JPH0799395B2 - Radiation applied measurement device - Google Patents
Radiation applied measurement deviceInfo
- Publication number
- JPH0799395B2 JPH0799395B2 JP63152781A JP15278188A JPH0799395B2 JP H0799395 B2 JPH0799395 B2 JP H0799395B2 JP 63152781 A JP63152781 A JP 63152781A JP 15278188 A JP15278188 A JP 15278188A JP H0799395 B2 JPH0799395 B2 JP H0799395B2
- Authority
- JP
- Japan
- Prior art keywords
- radiation
- detector
- radiation source
- sensitivity
- light receiving
- 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.)
- Expired - Lifetime
Links
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- Length-Measuring Devices Using Wave Or Particle Radiation (AREA)
- Analysing Materials By The Use Of Radiation (AREA)
- Measurement Of Radiation (AREA)
- Light Receiving Elements (AREA)
Description
【発明の詳細な説明】 ＜産業上の利用分野＞ 本発明は放射線を用いて紙，プラスチック，ゴムなどの
物理量（秤量，水分等）を測定する放射線応用測定装置
に関する。DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a radiation applied measuring apparatus for measuring a physical quantity (weighing amount, water content, etc.) of paper, plastic, rubber or the like using radiation.
＜従来の技術＞ 放射線（例えばβ線）が物質層を通過すると，電離作用
や励起作用等によって次第にエネルギーを失って減衰
し，更にこの様な非弾性散乱を多数回受けて進行方向が
変化する。従って測定体の物理量（例えば厚さ）が増す
に伴い透過するβ線の数は減少する。この様な原理を応
用し，シート状の種々の物質の物理量を測定する装置が
知られている。<Prior Art> When radiation (eg, β-rays) passes through a material layer, it gradually loses energy due to ionization and excitation, and is attenuated, and further undergoes such inelastic scattering and changes its traveling direction. . Therefore, as the physical quantity (for example, thickness) of the measurement object increases, the number of β rays transmitted decreases. By applying such a principle, a device for measuring physical quantities of various sheet-like substances is known.
この様な放射線応用測定装置は第４図に示す様に放射線
源１と放射線検出器（以下，単に検出器という）２を対
向させて配置し，その間に被測定体３を挟んで測定する
ように構成されている。この放射線源は正面が最も強く
正面から遠ざかる程弱くなる。従って，放射線源１が検
出器２に対してX,Y方向またはＺ方向に移動した場合に
は，検出器２に入射する放射線量が変化して測定誤差を
生じるという問題がある。In such a radiation applied measuring device, as shown in FIG. 4, a radiation source 1 and a radiation detector (hereinafter, simply referred to as “detector”) 2 are arranged so as to face each other, and an object to be measured 3 is sandwiched therebetween for measurement. Is configured. This radiation source is strongest in the front and weakens as it moves away from the front. Therefore, when the radiation source 1 moves in the X, Y or Z directions with respect to the detector 2, there is a problem that the amount of radiation incident on the detector 2 changes and a measurement error occurs.
従来，この種の測定誤差を除去する装置として第５図
（イ），（ロ），（ハ）に示すようなものが提案されて
いる。即ち，検出器の放射線を受ける部分2a（以下，単
に受光部という）に放射線の照射方向（Ｘ方向）に対し
て直角に吸収板６を配置して，放射線源１と受光部2aと
の位置関係の変化に起因する測定誤差を軽減したもので
ある。第５図（イ）は放射線源１と受光部2aおよび吸収
板６の関係を平面図で示すもので，吸収板６は検出器の
受光部の中央部にＸ方向に対して直角に，放射線源は受
光部の中央に配置されている。吸収板６は長さｌが受光
部の直径よりも長く，幅Ｗが放射線源より広く受光窓の
直径より小さいアルミニゥム板からなり，受光部2aの前
面の中央部に取付けられて，放射線源１の放射線ビーム
の最も強い部分の一部を遮って受光部2aに入射する放射
線量を減少させている。なお，検出器としては一般に電
離箱が用いられ，また，放射線源１は通常安全対策とし
て金属箔等で包まれており，更に線源箱の出口が薄い金
属板等で覆われているので，線源１から放射された放射
線は直進しにくく散乱線となる。このため，放射線ビー
ムの強さは線源１の正面が最も強く正面から遠ざかる程
弱くなる。Conventionally, as shown in FIGS. 5 (a), 5 (b) and 5 (c), a device for removing this kind of measurement error has been proposed. That is, the absorption plate 6 is arranged at a portion 2a of the detector that receives radiation (hereinafter, simply referred to as a light receiving portion) at a right angle with respect to the radiation irradiation direction (X direction), and the positions of the radiation source 1 and the light receiving portion 2a. The measurement error caused by the change in the relationship is reduced. FIG. 5 (a) is a plan view showing the relationship between the radiation source 1, the light receiving portion 2a and the absorption plate 6, which is perpendicular to the X direction at the center of the light receiving portion of the detector. The source is located in the center of the light receiver. The absorption plate 6 is made of an aluminum plate having a length 1 longer than the diameter of the light receiving portion and a width W wider than the radiation source and smaller than the diameter of the light receiving window. That is, a part of the strongest part of the radiation beam is blocked to reduce the amount of radiation incident on the light receiving part 2a. An ionization chamber is generally used as the detector, and the radiation source 1 is usually wrapped with a metal foil or the like as a safety measure, and the outlet of the radiation source box is covered with a thin metal plate or the like. The radiation emitted from the radiation source 1 is hard to go straight and becomes scattered rays. Therefore, the intensity of the radiation beam is strongest at the front of the radiation source 1 and becomes weaker as it goes away from the front.
第５図（ロ）は検出器２がＸ方向（向かって左側）にX1
ずれた状態を示す側面図で,Rは放射線の等価線量を示し
ている。この様なずれが発生した場合，向かって左側は
放射線源から遠ざかるので出力は弱くなるが，向かって
右側は吸収板６に遮られていた放射線の最も強い部分が
受光面を照射する様になるので出力は強くなる。従って
受光部が受ける放射線の総量は変化せず，ずれによる出
力変動は発生しない。In Fig. 5 (b), the detector 2 is X 1 in the X direction (to the left).
In the side view showing the shifted state, R indicates the equivalent dose of radiation. When such a shift occurs, the left side is away from the radiation source, so the output is weak, but the right side is such that the strongest portion of the radiation blocked by the absorption plate 6 irradiates the light receiving surface. Therefore, the output becomes stronger. Therefore, the total amount of radiation received by the light receiving unit does not change, and output fluctuations due to deviation do not occur.
第５図（ハ）は検出器がＺ方向（図では上方向）にz1ず
れた状態を示す側面図で，この例では受光面が放射線源
に近付くので吸収板６で覆われていない部分は出力が増
加する様に作用し，同時に放射線の強い部分がより広く
放射線６で覆われることになるので放射線の総量は変化
せず，ずれによる出力変動は発生しない。FIG. 5C is a side view showing a state where the detector is displaced by z 1 in the Z direction (upward direction in the figure). In this example, the light receiving surface is close to the radiation source, and therefore the portion not covered by the absorption plate 6 Acts so as to increase the output, and at the same time, since the strong radiation portion is more widely covered with the radiation 6, the total amount of radiation does not change, and the output variation due to the deviation does not occur.
上記構成によれば，放射線源と検出器の関係がX,Z方向
に移動しても放射線量の総量をほぼ同一にすることが可
能である。なお,Y方向のずれに対しては図示した吸収板
では対応できない。しかし現実には吸収板の形状を工夫
することにより対処している。According to the above configuration, even if the relationship between the radiation source and the detector moves in the X and Z directions, the total amount of radiation can be made almost the same. It should be noted that the illustrated absorbing plate cannot deal with the deviation in the Y direction. However, in reality, it is dealt with by devising the shape of the absorbing plate.
＜発明が解決しようとする課題＞ しかしながら，上記従来の放射線応用測定装置において
は，放射線源は吸収板６の幅Ｗより小さくする必要があ
る。従来の装置においては例えば放射線源の径20mm程度
に対し検出器側の直径は80mm程度とされており，検出器
としては電離箱等が使用されている。この為測定装置の
小形化が難しいという課題があった。<Problems to be Solved by the Invention> However, in the above-described conventional radiation applied measurement apparatus, the radiation source needs to be smaller than the width W of the absorption plate 6. In the conventional device, for example, the diameter of the radiation source is about 20 mm and the diameter on the detector side is about 80 mm, and an ion chamber or the like is used as the detector. Therefore, there is a problem that it is difficult to downsize the measuring device.
本発明は上記従来技術の課題に鑑みて成されたもので，
放射線を用いてその透過量を測定し膜厚や秤量等の物理
量を求める装置において，検出器として半導体検出器を
用い，その放射線感度に勾配をもたせることにより測定
装置の小形化および放射線源と受光器のずれに基因する
誤差防止をはかった放射線応用測定装置を実現すること
を目的とする。The present invention has been made in view of the above problems of the prior art,
In a device that measures the amount of transmission using radiation to determine physical quantities such as film thickness and weighing, a semiconductor detector is used as the detector, and the radiation sensitivity is graded by using a semiconductor detector, and the radiation source and the light receiving It is an object of the present invention to realize a radiation applied measurement device that prevents errors due to instrument misalignment.
＜課題を解決するための手段＞ 上記課題を解決するための本発明の構成は，放射線源か
ら放射され被測定体を透過してくる放射線を放射線検出
器により検出し，前記被測定体の物理量の測定を行う放
射線応用測定装置において，前記放射線検出器は半導体
からなり，中心から外側に向かって放射線感度が高くな
るように感度勾配を設けたことを特徴とするものであ
る。<Means for Solving the Problems> According to the configuration of the present invention for solving the above problems, radiation emitted from a radiation source and transmitted through an object to be measured is detected by a radiation detector, and a physical quantity of the object to be measured is detected. In the radiation applied measuring apparatus for performing the above measurement, the radiation detector is made of a semiconductor, and a sensitivity gradient is provided so that the radiation sensitivity increases from the center toward the outside.
＜実施例＞ 第１図（イ）は本発明の一実施例を示す放射線検出器の
要部断面図である。図において10は例えばCdTeからなる
ｐ型半導体ウエハであり，このウエハの一方の面にAlを
拡散してｎ型層11が形成され,n層側にAl電極12が，他方
の側にAuオーミック電極13が形成されている。<Embodiment> FIG. 1 (A) is a sectional view of a main part of a radiation detector showing an embodiment of the present invention. In the figure, reference numeral 10 denotes a p-type semiconductor wafer made of, for example, CdTe. An n-type layer 11 is formed by diffusing Al on one surface of the wafer, an Al electrode 12 is provided on the n-layer side, and an Au ohmic contact is provided on the other side. The electrode 13 is formed.
ところでこの検出器の放射線感度は第１図（ロ）に示す
ように中央Ａ部が最も弱く外周のB,C方向に向かって感
度が強くなるように形成されている。なお，この様な感
度勾配を持つ検出器は例えばAlを拡散させる際に，ウエ
ハ内に温度分布を持たせて熱処理を行い,pn接合の深さ
を変化させたり，受光部上に内側にいくほど厚くなる様
な遮蔽膜を形成することにより製作可能である。By the way, as shown in FIG. 1B, the radiation sensitivity of this detector is formed such that the central portion A is weakest and the sensitivity is increased toward the outer peripheral B and C directions. A detector with such a sensitivity gradient, for example, when diffusing Al, heat-treats it with a temperature distribution inside the wafer to change the depth of the pn junction or to move it inside the photodetector. It can be manufactured by forming a shielding film that becomes thicker.
第２図は放射線源の位置と放射線強度の関係を示すもの
で，線源の正面ａの位置の強度が最も強く，正面から離
れるに従って強度が弱くなっている状態を示している。FIG. 2 shows the relationship between the position of the radiation source and the radiation intensity, and shows the state in which the intensity at the position of the front face a of the radiation source is the strongest and the intensity becomes weaker as it moves away from the front face.
第３図は線源と検出器を対向して固定した場合の強度お
よび感度の関係を模式的に示すもので，（イ）図はずれ
のない状態を，（ロ）図は検出器の位置が中心からＳだ
けずれA,B,Cの位置がA-,B-,C-の位置にずれた状態を示
している。このように位置ずれが生じた場合，ずれ量Ｓ
に対応して左側のC-を含む部分は感度がなくなるが，放
射線強度の一番強いａの部分に放射線感度の高い部分が
近付き，右側のC-の部分は放射線強度の高い側に近付く
ので全体としての受光感度は互いに相殺し出力には変化
がない。Fig. 3 schematically shows the relationship between the intensity and sensitivity when the radiation source and the detector are fixed facing each other. Fig. 3 (a) shows the state without deviation, and Fig. 3 (b) shows the position of the detector. It shows a state in which the positions of A, B, and C deviated from the center by S deviate to the positions of A − , B − , and C − . If such a position shift occurs, the shift amount S
Corresponding to the left side of the C - but part sensitivity is eliminated including, the strongest a portion of the radiation intensity approaches a high portion of radiation sensitivity, right C - because the portion of the approach with high radiation intensity side The light receiving sensitivities as a whole cancel each other out and the output remains unchanged.
なお，出力誤差の調整は検出器と放射線源の距離を変化
させることにより可能である。The output error can be adjusted by changing the distance between the detector and the radiation source.
また，本実施例では放射線をβ線としたがβ線に限るこ
となく，同様の効果を有する他の放射線であってもよ
い。Further, in the present embodiment, the radiation is β rays, but the radiation is not limited to β rays and may be other radiation having the same effect.
また，半導体ウエハはCdTeに限ることなく放射線感度を
有するものであれば例えばSi,GaAs等であってもよい。Further, the semiconductor wafer is not limited to CdTe, and may be Si, GaAs or the like as long as it has radiation sensitivity.
＜発明の効果＞ 以上，実施例とともに具体的に説明したように本発明に
よれば，検出器として半導体検出器を用い，中心から外
周に向かって感度が高くなるように感度勾配を設けたの
で，平板状の吸収板を検出器側に配置する従来例に比較
して小形化が可能である。また，吸収板が不要となるの
で構成の簡単な放射線応用測定装置を実現することが出
来る。<Effects of the Invention> According to the present invention as specifically described above with the embodiments, the semiconductor detector is used as the detector, and the sensitivity gradient is provided so that the sensitivity increases from the center toward the outer periphery. The size can be reduced compared to the conventional example in which a flat absorption plate is placed on the detector side. Further, since the absorption plate is not required, it is possible to realize a radiation applied measuring device with a simple structure.
第１図は本発明の放射線検出器の一実施例を示す要部断
面図，第２図は放射線源の位置と強度の関係を示す図，
第３図は検出器と放射線源の位置関係を示す図，第４
図，第５図は従来例を示す構成説明図である。 10……ｐ型半導体ウエハ,11……ｎ型層,12……Al電極,1
3……Auオーミック電極。FIG. 1 is a sectional view of a main part showing an embodiment of the radiation detector of the present invention, and FIG. 2 is a view showing the relationship between the position and intensity of a radiation source,
FIG. 3 is a diagram showing the positional relationship between the detector and the radiation source, and FIG.
FIG. 5 and FIG. 5 are configuration explanatory views showing a conventional example. 10 …… p-type semiconductor wafer, 11 …… n-type layer, 12 …… Al electrode, 1
3 ... Au ohmic electrode.
Claims (1)
くる放射線を放射線検出器により検出し，前記被測定体
の物理量の測定を行う放射線応用測定装置において，前
記放射線検出器は半導体からなり，中心から外側に向か
って放射線感度が高くなるように感度勾配を設けたこと
を特徴とする放射線応用測定装置。1. A radiation applied measuring device for detecting radiation emitted from a radiation source and passing through an object to be measured by a radiation detector to measure a physical quantity of the object to be measured, wherein the radiation detector is made of a semiconductor. The radiation applied measuring device is characterized in that a sensitivity gradient is provided so that the radiation sensitivity increases from the center toward the outside.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63152781A JPH0799395B2 (en) | 1988-06-21 | 1988-06-21 | Radiation applied measurement device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63152781A JPH0799395B2 (en) | 1988-06-21 | 1988-06-21 | Radiation applied measurement device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH026731A JPH026731A (en) | 1990-01-10 |
| JPH0799395B2 true JPH0799395B2 (en) | 1995-10-25 |
Family
ID=15548009
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP63152781A Expired - Lifetime JPH0799395B2 (en) | 1988-06-21 | 1988-06-21 | Radiation applied measurement device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0799395B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2678716B2 (en) * | 1992-12-24 | 1997-11-17 | 花王株式会社 | Method for producing pearlescent agent dispersion |
-
1988
- 1988-06-21 JP JP63152781A patent/JPH0799395B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH026731A (en) | 1990-01-10 |
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