JPH0774829B2 - Radiation detection device and radiation detection optical transmission device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention is used for detecting and measuring the presence or absence of radiation in industries and research institutions that use radioactive materials such as the nuclear industry, radiology, nondestructive inspection, and synchrotron radiation facilities. The present invention relates to a radiation-sensitive emission wavelength conversion output device.

[Prior Art] When detecting or measuring radiation, in the prior art, radiation energy is converted into an electric signal by some means,
A variety of things have been put into practical use, such as those that are displayed on an indicator by processing the signal, that are converted into sound by utilizing the ionizing discharge action, and film badges that utilize the radiation sensitive action.

[Problems to be Solved by the Invention] However, these conventional radiation detection devices and measurement methods are
It requires electrical processing and a special reading device, and therefore requires a complex signal processing system and cannot be used alone anytime anywhere. Further, although a simple type small dosimeter has been developed, it requires a power source such as a battery and has a limited use time, and it is expensive for making it an electronic device.

The present invention has been made in view of the above circumstances, does not require a power supply, does not require electrical processing, a special reading device, or signal processing, and can be used independently anytime and anywhere, and a method of use. It is an object of the present invention to provide an inexpensive radiation detection device that is simple and has a display function of notifying the presence of radiation.

[Means for Solving the Problems] In order to achieve the above object, the radiation detection apparatus of the present invention comprises a scintillator layer which emits fluorescence upon irradiation with radiation.
The scintillator is provided with a radiation-sensitive emission wavelength converter which comprises a fluorescent plastic optical fiber that absorbs fluorescence emitted by the scintillator, excites fluorescence of different wavelengths, collects and transmits the light, and, if necessary, the converter. The detection light from is transmitted to a point separated by an optical fiber having a microlens.

[Operation] According to the configuration of the present invention, the scintillator emits fluorescence when irradiated with radiation. This fluorescence excites the fluorescent plastic optical fiber to emit light, collects the emitted light, transmits the light, and outputs it to the end of the fiber. Since this light is converted to the long wavelength side, the presence and intensity of radiation can be identified by color and brightness.

[Embodiment] Hereinafter, a detailed description of the present invention will be given with reference to the drawings showing each embodiment.

FIG. 1 is a side view showing a schematic configuration of a radiation-sensitive emission wavelength converter showing an embodiment of the radiation detecting apparatus of the present invention.
In FIG. 1, reference numeral 1 is a radiation-sensitive emission wavelength converter. In this example, the radiation-sensitive emission wavelength converter 1 is provided with a light reflection plate 3 on the upper surface and the lower surface of a scintillator 2 having a columnar shape (a cylindrical shape is illustrated, but it may be a prismatic shape or a flat plate shape).
A translucent optical member (for example, glass) 4 is provided on the side surface of the columnar scintillator 2, and a fluorescent plastic optical fiber 5 is attached around the side wall surface of the optical member 4. An annular optical fiber 7 for blocking back light is arranged at the upper end of the fluorescent plastic optical fiber 5, but the output end of the upper end of the fluorescent plastic optical fiber 5 is exposed as a light emitting surface.

In addition, a light blocking member that blocks light emission is arranged at the lower end of the fluorescent optical fiber 5. Reference numeral 6 denotes a light shielding member that shields the back light and also has a function of reflecting the light leaked from the scintillator 2.

Further, FIG. 5 shows the radiation-sensitive emission wavelength converter 1 of FIG.
It is an explanatory view for explaining the operation of.

In FIG. 5, when the radiation A to be detected is incident on the radiation-sensitive emission wavelength converter 1, the scintillator 2 emits light and outputs light B, and this light B is incident on the fluorescent plastic optical fiber 5. The light C having an emission wavelength spectrum different from that of the incident light B is fluorescently excited, the excited light C is transmitted through the fluorescent plastic optical fiber 5, and the light D is output to the output end of the fluorescent plastic optical fiber 5. It

In the present invention, an organic scintillator, an inorganic scintillator or a liquid scintillator can be used as the scintillator 2, and the shape of the scintillator 2 can be arbitrarily selected. The scintillator 2 is, for example, a commercially available NaI scintillator, 2,5-diphenyloxazole (called DPO), 1,4-bis-2- (5-phenylosazoli) benzene (called POPOP) containing a mixed solution of toluene and kynylene. A liquid scintillator can be used.
As the light reflecting plate 3, a white member (for example, one coated with magnesium oxide) can be used. As the cylindrical translucent optical member 4, an optical material that transmits light of the emission wavelength of the scintillator 2 is commercially available, and this can be used.

The fluorescent plastic optical fiber 5 is, for example, Optectron (trade name) marketed by Nippon Petrochemical Co., Ltd.
Can be used. There are six types of the fluorescent plastic optical fiber 5, and since the excitation light wavelength regions are different from each other, an effective end point light emission output of the fluorescent plastic optical fiber can be obtained by matching the light emission characteristics of the scintillator 2. it can. The end point opposite to the light emission output end of the fluorescent plastic optical fiber 5 is shielded by a white member.

As the light-shielding member 6, a thin aluminum container whose inner surface is coated with a white member (eg, magnesium oxide) can be used.

The optical filter 7 is for removing the light of the excitation light wavelength of the fluorescent plastic optical fiber 5 from the back light, and a commercially available optical filter can be used.

The fluorescent plastic optical fiber 5 described above can also output in two stages by adopting two kinds of fluorescent plastics having different fluorescence excitation wavelength ranges. That is, NaI (Tl) is added to the scintillator 2.
FIG. 4 (a) shows the emission wavelength spectrum in the case of adopting, which has a long skirt of the spectrum on both sides with 4100Å as the peak wavelength. Assuming that the product numbers F201 and F202 shown in FIG. 4 (b) are adopted for the fluorescent plastic optical fiber 5, the emission wavelength of the scintillator 2 and the excitation wavelength of the F201 are in good agreement, but the emission wavelength of the scintillator 2 is F202. Sensitive to long wavelengths. However, the amount of sensitive incident light on the F202 is small.

Therefore, F201 emits light at a low radiation dose rate. As the radiation dose rate becomes higher, the amount of light emitted by the scintillator 2 increases, which increases the amount of light emitted on the long wavelength side of the excitation wavelength region of F202, leading to the emission and color development of F202. Therefore, it is possible to display the output in two steps, that is, the low radiation dose rate and the high radiation dose rate.

In addition, silicon grease (for example, optical cement manufactured and sold by Applied Light Research Institute Co., Ltd. (trade name) is used in the void portion of the light-transmitting optical member 4 and the light-shielding member 6 excluding the space occupied by the fluorescent plastic optical fiber 5. ), The efficiency of luminescent color development at the output end is improved.

FIG. 2 (a) is a side view showing a schematic configuration of a radiation-sensitive emission wavelength converter which is another embodiment of the present invention, and FIG. 2 (b) is a plan view of FIG. 2 (a). In FIG. 2, the emission output of two wavelengths is obtained according to the incident radiation intensity.

In FIG. 2 (a), 11 is a radiation-sensitive emission wavelength converter. In this example, the radiation-sensitive light emission wavelength converter 11 has a columnar (cylindrical shape is illustrated, but may be prismatic or flat plate-shaped) circular column scintillator 8 and a cylindrical scintillator 12 with the light reflection plates 3 on the upper and lower surfaces. The translucent optical member (for example, glass) 4 is arranged on the outer side wall portions of the ring-shaped scintillator 8 and the columnar scintillator 12, and the double-sided reflector 3 is arranged on the inner side wall portion of the ring-shaped scintillator 8. Cylinder scintillator
A fluorescent plastic optical fiber 5 is attached to the outside of the optical member of the outer wall of each of 12 and the ring-shaped column scintillator 8 in the same manner as in the embodiment of FIG. Here, the annular pillar scintillator 8 and the cylindrical scintillator 12 are
Different volumes (further different types of scintillators can be used) are used so that the amount of emitted light varies depending on the radiation intensity, and the fluorescent plastic optical fibers 5 attached to each have different emission wavelengths.

Reference numeral 6 denotes a light-shielding member having an inner surface having a reflecting function, and a thin plate-shaped aluminum container coated with a white member (for example, magnesium oxide) can be used.

The optical filter 7 corresponds to the fluorescent plastic optical fiber 5, and each fluorescent plastic optical fiber 5 corresponds to each excitation light wavelength in order to prevent the fluorescent plastic optical fiber 5 from emitting light with the excitation light wavelength in the back light. The optical filter can be used.

In FIG. 2, there are two scintillators with different volumes.
The scintillator emits light in proportion to the volume of the scintillator and the incident amount of radiation. The cylindrical columnar scintillator 12 in the center is smaller than the cylindrical columnar scintillator 8 in the outer shell. Both emit light when exposed to radiation, but the amount of light emitted is determined according to the volume of each scintillator. That is, when receiving the same radiation flux, the central cylindrical scintillator
12 emits less light than the outer cylindrical toroidal column scintillator 8. These emissions are fluorescent plastic optical fibers
The wavelengths are converted and output by 5a and 5b, but the output of the fluorescent plastic optical fiber 5a wound around the center is smaller than the output of the fluorescent plastic optical fiber 5b wound outside. That is, it is dark. Due to this difference in brightness, two-step display is possible.

In other words, while the radiation dose rate is low, only the outer fluorescent plastic optical fiber 5b emits light, but the fluorescent plastic optical fiber 5a at the center has a small emission amount, so it cannot be visually recognized. When the height becomes high, both of them shine and become visible. The two types of fluorescent plastic optical fibers 5a and 5b can be made more distinguishable by distinguishing colors by making the emission colors different.

Thus, it is possible to display in two steps.

In this detection, the annular column scintillator 8, the column scintillator 12, the light reflection plate 3, the translucent optical member 4, the translucent plastic optical fiber 5, the light shielding member 6, and the optical filter 7 are the same as those described above. The radiation-sensitive emission wavelength converter 1 shown in FIG. 1 has the same or the same function as that of the radiation-sensitive emission wavelength converter 1, and the method of detecting the radiation is the same as that in the case of FIG.

Although the present invention is intended for γ rays, neutron rays, β
It is obvious that it can be applied to X-ray and X-ray. The shape is also free.

Further, FIG. 3 is an explanatory view showing an embodiment of the radiation detecting optical transmission device of the present invention. Except for the optical filter 7 in FIGS. 1 and 2, each output end of the fluorescent plastic optical fiber 5 is shown. A device for transmitting the light output from the device to a separated point by mounting a microlens 9 as an optical lens and connecting an optical transmission optical fiber 10 to
Obviously, it can be easily realized by the existing optical transmission technology. Further, when used as a simple radiation detection optical transmission device, the number of fluorescent plastic optical fibers 5 need not be large, and may be one.

By the way, the present inventors have confirmed that γ-ray irradiation of about 1 R / Hr has a brightness that can be visually recognized even under incandescent light at the output end of one fluorescent plastic optical fiber.

FIG. 4 (a) shows NaI (T
1) shows an emission wavelength spectrum, and FIG. 6B is a diagram showing an example of light absorption and emission characteristics of the fluorescent plastic optical fiber. It can be seen from FIG. 4 that in the case of the NaI (Tl) scintillator, the fluorescent plastic optical fiber that emits green light with the product number F201 is suitable.

[Effects of the Invention] As described above, in the radiation-sensitive light emission wavelength converter in the radiation detector of the present invention, the fluorescent scattered light emitted by the scintillator upon incidence of radiation is wavelength-converted by the fluorescent plastic optical fiber, and condensed. By transmitting the light, the light can be confirmed with the naked eye at the output end of the fluorescent plastic optical fiber, and it can be a very simple and inexpensive display device that does not require a power supply, a signal processing system, and an analysis system. . Further, it is possible to realize a radiation detection optical transmission device that does not require photoelectric conversion in the detection unit.

[Brief description of drawings]

FIG. 1 is a side view showing a schematic configuration of a radiation-sensitive emission wavelength converter showing an embodiment of the radiation detecting apparatus of the present invention, and FIG. 2 (a) is a radiation-sensitive emission wavelength which is another embodiment of the present invention. The side view which shows the schematic structure of a converter, the figure (b) is the same plan view, FIG. 3 is the explanatory view showing one embodiment of the radiation detection optical transmission device of the present invention, and FIG. 4 (a) is the scintillator. As an example of the emission of NaI (Tl), an emission wavelength spectrum of NaI (Tl) is shown. FIG. 5 (b) is a diagram showing an example of light absorption and emission characteristics of a fluorescent plastic optical fiber, and FIG. It is explanatory drawing explaining the operation | movement of the radiation sensitive emission wave converter 1 of FIG. In the figure. 1,11: Radiation-sensitive emission wavelength converter 2,8,12: Scintillator 3: Light reflector 4: Translucent optical member 5: Fluorescent plastic optical fiber 6: Shading member 7: Optical filter 6: Ring cylinder Scintillator 9: Microlens 10: Optical transmission optical fiber 12: Cylindrical scintillator 13: Radiation detection optical transmission device

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshihiro Atsumi 2-4-1, Shiba Park, Minato-ku, Tokyo Inside Mitsubishi Harajiki Industry Co., Ltd. (72) Inventor Katsumi Urayama 1-chome Kitabukuro-cho, Omiya City, Saitama Prefecture 297 Mitsubishi Nuclear Industry Co., Ltd. Nuclear Development Center Omiya Research Center (72) Inventor Michio Wakahara 1-chome, Kitabukurocho, Omiya City, Saitama 297 Mitsubishi Nuclear Industry Co., Ltd. Nuclear Development Center Omiya Research Center

Claims (3)

[Claims] 1. A layer containing a solid or liquid scintillator which emits fluorescence upon irradiation with radiation, and absorbs fluorescence emitted by this scintillator to excite fluorescence on the long wavelength side to collect light.
It comprises a radiation-sensitive emission wavelength converter consisting of at least one fluorescent plastic optical fiber for light transmission, the radiation-sensitive emission wavelength converter comprising a reflector for preventing light leakage from the scintillator and a fluorescent plastic optical fiber. A tip of the fluorescent plastic optical fiber, which is provided with a translucent optical member for transmitting fluorescence emission due to incidence of radiation and which is covered with a back light shielding member having a light reflecting function with respect to the inside of the converter. The radiation detecting device, wherein the output part is covered with an optical filter for blocking the excitation wavelength light in the back light. 2. The radiation-sensitive light emission wavelength converter according to claim 1, wherein a layer containing a plurality of scintillators having different volumes is provided so that the radiation dose level can be output and displayed in a plurality of steps. Radiation detector. 3. An optical fiber equipped with a microlens is connected to each output end of each fluorescent plastic optical fiber in the radiation detecting apparatus according to claim 1 or 2, and is separated from the radiation detector. A radiation detection optical transmission device characterized by transmitting an output to a designated point.