WO2019062253A1 - Array-type large-area total radioactivity detection device - Google Patents

Abstract

An array-type large-area total radioactivity detection device comprises: a water-resistant protection material; at least one EJ-444 detector used to detect α and β signals, and to convert the detected α and β signals to optical signals; an organic glass member connected to the at least one E-J444 detector; a wavelength shifting optical fiber provided in the organic glass member; and a photomultiplier tube connected to the wavelength shifting optical fiber to obtain the optical signals transmitted by the wavelength shifting optical fiber. The detection device employs a dual surface detection structure and combines an optical fiber and a detector to simultaneously detect α and β radioactivity in water and discriminate between α and β radionuclides.

Description

Array type large area total discharge detecting device

Cross-reference to related applications

This application claims the priority of the Chinese patent application No. "201721253671.4" submitted by Tsinghua University on September 27, 2017, and the utility model name is "array type large area total discharge detecting device".

Technical field

The utility model relates to the technical field of environmental monitoring, in particular to an array type large area total discharge detecting device.

Background technique

The interaction between nuclear radiation and matter will prevent the dielectric atoms from being excited. When these excited atoms are de-excited back to their ground state, they will emit light pulses. This phenomenon is called flicker, and the device for detecting nuclear radiation based on this phenomenon. It is called a scintillation detector. In the detection of conventional alpha particles and beta particles, ZnS (Zinc Sulphur) and plastic scintillators act as sensitive elements for detecting alpha particles and beta particles, respectively. Since the direction of propagation of the scintillation light generated in the scintillator is random, it is not easy to collect and transmit, thereby affecting its detection efficiency.

In the related art, the measurement of the total alpha total beta activity is usually carried out by coupling the effective sensitive detection window of the photomultiplier tube directly or through the light guide to the surface of the scintillator. Although this method improves the detection efficiency of scintillation light, there are also obvious deficiencies. For example, if direct coupling is used, the effective detection window of the photomultiplier tube is limited, thereby limiting the detection area; if indirect coupling is used, The geometry of the detector becomes complicated and the size increases accordingly. At the same time, since the photomultiplier tube and the scintillator cannot be separated, in the irradiated test environment, the radiation and electromagnetic interference at the scene will be photoelectric. The multiplier tube has an effect. In addition, based on the consideration of waterproofing, anti-corrosion and anti-irradiation of the measuring elements of the immersed water measuring environment, the direct or indirect coupling of the scintillator and the photomultiplier tube is even less satisfactory.

In addition, based on the coupling measurement method of the optical fiber and the scintillator detection device, it is mostly applied to the monitoring of large-area surface contamination of β, and no water immersion measurement and simultaneous measurement of αβ are performed. Moreover, for the measurement of β-nuclides with low water content and total α and total β, it is sometimes necessary to carry out rapid measurement, especially in the case of unexpected situations, the conventional radiochemical analysis method is adopted at home and abroad, that is, through the “site Sampling + laboratory analysis is done in a way. However, the shortcomings of this type of method are: the sample pretreatment procedure is cumbersome, manual and time consuming, and the test results are often given after several days of sampling. Moreover, some countries have conducted on-line monitoring of radioactivity in water, but The detection limit is relatively high (total α: 0.5Bq/L, total β: 1.0Bq/L), so that it can not only meet the needs of low-level radionuclide measurement in water, but also has a low timeliness and needs to be solved.

Summary of the invention

The present invention aims to solve at least one of the technical problems in the related art to some extent.

Therefore, the object of the present invention is to provide an array type large-area total-discharge detecting device, which not only can improve the detection efficiency and collection efficiency of photoelectrons, but also can realize the measurement in accordance with the double-end readout mode of the optical fiber and remove the electronic noise. .

In order to achieve the above object, the present invention provides an array type large area total discharge detecting device, comprising: a waterproof protection material; at least one EJ444 detector for detecting an αβ signal, and converting the detected αβ signal into an optical signal a plexiglass, the plexiglass being connected to the at least one EJ444 detector; a wavelength converting fiber, the wavelength converting fiber being embedded in the plexiglass; a photomultiplier tube, the photomultiplier tube and the wavelength conversion The optical fibers are connected to transmit the optical signal through the wavelength conversion optical fiber.

According to the array type large-area total-discharge detecting device of the present invention, the simultaneous measurement of αβ radioactivity in the water body and the discrimination of the αβ radionuclide can be realized by the double-sided detector structure and the fiber-detector coupling method, thereby not only improving Photoelectron detection efficiency and collection efficiency, and the fiber double-end readout method can achieve measurement and remove electronic noise.

Further, the waterproof protection material comprises: an aluminum shell, a waterproof glue and a PVC (polyvinyl chloride) cladding.

Further, the at least one EJ444 detector comprises: an EJ212 scintillator detector for detecting beta particles; an EJ440 detector for detecting alpha particles; wherein the plexiglass is disposed on the EJ212 scintillator detector and Between the EJ440 detectors.

Further, the double-layered surface of the plexiglass is slotted and cross-sectioned in a staggered manner to couple the wavelength-converting fiber into the plexiglass using optical glue.

Further, the wavelength converting fiber is bitten by two pieces of plexiglass and read out signals from the middle.

Further, the array type large-area total-discharge detecting device further includes: a fiber bundler for bundling the wavelength-converting fiber and outputting the fiber of the fiber bundler through the grease and the photomultiplier tube at the rear end coupling.

Further, the array type large area total discharge detecting device further includes: a processing circuit, wherein the processing circuit is connected to the photomultiplier tube to obtain an electrical signal obtained by converting the optical signal by the photomultiplier tube, and The signal and the beta signal are counted and the spectral output is output, and the alpha signal and the beta signal are distinguished by a pulse amplitude discrimination technique for the output signal for nuclide identification.

Further, the at least one EJ444 detector has a sheet structure, the effective detection area of the at least one EJ444 detector is 0.18 m ² , and the thickness of the at least one EJ444 detector is 1 mm.

Further, the core of the wavelength conversion fiber has a high refractive index, and the cladding has a low refractive index and has a cross section of 1 mm x 1 mm.

Further, the composition of the at least one EJ444 detector comprises polycrystalline ZnS:Ag.

The additional aspects and advantages of the invention will be set forth in part in the description which follows in

DRAWINGS

The above and/or additional aspects and advantages of the present invention will become apparent and readily understood from

1 is a schematic structural view of an array type large area total discharge detecting device according to an embodiment of the present invention;

2 is a schematic view showing a double-end double-sided readout optical fiber burying manner according to an embodiment of the present invention;

3 is a schematic diagram of a double-ended center readout fiber embedding manner according to an embodiment of the present invention;

4 is a schematic diagram of double-ended readout of a single-piece detector fiber in accordance with an embodiment of the present invention.

Detailed ways

The embodiments of the present invention are described in detail below, and the examples of the embodiments are illustrated in the drawings, wherein the same or similar reference numerals are used to refer to the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the drawings are intended to be illustrative of the invention and are not to be construed as limiting.

An array type large area total discharge detecting device according to an embodiment of the present invention will be described below with reference to the accompanying drawings.

1 is a schematic structural view of an array type large area total discharge detecting device according to an embodiment of the present invention.

As shown in FIG. 1, the array type large-area total-discharge detecting device may include: a waterproof protective material, at least one EJ444 detector (shown as EJ444 detector 1 in the figure), plexiglass 2, wavelength conversion fiber 3, and photoelectric multiplication. tube.

Among them, at least one EJ444 detector is used to detect the αβ signal and convert the detected αβ signal into an optical signal. The plexiglass 2 is connected to at least one EJ444 detector. The wavelength conversion fiber 3 is buried in the organic glass 2. The photomultiplier tube is connected to the wavelength conversion fiber 3 to be transmitted through the wavelength conversion fiber 3 to obtain an optical signal. The device of the embodiment of the present invention can not only improve the detection efficiency and collection efficiency of photoelectrons, but also the method of double-end readout of the optical fiber can achieve measurement and remove electronic noise.

It will be appreciated that the EJ444 detector 1 can be used to simultaneously detect alpha beta radioactivity and convert the detected particles into optical signals. The coupling of both the plexiglass 2 and the wavelength converting fiber 3 is used to realize the collection of the optical signal, and the optical signal is transmitted to the photomultiplier tube, and the photomultiplier tube realizes the conversion of the optical signal to the electrical signal.

Optionally, in an embodiment of the present invention, as shown in FIG. 1 , the waterproof protection material comprises: an aluminum shell 4 , a waterproof rubber 5 and a PVC cladding layer 6 , wherein the aluminum shell 4 can effectively waterproof and protect the device. Prevent damage to the device; waterproof rubber 5 can effectively waterproof and protect equipment; PVC cladding 6 can protect the optical fiber and effectively waterproof. In addition, the waterproof protective material can be arranged in various ways. For example, the aluminum shell 4 can be disposed at the outermost layer of the array type large-area total discharge detecting device; the waterproof rubber 5 can be disposed between the aluminum shell 4 and the EJ444 detector 1. It is located under the aluminum shell 4; the PVC cladding layer 6 can be disposed at the boundary between the aluminum shell 4 and the wavelength converting fiber 3 for wrapping the wavelength converting fiber 3, which can be set by a person skilled in the art according to actual conditions. Make specific limits.

Further, in an embodiment of the present invention, as shown in FIG. 1, at least one EJ444 detector includes: an EJ212 scintillator detector 7 and an EJ440 detector 8.

Among them, the EJ212 scintillator detector 7 is used to detect β particles. The EJ440 detector 8 is used to detect alpha particles. Among them, the plexiglass 2 is disposed between the EJ212 scintillator detector 7 and the EJ440 detector 8.

Optionally, in an embodiment of the invention, at least one component of the EJ444 detector comprises polycrystalline ZnS:Ag.

Specifically, the EJ444 detector 1 is composed of the surface of the EJ212 scintillator detector 7 covering the EJ440 detector 8, and the plexiglass 2 is disposed between the EJ212 scintillator detector 7 and the EJ440 detector 8, thereby effectively improving the collection efficiency of photoelectrons. . Among them, the main component of the EJ440 detector 8 in the EJ444 detector 1 is polycrystalline ZnS:Ag. The EJ444 detector 8 can simultaneously measure alpha and beta radioactivity. The thin layer of ZnS:Ag can block the alpha particles produced by the decay of the radioactive material, and the beta particles produced by the decay of the radioactive material enter the EJ212 scintillator detector 7. Beta particles can be detected in the EJ212 scintillator detector 7.

Further, in an embodiment of the present invention, at least one EJ444 detector has a sheet structure, at least one EJ444 detector has an effective detection area of 0.18 m ² , and at least one EJ444 detector has a thickness of 1 mm.

That is to say, the EJ444 detector 1 is a sheet-like structure with an effective detection area of 0.18 m ² and a thickness of 1 mm, and the sheet structure can minimize the background count of natural γ radioactivity. The EJ444 detector 1 can also be referred to as a double-layer EJ444 detector. The embodiment of the present invention adopts a double-layer EJ444 detector structure, thereby effectively improving the detection efficiency of photoelectrons.

Further, in one embodiment of the present invention, the double-layered surface of the plexiglass 2 is slotted and cut in a staggered manner to couple the wavelength-converting fiber 3 into the plexiglass 2 using optical glue.

Specifically, as shown in FIG. 2, the apparatus of the embodiment of the present invention can couple the wavelength converting fiber 3 to the inside of the plexiglass 2 by using optical glue to grooving and splitting the double-layer surface of the plexiglass 2. The staggered groove is adopted on the double surfaces of the plexiglass 2, thereby effectively improving the toughness of the plexiglass 2.

Further, in one embodiment of the present invention, the wavelength converting fiber 3 is bitten by two sheets of plexiglass 2 and read out signals from the middle.

Alternatively, in one embodiment of the present invention, the core of the wavelength converting fiber 3 has a high refractive index, and the cladding has a low refractive index with a cross section of 1 mm x 1 mm.

Specifically, as shown in FIG. 3, the difference from the reading mode of FIG. 2 is that the wavelength converting fiber 3 is bitten by the two sheets of plexiglass 2 and the signals are read out from the center.

Further, in an embodiment of the present invention, the apparatus of the embodiment of the present invention further includes: an optical fiber bundler 9. The fiber bundler 9 is used for bundle finishing the wavelength conversion fiber 3, and the wavelength conversion fiber 3 output from the fiber bundler 9 is coupled to the photomultiplier tube at the rear end by a silicone grease.

Specifically, as shown in FIG. 4, the device of the embodiment of the present invention uses a total of 10 EJ444 detectors 1, wherein 5 EJ444 detectors 1 serve as a detecting unit, and the device of the embodiment of the present invention uses a buncher 9 The wavelength converting fiber 3 drawn from each detecting unit is subjected to bundle finishing, and the wavelength converting fiber 3 output from the fiber bundler 9 is coupled to the photomultiplier tube 10 at the rear end by a material such as silicone grease.

Further, in an embodiment of the present invention, the apparatus of the embodiment of the present invention further includes: a processing circuit. Wherein, the processing circuit is connected to the photomultiplier tube 10 to obtain an electrical signal obtained by converting the optical signal by the photomultiplier tube 10, and counting and spectrum output of the alpha signal and the beta signal, and a pulse amplitude discrimination technique for the output signal. The alpha signal and the beta signal are distinguished for nuclide identification.

That is to say, the photomultiplier tube 10 converts the optical signal into an electrical signal and outputs it to a subsequent electronic circuit, performs counting and energy spectrum output of the alpha signal and the beta signal, and distinguishes the alpha signal and the beta by the pulse amplitude discrimination technique of the output signal. Signal, for nuclide identification.

The working principle of the array type large-area total-discharge detecting device of the embodiment of the present invention will be described in detail below.

In the embodiment of the present invention, the EJ444 detector 1 is first placed in the water body of the water tank, and the EJ444 detector 1 detects the αβ ray and converts the energy of the ray radiation into an optical signal. Then, the optical signal converted by the EJ444 detector 1 is irradiated into the plexiglass 2 and the wavelength converting fiber 3, and the optical signal is transmitted to the subsequent photomultiplier tube 10 through the wavelength converting fiber 3, and the photomultiplier tube 10 converts the optical signal into electricity. The signal is measured in accordance with the output signals of the photomultiplier tubes 10 at both ends. Finally, the electrical signal is transmitted to subsequent electronic circuits for counting and energy spectrum output, and the αβ signal is discriminated by an algorithm.

According to the embodiment of the present invention, the array type large-area total-discharge detecting device can realize the simultaneous measurement of αβ radioactivity in the water body and the discrimination of the αβ radionuclide by means of the double-sided detector structure and the fiber-detector coupling. Therefore, not only the detection efficiency and collection efficiency of the photoelectron are improved, but also the method of double-end readout of the optical fiber can achieve measurement and remove electronic noise.

Moreover, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, features defining "first" and "second" may include at least one of the features, either explicitly or implicitly. In the description of the present invention, the meaning of "a plurality" is at least two, such as two, three, etc., unless specifically defined otherwise.

In the present invention, the terms "installation", "connected", "connected", "fixed" and the like shall be understood broadly, and may be fixed or detachable, for example, unless otherwise explicitly defined and defined. Connected, or integrated; can be mechanical or electrical; can be directly connected, or indirectly connected through an intermediate medium, can be the internal communication of two components or the interaction of two components, unless otherwise Clearly defined. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood on a case-by-case basis.

In the present invention, the first feature "on" or "under" the second feature may be a direct contact of the first and second features, or the first and second features pass through an intermediate medium, unless otherwise explicitly stated and defined. Indirect contact. Moreover, the first feature "above", "above" and "above" the second feature may be that the first feature is directly above or above the second feature, or merely that the first feature level is higher than the second feature. The first feature "below", "below" and "below" the second feature may be that the first feature is directly below or obliquely below the second feature, or merely that the first feature level is less than the second feature.

In the description of the present specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" and the like means a specific feature described in connection with the embodiment or example. A structure, material or feature is included in at least one embodiment or example of the invention. In the present specification, the schematic representation of the above terms is not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. In addition, various embodiments or examples described in the specification, as well as features of various embodiments or examples, may be combined and combined.

Although the embodiments of the present invention have been shown and described, it is understood that the embodiments described above are illustrative and are not to be construed as limiting the scope of the invention. Variations, modifications, substitutions and variations of the above-described embodiments are possible.

Claims (9)

1. An array type large area total discharge detecting device, comprising:

   Waterproof protective material;

   At least one EJ444 detector for detecting an αβ signal and converting the detected αβ signal into an optical signal;

   a plexiglass, the plexiglass being connected to the at least one EJ444 detector;

   a wavelength converting fiber, the wavelength converting fiber being buried in the plexiglass;

   a photomultiplier tube, the photomultiplier tube being coupled to the wavelength converting fiber for transmitting the optical signal through the wavelength conversion fiber.
2. The array type large-area total discharge detecting device according to claim 1, wherein the waterproof protection material comprises: an aluminum shell, a waterproof glue and a PVC cladding.
3. The array type large area total discharge detecting device according to claim 1, wherein said at least one piece of EJ444 detector comprises:

   EJ212 scintillation detector for detecting beta particles;

   EJ440 detector for detecting alpha particles;

   Wherein, the plexiglass is disposed between the EJ212 scintillator detector and the EJ440 detector.
4. The array type large-area total discharge detecting device according to claim 3, wherein the double-layer surface of the plexiglass is slotted and cut in a staggered manner to convert the wavelength using optical glue. The fiber is coupled into the plexiglass.
5. The array type large-area total discharge detecting device according to claim 3 or 4, wherein the wavelength conversion optical fiber is bitten by two pieces of organic glass and the signals are read out from the middle.
6. The apparatus of claim 1 further comprising:

   And a fiber bundler for bundling the wavelength converting fiber and coupling the fiber outputted by the fiber bundle to the photomultiplier tube at the back end through a silicone grease.
7. The apparatus of claim 1 further comprising:

   a processing circuit, the processing circuit is coupled to the photomultiplier tube to obtain an electrical signal obtained by converting the optical signal by the photomultiplier tube, and counting and spectrally outputting the alpha signal and the beta signal, and The pulse amplitude discrimination technique of the output signal distinguishes between the alpha signal and the beta signal for nuclide identification.
8. The array type large area total discharge detecting device according to claim 1, wherein the at least one EJ444 detector has a sheet structure, and the effective detection area of the at least one EJ444 detector is 0.18 m ² , At least one EJ444 detector has a thickness of 1 mm.
9. The array type large-area total discharge detecting device according to claim 1, wherein the core of the wavelength conversion fiber has a high refractive index, and the cladding has a low refractive index and a cross section of 1 mm × 1 mm.

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