JP4742391B2 - Two-dimensional radiation and neutron image detector - Google Patents

Description

  The present invention relates to a detector for obtaining a two-dimensional radiation image using a scintillator and a phosphor as a radiation detector, and constitutes a scintillator having a short fluorescence lifetime and a detector combining a phosphor and a wavelength shift fiber. Therefore, even when radiation enters at a high incidence rate, it is characterized in that a two-dimensional radiation image can be detected at high speed and with high positional accuracy. In particular, two-dimensional neutron imaging combined with a neutron converter is also possible. For this reason, physical physics research and structural biology research such as neutron scattering using nuclear reactors and accelerators or X-ray scattering using synchrotron radiation, X-ray It is used for medical X-ray diagnosis using generators and accelerators, autoradiography using X-rays or neutrons, and the like. It is also used for grasping dynamic events using high-speed processing such as radiation image detectors for high-energy physics research using accelerators and real-time radiation image detection, and including neutrons in nuclear reactors and fusion reactors. It is also used for highly functional distribution monitoring devices for radiation.

  Conventionally, the fluorescence generated when radiation is incident on a scintillator or a phosphor is detected by using an optical fiber bundle such as a wavelength shift fiber arranged in a lattice form in the horizontal and vertical directions, and the incident position of the radiation is determined. Two-dimensional radiation image detectors using the method have been used. In the case of a detector using a scintillator, FIG. 31 (K. Kuroda et al .: Nucl. Instr. And Meth. A430 (1999) 311-320) or FIG. 32 (Katagiri Masaki: Japanese Patent Laid-Open No. 2000-187077) As shown in (2), since it is necessary to form one pixel with one scintillator, a relatively large scintillator is used. Therefore, a two-dimensional radiation image detector having a relatively large area with a position resolution of about 5 mm or more. Has been used.

  On the other hand, when a phosphor is used, detection is performed using an optical fiber bundle such as a wavelength shift fiber that is arranged in a grid in the horizontal and vertical directions using a thin fluorescent sheet. Since it is necessary to shorten the arrangement interval of the fiber bundle, it has been used for a two-dimensional radiation image detector having a relatively small area with a position resolution of about 2 mm or less.

  On the other hand, in the case of such a detector, a scintillator or a phosphor having a short fluorescence lifetime is used, and the generated fluorescence is detected using an optical fiber such as a wavelength shift fiber arranged in a lattice form in the horizontal and vertical directions. Therefore, the number of photons reaching the photodetector is several tens or less except for some phosphors such as ZnS: Ag having a large amount of fluorescence. For this reason, when radiation is incident, the fact that fluorescence is generated according to the Poisson distribution is utilized, the fluorescence from the wavelength shift fiber in the horizontal and vertical directions is photomultiplier tube, the amplification circuit for amplifying the signal, the signal K. Kuroda et al. (K. Kuroda et al .: Nucl. Instr. Andnd) devised a two-dimensional method using a signal processing system consisting of a pulse height discriminating circuit for extracting timing, a fixed time width pulse generation circuit and a coincidence counting circuit. Meth. A430 (1999) 311-320). In this method, the simultaneous counting (coincidence) time set when performing simultaneous counting of signals corresponding to the horizontal and vertical directions in order to ensure a certain level of efficiency for simultaneous detection is a constant that is at least twice the fluorescence lifetime. Time-consuming methods have been used.

  In the present invention, when a two-dimensional radiation image is obtained by performing signal detection using an optical fiber such as a wavelength shift fiber in a two-dimensional radiation image detector using a scintillator or a phosphor, a mounting operation may be required depending on conventional methods. An object of the present invention is to facilitate the production of a two-dimensional radiation image detector in which a large number of small scintillators that have been difficult are arranged on a plane.

  An object of the present invention is to make it possible to apply a phosphor to a two-dimensional radiation image detector using large pixels, which has been difficult to realize in a two-dimensional radiation image detector using a phosphor sheet.

  In addition, when a two-dimensional radiation image detector is configured using a scintillator and a phosphor, even if it is difficult to increase the thickness of the radiation detector and it is difficult to increase the detection efficiency, the two are combined. The purpose is to improve the detection efficiency.

  Furthermore, a two-dimensional radiation using a method of detecting photons using an optical fiber such as a wavelength shift fiber in which a scintillator or a phosphor having a short fluorescence lifetime is used and the generated fluorescence is arranged in a lattice form in the vertical and horizontal directions. The purpose is to increase the counting rate of the image detector.

  Another object of the present invention is to provide a detection apparatus capable of performing not only radiation but also two-dimensional neutron image detection of neutrons at high speed and easily.

  In order to achieve the above object, in the present invention, in the case of a two-dimensional radiation image detector using a scintillator, the pixel size determined in the horizontal and vertical directions of the scintillator plate is based on the scintillator plate having a large area. Fluorescence between the pixels is created by creating grooves at intervals and embedding a fluorescent reflector such as MgO in the grooves, or a material that reflects fluorescence and has a high gamma ray absorption rate, or a material that reflects fluorescence and has a large neutron absorption cross section. The position detection performance for gamma rays or neutrons is improved by preventing leakage and improving the fluorescence radiation efficiency on the fluorescence detection surface and using a material having a large gamma ray or neutron absorption capability. In addition, by arranging an optical fiber such as a wavelength shift fiber in the groove and performing fluorescence readout from the side surface of the pixel, it is possible to detect a multifunctional radiation image.

In the case of a phosphor, a transparent block, a wavelength shifter block, or a scintillator block is used as a fluorescent light collecting substrate, and an optical fiber such as a wavelength shift fiber is disposed on the side surface of the conventional substrate to detect fluorescence. A two-dimensional radiation image detector is used.
By making the radiation detector a structure that can be used in combination with a phosphor and a scintillator, it is possible to improve the detection efficiency even when it is difficult to increase the thickness of the phosphor and it is difficult to increase the detection efficiency. And

On the other hand, by using a detector for neutrons containing, mixed, or combined with one or more types of ⁶ Li, ¹⁰ B, or Gd, which is a neutron converter material that converts neutrons into ionizable radiation in the detection body, two-dimensional Neutron images can be obtained.

  Since the present invention is configured as described above, the following effects can be obtained. A two-dimensional radiation image detector using a scintillator, which has been troublesome and difficult to manufacture due to the arrangement of many scintillator blocks in the past, can be easily manufactured based on a scintillator plate having a large area according to the present invention. Therefore, it is possible to manufacture a two-dimensional radiation image detector having a large area at low cost.

  A radiation image detector or a neutron image detector with improved position detection performance for gamma rays or neutrons can be realized by arranging a material that is a fluorescent reflector and a gamma ray or neutron absorber on the side surface of the detector.

  Using a combination of a phosphor and a transparent block, wavelength shifter block, or scintillator block, a two-dimensional radiation image detector using a large area phosphor with a relatively large area of pixels, which was not possible with the conventional method, is realized. can do.

  Furthermore, by adopting a structure in which a phosphor and a scintillator can be used in combination, a radiation image detector with improved detection efficiency or a multi-function can be realized.

  A two-dimensional neutron image detector can be realized by using a combination of the radiation image detector using a scintillator or a phosphor and a neutron converter material. Since the scintillator and the phosphor are not so thick from the viewpoint of positional resolution, an optimum X-ray image detector or two-dimensional neutron image detector can be produced.

A reference technology for a two-dimensional radiation image detector composed of detection pixels made of a scintillator plate made by embedding and dividing a fluorescent reflector in a groove formed on the upper surface in the horizontal and vertical directions of the scintillator plate It is. A two-dimensional radiation image composed of detection pixel groups made by using a scintillator plate as a raw material and embedding and reflecting fluorescent reflectors in grooves created alternately on the top and bottom surfaces in the horizontal and vertical directions of the scintillator plate This is a reference technology for detectors. A reference technology for a two-dimensional radiation image detector composed of detection pixels made by using a scintillator plate as a raw material and embedding and separating a radiation absorbing material in a groove formed in the horizontal and vertical upper surfaces of the scintillator plate It is. A two-dimensional neutron image consisting of a group of detection pixels made from a scintillator plate containing a neutron converter and embedded with a neutron absorber in a groove made on the top and bottom of the scintillator plate. This is a reference technology for detectors. Fluorescence emitted from the scintillator using a wavelength-shifted fiber bundle placed in a groove made on the top surface in the horizontal and vertical directions of the scintillator plate and a wavelength-shifted fiber bundle placed on the bottom surface of the scintillator plate. This is a reference technique of a two-dimensional radiation image detector that obtains a two-dimensional image of radiation by detecting Using a scintillator plate as a raw material, using a wavelength shift fiber bundle arranged in a groove formed on the horizontal and vertical top surfaces of the scintillator plate and a wavelength shift fiber bundle arranged on the bottom surface of the scintillator plate, arranged on the top surface of the scintillator plate This is a reference technique for a two-dimensional radiation image detector that obtains a two-dimensional image of radiation by detecting fluorescence emitted from a radiation detector and a scintillator. Li glass phosphor Y ₂ SiO disposed on an upper surface of the scintillator _5: an example of the fluorescence due to α rays Ce was detected fluorescence spectrum in its side through the Li glass scintillator (above). For comparison, an example measured on the back surface of a Li glass scintillator is shown below. Using a quartz glass plate, which is a fluorescent concentrator, as a raw material, using a wavelength shift fiber bundle arranged in a groove formed on the upper surface in the vertical direction of the quartz glass plate and an optical fiber bundle arranged on the lower surface of the scintillator plate, This is a reference technique of a two-dimensional radiation image detector that obtains a two-dimensional image of radiation by detecting fluorescence emitted from the. This is an example in which the fluorescence spectrum of the phosphor Y ₂ SiO ₅ : Ce arranged on the upper surface of quartz glass is detected on the side surface through the quartz glass. Using a wavelength shifter plate, which is a fluorescent concentrator, as a material, a wavelength shift fiber bundle disposed in a groove formed on the upper surface in the vertical direction of the wavelength shifter plate and a wavelength shift fiber bundle disposed on the lower surface of the scintillator plate This is a reference technique of a two-dimensional radiation image detector that obtains a two-dimensional image of radiation by detecting fluorescence converted in wavelength by a shifter. This is an example in which the fluorescence spectrum is detected on the side surface of the fluorescent substance Y ₂ SiO ₅ : Ce arranged on the upper surface of the wavelength shifter through the wavelength shifter. Using a scintillator plate as a raw material, grooves are alternately formed on the upper surface and the lower surface in the horizontal and vertical directions of the scintillator plate, and a wavelength shift fiber bundle disposed in the vertical groove and a wavelength shift fiber bundle disposed on the lower surface of the scintillator plate This is a reference technique for a two-dimensional radiation image detector that obtains a two-dimensional image of radiation by detecting fluorescence emitted from the scintillator using the. Fluorescence emitted from the scintillator is detected using a wavelength shift fiber bundle arranged in the horizontal direction on the upper and lower surfaces of rectangular scintillator blocks arranged in a plane and a wavelength shift fiber bundle arranged in the vertical direction on the side surface of the scintillator block. This is an embodiment of a two-dimensional radiation image detector that obtains a two-dimensional image of radiation. Fluorescence emitted from the scintillator is detected using a wavelength-shifted fiber bundle disposed on opposite side surfaces of rectangular scintillator blocks arranged in a plane and a wavelength-shifted fiber bundle disposed laterally on the lower surface of the scintillator block. This is an embodiment of a two-dimensional radiation image detector that obtains a two-dimensional image of radiation. Radiation detection placed on the top surface of the scintillator block using a wavelength-shifted fiber bundle placed on the opposite side surfaces of rectangular scintillator blocks arranged in a plane and a wavelength-shifted fiber bundle placed laterally on the bottom surface of the scintillator block 2 is an example of a two-dimensional radiation image detector that obtains a two-dimensional image of radiation by detecting fluorescence emitted from the body and scintillator. Using a wavelength-shifted fiber bundle arranged on the opposite side surface of the quartz glass block, which is a rectangular fluorescent concentrator arranged in a plane, and a wavelength-shifted fiber bundle arranged laterally on the lower surface of the quartz glass block, quartz is used. This is a reference technique for a two-dimensional radiation image detector that obtains a two-dimensional image of radiation by detecting fluorescence emitted from a radiation detector disposed on the upper surface of a glass block. Wavelength shift fiber bundles arranged on opposite sides in the vertical direction of the wavelength shifter block, which are rectangular fluorescent light collectors arranged in a plane, and wavelength shift fiber bundles arranged in the lateral direction on the lower surface of the wavelength shifter block This is a reference technique for a two-dimensional radiation image detector that obtains a two-dimensional image of radiation by detecting fluorescence emitted from a radiation detector disposed on the upper surface of the shifter block and wavelength-converted by the wavelength shifter block. From the radiation detectors and scintillator blocks arranged on the upper and lower surfaces of the scintillator block, using wavelength-shifted fiber bundles arranged on the opposite side surfaces in the vertical direction and the opposite side surfaces of the rectangular scintillator blocks arranged in a plane This is a reference technique for a two-dimensional radiation image detector that obtains a two-dimensional image of radiation by detecting emitted fluorescence. The wavelength shift fiber bundles are arranged on the opposite sides in the vertical direction and the opposite sides of the quartz glass block, which are rectangular fluorescent light collectors arranged in a plane, and placed on the upper and lower surfaces of the quartz glass block. This is a reference technique for a two-dimensional radiation image detector that obtains a two-dimensional image of radiation by detecting fluorescence emitted from the radiation detector. The wavelength shifter bundles are arranged on the opposite side surfaces in the vertical direction and the opposite side surfaces of the wavelength shifter block, which are rectangular fluorescent light collectors arranged in a plane, and are arranged on the upper and lower surfaces of the wavelength shifter block. This is a reference technique for a two-dimensional radiation image detector that obtains a two-dimensional image of radiation by detecting fluorescence emitted from a radiation detector and wavelength-converted by a wavelength shifter block. This is a reference technology in which every other wavelength-shifting fiber bundle is vertically crossed vertically when placing wavelength-shifting fiber bundles on opposite sides of a rectangular block in the vertical and horizontal directions. is there. A scintillator plate containing a neutron converter is used as a raw material, and a wavelength shift fiber bundle disposed in a groove formed on the upper surface in the vertical direction of the scintillator plate and a wavelength shift fiber bundle disposed on the lower surface of the scintillator plate are used on the upper surface of the scintillator plate. This is an embodiment of a two-dimensional neutron image detector that obtains a two-dimensional image of neutrons by detecting fluorescence emitted from the arranged radiation detector and scintillator. A liquid scintillator partitioned into a lattice using a wavelength shift fiber bundle disposed perpendicularly to the upper and lower portions of a detection container filled with the liquid scintillator, in which reflector blocks partitioned in a lattice are disposed. This is a reference technique of a two-dimensional radiation image detector that obtains a two-dimensional image of radiation by detecting fluorescence emitted from the. An optical fiber detection block in which wavelength-shifted fiber bundles are arranged in a lattice shape so as to be orthogonal to the vertical direction and the horizontal direction is arranged in the height direction of the detection container filled with the liquid scintillator, and is divided into a lattice shape by the optical fiber detection block. This is a reference technique for a two-dimensional radiation image detector that obtains a two-dimensional image of radiation by detecting fluorescence emitted from the liquid scintillator. An optical fiber detection block in which wavelength-shifted fiber bundles are arranged in a lattice shape so as to be orthogonal to the vertical direction and the horizontal direction is arranged in the height direction of the detection container filled with the liquid scintillator, and is divided into a lattice shape by the optical fiber detection block. by detecting the fluorescence emitted from the radiation detector and a liquid scintillator disposed on the upper and lower surfaces of the detection vessel is a two-dimensional radiation image detector of the reference technique for obtaining a 2-dimensional image of radiation. It is an example of the two-dimensional radiation image detector of the structure which added the liquid scintillator circulation mechanism comprised from a valve, piping, and a pump to the detection container filled with the liquid scintillator. An optical fiber detection block having a wavelength shift fiber bundle in a lattice shape perpendicular to the vertical direction and the horizontal direction is arranged in the height direction of a detection container filled with a liquid scintillator including a neutron converter, and the optical fiber detection block This is a reference technique for a two-dimensional neutron image detector that obtains a two-dimensional image of neutrons by detecting fluorescence emitted from a neutron detector and a liquid scintillator placed on the upper and lower surfaces of a detection vessel partitioned in a grid by is there. Fluorescence detection of a two-dimensional radiation image detector composed of detection pixels made by using a scintillator plate as a raw material and embedding and dividing a fluorescent reflector in grooves formed on the horizontal and vertical upper surfaces of the scintillator plate It is the Example which used the streak camera as a detector for an object. Comparison of a method for generating a constant time width pulse using a conventional pulse generator and a method for generating a pulse signal with a time width determined based on Poisson distribution using the retriggerable retriggerable pulse signal generator of the present invention FIG. A scintillator plate containing a neutron converter is used as a raw material, and a wavelength shift fiber bundle disposed in a groove formed on the upper surface in the vertical direction of the scintillator plate and a wavelength shift fiber bundle disposed on the lower surface of the scintillator plate are used on the upper surface of the scintillator plate. Recorded as a time-series signal using a parallel signal input circuit and a signal recording / analysis device, and analyzed based on the simultaneous measurement method, a pulse signal created based on the emitted neutron detector and fluorescence emitted from the scintillator, This is a reference technique for a two-dimensional neutron image detector that obtains a two-dimensional image of neutrons. A two-dimensional radiation image for obtaining a two-dimensional image of radiation by detecting fluorescence emitted from the scintillator block using a wavelength-shifted fiber bundle arranged so as to be orthogonal to the vertical direction of the upper surface of the scintillator block and the horizontal direction of the lower surface of the scintillator block It is an example of the conventional method of a detector. Two-dimensional radiation that obtains a two-dimensional image of radiation by detecting fluorescence emitted from the scintillator block using a wavelength-shifted fiber bundle arranged so as to be orthogonal to the opposite side surfaces of the scintillator block in the vertical and horizontal directions It is an example of the conventional method of an image detector.

  In a two-dimensional radiation image detector using a scintillator, it is easy to create a groove based on a scintillator plate with a large area, which was troublesome to manufacture because a large number of scintillator blocks are arranged in the conventional method. Can be made. By using a method of arranging a gamma ray or a neutron absorber on the side as well as a fluorescent reflector, it is possible to increase the fluorescence radiation efficiency on the fluorescence detection surface and at the same time improve the position detection performance for gamma rays or neutrons. Also, multifunctional radiation image detection can be performed by performing fluorescence readout from the side surface of the pixel.

  In a two-dimensional radiation image detector using a phosphor, a transparent substrate, a wavelength shifter substrate, a scintillator plate, or the like is used as a fluorescence readout substrate, so that a large area having pixels of a relatively large area that cannot be achieved by the conventional method. A two-dimensional radiation image detector may be possible.

  Further, by adopting a structure in which a phosphor and a scintillator can be used in combination, detection efficiency is improved or multifunctional radiation image detection is possible. On the other hand, when a radiation image is constructed based on the lateral photon detection signal and the longitudinal photon detection signal, a retriggerable that generates a pulse in a retriggerable state based on the timing pulse signal output from the pulse height discriminator. A pulse signal generator is used to generate a pulse signal whose time width is determined based on the Poisson distribution corresponding to the fluorescence lifetime of the detection medium, and this signal is used to generate a two-dimensional radiation image based on the simultaneous measurement method. Ask for. Since the pulse time width used for simultaneous measurement can be shortened rather than using a pulse generator that generates a constant time width according to the conventional method, a high counting rate can be achieved.

  A two-dimensional neutron image can be obtained by using a combination of a scintillator or phosphor and a neutron converter material.

( Reference technology 1)
As a reference technique 1, a two-dimensional radiation image detector according to the present invention will be described with reference to FIG. In the present invention, a groove having a depth more than half the thickness of the scintillator plate is formed on the upper surface of the scintillator plate that generates fluorescence when radiation is incident, at intervals determined in the horizontal direction and the vertical direction. By embedding a reflective material to reflect, a detection pixel group is formed by dividing the horizontal and vertical grooves, and the two-dimensional image of the radiation is detected by detecting the fluorescence of the radiation incident on the detection pixel. It is characterized by obtaining.

As a scintillator plate used as a material for a two-dimensional radiation image detector, a plastic scintillator BC-412 manufactured by Bicron, USA, which has been conventionally used as a detection medium for ionizing radiation such as X-rays or α rays, can be used. . The fluorescence lifetime is 3.3 ns, and the fluorescence wavelength is 434 nm. And as an example, the size of the scintillator plate width 100mm, the vertical width 100mm and thickness 2 mm. Using a diamond cutter or the like, grooves having a width of 0.5 mm and a depth of 1.5 mm are formed in the scintillator plate at intervals of 2 mm in the horizontal direction and at intervals of 2 mm in the vertical direction. By burying Al ₂ O ₃ or MgO, which is a fluorescent reflecting material conventionally used, in this groove, a detection pixel group divided into horizontal and vertical grooves is formed. By forming a depth more than half of the thickness of the scintillator plate, there is almost no degradation in position resolution due to fluorescence leakage between detection pixels.

  The two-dimensional radiation image detector of the present invention is a conventional method in which fluorescence of radiation incident on a detection pixel is irradiated with a horizontal optical fiber bundle on the upper surface of the two-dimensional radiation image detector and a vertical optical fiber on the lower surface. A two-dimensional radiation image detector can be constructed by arranging in a lattice in a bundle and applying the coincidence counting method. As the optical fiber bundle, for example, a wavelength shift fiber BCF-92 manufactured by Bikinron in the United States that matches the fluorescence wavelength of the plastic scintillator BC-412 can be used. In order to increase the fluorescence detection efficiency using the wavelength shift fiber, a fluorescent reflector is disposed on the end face of the wavelength shift fiber that is not connected to the photodetector. This method can improve detection efficiency by several tens of percent or more. In FIG. 1, the wavelength shift fibers are arranged as a bundle for each pixel, but there is no problem even if they are arranged continuously. In this case, it is also possible to adopt a method in which the wavelength shift fiber between the detection pixels is thinned out and not connected to the photodetector. Also. A method of placing a fluorescent reflector on the back surface of the wavelength shift fiber can also be used as a method for slightly increasing the fluorescence detection with the wavelength shift fiber.

As a scintillator plate used as a material for the two-dimensional radiation image detector, a glass scintillator, a CsI scintillator, a YAlO ₃ : Ce scintillator, a GSO scintillator, or the like can be used. Further, as the optical fiber bundle, a side incident type optical fiber configured such that a part of the side surface of the optical fiber is scraped and light can be input from the side surface can be used.

( Reference technology 2)
As Reference Technique 2, a two-dimensional radiation image detector according to the present invention will be described with reference to FIG. According to the present invention, the thickness of the scintillator plate is determined at predetermined intervals on the upper surface and the lower surface of the scintillator plate that generates fluorescence when radiation is incident, alternately on the upper surface and the lower surface in the horizontal direction, and alternately on the upper surface and the lower surface in the vertical direction. By forming a groove with a depth of more than half and embedding a reflective material that reflects fluorescence in this groove, a detection pixel group is formed by dividing the groove in the horizontal and vertical directions, and enters the detection pixel. It is characterized by obtaining a two-dimensional image of radiation by detecting fluorescence of the emitted radiation.

As this reference technique , a plastic scintillator BC-412 which is the same two-dimensional radiation image detector as in Reference technique 1 can be used, and the size of the scintillator plate is 100 mm in width, 100 mm in length, and 2 mm in thickness. Using a diamond cutter, etc., a groove having a width of 0.5 mm and a depth of 1.5 mm on the upper and lower surfaces of the scintillator plate at intervals of 2 mm alternately between the upper surface and the lower surface in the horizontal direction and at intervals of 2 mm alternately between the upper surface and the lower surface in the vertical direction. make. By burying Al ₂ O ₃ or MgO, which is a conventionally used fluorescent reflecting material, in this groove, a detection pixel group divided into horizontal and vertical grooves formed alternately on the upper surface and the lower surface is formed. Constitute. The two-dimensional radiation image detector of the present invention can be configured as a two-dimensional radiation image detector by the same conventional method as in Reference Technique 1.

( Reference technology 3)
As reference technique 3, a two-dimensional neutron image detector according to the present invention will be described with reference to FIG. In the present invention, a two-dimensional radiation image detector is produced by the same method as the above-described Reference Technique 1 or 2, and a function of shielding radiation between detection pixels is added by using a material having a large radiation shielding effect as a reflecting material. It is characterized by obtaining a dimensional image.

  By embedding silver powder or the like, which is an element of element number 40 or more and white and also serves as a fluorescent reflecting material, in the groove of the two-dimensional radiation image detector, radiation is shielded between the detection pixels to provide a collimating function, and position detection performance is improved. Improvements can be made.

( Reference technology 4)
As Reference Technique 4, a two-dimensional neutron image detector according to the present invention will be described with reference to FIG. In the present invention, a material containing at least ⁶ Li, ¹⁰ B, or Gd, which is a neutron converter, is used as a scintillator plate, and a two-dimensional radiation image detector is formed on the scintillator plate by the same method as in Reference Technique 1 or 2 above. It is characterized by using a material with a large neutron shielding effect as a reflector and adding a function of shielding neutrons between detection pixels to obtain a two-dimensional image of neutrons.

In this reference technology , a ⁶ Li glass scintillator (GS20 manufactured by Bikeron) containing 6.6% of ⁶ Li, which is a neutron converter, is used as the scintillator plate. The fluorescence lifetime is 60 ns, and the fluorescence wavelength is 390 nm. By embedding Gd ₂ O ₃ , which is a material containing an element having a large neutron absorption cross-sectional area as a reflective material, and also white as a fluorescent reflective material in the groove of this two-dimensional radiation image detector, neutron shielding is provided between detection pixels. The position detection performance can be improved by providing a collimating function.

( Reference technology 5)
As reference technique 5, a two-dimensional radiation image detector according to the present invention will be described with reference to FIG. In the present invention, a groove having a depth of more than half the thickness of the scintillator plate is formed on the upper surface of the scintillator plate that generates fluorescence when radiation is incident, at intervals determined in the horizontal direction and the vertical direction. An optical fiber bundle is disposed, and a reflecting material that reflects fluorescence is embedded in a lateral groove, and light is transmitted in a lateral direction that is a direction perpendicular to the optical fiber on the upper surface or lower surface of the scintillator plate or on the upper and lower surfaces. A fiber bundle is arranged, and the fluorescence of the radiation incident on the detection pixel formed by dividing the horizontal and vertical grooves into the optical fiber bundle arranged in the groove of the scintillator plate and the upper surface or the lower surface or the upper and lower surfaces. It is characterized by obtaining a two-dimensional image of radiation by detecting with the arranged optical fiber bundle.

As a scintillator plate used as a material for the two-dimensional radiation image detector, a plastic scintillator BC-412 manufactured by Bikeron, Inc., USA can be used. The fluorescence lifetime is 3.3 ns, and the fluorescence wavelength is 434 nm. As an example , the scintillator plate has a width of 200 mm, a vertical width of 200 mm, and a thickness of 2 mm. Using a diamond cutter or the like, grooves having a width of 0.6 mm and a depth of 1.5 mm are formed in the scintillator plate at intervals of 5 mm in the horizontal direction and at intervals of 5 mm in the vertical direction. Three optical fibers having a thickness of 0.5 mm are arranged in the horizontal groove, and Al ₂ O ₃ which is a fluorescent reflecting material conventionally used as a reflecting material for reflecting fluorescence is arranged in the vertical groove. Embed MgO or the like. A detection pixel is configured which is divided into a horizontal groove and a vertical groove. By detecting the fluorescence of the radiation incident in the detection pixel by the optical fiber bundle disposed in the groove and the optical fiber bundle having 10 optical fibers having a thickness of 0.5 mm on the upper surface, two-dimensional radiation is detected. An image can be obtained. As the optical fiber, BCF-92, which is a wavelength shift fiber, can be used.

( Reference technology 6)
As a reference technique 6, a two-dimensional radiation image detector according to the present invention will be described with reference to FIG. In the present invention, a groove having a depth of more than half the thickness of the scintillator plate is formed on the upper surface of the scintillator plate that generates fluorescence when radiation is incident, at intervals determined in the horizontal direction and the vertical direction. An optical fiber bundle is arranged, a reflecting material that reflects fluorescence is embedded in a lateral groove, an optical fiber bundle is arranged in the lateral direction perpendicular to the optical fiber on the lower surface of the scintillator plate, and the upper surface A radiation detector that emits fluorescence by radiation is placed on the detector, and the fluorescence generated from the radiation detector is separated by a groove in the horizontal and vertical directions. It is characterized by obtaining a two-dimensional image of radiation by detecting the fluorescence generated from the light with an optical fiber bundle arranged in the groove of the scintillator plate and an optical fiber bundle arranged on the lower surface. That.

In this reference technique , a Li glass scintillator is used as a scintillator plate used as a material for a two-dimensional radiation image detector. The fluorescence lifetime is 60 ns, and the fluorescence wavelength is 390 nm. As an example , the scintillator plate has a width of 200 mm, a vertical width of 200 mm, and a thickness of 2 mm. Using a diamond cutter or the like, grooves having a width of 0.6 mm and a depth of 1.5 mm are formed in the scintillator plate at intervals of 5 mm in the horizontal direction and at intervals of 5 mm in the vertical direction. Three optical fibers having a thickness of 0.5 mm are arranged in the horizontal groove, and Al ₂ O ₃ which is a fluorescent reflecting material conventionally used as a reflecting material for reflecting fluorescence is arranged in the vertical groove. Embed MgO or the like. A detection pixel is configured which is divided into a horizontal groove and a vertical groove.

As the detector, a phosphor Y ₂ SiO ₅ : Ce having a fluorescence wavelength close to 390 nm which is the fluorescence wavelength of Li glass scintillator can be used. The fluorescence lifetime is 40 ns and the fluorescence wavelength is 410 nm. When a 2 mm thick Li glass scintillator with a size of ₅ mm × ₅ mm is coated with Y ₂ SiO ₅ : Ce powder and irradiated with about 5 MeV alpha rays using a ²⁴¹ Am alpha ray source, the Li glass scintillator FIG. 7 shows the fluorescence spectrum of the fluorescence emitted to the side surface. The intensity of the fluorescence detected on the side of the scintillator is not much different from the intensity detected on the back of the scintillator. As a result, it has been confirmed that the fluorescence of Y ₂ SiO ₅ : Ce can be detected on the side surface via the Li glass scintillator.

  Therefore, the fluorescence of the radiation incident on the detection pixel and the radiation incident on the radiation detector by the optical fiber bundle arranged in the groove and the optical fiber bundle having 10 optical fibers having a thickness of 0.5 mm on the upper surface. By detecting the fluorescence, it is possible to efficiently obtain a two-dimensional image of radiation. As the optical fiber, BCF-92 manufactured by Bikinron, Inc., which is a wavelength shift fiber sensitive to a wavelength of 410 nm, or the like can be used.

In this reference technique , a powdered phosphor is used as a detection medium, but a thin scintillator or the like can be used. In FIG. 6, the radiation detector is arranged for each detection pixel. However, the same result can be obtained by arranging the sheet-like radiation detector over the entire upper part of the scintillator plate. It is more effective to increase the adhesion by using optical grease or the like at the time of placement.

( Reference technology 7)
As reference technique 7, a two-dimensional radiation image detector according to the present invention will be described with reference to FIG. In the present invention, a groove having a depth more than half of the thickness of the scintillator plate is formed on the upper surface of the fluorescent light collector having a transmittance sufficiently transmitting the fluorescent wavelength at intervals determined in the horizontal direction and the vertical direction. The optical fiber bundle is disposed in the groove of the light source, and the reflecting groove for reflecting the fluorescence is embedded in the groove in the horizontal direction, and light is transmitted in the lateral direction that is perpendicular to the optical fiber bundle on the lower surface of the fluorescent light collecting plate. Radiation that enters a detection pixel created by placing a fiber bundle, placing a radiation detector that generates fluorescence by radiation on the upper surface, and separating the fluorescence generated from the radiation detector by grooves in the horizontal and vertical directions A feature of the present invention is that a two-dimensional image of radiation is obtained by detecting fluorescence generated from a detector with an optical fiber bundle disposed in a groove of a fluorescent light collector and an optical fiber bundle disposed on a lower surface.

The present invention is used when a phosphor, particularly a phosphor on powder is used as a detection medium of a two-dimensional radiation image detector. For example, BaFBr: Eu ²⁺ , Y ₂ SiO ₅ : Ce, YAlO ₃ : Ce, ZnS: Ag, etc. used for detecting X-rays, β-rays or α-rays can be used as the phosphor. In one example , Y ₂ SiO ₅ : Ce is used as the phosphor. The fluorescence lifetime is 40 ns and the fluorescence wavelength is 410 nm. Quartz glass is used as the fluorescent light collector having a transmittance that allows the fluorescent wavelength to pass sufficiently. Quartz glass has sufficient transmission performance for wavelengths of 300 nm or more. As an example , the size of the fluorescent light collector is 200 mm in width, 200 mm in length, and 2 mm in thickness. Using a diamond cutter or the like, grooves having a width of 0.6 mm and a depth of 1.5 mm are formed in the scintillator plate at intervals of 5 mm in the horizontal direction and at intervals of 5 mm in the vertical direction. Three optical fibers having a thickness of 0.5 mm are arranged in the horizontal groove, and Al ₂ O ₃ which is a fluorescent reflecting material conventionally used as a reflecting material for reflecting fluorescence is arranged in the vertical groove. Embed MgO or the like. As a result, it is possible to form a detection pixel using Y ₂ SiO ₅ : Ce divided into grooves in the horizontal and vertical directions as a radiation detection medium.

When Y ₂ SiO ₅ : Ce powder is applied to the upper surface of quartz glass, which is a fluorescent light collector having a size of 5 mm × 5 mm and a thickness of 2 mm, and the radiation detector is irradiated with about 5 MeV alpha rays using a ²⁴¹ Am alpha ray source. FIG. 9 shows the fluorescence spectrum of the fluorescence emitted on the side surface of the quartz glass. As a result, it was found that the fluorescence generated from Y ₂ SiO ₅ : Ce can be detected on the side surface through quartz glass.

  Therefore, by detecting the fluorescence of the radiation incident in the detection pixel by the optical fiber bundle arranged in the groove and the optical fiber bundle having 10 optical fibers having a thickness of 0.5 mm on the upper surface, the radiation of the radiation is detected. A two-dimensional image can be obtained. As the optical fiber, BCF-92 manufactured by Bicron, USA, which is a wavelength shift fiber sensitive to 410 nm, or the like can be used.

In this reference technique , a powdered phosphor is used as a detection medium, but a thin scintillator or the like can be used.

( Reference technology 8)
As a reference technique 8, a two-dimensional radiation image detector according to the present invention will be described with reference to FIG. The present invention, on the upper surface of the wavelength shifter plate having a function of shifting the fluorescence wavelength to another wavelength, a groove having a depth of more than half of the thickness of the scintillator plate at intervals determined in the horizontal direction and the vertical direction, An optical fiber bundle is arranged in the vertical groove, and a reflecting material that reflects fluorescence is embedded in the horizontal groove, and the lower side of the wavelength shifter plate is in a direction perpendicular to the optical fiber. An optical fiber bundle is placed, a radiation detector that generates fluorescence by radiation is placed on the top surface, and the fluorescence generated from the radiation detector is converted to another wavelength by the wavelength shift function of the wavelength shifter plate. It is characterized by obtaining a two-dimensional image of radiation by detecting with an optical fiber bundle arranged in the groove of the wavelength shifter plate and an optical fiber bundle arranged on the upper surface or the lower surface. The present invention is used when a phosphor, particularly a phosphor on powder is used as a detection medium of a two-dimensional radiation image detector. For example, BaFBr: Eu ²⁺ , Y ₂ SiO ₅ : Ce, YAlO ₃ : Ce, ZnS: Ag, etc. used for detecting X-rays, β-rays or α-rays can be used as the phosphor. Further, as a wavelength shifter plate having a function of shifting the fluorescence wavelength to another wavelength, a plastic wavelength shifter or the like can be used. In this reference technique , Y ₂ SiO ₅ : Ce is used as the phosphor. The fluorescence lifetime is 40 ns and the fluorescence wavelength is 410 nm. In addition, as a wavelength shifter plate, a plastic wavelength shifter BC-484 manufactured by Bikeron, USA is used. As an example , the size of the wavelength shifter plate is set to be 200 mm in width, 200 mm in length, and 2 mm in thickness. Using a diamond cutter or the like, grooves having a width of 0.6 mm and a depth of 1.5 mm are formed in the wavelength shifter plate at intervals of 5 mm in the horizontal direction and at intervals of 5 mm in the vertical direction. Three optical fibers having a thickness of 0.5 mm are arranged in the horizontal groove, and Al ₂ O ₃ which is a fluorescent reflecting material conventionally used as a reflecting material for reflecting fluorescence is arranged in the vertical groove. Embed MgO or the like. As a result, it is possible to form a detection pixel using Y ₂ SiO ₅ : Ce divided into grooves in the horizontal and vertical directions as a radiation detection medium.

When a 2 mm thick 5 mm × ₅ mm wavelength shifter plate is coated with Y ₂ SiO ₅ : Ce powder and a radiation detector is irradiated with about 5 MeV alpha rays using a ²⁴¹ Am alpha ray source, the wavelength shifter plate FIG. 11 shows the fluorescence spectrum of the wavelength-shifted fluorescence emitted to the side surface. It can be seen that the fluorescence having the central wavelength of 410 nm is converted to the fluorescence of 434 nm. As a result, it was found that the fluorescence generated from Y ₂ SiO ₅ : Ce can be detected on the side surface through the wavelength shifter plate.

  Therefore, by detecting the fluorescence of the radiation incident in the detection pixel by the optical fiber bundle arranged in the groove and the optical fiber bundle having 10 optical fibers having a thickness of 0.5 mm on the upper surface, the radiation of the radiation is detected. A two-dimensional image can be obtained. As the optical fiber, Y-7 or Y-11 manufactured by Kuraray Co., Ltd., which is a wavelength shift fiber sensitive to 434 nm, can be used.

In this reference technique , a powdered phosphor is used as a detection medium, but a thin scintillator or the like can be used.

( Reference technology 9)
As Reference Technique 9, a two-dimensional radiation image detector according to the present invention will be described with reference to FIG. The present invention relates to the above-described Reference Technique 6-8, in which the upper surface and the lower surface of the scintillator plate, the fluorescent light collector plate, or the wavelength shifter plate are alternately spaced apart by the upper surface and the lower surface in the horizontal direction and the upper surface and the lower surface in the vertical direction. By forming a groove with a depth of more than half the thickness of the scintillator plate and embedding a reflective material that reflects fluorescence in this groove, a detection pixel group made by dividing the horizontal and vertical grooves is configured. It is characterized by obtaining a two-dimensional image of radiation.

In this reference technique , the wavelength shifter pixel configuration method based on the reference technique 8 is applied to the upper and lower surfaces of the wavelength shifter plate alternately in the horizontal direction and alternately in the vertical direction at predetermined intervals. A detection pixel group created by dividing the horizontal and vertical grooves into a groove with a depth of more than half the thickness of the scintillator plate and embedding a reflective material that reflects fluorescence in this groove. Constitute. The wavelength shifter plate, the radiation detector, the wavelength shift fiber, and the like can use the same materials and configurations as those of the above-described Reference Technique 8.

( Example 1 )
As Example 1 , a two-dimensional radiation image detector according to the present invention will be described with reference to FIG. In the present invention, rectangular scintillator blocks are arranged in a plane in the horizontal direction and the vertical direction, optical fiber bundles are arranged on the opposite side surfaces of each rectangular scintillator block in the vertical direction, and a reflecting material is arranged on the opposite side surfaces in the horizontal direction. And a structure in which a reflector is arranged on the upper surface of the scintillator block, and an optical fiber bundle is arranged in a lateral direction that is perpendicular to the optical fiber bundle arranged on the side surface on the lower surface of the scintillator block arranged in a plane, It is characterized in that a two-dimensional image of radiation is obtained by detecting fluorescence of radiation incident on each rectangular scintillator block with an optical fiber bundle disposed on the side surface of the scintillator block and an optical fiber bundle disposed on the lower surface.

In this embodiment, a Li glass scintillator is used as a rectangular scintillator used as a material for the two-dimensional radiation image detector. The fluorescence lifetime is 60 ns, and the fluorescence wavelength is 390 nm. As one example, the size of one scintillator block is a square having a width of 5 mm, a width of 5 mm, and a thickness of 2 mm. Ten scintillator blocks are arranged on a plane in the horizontal direction and ten in the vertical direction. Four optical fibers having a thickness of 0.5 mm are arranged on opposite side surfaces of the scintillator block in the vertical direction, and the side surfaces in the horizontal direction are fluorescent reflection materials conventionally used as a reflection material for reflecting fluorescence. Al ₂ O ₃ or MgO is disposed. Further, a fluorescent reflecting material is also disposed on the upper surface of the scintillator block. One scintillator block constitutes a detection pixel. 10 optical fibers having a thickness of 0.5 mm are arranged in the lateral direction on the lower surface of the scintillator block, and the radiation incident on the detection pixel using this optical fiber bundle and the optical fiber bundle arranged in the lateral direction on the side surface of the scintillator block. By detecting this fluorescence, a two-dimensional image of radiation can be obtained. In addition, as an optical fiber, BCF-92 manufactured by USA Bicron, which is a wavelength shift fiber that is sensitive to a wavelength of 390 nm, can be used.

( Example 2 )
As a second embodiment, a two-dimensional radiation image detector according to the present invention will be described with reference to FIG. In the present invention, rectangular scintillator blocks are arranged in a plane in the horizontal direction and the vertical direction, optical fiber bundles are arranged on the opposite side surfaces of each rectangular scintillator block in the vertical direction, and a reflecting material is arranged on the opposite side surfaces in the horizontal direction. The optical fiber bundles are arranged in the lateral direction, which is perpendicular to the optical fiber bundles arranged on the side surfaces on the upper and lower surfaces of the scintillator blocks arranged and arranged in a plane, and the radiation incident on each rectangular scintillator block It is characterized in that a two-dimensional image of radiation is obtained by detecting fluorescence with an optical fiber bundle disposed on the side surface of the scintillator block and an optical fiber bundle disposed on the upper surface and the lower surface. This embodiment can be realized by arranging ten optical fibers having a thickness of 0.5 mm in the lateral direction on the upper surface of the scintillator block instead of the reflecting material arranged on the upper surface of the scintillator block in the first embodiment . The optical fiber bundle and 10 optical fibers having a thickness of 0.5 mm arranged in the horizontal direction on the lower surface of the scintillator block are combined to form a vertical optical fiber bundle, and the optical fiber bundle arranged in the horizontal direction on the side surface of the scintillator block. A two-dimensional image of the radiation can be obtained by detecting the fluorescence of the radiation incident on the detection pixel.

( Example 3 )
As a third embodiment, a two-dimensional radiation image detector according to the present invention will be described with reference to FIG. In the present invention, rectangular scintillator blocks are arranged in a plane in the horizontal direction and the vertical direction, optical fiber bundles are arranged on the opposite side surfaces of each rectangular scintillator block in the vertical direction, and a reflecting material is arranged on the opposite side surfaces in the horizontal direction. A radiation detector that generates fluorescence by radiation is disposed on the upper surface of the scintillator block, and the optical fiber bundle is disposed in a direction perpendicular to the optical fiber bundle disposed on the side surface on the lower surface of the scintillator block arranged in a plane. By detecting the fluorescence of the radiation incident on each rectangular scintillator block and the fluorescence generated from the radiation detector with the optical fiber bundle disposed on the side surface of the scintillator block and the optical fiber bundle disposed on the lower surface, It is characterized by obtaining a two-dimensional image.

In this embodiment, a Li glass scintillator is used as a rectangular scintillator block used as a material for a two-dimensional radiation image detector. The fluorescence lifetime is 60 ns, and the fluorescence wavelength is 390 nm. As one example, the size of one scintillator block is a square having a width of 5 mm, a width of 5 mm, and a thickness of 2 mm. Ten scintillator blocks are arranged on a plane in the horizontal direction and ten in the vertical direction. Four optical fibers having a thickness of 0.5 mm are arranged on opposite side surfaces of the scintillator block in the vertical direction, and the side surfaces in the horizontal direction are fluorescent reflection materials conventionally used as a reflection material for reflecting fluorescence. Al ₂ O ₃ or MgO is disposed. In addition, a radiation detector that generates fluorescence by radiation is disposed on the upper surface of the scintillator block. For example, the radiation detector is a phosphor used for detecting X-rays, β-rays or α-rays, and has a fluorescence wavelength close to the fluorescence wavelength of Li glass scintillator: BaFBr: Eu ²⁺ , Y ₂ SiO ₅ : A powder such as Ce, YAlO ₃ : Ce can be used. One scintillator block having such a structure constitutes a detection pixel. Four optical fibers having a thickness of 0.5 mm are arranged on the lower surface of the scintillator block, and the radiation incident on the detection pixel using this optical fiber bundle and the optical fiber bundle arranged laterally on the side surface of the scintillator block. By detecting this fluorescence, a two-dimensional image of radiation can be obtained. In addition, as an optical fiber, BCF-92 manufactured by USA Bicron, which is a wavelength shift fiber that is sensitive to a wavelength of 390 nm, can be used.

( Reference Technology 10 )
As a reference technique 10 , a two-dimensional radiation image detector according to the present invention will be described with reference to FIG. In the present invention, rectangular fluorescent light collecting blocks having a transmittance sufficient to transmit the fluorescence wavelength are arranged in a plane in the horizontal direction and the vertical direction, and optical fiber bundles are arranged on opposite side surfaces of the respective rectangular fluorescent light collecting blocks in the vertical direction. Are disposed on opposite side surfaces in the lateral direction, and a radiation detector that generates fluorescence by radiation is disposed on the upper surface of the fluorescent light collecting block, and on the lower surface of the fluorescent light collecting block arranged in a plane. A structure in which optical fiber bundles are arranged in a lateral direction that is orthogonal to the optical fiber bundle arranged on the side surface, and the fluorescence generated from the radiation detector arranged in each rectangular fluorescent light collecting block is placed on the side surface of the fluorescent light collecting block. It is characterized by obtaining a two-dimensional image of radiation by detecting with the optical fiber bundle arranged and the optical fiber bundle arranged on the lower surface.

In this reference technique , quartz glass is used as a rectangular fluorescent light collecting block used as a fluorescent light collecting material of a two-dimensional radiation image detector. Quartz glass has sufficient transmission performance for wavelengths of 300 nm or more. As an example , the size of one fluorescent light collecting block is a square having a width of 5 mm, a width of 5 mm, and a thickness of 2 mm. Ten fluorescent light collecting blocks are arranged on a plane in the horizontal direction and ten in the vertical direction. Four optical fibers with a thickness of 0.5 mm are arranged on the opposite side surfaces of the scintillator and Al is a fluorescent reflecting material conventionally used as a reflecting material for reflecting fluorescence on the side surface in the horizontal direction. ₂ O ₃ or MgO is arranged. And the radiation detection body which generate | occur | produces fluorescence with a radiation is arrange | positioned on the upper surface of a fluorescence condensing block. For example, as a radiation detector, a powder such as BaFBr: Eu ²⁺ , Y ₂ SiO ₅ : Ce, YAlO ₃ : Ce, ZnS: Ag, which is a phosphor used for detecting X-rays, β-rays or α-rays. Can be used. A detection pixel is constituted by one scintillator having such a structure. Ten optical fibers having a thickness of 0.5 mm are arranged on the lower surface of the fluorescent light collecting block in the horizontal direction, and this optical fiber bundle and the optical fiber bundle arranged in the horizontal direction on the side surface of the scintillator are used to enter the detection pixel. By detecting the fluorescence of the radiation, a two-dimensional image of the radiation can be obtained. Incidentally, as the optical fiber, BCF-92 manufactured by USA Bicron or Y-11 manufactured by Kuraray Co., Ltd., which is a wavelength shift fiber sensitive to wavelengths from 390 nm to 450 nm, can be used according to the fluorescence wavelength.

( Reference technology 11 )
As a reference technique 11 , a two-dimensional radiation image detector according to the present invention will be described with reference to FIG. According to the present invention, rectangular wavelength shifter blocks having a function of shifting the fluorescence wavelength to another wavelength are arranged in a plane in the horizontal direction and the vertical direction, respectively, and optical fiber bundles are arranged on opposite side surfaces of each rectangular wavelength shifter block in the vertical direction. And a reflector on the opposite side surfaces in the horizontal direction, and a radiation detector that generates fluorescence by radiation on the upper surface of the wavelength shifter block, and on the lower surface of the wavelength shifter block arranged in a plane on the side surface A structure in which optical fiber bundles are arranged in a direction perpendicular to the arranged optical fiber bundles, and fluorescence generated from the radiation detectors arranged in each rectangular wavelength shifter block is converted to other wavelengths by the wavelength shift function of the wavelength shifter block The wavelength-converted fluorescence is detected by the optical fiber bundle arranged on the side surface of the wavelength shifter block and the optical fiber bundle arranged on the bottom surface. By, which features a to obtain a 2-dimensional image of radiation.

In this reference technology , a plastic wavelength shifter BC-484 manufactured by Bikinron, USA, which is a plastic wavelength shifter, is used as a rectangular wavelength shifter block used as a fluorescent light condensing material of a two-dimensional radiation image detector. This plastic wavelength shifter can efficiently convert the wavelength to 434 nm fluorescence sufficiently with respect to the wavelength of 370 nm. As an example , the size of one wavelength shifter block is a square having a width of 5 mm, a width of 5 mm, and a thickness of 2 mm. Ten wavelength shifter blocks are arranged on a plane in the horizontal direction and ten in the vertical direction. Four optical fibers with a thickness of 0.5 mm are arranged on the opposite side surfaces of the wavelength shifter block in the vertical direction, and the side surfaces in the horizontal direction are fluorescent reflection materials conventionally used as a reflection material for reflecting fluorescence. Some Al ₂ O ₃ or MgO is arranged. And the radiation detector which generate | occur | produces fluorescence with a radiation is arrange | positioned on the upper surface of a wavelength shifter block. At this time, in order to shift the wavelength efficiently, a phosphor having a fluorescence wavelength of 370 nm to 400 nm can be used. For example, a powder such as YAlO ₃ : Ce, which is a phosphor used for detecting X-rays, β-rays, or α-rays, can be used as the radiation detector. This phosphor has a fluorescence lifetime of 30 ns and a fluorescence wavelength of 370 nm. The detection pixel is constituted by one plastic wavelength shifter having such a structure. Ten optical fibers having a thickness of 0.5 mm are arranged in the lateral direction on the lower surface of the wavelength shifter block, and the optical fiber bundle and the optical fiber bundle arranged in the lateral direction on the side surface of the scintillator are used to enter the detection pixel. By detecting the fluorescence of the radiation, a two-dimensional image of the radiation can be obtained. As the optical fiber, Y-7 or Y-11 manufactured by Kuraray Co., Ltd., which is a wavelength shift fiber sensitive to 434 nm, can be used.

( Reference technology 12 )
As a reference technique 12 , a two-dimensional radiation image detector according to the present invention will be described with reference to FIG. In the present invention, rectangular scintillator blocks are arranged in a plane in the horizontal direction and in the vertical direction, optical fiber bundles are mounted on opposite side surfaces of the rectangular scintillator blocks in the vertical direction, and the rectangular scintillator blocks in the horizontal direction are mounted. The optical fiber bundles are arranged on the opposite side surfaces, and the scintillator block has an upper surface or a lower surface, or a radiation detector that generates fluorescence by radiation on the upper and lower surfaces, and the radiation fluorescence incident on each rectangular scintillator block. Fluorescence generated from the radiation detectors disposed on the upper surface or the lower surface or on the upper and lower surfaces is detected by the optical fiber bundles disposed on the longitudinal side surface and the lateral side surface of the scintillator block to obtain a two-dimensional image of radiation. It is a feature.

In this reference technique , a Li glass scintillator is used as a rectangular scintillator used as a material for a two-dimensional radiation image detector. The fluorescence lifetime is 60 ns, and the fluorescence wavelength is 390 nm. As an example , the size of one scintillator block is a square having a width of 5 mm, a length of 5 mm, and a thickness of 2 mm. Ten scintillator blocks are arranged on a plane in the horizontal direction and ten in the vertical direction. Two optical fibers having a thickness of 0.5 mm are arranged on the side surfaces facing the scintillator block in the horizontal direction, and two optical fibers having a thickness of 0.5 mm are arranged on the side surfaces facing the vertical direction. On the upper surface of the scintillator block, Al ₂ O ₃ or MgO, which is a fluorescent reflecting material conventionally used as a reflecting material for reflecting fluorescence, is disposed on the lower surface of the scintillator block. In this reference technique , the radiation detector is disposed on the upper surface of the scintillator block, but may be disposed on the lower surface or on the upper surface and the lower surface. One scintillator block having such a structure constitutes a detection pixel. A two-dimensional image of the radiation can be obtained by detecting the fluorescence of the radiation incident on the detection pixel using the optical fiber bundles arranged in the lateral direction and the longitudinal direction of the side surface of the scintillator block described above. In addition, as an optical fiber, BCF-92 manufactured by USA Bicron, which is a wavelength shift fiber that is sensitive to a wavelength of 390 nm, can be used.

( Reference technology 13 )
As reference technique 13 , a two-dimensional radiation image detector according to the present invention will be described with reference to FIG. In the present invention, rectangular fluorescent light collecting blocks having a transmittance sufficient to transmit the fluorescence wavelength are arranged in a plane in the horizontal direction and the vertical direction, and optical fiber bundles are arranged on opposite side surfaces of the respective rectangular fluorescent light collecting blocks in the vertical direction. And a radiation detector that emits fluorescence by radiation on the upper or lower surface of the fluorescent condensing block or on the upper and lower surfaces of the fluorescent condensing block. Fluorescence generated from the radiation detectors placed on the upper or lower surface of each rectangular fluorescent condensing block or on the upper and lower surfaces of each rectangular fluorescent condensing block is arranged on the vertical and lateral sides of the fluorescent condensing block. It is characterized by detecting with a fiber bundle and obtaining a two-dimensional image of radiation.

In this reference technique , quartz glass is used as a rectangular fluorescent light collecting block used as a material of a two-dimensional radiation image detector. Quartz glass has sufficient transmission performance for wavelengths of 300 nm or more. As an example , the size of one fluorescent light collecting block is a square having a width of 5 mm, a width of 5 mm, and a thickness of 2 mm. Ten fluorescent light collecting blocks are arranged on a plane in the horizontal direction and ten in the vertical direction. Two optical fibers having a thickness of 0.5 mm are arranged on the opposite side surfaces of the fluorescent light collecting block, and two optical fibers having a thickness of 0.5 mm are arranged on the opposite side surfaces in the vertical direction. On the upper surface of the fluorescent light collecting block, Al ₂ O ₃ or MgO, which is a fluorescent reflecting material conventionally used as a reflective material for reflecting fluorescence, is disposed on the lower surface of the fluorescent light collecting block. In the present reference technique , the radiation detector is disposed on the upper surface of the fluorescent light collecting block, but may be disposed on the lower surface or on the upper surface and the lower surface. A detection pixel is constituted by one fluorescent light collecting block having such a structure. A two-dimensional image of the radiation can be obtained by detecting the fluorescence of the radiation incident on the detection pixel using the optical fiber bundles arranged in the lateral direction and the longitudinal direction of the side surface of the fluorescent light collecting block described above. In addition, as an optical fiber, BCF-92 manufactured by USA Bicron, which is a wavelength shift fiber that is sensitive to a wavelength of 390 nm, can be used.

( Reference Technology 14 )
As a reference technique 14 , a two-dimensional radiation image detector according to the present invention will be described with reference to FIG. According to the present invention, rectangular wavelength shifter blocks having a function of shifting the fluorescence wavelength to another wavelength are arranged in a plane in the horizontal direction and the vertical direction, respectively, and optical fiber bundles are arranged on opposite side surfaces of each rectangular wavelength shifter block in the vertical direction. In addition, optical fiber bundles are arranged on the opposite side surfaces of each rectangular wavelength shifter block in the horizontal direction, and radiation detectors that generate fluorescence by radiation are arranged on the upper surface, lower surface, or both upper and lower surfaces of the wavelength shifter block. The fluorescence generated from the radiation detectors arranged on the top, bottom or top and bottom surfaces of each rectangular wavelength shifter block is converted to another wavelength by the wavelength shift function of the wavelength shifter block, and the wavelength-converted fluorescence is converted to the wavelength shifter. Radiation is detected by optical fiber bundles placed on the vertical and lateral sides of the block. And it features a to obtain a two-dimensional image.

In this reference technique , a plastic wavelength shifter is used as a rectangular wavelength shifter block used as a material for a two-dimensional radiation image detector. As a rectangular wavelength shifter block used as a fluorescent light condensing material of the two-dimensional radiation image detector, a plastic wavelength shifter BC-484 manufactured by Bikinron, USA, which is a plastic wavelength shifter, is used. This plastic wavelength shifter can efficiently convert the wavelength to 434 nm fluorescence sufficiently with respect to the wavelength of 370 nm. As an example , the size of one wavelength shifter block is a square having a width of 5 mm, a width of 5 mm, and a thickness of 2 mm. Ten wavelength shifter blocks are arranged on a plane in the horizontal direction and ten in the vertical direction. Two optical fibers having a thickness of 0.5 mm are arranged on the side surfaces opposite to each other in the wavelength shifter block, and two optical fibers having a thickness of 0.5 mm are arranged on the side surfaces in the vertical direction. On the upper surface of the wavelength shifter block, Al ₂ O ₃ or MgO, which is a fluorescent reflection material conventionally used as a reflection material for reflecting fluorescence, is disposed on the lower surface of the wavelength shifter block. In this reference technique , the radiation detector is disposed on the upper surface of the wavelength shifter block, but may be disposed on the lower surface or on the upper and lower surfaces. A detection pixel is constituted by one wavelength shifter block having such a structure. A two-dimensional image of the radiation can be obtained by detecting the fluorescence of the radiation incident on the detection pixel using the optical fiber bundles arranged in the lateral direction and the longitudinal direction of the side surface of the wavelength shifter block described above. As the optical fiber, Y-7 or Y-11 manufactured by Kuraray Co., Ltd., which is a wavelength shift fiber sensitive to 434 nm, can be used.

( Reference technology 15 )
As a reference technique 15 , a two-dimensional radiation image detector according to the present invention will be described with reference to FIG. In the present invention, the rectangular scintillator block, the fluorescence condensing block, and the wavelength shifter block described in Reference Techniques 12, 13, and 14 are provided with optical fiber bundles on the opposite side surfaces of the rectangular blocks in the vertical and horizontal directions. Are arranged so that every other vertical and horizontal optical fiber bundles are vertically crossed as shown in FIG. 21, and by detecting the fluorescence of the radiation incident in the detection pixel, It is characterized by obtaining a two-dimensional image of radiation. With such a structure, the fluorescence detection efficiency by the optical fiber bundle can be increased.

( Example 4 )
As Example 4 , a two-dimensional neutron image detector according to the present invention will be described with reference to FIG. The present invention uses a scintillator containing at least one element of ⁶ Li, ¹⁰ B, or Gd, which is a neutron converter, as a scintillator in Examples 1 to 4 and Reference Techniques 1 to 14 , and a neutron converter as a neutron detector It is a two-dimensional neutron image detector characterized by obtaining a two-dimensional image of neutrons by using a material containing at least one element of ⁶ Li, ¹⁰ B, or Gd.

And this embodiment describes an example of applying the present invention to reference technology 6. In this embodiment, a ⁶ Li glass scintillator containing ⁶ Li which is a neutron converter is used as a scintillator used as a material of the two-dimensional neutron image detector. As the present glass scintillator, a GS20 ⁶ Li glass scintillator manufactured by Bikinron of the United States having a content of ⁶ Li of 6.6% can be used. The fluorescence lifetime is 60 ns, and the fluorescence wavelength is 390 nm. As an example, the scintillator plate has a width of 200 m, a vertical width of 200 mm, and a thickness of 2 mm. Using a diamond cutter or the like, grooves having a width of 0.6 mm and a depth of 1.5 mm are formed in the scintillator plate at intervals of 5 mm in the horizontal direction and at intervals of 5 mm in the vertical direction. Three optical fibers having a thickness of 0.5 mm are arranged in the horizontal groove, and Al ₂ O ₃ which is a fluorescent reflecting material conventionally used as a reflecting material for reflecting fluorescence is arranged in the vertical groove. Embed MgO or the like. A detection pixel is configured which is divided into a horizontal groove and a vertical groove. As the neutron detector, a neutron detection medium in which ⁶ LiF, which is a neutron converter, is mixed with YAlO ₃ : Ce powder having a fluorescence wavelength of 370 nm, which is approximately the same wavelength as 390 nm, which is the fluorescence wavelength of ⁶ Li glass scintillator, can be used. A detection pixel is composed of a scintillator sensitive to one neutron having such a structure.

  Therefore, the fluorescence by the neutrons incident on the detection pixel and the fluorescence by the neutrons incident on the neutron detector by the optical fiber bundle arranged in the groove and the optical fiber bundle having ten optical fibers having a thickness of 0.5 mm on the upper surface. , A two-dimensional image of neutrons can be obtained efficiently. As the optical fiber, BCF-99-XX (special order) manufactured by Bicron, USA, which is a wavelength shift fiber sensitive to wavelengths from 370 nm to 390 nm, can be used.

( Reference Technology 16 )
As a reference technique 16 , a two-dimensional radiation image detector according to the present invention will be described with reference to FIG. In the present invention, a liquid scintillator that generates fluorescence when radiation is incident is used as a detection medium, and a reflector block made of a material that can reflect fluorescence is arranged in a detection container that can seal off the liquid scintillator. After that, the liquid scintillator is filled, and the fluorescence generated from the liquid scintillator in each lattice when the radiation is incident is detected by an optical fiber bundle arranged so as to be orthogonal to the upper and lower portions of each lattice. It is characterized by obtaining an image.

In this reference technique , BC-501A manufactured by Bicron is used as a liquid scintillator used as a material for a two-dimensional radiation image detector. The fluorescence lifetime is 3.2 ns and the fluorescence wavelength is 425 nm. As an example , a detection container having a horizontal width of 10 cm and a vertical width of 10 cm is used as a detection container for sealing the liquid scintillator. The internal height is 4 mm. A rectangular insertion opening for arranging wavelength shift fibers in parallel is provided on one lateral side surface of the upper portion of the detection container. In addition, a rectangular insertion port for arranging the wavelength shift fibers in parallel is provided on the vertical side surface of the lower part of the detection container. The detection container can be made of aluminum or stainless steel. In addition, as a grid-like reflection block having one section of 5 mm, an overall size having a horizontal width of 10 cm, a vertical width of 10 cm, and a height of 2.8 mm is used. The reflection block can be made of an aluminum plate whose surface is well polished. In the case of this reference technique , 200 wavelength-shifted fibers having a thickness of 0.5 mm are arranged in parallel and arranged in all the detection containers using a rectangular optical fiber insertion opening opened on the lateral side surface of the upper part of the detection container. In addition, in the case of this reference technique , 200 wavelength-shifted fibers having a thickness of 0.5 mm are arranged in parallel and arranged in all the detection containers using a rectangular optical fiber insertion opening opened in the vertical side surface of the lower part of the detection container. . Since there is a gap of 3 mm between the wavelength shift fiber bundle disposed in the upper part and the wavelength shift fiber bundle disposed in the lower part, the above-described reflector block is placed in this space. Five optical fibers in the horizontal and vertical directions will detect the fluorescence generated from the detection pixels created by the reflector block grating. As the optical fiber, BCF-91 manufactured by Bicron, USA, which is a wavelength shift fiber sensitive to a wavelength of 425 nm, can be used. After the liquid scintillator is placed in the detection container, the fluorescence of the radiation incident on the liquid scintillator detection pixel is detected by using the horizontal and vertical optical fiber bundles corresponding to each detection pixel. A two-dimensional image can be obtained. In this reference technology , BC-501A manufactured by Bikeron Co., Ltd. was used as the liquid scintillator. However, BC-551 or BC-553 in which lead or tin is mixed with the liquid scintillator for X-rays can be used according to the purpose. .

( Reference Technology 17 )
As reference technique 17 , a two-dimensional radiation image detector according to the present invention will be described with reference to FIG. The present invention uses a liquid scintillator that generates fluorescence when radiation enters as a detection medium, fills the liquid scintillator in a detection container capable of sealing off the liquid scintillator, and bundles optical fiber bundles so as to be orthogonal to the vertical and horizontal directions. One or more optical fiber detection blocks arranged in a lattice pattern at regular intervals are placed one on top of the other in the thickness direction of the detection container, and the fluorescence generated from the liquid scintillator in each lattice when radiation is incident is placed on the optical fiber detection It is characterized by obtaining a two-dimensional image of radiation detected by a block.

In this reference technique , BC-501A manufactured by Bicron is used as a liquid scintillator used as a material for a two-dimensional radiation image detector. The fluorescence lifetime is 3.2 ns and the fluorescence wavelength is 425 nm. As an example , a detection container having a horizontal width of 10 cm and a vertical width of 10 cm is used as a detection container for sealing the liquid scintillator. The thickness is 2 mm. An insertion port that matches the shape of the optical fiber is opened at intervals of 5 mm on the lateral side surface of the upper part of the detection container. In addition, an insertion port that matches the shape of the optical fiber is opened at intervals of 5 mm on the side surface in the vertical direction below the detection container. In the case of this reference technique , a wavelength-shifted fiber having a square shape of 1 mm is used as the wavelength-shifted fiber. The detection container can be made of aluminum or stainless steel. In the case of this reference technique , square-shaped wavelength shift fibers having a thickness of 1 mm are arranged at intervals of 5 mm and arranged in all the detection containers using a rectangular optical fiber insertion opening opened in the lateral side surface of the upper part of the detection container. In addition, square-shaped wavelength shift fibers having a thickness of 1 mm are arranged at intervals of 5 mm and arranged in all the detection containers using a rectangular optical fiber insertion opening opened in the vertical side surface of the lower part of the detection container. As the optical fiber, BCF-91 manufactured by Bicron, USA, which is a wavelength shift fiber sensitive to a wavelength of 425 nm, can be used. After the liquid scintillator is placed in the detection container, the fluorescence of the radiation incident on the liquid scintillator detection pixel is detected using the horizontal and vertical optical fibers corresponding to each detection pixel, so that the radiation 2 A dimensional image can be obtained.

( Reference Technology 18 )
As a reference technique 18 , a two-dimensional radiation image detector according to the present invention will be described with reference to FIG. In the present invention, a radiation detector that emits fluorescence when radiation is incident on the upper part or the lower part or both the upper part and the lower part in the detection container that can store the liquid scintillator in the reference technique 17 is disposed, and Fluorescence generated from the liquid scintillator in each grating when the radiation is incident is detected by an optical fiber bundle, and a two-dimensional image of the radiation is obtained.

In this reference technique , BC-501A manufactured by Bicron is used as a liquid scintillator used as a material for a two-dimensional radiation image detector. The fluorescence lifetime is 3.2 ns and the fluorescence wavelength is 425 nm. As an example , a detection container having a horizontal width of 10 cm and a vertical width of 10 cm is used as a detection container for sealing the liquid scintillator. The internal height is 2.6 mm. In this reference technique , a radiation detector that generates fluorescence when radiation is incident on both the upper and lower surfaces of the detection container is disposed. As the radiation detector, Y ₂ SiO ₅ : Ce, which is a phosphor that emits substantially the same 410 nm as the fluorescence wavelength of the liquid scintillator, is used. This phosphor is disposed on both the upper and lower sides of the detection container with a thickness of 200 μm.

An insertion port that matches the shape of the optical fiber is opened at intervals of 5 mm on the side surface in the horizontal direction at a position lowered by 300 μm from the inner surface of the upper part of the detection container. In addition, an insertion port that matches the shape of the optical fiber is opened at intervals of 5 mm on the side surface in the vertical direction at a position 300 μm above the inner surface of the upper part of the detection container. In the case of this reference technique , a wavelength-shifted fiber having a square shape of 1 mm is used as the wavelength-shifted fiber. The detection container can be made of aluminum or stainless steel. In the case of this reference technique , square-shaped wavelength shift fibers having a thickness of 1 mm are arranged at intervals of 5 mm and arranged in all the detection containers using a rectangular optical fiber insertion opening opened in the lateral side surface of the upper part of the detection container. In addition, square-shaped wavelength shift fibers having a thickness of 1 mm are arranged at intervals of 5 mm and arranged in all the detection containers using a rectangular optical fiber insertion opening opened in the vertical side surface of the lower part of the detection container. As the optical fiber, BCF-91 manufactured by Bicron, USA, which is a wavelength shift fiber sensitive to a wavelength of 425 nm, can be used. Fluorescence and liquid scintillator detection from radiation detectors placed on the upper and lower surfaces of the detection container using the horizontal and vertical optical fibers corresponding to each detection pixel after the liquid scintillator is placed in the detection container By detecting the fluorescence of the radiation incident on the pixel, a two-dimensional image of the radiation can be obtained.

( Reference Technology 19 )
As reference technique 19 , a two-dimensional radiation image detector according to the present invention will be described with reference to FIG. The present invention provides a two-dimensional structure having a structure in which a liquid scintillator circulation mechanism including at least a valve, a pipe, and a pump is added to circulate the liquid scintillator in a detection container that can store the liquid scintillator in the above reference technique 16-18 . Radiation image detector. When a large amount of radiation comes, the amount of light emitted from the liquid scintillator decreases due to radiation damage. Moreover, since radiation does not come uniformly, the detection sensitivity is not uniform. In such a case, uniformity of detection sensitivity or deterioration of sensitivity can be prevented by circulating the liquid scintillator using a pump. Naturally, in the case of this structure, it can be easily replaced when it is completely deteriorated.

( Reference Technology 20 )
As a reference technique 20 , a two-dimensional neutron image detector according to the present invention will be described with reference to FIG. The present invention relates to the above-described Reference Technique 16-19 , in which a liquid scintillator is mixed with a material containing at least one element of ⁶ Li, ¹⁰ B, or Gd, which is a neutron converter, and combined with a radiation detector. Is a two-dimensional neutron image detector characterized by mixing a radiation detector with a material containing at least one element of ⁶ Li, ¹⁰ B or Gd, which is a neutron converter, to obtain a two-dimensional image of neutrons. is there.

In this reference technology , two-dimensional neutron imaging will be described based on reference technology 18 . As a liquid scintillator used as a material for the neutron detector, BC-521 manufactured by Bicron is used. This liquid scintillator contains 1% of Gd which is a neutron converter. The fluorescence lifetime is 4 ns and the fluorescence wavelength is 425 nm. As an example , a detection container having a horizontal width of 10 cm and a vertical width of 10 cm is used as a detection container for sealing the liquid scintillator. The internal height is 2.6 mm. In this reference technique , a radiation detector that generates fluorescence when radiation is incident on both the upper and lower surfaces of the detection container is disposed. As the neutron detector, a detection medium in which ⁶ LiF is mixed with Y ₂ SiO ₅ : Ce, which is a phosphor emitting substantially the same 410 nm as the fluorescence wavelength of the liquid scintillator, is used. The neutron detector is disposed on both the upper and lower surfaces of the detection container with a thickness of 200 μm.

An insertion port that matches the shape of the optical fiber is opened at intervals of 5 mm on the side surface in the horizontal direction at a position lowered by 300 μm from the inner surface of the upper part of the detection container. In addition, an insertion port that matches the shape of the optical fiber is opened at intervals of 5 mm on the side surface in the vertical direction at a location 300 μm above the inner surface of the upper part of the detection container. In the case of this reference technique , a wavelength-shifted fiber having a square shape of 1 mm is used as the wavelength-shifted fiber. The detection container can be made of aluminum or stainless steel. In the case of this reference technique , square-shaped wavelength shift fibers having a thickness of 1 mm are arranged at intervals of 5 mm and arranged in all the detection containers using a rectangular optical fiber insertion opening opened in the lateral side surface of the upper part of the detection container. In addition, square-shaped wavelength shift fibers having a thickness of 1 mm are arranged at intervals of 5 mm and arranged in all the detection containers using a rectangular optical fiber insertion opening opened in the vertical side surface of the lower part of the detection container. As the optical fiber, BCF-91 manufactured by Bicron, USA, which is a wavelength shift fiber sensitive to a wavelength of 425 nm, can be used. Fluorescence and liquid scintillator detection from neutron detectors placed on the upper and lower surfaces of the detection container using the horizontal and vertical optical fibers corresponding to each detection pixel after the liquid scintillator is placed in the detection container By detecting the fluorescence of the radiation incident on the pixel, a two-dimensional image of neutrons can be obtained. By adopting this structure, a neutron detector having a different neutron energy dependency of the neutron capture cross section can be used as the neutron converter, so that the sensitivity to neutron energy can be flattened.

In this reference technology , as a liquid scintillator as a material for the neutron detector, BC-521 manufactured by Bikeron is used, but BC-523 or BC-523A containing B or ¹⁰ B can also be used.

( Example 5 )
As a fifth embodiment, a two-dimensional radiation image detector according to the present invention will be described with reference to FIG. The present invention uses a streak camera as a photodetector for detecting the fluorescence emitted from the optical fiber bundle in the above-described Examples 1-4 and 1-20 , and is emitted from the optical fiber bundle detected by the streak camera. It is a two-dimensional radiation image detector or a two-dimensional neutron image detector characterized by acquiring a two-dimensional image of radiation or neutrons by analyzing time series data of fluorescence based on a simultaneous measurement method. In this embodiment, the case where the present invention is applied to the reference technique 1 will be described. In the present embodiment, as the scintillator plate, plastic scintillator BC-414 manufactured by Bikinron, USA, which has been conventionally used as a detection medium for ionizing radiation such as X-rays or α rays, can be used. The fluorescence lifetime is 1.8 and the fluorescence wavelength is 392 nm. As an example, the scintillator plate has a width of 100 m, a vertical width of 100 mm, and a thickness of 2 mm. A groove having a width of 0.5 mm and a depth of 1.5 mm is formed in the scintillator plate at intervals of 2 mm in the horizontal direction and at intervals of 2 mm in the vertical direction, and Al ₂ O ₃ or MgO, which is a fluorescent reflecting material conventionally used, is embedded. Thus, a detection pixel divided into horizontal and vertical grooves is formed.

  In this two-dimensional radiation image detector, the fluorescence of the radiation incident on the detection pixel, which is a conventional method, is converted into an optical fiber bundle in the X direction on the upper surface of the two-dimensional radiation image detector and an optical fiber bundle in the Y direction on the lower surface. A two-dimensional radiation image detector can be configured by arranging in a grid and applying the coincidence counting method. As the optical fiber bundle, BCFRON-92 manufactured by Bikeron Co., Ltd. suitable for the fluorescence wavelength of the plastic scintillator BC-414 can be used. After the wavelength-shifted optical fiber bundles in the X direction and the Y direction are arranged side by side in parallel, the width is adjusted to the sensitive lateral width of the streak tube by an optical system such as a lens. As the streak tube, it is necessary to select a type having a wide sensitive portion as wide as possible, and Hamamatsu Photonics C7700 having a length of 18 mm as a sensitive length can be used. The wavelength-shifted fluorescence signal that has been reduced by the lens that is the optical system and entered the sensitive part of the streak tube, the deflection voltage of the deflection plate of the streak tube at a certain time interval by the streak tube control circuit, and the vertical direction of the streak tube Sweep and detect for the time corresponding to the width. When the plastic scintillator BC-414 is used as the radiation detector, the fluorescence lifetime is 1.8 ns, so the time 10 ns, which is about five times as long as that, is used as the time resolution. By setting the time several times as long as the fluorescence lifetime in this way, it is possible to integrate and detect almost all the fluorescence generated when radiation is incident. A streak image can be obtained on the phosphor screen of the streak tube after sweeping for a time corresponding to the vertical width, and this streak image is captured by an imaging camera. As an imaging camera, a CCD camera having detection characteristics of horizontal 1000 pixels and vertical 1000 pixels can be used. At this time, since the number of pixels on the vertical axis of the CCD camera is 1000 pixels, the effective sweep time is 10 μs by multiplying 10 ns by 1000. By digitizing the video signal of the CCD camera by a signal processing / analyzing device, time-series data of two optical fiber bundles can be obtained. This data is stored in a storage device in the signal processing / analysis device.

  The stored time-series data of the two emission signal intensities of the optical fiber bundle is analyzed by a signal processing / analysis device. There are two analysis processing methods. One is to analyze the time-series data of the emission signal intensity in the photon counting mode, that is, the mode in which the photon enters when the emission signal intensity value is larger than a certain set value, and enter the horizontal and vertical directions simultaneously. In this case, the position is used as the radiation incident position. The other is a mode in which the value of the emission signal intensity is analyzed in two or more stages, and analysis is possible even when two or more radiations are incident on the detection pixels in the horizontal direction or the vertical direction at the same time. In this case, the analysis time increases. Further, in the present embodiment, the time resolution of coincidence is 10 ns, and the position can be specified by comparing one pixel before and after.

  As described above, since the multi-channel two-dimensional light detection can be easily performed at high speed by using the streak camera, it can be performed in a short time using a two-dimensional radiation image detector or a two-dimensional neutron image detector and a time-of-flight method. This is particularly useful for studies that require high count rate processing.

( Reference Technology 21 )
As reference technique 21 , a two-dimensional radiation image detector according to the present invention will be described with reference to FIG. The present invention uses a scintillator, a liquid scintillator or a phosphor as a detection medium, and detects fluorescence generated from these detection media using a transverse optical fiber bundle and a longitudinal optical fiber bundle arranged in an orthogonal grid pattern. In a two-dimensional radiation image detector or a two-dimensional neutron image detector for determining the incident position of radiation or neutron, the fluorescence emitted from the transverse optical fiber bundle and the longitudinal optical fiber bundle is detected using a photodetector and a pulse height discriminator. When photon detection is performed and a radiation image is constructed based on the output lateral photon detection signal and longitudinal photon detection signal, it can be retriggered based on the timing pulse signal output from the wave height discriminator. A scintillator, a liquid scintillator or a detection medium using a retriggerable pulse signal generator that generates a pulse Based on the Poisson distribution corresponding to the fluorescence lifetime of the light body, the generated pulse signal is generated and the two-dimensional image of radiation or neutron is acquired based on the generated pulse signal. It is a two-dimensional radiation image detector or a two-dimensional neutron image detector. As shown in FIG. 29, in the present invention, when a radiation image is formed based on a lateral photomultiplier tube output signal and a vertical photomultiplier tube output signal created based on the fluorescence generated in the scintillator. Poisson corresponding to the fluorescence lifetime of the detection medium using a retriggerable pulse signal generator that generates a pulse in a retrigtable state based on a timing pulse signal output from a pulse height discriminator not shown in the figure A pulse signal is generated with a time width determined based on the distribution. Using the generated retriggerable horizontal constant time width pulse generator output signal and the retriggerable vertical constant time width pulse generator output signal, perform simultaneous counting and output the coincidence circuit output result Obtain a two-dimensional radiation image. At this time, the coincidence efficiency can be increased most efficiently by setting the time width to substantially the same time as the fluorescence lifetime.

  On the other hand, in the conventional method, since it is necessary to increase the coincidence efficiency, a time width of at least twice the fluorescence lifetime is set. For this reason, the pulse time width used for the coincidence counting can be shortened in the present invention rather than using the constant time width pulse generator that generates the constant time width of the conventional method, so that a high counting rate can be achieved. . When the time width is 80 ns or more, a retriggerable constant time width pulse generator can be easily produced by a retriggerable pulse generator element such as SN74122 or SN74123 which is a commercially available TTL integrated circuit element. .

( Reference Technology 22 )
As a reference technique 22 , a two-dimensional radiation image detector according to the present invention will be described with reference to FIG. The present invention uses a scintillator, a liquid scintillator or a phosphor as a detection medium, and detects fluorescence generated from these detection media using a transverse optical fiber bundle and a longitudinal optical fiber bundle arranged in an orthogonal grid pattern. In a two-dimensional radiation image detector or a two-dimensional neutron image detector for determining the incident position of radiation or neutrons, the fluorescence emitted from the transverse optical fiber bundle and the longitudinal optical fiber bundle is detected using a photodetector and a pulse height discriminator. A pulse signal generator is used based on the timing pulse signal output from the wave height discriminator when photon detection is performed and a radiation image is constructed based on the output lateral photon detection signal and longitudinal photon detection signal. Poisson using a pulse signal with a fixed time width generated by a retriggerable pulse signal generator A pulse signal generated with a time width determined based on the cloth is recorded as a time-series signal using a parallel signal input circuit and a signal recording / analysis device, and the recorded time-series signal is simultaneously recorded using a signal recording / analysis device. It is a two-dimensional radiation image detector or a two-dimensional neutron image detector characterized by obtaining a two-dimensional image of radiation or neutron by analyzing based on a measurement method.

As this reference technique , an example in which the present invention is applied to a two-dimensional neutron image detector characterized by obtaining a two-dimensional image of a neutron having a structure configured based on Example 4 will be described. For the horizontal and vertical directions, 6 × 6 scintillator blocks are used as shown in FIG. Further, a pulse that is generated with a time width determined based on a Poisson distribution using a retriggerable constant time width pulse generator that can be retriggered based on the timing pulse signal output from the pulse height discriminator described in Reference Technique 21. The signal is used as a coincidence signal for position determination.

The fluorescence generated in the scintillator of the two-dimensional neutron image detector is converted into an electrical signal using a multichannel photomultiplier tube. As a multi-channel photomultiplier tube, a 16-channel photomultiplier tube H6568 made by Hamamatsu Photonics can be used. A timing pulse signal is generated by a wave height discriminator using this electric signal. Based on this timing pulse signal, the time width is determined based on the Poisson distribution corresponding to the fluorescence lifetime of the detection medium using a retriggerable constant time width pulse generator that generates pulses in a retriggerable state. The horizontal direction photon detection signal and the vertical direction photon detection signal are generated. These signals are taken into a digital signal collecting device as a signal recording device using a parallel interface as a signal input circuit in parallel at high speed and recorded in a data recording device. As the parallel interface, National Instrument's 32-channel data recording board PCI-DIO-32HS or the like can be used. In FIG. 30, the parallel interface is prepared separately in the horizontal direction and the vertical direction, but can be processed by one parallel interface board. In the case of this board, pulse signals can be recorded as time series signals at intervals of 100 ns. It is possible to easily obtain a two-dimensional image of radiation or neutrons by analyzing the recorded time series signals using a data analysis device based on the coincidence counting method as shown in Reference Technique 21 .

Claims (6)

  The rectangular scintillator blocks are arranged in a plane in the horizontal direction and the vertical direction, optical fiber bundles are arranged on the opposite side surfaces of each rectangular scintillator block in the vertical direction, reflectors are arranged on the opposite side surfaces in the horizontal direction, and Each reflector is arranged on the upper surface of the scintillator block, and the optical fiber bundle is arranged in the lateral direction that is perpendicular to the optical fiber bundle arranged on the side surface on the lower surface of the scintillator block arranged in a plane. A two-dimensional image characterized in that a two-dimensional image of radiation is obtained by detecting fluorescence of radiation incident on the scintillator block with an optical fiber bundle disposed on a side surface of the scintillator block and an optical fiber bundle disposed on a lower surface. Radiation image detector.   Rectangular scintillator blocks are arranged in a plane in the horizontal and vertical directions, optical fiber bundles are arranged on the opposite side surfaces of each rectangular scintillator block in the vertical direction, and reflectors are arranged on the opposite side surfaces in the horizontal direction. The scintillator blocks arranged side by side have a structure in which optical fiber bundles are arranged in a lateral direction that is perpendicular to the optical fiber bundles arranged on the side surfaces on the upper and lower surfaces, and the fluorescence of radiation incident on each rectangular scintillator block is A two-dimensional radiation image detector characterized by obtaining a two-dimensional image of radiation by detecting with an optical fiber bundle disposed on a side surface of a scintillator block and optical fiber bundles disposed on an upper surface and a lower surface.   The rectangular scintillator blocks are arranged in a plane in the horizontal direction and the vertical direction, optical fiber bundles are arranged on the opposite side surfaces of each rectangular scintillator block in the vertical direction, reflectors are arranged on the opposite side surfaces in the horizontal direction, and A radiation detector that emits fluorescence by radiation is disposed on the upper surface of the scintillator block, and an optical fiber bundle in a lateral direction that is perpendicular to the optical fiber bundle disposed on the side surface on the lower surface of the scintillator block arranged in a plane. And the fluorescence of the radiation incident on each rectangular scintillator block and the fluorescence generated from the radiation detector are detected by the optical fiber bundle disposed on the side surface of the scintillator block and the optical fiber bundle disposed on the lower surface. A two-dimensional radiation image detector characterized by obtaining a two-dimensional image of radiation. 2. The two-dimensional image of neutrons according to claim 1, wherein the scintillator block is provided with a neutron converter material containing at least one element of ⁶ Li, ¹⁰ B, or Gd, thereby obtaining a two-dimensional image of neutrons. Dimensional neutron image detector. The radiation detector is ⁶ Li, ^Ten The two-dimensional neutron image detector according to claim 3, wherein a two-dimensional image of neutrons is obtained by providing a neutron converter material containing at least one element of B or Gd. A streak camera is used as a photodetector for detecting fluorescence emitted from the optical fiber bundle, and time series data of fluorescence emitted from the optical fiber bundle detected by the streak camera is analyzed based on a simultaneous measurement method. The two-dimensional radiation image detector or the two-dimensional neutron image detector according to any one of claims 1 to 5 , wherein a two-dimensional image of radiation or neutron is acquired by the above.

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