JP6504982B2 - Ion filter and method of manufacturing the same - Google Patents

Description

  The present invention relates to an ion filter used in a gas detector provided with a gas electronic amplifier and a method of manufacturing the same.

  A gas detector is known as one of the radiation detectors. In this gas detector, a gas detector using a gas electronic amplifier in its gas electronic amplification unit is known (Patent Document 1).

Japanese Patent Application Publication No. 2007-234485

In this type of gas detector, radiation to be detected is incident, and electrons emitted from gas atoms by the photoelectric effect of radiation and gas are amplified by the electron avalanche effect using a gas electron amplifier provided with a large number of through holes. And detect the electrical signal.
When the electrons are amplified, the same number of cations as the amplified electrons are generated. The generated positive ions travel in the direction opposite to the moving direction of electrons by the influence of the electric field inside the through holes provided in the gas electron amplifier.
In addition, since the moving speed of positive ions with relatively large mass is slower than the moving speed of electrons, the shape dependent on the shape of the gas electron amplifier inside the gas detector (when using an electron amplification foil as a gas electron amplifier May collect and remain in a flat plate shape, which is the shape of an electronic amplification foil, to generate an electric field.
The electric field formed by the positive ions changes the direction of movement of the electrons that the gas detector measures.
Thus, the electric field created by the positive ions causes the so-called positive ion problem, which reduces the position resolution of the gas detector in which the gas electron amplifier is used.

  With respect to the cation problem, conventionally, a method is known in which a wire electrode is provided on the upstream side of the gas electron amplifier, and an electric field generated from the wire electrode prevents the progress of the cation. However, when used under a high magnetic field, an E × B effect occurs in the vicinity of the wire electrode, causing another problem that the orbit of the moving electron is distorted in the vicinity of the wire electrode. In addition, when preventing the movement of positive ions, there is a problem that the position resolution is lowered if even the movement of electrons is prevented by the E × B effect.

  In order to cope with the above problems, it has been proposed to dispose an ion filter that prevents the progress of positive ions on the upstream side of the gas electron amplifier. The ion filter has a function of preventing the progress of positive ions while suppressing the influence on the orbit of the moving electrons.

By the way, ILD (International Large Detector) is used in the International Linear Collider (ILC: International Linear Collider) experiment which measures the property of particles. An ILD is composed of a plurality of measuring devices. For this reason, in ILD, particles to be measured are affected by multiple coulomb scattering every time they pass each measuring instrument. In order to reduce the influence of such multiple coulomb scattering, it is necessary to reduce the object mass of each measuring instrument.
A gas detector may be used as one of the measuring devices which comprise ILD. A gas electron amplifier is provided in a gas electron amplification unit inside the gas detector. Along with the installation of the gas electron amplifier, an ion filter is provided in order to cope with the above-mentioned cation problem.
If an ion filter is arrange | positioned inside the gas detector which is one of the measuring devices which comprise ILD, the substance mass of a gas detector (measuring device) will increase by the part of an ion filter.
For this reason, in an ILD provided with a gas detector provided with an ion filter, the effect of multiple coulomb scattering that the particles receive when passing through each measuring instrument is the same as that in the ILD provided with a gas detector provided with no ion filter. There is a problem that it tends to be larger than the influence.

  The problem to be solved by the present invention is that in providing an ion filter disposed inside a gas detector, in an ILD comprising a gas detector provided with an ion filter, multiple particles received by particles passing each measuring device are received It is to suppress the influence of coulomb scattering.

FIG. 1 is a block diagram of a three-dimensional track detector (TPC: Time Projection Chamber) according to an embodiment of the present invention. FIG. 2A is a perspective view schematically showing an example of the ion filter according to the embodiment of the present invention. FIG. 2B is a plan view schematically showing an example of the ion filter according to the embodiment of the present invention. FIG. 2C is a cross-sectional view schematically showing a first example of a cross section along line IIC-IIC shown in FIG. 2B. FIG. 2D is an enlarged view of the IID area shown by a broken line in FIG. 2C. FIGS. 3A to 3E are views for explaining the method of manufacturing the ion filter of the present embodiment.

Hereinafter, embodiments of the present invention will be described based on the drawings. In the present embodiment, the ion filter according to the present invention will be described by way of an example in which it is applied to a central track detector which is one of measuring devices constituting an ILD (International Large Detector) measuring device. The ILD measuring device of the present embodiment comprises at least a central track detector. In the present embodiment, a gas detector can be used as the central track detector. More specifically, in the present embodiment, a TPC (Time Projection Chamber) 100 is used as a central track detector using a gas detector. The TPC of the present embodiment measures the track of radiation containing charged particles under a predetermined high magnetic field, and measures the position and momentum of the particle from the track of radiation. The ILD of this embodiment requires a central track detector, and a gas detector is applied to the central track detector. In the electronic amplification part of the gas detector, GEM (gas amplification foil) is adopted, and in addition, an ion filter is installed.
The ILD measuring device of the present embodiment includes four measuring devices of a Vertex detector, a TPC (Time Projection Chamber), a calorimeter, and a muon detector.

FIG. 1 is a block diagram of a TPC (Time Projection Chamber) 100 as an example of a central track detector using a gas detector according to this embodiment. As shown in FIG. 1, the TPC (Time Projection Chamber) 100 of the present embodiment is the ion filter 1, the gas electron amplifier 2, the detection electrode 3, the measuring instrument 4, the electrode 5, and the drift region DR. A space and a chamber CB are provided. Drift region DR is formed in chamber CB. In the TPC (Time Projection Chamber) 100 of this embodiment, when charged particles are made to enter the chamber filled with the detection gas, the chamber is generated by the photoelectric effect with the gas atoms that occurs when the charged particles pass through the gas. The gas molecules inside are ionized. Gas molecules ionized by the charged particles emit electrons. A TPC (Time Projection Chamber) 100 detects an electrical signal due to electrons generated when gas molecules in the chamber are ionized. Ionization of gas molecules in the chamber, that is, emission of electrons occurs along the track of radiation (including charged particles, hereinafter the same) incident on the drift region DR. The gas detector tracks the two-dimensional trajectory of charged particles by sequentially detecting the position of the electrons. In other words, the primary electrons are generated by the photoelectric effect of radiation and gas generated when charged particles enter the chamber, and these primary electrons are amplified when they reach the gas electron amplifier 2 (for example, an electron amplification foil) by an electric field. Emit secondary electrons. The gas detector tracks the radiation track by sequentially detecting the position of the secondary electrons. In addition, the TPC 100 according to the present embodiment includes a drift region that causes primary electrons ejected from gas atoms to drift due to the photoelectric effect of radiation and gas, and measures not only the two-dimensional position of the radiation track but also the three-dimensional position. Do.
Furthermore, the TPC of the present embodiment uses a particle drift time in the drift region DR to calculate a three-dimensional trajectory including the Z-axis direction. That is, TPC of this embodiment is a gas detector provided with a three-dimensional track detection function.

  The gas electron amplifier 2 of the present embodiment amplifies electrons generated when the gas molecules are ionized by the photoelectric effect of the radiation containing charged particles and the gas molecules, by the electron avalanche effect in a high electric field. By amplifying the electrons in this manner, it is possible to accurately detect an electrical signal due to the electrons generated when the gas atom is ionized. The detection electrode 3 detects an electrical signal. The detection electrode 3 outputs the detected electrical signal to the measuring instrument 4.

  The measuring instrument 4 measures the track (positional change with time) of the charged particles incident thereon using the detection signal from the detection electrode 3. That is, the passing position of charged particles passing through the inside of the TPC 100 is measured. The measuring instrument 4 outputs the measurement result of the track of the charged particles incident on the TPC 100 to the outside. The measurement data of the position of the charged particle incident on TPC 100 is used for the International Linear Collider (ILC) experiment. In the ILC experiment, measurement values obtained from a plurality of measuring devices including a gas detector such as TPC 100 are integrated to confirm the presence of particles to be observed or to measure the properties of particles to be observed.

  The TPC 100 using the gas detector of the present embodiment includes a chamber CB. The chamber CB includes a gas electron amplifier 2, an ion filter 1, a detection electrode 3, and an electrode 5. The chamber CB has a drift region DR which is a space in which charged particles move. One or more power supplies (not shown) supply power to them. The TPC 100 of the present embodiment includes the measuring instrument 4. The TPC 100 of the present embodiment includes at least a gas electron amplifier 2, an ion filter 1, and a detection electrode 3.

Each configuration will be described below.
The chamber CB forms a space filled with the detection gas. In general, a combination of a rare gas and a quencher gas is used as a detection gas to be filled in the chamber CB. The noble gas includes, for example, He, Ne, Ar, Xe and the like. The quencher gas includes, for example, CO ₂ , CH ₄ , C ₂ H ₆ , CF ₄ , C ₄ H _{10 and the} like. Although not particularly limited, the mixing ratio of the quencher gas mixed in the rare gas is preferably 5 to 30%.

  The electrode 5 forms an electric field in the chamber CB. Electrons generated when ionizing gas molecules by the photoelectric effect of radiation and gas drift to the side of the detection electrode 3 functioning as an anode in the electric field.

The gas electron amplifier 2 is a type of MPGD (Micro Pattern Gas Detector) that amplifies electrons.
In the electron amplification foil as the gas electron amplifier 2 used in the present embodiment, conductive layers such as copper are formed on both main surfaces of the sheet-like insulating base material, and have a large number of through holes. The through holes of the gas electron amplifier 2 extend in a direction substantially perpendicular to the main surface of the insulating substrate. A high electric field is formed inside the through holes by applying a potential difference of several hundred volts to the conductive layers formed on both main surfaces of the insulating substrate. When electrons enter into the through holes, they are rapidly accelerated. The accelerated electrons ionize surrounding gas molecules, and electrons are amplified in an avalanche manner (electron avalanche effect) inside the through holes. In general, the gas electron amplifier 2 is also called GEM: Gas Electron Multiplier.

  Although not particularly limited, the thickness of the gas electron amplifier 2 (electron amplification foil) is about 100 μm. As an example, it is known that the diameter of the through holes 30 is about 70 μm, and the pitch between the through holes 30 is about 140 μm. The aperture ratio of the through hole 30 of the gas electron amplifier 2 is about 23%. As a material of the insulating base material which comprises the gas electron amplifier 2, high molecular polymer materials, such as a polyimide and a liquid crystal polymer, can be used, for example. As a material of the conductive layer which comprises the gas electronic amplifier 2, copper, aluminum, gold, or boron etc. can be used, for example. The conductive layer of the gas electron amplifier 2 may be formed by sputtering deposition of a conductive material on an insulating material, may be formed by plating, or may be formed by lamination.

  The detection electrode 3 detects electrons multiplied by the avalanche effect and sends a detection signal to the measuring instrument 4. The measuring instrument 4 calculates various detection data based on the acquired signal. Although not particularly limited, the detection data is used for measurement of the trajectory of charged particles, measurement of the position and momentum of charged particles, and the like.

  In the chamber CB, electrons e generated when the gas molecules are ionized by the photoelectric effect of radiation and gas drift along the direction D indicated by the arrow. The direction D is a direction along the moving direction E of the electrons from the electrode 5 to the detection electrode 3. In the moving direction E of the electrons, one side where the electrode 5 is disposed is the upstream side, and the other side where the detection electrode 3 is disposed is the downstream side.

  Subsequently, the ion filter 1 of the present embodiment will be described.

As mentioned above, when the ionization of the gas amplifies the number of electrons, the same number of cations are generated. Among these positive ions, there are those which pass through the center of the through hole of the gas electron amplifier 2 and move (feedback) to the drift region DR.
Since the drift velocity of the positive ions is slow, for example, the positive ions stay in the drift region DR for a long time as a flat group, and locally form a high ion density location in the drift region DR. Thereby, the electric field of the drift region DR is distorted. When a magnetic field is present in the chamber, position resolution may be reduced if the drifting electrons are given an E × B effect.
In particular, the TPC 100 of the present embodiment includes a relatively long drift region along the traveling direction E of electrons in order to measure the three-dimensional position of the radiation track. For this reason, the positive ions backflowing to the drift region distort the electric field of the drift region DR, which tends to lower the position resolution.

  The ion filter 1 of the present embodiment has a function of collecting positive ions generated along with electron amplification so as not to move in the drift region DR side (in the direction opposite to the moving direction E of electrons).

  The ion filter 1 of the present embodiment includes an insulating base, a first conductive layer formed on one main surface of the insulating base, and a second conductive formed on the other main surface of the insulating base. It has a layer and a plurality of through holes formed along the thickness direction of the insulating substrate.

FIG. 2A, FIG. 2B, FIG. 2C, and FIG. 2D are figures which show typically an example of the ion filter 1 of this embodiment.
FIG. 2A is a perspective view of the ion filter 1 of the present embodiment, and FIG. 2B is a plan view of the ion filter 1 of the present embodiment. As shown to each figure, the ion filter 1 of this embodiment is provided with the through-hole 30. As shown in FIG. A rim 20 is formed between adjacent through holes 30. The through hole 30 is surrounded by the rim 20. The rim 20 constitutes the inner wall of the through hole 30. The through hole 30 forms an opening 31 along the main surface of the ion filter 1.

  The ion filter 1 of the present embodiment functions to collect positive ions that are fed back and not to move to the drift region DR, but on the other hand has a restriction that it must not prevent the movement of electrons. For this reason, in order to utilize as an ion filter 1, it is calculated | required that the aperture ratio of the through-hole 30 is a structure with high thickness and thin thickness.

  Although not particularly limited, in the ion filter 1 of the present embodiment, the aperture ratio of the through holes 30 is 65% or more, preferably 70% or more, and more preferably 75% or more. In the present embodiment, the aperture ratio of the through hole 30 is a ratio of the total area of the opening 31 formed by the through hole 30 to a predetermined unit area along the main surface of the insulating base material. A unit area for calculating the aperture ratio can be arbitrarily defined. The opening 31 is a two-dimensional area along the main surface of the ion filter without the insulating base and the conductive layer. The shape of the opening 31 of the through hole 30 of the present embodiment is substantially hexagonal. The ion filter 1 of the present embodiment has a so-called honeycomb structure.

  Moreover, the space | interval of the rim | limb 20 and the rim | limb 20 which comprise the through-hole 30 of this embodiment is 140 [micrometers]-300 [micrometers] or less. Further, the width of the rim 20 (the distance between the inner walls of the through holes 30) is 50 μm or less, preferably 40 μm or less.

  According to the simulation performed by the inventors, the aperture ratio of the opening 31 of the through hole 30 of the ion filter 1 is 70 in order to prevent movement of electrons, that is, to function as the ion filter 1. It turned out that it is desirable to be% or more. Moreover, according to the simulation conducted by the inventors, it is desirable that the thickness of the insulating base material 11 of the ion filter 1 is 25 [μm or less] in order to prevent the movement of electrons. all right. In the present embodiment of the present invention, an ion filter 1 satisfying these conditions is provided.

  Incidentally, the ion filter 1 of this embodiment is disposed on the upstream side (electrode 5 side, drift region DR side) of the gas electron amplifier 2 that amplifies electrons, as a member different from the gas electron amplifier 2. The ion filter 1 of the present embodiment is used for the purpose of collecting positive ions generated along with the electron amplification, which is different from the gas electronic amplifier 2, and exhibits a function different from the gas electronic amplifier 2.

  In the present embodiment, the ion filter 1 is disposed on the upstream side of the gas electron amplifier 2 (the side provided with the electrode 5, the side provided with the drift region DR) in the moving direction E of electrons. That is, the ion filter 1 is disposed between the gas electron amplifier 2 and the electrode 5. By arranging the ion filter 1 in this manner, the positive ion group generated in the gas electron amplifier 2 is collected by the ion filter 1 and the positive ion to be fed back is prevented from affecting the entire drift region DR. . This makes it possible to make drift electrons less susceptible to the influence of positive ions.

  The ion filter 1 of the present embodiment is juxtaposed to the gas electronic amplifier 2 provided in the TPC 100. The gas electron amplifier 2 may be a flat plate-like electron amplification foil or may have a different structure as long as it can amplify electrons.

FIG. 2C is a view showing an example of a cross section along line IIC-IIC shown in FIG. 2B of the ion filter 1 of the present embodiment.
As shown to FIG. 2C, the ion filter 1 of this embodiment is the 1st conductive layer pattern 12 formed in one main surface of the insulating base material 11, and the 2nd conductive layer pattern 13 formed in the other main surface. And The first conductive layer pattern 12 and the second conductive layer pattern 13 are applied to a preset potential. The first thickness th1 of the first conductive layer pattern 12 and the second thickness th2 of the second conductive layer pattern 13 formed on the other main surface may have the same thickness or different thicknesses.

  Although not particularly limited, the first thickness th1 of the first conductive layer pattern 12 is 8 μm to 15 μm, preferably 10 μm, and preferably 12 μm or less. . The second thickness th2 of the second conductive layer pattern 13 is 8 μm to 15 μm, and preferably 12 μm or less. The thickness of the first conductive layer pattern 12 and the second conductive layer pattern 13 in the present embodiment is 10 μm.

FIG. 2D is an enlarged view of an IID region surrounded by a broken line in FIG. 2C in the ion filter 1 of the present embodiment.
As shown in FIG. 2D, the insulating substrate 11 of the ion filter 1 of the present embodiment has a part or a plurality of voids 11a in its inside. There is no material (substance) constituting the insulating base 11 inside the holes 11a. Inside the holes 11a of the insulating base material 11 of the present embodiment, a detection gas, air, and other gases with which the chamber CB is filled are present. The holes 11a of the insulating base material 11 have an inner wall 11b that forms an interface with a gas. A gas is present in the space surrounded by the inner wall 11b, that is, inside the hole 11a.

  By the way, in order to improve the measurement accuracy when measuring the properties of one particle by integrating the measurement values obtained from a plurality of measuring devices as in the International Linear Collider (ILC) experiment, It is necessary to reduce the influence of the multiple coulomb scattering that the particles to be measured receive when passing through each measuring instrument.

The scattering angle of this multiple coulomb scattering is expressed by the following equation (Equation 1).

Moreover, the reaction cross-sectional area is represented by a following formula (Equation 2).

  That is, in order to reduce the influence of multiple coulomb scattering, in each of the parts constituting each measuring instrument, a material of a substance having a small atomic number is used, or the substance mass (amount of substance used) of each measuring instrument itself is low. It is necessary to design.

The particle collision point measuring device used for the International Linear Collider (ILC) experiment has a plurality of measuring devices such as TPC100. Specifically, a vertex detector, TPC 100, a calorimeter, and a muon detector (mu particle detector) are disposed as measuring devices with which the particle collision point measuring device is provided. Each measuring instrument may use the measurement principle of gas detection, or may use another measurement principle. The TPC 100 of this embodiment uses the measurement principle of gas detection.
The vertex detector is placed at the position closest to the particle generation point, that is, the most central side. The TPC 100 is installed outside the vertex detector. The TPC 100 of this embodiment uses a gas detector. One or more calorimeters are installed outside the TPC 100. A muon detector (mu particle detector) is installed outside the calorimeter. The arrangement of the measuring instrument group is not particularly limited, and may be changed according to the particles to be observed.

  As described above, the TPC 1001 including the gas electron amplifier 2 of the present embodiment and the ion filter 1 is disposed at the second closest position to the particle generation point. Since the particles to be observed move outward from the particle generation point, the multiple coulombs scattering generated in the internally disposed measuring device among the plurality of measuring devices is measured by the externally disposed measuring device. Affect the results.

In order to reduce the influence of the multiple coulomb scattering, in particular, it is required to reduce the object mass of a gas detector such as TPC 100 disposed relatively inward among the measuring devices of the particle collision point measuring device.
In the present embodiment, the holes 11 a are formed in the inside of the insulating base material 11 which is one configuration of the ion filter 1 provided in the TPC 100. By reducing the amount of substance of the ion filter 1, the amount of substance of the TPC 100 can be reduced. As a result, multiple coulombs of scattering that the particles to be observed pass through measuring instruments such as a calorimeter and a muon detector installed outside the TPC 100 (gas detector) (in the direction away from the particle generation point) Can reduce the effects of

  According to the above idea, the ideal structure of the ion filter 1 has a predetermined space (10 to 30 μm) without arranging two conductive layers in which a predetermined pattern is formed between them. ] Is a structure to arrange oppositely, keeping uniform.

  However, the sensitive area of the ion filter 1 used for TPC100 is 170 [mm] x 220 [mm], and the thickness of a conductive layer is about 8 [micrometers]-15 [micrometers]. Furthermore, in the conductive layer of the ion filter 1, an opening 31 of a honeycomb pattern is formed. It is extremely difficult to support such a thin, non-rigid conductive layer while maintaining a predetermined distance (10 to 30 μm). Moreover, in order to function as the ion filter 1, it is necessary to match the positions of the patterns of the two conductive layers, that is, the positions of the openings 31. It is more difficult to support a pair of conductive layers whose width is equal to or less than 50 μm, with a predetermined distance kept.

  In order to realize a structure in which the pair of conductive layers are arranged opposite to each other in a state where the positions of the patterns of the conductive layers coincide with each other while keeping a predetermined distance uniform, insulation according to the distance between the pair of conductive layers Base material needs to be provided between the conductive layers. When the insulating substrate is disposed to support the conductive layer in this manner, the amount of substance increases by the amount of the insulating substrate. That is, the influence of the multiple coulomb scattering increases by the amount of the insulating base material.

  To address this problem, in the present embodiment, one or more holes 11a are formed inside the ion filter 1, and the amount of substance is reduced by the amount of the holes 11a. Thereby, the ion filter 1 can be provided in which the substance mass of the insulating base material 11 is reduced by an amount according to the volume contained by the holes 11a. Thus, it is possible to provide the ion filter 1 capable of suppressing the influence of the multiple coulomb scattering while supporting the first conductive layer pattern 12 and the second conductive layer pattern 13 at predetermined positions.

  The thickness of the insulating base material 11 of the ion filter 1 of the present embodiment is preferably 10 μm to 30 μm, and more preferably 12 μm to 25 μm. Is preferred. The thickness of the insulating base material 11 of this embodiment is 12.5 [μm].

  In the ion filter 1 of the present embodiment, the first conductive layer pattern 12 is any one or more substances in the group consisting of copper, nickel, gold, tungsten, zinc, aluminum, chromium, tin, and cobalt. It is formed from the material which it contains. The second conductive layer pattern 13 is formed of a material including any one or more materials in the group consisting of copper, nickel, gold, tungsten, zinc, aluminum, chromium, and cobalt.

  Although not particularly limited, in the ion filter 1 of the present embodiment, the first conductive layer pattern 12 and the second conductive layer pattern 13 are both formed of a material mainly containing copper. Copper is easy to process, suitable for producing a thin rim 20 and a pattern with a high aperture ratio as in this embodiment, and is easy to obtain.

  Although not particularly limited, the thickness of the first conductive layer pattern 12 is 8 μm to 15 μm, preferably 12 μm or less, and more preferably 10 μm or less. The thickness of the second conductive layer pattern 13 is 8 μm to 15 μm, preferably 12 μm or less, and preferably 10 μm or less. The thickness of the first conductive layer pattern 12 and the second conductive layer pattern 13 in the present embodiment is 10 μm.

  Next, based on FIG. 3, the manufacturing method of the ion filter 1 of this embodiment is demonstrated. In FIG. 3, in order to make a manufacturing process intelligible, it represented by the end elevation.

  First, as shown in FIG. 3A, the first conductive layer 12A is formed on one main surface (upper side surface in the drawing) of the insulating base material 11A, and the second conductive layer 12A is formed on the other main surface (lower side surface in the drawing). The base 10A on which the conductive layer 13A is formed is prepared. In the present embodiment, a base material 10A having a thickness of 12 [μm] or more and 25 [μm or less] is used. In the present embodiment, the thickness th1 ′ of the first conductive layer 12A is preferably about 12 μm or less, and the thickness th2 ′ of the second conductive layer 13A is also preferably about 12 μm or less . Although not particularly limited, the thickness th1 ′ of the first conductive layer 12A in the present embodiment is equal to the thickness th2 ′ of the second conductive layer 13A. Although not particularly limited, in the present embodiment, the substrate 10A in which the thickness th1 ′ of the first conductive layer 12A is about 10 μm and the thickness th2 ′ of the second conductive layer 13A is also about 10 μm Use

  The insulating base 11A shown in FIG. 3A corresponds to the insulating base 11 of the ion filter 1, the first conductive layer 12A corresponds to the first conductive layer pattern 12 of the ion filter 1, and The second conductive layer 13 A corresponds to the second conductive layer pattern 13 of the ion filter 1.

  As shown in FIG. 3B, a predetermined region of the first conductive layer 12A is removed using a known photolithography technique to form a first conductive layer pattern 12 of a predetermined pattern. The predetermined pattern in the present embodiment is a honeycomb pattern. In the present embodiment, it is preferable to form the line width of the first conductive layer pattern 12 to 15 μm or more and 45 μm or less. The line width of the first conductive layer pattern 12 in the present embodiment is 30 μm or less.

  Next, moisture is included in the inside of the insulating base 11A of the base 10A on which the first conductive layer pattern 12 is formed. The method for including water inside the insulating base material 11A is not particularly limited, but in the present embodiment, as shown in FIG. 3C, the base material 10A is kept in the constant humidity tank 300 for a predetermined time or more. Moisture is contained in the inside of insulating base material 11A by leaving still in a store. The constant humidity tank 300 has a function of maintaining the environment in the tank, which is a closed space, at a constant temperature and a constant humidity.

  Although the invention is not particularly limited, in the present embodiment, the environment in the storage is managed such that the humidity in the storage of the constant humidity tank 300 becomes higher than the humidity in the standard temperature and humidity state, and By placing the material 10A, the interior of the insulating base material 11A is made to contain water. Standard temperature and humidity conditions follow the definition of ISO 554-1976 (Standard atmospheres for conditioning and / or testing-Specifications) or IEC Publication 160-1963 (Standard atmospheric conditions for test purposes). Specifically, the standard temperature and humidity state in the present embodiment is a temperature of 23 ° C. and a relative humidity of 50%. That is, in this embodiment, when the temperature inside the constant humidity tank 300 is 23 ° C., the relative humidity is set higher than 50%.

  Moreover, although it does not specifically limit, in this embodiment, the temperature in the inside of the constant humidity tank 300 is 23 degreeC-28 degreeC, and it managed so that relative humidity RH might be 80% RH-85% RH. Here, the relative humidity RH is a ratio (percentage) of the actually measured amount of water vapor when the amount of saturated water vapor at a predetermined temperature is 100. Then, the base material 10A was left for 24 hours in a state in which the constant humidity tank 300 was stored. After 24 hours, the weight of the base material 10A removed from the inside of the constant humidity tank 300 became heavier than the weight before being put into the constant humidity tank 300. Thus, it was confirmed that water could be contained in the inside of the insulating base 11A of the base 10A.

  Water may be atomized and sprayed onto the substrate 10A as a method of containing water inside the insulating substrate 11A of the substrate 10A, or the substrate 10A may be immersed in a water reservoir. .

  After water is contained in the inside of the base material 10A insulating base material 11A, the part corresponding to the predetermined region in the insulating base material 11A is removed. As shown in FIG. 3D, the base 10A is irradiated with a UV-YAG laser having a wavelength of 500 nm or less from the one main surface (upper side surface in the drawing) on which the first conductive layer pattern 12 is formed. For example, the substrate 10A is irradiated with a UV-YAG laser of the third harmonic (wavelength 355 [nm]). The first conductive layer pattern 12 of the predetermined honeycomb pattern formed earlier serves as a mask for the laser irradiated from the one main surface side, and the insulating property of the region corresponding to the predetermined region (a hexagonal region in this example) Only the substrate 11A is removed.

  When water is contained in the base material 10A and the base material 10A containing water is irradiated with a laser, water generated inside the insulating base material 11A is bumped by heat generated at the time of laser irradiation. Due to the phenomenon of bumping, a void 11a is generated inside the insulating base 11A. As a result, the holes 11a can be formed inside the insulating base material 11A.

  Subsequently, desmear processing such as plasma desmear processing is performed. The method of the desmear process uses the method known at the time of application suitably according to the method of removal of insulating substrate 11A.

  Finally, the etchant is applied from both sides of the substrate 10A (FIG. 3D) from which the predetermined region of the insulating substrate 11A has been removed. The etching solution used in the present embodiment is a mixed solution of sulfuric acid and hydrogen peroxide. The etching solution acts from the one main surface side of the second conductive layer 13A formed on the other main surface side of the base 10A, and also acts from the other main surface side of the second conductive layer 13A. That is, in the base 10A from which the predetermined area of the insulating base 11A is removed, the portion corresponding to the predetermined area of the second conductive layer 13A is etched from both sides. For this reason, the etching rate of the portion corresponding to the predetermined region of the second conductive layer 13A is approximately twice the etching rate of the portion corresponding to the region other than the predetermined region. At the timing at which the region corresponding to the predetermined region of the second conductive layer 13A is removed, the region corresponding to other than the predetermined region of the second conductive layer 13A remains.

  As a result, as shown in FIG. 3E, the second conductive layer pattern 13 is formed in which only the region corresponding to the predetermined region of the second conductive layer 13A is removed. The through hole 30 penetrating from the one main surface side to the other main surface side can be formed. Thereby, the ion filter 1 which comprises a predetermined pattern (for example, honeycomb pattern) can be obtained. In the present embodiment, it is preferable to form the line width of the second conductive layer pattern 13 in the range of 15 μm to 45 μm. The line width of the second conductive layer pattern 13 in the present embodiment is 30 [μm] or less. FIG. 2D described above is also an enlarged view of a portion shown by a broken line IID shown in FIG. 3E.

  Although it is an example, the thickness th1 'of the first conductive layer 12A shown in FIG. 3A is about 12.0 [μm], and the thickness th2' of the second conductive layer 13A is about 12.0 [μm] When the ion filter 1 of the present embodiment is manufactured using the base material 10A of the above, the thickness th1 of the first conductive layer pattern 12 is 10 μm, and the thickness th2 of the second conductive layer pattern 13 is 10 μm. ] Ion filter 1 was produced.

  It is not easy to form the through hole 30 having an aperture ratio of 75% or more and the rim 20 forming the through hole 30 in a thin sheet. The exposure accuracy causing the shift of the etching pattern in the photolithography technique at the time of the present application application is about +/− 10 [μm]. In addition, it is difficult to accurately etch a predetermined region of the insulating substrate 11A of the substrate 10A, and for example, a slope occurs in the etching process of polyimide. As described above, it is difficult to form a pattern having the same shape at the same xy position of the first conductive layer 12A and the second conductive layer 13A of the base 10A and to form a through hole along the z direction. Moreover, in order to set the aperture ratio of the first conductive layer 12A and the second conductive layer 13A to 75% or more, the width of the rim 20 is required to be 40 μm or less. Thus, it has not been easy to form the ion filter 1 that satisfies many conditions.

  In the known photolithography technology, the etching process is performed only from the one main surface side of the substrate 10A. According to the manufacturing method of the present embodiment, the through holes 30 are formed by removing only a predetermined region of the second conductive layer 13A on the other main surface side by simultaneously performing the etching process from both main surface sides of the base material 10A. Do. Since the known photolithography technology is not used, the problem of the shift of the etching pattern caused by the limit of the exposure accuracy does not occur. Thereby, the ion filter 1 in which the through-hole 30 was formed based on this embodiment can be produced. According to this manufacturing method, the aperture ratio of the through hole 30 can be 70% or more. Further, when the second conductive layer 13A on the other main surface side is etched, the step of forming a resist for pattern formation can be omitted.

  According to simulations by the inventors, when TPC 100 provided with the ion filter 1 of the present embodiment is disposed in an ILD (International Large Detector), it is disposed outside the TPC 100 (in a direction away from the particle generation point) in ILD. It has been confirmed that the measurement accuracy is improved in a calorimeter and other measuring instruments such as muon detectors. As described above, by using the ion filter 1 with a reduced amount of substance for TPC 100, which is one ILD measuring device, to reduce the influence of multiple coulomb scattering on particles (observation object) passing through the measuring device. it can.

  The embodiments described above are described to facilitate the understanding of the present invention, and are not described to limit the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents that fall within the technical scope of the present invention.

100 ... gas detector, TPC
DESCRIPTION OF SYMBOLS 1 ... Ion filter 11 ... Insulating base material 12 ... 1st conductive layer pattern 12A ... 1st conductive layer 13 ... 2nd conductive layer pattern 13A ... 2nd conductive layer 20 ... Rim 30 ... Through-hole 2 ... Gas electron amplifier, electron Amplifying foil 3 ... detection electrode 4 ... measuring instrument 5 ... electrode 300 ... constant humidity tank CB ... chamber DR ... drift region E ... moving direction of electrons

Claims (6)

An ion filter for use in a gas detector comprising a gas electronic amplifier, comprising:
An insulating base material,
A first conductive layer pattern formed on one main surface of the insulating substrate;
A second conductive layer pattern formed on the other main surface of the insulating substrate;
And a plurality of through holes formed along the thickness direction of the insulating substrate,
The said insulating base material is an ion filter which has one or several void | hole in the inside of the said insulating base material.   The opening ratio of the through holes, which is a ratio of the total area of the openings formed by the through holes to a predetermined unit area along the main surface of the insulating substrate, is 70% or more. Ion filter.   The ion filter according to claim 1, wherein a line width of the first conductive layer pattern and a line width of the second conductive layer pattern are 40 μm or less. A substrate comprising: an insulating substrate; a first conductive layer formed on one main surface of the insulating substrate; and a second conductive layer formed on the other main surface of the insulating substrate The step of preparing
Removing a predetermined region of the first conductive layer of the substrate to form a first conductive layer pattern of a predetermined pattern;
Including moisture inside the insulating substrate;
Removing a region corresponding to the predetermined region of the insulating substrate by irradiating a laser from the one main surface side;
Applying an etching solution from at least one main surface side of the base material from which the predetermined area has been removed to remove an area corresponding to the predetermined area in the conductive layer formed on the other main surface; The manufacturing method of the ion filter which it has.   5. The process according to claim 4, wherein the step of including water inside the insulating substrate is a step of placing the substrate under an environment controlled so that the humidity is higher than the humidity in the standard temperature and humidity condition. Method of manufacturing ion filter.   In the step of including water in the interior of the insulating substrate, the substrate is allowed to stand for a predetermined time or more in a chamber of a constant humidity tank controlled to have a relative humidity of 80% RH to 85% RH. The manufacturing method of the ion filter of Claim 4 or 5 which is a process.