JP2002341036A - Radiation detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radiation detector allowing a scintillator with wide area to effectively function and having uniform and high detection efficiency regardless of incident position of beta ray with a low background count by gamma ray. SOLUTION: This radiation detector comprises the thin plate-like scintillator 1 arranged on a measuring surface, a light guide plate 2 laid along and optically connected to the reverse side of the scintillator 1 to guide light, a condenser part 3 optically connected to the side surface of the scintillator 1, a photoelectric conversion element 4 optically connected to the condenser part 3, and a signal processing circuit 5 connected to the photoelectric conversion element 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation detector used in a nuclear facility or the like, and more particularly to a radiation detector using a scintillator as a background for reducing gamma ray counting for measurement.

[0002]

2. Description of the Related Art Conventionally, a nuclear facility such as a nuclear power plant is provided with a large-area scintillator for the purpose of detecting contamination of a person who has entered the facility and has performed some work, used tools and clothes. Uses a radiation detector. FIG. 13 shows a configuration example of this type of radiation detection apparatus.

[0003] The radiation detecting apparatus shown in FIG. 13 converts scintillation light generated in a flat scintillator 22 into light.
After irregularly reflecting and condensing the light on the wall surface of the detector container 24 coated with the light reflecting paint 23, the light is converted into an electric signal by a plurality of photoelectric conversion elements 25 having a relatively large photoelectric surface and measured.

At the time of measurement, in order to improve the S / N ratio and increase the radiation detection sensitivity, a coincidence circuit performs coincidence measurement on output signals from a plurality of photoelectric conversion elements 25. Further, extraneous light is blocked by the light shielding film 26 so that only radiation enters the flat scintillator 22.

Further, in order to reduce the influence of gamma rays which hinder counting as a background when measuring a target beta ray, the scintillator 22 is made as thin as possible. Then, a scintillator having an area smaller than that of the scintillator 22 is additionally attached near the scintillator 22 so that the detection efficiency for beta rays does not differ depending on the incident position on the scintillator 22.

[0006]

In the conventional radiation detecting apparatus, when the scintillation light is to be condensed by the condensing portion, the scintillation light leaks from the curved portion because the scintillator cannot maintain a flat plate shape. I got out,
Light collection efficiency has decreased. In addition, since the scintillation light is condensed by a condensing portion optically connected to the side surface of the scintillator, it is difficult to improve the detection efficiency even if a scintillator is added in the vicinity of the scintillator.

Therefore, the present invention provides a radiation detecting apparatus which can effectively operate a scintillator having a large area, has a low background count by gamma rays, and has a uniform and high detection efficiency regardless of the incidence position of beta rays. The purpose is to:

[0008]

According to a first aspect of the present invention, there is provided a radiation detecting apparatus comprising: a thin plate-shaped scintillator disposed on a measurement surface; and a scintillator optically connected to a back surface of the scintillator. A light guide plate for guiding light, a light condensing part optically connected to a side surface of the scintillator, a photoelectric conversion element optically connected to the light condensing part, and a signal processing circuit connected to the photoelectric conversion element And a configuration including:

In the radiation detecting apparatus according to the present invention, rigidity can be increased by physically supporting the thin scintillator with the light guide plate. Therefore, light loss at the connection surface between the light collector and the scintillator is reduced, and light can be collected by the light collector from the side surface of the scintillator. Further, since the connecting surface between the scintillator and the light guide plate is very small, it is possible to use an adhesive having a stronger adhesive force than the optical adhesive, and the structure becomes robust. Therefore, it is possible to collect sufficient light from a scintillator thinned so that the background count by gamma rays is reduced, and to realize high detection efficiency for beta rays.

In a second aspect of the present invention, in the first aspect, the light guide plate covers the entire back surface of the scintillator, and the light collecting portion is optically connected to the side surface of the light guide plate.
In the radiation detection device according to the present invention, not only the side surface of the scintillator, but also the light leaked from the plane of the scintillator, the light transmitted through the light guide plate and reaching the side surface of the light guide plate is also condensed. High light collecting ability can be obtained.

According to a third aspect of the present invention, in the second aspect of the present invention, the scintillator and the light guide plate are optically connected over the entire surface, and the back surface of the light guide plate has a mirror surface for totally reflecting light.

In the radiation detecting apparatus according to the present invention, the light from the scintillator is totally reflected between the front surface of the scintillator and the back surface of the light guide plate and reaches the light collecting portion, so that a high light collecting ability is obtained. In addition, mechanical damage and noise due to the scintillator rubbing against the light guide plate are less likely to occur, and the mechanical robustness is improved.

According to a fourth aspect of the present invention, in the second aspect, the scintillator and the light guide plate are partially optically connected, and the back surface of the light guide plate has a rough surface that diffusely reflects light. Even if light from the scintillator enters the light guide plate, light incident at an angle larger than the critical angle of total reflection at the connection surface exits the light guide plate from the back surface. Has a rough surface finish, the light from the light guide plate undergoes irregular reflection on the back surface, and a part of the light reaches the side surface of the light guide plate, and a high light-collecting ability is obtained.

According to a fifth aspect of the present invention, in the second aspect of the present invention, the scintillator comprises a main scintillator covering the entire radiation detecting surface, and a sub-scintillator having a smaller area optically connected to the main scintillator, The sub-scintillator is arranged around the main scintillator.

In the radiation detecting apparatus according to the present invention, since the thickness of the entire scintillator around the main scintillator is increased, the detection efficiency for beta rays is increased. The light from the sub-scintillator also reaches the light-collecting portion through the light guide plate similarly to the light from the main scintillator, and is collected. Therefore, it becomes possible to collect more light from the scintillator thinned so that the background count by gamma rays is reduced, and higher detection efficiency for beta rays is realized. In addition, uniform and high detection efficiency can be obtained regardless of the incidence position of the beta ray.

According to a sixth aspect of the present invention, in the second aspect of the present invention, the light condensing portion is a light guide of a wavelength conversion type, and the scintillator is constituted by a plurality of small area scintillators, and is provided at a central portion of the radiation detecting surface. The emission wavelength of the small-area scintillator is set to a wavelength slightly apart from the absorption wavelength of the light guide, and the emission wavelength of the small-area scintillator provided on the periphery of the radiation detection surface is adapted to the absorption wavelength of the light guide. The wavelength is set to the set value.

In the radiation detecting apparatus according to the present invention, light from a plurality of small area scintillators having different emission wavelengths can be guided to the wavelength conversion type light guide through the light guide plate without waste. The output light emission of the wavelength conversion type light guide is
When the light from the scintillator whose light emission wavelength matches the light absorption peak of the wavelength conversion light guide is absorbed, the light emission wavelength does not match the light absorption peak of the wavelength conversion light guide. Since the light from the scintillator is larger than when the light is absorbed, the detection efficiency of beta rays is higher when the light is incident on the former small area scintillator than when the light is incident on the latter small area scintillator. Therefore, more light can be collected from a scintillator thinned so that the background count by gamma rays is reduced, and higher detection efficiency for beta rays can be obtained. In addition, uniform and high detection efficiency can be obtained regardless of the incidence position of the beta ray.

According to a seventh aspect of the present invention, in the second aspect of the present invention, the condensing section is a light guide of a wavelength conversion type, and the scintillator is constituted by a plurality of small area scintillators, and is provided at a central portion of the radiation detecting surface. The thickness of the small area scintillator is set to be smaller than the thickness of the small area scintillator provided on a peripheral portion of the radiation detection surface.

In the radiation detecting apparatus according to the present invention, light from a plurality of small area scintillators having different thicknesses can be guided to the wavelength conversion type light guide without waste through the light guide plate. Since the light emission of the thick small area scintillator is larger than the light emission of the thin small area scintillator, the detection efficiency of beta rays is better when the light is incident on the thick small area scintillator.
It becomes larger than when it is incident on a thin small area scintillator. Therefore, more light can be collected from a scintillator thinned so that the background count by gamma rays is reduced, and higher detection efficiency for beta rays can be obtained. In addition, uniform and high detection efficiency can be obtained regardless of the location of the beta ray incidence.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A radiation detecting apparatus according to a first embodiment of the present invention will be described with reference to FIG. That is, a thin plate-shaped scintillator 1 which is placed on a radiation detection surface opposite to a detection target and cannot stand alone by itself can be formed into a light guide plate 2 which is transparent to scintillation light from the scintillator 1. Optically connected to The connection uses, for example, an adhesive, and the adhesive surface has a very small area that allows minimum fixing. The light guide plate 2 uses, for example, an acrylic plate having a thickness of about 5 mm.

The light collector 3 is optically connected to the side surface of the scintillator 1. The connection is made by using, for example, an optical adhesive or by providing a groove in the wavelength conversion type light guide and inserting the scintillator 1 therein. The photoelectric conversion element 4 is optically connected to the light collecting section 3. As a connection method, for example, optical grease is used.

The minute electric signal from the photoelectric conversion element 4 is
The signal is input to a signal processing circuit 5 that performs amplification, frequency band filtering, and pulse height discrimination. The connection between the two is made, for example, by a wire or cable. The output of the signal processing circuit 5 is input to the coincidence circuit 6. The output of the coincidence circuit 6 is input to an interface circuit 7 for generating an alarm and displaying a count value.

Further, the scintillator 1, the light guide plate 2, the light condensing part 3, and the photoelectric conversion element 4 function as a detector container 8 which blocks light from the outside and has a measurement surface through which beta rays pass, or an equivalent function. Cover with shield.

In the radiation detecting apparatus according to the first embodiment having such a structure, a thin scintillator 1 which cannot stand alone and is not able to be a plane by itself is physically supported by a light guide plate 2 to form a flat plate. Light loss from the curved surface is reduced, and light can be collected from the side surface of the scintillator 1 by the light collector 3. Further, since the connecting surface between the scintillator 1 and the light guide plate 2 is very small, it is possible to use an adhesive having a stronger adhesive force than the optical adhesive, and the structure becomes robust. Therefore, it is possible to collect sufficient light from a scintillator thinned so that the background count by gamma rays is reduced, and to realize high detection efficiency for beta rays.

FIG. 2 shows a configuration of a main part of a radiation detecting apparatus according to a second embodiment of the present invention. That is, in the radiation detecting apparatus according to the first embodiment, the light guide plate 2 covers the entire back surface of the scintillator 1, and the light collector 3 is optically connected across both the side surfaces of the scintillator 1 and the light guide plate 2. It was done. Other configurations are the same as those of the first embodiment.

In the radiation detecting apparatus according to the second embodiment, not only the side surface of the scintillator 1 but also the light leaked from the plane of the scintillator 1 is transmitted through the light guide plate 2 to the side surface of the light guide plate 2. By condensing the reached light at the same time, it is possible to obtain a higher light condensing ability than the radiation detecting apparatus of the above-described first embodiment.

In the second embodiment, the back surface 13 of the light guide plate 2 may be roughened so as to diffusely reflect the light.
Even if light from the scintillator 1 enters the light guide plate 2, light incident at an angle larger than the critical angle of total reflection on the attachment surface 11 exits the light guide plate 2 from the back surface 13. When the back surface 13 of the light plate 2 is roughened, the light of the light guide plate 2 diffusely reflects on the back surface 13, and a part of the light reaches the side surface of the light guide plate 2.

A radiation detecting apparatus according to a third embodiment of the present invention will be described with reference to FIG. That is, an optical adhesive or the like is applied to the entire surface 2 of the bonding surface 11 between the scintillator and the light guide plate, and the entire surface of the scintillator 1 is optically connected to the light guide plate 2. Other configurations are the same as those of the above-described second embodiment.

In the radiation detecting apparatus according to the third embodiment, the light from the scintillator 1 is reflected between the front surface 12 of the scintillator 1 and the back surface 13 of the light guide plate 2 and the light condensing portion 3
Therefore, there is no light loss in the gap between the scintillator 1 and the light guide plate 3 which occurs in the case of bonding by a very small area. Therefore, a higher light-collecting ability than the radiation detection device according to the second embodiment can be expected. In addition, mechanical damage and noise are less likely to occur due to the scintillator 1 rubbing against the light guide plate 2, and the mechanical robustness is improved.

In the third embodiment, it is more preferable that the back surface 13 of the light guide plate 2 is mirror-finished. That is, in this case, the light from the scintillator 1 is totally reflected between the front surface 12 of the scintillator 1 and the back surface 13 of the light guide plate 2 and reaches the light collecting section 3, so that a higher light collecting ability can be obtained.

A radiation detecting apparatus according to a fourth embodiment of the present invention will be described with reference to FIG. That is, a sub-scintillator 1a having an area smaller than that of the main scintillator 1 is optically connected to the surface 12 of the main scintillator 1. The position of the sub-scintillator 1a is set at the periphery of the main scintillator 1. The back surface 13 of the light guide plate 2 is
When the entire surface of the light guide plate 2 and the light guide plate 2 are optically connected to the main scintillator 1, a mirror surface finish that totally reflects the light is used.

In the radiation detecting apparatus according to the fourth embodiment, since the thickness of the entire scintillator around the main scintillator 1 increases, the detection efficiency for beta rays increases. The light from the sub scintillator 1a also reaches the light collector 3 through the light guide plate 2 and is collected like the light from the main scintillator 1. Therefore, it is possible to collect more light from a scintillator thinned so that the background count by gamma rays is reduced,
Higher detection efficiency for beta rays is achieved. In addition, uniform and high detection efficiency can be obtained regardless of the incidence position of the beta ray.

A radiation detecting apparatus according to a fifth embodiment of the present invention will be described with reference to FIG. That is, the main scintillator 1 and the sub-scintillator 1a having a smaller area than the main scintillator 1 are optically connected to the bonding surface 11 of the light guide plate 2. The position of the sub-scintillator 1a is set at the periphery of the main scintillator 1. The back surface 13 of the light guide plate 2 has a mirror finish that totally reflects when the entire surface of the sub-scintillator 1a and the light guide plate 2 are optically connected, and a rough finish that irregularly reflects when the entire surface of the light guide plate 2 is optically connected. I do.

In the radiation detecting apparatus according to the fifth embodiment, the detection efficiency for beta rays is increased by increasing the thickness of the scintillator around the main scintillator 1. The light from the sub scintillator 1a also reaches the light collector 3 through the light guide plate 2 like the light from the main scintillator 1, and is collected. Since the sub scintillator 1a is located on the side opposite to the detection surface, the main scintillator 1a
Scintillator 1a without deteriorating detection performance
Can be added.

Therefore, it is possible to collect more light from the scintillator thinned so that the background count by gamma rays is reduced, and to obtain higher detection efficiency for beta rays. In addition, uniform and high detection efficiency can be obtained regardless of the incidence position of the beta ray.

A radiation detecting apparatus according to a sixth embodiment of the present invention will be described with reference to FIG. That is, the main scintillator 1 and the sub-scintillator 1a having a small area are optically connected to the scintillator bonding surface 14 of the light guide plate 2 that has been subjected to the step processing. The position of the sub-scintillator 1a is set at the periphery of the main scintillator 1. The scintillator sticking surface 14 is cut into a convex shape so as to absorb a gap caused when sticking due to the thickness of the sub-scintillator 1a. The back surface 13 on the opposite side to the attachment surface has a mirror surface finish that totally reflects when the entire surface of the main scintillator 1, the sub-scintillator 1a and the light guide plate 2 is optically connected, and when the optical connection is very small, Rough surface with diffuse reflection.

In the radiation detecting apparatus according to the sixth embodiment, since there is no gap even if the sub-scintillator 1a has a thickness, light loss between the main scintillator 1 or the sub-scintillator 1a and the light guide plate 2 is reduced. Less.
In particular, when the entire surface of the main scintillator 1, the sub-scintillator 1a, and the light guide plate 2 are optically connected, light from the side surface of the sub-scintillator 1a also passes through the light guide plate 2, and high light-collecting efficiency is obtained.

Accordingly, it becomes possible to collect more light from a scintillator thinned so that the background count by gamma rays is reduced, and a higher detection efficiency for beta rays is obtained. In addition, uniform and high detection efficiency can be obtained regardless of the incidence position of the beta ray.

A radiation detecting apparatus according to a seventh embodiment of the present invention will be described with reference to FIG. That is, the main scintillator 1 and the sub-scintillator 1a having a small area are optically connected to the scintillator attachment surface 14 of the light guide plate 2 that has been subjected to the step processing. The position of the sub-scintillator 1a is set at the periphery of the main scintillator 1. The scintillator sticking surface 14 is cut into a convex shape so as to absorb a gap caused when sticking due to the thickness of the sub-scintillator 1a. The entire surface is optically connected only to the surface where the main scintillator 1 and the sub-scintillator 1a are respectively connected to the light guide plate 2,
The connection surface between the main scintillator 1 and the sub-scintillator 1a is not optically connected by an adhesive. The back surface 13 on the side opposite to the scintillator attachment surface is mirror-finished to totally reflect.

In the radiation detecting apparatus according to the seventh embodiment, the main scintillator 1 and the sub-scintillator 1
Since no substance other than air is interposed between “a” and the energy loss of the beta ray that does not contribute to light emission is reduced, the light emission amount is increased as compared with the sixth embodiment. Therefore, more light can be collected from a scintillator thinned so that the background count by gamma rays is reduced, and higher detection efficiency for beta rays can be obtained. In addition, uniform and high detection efficiency can be obtained regardless of the incidence position of the beta ray.

Next, a radiation detecting apparatus according to an eighth embodiment of the present invention will be described. That is, as shown in FIG. 7 which is a partial plan view of the detection unit, the sub-scintillator 1a having a smaller area than the main scintillator 1 is optically connected to the entire surface of the scintillator attachment surface 14 of the light guide plate 2 by an optical adhesive or the like. I do. The position of the sub-scintillator 1a is set at the periphery of the main scintillator 1. Sub scintillator 1
The reflecting material 15 is applied to portions other than the connection surface with the light collecting portion 3 of a.

In the radiation detecting apparatus according to the eighth embodiment, light directed toward the side surface of the sub-scintillator 1a is reflected by the reflector 15 into the small-area scintillator 1a, so that the main scintillator 1a is efficiently used. Alternatively, the light can be guided to the light guide plate 2. Therefore, more light can be collected from a scintillator thinned so that the background count by gamma rays is reduced, and higher detection efficiency for beta rays can be obtained. In addition, uniform and high detection efficiency can be obtained regardless of the location of the beta ray incidence.

Next, a radiation detecting apparatus according to a ninth embodiment of the present invention will be described. That is, as shown in FIG. 8, which is a plan view of the detection unit, a plurality of scintillators 1b and 1c are optically connected to the light guide plate 2 by an optical adhesive or the like instead of one scintillator. Further, a wavelength conversion type light guide 16 is used for the light collecting section 3. At this time, a scintillator 1b of a type whose emission wavelength is compatible with the absorption wavelength of the wavelength conversion type light guide 16 is positioned at the periphery of the surface to be measured, and the emission wavelength matches the absorption wavelength of the wavelength conversion type light guide 16. The other type of scintillator 1c is positioned at the center of the detection surface. The scintillators 1b and 1c are laid without gaps and optically adhered to each other, or are laid with a gap therebetween and a reflecting material is applied to the end faces of the scintillators 1b and 1c.

In the radiation detecting apparatus according to the ninth embodiment, the light from the scintillators 1b and 1c is
Can be led to the wavelength conversion type light guide 16 without waste. The output light amount of the wavelength conversion type light guide 16 is larger when the light from the scintillator 1b is absorbed.
Since the light from the scintillator 1c is larger than that when the light is absorbed, the beta-ray detection efficiency is higher when the light enters the scintillator 1b than when the light enters the scintillator 1c.

Therefore, according to the radiation detection apparatus of the present embodiment, it becomes possible to collect more light from a scintillator thinned so that the background count by gamma rays is reduced, and to obtain higher detection efficiency for beta rays. Can be In addition, uniform and high detection efficiency can be obtained regardless of the incidence position of the beta ray.

Next, a radiation detecting apparatus according to a tenth embodiment of the present invention will be described. That is, as shown in FIG. 9, which is a plan view of the detecting unit, a plurality of scintillators 1d are optically connected to the light guide plate 2 by using an optical adhesive or the like instead of one scintillator. Further, a wavelength conversion type light guide 16 is used for the light collecting section 3. At this time, a scintillator 1d of a type whose emission wavelength matches the absorption wavelength of the wavelength conversion type light guide 16 is positioned at the periphery of the detection surface, and the emission wavelength becomes closer to the center of the measurement target surface. A scintillator 1d of a type not adapted to the absorption wavelength of the guide 16 is located. Scintillator 1
d is spread without gaps and optically adhered to each other, or is spread with a gap and coated with a reflective material on the end face of the scintillator 1d.

In the radiation detecting apparatus according to the tenth embodiment, light from the scintillator 1d can be guided to the wavelength conversion type light guide 16 through the light guide plate 2 without waste. The output light amount of the wavelength conversion type light guide 16 is:
Since the case where the light from the scintillator 1d located in the peripheral part is absorbed is larger than the case where the light from the scintillator 1d located in the central part is absorbed, the detection efficiency of the beta ray is located in the peripheral part. The light incident on the scintillator 1d is larger than the light incident on the scintillator 1d located at the center.

Therefore, according to the radiation detecting apparatus of the present embodiment, it becomes possible to collect more light from a scintillator thinned so as to reduce the background count by gamma rays, and to obtain higher detection efficiency for beta rays. Can be In addition, uniform and high detection efficiency can be obtained regardless of the location of the beta ray incidence.

Next, a radiation detecting apparatus according to an eleventh embodiment of the present invention will be described. FIG. 10 is a plan view of the detection unit.
That is, instead of one scintillator, a plurality of scintillators 1e and 1f are optically connected to the light guide plate 2 by an optical adhesive or the like over the entire surface. At that time, the thick scintillator 1e is located at the periphery of the radiation detection surface, and the thin scintillator 1f is located at the center of the radiation detection surface. The scintillators 1e and 1f are laid without gaps and are optically bonded to each other, or are laid with a gap therebetween and a reflective material is applied to the end faces of the scintillators 1e and 1f.

In the radiation detecting apparatus according to the eleventh embodiment, light from the scintillators 1e and 1f can be guided to the wavelength conversion type light guide 16 through the light guide plate 2 without waste. Since the amount of light emitted from the scintillator 1e is larger than the amount of light emitted from the scintillator 1f, the beta ray detection efficiency is higher when the light enters the scintillator 1e than when the light enters the scintillator 1f.

Therefore, it becomes possible to collect more light from the scintillator thinned so that the background count by gamma rays is reduced, and to obtain higher detection efficiency for beta rays. In addition, uniform and high detection efficiency can be obtained regardless of the location of the beta ray incidence.

Next, a radiation detecting apparatus according to a twelfth embodiment of the present invention will be described with reference to FIG. 11, which is a plan view of the detecting section. That is, instead of one scintillator, a plurality of scintillators 1g are optically connected to the light guide plate 2 over the entire surface by an optical adhesive or the like. The thick scintillator 1g is positioned at the periphery of the radiation detection surface, and the thin scintillator 1g is positioned closer to the center of the measurement target surface. The scintillator 1g is laid without gaps and optically adhered to each other, or is laid with a gap therebetween and a reflective material is applied to the end face of the scintillator 1g.

In the radiation detecting apparatus according to this embodiment, light from the scintillator 1g can be guided to the wavelength conversion type light guide 16 through the light guide plate 2 without waste.
Since the light from the scintillator 1g located in the peripheral part is larger than the light from the scintillator 1g located in the central part, the detection efficiency of beta rays is better when the light enters the scintillator 1g located in the peripheral part. Is larger than when the light enters the scintillator 1g located at the center.

Therefore, it becomes possible to collect more sufficient light from a scintillator thinned so that the background count by gamma rays is reduced, and to realize higher detection efficiency for beta rays. In addition, uniform and high detection efficiency can be realized irrespective of the incidence position of the beta ray.

Next, a radiation detecting apparatus according to a thirteenth embodiment of the present invention will be described with reference to FIG. 12, which is a plan view of the detecting section. That is, instead of a single scintillator, a plurality of small area scintillators 1h are optically connected to the light guide plate 2 with an optical adhesive or the like over the entire surface. The scintillator 1h is laid without gaps and optically adhered to each other, or is laid with a gap and spread over the scintillator 1h.
A reflective material is applied to the end face of.

In the radiation detector of this embodiment, light from the scintillator 1h can be guided to the wavelength conversion type light guide 16 through the light guide plate 2 without waste.
Therefore, it becomes possible to collect more light from a scintillator thinned so that the background count by gamma rays is reduced, and higher detection efficiency for beta rays is realized. In addition, the use of a small-area scintillator facilitates the acquisition of materials and improves the product yield.

[0057]

According to the present invention, a large effective detection area,
It is possible to provide a radiation detector having low background count and uniform and high detection efficiency irrespective of the location of beta ray incidence.

[Brief description of the drawings]

FIGS. 1A and 1B show a radiation detecting apparatus according to a first embodiment of the present invention, wherein FIG. 1A is an overall configuration diagram, and FIG. 1B is a cross-sectional view taken along line bb of FIG.

FIG. 2 is a sectional view of a detection unit of the radiation detection device according to the second and third embodiments of the present invention.

FIG. 3 is a sectional view of a detection unit of a radiation detection device according to a fourth embodiment of the present invention.

FIG. 4 is a sectional view of a detection unit of a radiation detection device according to a fifth embodiment of the present invention.

FIG. 5 is a sectional view of a detection unit of a radiation detection device according to a sixth embodiment of the present invention.

FIG. 6 is a sectional view of a detection unit of a radiation detection device according to a seventh embodiment of the present invention.

FIG. 7 is a sectional view of a detection unit of a radiation detection device according to an eighth embodiment of the present invention.

FIG. 8 is a sectional view of a detection unit of a radiation detection device according to a ninth embodiment of the present invention.

FIG. 9 is a sectional view of a detection unit of a radiation detection device according to a tenth embodiment of the present invention.

FIG. 10 is a sectional view of a detection unit of a radiation detection device according to an eleventh embodiment of the present invention.

FIG. 11 is a sectional view of a detection unit of a radiation detection device according to a twelfth embodiment of the present invention.

FIG. 12 is a sectional view of a detection unit of a radiation detection device according to a thirteenth embodiment of the present invention.

FIG. 13 is a cross-sectional view showing a configuration of a conventional radiation detection device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Scintillator, 1a ... Sub scintillator, 1b ... Scintillator whose emission wavelength matches the light absorption peak of the wavelength conversion type light guide, 1c ... Scintillator whose emission wavelength deviates from the light absorption peak of the wavelength conversion type light guide, 1d: scintillators having mutually different emission wavelengths, 1e
... Thick scintillator, 1f ... Thin scintillator, 1g ...
Scintillators having different thicknesses from each other, 1h small area scintillator, 2 light guide plate, 3 light condensing section, 4 photoelectric conversion element,
5: Signal processing circuit, 6: Simultaneous counting circuit, 7: Interface circuit, 8: Detector container, 11: Sticking surface of scintillator and light guide plate, 12: Surface of scintillator, 13 ...
Back surface of light guide plate, 14: scintillator attachment surface of light guide plate subjected to step processing, 15: reflective material, 16: wavelength conversion type light guide, 22: scintillator, 23: light reflecting paint, 2
4 ... detector container, 25 ... photoelectric conversion element, 26 ... light shielding film.

Claims (7)

[Claims] 1. A thin plate-shaped scintillator arranged on a measurement surface, a light guide plate optically connected to a back surface of the scintillator to guide light, and a light condensing unit optically connected to a side surface of the scintillator. A radiation detecting device, comprising: a photoelectric conversion element optically connected to the light collecting unit; and a signal processing circuit connected to the photoelectric conversion element. 2. The radiation detecting apparatus according to claim 1, wherein the light guide plate covers the entire back surface of the scintillator, and the light condensing part is also optically connected to a side surface of the light guide plate. 3. The radiation detection apparatus according to claim 2, wherein the scintillator and the light guide plate are optically connected over the entire surface, and the back surface of the light guide plate is a mirror surface that totally reflects light. 4. The radiation detecting apparatus according to claim 2, wherein the scintillator and the light guide plate are partially optically connected, and the back surface of the light guide plate is a rough surface that diffusely reflects light. 5. A scintillator comprising: a main scintillator covering the entire radiation detection surface; and a sub-scintillator having a smaller area optically connected to the main scintillator;
3. The radiation detecting apparatus according to claim 2, wherein the sub-scintillator is disposed around the main scintillator. 6. The light collecting section is a wavelength conversion type light guide,
The scintillator is composed of a plurality of small-area scintillators, and the emission wavelength of the small-area scintillator provided at the center of the radiation detection surface is set to a wavelength slightly apart from the absorption wavelength of the light guide. 3. The radiation detecting apparatus according to claim 2, wherein an emission wavelength of the small area scintillator provided in the portion is set to a wavelength more suitable for an absorption wavelength of the light guide. 7. The light collecting section is a wavelength conversion type light guide,
Further, the scintillator is constituted by a plurality of small area scintillators, and the thickness of the small area scintillator provided at the central portion of the radiation detection surface is made smaller than the thickness of the small area scintillator provided at the peripheral portion of the radiation detection surface. The radiation detection apparatus according to claim 2, wherein: