JP2001311777A - Thin radiation surface contamination detector - Google Patents
Thin radiation surface contamination detectorInfo
- Publication number
- JP2001311777A JP2001311777A JP2000132100A JP2000132100A JP2001311777A JP 2001311777 A JP2001311777 A JP 2001311777A JP 2000132100 A JP2000132100 A JP 2000132100A JP 2000132100 A JP2000132100 A JP 2000132100A JP 2001311777 A JP2001311777 A JP 2001311777A
- Authority
- JP
- Japan
- Prior art keywords
- fibers
- fiber
- scintillation
- wavelength conversion
- light
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、シンチレーション
ファイバと波長変換ファイバとを近接配置した薄型の放
射線表面汚染検出器に関するものである。この放射線表
面汚染検出器は、原子力施設、放射性物質取扱施設、加
速器使用施設などにおける大面積の放射線（特にγ線）
表面汚染モニタとして有用である。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin radiation surface contamination detector in which a scintillation fiber and a wavelength conversion fiber are arranged close to each other. This radiation surface contamination detector is used for large area radiation (especially gamma rays) in nuclear facilities, facilities handling radioactive materials, facilities using accelerators, etc.
Useful as a surface contamination monitor.
【０００２】[0002]
【従来の技術】表面汚染を測定するための大面積の放射
線検出器としては、従来、複数本の筒状のＧＭ計数管を
並設した構造、あるいはプラスチックシンチレータと筒
状の光電子増倍管を組み合わせた構造などがあった。こ
のような構造は、面積の大きなものは製作可能であった
が、厚みのある大きな筐体の装置となってしまい、身体
汚染モニタ（体表面モニタ）や物品搬出モニタに適用し
た場合、大型となり、設置場所の制約、装置移動等に問
題があった。また、フットモニタとして使用した場合に
は、段差が生じ、歩行に支障を与える欠点もあった。2. Description of the Related Art Conventionally, as a large-area radiation detector for measuring surface contamination, a structure in which a plurality of cylindrical GM counters are juxtaposed, or a plastic scintillator and a cylindrical photomultiplier are conventionally used. There were combined structures. Although such a structure can be manufactured with a large area, it becomes a device with a large and thick housing, and when applied to a body contamination monitor (body surface monitor) or an article carry-out monitor, it becomes large. In addition, there are problems with installation location restrictions, equipment movement, and the like. In addition, when used as a foot monitor, there is a drawback that a step is generated and walking is hindered.
【０００３】そこで近年、多数本のシンチレーションフ
ァイバを平行に並べ、それらの端部を束ねて光電子増倍
管に接続する構造の放射線検出器が提案されている。ま
た、多数本のシンチレーションファイバをＵ型に折り返
して、光電子増倍管を片側に設置する構成も提案されて
いる。In recent years, there has been proposed a radiation detector having a structure in which a large number of scintillation fibers are arranged in parallel, their ends are bundled and connected to a photomultiplier tube. There has also been proposed a configuration in which a large number of scintillation fibers are folded back into a U-shape and a photomultiplier is installed on one side.
【０００４】[0004]
【発明が解決しようとする課題】このような多数本のシ
ンチレーションファイバを平行に配列した構造は、薄型
の放射線表面汚染検出器に適している。しかし、原子力
施設を管理するために十分な検出感度が得られない可能
性があった。Such a structure in which a number of scintillation fibers are arranged in parallel is suitable for a thin radiation surface contamination detector. However, there was a possibility that sufficient detection sensitivity could not be obtained for managing nuclear facilities.
【０００５】シンチレーションファイバは、図６に示す
ように、通常の光ファイバと同様、中心に位置するコア
１０とそれを取り囲むクラッド１２とからなるが、コア
１０に放射線に反応するプラスチックシンチレータを用
いたものである。発光原理は他の有機シンチレータと同
様であり、放射線による励起作用によりシンチレーショ
ン光が発生する。放射線によりコア１０で発生した光
は、通常の光ファイバと同様に、コア１０とクラッド１
２の境界での全反射によって、シンチレーションファイ
バ自身を光パイプ（ライトガイド）として伝播し、端部
に位置する光電子増倍管に到達して検出される。As shown in FIG. 6, the scintillation fiber comprises a core 10 located at the center and a clad 12 surrounding the core, as in a normal optical fiber. A plastic scintillator which responds to radiation is used for the core 10. Things. The principle of light emission is the same as that of other organic scintillators, and scintillation light is generated by the action of excitation by radiation. The light generated in the core 10 due to the radiation is transmitted to the core 10 and
By the total reflection at the boundary of No. 2, the scintillation fiber itself propagates as a light pipe (light guide), and reaches the photomultiplier tube located at the end to be detected.
【０００６】図６のＡに示すように、コア１０の屈折率
ｎ1 は、クラッドの屈折率ｎ2 よりも大きく設定されて
おり（ｎ1 ＞ｎ2 ）、臨界角θC θC ＝sin -1（ｎ2 ／ｎ1 ） に対して、コアからクラッドへの入射角θA が、θA ＞
θC であれば光は境界面で反射し、コアからクラッドへ
の入射角θB が、θB ＜θC であれば光は外部に漏れ
る。従って、例えば中心軸上の発光は、コア１０とクラ
ッド１２による臨界角の円錐（図６のＢで、符号１４で
示す）内に放出された光のみが全反射を繰り返して伝播
し、ファイバ端部の光電子増倍管に到達する。しかし、
臨界角の円錐１４から外れた光は、ファイバ外に放出さ
れることになる。因みに、メーカカタログによれば、発
生したシンチレーション光のうち９０％以上がファイバ
外に漏れ出るとされている。つまり、光電子増倍管に到
達する光は、発生したシンチレーション光の１０％以下
ということになる。As shown in FIG. 6A, the refractive index n 1 of the core 10 is set to be larger than the refractive index n 2 of the cladding (n 1 > n 2 ), and the critical angle θ C θ C = sin -1 (n 2 / n 1 ), the incident angle θ A from the core to the cladding is θ A >
Light If theta C is reflected at the boundary surface, the incident angle theta B from the core to the cladding, light if θ B <θ C leaks to the outside. Therefore, for example, only light emitted within the cone of the critical angle (indicated by reference numeral 14 in FIG. 6B) by the core 10 and the clad 12 propagates by repeating total internal reflection, for example, on the central axis. Part of the photomultiplier tube. But,
Light deviating from the critical angle cone 14 will be emitted out of the fiber. Incidentally, according to the manufacturer's catalog, 90% or more of the generated scintillation light leaks out of the fiber. That is, the light reaching the photomultiplier tube is 10% or less of the generated scintillation light.
【０００７】従って、前述したように、このようなシン
チレーションファイバを配列しただけの放射線検出器
は、検出効率が悪く、必ずしも原子力施設を管理するの
に十分な感度が得られないという大きな問題があったの
である。Therefore, as described above, a radiation detector in which only such scintillation fibers are arranged has a serious problem that the detection efficiency is low and the sensitivity is not always sufficient to control a nuclear facility. It was.
【０００８】また、シンチレーションファイバを平行に
並べ、光電子増倍管を片側に配置するようにＵ型に折り
返す場合、曲率を変えて並べるように折り曲げると、最
も内側のファイバではかなり広い隙間が生じる。折り返
しの際のアールがあまりきつすぎると、ファイバが破損
したり、光の伝播損失が大きくなり、曲率を小さくでき
ないためである。このような隙間は不感ゾーンとなり、
そのため感度分布が一様にならない欠点が生じる。In the case where scintillation fibers are arranged in parallel and the photomultiplier tube is folded back into a U-shape so as to be arranged on one side, if the bends are arranged so that the curvature is changed, a considerably wide gap is generated in the innermost fiber. This is because if the radius is too tight at the time of folding, the fiber may be damaged or the propagation loss of light may increase, and the curvature may not be reduced. Such a gap becomes a dead zone,
For this reason, there is a disadvantage that the sensitivity distribution is not uniform.
【０００９】本発明の目的は、検出感度及びエネルギー
レスポンスが良好で、大面積化に適し、薄型化できるよ
うな放射線表面汚染検出器を提供することである。本発
明の他の目的は、ファイバをＵ型に折り返す際に隙間が
生じず、全てのファイバを均等間隔で配列でき、そのた
め検出感度分布を一様にできる薄型放射線表面汚染検出
器を提供することである。SUMMARY OF THE INVENTION An object of the present invention is to provide a radiation surface contamination detector which has good detection sensitivity and energy response, is suitable for a large area, and can be made thin. It is another object of the present invention to provide a thin radiation surface contamination detector which can arrange all the fibers at equal intervals without forming a gap when the fibers are folded into a U-shape, and thus can have a uniform detection sensitivity distribution. It is.
【００１０】[0010]
【課題を解決するための手段】本発明は、多数のシンチ
レーションファイバを平行に配列し、Ｕ型に折り返しフ
ァイバ両端を束ねて受光デバイスに接続することで、該
受光デバイスを片側に配置した構造の放射線表面汚染検
出器である。ここで本発明では、多数のシンチレーショ
ンファイバに近接して多数の波長変換ファイバを平行に
配列し、それら波長変換ファイバもＵ型に折り返しファ
イバ両端を束ねて受光デバイスに接続した構造とする。
受光デバイスとしては、光電子増倍管が好適である。The present invention has a structure in which a large number of scintillation fibers are arranged in parallel, folded in a U-shape, and both ends of the fibers are bundled and connected to a light receiving device, whereby the light receiving device is arranged on one side. Radiation surface contamination detector. Here, in the present invention, a number of wavelength conversion fibers are arranged in parallel in proximity to a number of scintillation fibers, and the wavelength conversion fibers are also folded back into a U-shape, and both ends of the fibers are bundled and connected to a light receiving device.
As a light receiving device, a photomultiplier tube is suitable.
【００１１】従来同様、シンチレーションファイバのコ
アにおいては、入射する放射線の励起作用によりシンチ
レーション光が発生し、臨界角内に放出された光はシン
チレーションファイバを伝播して端部の受光デバイスに
到達する。発生したシンチレーション光のうち、臨界角
から外れた光は、シンチレーションファイバ外に漏れ出
る。しかし、この漏れ光は周囲に近接配置されている波
長変換ファイバに入射する。波長変換ファイバでは、入
射した光が内部分子を励起し、励起状態から基底状態に
戻るときに、その分子固有の光を放出する。このように
して放出された光が、波長変換ファイバ内を伝播して端
部の受光デバイスに到達する。従って、シンチレーショ
ンファイバから漏れた光を波長変換ファイバにより再度
信号に寄与させることができ、検出効率が向上するので
ある。なお、本発明における波長変換ファイバは、その
波長変換のメカニズム（入射した光が内部分子を励起
し、励起状態から基底状態に戻るときに、その分子固有
の光を放出する現象）を利用してシンチレーションファ
イバから漏れた光を再度信号に寄与させるためのもので
あって、波長変換そのものを目的とするものではない。As in the prior art, in the core of the scintillation fiber, scintillation light is generated by the exciting action of the incident radiation, and the light emitted within the critical angle propagates through the scintillation fiber and reaches the light receiving device at the end. Of the generated scintillation light, light deviating from the critical angle leaks out of the scintillation fiber. However, this leaked light is incident on a wavelength conversion fiber disposed close to the periphery. In the wavelength conversion fiber, the incident light excites internal molecules and emits light unique to the molecules when returning from the excited state to the ground state. The light thus emitted propagates through the wavelength conversion fiber and reaches the light receiving device at the end. Therefore, the light leaked from the scintillation fiber can be made to contribute to the signal again by the wavelength conversion fiber, and the detection efficiency is improved. The wavelength conversion fiber according to the present invention utilizes the mechanism of wavelength conversion (a phenomenon in which incident light excites internal molecules and emits light unique to the molecules when returning from the excited state to the ground state). It is intended to contribute the light leaked from the scintillation fiber to the signal again, and is not intended for wavelength conversion itself.
【００１２】多数のシンチレーションファイバを近接配
列した層の上下両面に、多数の波長変換ファイバを近接
配列した層をそれぞれ配置して、全体を三層構造とする
のが好ましい。これによって検出感度は一層向上する。
また、各シンチレーションファイバと各波長変換ファイ
バは、全てのファイバをほぼ一定の曲率でほぼ同一面内
でＵ型に折り返えす。このようにすると、折り返し面内
でファイバ間隔が一定となり、大きな隙間が生じず、感
度分布を全面にわたって一様にできる。更に、多数のシ
ンチレーションファイバと多数の波長変換ファイバは、
光学接着剤により密着接合して一体化するのが好まし
い。It is preferable to arrange a plurality of layers in which a large number of wavelength conversion fibers are arranged in close proximity on the upper and lower surfaces of a layer in which a number of scintillation fibers are arranged in an adjacent manner, respectively, to form a three-layer structure as a whole. Thereby, the detection sensitivity is further improved.
Further, each of the scintillation fibers and each of the wavelength conversion fibers bends all the fibers into a U-shape in substantially the same plane with a substantially constant curvature. By doing so, the fiber spacing is constant in the folding plane, no large gap is generated, and the sensitivity distribution can be made uniform over the entire surface. Furthermore, many scintillation fibers and many wavelength conversion fibers
It is preferable to integrate them by closely bonding them with an optical adhesive.
【００１３】[0013]
【発明の実施の形態】計測装置などを収容した計測部ケ
ースと共通の底板上に、枠体を載置し、該枠体の内底部
に鉛板を敷設し、その上に、前記のようにしてＵ型に折
り返した三層構造のファイバ接合体を収容し、上面を検
出面ケースで覆うことにより、薄型の放射線表面汚染検
出器が構成できる。このように三層構造のファイバ接合
体を囲むような構造にすることで光漏れ防止を図ってい
る。底部の鉛板は、バックグラウンドを低減する機能を
果たす。BEST MODE FOR CARRYING OUT THE INVENTION A frame is placed on a common bottom plate with a measuring unit case accommodating a measuring device and the like, a lead plate is laid on the inner bottom of the frame, and the A thin radiation surface contamination detector can be configured by housing the three-layered fiber joined body folded into a U-shape and covering the upper surface with a detection surface case. Light leakage is prevented by forming a structure surrounding the three-layered fiber joined body in this way. The bottom lead plate serves to reduce the background.
【００１４】[0014]
【実施例】図１は本発明に係る薄型放射線表面汚染検出
器におけるファイバ配列状態の一例を示す説明図であ
る。図１のＡは、配列状態を分かり易くするために、フ
ァイバ同士の間隔を拡げた状態で模式的に表している。
多数のシンチレーションファイバ２０を平行に配列し、
その上下に、多数の波長変換ファイバ２２を平行に配列
して、全体を三層のシート状構造とする。つまり、下方
の波長変換ファイバの層−シンチレーションファイバの
層−上方の波長変換ファイバの層からなる三層構造であ
る。実際の積み重ね状態を図１のＢに示す。多数のシン
チレーションファイバ２０は、互いに近接するように一
列に配列され、多数の波長変換ファイバ２２も、互いに
近接するように一列に配列される。また、シンチレーシ
ョンファイバ２０と波長変換ファイバ２２も近接するよ
うに互いの配列ピッチを半ピッチずらせて配置する。FIG. 1 is an explanatory view showing an example of a fiber arrangement state in a thin radiation surface contamination detector according to the present invention. FIG. 1A schematically shows a state in which the distance between the fibers is widened for easy understanding of the arrangement state.
A number of scintillation fibers 20 are arranged in parallel,
Above and below, a number of wavelength conversion fibers 22 are arranged in parallel to form a three-layer sheet-like structure as a whole. That is, it has a three-layer structure including a lower wavelength conversion fiber layer, a scintillation fiber layer, and an upper wavelength conversion fiber layer. The actual stacked state is shown in FIG. The multiple scintillation fibers 20 are arranged in a row so as to be close to each other, and the multiple wavelength conversion fibers 22 are also arranged in a row so as to be close to each other. The scintillation fiber 20 and the wavelength conversion fiber 22 are also arranged so that the arrangement pitch thereof is shifted by a half pitch so as to be close to each other.
【００１５】シンチレーションファイバ２０は、図６に
示したのと同様、中心に位置するコアを周囲のクラッド
で覆う構造であり、コアのみが放射線に反応するプラス
チックシンチレータからなる。波長変換ファイバ２２
は、コアとクラッドからなり、入射した光の波長をコア
で変換するものであるが、ここではファイバの外側から
入射した光をファイバ内を伝播する光に変える機能を果
たすものとして使用している。実施例で使用した波長変
換ファイバは、波長４２０nmの光を波長４８０nmの光に
変換するタイプである。変換する波長を、端部に位置す
る受光デバイスの最適感度に一致させれば、検出器全体
としての検出感度を更に向上させることができる。例え
ば、光をフォトダイオードで受光する場合には、このよ
うに波長を変換（４２０→４８０nm）した方が検出効率
が向上する。As shown in FIG. 6, the scintillation fiber 20 has a structure in which a core located at the center is covered with a surrounding clad, and only the core is made of a plastic scintillator which responds to radiation. Wavelength conversion fiber 22
Consists of a core and a cladding, and converts the wavelength of the incident light by the core.Here, it is used as a function that converts the light incident from the outside of the fiber into light that propagates in the fiber. . The wavelength conversion fiber used in the embodiment is of a type that converts light having a wavelength of 420 nm into light having a wavelength of 480 nm. If the wavelength to be converted matches the optimum sensitivity of the light receiving device located at the end, the detection sensitivity of the entire detector can be further improved. For example, when light is received by a photodiode, the detection efficiency is improved by converting the wavelength (from 420 to 480 nm).
【００１６】三層シート状構造のファイバ接合体２４
は、光学接着剤を用いて組み立てる。例えば、１層目と
なる多数の波長変換ファイバをテープケーブルのように
並べて接着し、その上に２層目の多数のシンチレーショ
ンファイバを並べて接着し、更にその上に３層目の多数
の波長変換ファイバを並べて接着するという方法で作製
できる。従って、各層間も完全とは言えないが、ある程
度の強度で接合され全体が保形されている。Fiber bonded body 24 having a three-layer sheet structure
Is assembled using an optical adhesive. For example, a large number of wavelength conversion fibers serving as a first layer are arranged and bonded like a tape cable, a large number of scintillation fibers of a second layer are arranged and bonded thereon, and further a large number of wavelength conversion fibers of a third layer are further provided thereon. It can be manufactured by a method of arranging and bonding fibers. Therefore, although the layers are not perfect, they are joined with a certain strength and the whole shape is maintained.
【００１７】図２に示すように、Ｕ型に折り返したファ
イバ接合体２４（シンチレーションファイバと波長変換
ファイバ）を、ファイバ両端を束ねて受光デバイスであ
る光電子増倍管３２に光学的に接続する。各ファイバを
Ｕ型に折り返す際には、全てのファイバをほぼ一定の曲
率で折り返えすことにより、折り返し面内でそれぞれの
ファイバ間隔をほぼ一定にでき、ファイバ間に大きな隙
間が生じない（不感ゾーンが生じない）ようにして感度
分布をほぼ全体にわたって均一にしている。As shown in FIG. 2, a fiber joint 24 (a scintillation fiber and a wavelength conversion fiber) folded in a U shape is optically connected to a photomultiplier tube 32 as a light receiving device by bundling both ends of the fiber. When each fiber is folded into a U-shape, all the fibers are folded at a substantially constant curvature, so that the spacing between the fibers can be made substantially constant in the folded surface, and a large gap does not occur between the fibers. Zone is not generated) to make the sensitivity distribution uniform over almost the entirety.
【００１８】図３は、本発明に係る検出器を用いた放射
線表面汚染モニタ装置全体の回路構成を示す説明図であ
る。光電子増倍管３２に高圧を印加する高圧電源３４
と、それぞれの光電子増倍管３２の出力を増幅する増幅
器３６、増幅信号を弁別するディスクリミネータ３８、
弁別波形を整形する波形整形回路４０、両方の波形整形
回路４０からの出力を受けてその同時性を検出する同時
計数回路４２と、計数計４４及び／又は指示計４６など
からなる。ここで、増幅器３６から同時計数回路４２ま
では回路基板上で組み立てられる。FIG. 3 is an explanatory diagram showing the circuit configuration of the entire radiation surface contamination monitoring device using the detector according to the present invention. High voltage power supply 34 for applying a high voltage to photomultiplier tube 32
An amplifier 36 for amplifying the output of each photomultiplier tube 32, a discriminator 38 for discriminating the amplified signal,
It comprises a waveform shaping circuit 40 for shaping a discrimination waveform, a coincidence circuit 42 for receiving the outputs from both waveform shaping circuits 40 and detecting their synchronism, a counter 44 and / or an indicator 46, and the like. Here, the components from the amplifier 36 to the coincidence circuit 42 are assembled on a circuit board.
【００１９】放射線表面汚染モニタ装置の外観の一例を
図４に示す。Ａは平面図、Ｂは正面図である。共通の底
板上に、検出面ケース５０と計測部ケース５２を設け、
該計測部ケース５２内に光電子増倍管と、増幅器から同
時計数回路までが組み込まれた回路基板とが収容され、
検出面ケース５０内に三層シート状構造のファイバ接合
体が組み込まれる。FIG. 4 shows an example of the appearance of the radiation surface contamination monitoring device. A is a plan view and B is a front view. A detection surface case 50 and a measurement unit case 52 are provided on a common bottom plate,
A photomultiplier tube and a circuit board including a circuit from an amplifier to a coincidence circuit are accommodated in the measurement unit case 52,
A fiber bonded body having a three-layer sheet structure is incorporated in the detection surface case 50.
【００２０】この放射線表面汚染モニタ装置は、身体汚
染モニタ（体表面モニタ）、物品搬送モニタ、あるいは
フットモニタなどとして有用である。身体あるいは物品
に付着した放射性物質から放出されるγ線がシンチレー
ションファイバ２０に入射すると、γ線による励起作用
によりシンチレーション光が発生する。その一部はシン
チレーションファイバ自身を光パイプ（ライトガイド）
として伝播する。シンチレーションファイバ２０内で発
生した光の大部分は外に漏れ出る。しかし、この漏れ光
は、近接する波長変換ファイバ２２に入射して内部分子
を励起する。内部分子が励起状態から基底状態に戻ると
きに、その分子固有の光を放出し、その光が波長変換フ
ァイバ２２自身を光パイプ（ライトガイド）として伝播
する。つまり、シンチレーションファイバ２０のみでは
漏れ光となり損失となる光が、波長変換ファイバ２２で
捉えられて、信号光として利用されることになる。The radiation surface contamination monitoring device is useful as a body contamination monitor (body surface monitor), an article transport monitor, a foot monitor, or the like. When γ-rays emitted from the radioactive substance attached to the body or the article enter the scintillation fiber 20, scintillation light is generated by the excitation action of the γ-rays. A part of the scintillation fiber itself is a light pipe (light guide).
Propagate as Most of the light generated in the scintillation fiber 20 leaks out. However, the leaked light enters the adjacent wavelength conversion fiber 22 to excite internal molecules. When the internal molecules return from the excited state to the ground state, the intrinsic molecules emit light, and the light propagates through the wavelength conversion fiber 22 itself as a light pipe (light guide). That is, light that becomes leakage light and is lost only with the scintillation fiber 20 is captured by the wavelength conversion fiber 22 and used as signal light.
【００２１】このようにしてシンチレーションファイバ
２０及び波長変換ファイバ２２の内部を伝播する光は、
両端に接続されている光電子増倍管３２に到達し、電気
信号に変換される。その電気信号は、増幅され、弁別さ
れ、整形されて同時計数回路４２に入力する。この同時
計数回路４２は、論理的なＡＮＤ回路を含んでおり、信
号が同時に入力するという条件が成立したときのみ検知
信号を出力し、この検知信号が計数される。放射線によ
って生じた発光（シンチレーション光のみならず、波長
変換された光）では、必ず光がファイバの両端に向かっ
て同時に伝播するため、両側の光電子増倍管３２の出力
に同時性が成り立つからである。これを利用することに
よって、回路における雑音の発生・侵入を排除し、検出
精度を高めている。The light propagating inside the scintillation fiber 20 and the wavelength conversion fiber 22 in this manner is:
The light reaches the photomultiplier tube 32 connected to both ends and is converted into an electric signal. The electric signal is amplified, discriminated, shaped, and input to the coincidence circuit 42. The coincidence counting circuit 42 includes a logical AND circuit, and outputs a detection signal only when a condition that signals are input simultaneously is satisfied, and the detection signal is counted. In light emission caused by radiation (not only scintillation light but also light whose wavelength has been converted), light always propagates toward both ends of the fiber at the same time, so that the outputs of the photomultiplier tubes 32 on both sides have synchronism. is there. By utilizing this, the occurrence and intrusion of noise in the circuit are eliminated, and the detection accuracy is increased.
【００２２】薄型放射線表面汚染検出器の構造の詳細例
を図５に示す。計測装置などを収容した計測部ケースと
共通の底板６０上に、鉄製枠体６２を載置し、該鉄製枠
体６２の内底部に鉛板６４を敷設する。鉄製枠体６２に
は、適当な間隔で荷重支えサポート６６を上向きに突設
する。鉛板６４は、例えば厚さ１mm程度であり、逆方向
（図５では下方向）からの放射線の入射を阻止し、バッ
クグラウンドを低減する機能を果たす。この鉛板６４の
上に、Ｕ型に折り返した三層シート状構造のファイバ接
合体２４（波長変換ファイバ２２−シンチレーションフ
ァイバ２０−波長変換ファイバ２２）を収容し、その上
面を検出面ケース（図示せず）で覆う。このように三層
シート状構造のファイバ接合体２４を囲むような構造と
して光漏れ防止を図っている。FIG. 5 shows a detailed example of the structure of the thin radiation surface contamination detector. An iron frame 62 is placed on a common bottom plate 60 with a measuring unit case accommodating a measuring device and the like, and a lead plate 64 is laid on the inner bottom of the iron frame 62. Load supporters 66 project upward from the iron frame 62 at appropriate intervals. The lead plate 64 has a thickness of, for example, about 1 mm, and has a function of preventing incidence of radiation from the opposite direction (downward in FIG. 5) and reducing the background. On this lead plate 64, a fiber bonded body 24 (wavelength conversion fiber 22, scintillation fiber 20, wavelength conversion fiber 22) having a three-layer sheet-like structure folded back into a U-shape is accommodated, and the upper surface thereof is a detection surface case (FIG. (Not shown). As described above, light leakage is prevented by a structure surrounding the fiber bonded body 24 having a three-layer sheet structure.
【００２３】試作品では、使用している各ファイバは直
径１mm程度であり、三層としたことで約３mm厚となる。
それに底板、鉄製枠体、鉛板などが加わるが、全体で１
０mm厚を実現できた。検出器の面積は、使用する光電子
増倍管、ファイバの直径などによって異なるが、試作品
では、直径３８mmの光電子増倍管を２本用いて、３００
mm×８００mmとした。同一条件でも、３００mm×２００
０mm程度までは大型化可能であると考えられる。In the prototype, each fiber used has a diameter of about 1 mm, and the thickness is about 3 mm due to the three layers.
In addition, a bottom plate, an iron frame, a lead plate, etc. are added.
A thickness of 0 mm was realized. The area of the detector varies depending on the photomultiplier used, the diameter of the fiber, and the like.
mm × 800 mm. 300mm × 200 even under the same conditions
It is considered that the size can be increased up to about 0 mm.
【００２４】なお、本発明に係る放射線表面汚染検出器
の検出対象は、前記のように、主としてγ線である。フ
ァイバが三層構造であると、上層の波長変換ファイバが
β線を遮蔽するためである。しかし、特に測定対象とし
ているわけではないが、高速中性子線には有感である。The object to be detected by the radiation surface contamination detector according to the present invention is mainly gamma rays as described above. This is because when the fiber has a three-layer structure, the wavelength conversion fiber in the upper layer shields β rays. However, although it is not particularly measured, it is sensitive to fast neutrons.
【００２５】以上、本発明の好ましい実施例について詳
述したが、かかる構成のみに限定されるものではない。
シンチレーションファイバと波長変換ファイバの配列の
仕方は自由である。効率的には上記のような三層構造が
最適であるが、互いに近接して配置されていればよい。
例えば二層構造としても、従来技術よりも感度はかなり
向上する。Although the preferred embodiment of the present invention has been described in detail above, the present invention is not limited to this configuration.
The arrangement of the scintillation fiber and the wavelength conversion fiber is arbitrary. The three-layer structure as described above is optimal for efficiency, but it is sufficient if they are arranged close to each other.
For example, even with a two-layer structure, the sensitivity is significantly improved over the prior art.
【００２６】[0026]
【発明の効果】本発明は上記のように、多数のシンチレ
ーションファイバと波長変換ファイバを近接配置した構
造の放射線表面汚染検出器であるので、検出感度及びエ
ネルギーレスポンスが良好となり、大面積化に適し、薄
型化できる効果が生じる。As described above, the present invention is a radiation surface contamination detector having a structure in which a large number of scintillation fibers and wavelength conversion fibers are arranged close to each other, so that the detection sensitivity and the energy response are good and suitable for a large area. Thus, the effect of reducing the thickness is obtained.
【００２７】また本発明で、各シンチレーションファイ
バと各波長変換ファイバを、ほぼ一定の曲率でほぼ同一
平面内で折り返えす構造とすると、シンチレーションフ
ァイバをＵ型に折り返す際にファイバ同士の間隔を一定
にでき、大きな隙間が生じず（従って不感ゾーンが生じ
ず）、検出感度分布を検出器全面にわたってほぼ一様に
できる効果が得られる。In the present invention, when each scintillation fiber and each wavelength conversion fiber are folded back in a substantially same plane with a substantially constant curvature, when the scintillation fiber is folded back into a U-shape, the spacing between the fibers is constant. Thus, there is obtained an effect that the detection sensitivity distribution can be made substantially uniform over the entire surface of the detector without generating a large gap (therefore, no dead zone is generated).
【図１】本発明に係る薄型放射線表面汚染検出器におけ
るファイバ配列状態の一例を示す説明図。FIG. 1 is an explanatory view showing an example of a fiber arrangement state in a thin radiation surface contamination detector according to the present invention.
【図２】ファイバのＵ型折り返し構造を示す説明図。FIG. 2 is an explanatory view showing a U-shaped folded structure of a fiber.
【図３】放射線表面汚染モニタ装置の回路構成を示すブ
ロック図。FIG. 3 is a block diagram showing a circuit configuration of the radiation surface contamination monitoring device.
【図４】放射線表面汚染モニタ装置の一例を示す外観説
明図。FIG. 4 is an external view illustrating an example of a radiation surface contamination monitoring device.
【図５】本発明に係る放射線表面汚染検出器の構造の一
例を示す構造説明図。FIG. 5 is a structural explanatory view showing an example of the structure of a radiation surface contamination detector according to the present invention.
【図６】シンチレーションファイバの構造と発光の伝播
状態の説明図。FIG. 6 is an explanatory diagram of a structure of a scintillation fiber and a propagation state of light emission.
２０ シンチレーションファイバ ２２ 波長変換ファイバ ２４ ファイバ接合体 ３２ 光電子増倍管 Reference Signs List 20 scintillation fiber 22 wavelength conversion fiber 24 fiber joint 32 photomultiplier tube
Claims (5)
に配列し、Ｕ型に折り返しファイバ両端を束ねて受光デ
バイスに接続することで、該受光デバイスを片側に配置
した放射線検出器において、 多数のシンチレーションファイバに近接して多数の波長
変換ファイバを平行に配列し、それら波長変換ファイバ
もＵ型に折り返しファイバ両端を束ねて受光デバイスに
接続したことを特徴とする薄型放射線表面汚染検出器。1. A radiation detector in which a large number of scintillation fibers are arranged in parallel, folded in a U-shape, and both ends of the fibers are bundled and connected to a light receiving device. A thin radiation surface contamination detector characterized in that a number of wavelength conversion fibers are arranged in parallel in close proximity, and these wavelength conversion fibers are also folded back into a U-shape and both ends are bundled and connected to a light receiving device.
配列した層の上下両面に、多数の波長変換ファイバを近
接配列した層を配置して全体を三層構造とした請求項１
記載の薄型放射線表面汚染検出器。2. A three-layer structure in which a plurality of wavelength conversion fibers are arranged in close proximity on both upper and lower surfaces of a layer in which a large number of scintillation fibers are arranged in close proximity.
The thin radiation surface contamination detector as described.
換ファイバが、ほぼ一定の曲率でほぼ同一平面内で折り
返えされている請求項１又は２記載の薄型放射線表面汚
染検出器。3. The thin radiation surface contamination detector according to claim 1, wherein each of the scintillation fibers and each of the wavelength conversion fibers are bent at a substantially constant curvature in substantially the same plane.
の波長変換ファイバが、光学接着剤により密着接合され
てシート状のファイバ接合体に成形されている請求項３
記載の薄型放射線表面汚染検出器。4. A plurality of scintillation fibers and a plurality of wavelength conversion fibers are tightly bonded by an optical adhesive to form a sheet-like fiber bonded body.
The thin radiation surface contamination detector as described.
に鉛板を敷設し、その上に、Ｕ型に折り返したシート状
のファイバ接合体を収容し、上面を検出面ケースで覆っ
た請求項４記載の薄型放射線表面汚染検出器。5. A frame is placed on a bottom plate, a lead plate is laid on the inner bottom of the frame, and a U-shaped sheet-like fiber joined body is accommodated thereon, and the upper surface is detected. The thin radiation surface contamination detector according to claim 4, which is covered with a surface case.
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| JP2000132100A JP3463018B2 (en) | 2000-05-01 | 2000-05-01 | Thin radiation surface contamination detector |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2000132100A JP3463018B2 (en) | 2000-05-01 | 2000-05-01 | Thin radiation surface contamination detector |
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| JP3463018B2 JP3463018B2 (en) | 2003-11-05 |
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| WO2006111323A2 (en) | 2005-04-16 | 2006-10-26 | Rados Technology Gmbh | Low-weight flat detector for detecting radiation of contaminated object particles |
| JP2007114145A (en) * | 2005-10-24 | 2007-05-10 | Mitsubishi Electric Corp | Form variable radiation detector |
| JP2007114067A (en) * | 2005-10-20 | 2007-05-10 | Wired Japan:Kk | Radiation detection system and radiation detection method |
| JP2010043971A (en) * | 2008-08-13 | 2010-02-25 | Toshiba Corp | Radiation detector |
| WO2013186798A2 (en) * | 2012-06-12 | 2013-12-19 | Infn Istituto Nationale Di Fisica Nucleare | Detector based on scintillating optical fibers for charged particles tracking with application in the realization of a residual range detector employing a read-out channels reduction and compression method |
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| WO2013186798A3 (en) * | 2012-06-12 | 2014-05-08 | Infn Istituto Nationale Di Fisica Nucleare | Detector based on scintillating optical fibers for charged particles tracking with application in the realization of a residual range detector employing a read-out channels reduction and compression method |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3463018B2 (en) | 2003-11-05 |
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