released after manufacturing. Since this influence depends on the ambient temperature of the proportional counter, the handling of the proportional counter becomes difficult.

On the other hand, the joining method using a high-temperature brazing material such as silver brazing material is suitable for mass production of proportional counters, which allows work to be performed with simple equipment and simple condition setting. Since exhaust can be sufficiently performed, there is an advantage that a highly reliable proportional counter can be provided.

[0005]

Problems to be Solved by the Invention
When the window 30 is bonded to the tube wall 11, the Be window 30 is heated, so that Be is recrystallized and softened, so that the Be window 30 is melted.
Strength decreases. As a result, the Be window 30 is deformed as shown in FIG. 9 due to the pressure difference between the inside and the outside of the outer tube 10 when the outer tube 10 is exhausted.

The proportional counter having the modified Be window 30 has the following problems.

Since the Be window 30 is deformed, air leakage occurs. As a result, the airtightness essential for maintaining the performance of the proportional counter is impaired.

When the Be window 30 serves as a cathode,
When a part of the Be window 30 is dented inward from the inner peripheral surface of the tube wall 11 which is the cathode like the Be window 30 due to the deformation, the electric field is disturbed inside the proportional counter, and the original performance of the proportional counter is exhibited. It will not be done.

The thinner the Be window, the greater the deformation thereof, and the above-mentioned problems become more remarkable. However, today
The demands of industry such as detection of sulfur content in petroleum are suitable for higher sensitivity detection and lower energy element detection.
In response to this, the tendency toward thinning of the Be window is increasing. Therefore, there is a great demand for realizing a proportional counter including a Be window joined by silver brazing and having a small deformation.

An X-ray irradiating device which prevents cracks and the like in an X-ray emitting window made of Be caused by strain due to its own tension is disclosed in Japanese Patent Laid-Open No. 5-67560, but silver between the Be window and the tube wall is disclosed. Proportional counters that prevent Be window deformation due to brazing have not been realized yet.

The present invention has been made in order to meet the above-mentioned demands, and an object of the present invention is to provide a proportional counter having a beryllium window joined to an outer tube with silver brazing and having a small deformation.

[0012]

In order to solve the above-mentioned problems, the proportional counter of the present invention has an outer tube having an opening formed in the wall of the tube into which radiation to be detected is incident, and an outer tube. The beryllium film that covers the opening of the bezel and is joined to the envelope by silver brazing, and the reinforcement that is placed between the beryllium film and the opening of the envelope and that is joined to the envelope and the beryllium film by silver brazing. A member and an electrode penetrating the envelope are provided.

The peripheral portion of the reinforcing member is embedded in a recess provided in a portion of the pipe wall that is located around the opening and includes the outer surface of the pipe wall, and the surface of the reinforcing member is substantially flat with the outer surface of the pipe wall. It is better to form a rough surface. Further, the beryllium film may cover the reinforcing member. Further, it is preferable that the portion of the reinforcing member located above the opening of the envelope has a lattice shape.

[0014]

In the proportional counter of the present invention, since the reinforcing member is installed between the opening provided in the wall of the tube and the beryllium film, the beryllium film softened at the time of the silver brazing joining with the envelope tube is performed. Even if pressure is applied during exhaust of the envelope, the beryllium film is supported by the reinforcing member, so that the beryllium film is hardly deformed. Therefore, the proportional counter of the present invention has good airtightness and high reliability and operates well without disturbance of the electric field in the tube even when the beryllium film functions as a cathode.

In the proportional counter of the present invention in which the peripheral portion of the reinforcing member is embedded in the recess of the pipe wall, the surface of the reinforcing member and the outer surface of the pipe wall form a substantially flat surface, Since the beryllium film is bonded on this flat surface via the silver solder, the bonding state becomes extremely good. Therefore, this type of proportional counter has better air tightness and higher reliability.

When the beryllium film covers the reinforcing member,
Since the peripheral portion of the beryllium film is bonded to the tube wall via the silver solder, the beryllium film and the tube wall are strongly bonded. As a result, a more reliable proportional counter is realized.

[0017]

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements will be denoted by the same reference symbols, without redundant description.

Embodiment 1 FIG. 1 is a side sectional view of a proportional counter of this embodiment. The proportional counter is of a horizontal type (side-on type), and includes an envelope 10, a beryllium (Be) window 30, a reinforcing member 40, and a linear anode 50. The tube is filled with a gas in which a small amount of ionized gas such as Ne or Ar is mixed with CH ₄ or CO ₂ as a quenching gas.

The outer tube 10 is made of stainless steel (SUS) and serves as a cathode when the proportional counter operates. The outer tube 10 includes a substantially cylindrical tube wall 11 and a tube wall 1.
It is composed of flanges 12 installed at both ends of 1. An opening (radiation entrance) 20 through which the radiation to be detected enters is formed in the tube wall 11. The flange 12 is made of an insulating material (in this embodiment, Kovar glass), and insulates the anode 50 from the envelope tube 10 serving as a cathode while maintaining the airtightness of the proportional counter.

The anode 50 is a Pt wire having a uniform thickness and a smooth surface, and penetrates the envelope 10 from the flange 12 at one end of the envelope 10 to the flange 12 at the other end. During operation of the proportional counter, a positive voltage is applied to the anode 50, and a signal corresponding to the energy and dose of radiation is extracted from the anode 50.

The Be window 30 is a Be thin film of about 50 μm, and covers the reinforcing member 40 and the radiation entrance 20. Be is a radiation transmitting material. Therefore, the Be window 30 keeps the transmission of radiation into the proportional counter inside, while the inside of the proportional counter is blocked from the outside, and the airtightness of the proportional counter is maintained. ing.

Further, the Be window 30 is made of silver braze to form the pipe wall 1.
1, the Be window 30 is electrically connected to the tube wall 11, that is, the cathode. Therefore, the Be window 30 becomes a cathode like the tube wall 11 when the proportional counter operates.

As described above, the proportional counter of this embodiment is Be
Since the window 30 is joined to the envelope 10 by silver solder, it has an advantage that mass production is easy.

The reinforcing member 40 is arranged between the Be window 30 and the radiation entrance 20 and supports the Be window 30.
This reinforcing member 40 is made of silver brazing so that
It is joined to the window 30.

FIG. 2 is a plan view showing the reinforcing member 40. As shown in FIG. 2, the reinforcing member 40 has a lattice shape, and its peripheral edge is a frame portion 41 wider than other portions. In the proportional counter of the present embodiment, this frame portion 41
Are fixed on the tube wall 11 around the radiation entrance 20. During operation of the proportional counter, the radiation that has passed through the Be window 30 will pass through the gaps in the lattice of the reinforcing member 40 and enter the tube, so that the reinforcing member 40 will be placed between the Be window 30 and the radiation entrance 20. It is possible to detect radiation sufficiently satisfactorily even if it is interposed in the.

In this embodiment, the reinforcing member 40 is the outer tube 10.
It is made of the same stainless steel (SUS) material as.
Since the reinforcing member 40 is electrically connected to the tube wall 11 by silver brazing, the reinforcing member 40 also serves as a cathode like the Be window 30 when the proportional counter operates.

FIG. 3 shows Be of the proportional counter of this embodiment.
FIG. 6 is an enlarged cross-sectional view showing a joint portion between the window 30 and the reinforcing member 40 and the tube wall 11. The frame 41 of the reinforcing member 40 is arranged on the tube wall 11 located around the radiation entrance 20, and the peripheral edge of the Be window 30 is arranged on the frame wall 41 with the silver brazing material 90 interposed therebetween. As shown in FIG. 3, the silver brazing material 90 covers the frame portion 41 while being interposed between the peripheral edge portion of the Be window 30 and the frame portion 41 of the reinforcing member 40, and is also in contact with the pipe wall 11. Thereby, the Be window 30 and the reinforcing member 40 are fixed to the pipe wall 11.

As shown in FIG. 3, since the reinforcing member 40 supports the Be window 30 on the radiation entrance 20, B generated when the envelope 10 is evacuated in the manufacturing process of the proportional counter.
e The deformation of the window 30 is reduced. In particular, the depression reaching the inside of the tube wall 11 as shown in FIG. 9 does not occur. For this reason, the proportional counter of this embodiment has less air leakage than the conventional one, has good airtightness and high reliability, and operates well without any disturbance of the electric field in the tube during operation.

Further, in this embodiment, the Be window 30 has a larger area than the reinforcing member 40 and covers the reinforcing member 40. As a result, the end portion of the Be window 30 is joined to the pipe wall 11 without sandwiching the frame portion 41 with the pipe wall 11, so that the frame portion is provided between the other portion of the Be window 30 and the pipe wall 11. Even if 41 is interposed, the bond will be strong.

Embodiment 2 FIG. 4 is a side sectional view of the proportional counter of this embodiment. The proportional counter of this embodiment has a radiation entrance 20 on the tube wall 11.
The present embodiment is different from the first embodiment in that the frame portion 41 of the reinforcing member 40 is embedded in the concave portion 15 that is provided around the periphery of the pipe wall 11 and that includes the outer surface of the pipe wall 11.

FIG. 5 shows Be of the proportional counter of this embodiment.
FIG. 6 is an enlarged cross-sectional view showing a joint portion between the window 30 and the reinforcing member 40 and the tube wall 11. The recess 15 is the frame portion 4 of the reinforcing member 40.
When the frame portion 41 is embedded in the recess 15, the outer surface of the pipe wall 11 and the surface of the frame portion 41 form a substantially flat surface.

As in the first embodiment, since the reinforcing member 40 supports the Be window 30, the Be generated when the envelope 10 is evacuated.
The deformation of the window 30 is reduced. Further, the Be window 30 covers the reinforcing member 40, and since the end portion of the Be window 30 is joined to the pipe wall 11 without sandwiching the frame portion 41 between the Be window 30 and the pipe wall 11, a strong joint is formed. ing. Therefore, the proportional counter according to the present embodiment also has a small air leakage, has good airtightness and high reliability, and operates well without any disturbance of the electric field in the tube during operation.

Further, the proportional counter of the present embodiment has a tube wall 11
Since the Be window 30 and the tube wall 11 are joined to each other by the silver braze existing on the flat surface formed by the frame portion 41, extremely good joining is realized.

As compared with the proportional counter of Example 1, FIG.
In the proportional counter of the first embodiment, as shown in FIG.
1 is placed on the pipe wall 11, the frame portion 41 is
Raised on the outer surface of 1. Therefore, cracks (100 in FIG. 3) are likely to occur in the vicinity of the frame portion 41 due to the protrusion, and the airtightness of the proportional counter may be reduced.

On the other hand, in the proportional number tube of this embodiment,
Since the Be window 30 and the tube wall 11 are joined by the presence of the silver solder 90 on the flat surface composed of the outer surface of the tube wall 11 and the surface of the frame section 41, a crack occurs near the frame section 41. It gets harder. Further, since the silver brazing material 90 exists substantially evenly between the Be window 30 and the tube wall 11 and the frame portion 41, good joining is realized. From the above, the proportional counter of this embodiment has extremely good airtightness and high reliability.

Next, regarding the proportional counter of the second embodiment, a method of attaching the reinforcing member 40 and the Be window 30 to the tube wall 11 will be described. 6 and 7 illustrate this mounting method. In addition, also in the proportional counter of Example 1, the reinforcing member 40 and the Be window 30 are attached to the tube wall 11 by the same method.

First, as a preparation for silver brazing, as shown in FIG. 6, a Ti layer 81 of about 3000 angstrom is vapor-deposited on the brazing portion of the Be window 30 (FIG. 6 (a)) (see FIG. b)), and then a Cu layer 82 of about 3000 angstrom is deposited (FIG. 6C).

The Cu layer 82 enhances the wettability of the silver solder to Be so that the silver solder easily fits into the Be window 30. However, Be is likely to combine with Cu to form a Cu-Be alloy, and especially when a thin Be film having a thickness of 100 μm or less as in this embodiment is an alloy, the Be window 30 is very easily cracked and the proportional counter tube is formed. It becomes a problem in the vacuum resistance characteristic.
Therefore, in this embodiment, the Ti layer 81, which is well compatible with Be and is difficult to alloy with Be, is formed on the Be window 3 before the deposition of the Cu layer 82.
The Cu layer 82, which is well compatible with silver brazing, is vapor-deposited at the brazing point of 0.

On the other hand, since SUS, which is the material of the tube wall 11, does not have good wettability of silver braze, as shown in FIG. 7, the brazing portion of the tube wall 11 is Ni which is well compatible with both SUS and Be. The layer 83 is vapor-deposited in advance. If the Ni layer 83 is too thick, it will be easily peeled off.
The thickness was controlled to 0 angstrom.

After the above preparation, silver brazing is carried out. In this embodiment, BAg-8 (JIS standard product) is used as the silver solder. This has a composition of Ag 72%, Cu 28%, and other components of 0.15% or less.

As shown in FIG. 7, the reinforcing member 40, the silver brazing sheet 91, and the Be window 30 are installed in this order in the recess 15 of the tube wall 11 and then heated in a vacuum to form the silver brazing sheet 91. Melt. The silver brazing sheet 91 is a thin film of silver brazing material having substantially the same shape as the frame portion 41 of the reinforcing member 40. The heating temperature is set between about 600 and 900 ° C., but in this embodiment, the silver brazing sheet 91 was kept at about 780 ° C. and kept for 1 minute. The thus-melted silver solder comes to be interposed between the Be window 30 and the tube wall 11 and the reinforcing member 40 as shown in FIG. After that, when gradually cooled, the silver brazing solidifies, and the Be window 30 and the reinforcing member 40 are joined to the tube wall 11.

In the case of the proportional counter of Example 1, since the recess 15 is not present in the tube wall 11, the reinforcing member 40, the silver brazing sheet 91, and the Be window 30 are sequentially mounted on the flat surface of the tube wall 11. After placing, heat treatment will be performed.

The present invention is not limited to the above embodiment, but various modifications can be made. For example, the proportional counter of the present invention may be a vertical type (head-on type) as well as the horizontal type as in the present embodiment.

[0044]

As described above in detail, according to the present invention, the beryllium film softened during the silver brazing is supported by the reinforcing member when the envelope is evacuated. A proportional counter with a bonded low deformation beryllium window is realized. Therefore, the proportional counter of the present invention has good hermeticity and high reliability, and also works well when the beryllium window functions as a cathode.

In the proportional counter of the present invention in which the peripheral portion of the reinforcing member is embedded in the recess of the pipe wall, silver brazing is provided on the flat surface formed by the surface of the reinforcing member and the outer surface of the pipe wall. Since the beryllium film is bonded to the beryllium film, the condition of the bonding is very good, and therefore, this type of proportional counter has better airtightness and higher reliability.

In the proportional counter of the present invention in which the beryllium film covers the reinforcing member, since the peripheral portion of the beryllium film is joined to the pipe wall via silver brazing, the beryllium film and the pipe wall are joined together. The joint is strong. Therefore, this type of proportional counter is more reliable.

[Brief description of drawings]

FIG. 1 is a side sectional view of a proportional counter according to a first embodiment.

FIG. 2 is a plan view showing a reinforcing member.

FIG. 3 is an enlarged cross-sectional view showing a Be window and a joining portion of a reinforcing member and a tube wall in the proportional counter of Example 1.

FIG. 4 is a side sectional view of a proportional counter according to a second embodiment.

FIG. 5 is an enlarged cross-sectional view showing a Be window and a joining portion of a reinforcing member and a tube wall in the proportional counter of Example 2;

FIG. 6 is a diagram showing vapor deposition of a Ti layer and a Cu layer on a Be window.

FIG. 7 is a diagram showing a method of attaching a Be window and a reinforcing member to an outer envelope.

FIG. 8 is a partial sectional view showing a conventional proportional counter.

FIG. 9 is an enlarged cross-sectional view showing a joint portion of a Be window and a tube wall in a conventional proportional counter.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Surrounding tube, 11 ... Tube wall, 12 ... Flange, 20 ... Radiation entrance, 30 ... Beryllium window, 40 ... Reinforcing member, 5
0 ... Anode.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuhiko Ikeda 1126 No. 1126 Nomachi, Hamamatsu City, Shizuoka Prefecture Hamamatsu Photonics Co., Ltd.

Claims (4)

[Claims] 1. An outer envelope having an opening formed on a wall of a tube to which radiation to be detected is incident, and a beryllium film that covers the opening of the outer envelope and is joined to the outer envelope by silver solder. A proportional counter comprising: a reinforcing member that is disposed between the beryllium film and the opening and is joined to the envelope and the beryllium film by silver brazing; and an electrode that penetrates the envelope. 2. A peripheral portion of the reinforcing member is embedded in a recess provided in a portion of the pipe wall around the opening and including an outer surface of the pipe wall, and the surface of the reinforcing member is The proportional counter according to claim 1, wherein a surface that is substantially flat with the outer surface of the tube wall is formed. 3. The proportional counter according to claim 1, wherein the beryllium film covers the reinforcing member. 4. The portion of the reinforcing member located above the opening has a lattice shape.
3. The proportional counter according to any one of 3 above.