阅读说明：本技术 一种用于放射性气体核素测量的闪烁体探测器 (Scintillator detector for measuring radioactive gas nuclide ) 是由 李奇 王世联 贾怀茂 赵允刚 樊元庆 张新军 于 2021-02-07 设计创作，主要内容包括：本发明涉及一种用于放射性气体核素测量的闪烁体探测器,探测器包括双面镀膜的塑料闪烁体圆片、双面镀膜的塑料闪烁体圆筒、充气管路、阀门、光电倍增管、铝壳和碳纤维底盖。塑料闪烁体圆片和塑料闪烁体圆筒的外表面镀膜材料为反光性好的铝、银等金属材料,内表面镀膜材料为透光性好的三氧化二铝、二氧化硅等轻质无机材料。双面镀膜的塑料闪烁体圆片、双面镀膜的塑料闪烁体圆筒、充气管路和阀门组成中空的圆柱体密闭容器,与光电倍增管耦合后用铝壳封装成探测器,铝壳底部为碳纤维底盖。该探测器在保证具有较高的探测效率的情况下,减小了样品的吸附效应。(The invention relates to a scintillator detector for measuring radioactive gas nuclide, which comprises a plastic scintillator wafer with a coated film on two sides, a plastic scintillator cylinder with a coated film on two sides, an air charging pipeline, a valve, a photomultiplier, an aluminum shell and a carbon fiber bottom cover. The outer surface coating materials of the plastic scintillator wafer and the plastic scintillator cylinder are metal materials with good light reflection, such as aluminum, silver and the like, and the inner surface coating materials are light inorganic materials with good light transmission, such as aluminum oxide, silicon dioxide and the like. The detector is characterized in that a hollow cylindrical closed container is composed of a plastic scintillator wafer with a film coated on two sides, a plastic scintillator cylinder with a film coated on two sides, an inflation pipeline and a valve, the hollow cylindrical closed container is coupled with a photomultiplier tube and then packaged into a detector by an aluminum shell, and the bottom of the aluminum shell is a carbon fiber bottom cover. The detector reduces the adsorption effect of the sample under the condition of ensuring higher detection efficiency.)

1. A scintillator detector for radioactive gas nuclide measurements, characterized by: the device comprises a plastic scintillator wafer (11) with a coated film on the double surface, a plastic scintillator cylinder (12) with a coated film on the double surface, a photomultiplier (13) and an aluminum shell, wherein the plastic scintillator wafer with the coated film on the double surface and the plastic scintillator cylinder with the coated film on the double surface form a hollow cylinder closed container; the bottom of the plastic scintillator cylinder with the double-sided coating is coupled with the photomultiplier and then packaged in an aluminum shell.

2. The scintillator detector for radioactive gas nuclide measurement as in claim 1, characterized in that: and the inner and outer surfaces of the plastic scintillator wafer and the plastic scintillator cylinder are plated with films made of different materials.

3. The scintillator detector for radioactive gas nuclide measurement as in claim 1, characterized in that: except the outer surface of the bottom of the plastic scintillator cylinder, the outer surface coating materials of the plastic scintillator wafer and the outer surface coating materials of the side wall of the plastic scintillator cylinder are aluminum or silver.

4. The scintillator detector for radioactive gas nuclide measurement as in claim 1, characterized in that: the inner surface coating materials of the plastic scintillator wafer and the plastic scintillator cylinder are light inorganic materials with good light transmittance.

5. The scintillator detector for radioactive gaseous nuclide measurement according to claim 1, or 2, or 3, or 4, characterized in that: the side wall of the plastic scintillator cylinder is connected with a valve through an inflation pipeline.

6. The scintillator detector for radioactive gaseous nuclide measurement as in claim 5, wherein: the top of the aluminum shell is provided with a carbon fiber cover.

7. The scintillator detector for radioactive gaseous nuclide measurement as in claim 5, wherein: the surface of the bonding part of the plastic scintillator cylinder and the plastic scintillator wafer is not coated with a film.

8. The scintillator detector for radioactive gaseous nuclide measurement as in claim 5, wherein: the surface of one end of the plastic scintillator cylinder coupled with the photomultiplier is not coated with a film.

9. The scintillator detector for radioactive gaseous nuclide measurement as in claim 3, wherein: the inner surface coating materials of the plastic scintillator wafer and the plastic scintillator cylinder are aluminum oxide or silicon dioxide.

10. The scintillator detector for radioactive gas nuclide measurement as in claim 1, characterized in that: the inner surfaces of the plastic scintillator wafer and the plastic scintillator cylinder are coated with the films as thin as possible, so that the adsorption effect of xenon on the inner surfaces is reduced, the fluorescence generated by beta rays on the plastic scintillator can be ensured to permeate, and the blockage to the beta rays is reduced; the plastic scintillator wafer and the outer surface coating film of the plastic scintillator cylinder are as thin as possible, uniform and seamless, and the plastic scintillator is ensured not to leak light.

Technical Field

The invention belongs to the field of atmospheric radiation environment monitoring and nuclear facility safe operation monitoring, and particularly relates to a scintillator detector for radioactive gas nuclide measurement, in particular to a double-sided coated plastic scintillator detector for radioactive gas nuclide measurement, and particularly relates to radioactive gas nuclide beta-ray measurement.

Background

The monitoring of radioactive xenon isotopes in the atmosphere has important significance for the safe operation of nuclear facilities and the monitoring of nuclear-related activities. The activity measurement of the trace radioactive gas is carried out, the detection sensitivity of the gas nuclide activity measurement is improved, valuable data can be provided for nuclear accident early warning, emergency and evaluation, and the method plays a positive role in protecting the public and protecting the radiation safety of the environment.

The beta-gamma coincidence measurement method is a gas radionuclide measurement method with high detection sensitivity, and the existing beta detector is difficult to adjust the gains of two photomultiplier tubes to be consistent due to the arrangement of the photomultiplier tubes at two ends, has poor energy resolution, adopts Teflon material as a reflecting layer, has the detection efficiency of beta rays of about 70 percent, and cannot meet the measurement of samples with larger volume due to smaller volume. In addition, the xenon adsorbed on the inner surface of the plastic scintillator detector affects the next sample, and the detection efficiency needs to be further improved.

Disclosure of Invention

The invention provides a scintillator detector for measuring radioactive gas nuclide, which aims to solve the technical problems that: reduce xenon adsorption effect and improve beta ray detection efficiency.

In order to solve the above technical problem, the present invention provides a scintillator detector for radioactive gas nuclide measurement, characterized in that: the device comprises a plastic scintillator wafer (11) with a coated film on the double surface, a plastic scintillator cylinder (12) with a coated film on the double surface, a photomultiplier (13) and an aluminum shell, wherein the plastic scintillator wafer with the coated film on the double surface and the plastic scintillator cylinder with the coated film on the double surface form a hollow cylinder closed container; the bottom of the plastic scintillator cylinder with the double-sided coating is coupled with the photomultiplier and then packaged in an aluminum shell.

Has the advantages that: 1. the plastic scintillator adopts the differential coating on the inner surface and the outer surface, the metal coating is adopted on the outer surface, the fluorescence reflection efficiency is enhanced, the high-efficiency detection of beta rays is realized, and the detection efficiency of conversion electrons in 129keV is more than 99 percent.

2. The inner surface is plated with light inorganic material with good light transmittance, and the adsorption effect of xenon on the inner surface is reduced from 5% to below 1%.

Drawings

FIG. 1 is a schematic view of a double-sided coated plastic scintillator;

FIG. 2 is a schematic structural view of a double-sided coated plastic scintillator detector before assembly;

FIG. 3 is a schematic view of the assembled double-sided coated plastic scintillator detector;

FIG. 4 is a gamma spectrum before and after a nitrogen flush;

FIG. 5 is a raw gamma spectrum and a coincidence gamma spectrum of the 131mXe sample;

wherein 1, the outer surface of the plastic scintillator wafer is plated with a metal film; 2-plating the inner surface of the plastic scintillator wafer with a light inorganic material film with good light transmittance; 3-uncoated plastic scintillator disk edge (to bond to plastic scintillator cylinder); 4-plastic scintillator cylinder bonding without coating; 5, bonding the circular hole of the inflation pipeline; 6-plating the inner surface of the plastic scintillator cylinder with a light inorganic material film with good light transmission; 7-plating the outer surface of the cylindrical side wall of the plastic scintillator with the metal film; 8-uncoated plastic scintillator cylinder bottom (coupled to photomultiplier tube); 9-an inflation pipeline; 10-a valve; 11-plastic scintillator wafer with double-sided coating; 12-plastic scintillator cylinder with double-sided coating; 13-a photomultiplier tube; 14-high voltage interface; 15-signal interface; 16-a carbon fiber cover; 17-packaging the aluminum shell; 18-gamma spectroscopy before nitrogen flushing; 19-gamma energy spectrum after nitrogen flushing; 20-original gamma energy spectrum; 21-coincidence with the gamma energy spectrum.

Detailed Description

In order to make the objects, contents and advantages of the present invention clearer, the following detailed description of the embodiments of the present invention is provided.

The invention provides a scintillator detector for measuring radioactive gas nuclide, which comprises: the double-sided coated plastic scintillator wafer 11, the double-sided coated plastic scintillator cylinder 12, the gas-filled pipeline 9, the valve 10, the photomultiplier 13, the aluminum shell 17 and the carbon fiber cover 16 form a hollow cylinder closed container;

and the inner and outer surfaces of the double-sided coated plastic scintillator wafer and the plastic scintillator cylinder are coated with films made of different materials.

Except for the outer surface of the bottom of the plastic scintillator cylinder which needs to be coupled with the photomultiplier and the bonding part of the plastic scintillator cylinder and the plastic scintillator wafer, the coating materials on the outer surfaces of the plastic scintillator wafer and the plastic scintillator cylinder are metal materials with good light reflection effect, such as aluminum or silver, and the like, the coating is as thin as possible, uniform and seamless, and the plastic scintillator is ensured not to leak light.

The inner surfaces of the plastic scintillator wafer and the plastic scintillator cylinder are both plated with light inorganic materials (such as aluminum oxide, silicon dioxide and the like) with good light transmittance, and the plated films are as thin as possible, so that the adsorption effect of xenon on the inner surface is reduced, the fluorescence generated by the plastic scintillator through beta rays is ensured, and the blockage to the beta rays is reduced.

The plastic scintillator wafer and the plastic scintillator cylinder after being coated with the film are bonded by epoxy resin with good light transmittance, the inflation tube is bonded by epoxy resin with good light transmittance and a round hole in the side wall of the plastic scintillator cylinder, the bottom of the plastic scintillator cylinder (the side without being coated with the metal film) is coupled with the photomultiplier, and then is packaged in an aluminum shell to form the plastic scintillator detector with the carbon fiber cover, and the top of the aluminum shell is provided with the carbon fiber cover to reduce the absorption of low-energy X rays and gamma rays during coincidence measurement.

FIGS. 1-3 are schematic structural views of a double-sided coated plastic scintillator detector according to the present invention, in which the diameter of the plastic scintillator disc is 50mm and the thickness thereof is 2mm (reduced absorption of low-energy X-rays and gamma-rays). An aluminum film 1 with the thickness of 10 mu m is plated on the outer surface; the inner surface is plated with an aluminum oxide film concentric circle 2 with the diameter of 40mm and the thickness of 400 nm; the circular ring part with 5mm of edge is not coated with the film 3.

The outer diameter of the plastic scintillator cylinder is 50mm, the inner diameter is 40mm, and the wall thickness is 5 mm. The surface of the bonding part of the plastic scintillator cylinder and the plastic scintillator wafer is not coated with a film 4; a through hole 5 with the diameter of 2mm is formed in the side wall of the plastic scintillator cylinder, and a gas-filled pipeline 9 penetrates through the through hole and is bonded with the through hole; the outer surface of the side wall of the plastic scintillator cylinder is plated with an aluminum film 7 with the thickness of 10 mu m; the inner surface is plated with an aluminum oxide film 6 with the thickness of 400 nm; the plastic scintillator cylinder is not coated with a film 8 on the side coupled with the photomultiplier.

The plastic scintillator wafer 11 with a film coated on the two sides, the plastic scintillator cylinder 12 and the gas-filled pipeline 9 are bonded by epoxy resin with good light transmittance, and the gas-filled pipeline 9 is connected with a valve 10 to form a hollow cylinder closed container. The uncoated side of the plastic scintillator cylinder is coupled with a photomultiplier 13 by silicone oil. Finally, the plastic scintillator and the photomultiplier are packaged by an aluminum shell 17, and the top of the aluminum shell is provided with a carbon fiber cover 16 with the thickness of 0.8 mm.

The plastic scintillator wafer and the outer surface of the plastic scintillator cylinder are plated with the aluminum film, so that the high-efficiency reflection of the fluorescence generated in the plastic scintillator into the photomultiplier is ensured, and the detection efficiency of beta rays is improved; the internal plating of the aluminum oxide film reduces the adsorption effect of xenon on the surface of the plastic scintillator, the plated film is very thin and only 400nm, the detection of beta rays is not influenced, and meanwhile, the plated film is made of transparent materials to ensure that fluorescence is collected by the photomultiplier; and the aluminum shell is used for packaging, and the bottom of the aluminum shell is made of carbon fiber, so that the absorption of low-energy X rays and gamma rays during coincidence measurement is reduced.

The vacuum-pumping test and the pressure-resistant test are carried out on the double-sided coated plastic scintillator detector, and the result shows that the detector can bear the pressure of 2.5 multiplied by 105Pa, the vacuum maintenance is better, and the sealing performance is good.

The double-sided coated plastic scintillator detector is filled^131mXe sample, placed on the HPGe detector, acquired a gamma spectrum 18, then repeatedly flushed through the plastic scintillator detector 3 times with nitrogen, and acquired a gamma spectrum 19, the gamma spectra before and after the nitrogen flush being shown in FIG. 4, from which it can be seen that substantially no visible spectrum is observed in the spectra after flushing with nitrogen^131mXe 164keV gamma ray peak, calculating the ratio of the counting rate of the energy spectrum peak after washing to the counting rate of the energy spectrum peak before washing to be 0.6 percent, namely the adsorption effect is 0.6 percent, and the adsorption effect of the uncoated plastic scintillator detector is about 5 percent.

The double-sided coated plastic scintillator detector is filled^131mXe sample, HPGe detector, double-coated plastic scintillator detector^131mThe electrons are converted in Xe and a gamma spectrum is acquired by the HPGe detector, and the measured raw gamma spectrum 20 and the coincidence gamma spectrum 21 are shown in fig. 5.^131mThe 129.4keV inner conversion electron of Xe has cascade coincidence relation with 29.8keV X-ray, and is calculated by the following formula^131mThe conversion electron detection efficiency in Xe 129.4keV was 99.8%.

In the formula, n_XIs the original spectrum X-ray peak count rate; n is_XcThe X-ray peak count rate of the coincidence spectrum.

The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, several modifications and variations can be made without departing from the technical principle of the present invention, and these modifications and variations should also be regarded as the protection scope of the present invention.