WO2016140112A1

WO2016140112A1 - Geiger-müller counter and radiation measuring meter

Info

Publication number: WO2016140112A1
Application number: PCT/JP2016/055323
Authority: WO
Inventors: 竹内敏晃; 濱口邦夫; 福島孝晴; 木村悟利
Original assignee: 日本電波工業株式会社
Priority date: 2015-03-04
Filing date: 2016-02-24
Publication date: 2016-09-09
Also published as: JP2016161468A

Abstract

The objective of the present invention is to provide a Geiger-Müller counter and a radiation measuring meter with which stable radiation measurement can be performed, and having a high β-ray measuring sensitivity. This Geiger-Müller counter (100) is provided with: an enclosed tube (110) having a hermetically sealed space; an anode (120) which is disposed inside the space and is formed in the shape of a flat plate; a cathode (130) which is formed in the shape of a flat plate and is disposed inside the space, parallel to the anode, a prescribed distance from the anode; and an inert gas and a quenching gas which are hermetically sealed inside the space.

Description

Geiger-Muller counter and radiation meter

The present invention relates to a Geiger-Muller counter having a flat cathode electrode and an anode electrode and a radiation measuring instrument.

The Geiger-Muller counter (GM tube) is a component mainly used for radiation measurement. The GM tube is formed, for example, by placing an anode electrode and a cathode electrode in an enclosed tube such as a glass tube and enclosing an inert gas or the like. The GM tube is used by applying a high voltage between the anode electrode and the cathode electrode. The radiation that has entered the sealed tube ionizes the inert gas into electrons and ions, and the ionized electrons and ions are accelerated toward the anode electrode and the cathode electrode, respectively. This energizes between the anode electrode and the cathode electrode to generate a pulse signal. For example, Patent Document 1 discloses a GM tube including a rod-shaped anode electrode and a cylindrical cathode electrode surrounding the anode electrode and formed of a metal sheet.

JP 2014-55817 A

However, in Patent Document 1, since the cylindrical cathode electrode formed of a metal sheet blocks β-rays having no transmission power, the detection sensitivity of β-rays is low. Further, there is an electric field intensity attenuation around the rod-shaped anode electrode depending on the distance from the anode electrode, and the measurement sensitivity is likely to fluctuate and the measurement result may become unstable.

An object of the present invention is to provide a Geiger-Muller counter and a radiation meter that can perform stable radiation measurement and have high β-ray measurement sensitivity.

A Geiger-Muller counter tube according to a first aspect is a sealed tube having a sealed space, an anode electrode disposed in the space and formed in a flat plate shape, formed in a flat plate shape, and parallel to the anode electrode in the space, A cathode electrode disposed at a predetermined interval from the anode electrode; and an inert gas and a quench gas sealed in the space.

In the Geiger-Muller counter tube according to the second aspect, in the first aspect, at least one of the anode electrode and the cathode electrode is formed of a metal mesh in which a plurality of metal wires are knitted in a net shape.

In the Geiger-Muller counter tube according to the third aspect, in the first aspect, at least one of the anode electrode and the cathode electrode is formed of a metal plate.

In the Geiger-Muller counter tube according to the fourth aspect, in the third aspect, the metal plate is formed with a plurality of through holes penetrating the metal plate.

In the Geiger-Muller counter tube according to the fifth aspect, in the first aspect, at least one of the anode electrode and the cathode electrode is formed into a flat plate shape by bending one metal wire.

A Geiger-Muller counter tube according to a sixth aspect is the first to fifth aspects of the Geiger-Muller counter tube, in which the cathode electrode is composed of two plate-like electrodes parallel to each other, and the anode electrode is sandwiched between the two plate-like electrodes. It is.

A Geiger-Muller counter tube according to a seventh aspect is the first to fifth aspects, wherein the anode electrode is composed of a plurality of flat electrodes, the cathode electrode is composed of a plurality of flat electrodes, And the flat electrodes of the cathode electrode are arranged so as to alternately overlap each other.

The Geiger-Muller counter tube according to an eighth aspect is the first to seventh aspects, wherein the space includes a first electrode pair formed by an anode electrode and a cathode electrode and fixed to one end of the enclosing tube, and a first electrode pair. And a second electrode pair fixed to the other end of the sealed tube, and the first electrode pair and the second electrode pair are arranged on the same plane.

A Geiger-Muller counter tube according to a ninth aspect includes a shielding portion that surrounds the first electrode pair from the outside of the enclosing tube and shields β rays in the eighth aspect.

A Geiger-Muller counter tube according to a tenth aspect is the first to seventh aspects, wherein the space includes a first electrode pair formed by an anode electrode and a cathode electrode and fixed to one end of the enclosing tube, and a first electrode pair. And a second electrode pair fixed to the other end of the enclosing tube, and a plane including the anode electrode of the first electrode pair and a plane including the anode electrode of the second electrode pair are mutually connected Intersect at right angles.

A radiation meter according to an eleventh aspect includes a Geiger-Muller counter tube according to the first aspect to the tenth aspect, one high voltage circuit unit that applies a predetermined high voltage between the anode electrode and the cathode electrode, and a high voltage circuit And a counter that counts the pulse signal measured by the Geiger-Muller counter and a calculation unit that converts the pulse signal counted by the counter into a radiation dose.

According to the Geiger-Muller counter and the radiation meter of the present invention, stable radiation measurement can be performed and β-ray detection sensitivity can be increased.

1A is a schematic partial perspective view of a Geiger-Muller counter tube 100. FIG. FIG. 4B is a partial plan view of the cathode electrode 130. (C) is a schematic side view of the Geiger-Muller counter tube 100. FIG. 1 is a schematic configuration diagram of a radiation meter 10. (A) is a general | schematic fragmentary perspective view of the conventional Geiger-Muller counter tube 100a. (B) is a graph showing the relationship between the electric field ε (r) and the distance r. (C) is a graph showing the relationship between the electric field ε (x) and the distance x. (A) is a schematic partial perspective view of the Geiger-Muller counter tube 200. FIG. (B) is a schematic partial perspective view of the Geiger-Muller counter tube 300. FIG. 2 is a schematic partial perspective view of a Geiger-Muller counter tube 400. FIG. (A) is a schematic partial perspective view of the Geiger-Muller counter tube 500. FIG. (B) is a schematic side view of the Geiger-Muller counter tube 500. FIG. (A) is a schematic partial perspective view of the Geiger-Muller counter tube 600. FIG. (B) is a schematic side view of the Geiger-Muller counter tube 600. FIG. (A) is a schematic partial side view of the Geiger-Muller counter tube 700. FIG. FIG. 5B is a schematic side view of the Geiger-Muller counter tube 700 attached to the substrate 150. 2 is a schematic configuration diagram of a radiation meter 70. FIG. (A) is a schematic side view of the Geiger-Muller counter tube 800. FIG. (B) is a schematic block diagram of the radiation meter 80. 2 is a schematic partial perspective view of a Geiger-Muller counter tube 900. FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. It should be noted that the scope of the present invention is not limited to these forms unless otherwise specified in the following description.

(First embodiment)
<Configuration of Geiger-Muller counter 100>
FIG. 1A is a schematic partial perspective view of the Geiger-Muller counter tube 100. The Geiger-Muller counter tube 100 is mainly formed by an enclosure tube 110, an anode electrode 120 enclosed in the enclosure tube 110, and a cathode electrode 130 enclosed in the enclosure tube 110. The enclosure tube 110 is a glass tube having a cylindrical outer shape, for example. In the following description, the direction in which the sealed tube 110 extends is the Z-axis direction, the diameter direction of the sealed tube 110 and the direction perpendicular to the Z-axis direction is the X-axis direction, and the diameter direction of the sealed tube 110 is also the X-axis direction and Z A direction perpendicular to the axial direction is taken as a Y-axis direction.

The anode electrode 120 and the cathode electrode 130 are formed in a rectangular flat plate shape, and are configured as a wire mesh in which a plurality of metal wires are knitted in a mesh shape. The anode electrode 120 and the cathode electrode 130 are both formed on the XZ plane, and are arranged so that their main surfaces face each other and overlap in the Y-axis direction. A linear anode conductor 121 is joined to the anode electrode 120, and a linear cathode conductor 131 is joined to the cathode electrode 130.

An inert gas and a quench gas are sealed in the internal space 111 of the sealed tube 110 together with the anode electrode 120 and the cathode electrode 130. As the inert gas, for example, a rare gas such as helium (He), neon (Ne), or argon (Ar) is used. As the quench gas, for example, a halogen-based gas such as fluorine (F), bromine (Br), or chlorine (Cl) is used.

FIG. 1B is a partial plan view of the cathode electrode 130. For example, as shown in FIG. 1B, the cathode electrode 130 is formed as a wire mesh by knitting a plurality of metal wires 151 arranged in parallel with the X axis and the Z axis into a net shape. A plurality of meshes 152 are formed in the metal mesh, and the meshes 152 are through holes that penetrate the cathode electrode 130 in the Y-axis direction. The anode conductor 120 is also formed in the same manner as the cathode conductor 130. The metal wire 151 is made of, for example, metal Kovar or stainless steel, which is an alloy of iron, nickel, and cobalt.

FIG. 1 (c) is a schematic side view of the Geiger-Muller counter tube 100. Both ends of the enclosing tube 110 in the Z-axis direction are closed, and the cathode conductor 131 and the anode conductor 121 pass through the −Z-axis end of the enclosing tube 110 and are drawn to the outside of the enclosing tube 110. The anode electrode 120 and the cathode electrode 130 are arranged in parallel with a distance d therebetween. Further, a region sandwiched between the anode electrode 120 and the cathode electrode 130 is a radiation detection space 112 for detecting radiation. Since β-ray, which is one of the radiations, has a low transmission power, it is easily blocked by a shield. However, in the Geiger-Muller counter tube 100, a mesh 152 serving as a through hole is formed in the anode electrode 120 and the cathode electrode 130. Β rays incident on the Geiger-Muller counter 100 from the axis side and the −Y axis side can be guided to the radiation detection space 112 via the mesh 152.

In the Geiger-Muller counter tube 100, an electric field is formed in the radiation detection space 112 by applying a voltage of, for example, several hundred volts between the anode electrode 120 and the cathode electrode. When radiation enters the radiation detection space 112, the radiation ionizes the inert gas into positively charged ions and negatively charged electrons, and the ionized ions and electrons are the cathode electrode 130 and the anode electrode 120, respectively. Accelerate towards The accelerated ions collide with other inert gases and ionize the other inert gases. By repeating such ionization, ionized ions and electrons increase in an avalanche state in the radiation detection space 112 and a pulse current flows. Such avalanche-like electrons are called electronic avalanches. The radiation measuring instrument 10 (see FIG. 2) having the Geiger-Muller counter 100 can measure the radiation dose by measuring the number of pulses of the pulse signal by such a pulse current. Further, when such a current flows continuously, the number of pulses cannot be measured. To prevent this, a quench gas is enclosed in the internal space 111 together with an inert gas. The quench gas serves to lose the energy of ions.

<Configuration of radiation meter 10>
FIG. 2 is a schematic configuration diagram of the radiation meter 10. The radiation measuring instrument 10 includes a Geiger-Muller counter tube 100. The anode conductor 121 and the cathode conductor 131 are connected to the high voltage circuit unit 21, and a high voltage is applied between the two conductors. The high voltage circuit unit 21 is connected to the counter 22, and the pulse signal detected in the radiation detection space 112 of the Geiger-Muller counter tube 100 is counted by the counter 22. The count at the counter 22 is converted into a radiation dose by the calculation unit 23, and the converted radiation dose is displayed on the display unit 24. The calculator 23 is supplied with electric power when the power source 25 is connected thereto.

<Comparison between Geiger-Muller counter tube 100 and conventional Geiger-Muller counter tube 100a>
FIG. 3A is a schematic partial perspective view of a conventional Geiger-Muller counter tube 100a. The Geiger-Muller counter tube 100a includes a rod-shaped anode electrode 120a extending in the Z-axis direction and a cylindrical cathode electrode 130a surrounding the anode electrode 120a. An anode conductor 121 is joined to the anode electrode 120a, and a cathode conductor 131 is joined to the cathode electrode 130a. In the Geiger-Muller counter tube 100a, a region surrounded by the cathode electrode 130a is a radiation detection space 112a.

The anode electrode 120a is disposed on the central axis of the cathode electrode 130a. The radius of the anode electrode 120a is a, half the inner diameter of the cathode electrode 130a is b, the distance from the central axis of the cathode electrode 130a at an arbitrary position in the radiation detection space 112a is r, and the anode electrode 120a and the cathode electrode 130a Assuming that the voltage between and is V ₀ , the electric field ε (r) at an arbitrary position in the radiation detection space 112a is expressed by the following equation (1). ε (r) = V ₀ / (r × ln (b / a)) (1)

FIG. 3B is a graph showing the relationship between the electric field ε (r) and the distance r. In FIG. 3B, the horizontal axis indicates the distance r, and the vertical axis indicates the electric field ε (r). FIG. 3B shows a solid line 160 represented by the expression (1). As indicated by the solid line 160, the magnitude of the electric field ε (r) decreases with increasing distance r from the position r = a, which is the surface of the anode electrode 120a. In addition, when the minimum electric field size necessary for causing an avalanche is ε ₁ and the distance r in Equation (1) at this time is c, the electron avalanche occurs in the range of a <r ≦ c. Become. That is, when c <b, radiation is not detected in the entire region surrounded by the cathode electrode 130a, but an electron avalanche occurs only around the anode electrode 120a. Thus, in the Geiger-Muller counter tube 100a, since there is an electric field intensity attenuation around the anode electrode 120a depending on the distance from the anode electrode 120a, the relative position shift or voltage V ₀ between the anode electrode 120a and the cathode electrode 130a. A region where an electronic avalanche occurs due to a slight change in the amount of change may cause measurement sensitivity to fluctuate, resulting in unstable measurement results.

FIG. 3C is a graph showing the relationship between the electric field ε (x) and the distance x. In FIG. 3C, the horizontal axis indicates the distance x, and the vertical axis indicates the electric field ε (x). The electric field ε (x) indicates the magnitude of the electric field at an arbitrary position when the distance from the anode electrode 120 is x in the radiation detection space 112 of the Geiger-Muller counter tube 100 (see FIG. 1C). ing. The distance x is 0 ≦ x ≦ d. The electric field ε (x) is expressed by the following formula (2), where V ₀ is the voltage between the anode electrode 120 and the cathode electrode 130, and d is the distance between the anode electrode 120 and the cathode electrode 130. ε (x) = V ₀ / d (2)

FIG. 3C shows a solid line 161 expressed by the equation (2). As indicated by the equation (2) and the solid line 161, the magnitude of the electric field ε (x) does not depend on the distance x and takes a constant value. Therefore, when the electric field epsilon (x) is greater than epsilon _1, the radiation can be detected in the entire region of the radiation detection space 112 (see FIG. 1 (c)).

Measured radiation mainly includes β-rays and γ-rays, but β-rays are not as strong as γ-rays, so they are not as problematic as γ-rays as external exposure factors. However, when a radioactive substance that emits β-rays is taken into the body, all of the radiant energy is absorbed, so that the human body is more damaged than when γ-ray nuclides are taken into the body. For example, radioactive strontium is a radioactive substance that emits β-rays, but if radioactive strontium is taken into the body, it accumulates in the bone and continues to emit radiation, which is dangerous.

Since radioactive strontium poses a danger to the human body, it is necessary to know the presence or absence of radioactive strontium. However, since radioactive strontium only emits β-rays, it could not be detected by a Geiger-Muller counter specialized for measuring γ-rays. Further, the conventional Geiger-Muller counter tube 100a as shown in FIG. 3A uses a thin metal sheet for the cathode electrode 130a, so that some β-rays pass, but the β-rays are greatly attenuated when passing through the metal sheet. The β-ray detection sensitivity was low.

In the Geiger-Muller counter 100 (see FIG. 1A), a mesh 152 serving as a through-hole is formed in each of the anode electrode 120 and the cathode electrode 130, so that β-rays are incident into the radiation detection space 112 through the mesh 152. be able to. As a result, it is possible to measure β rays without greatly reducing the detection sensitivity of β rays.

Further, in the conventional Geiger-Muller counter tube 100a (see FIG. 3A), between the radiation detection space 112a and the internal space 111 other than the radiation detection space 112a due to ionization of an inert gas due to radiation in the sealed tube 110. In some cases, a difference in concentration of inert gas or the like is likely to occur, and the detection sensitivity of radiation may be lowered. In the Geiger-Muller counter tube 100, the mesh 152 is formed in each of the anode electrode 120 and the cathode electrode 130, whereby the gas flow between the radiation detection space 112 and the internal space 111 other than the radiation detection space 112 is improved. The flow of gas in the tube 110 is easily promoted. As a result, in the Geiger-Muller counter tube 100, the concentration difference of inert gas or the like between the radiation detection space 112 and the internal space 111 other than the radiation detection space 112 is alleviated, and a decrease in radiation detection sensitivity is prevented. Yes.

Also, in the Geiger-Muller counter tube 100, when the areas of the anode electrode 120 and the cathode electrode 130 are large, the amount of β-rays detected is highest when measuring β-rays flying from the Y-axis direction. Therefore, the direction in which the radiation comes can be identified by directing the Geiger-Muller counter tube 100 in various directions and examining the direction in which the detected amount of radiation increases.

Further, in the conventional Geiger-Muller counter tube 100a, the measurement sensitivity may fluctuate due to the electric field intensity attenuation depending on the distance from the anode electrode 120a, and the measurement results may vary. On the other hand, in the Geiger-Muller counter tube 100, the radiation detection space 112 is constant without attenuation of the electric field strength, and the size of the region where the electron avalanche occurs is also constant. Therefore, the Geiger-Muller counter tube 100 can perform stable measurement of radiation including β rays.

(Second Embodiment)
At least one of the anode electrode and the cathode electrode may be composed of other than a metal net. Hereinafter, a modified example of the Geiger-Muller counter tube in which at least one of the anode electrode and the cathode electrode is formed of a material other than the metal net is shown. In the following description, the same parts as those in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and the description thereof is omitted.

<Configuration of Geiger-Muller counter 200>
FIG. 4A is a schematic partial perspective view of the Geiger-Muller counter tube 200. The Geiger-Muller counter tube 200 mainly includes an enclosure tube 110, an anode electrode 220 disposed in the enclosure tube 110, and an inside of the enclosure tube 110 so as to overlap with the anode electrode 220 by a predetermined distance in the + Y-axis direction. And a cathode electrode 230 disposed on the substrate. An anode conductor 121 is joined to the anode electrode 220, and a cathode conductor 131 is joined to the cathode electrode 230. That is, the Geiger-Muller counter tube 200 has a configuration in which the anode electrode 120 is replaced with the anode electrode 220 and the cathode electrode 130 is replaced with the cathode electrode 230 in the Geiger-Muller counter tube 100.

In the Geiger-Muller counter tube 100 shown in FIG. 1A, a metal plate may be used for the anode electrode 120 and the cathode electrode 130 instead of the wire mesh. The metal plate can be formed of, for example, a metal Kovar that is an alloy of iron, nickel, or cobalt, or a stainless steel rectangular metal plate. In the Geiger-Muller counter tube 200 shown in FIG. 4A, metal plates are used for the anode electrode 220 and the cathode electrode 230, and a plurality of through holes 221 are formed in the anode electrode 220. Through-holes 231 are formed.

In the Geiger-Muller counter tube 200, by using flat metal plates for the anode electrode 220 and the cathode electrode 230, it is possible to perform stable measurement of radiation including β-rays, and by forming through holes in each electrode. Improvement of β-ray measurement sensitivity is achieved.

<Configuration of Geiger-Muller counter 300>
FIG. 4B is a schematic partial perspective view of the Geiger-Muller counter tube 300. The Geiger-Muller counter tube 300 mainly includes an enclosing tube 110, an anode electrode 320 disposed in the enclosing tube 110, and an inside of the enclosing tube 110 so as to overlap the anode electrode 320 by a predetermined distance in the + Y axis direction. And a cathode electrode 330 disposed on the substrate. The anode electrode 320 is formed in a planar shape, and the anode electrode 320 and the anode conductor 321 connected to the anode electrode 320 are integrally formed by bending one bar. The cathode electrode 330 and the cathode conductor 331 connected to the cathode electrode 330 are also formed in the same shape as the anode electrode 320 and the anode conductor 321.

In the Geiger-Muller counter tube 300, the anode electrode 320 and the cathode electrode 330 are formed in a flat plate shape, but each electrode is formed by bending one rod so that the density is sparse. Many gaps are formed as shown in b). This gap serves as a through hole for each electrode, thereby improving the β-ray measurement sensitivity.

<Configuration of Geiger-Muller Counter 400>
FIG. 5 is a schematic partial perspective view of the Geiger-Muller counter tube 400. The Geiger-Muller counter tube 400 is configured by replacing the anode electrode 120 with an anode electrode 420 formed of a rectangular metal plate in the Geiger-Muller counter tube 100 shown in FIG. That is, the Geiger-Muller counter tube 100 and the Geiger-Muller counter tube 400 differ only in the configuration of the anode electrode.

In the Geiger-Muller counter tube 100, when detecting β-rays flying from the ± Y-axis direction, the amount of β-rays detected is the highest. However, in the Geiger-Muller counter tube 400, β-rays flying from the −Y-axis side are anode electrodes 420. Therefore, when detecting β rays flying from the + Y axis side, the detection amount of β rays is the highest. Therefore, in the Geiger-Muller counter tube 400, the direction in which β rays come in can be specified by examining the direction in which the detection amount of β rays becomes the highest.

(Third embodiment)
A plurality of anode electrodes and / or cathode electrodes may be arranged. The Geiger-Muller counter tube in which a plurality of at least one of the anode electrode and the cathode electrode are arranged is shown below. In the following description, the same parts as those in the first embodiment or the second embodiment are denoted by the same reference numerals as those in the first embodiment or the second embodiment, and the description thereof is omitted.

<Configuration of Geiger-Muller counter 500>
FIG. 6A is a schematic partial perspective view of the Geiger-Muller counter tube 500. The Geiger-Muller counter tube 500 mainly includes an enclosed tube 510 having an internal space 511, an anode electrode 120 disposed in the internal space 511, and a cathode electrode 530a disposed on the + Y axis side of the anode electrode 120 in the internal space 511. The cathode electrode 530b disposed on the −Y-axis side of the anode electrode 120 in the internal space 511. The anode conductor 121 is joined to the anode electrode 120, the cathode conductor 531a is joined to the cathode electrode 530a, and the cathode conductor 531b is joined to the cathode electrode 530b. The cathode electrode 530a and the cathode electrode 530b are formed with the same configuration as the cathode electrode 130 (see FIG. 1A), and the cathode conductor 531a and the cathode conductor 531b have the same configuration as the cathode conductor 131 (see FIG. 1A). It is formed by.

FIG. 6B is a schematic side view of the Geiger-Muller counter tube 500. The anode electrode 120, the cathode electrode 530a, and the cathode electrode 530b are arranged so as to overlap in the Y-axis direction. Further, the distance between the cathode electrode 530a and the anode electrode 120 and the distance between the cathode electrode 530b and the anode electrode 120 are arranged to be the distance d2. In the Geiger-Muller counter tube 500, for example, the cathode conductor 531a and the cathode conductor 531b are electrically connected to each other, whereby a constant voltage is applied between the anode electrode 120 and the

cathode electrodes

530a and 530b.

In the equation (2), when the voltage V ₀ is not changed, the electric field ε (x) increases as the distance d between the electrodes is shortened. Therefore, in the Geiger-Muller counter tube 100 (see FIG. 1C), the electric field ε (x) can be adjusted to be larger than ε ₁ by adjusting the distance d between the electrodes. However, when the distance d is too short, the radiation passes through the radiation detection space 112 without causing an electron avalanche, and the radiation detection sensitivity is lowered. In addition, if the distance d between the electrodes is too wide, the electric force lines between the electrodes protrude outside the electrodes and the size of the region for detecting β-rays becomes unstable, and the measurement accuracy may be lowered.

In the Geiger-Muller counter tube 500, the distance between the electrodes is adjusted to a distance at which the electric lines of force between the electrodes are kept uniform, and the electrodes are arranged so as to overlap each other in the Y-axis direction of the radiation detection space. The length is increased, so that β-rays can be captured more reliably in the radiation detection space.

<Configuration of Geiger-Muller counter 600>
FIG. 7A is a schematic partial perspective view of the Geiger-Muller counter tube 600. The Geiger-Muller counter 600 mainly includes a sealed tube 610 having an internal space 611, a plurality of anode electrodes 620a to 620d disposed in the internal space 611, and a plurality of cathode electrodes 630a to 630d disposed in the internal space 611. , Is configured. The anode electrodes 620a to 620d and the cathode electrodes 630a to 630d are alternately arranged such that the main surfaces of the electrodes are directed in the Z-axis direction, and the anode electrode and the cathode electrode are spaced apart and overlap in the Z-axis direction. . The anode electrodes 620a to 620d are joined to the anode conductor 621, and the cathode electrodes 630a to 630d are joined to the cathode conductor 631.

The sealed tube 610 is formed of, for example, a cylindrical glass tube extending in the Z-axis direction. The plurality of anode electrodes 620a to 620d and the plurality of cathode electrodes 630a to 630d are each formed in a flat plate shape by bending a single metal wire into a spiral shape. Each electrode has a substantially disk shape, and the main surface of each electrode is arranged in the Z-axis direction, so that the size of the outer shape of the sealed tube 610 does not increase. Can be placed well. Moreover, since each electrode is wound loosely, a gap is formed between the metal wires. By this gap, β rays flying from the Z-axis direction can be captured, and the gas flow in the sealed tube 610 can be improved.

FIG. 7B is a schematic side view of the Geiger-Muller counter 600. The anode electrode and the cathode electrode are arranged in the order of the cathode electrode 630a, the anode electrode 620a, the cathode electrode 630b, the anode electrode 620b, the cathode electrode 630c, the anode electrode 620c, the cathode electrode 630d, and the anode electrode 620d from the + Z-axis side. ing. Thus, since the disk-shaped electrodes are arranged side by side in the Z-axis direction, the outer shape of the radiation detection space 612 formed between the electrodes is formed in a cylindrical shape extending in the Z-axis direction.

In the Geiger-Muller counter 600, the radiation detection space 612 for detecting β rays is formed long in the Z-axis direction, so that radiation flying from the Z-axis direction can be captured and observed more reliably. Further, as shown in FIG. 7B, when the radiation detection space 612 is viewed from the diameter direction of the sealed tube 610, the density of the electrodes is low, and therefore β rays flying from the diameter direction of the sealed tube 610 are measured. In this case, β-rays are hardly blocked by each electrode, so that the detection sensitivity of β-rays can be increased.

(Fourth embodiment)
A plurality of electrode pairs formed by a combination of the anode electrode and the cathode electrode may be arranged in the sealed tube. Hereinafter, a Geiger-Muller counter tube in which a plurality of electrode pairs are arranged in an enclosed tube will be described. In the following description, the same parts as those in the first to third embodiments are denoted by the same reference numerals as those in the first to third embodiments, and the description thereof is omitted.

<Configuration of Geiger-Muller counter 700>
FIG. 8A is a schematic partial side view of the Geiger-Muller counter 700. FIG. The Geiger-Muller counter tube 700 mainly includes a sealed tube 710 formed of a cylindrical glass tube extending in the Z-axis direction and having an internal space 711, a first electrode pair 760a disposed in the internal space 711, and an internal space 711. The second electrode pair 760b is arranged.

The first electrode pair 760 a is formed by a combination of the anode electrode 120 and the cathode electrode 130, the anode conductor 121 is joined to the anode electrode 120, and the cathode conductor 131 is joined to the cathode electrode 130. The configuration of the first electrode pair 760a is the same as the combination of the anode electrode 120 and the cathode electrode 130 of the Geiger-Muller counter tube 100 (see FIG. 1C). The first electrode pair 760a is disposed on the −Z-axis side of the internal space 711 of the enclosed tube 710, and the anode conductor 121 and the cathode conductor 131 are drawn out of the enclosed tube 710 from the −Z-axis side end of the enclosed tube 710. Yes.

The second electrode pair 760b is formed by a combination of an anode electrode 720 and a cathode electrode 730. An anode conductor 721 is joined to the anode electrode 720, and a cathode conductor 731 is joined to the cathode electrode 730. The anode electrode 720, cathode electrode 730, anode conductor 721, and cathode conductor 731 are formed in the same shape as the anode electrode 120, cathode electrode 130, anode conductor 121, and cathode conductor 131, respectively, and the second electrode pair 760b is the first electrode. It is formed in the same shape as the pair 760a. The second electrode pair 760 b is disposed on the + Z axis side of the internal space 711, and the anode conductor 721 and the cathode conductor 731 are drawn to the outside of the enclosure tube 710 from the + Z axis side end of the enclosure tube 710.

In the first electrode pair 760a and the second electrode pair 760b, the anode electrode 120 and the anode electrode 720 are disposed on the −Y axis side of the cathode electrode 130 and the cathode electrode 730, and the anode electrode 120 and the anode electrode 720 are disposed on the same plane. The cathode electrode 130 and the cathode electrode 730 are disposed on the same plane. Since the anode electrodes and the cathode electrodes are arranged on the same plane, even if the distance between the first electrode pair 760a and the second electrode pair 760b is narrowed, the anode electrode and the cathode electrode are short-circuited, or The electric field of the first electrode pair 760a and the second electrode pair 760b is prevented from being disturbed.

When using multiple Geiger-Muller counters for reasons such as increasing the radiation detection sensitivity, the accuracy of radiation detection may be reduced due to individual differences in the sensitivity of individual Geiger-Muller counters. In the Geiger-Muller counter 700, the radiation detection sensitivity is increased by arranging two pairs of electrodes in one Geiger-Muller counter. Moreover, in the Geiger-Muller counter 700, since the inert gas and quench gas of each electrode pair are used in common, the ratio of the inert gas and quench gas in each electrode pair is the same. Therefore, the Geiger-Muller counter tube 700 can improve the accuracy of radiation detection compared to the case where two sets of Geiger-Muller counter tubes are used.

FIG. 8B is a schematic side view of the Geiger-Muller counter tube 700 attached to the substrate 150. The Geiger-Muller counter tube 700 is used by being fixed to the substrate 150, for example. In the conventional Geiger-Muller counter tube 100a (see FIG. 3A), the electrode is drawn out only from one end of the enclosed tube, and is fixed to the substrate or the like only by one end of the Geiger-Muller counter tube. In contrast, in the Geiger-Muller counter tube 700, electrodes are drawn from both ends of the enclosed tube 710, and as shown in FIG. 8B, both ends on the + Z-axis side and the −Z-axis side of the Geiger-Muller counter tube 700 are shown. To be fixed to the substrate 150. Therefore, the Geiger-Muller counter tube 700 can be firmly and stably fixed to the substrate 150 or the like as compared with the conventional Geiger-Muller counter tube.

<Configuration of radiation meter 70>
FIG. 9 is a schematic configuration diagram of the radiation meter 70. The radiation measuring instrument 70 includes a Geiger-Muller counter tube 700. The anode conductor 121 and the cathode conductor 131 are connected to the first high voltage circuit portion 21a, and a high voltage is applied between the two conductors. The anode conductor 721 and the cathode conductor 731 are connected to the second high voltage circuit unit 21b, and a high voltage is applied between the two conductors. The first high voltage circuit unit 21a is connected to the first counter 22a, and the second high voltage circuit unit 21b is connected to the second counter 22b. The pulse signals detected by the first electrode pair 760a and the second electrode pair 760b of the Geiger-Muller counter 700 are respectively counted by the first counter 22a and the second counter 22b, converted into a radiation dose by the calculation unit 23, and converted. The radiation dose is displayed on the display unit 24. The calculator 23 is supplied with electric power when the power source 25 is connected thereto.

In the radiation measuring instrument 70, the first electrode pair 760a and the second electrode pair 760b are individually connected to different high voltage circuit units and counters to individually detect the radiation dose. However, even if the first electrode pair 760a and the second electrode pair 760b are connected in parallel to one high voltage circuit unit and a counter and the radiation dose as a whole of the first electrode pair 760a and the second electrode pair 760b is detected. Good.

(Fifth embodiment)
The radiation dose detected by the Geiger-Muller counter 700 is measured as the total value of the radiation doses of both β rays and γ rays. On the other hand, there is a case where it is desired to measure each radiation dose of β rays and γ rays. Below, the Geiger-Muller counter 800 and the radiation meter 80 for measuring each radiation dose of β rays and γ rays will be described. In the following description, the same parts as those in the first to fourth embodiments are denoted by the same reference numerals as those in the first to fourth embodiments, and the description thereof is omitted.

<Configuration of Geiger-Muller counter 800>
FIG. 10A is a schematic side view of the Geiger-Muller counter tube 800. The Geiger-Muller counter tube 800 is formed by attaching a shielding portion 153 that shields β rays so as to surround the first electrode pair 760 a of the Geiger-Muller counter tube 700 from the outside of the enclosing tube 710. The shield 153 can be formed as an aluminum cylindrical tube, for example.

In the Geiger-Muller counter 800, β rays and γ rays can be detected in the second electrode pair 760b that is not covered with the shielding portion 153. In the first electrode pair 760a covered with the shielding part 153, β rays are shielded by the shielding part 153, so that only γ rays can be detected. The radiation dose of β rays can be obtained by subtracting the radiation dose of the first electrode pair 760a from the radiation dose of the second electrode pair 760b.

Conventionally, two Geiger-Muller counters have been prepared for simultaneous measurement of γ rays and β rays. One Geiger-Muller counter tube is placed in an aluminum tube or the like to block β rays and measure only γ rays. Further, β rays and γ rays are measured with the other Geiger-Muller counter tube. The β ray is obtained by subtracting the radiation dose of one Geiger-Muller counter tube from the radiation dose of the other Geiger-Muller counter tube.

On the other hand, the Geiger-Muller counter 800 can simultaneously measure both β-ray and γ-ray radiation with a single Geiger-Muller counter. Therefore, it is possible to save the trouble of preparing a plurality of Geiger-Muller counter tubes, so that the measurement becomes easy. Further, similarly to the Geiger-Muller counter tube 700, since the inert gas and the quench gas are commonly used in the first electrode pair 760a and the second electrode pair 760b, compared to the case where two sets of Geiger-Muller counter tubes are used. Can also increase the accuracy of radiation detection.

<Configuration of radiation meter 80>
FIG. 10B is a schematic configuration diagram of the radiation meter 80. In the radiation measuring instrument 80, the Geiger-Muller counter tube 800 is used instead of the Geiger-Muller counter tube 700 in the radiation measuring instrument 70 shown in FIG. 9, and a position determination unit 26 for determining the position of the shielding unit 153 is provided. It has been. In the state shown in FIG. 10B, the first counter 22a connected to the first electrode pair 760a shielded by the shield 153 detects the radiation dose of only γ rays. The second counter 22b connected to the second electrode pair 760b detects the total radiation dose of γ rays and β rays. Therefore, the radiation meter 80 detects the radiation dose of γ rays based on the radiation dose of the first electrode pair 760a, and subtracts the radiation dose of the first electrode pair 760a from the radiation dose of the second electrode pair 760b. The radiation dose can be detected. These calculations are performed by the calculation unit 23, and the results can be further displayed on the display unit 24.

Further, the radiation measuring instrument 80 is formed so that the shielding portion 153 can be freely detached from and attached to the first electrode pair 760a. For example, the first electrode pair 760a and the second electrode pair 760b are measured under the same conditions by moving the shield 153 from the state of FIG. 10B in the −Z-axis direction to expose the first electrode pair 760a. It can be carried out. By performing measurement in this state, it is possible to calibrate the radiation dose detection value between the first electrode pair 760a and the second electrode pair 760b.

Further, for example, a sensor (not shown) for detecting whether the Geiger-Muller counter tube 800 is attached or detached is attached to the shielding part 153, so that the attachment / detachment of the shielding part 153 is automatically determined. You may let them. The sensor is connected to a position determination unit 26 that determines the position of the shielding unit 153, and the position determination unit 26 is connected to the calculation unit 23. When the position determination unit 26 determines that the shielding unit 153 is attached to the Geiger-Muller counter tube 800, the calculation unit 23 detects γ-rays from the first electrode pair 760a, and detects from the second electrode pair 760b Β rays are automatically detected by subtracting the radiation dose of one electrode pair 760a. When the position determination unit 26 determines that the Geiger-Muller counter tube 800 is not equipped with the shielding unit 153, the radiation amount of the first electrode pair 760a and the second electrode pair 760b is displayed on the display unit 24. The display on the display unit 24 may display an average of the radiation doses of the first electrode pair 760a and the second electrode pair 760b.

(Sixth embodiment)
Geiger-Muller counters, in which the anode and cathode electrodes are formed in a flat plate shape, vary greatly in the amount of radiation detected depending on the angle in which the radiation comes in. You may want to relax. The Geiger-Muller counter 900 in which the angle dependency of the radiation detection amount is relaxed will be described below. In the following description, the same parts as those in the first to fifth embodiments are denoted by the same reference numerals as those in the first to fifth embodiments, and the description thereof is omitted.

<Configuration of Geiger-Muller counter 900>
FIG. 11 is a schematic partial perspective view of the Geiger-Muller counter tube 900. The Geiger-Muller counter tube 900 mainly includes an enclosing tube 710, a first electrode pair 960a disposed in the enclosing tube 710, and a second electrode pair 960b disposed in the enclosing tube 710.

The first electrode pair 960a is formed so that the anode electrode 920a and the cathode electrode 930a overlap each other with a distance in the Y-axis direction, the anode conductor 920a is joined to the anode electrode 920a, and the cathode electrode 930a is joined to the cathode electrode 930a. The conductor 931a is joined. The second electrode pair 960b is formed such that an anode electrode 920b (not shown) and a cathode electrode 930b overlap each other with a distance in the Y-axis direction, and an anode conductor 921b (not shown) is joined to the anode electrode 920b. The cathode conductor 931b is joined to the cathode electrode 930b.

The anode electrode 920a of the first electrode pair 960a and the anode electrode of the second electrode pair 960b are formed in the same shape as the anode electrode 120 (see FIG. 1A), and the cathode electrode 930a and the cathode electrode 930b are formed of the cathode electrode 130 (FIG. 1 (a)). The first electrode pair 960a and the second electrode pair 960b are formed in the same shape, but the anode electrode 920a and the cathode electrode 930a constituting the first electrode pair 960a are arranged in parallel to the XZ plane, and the second electrode pair The anode electrode 920b and the cathode electrode 930b constituting the 960b are arranged in parallel to the YZ plane. That is, the second electrode pair 960b is arranged in a state in which the first electrode pair 960a is rotated 90 degrees about the Z axis as a rotation axis.

The Geiger-Muller counter formed by the flat anode and cathode electrodes has a radiation detection space formed in a rectangular parallelepiped, so the radiation detection sensitivity varies greatly depending on which direction the Geiger-Muller counter is facing, In some cases, almost no radiation is detected. In the Geiger-Muller counter tube 900, the second electrode pair 960b is rotated by 90 degrees with respect to the first electrode pair 960a, so that radiation can be detected from any direction in the diameter direction of the enclosed tube. can do.

As described above, the optimal embodiment of the present invention has been described in detail. However, as will be apparent to those skilled in the art, the present invention can be implemented with various modifications and variations within the technical scope thereof. Moreover, the features of each embodiment can be implemented in various combinations.

For example, the sealed tube shown in the above embodiment is cylindrical, but can be formed in various shapes other than cylindrical. For example, the enclosed tube of the Geiger-Muller counter tube 100 shown in FIG. 1A may be shaped like a rectangular parallelepiped in accordance with the shapes of the anode electrode and the cathode electrode.

DESCRIPTION OF

SYMBOLS

10, 70, 80 ... Radiation meter 21 ... High voltage circuit part 21a ... 1st high voltage circuit part 21b ... 2nd high voltage circuit part 22 ... Counter 22a ... 1st counter 22b ... 2nd counter 23 ... Calculation part 24 ... Display unit 25 ... Power supply 26 ...

Position determination unit

100, 200, 300, 400, 500, 600, 700, 800, 900 ... Geiger-Muller counter tube 100a ... Conventional Geiger-

Muller counter tube

110, 510, 610, 710 ... Encapsulated

tube

111, 511, 611, 711 ...

Internal space

112, 112a, 612 ...

Radiation detection space

120, 120a, 220, 320, 420, 620a to 620d, 720, 920a ...

Anode electrode

121, 321, 621, 721, 921a ...

Anode Conductor

130, 130a, 230, 330, 5 0a, 530b, 630a to 630d, 730, 930a, 930b ...

Cathode electrode

131, 331, 531a, 531b, 631, 731, 931a, 931b ... Cathode conductor 150 ... Substrate 151 ... Metal wire 152 ... Mesh 153 ... Shielding part 160 ... Solid line 161 representing the equation (1) ... Solid line representing the equation (2) 760a, 960a ...

First electrode pair

760b, 960b ... Second electrode pair a ... Radius of the anode electrode 120a b ... Half of the inner diameter of the cathode electrode 130a c ... The value of the distance r when ε (r) = ε ₁ d... Distance between the anode electrode 120 and the cathode electrode 130

Claims

An enclosed tube having a sealed space;
An anode electrode disposed in the space and formed in a flat plate shape;
A cathode electrode formed in a flat plate shape and disposed in parallel with the anode electrode in the space at a predetermined interval from the anode electrode;
A Geiger-Muller counter provided with an inert gas and a quench gas sealed in the space.
2. The Geiger-Muller counter tube according to claim 1, wherein at least one of the anode electrode and the cathode electrode is formed of a wire mesh in which a plurality of metal wires are knitted in a mesh shape.
The Geiger-Muller counter tube according to claim 1, wherein at least one of the anode electrode and the cathode electrode is formed of a metal plate.
The Geiger-Muller counter tube according to claim 3, wherein the metal plate is formed with a plurality of through holes penetrating the metal plate.
The Geiger-Muller counter tube according to claim 1, wherein at least one of the anode electrode and the cathode electrode is formed in a flat plate shape by bending one metal wire.
6. The cathode electrode according to claim 1, wherein the cathode electrode is constituted by two plate-like electrodes parallel to each other, and the anode electrode is sandwiched between the two plate-like electrodes. The Geiger-Muller counter as described.
The anode electrode is composed of a plurality of flat electrodes,
The cathode electrode is composed of a plurality of flat electrodes,
The Geiger-Muller counter tube according to any one of claims 1 to 5, wherein each plate-like electrode of the anode electrode and each plate-like electrode of the cathode electrode are arranged so as to alternately overlap each other. .
In the space, a first electrode pair formed by the anode electrode and the cathode electrode and fixed to one end of the enclosure tube, and having the same configuration as the first electrode pair, the other end of the enclosure tube A second electrode pair to be fixed, and
The Geiger-Muller counter tube according to any one of claims 1 to 7, wherein the first electrode pair and the second electrode pair are arranged on the same plane.
The Geiger-Muller counter tube according to claim 8, further comprising a shielding portion that surrounds the first electrode pair from the outside of the enclosure tube and shields β rays.
In the space, a first electrode pair formed by the anode electrode and the cathode electrode and fixed to one end of the enclosure tube, and having the same configuration as the first electrode pair, the other end of the enclosure tube A second electrode pair to be fixed, and
The Geiger-Muller counter tube according to any one of claims 1 to 7, wherein a plane including the anode electrode of the first electrode pair and a plane including the anode electrode of the second electrode pair intersect at a right angle.
Geiger-Muller counter tube according to any one of claims 1 to 10,
One high voltage circuit section for applying a predetermined high voltage between the anode electrode and the cathode electrode;
A counter connected to the high-voltage circuit unit and counting a pulse signal measured by the Geiger-Muller counter;
A radiation meter comprising: a calculation unit that converts the pulse signal counted by the counter into a radiation dose.