Passive electrostatic collection method radon measurement system based on CMOS image sensor

Abstract

The passive electrostatic collection method radon measurement system based on the CMOS image sensor comprises a measurement box, a measurement cover, a fixing screw, a rubber ring, a filter cover, a filter membrane, conductive silver adhesive, the CMOS image sensor, a first metal shielding layer, a second metal shielding layer, a high-voltage generation module, a CMOS peripheral circuit set and an upper computer. A plurality of holes are formed in the top of the measuring cover, the filter membranes are installed at the upper end and the lower end of the filter cover, the conductive silver adhesive is arranged in the measuring cover, the CMOS image sensor is installed outside the measuring box, the first metal shielding layer is not communicated with the conductive silver adhesive and is not communicated with a grounded second metal shielding layer on the surface of the CMOS image sensor, and the positive electrode of the high-voltage generating module is communicated with the conductive silver adhesive. The negative electrode is connected with the second metal shielding layer, and the upper computer is electrically connected with the CMOS image sensor, the high-voltage generation module and the CMOS peripheral circuit set. The conductive silver adhesive, the first metal shielding layer and the second metal shielding layer are adopted to control the direction of a high-voltage electrostatic field, the collection efficiency of positively charged Po-218 is enhanced, and the radon concentration measurement accuracy is further improved.

Description

Technical Field

[0001] The present invention relates to nuclear radiation detection technology, in particular to a passive electrostatic collection method radon measurement system based on a CMOS image sensor. Background Art

[0002] As an important radioactive gas in nature, radon is one of the main sources of human exposure to natural radiation. This colorless and odorless gas and its decay progeny are all radioactive elements. When people inhale air containing radon gas, these radioactive elements will produce internal irradiation in the human respiratory system, thus posing a potential threat to human health. Therefore, it is very important to study the measurement methods of radon and improve the measurement technology for radon radiation protection.

[0003] The electrostatic collection method is a common method for measuring radon. When measuring radon by the electrostatic collection method, a high-voltage electric field is set in the measurement cavity. Under the action of the electrostatic field, the radon that enters the measurement cavity decays to produce positively charged Po-218 progeny, which are adsorbed on the surface of the CMOS image sensor, and then continue to decay to produce progeny. Finally, the radon concentration is determined according to the number of particles collected by the CMOS image sensor. Among them, the design of the measurement cavity plays an extremely important role in the measurement efficiency. For example, the existing patent with the publication number CN113885068A discloses a method for jointly improving the electric potential distribution in the measurement cavity by using a CMOS image sensor and a metal mesh ring. However, the setting of the metal mesh ring and the calculation of the static voltage are relatively complex, which is not conducive to the rapid measurement of radon. Therefore, it is very important to realize the rapid and accurate measurement of radon by the electrostatic collection method of the CMOS image sensor. Summary of the Invention

[0004] The object of the present invention is to overcome the above deficiencies of the prior art and provide a passive electrostatic collection method radon measurement system based on a CMOS image sensor.

[0005] The technical solution of the present invention is: a passive electrostatic collection method radon measurement system based on a CMOS image sensor, including a measurement box, a measurement cover, fixing screws, rubber rings, filter covers, filter membranes, conductive silver glue, a CMOS image sensor, a first metal shielding layer, a second metal shielding layer, a high-voltage generating module, a CMOS peripheral circuit set, and a host computer.

[0006] The measurement box is a hollow box-shaped structure with a power interface provided on its side wall. The measurement cover is a hemispherical structure with multiple openings provided on its spherical top. Fixing screws are used to fix the measurement cover to the measurement box, and a rubber ring is provided at the connection between the measurement box and the measurement cover. The filter cover is a cylindrical structure with openings at both ends. The bottom opening of the filter cover is fixed to the measurement cover and its opening corresponds to the openings on the measurement cover. Filter membranes are respectively fixed and installed on the bottom opening and the top opening of the filter cover. Conductive silver paste is provided on the inner part of the measurement cover. A CMOS image sensor is installed at the central position on the outer wall of the measurement box. A first metal shielding layer is provided on the outer wall of the measurement box and is located at the bottom of the measurement cover. A second metal shielding layer covers the CMOS image sensor. The first metal shielding layer is not connected to the conductive silver paste coated inside the measurement cover, nor is it connected to the second metal shielding layer that is grounded on the surface of the CMOS image sensor. The high-voltage generating module is used to generate high voltage, its positive electrode is connected to the conductive silver paste coated inside the measurement cover, and its negative electrode is connected to the second metal shielding layer. The CMOS peripheral circuit assembly is electrically connected to the CMOS image sensor. Both the high-voltage generating module and the CMOS peripheral circuit assembly are placed inside the measurement box.

[0007] The host computer is electrically connected to the CMOS image sensor, the high-voltage generating module, and the CMOS peripheral circuit assembly. It is internally provided with a module for processing the high-energy β and γ rays generated by the subsequent decay of Po-218 recorded by the CMOS image sensor to obtain the radon concentration, and a module for supplying power to the high-voltage generating module and the CMOS peripheral circuit assembly.

[0008] A further technical solution of the present invention is that the materials of the measurement box and the measurement cover are both plastics.

[0009] A further technical solution of the present invention is that the materials of the first metal shielding layer and the second metal shielding layer are selected as aluminum films with a thickness of 0.1 - 100 microns.

[0010] A further technical solution of the present invention is that the material of the filter membrane is a glass fiber filter membrane or quartz fiber.

[0011] Compared with the prior art, the present invention has the following characteristics: The passive electrostatic collection method radon measurement system provided by the present invention has a simple structure and is convenient to carry. By using conductive silver paste and the metal shielding layer on the outer wall of the measurement box, the high-voltage electrostatic field only points to the metal shielding layer grounded on the surface of the CMOS image sensor, improving the collection efficiency of positively charged Po-218, and thus improving the accuracy of radon concentration measurement.

[0012] The detailed structure of the present invention will be further described below in conjunction with the drawings and specific embodiments. Description of the Drawings

[0013] Figure 1 It is a schematic structural diagram of the passive electrostatic collection method radon measurement system of the present invention; Figure 2 is Figure 1 a cross-sectional view; Figure 3 is Figure 2 a partially enlarged view of I in; Figure 4 is Figure 2 a partially enlarged view of II in. Specific Embodiments

[0014] Embodiment 1, as Figures 1-4 shown, a passive electrostatic collection method radon measurement system based on a CMOS image sensor, including a measurement box 1, a measurement cover 2, fixing screws 3, rubber rings 4, a filter cover 5, a filter membrane 6, conductive silver paste 7, a CMOS image sensor 8, a first metal shielding layer 9-1, a second metal shielding layer 9-2, a high-voltage generation module 10, a CMOS peripheral circuit set 11, and a host computer 12 (not shown in the figure).

[0015] The measurement box 1 is a hollow box shape, and a power interface 1-1 is provided on its side wall. The measurement cover 2 is a hemispherical structure, and a plurality of openings 2-1 are provided at its spherical top. The fixing screws 3 are used to fix the measurement cover 2 to the measurement box 1. The rubber ring 4 is arranged at the connection between the measurement box 1 and the measurement cover 2 so that there is a gap between the measurement box 1 and the measurement cover 2. The materials of the measurement box 1 and the measurement cover 2 are both plastics. The filter cover 5 is a cylindrical structure with openings at both ends. The bottom opening of the filter cover 5 is fixed to the measurement cover 2 and corresponds to the opening 2-1 of the measurement cover 2. Thus, when the radon-containing air enters from the top opening of the filter cover 5, it can enter the measurement cover 2 through the bottom opening and the opening 2-1 of the measurement cover 2. The filter membrane 6 is respectively fixedly installed on the bottom opening and the top opening of the filter cover 5, and is used to filter most of the impurities in the air, such as particulate matters such as dust and aerosol, to avoid carrying radon daughters, etc., and can also be used to make Rn-220 with a half-life of 55.6 seconds basically decay and not enter the measurement cover, so as to improve the accuracy of radon measurement. The material of the filter membrane is selected as glass fiber filter membrane, quartz fiber, etc. The conductive silver paste 7 is arranged inside the measurement cover 2 and is used for electrical connection with the high-voltage generation module 10 to form a high-voltage electrostatic field inside the measurement cover 2.

[0016] The CMOS image sensor 8 is installed at the central position of the outer wall of the measurement box 1 and is used to record the high-energy β and γ rays generated by the subsequent decay of Po-218 under the action of the high-voltage electrostatic field.

[0017] The first metal shielding layer 9-1 is arranged on the outer wall of the measurement box 1 and is located at the bottom of the measurement cover 2. The second metal shielding layer 9-2 covers the CMOS image sensor 8. The structures of the first metal shielding layer 9-1 and the second metal shielding layer 9-2 are the same, and their thickness is 0.1 to 100 microns. The material is selected as an aluminum film or other metal films. AsFigure 3 and Figure 4 As can be seen from the enlarged partial view shown in Figure 4 , the first metal shielding layer 9-1 is not connected to the conductive silver paste 7 coated inside the measurement cover 2, nor is it connected to the second metal shielding layer 9-2 grounded on the surface of the CMOS image sensor 8.

[0018] The high-voltage generating module 10 is used to generate a high voltage of 2000V. Its positive electrode is connected to the conductive silver paste 7 coated inside the measurement cover 2, and its negative electrode is connected to the second metal shielding layer 9-2. The CMOS peripheral circuit set 11 is electrically connected to the CMOS image sensor 8 and is used to drive the CMOS image sensor 8. Both the high-voltage generating module 10 and the CMOS peripheral circuit set 11 are placed inside the measurement box 1 to reduce the occupied space of the system and improve portability.

[0019] The host computer 12 is electrically connected to the CMOS image sensor 8, the high-voltage generating module 10, and the CMOS peripheral circuit set 11. It is internally provided with a module for processing the high-energy β and γ rays generated by the subsequent decay of Po-218 recorded by the CMOS image sensor 8 to obtain the radon concentration, and a module for providing power to the high-voltage generating module 10 and the CMOS peripheral circuit set 11, etc.

[0020] The radon-containing air to be measured enters the filter cover 5 through the filter membrane 6, and then enters the measurement cover 2 through the openings 2-1 on the filter membrane 6 and the measurement cover 2. Some impurities and Rn-220 that affect the measurement accuracy are further filtered out by the two-layer filter membrane 6 of the filter cover 5, and the radon-containing air to be measured is more uniform through the action of the filter cover 5. Start the high-voltage generating module 10 to form a high-voltage electrostatic field between the inside of the measurement cover 2 and the second metal shielding layer 9-2. The radon in the radon-containing air to be measured in the measurement cover 2 decays in the measurement cover 2. First, radon decays to produce positively charged Po-218. The positively charged Po-218 is collected by the electrostatic field on the second metal shielding layer 9-2 grounded on the surface of the CMOS image sensor 8. The subsequent emitted β and γ rays will enter the CMOS image sensor 8 to produce bright spots. The bright spots generated are counted through the CMOS peripheral circuit set 11 and the host computer 12, and the radon concentration in the radon-containing air to be measured is inversely deduced.

[0021] Since the first metal shielding layer 9-1 around the CMOS image sensor 8 in the measurement cover 2 can shield the influence generated by the CMOS peripheral circuit set 11 below it, the high-voltage electrostatic field only points to the second metal shielding layer 9-2 grounded on the surface of the CMOS image sensor 8, greatly improving the collection efficiency of positively charged Po-218, reducing the statistical fluctuation error, and improving the accuracy of the measured radon concentration value.

Claims

1. A radon measurement system based on a passive electrostatic collection method using a CMOS image sensor, characterized in that: It includes a measurement box, a measurement cover, fixing screws, rubber rings, a filter cover, a filter membrane, conductive silver paste, a CMOS image sensor, a first metal shielding layer, a second metal shielding layer, a high-voltage generating module, a CMOS peripheral circuit set, and a host computer; The measurement box is a hollow box-shaped structure with a power interface provided on its side wall. The measurement cover is a hemispherical structure with multiple openings provided at its spherical top. The fixing screws are used to fix the measurement cover to the measurement box, and the rubber rings are provided at the connection between the measurement box and the measurement cover. The filter cover is a tubular structure with openings at both ends. The bottom opening of the filter cover is fixed to the measurement cover and its opening corresponds to the openings of the measurement cover. The filter membrane is respectively fixed to the bottom opening and the top opening of the filter cover. The conductive silver paste is provided on the inner part of the measurement cover. The CMOS image sensor is installed at the central position of the outer wall of the measurement box. The first metal shielding layer is provided on the outer wall of the measurement box and is located at the bottom of the measurement cover. The second metal shielding layer covers the CMOS image sensor. The first metal shielding layer is not connected to the conductive silver paste coated inside the measurement cover, nor is it connected to the second metal shielding layer grounded on the surface of the CMOS image sensor. The high-voltage generating module is used to generate high voltage, its positive electrode is connected to the conductive silver paste coated inside the measurement cover, and the negative electrode is connected to the second metal shielding layer. The CMOS peripheral circuit set is electrically connected to the CMOS image sensor. Both the high-voltage generating module and the CMOS peripheral circuit set are placed inside the measurement box; The host computer is electrically connected to the CMOS image sensor, the high-voltage generating module, and the CMOS peripheral circuit set. It is internally provided with a module for processing the high-energy β and γ rays generated by the subsequent decay of Po-218 recorded by the CMOS image sensor to obtain the radon concentration, and a module for supplying power to the high-voltage generating module and the CMOS peripheral circuit set.

2. The radon measurement system based on the passive electrostatic collection method using a CMOS image sensor according to claim 1, characterized in that: The materials of the measurement box and the measurement cover are both plastics.

3. The radon measurement system based on the passive electrostatic collection method using a CMOS image sensor according to claim 1, characterized in that: The materials of the first metal shielding layer and the second metal shielding layer are selected as aluminum films with a thickness of 0.1 - 100 microns.

4. The radon measurement system based on the passive electrostatic collection method using a CMOS image sensor according to claim 1, characterized in that: The material of the filter membrane is a glass fiber filter membrane or quartz fiber.

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