JP2005032634A - Gas proportional counter tube and photographing system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas proportional counter tube and a photographing system in which impact resistances and handling natures of an electron and an optical multiplication part can be improved and a fine pores can be made uniform, and the uniformity of sensitivity distribution can be improved. <P>SOLUTION: A photographing type X ray detection device 200 has a photographing system 210 connected to a power supply system 34 and a control system 35. In the photographing system 210, a chamber 23 having a CMOS sensor array is jointed through an FOP2 to the rear stage of a chamber 22 which has a beryllium aperture 21 and is provided with a porous plate 1 having a numerous number of hollow filaments 13 provided side by side. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a gas proportional counter and an imaging system.

  In recent years, a new type of detector that operates a lead glass capillary plate as an imaging type gas proportional counter (CGPC) has been developed (see Non-Patent Documents 1 and 2). FIG. 7 is a schematic diagram showing a configuration of an imaging X-ray detection apparatus using such CGPC (see Non-Patent Document 3).

  In the figure, the imaging X-ray detection apparatus 100 is configured such that an optical system 120 and an imaging system 130 are connected in sequence at the subsequent stage of the gas proportional counting unit 110. The gas proportional counting unit 110 includes a capillary plate provided coaxially with the windows 111 and 112 in a chamber 113 provided with a beryllium window 111 and a light transmission window 112 made of synthetic silica at one end and the other end, respectively. 114 is installed. The capillary plate 114 is formed by integrating a plurality of hollow lead glass capillaries having a diameter of about 100 μm, and the bias angle at the time of molding is 0 °.

Thin film electrodes (not shown) connected to the power supply system 140 are formed on both surfaces of the capillary plate 114. Further, shaping rings (shaping rings) 115 and 116 are provided in the front stage of the capillary plate 114, and a drift region is defined. These shaping rings 115 and 116 are connected to the power supply system 160 and the ground potential, and a high voltage from the power supply system 160 and the ground are resistance-divided so that an appropriate drift voltage is applied to each. Yes. Further, in the chamber 113, a mixed gas 117 in which trimethylamine (TMA) or triethylamine (TEA) having a Penning Effect is added to Ar gas, CH ₄ gas, or the like as main components is enclosed.

  In this imaging X-ray detection apparatus 100, X-rays A entering the chamber 113 through the beryllium window 111 interact with gas molecules in the region between the beryllium window 111 / capillary plate 114, and high-energy electrons (primary Electrons) are emitted. The primary electrons (X-ray photoelectrons) travel while applying energy to other gas molecules, and generate electron-ion pairs in the tracks. Therefore, the number of electron-ion pairs is proportional to the energy of X-ray A. Electrons (also called electron clouds) generated along the tracks of primary electrons are generated from the front surface of the capillary plate 114 while maintaining the shape of the electron cloud by an electric field generated between the beryllium window 111 / capillary plate 114. Enter.

An electric field of, for example, 10 ⁴ V / cm or more sufficient to cause gas discharge and excitation light emission is formed inside the capillary plate 114, and electrons collide with gas molecules one after another to cause electron proliferation and photoproliferation. For example, one electron is amplified to about 10 ³ to 10 ⁴ . In this way, the imaging X-ray detection apparatus 100 functions as a gas proportional counter. The amplified light passes through the light transmission window 112 and enters the optical system 120, passes through the lens system 121, passes through the light transmission window 122 made of magnesium fluoride (MgF ₂ ), etc., and is emitted to the imaging system 130.

  As the imaging system 130, for example, an ICCD (Intensified CCD) is employed. Incident light is photoelectrically converted by a photocathode (not shown). I. After the electron multiplication at 131, it is photoelectrically converted again by a phosphor screen (not shown) and enters a CCD array (both not shown) through a fiber optic plate (FOP) or the like. The enhanced two-dimensional image information is sent to the signal processing system 150 as an electric signal, and for example, a three-dimensional X-ray emission image composed of the two-dimensional position information and the emission intensity at each position is obtained.

In addition, those using a reflection system (reflector) instead of the lens system 121 and those equipped with a photomultiplier tube (PMT) instead of the optical system 120 and the imaging system 130 have been developed. (See Non-Patent Documents 4 to 8.) In addition, in order to suppress the charge-up of the capillary plate, instead of the capillary plate 114, a material in which the inner surface of the through hole is reduced by H _{2 to} reduce the resistance like the MCP has been proposed (see Non-Patent Document 9).

  Furthermore, recently, as another radiation detector capable of detecting a two-dimensional position of X-rays or the like, a gas electron multiplier (GEM) has attracted attention (for example, Non-Patent Document 10, 11).

  FIG. 8 is a schematic plan view showing a part of a porous polyimide film generally used for GEM. FIG. 9 is a sectional view taken along line IX-IX in FIG. The porous polyimide film 411 is a thin film (for example, a thickness of several tens of μm) in which a plurality of pores 413 are formed at regular intervals using a method combining laser lithography and dry etching or wet etching, for example. ˜100 μm).

As a general shape of the pore 413, for example, as shown in FIG. 8 and FIG. 9, it has a substantially cylindrical shape, and a protrusion K is formed near the center in the thickness direction of the porous polyimide film 411. Things. Further, typical dimensions of the pores 413 include a maximum inner diameter of about 50 to 100 μm, a minimum inner diameter (that is, an inner diameter of the protrusion K) of about −10 μm of the maximum inner diameter, and a pore interval of about 100 to 200 μm. . When used for GEM, the in-plane density of the pores 413 is, for example, on the order of 10 ⁴ / cm ² .

In the GEM using such a porous polyimide film 411, a voltage of several hundred volts is applied between electrodes made of metal layers deposited on both surfaces of the film 411, and gas discharge is generated in and around the pores 413. And an electric field sufficient to cause excitation emission is formed. Thereby, electrons collide with gas molecules one after another, and electron multiplication is performed.
H. Sakurai et al., "A new type of proportional counter using a capillary plate", Nucl. Instr. And Meth. In Phys. Res. A374 (1996) 341-344. H. Sakurai et al., "Characteristics of capillary gas proportional counter", SPIE Proceedings Reprint, vol. 2806 (1996) 569-576. H. Sakurai et al., "Detection of photoabsorption point with capillary imaging gas proportional counter", IEEE Trans on Nucl. Sci. Vol. 49, No. 3, (2002). M. Tsukahara et al., "The development of a new type of imaging X-ray detector with a capillary plate", IEEE Trans on Nucl.Sci.vol.49, No.3, (1997) 679-682. H. Sakurai et al., "The form of X-ray photoelectron tracks in a capillary gas proportional counter", IEEE Trans on Nucl.Sci.vol.46, No.3, (1999) 333-337. H. Sakurai, "Imaging gas proportional counter with capillary plate", Radiation vol.25, No.1, (1999) 27-37. H. Sakurai et al., "New type of imaging X-ray detector using a capillary plate", SPIE Proceedings Reprint, vol. 3114 (1997) 481-487. T. Masuda et al., "Optical imaging capillary gas proportional counter with penning mixture", IEEE Trans on Nucl.Sci.vol.49, No.2, (2002) 553-558. Nishi, Yu .; Tanimori, Y .; Ochi, A .; Nishi, Ya .; Toyokawa, H., "Development of a hybrid MSGC with a conductive capillary plate.", SPIE, vol.3774 (1999) 87-96 . F. Sauli, Nucl. Instr. And Meth. A 368 (1977) 531. FAF Fraga et al., Nucl. Instr. And Meth. A 442 (2000) 417.

  However, when the present inventors examined in detail the imaging X-ray detection apparatus 100 using the above-described conventional CGPC and the GEM including the porous polyimide film 411, the following problems exist. I found it.

  In the imaging X-ray detection apparatus 100, in order to form a high electric field at a low voltage, it is desirable that the capillary plate 114 has a thickness of about 60 to 70 μm at most. For this purpose, a glass plate is mechanically polished. There is a need to. However, when a glass plate is polished thinly in this way, the glass itself is hard and brittle, so that it tends to crack and peel off, and is sensitive to mechanical shock, so it needs to be handled with great care.

  Further, the thin film electrodes provided on both surfaces of the capillary plate 114 are deposited by vapor deposition or the like, but there are cases where the adhesion between the capillary plate 114 and the thin film electrode is insufficient, and this makes the electrode easy to peel off. Inconvenience arises. Furthermore, it was confirmed that dark current and sudden abnormal current are generated in the lead glass capillary plate 114 due to the α-ray background emitted from the radioactive lead nuclide contained in the material.

  On the other hand, in the GEM provided with the porous polyimide film 411, since the polyimide film is subjected to hole processing, depending on the method used, processing failure, that is, the film is not sufficiently penetrated, and part of the pores 413 is not formed or penetrated. However, the pores 413 having a desired shape may not be obtained. In addition, it may be difficult to form uniform pores 413 at regular intervals. If this happens, the two-dimensional sensitivity distribution may become non-uniform in the porous polyimide film 411.

  Furthermore, although it is unclear whether the shape of the pores 143 having a spire-like inner wall as shown in FIG. 9 is inconvenient or not, the position of the protrusion K and the cross-sectional shape in the thickness direction are different for each pore 143. There is concern that it will be uneven. When this happens, a difference occurs in the electric field in each pore 143, and in some cases, it cannot be said that there is no possibility that the uniformity of the sensitivity distribution in the porous polyimide film 411 is disturbed.

  Therefore, the present invention has been made in view of such circumstances, and even if the electron and photomultiplier portions are thinned, the impact resistance and handling properties can be improved, and the uniformly and uniformly disposed fine cells can be improved. An object of the present invention is to provide a gas proportional counter and an imaging system capable of realizing an electron and a photomultiplier having holes and thereby improving the uniformity of sensitivity distribution.

  In order to solve the above problems, a gas proportional counter according to the present invention includes a chamber filled with a detection gas containing an inert gas as a main component and having a window through which electromagnetic waves or ionizing radiation is incident, and the chamber. And a plurality of pipes made of resin are provided in parallel with each other in a direction intersecting the axial direction of the pipes.

  In the gas proportional counter tube thus formed, a plurality of tubes constituting a plate-like body are provided side by side to form a member in which a plurality of holes are uniformly arranged at regular intervals. Therefore, when a constant voltage is applied to both surfaces of the plate-like body, an electric field sufficient to cause gas discharge and excitation light emission can be formed in and around the hole. Since these holes are preliminarily formed by hollow tubes, there is no possibility of causing processing defects that are a concern when the holes are processed in the membrane. Moreover, since these several pipe | tubes consist of resin, a plate-shaped body is rich in a softness | flexibility. Therefore, unlike a glass plate such as a capillary plate, cracking and peeling are unlikely to occur.

  Furthermore, since the plate-like body made of resin does not substantially contain a radiation source such as a natural radionuclide, abnormal discharge (for example, alpha rays emitted from the lead nuclide can be caused by a capillary plate made of lead glass). The resulting discharge cannot occur.

  Specifically, the tube is preferably made of a hollow fiber. A hollow fiber constitutes an extremely thin tube, and a plate-like body in which a plurality of these are provided side by side has a large number of pores arranged uniformly at very narrow intervals. Forming a plate-like body with hollow fibers includes a method of bundling a large number of hollow fibers into a bundle and slicing them, and such processing is also simple.

  More specifically, the resin is more preferably a polyolefin. These are not only easily available as hollow fibers, but also exhibit a relatively high resistivity (volume resistivity) among resin materials, so that they are vapor-deposited on both sides when the plate-like body is made extremely thin. The insulation between the electrodes can be sufficiently secured, and the formation of the electric field can be made more reliable. In addition, since the resistance is not excessively high enough to easily accumulate charges during long-term use, the occurrence of an abnormal sudden current due to charge-up is prevented.

  Preferably, it is more useful if the resin is non-halogen, such as polyethylene or polypropylene. Resins composed of these materials exhibit sufficiently high resistivity as compared with halogen-based resins.

  Further, the detection gas preferably contains an organic gas containing a halogen atom in the molecule. By adding an organic gas containing a halogen atom as the detection gas, visible light can be emitted with high efficiency, so transmission loss can be suppressed even with a general optical system in the imaging system, and high sensitivity measurement Is possible.

In this case, the organic gas is more preferably a gas composed of a hydrocarbon in which at least one hydrogen atom is substituted with a fluorine atom (for example, a halogenated alkane such as CF ₄ ) from the viewpoint of light wavelength and light emission amount. According to the present knowledge of the present inventor, CF ₄ gas is considered to be most preferable in consideration of handleability and industrial applicability.

  The imaging system according to the present invention includes the gas proportional counter according to the present invention and a photodetector arranged at the rear stage of the chamber. The type of the photodetector is not particularly limited, and examples include a sensor using a CCD, PMT, anode board, CMOS, etc. Among these, a CMOS sensor that is easily arrayed and highly sensitive is particularly preferable. In addition, when a CMOS sensor is used, the imaging system can be made smaller than when a CCD or the like is used, and the time resolution at the time of imaging is greatly improved. There is an advantage that high-speed dynamic analysis can be achieved. Furthermore, when a CMOS sensor is used, there is an advantage that power consumption is remarkably reduced to, for example, half or less compared with the case where a CCD is used.

  According to the gas proportional counter and the imaging system of the present invention, the impact resistance and handling can be improved even if the plate-like body which is the electron and photomultiplier is thinned, and it is arranged uniformly and uniformly. A plate-like body having pores can be realized, and thereby the uniformity of sensitivity distribution can be improved.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same element and the overlapping description is abbreviate | omitted. Also, the positional relationship such as up / down / left / right is based on the positional relationship of the drawings.

  FIG. 1 is a plan view schematically showing a preferred embodiment of a plate-like body provided in a gas proportional counter according to the present invention, and FIG. 2 is a sectional view taken along line II-II in FIG. The perforated plate 1 (plate-like body) is a resin frame 12 in which a plurality of resin hollow fibers 13 (tubes) are arranged. The hollow fibers 13 are provided side by side so that their axial directions are along the thickness direction of the perforated plate, and the space 11 between the hollow fibers 13 is filled with the side walls of the hollow fibers 13. For example, another resin body (such as an adhesive) may be filled. Further, thin-film electrodes 1a and 1b formed by, for example, vacuum vapor deposition or the like are provided on both surfaces of the porous plate 1.

  With such a configuration, the perforated plate 13 is formed so that a large number of pores are aligned, and each hole is a fine channel constituting an independent photo / electron multiplier in the gas proportional counter. Function.

  That is, in the perforated plate 1, when a voltage is applied between the electrodes 1 a and 1 b, that is, both ends of the pores (channels) defined by the hollow fibers 13, an axial direction is formed inside and around the ends of the pores. An electric field is generated. At this time, when electrons generated in the upper part of the perforated plate 1 enter the channel from one end of the channel, the incident electrons are given energy from the electric field, and repeat ionization / excitation collisions with gas atoms in the channel. Electron / photomultiplication (growth) is performed by exponentially increasing photons accompanying de-excitation.

  Here, the resin material of the hollow fiber 13 constituting the perforated plate 1 is not particularly limited, but is preferably a polyolefin, and more preferably a non-halogen type, for example, polyethylene or polypropylene. . Moreover, those resins may or may not be crosslinked.

  The outer diameter of the perforated plate 1 (the outer diameter of the resin frame 12) and the effective outer diameter (the inner diameter of the resin frame 12) vary depending on various applications, and the pore diameter of the hollow fiber 13 and the desired position resolution. Although it is determined appropriately according to the above, it is usually set to about 1 to 100 mmφ. Furthermore, the thickness of the porous plate 1 is preferably about 0.05 to 2.0 mm. When the thickness of the porous plate 1 is less than 0.05 mm, sufficient film strength tends to be not obtained.

  Furthermore, the pore diameter in the porous plate 1, that is, the inner diameter of the hollow fiber 13 is usually about 6 to 100 μm. When the inner diameter of the hollow fiber 13 is less than this lower limit value, sufficient photo / electron multiplication characteristics tend not to be obtained. On the other hand, when the inner diameter of the hollow fiber 13 exceeds 100 μm, there is a possibility that the requirements such as high resolution, high speed response, and high resolution cannot be sufficiently satisfied, depending on the application.

  The gain characteristics of the perforated plate 1 depend on the ratio of the axial length L of the hollow fiber 13 to the inner diameter d of the hollow fiber 13 (standardized length a = L / d). It is effective to increase the standardized length a. However, if the standardized length a is excessively large, ion feedback is likely to occur due to collision between a gas (described later) and multiplier electrons existing in the pores. When this happens, noise tends to increase and the S / N ratio tends to decrease. Further, in the perforated plate 1, if the thickness exceeds about 1 mm, there is a concern that the increase in noise becomes significant as compared with the improvement in gain. Therefore, the upper limit of the normalized length a is about 200, for example. Is done.

  The method for producing the perforated plate 1 having such a configuration is not particularly limited, but for example, the following method can be used. First, the long bodies of the hollow fibers 13 are bundled to form a bundle, which is fixed in a long tube that becomes the resin frame 12 to obtain a block in which the hollow fibers 13 are arranged. Next, the perforated plate 1 can be easily obtained by slicing (slicing) the block to have a certain thickness.

  FIG. 3 is a perspective view (partially cutaway view) showing a preferred embodiment of an imaging system using a gas proportional counter of the present invention having a perforated plate 1. FIG. 4 is a cross-sectional view schematically showing the main part.

  The imaging X-ray detection apparatus 200 (imaging system) is configured such that a power supply system 34 and a control system 35 (also serving as a measurement circuit system) in which a CAMCA unit and a display device are incorporated are connected to an imaging system 210. . The imaging system 210 has a substantially cylindrical shape, the upper end of which is covered with a beryllium window 21 (window) and the side walls are provided with an exhaust port 22a and an intake port 22b, and the incident direction of X-rays Pv (electromagnetic waves). And a chamber 23 joined to the rear stage of the chamber 22.

  In the chamber 22, hollow shaping rings (shaping rings) 215 and 216 and the above-described perforated plate 1 are coaxially provided from the upstream side along the incident direction of the X-ray Pv. These shaping rings 215 and 216 are connected to the power supply system 34 and the ground potential, and the high voltage from the power supply system 34 and the ground are divided by resistance so that an appropriate drift voltage is applied to each of them. Yes. A drift region is defined in the front space of the perforated plate 1 by these shaping rings 215 and 216.

  The electrodes 1a and 1b of the perforated plate 1 are connected to a power supply system 34, respectively, and a predetermined cathode voltage is applied to the former to act as an anode, and a predetermined anode voltage functions as a cathode to the latter. .

Further, an opening is provided at the boundary between the chambers 22 and 23, and the FOP 2 is fitted and installed therein so as to seal the chamber 22 side. In the space in the chamber 22 thus closed, the main gas components such as He gas, Ar gas, Xe gas, CH ₄ gas, and the like preferably contain a halogen atom, more preferably a fluorine atom in the molecule. _An organic gas such as a halogenated alkane such as ₄ is added, and a detection gas 217 to which a quenching gas is added as necessary is enclosed. The detection gas 217 is appropriately exhausted and supplied using the exhaust port 22a and the intake port 22b.

The addition amount of an organic gas such as CF ₄ can be appropriately selected according to the type of gas, but is preferably about 1 to 10% by volume, more preferably several volume% with respect to the total amount of the detection gas 217. It is said. Thus, the proportional counter of the present invention is constituted by the beryllium window 21, the chamber 22, the shaping rings 215, 216, the perforated plate 1, and the detection gas 217.

  Further, a CMOS sensor array 3 (CMOS sensor; photodetector) is installed on the bottom wall of the chamber 23 coaxially with the perforated plate 1 and the FOP 2, and the CMOS sensor array 3 is driven around the CMOS sensor array 3. A drive circuit board 4 is provided. Furthermore, the above-described power supply system 34 is connected to the shaping rings 215 and 216 and the perforated plate 1 through the power supply terminals 24 provided on the side walls of the chamber 23, and the drive circuit board 4 and the power supply terminals 24 through the power supply terminals 24. Driving power is also supplied to the CMOS sensor array 3. Furthermore, the control system 35 is connected to the drive circuit board 4 via a signal terminal 25 provided on the side wall of the chamber 23.

  According to the thus configured gas proportional counter and imaging X-ray detection apparatus 200, X-rays Pv incident into the chamber 22 through the beryllium window 21 are converted into gas molecules in the region between the beryllium window 21 and the porous plate 1. Interaction occurs, and high energy electrons (primary electrons) are emitted by the photoelectric effect. The primary electrons (X-ray photoelectrons) travel while applying energy to other gas molecules, and generate electron-ion pairs in the tracks. Electrons (electron clouds) generated along the tracks of primary electrons enter the inside of the porous plate 1 from the front surface while maintaining the shape of the electron cloud by the electric field generated between the beryllium window 21 and the porous plate 1. .

An electric field of, for example, 10 ⁴ V / cm or more sufficient to cause gas discharge and excitation light emission is formed inside the perforated plate 1, and electrons collide with gas molecules one after another to cause electron proliferation and photoproliferation. For example, one electron is amplified to about 10 ³ to 10 ⁴ . At this time, various elementary reactions are caused, and in particular, when the excited CF ₄ molecule transitions to the ground state, light having a wavelength peculiar to the energy transition is emitted (CF ₄ ^* → CF ₄ + hν). . The wavelength region of this excitation light emission is wide from visible light to infrared light region, and its peak wavelength is about 620 nm.

  The shaping rings 215 and 216 are supplementarily used when the gas thickness between the beryllium window 21 and the porous plate 1 is increased to increase the X-ray detection efficiency. Although not shown, normally, the beryllium window 21 is grounded, and a voltage of about 10 to 200 V is applied immediately before the perforated plate 1 so that the electric field between the beryllium window 21 and the perforated plate 1 is, for example, 100 to 200 V / cm. It is adjusted to be about. At this time, if the distance between the beryllium window 21 and the porous plate 1 is increased, the electric field is likely to be disturbed. Therefore, the shaping rings 215 and 216 are used for the purpose of 'shaping' the electric field. Therefore, when the distance between the beryllium window 21 and the porous plate 1 is small without giving much importance to the X-ray detection efficiency, the shaping rings 215 and 216 may not be used.

  The amplified light passes through the FOP 2 and enters the CMOS sensor array 3 without being subjected to photoelectric conversion again. From the CMOS sensor array 3, an electrical signal based on the two-dimensional position information on which light is incident and the light intensity at each incident position is output to the control system 35 through the drive circuit board 4, where a three-dimensional X-ray emission image is formed. And output to a display device or the like.

  In the perforated plate 1 used in this way, since the tubular hollow fibers 13 are arranged uniformly, a state in which the pores are regularly arranged at regular intervals is generated. Therefore, the gas proportional counter of the present invention and the imaging X-ray detection apparatus 200 including the same are excellent in resolution as a two-dimensional position detector for detecting the incident position of radiation such as X-ray Pv. . Moreover, since the hollow fibers 13 are densely provided adjacent to each other, further high resolution can be expected.

  Further, since the pores formed in the perforated plate 1 are provided in the hollow fiber 13 in advance, there is no possibility of causing a processing defect which is a concern when the hole processing is performed on the membrane as in the conventional GEM. Therefore, it is possible to prevent the two-dimensional sensitivity distribution from becoming uneven in the porous plate 1. Further, since the pores are defined by the straight tubular hollow fiber 13, there is no protrusion K (see FIG. 9) in the thickness direction of the perforated plate 1 as seen in a conventional GEM. Therefore, unlike the GEM, which has a concern that the position and the cross-sectional shape of the protrusion K are not uniform for each pore, the electric field in each pore is made uniform, and the uniformity of the sensitivity distribution in the porous plate 1 is improved. be able to.

  Furthermore, since the hollow fiber 13 is made of a resin, it is not necessary to mechanically polish it as in a capillary plate using a glass plate, and it is not as hard and brittle as glass, and is rich in flexibility. No cracking or peeling can occur during the production of Furthermore, since it is strong against mechanical impact, it is difficult to be damaged during use by such external impact, and it is excellent in handleability. In addition, the perforated plate 1 is easy to manufacture, and can be thinned by slicing the block body as described above, for example. Therefore, it is easy to make the thickness thinner than about 70 μm, and it is easy to form a high electric field at a low voltage.

  Further, since the resin hollow fiber 13 constitutes the perforated plate 1, the adhesion of the thin film electrodes 1a and 1b deposited by vapor deposition or the like is enhanced as compared with the glass material. Therefore, peeling of the electrodes 1a and 1b can be sufficiently prevented, and the reliability of the apparatus is improved. Furthermore, since there is almost no possibility that the perforated plate 1 contains natural radionuclides, abnormal ionization current and abnormal light emission due to α-rays, which could be a problem with channel glass using conventional lead glass, can be reliably suppressed, The ground level can be significantly reduced. Therefore, the S / N ratio can be significantly improved, and thereby X-ray measurement with higher sensitivity and higher accuracy than before can be performed.

  Furthermore, when the hollow fiber 13 is made of polyolefin, particularly non-halogen polyolefin such as polyethylene or polypropylene, it has excellent industrial utility and moderately high resistivity, so that the porous plate 1 is made extremely thin. Even then, the insulation between the electrodes 1a and 1b can be sufficiently secured, and the formation of the electric field can be made more reliable. In addition, since the resistance is not excessively high enough to easily accumulate charges during long-term use, it is possible to prevent the occurrence of an abnormal sudden current due to charge-up.

Furthermore, when a gas to which an organic gas such as a halogen-substituted alkane such as CF ₄ gas is added as the detection gas 217, light having a wavelength in the visible region can be emitted with high efficiency. Even when a general-purpose FOP2 having excellent visible light transmittance is used, high transmittance can be achieved. Therefore, attenuation of the incident light to the CMOS sensor array 3 can be sufficiently prevented, and more sensitive X-ray measurement can be realized.

  FIG. 5 is a cross-sectional view schematically showing a main part of another embodiment of the imaging system using the gas proportional counter of the present invention including the porous plate 1. The imaging photodetection device 300 (imaging system) includes an imaging system 310 having an entrance window 31 instead of the beryllium window 21 and performs imaging measurement of light Px instead of X-ray Pv. Other than this, the configuration is the same as that of the imaging X-ray detection apparatus 200 shown in FIGS.

  The incident window 31 functions as a so-called transmission type photocathode. For example, a thin base metal film is formed on a window base material such as quartz, and further, for example, a bialkali compound, a multialkali compound, a bialkali, A photoelectron emission film 31a having a thin film made of an antimony or tellurium compound, a multi-alkali and an antimony or tellurium compound, or the like, and an intermediate layer made of carbon nanotubes or the like as required is formed by vapor deposition or the like.

In the imaging photodetection device 300 configured as described above, when the light Px incident on the incident window 31 reaches the photoelectron emission film 31a, the photoelectrons generated by the photoelectric conversion are emitted to the space in the front stage of the porous plate 1. This photoelectron corresponds to the primary electron described in the image-capturing photodetection device 200, generates an electron-ion pair in the same manner as described above, and performs electron multiplication and light amplification in the perforated plate 1, and CF ₄ gas. Excitation light emission is obtained. This light is amplified by the perforated plate 1, passes through the FOP 2 and enters the CMOS sensor array 3, and a three-dimensional incident light image is output to a display device or the like. The imaging photodetection device 300 also provides the same operational effects as the imaging X-ray detection device 200 described above (the description is omitted here to avoid duplication).

  In addition, this invention is not limited to each embodiment mentioned above, A various deformation | transformation is possible in the range which does not deviate from the summary. For example, the resin frame 12 in the perforated plate 1 may be omitted. In this case, at the time of manufacturing the perforated plate 1, a method of joining long bundles of bundled hollow fibers 13 with an adhesive resin can be employed. Further, the shape of the perforated plate 1 is not limited to a disc shape, and may be a square plate shape, for example. FIG. 6 is a perspective view schematically showing an example of another plate-like body used in the gas proportional counter of the present invention. The perforated plate 10 (plate-like body) includes a rectangular resin frame 212, a large number of hollow fibers 13 are provided, and the space 211 is embedded with, for example, another resin.

Furthermore, the gas for detection 217 may be added with another Penning effect gas such as TMA or TEA instead of or in addition to the CF ₄ gas, but the excitation light wavelength becomes visible as described above. In this respect, an organic gas such as a halogenated alkane such as CF ₄ is more preferable.

  Furthermore, in place of the CMOS sensor array 3, an imaging sensor using a CCD, ICCD, PMT, or anode board may be used. However, the CMOS sensor array 3 is used for high-definition and high-speed dynamic analysis. It is desirable. Further, a combination of the conventional light transmission window 112 and the optical system 120 may be used instead of the FOP2, or a bundle-shaped optical fiber may be used.

  As described above, if the gas proportional counter and the imaging system according to the present invention are used, impact resistance and handling can be improved even if the plate-like body which is an electron and a photomultiplier is thinned, and it is uniform. In addition, it is possible to realize a plate-like body having pores arranged uniformly, thereby improving the uniformity of the sensitivity distribution.

It is a top view which shows typically suitable one Embodiment of the plate-shaped object with which the gas proportional counter by this invention is equipped. It is the II-II sectional view taken on the line in FIG. 1 is a perspective view showing a preferred embodiment of an imaging system using a gas proportional counter of the present invention having a perforated plate 1. FIG. It is sectional drawing which shows typically the principal part of suitable one Embodiment of the imaging system using the gas proportional counter of this invention provided with the porous plate. It is sectional drawing which shows typically the principal part of other embodiment which concerns on the imaging system using the gas proportional counter of this invention provided with the porous plate. It is a perspective view which shows typically an example of the other plate-shaped object used for the gas proportional counter of this invention. It is a schematic diagram which shows the structure of the imaging type X-ray detection apparatus using the conventional CGPC. It is a schematic plan view which shows a part of porous polyimide film used for GEM. It is sectional drawing which follows the IX-IX line in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,10 ... Porous plate (plate-shaped body), 1a, 1b ... Electrode, 3 ... CMOS sensor array (photodetector), 4 ... Drive circuit board, 12, 212 ... Resin frame, 13 ... Hollow fiber (tube), DESCRIPTION OF SYMBOLS 21 ... Beryllium window, 22, 23 ... Chamber, 31 ... Incident window, 31a ... Photoelectron emission film, 34 ... Power supply system, 35 ... Control system, 200, 300 ... Imaging type X-ray detection apparatus (imaging system), 210, 310 ... Imaging system, 215, 216 ... Shaping ring, 217 ... Detection gas, Pv ... X-ray, Px ... Light.

Claims (7)

A chamber filled with a detection gas containing an inert gas as a main component and having a window through which electromagnetic waves or ionizing radiation is incident;
A plate-like body that is arranged in the chamber and in which a plurality of pipes made of resin are provided in a direction intersecting the axial direction of the pipes;
Gas proportional counter with.   2. The gas proportional counter according to claim 1, wherein the pipe is made of a hollow fiber.   The gas proportional counter according to claim 1, wherein the resin is polyolefin.   The gas proportional counter according to claim 1, wherein the resin is polyethylene or polypropylene.   The gas proportional counter according to claim 1, wherein the detection gas contains an organic gas containing a halogen atom in a molecule.   6. The gas proportional counter according to claim 5, wherein the organic gas is a gas composed of a hydrocarbon in which at least one hydrogen atom is replaced with a fluorine atom. A gas proportional counter according to any one of claims 1 to 6;
A photodetector disposed downstream of the chamber;
An imaging system comprising:

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