Device and method for measuring scale coefficient of emanometer in high vacuum environment

Abstract

The invention discloses a device and a method for measuring a scale coefficient of a radon measuring instrument in a high-vacuum environment. The device comprises a measuring box, a scintillation chamber, a solid radon source, the radon measuring instrument, a scintillation chamber measuring assembly, a controller and a filter membrane. The measuring box and the scintillation chamber are vacuumized sealing boxes, the scintillation chamber is provided with an air inlet with a remote control valve, a filter membrane is arranged at the air inlet, the solid radon source is placed at the bottom of the measuring box, the scintillation chamber measuring assembly is located at the bottom of the scintillation chamber, and the controller is located outside the measuring box and controls the valve at the air inlet of the scintillation chamber to be opened or closed in a wireless mode. And when the scale coefficient is measured, vacuumizing and opening the valve are carried out, the valve is closed when the radon concentration is balanced, standing counting is carried out, the radon concentration is calculated, corresponding particle counting is selected according to the measured energy spectrum, and then the scale coefficient of the radon measuring instrument is calculated. The device is simple in structure, convenient to operate and easy to control, and can be suitable for solving the scale coefficient of the radon concentration measuring instrument in the high-vacuum environment such as the moon or the Mars.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of radon measuring instrument calibration coefficient measurement, and particularly relates to a radon measuring instrument calibration coefficient measurement device and method in a high vacuum environment. BACKGROUND

[0002] As a radioactive gas produced by radium-226 decay, radon concentration measurement is very important for environmental safety. Most of the commonly used radon measuring devices need to use radon measuring instruments. For conventional radon measurement in the environment, high-precision RAD7 measuring instruments can be used to achieve the measurement, but when it is necessary to measure the radon concentration in a high vacuum environment, such as the moon or other extreme environments, the measuring instruments are only suitable for an atmospheric pressure environment on the earth's surface, and it is difficult to obtain accurate radon concentration in a high vacuum environment such as the moon. Therefore, it is necessary to accurately measure the radon measuring instrument calibration coefficient in a high vacuum environment.

[0003] The China-France radon measurement instrument cooperation team of the Chang'e-6 mission successfully completed the radon detection task, and the radon measurement instrument that has completed the mission has become a "permanent resident" on the back of the moon. The radon measurement instrument uses a silicon-based detector to measure the ionizing radiation on the moon's surface, and the main detection target is the alpha particles emitted by Rn-222 and Rn-220 isotopes and their decay products in the lunar soil, aiming to study the origin and dynamics of the very thin lunar atmosphere, the thermal and physical properties of the lunar soil, and the migration of surface dust. The radium decay in the lunar soil is the same as that in the earth's soil, and only part of the radon produced by the decay can enter the lunar soil pores and then be transported to the lunar surface environment through the soil pores. The radon calibration coefficient of the radon measuring instrument using the electrostatic collection method on the earth's surface changes in a vacuum environment such as the moon, so it is difficult to obtain the real radon concentration in a high vacuum environment such as the moon. Therefore, it is necessary to design a suitable device and method to obtain the radon measuring instrument calibration coefficient in a high vacuum environment such as the moon. SUMMARY

[0004] The purpose of the present application is to overcome the above-mentioned deficiencies of the prior art and provide a radon measuring instrument calibration coefficient measurement device and method in a high vacuum environment.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical solution: a radon measuring instrument calibration coefficient measurement device in a high vacuum environment, comprising a measurement box, a scintillation chamber, a solid radon source, a radon measuring instrument, a scintillation chamber measurement assembly, a controller and a filter membrane.

[0006] The measuring box is a sealed box with vacuum, the scintillation chamber is a vacuum chamber, and has a closed air inlet, the outlet of the air inlet is provided with a sealing element, the sealing element is opened or closed by remote control, and a filter membrane is arranged at the air inlet; the solid radon source is placed at the bottom of the measuring box, the radon released by the solid radon source accumulates in the measuring box, the scintillation chamber measuring assembly is located at the bottom of the scintillation chamber, the scintillation chamber is measured and counted, and the controller is located outside the measuring box and controls the sealing element at the air inlet of the scintillation chamber to be opened or closed in a wireless mode.

[0007] Further technical solutions of the present application are that the measuring box is provided with a mechanical pump and a molecular pump to vacuumize the measuring box, when the high-vacuum environment is the moon, the air pressure value of the measuring box is set to 10 -7 Pa~10 -10 Pa, when the high-vacuum environment is Mars, the air pressure value of the measuring box is set to 10 -6 Pa~10 -8 Pa.

[0008] Still further technical solutions of the present application are that the sealing element is selected as an electric valve which is remotely opened or closed.

[0009] Still further technical solutions of the present application are that the material of the measuring box is selected as a high-strength material.

[0010] Another technical solution provided by the present application is a method applied to the radon meter calibration coefficient measuring device in the high-vacuum environment, comprising the following steps, I. The air pressure value in the measuring box is vacuumized to the air pressure value in the high-vacuum environment to be simulated, the solid radon source is placed in the measuring box for 14 days, then the radon meter is started and the concentration value of radon and its daughter measured by the radon meter is recorded; meanwhile, the controller controls the sealing element at the air inlet of the scintillation chamber to be in an open state in a wireless remote control mode, the radon-containing gas in the measuring box rapidly diffuses, enters the scintillation chamber through the filter membrane at the air inlet of the scintillation chamber, and is placed for 1-12 hours, when the radon concentration in the scintillation chamber reaches the balance with the radon concentration in the measuring box, the controller controls the sealing element at the air inlet of the scintillation chamber to be in a closed state.

[0011] II. The scintillation chamber in the balanced state is placed for 3 hours, at this time, the radon concentration in the scintillation chamber is still equal to that in the measuring box, the scintillation chamber measuring assembly is started to count the scintillation chamber, and the decay counting rate of radon and its daughter in the scintillation chamber is recorded as N 1 On this basis, the calculation expression of the radon concentration in the scintillation chamber is: C Rn =A*N 1 (1) Among them, CRn The radon concentration in the scintillation chamber is measured in Bq / m³. 3 Since the concentration of radon gas in the measuring chamber is the same as that in the scintillation chamber, this value is equal to the value of the radon detector. A The calibration factor for radon was measured under the high vacuum environment inside the chamber.

[0012] III. The energy spectrum of radon and its decay products was obtained by measuring the radon spectrum in the radon detector. The alpha particle count corresponding to the energy spectrum of 5.5 MeV produced by the decay of Rn-222 was selected and denoted as [missing information]. N 2 Then the calibration coefficient B of the radon meter is (A*N 1 ) / N 2 .

[0013] A further technical solution of the present invention is: to count the total number of alpha particles emitted by the decay of Rn-222 and Po-214, and record them as follows: N 3 Then the calibration coefficient B of the radon meter is (A*N 1 ) / N 3 .

[0014] Compared with the prior art, the present invention has the following characteristics: The device of this invention is simpler in structure, easier to operate, and easier to control compared to existing electrostatic collection methods. The method of this invention can be used to determine the calibration coefficient of radon in a high-vacuum environment, and is applicable to solving the calibration coefficient of radon concentration measuring instruments in high-vacuum environments such as the moon or Mars.

[0015] The detailed structure of the present invention will be further described below with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of the measuring device for the calibration coefficient of a radon detector under high vacuum conditions. Detailed Implementation

[0017] Example 1, as Figure 1 As shown, the measuring device for the calibration coefficient of a radon detector under high vacuum includes a measuring box 1, a scintillation chamber 2, a solid radon source 3, a radon detector 4, a scintillation chamber measuring component 5, a controller 6, and a filter membrane 7.

[0018] The measuring chamber 1 is a sealed chamber. A mechanical pump and a molecular pump are used to evacuate the interior of the measuring chamber 1 to simulate a high-vacuum environment. For example, when simulating the high-vacuum environment on the moon, the pressure is set to 10. -7 Pa~10 -10Pa; when simulating the high vacuum environment on Mars, the gas pressure value is set to 10 -6 Pa~10 -8 Pa. The scintillation chamber 2 is a vacuum chamber, and has a sealed air inlet 2-1, and a sealing element (not shown in the figure) is arranged at the outlet of the air inlet 2-1, which can be opened or closed by remote control, and is usually selected as an electric valve that can be remotely opened or closed. A filter membrane 7 is arranged at the air inlet 2-1. The solid radon source 3 is placed at the bottom of the measuring box 1, and the radon released by the solid radon source 3 accumulates in the measuring box 1, and the radon concentration increases over time and reaches a steady state after about 14 days. The scintillation chamber measuring assembly 5 is located at the bottom of the scintillation chamber 2, and can measure the scintillation chamber 2. The components and counting methods of the measurement count are known in the art, such as counting by a photomultiplier tube and a scaler, and will not be described in detail here. The controller 6 is located outside the measuring box 1, and controls the opening or closing of the electric valve at the air inlet 2-1 of the scintillation chamber 2 in a wireless manner.

[0019] According to actual needs, the material of the measuring box 1 is selected to be steel or other materials with high strength to improve the safety of the measurement.

[0020] Embodiment two, the method applied to the embodiment one high vacuum environment radon measuring instrument calibration coefficient measuring device, comprising the following steps: The gas pressure value in the measuring box 1 is vacuumed to the gas pressure value in the high vacuum environment to be simulated. When simulating the high vacuum environment on the moon, the gas pressure value is set to 10-7 Pa~10-10 Pa; when simulating the high vacuum environment on Mars, the gas pressure value is set to 10-6 Pa~10-8 Pa. After the solid radon source 3 is placed in the measuring box 1 for 14 days, the radon measuring instrument 4 is started and the concentration value of radon and its daughter measured by the radon measuring instrument 4 is recorded. At the same time, the controller 6 controls the sealing element at the air inlet 2-1 of the scintillation chamber 2 to be in an open state in a wireless remote control manner, the radon-containing gas in the measuring box 1 rapidly diffuses, enters the scintillation chamber 2 through the filter membrane 7 at the air inlet 2-1 of the scintillation chamber 2, and is placed for 1~12 hours. When the radon concentration in the scintillation chamber 2 reaches equilibrium with the radon concentration in the measuring box 1, the controller 6 controls the sealing element at the air inlet 2-1 of the scintillation chamber 2 to be in a closed state.

[0021] The scintillation chamber 2 in the equilibrium state is placed for 3 hours, at which time the radon concentration in the scintillation chamber 2 is still equal to that in the measuring box 1. The scintillation chamber measuring assembly 5 is started to count the scintillation chamber 2, and the decay counting rate of radon and its daughter in the scintillation chamber 2 is recorded as N 1 On this basis, the calculation expression of the radon concentration in the scintillation chamber 2 is obtained as: C Rn =A*N 1 (1) Wherein, C Rn The radon concentration in the scintillation chamber 2, i.e. the radon concentration in the measuring box 1, is in units of Bq / m 3 Since the radon-containing gas in the measuring box 1 has the same radon concentration as the radon-containing gas in the scintillation chamber 2, the value is equal to the value of the radon measuring instrument 4; A The calibration factor of radon in the high-vacuum environment in the measuring box 1.

[0022] The energy spectrum of radon and its daughter nuclei in the radon measuring instrument 4 is measured. Since the energy of the alpha particles emitted by Rn-222, Rn-220 and their daughter nuclei decays differs by more than 0.5 MeV, the probability of peak overlap in the energy spectrum is small, so the energy discrimination of the alpha particles can exclude the interference of other nuclides. According to the energy of the alpha particles released by the alpha decay of radon and its daughter nuclei, the half-life of Rn-222 is 3.8 days and the corresponding alpha particle energy is 5.5 MeV, so the alpha particle count corresponding to the energy spectrum of 5.5 MeV generated by the decay of Rn-222 is selected as N 2 The calibration coefficient B of the radon measuring instrument 4 is A*N 1 N 2 .

[0023] In order to further reduce the error caused by statistical fluctuations, the total number of alpha particles emitted by the decay of Rn-222 and Po-214 is counted as N 3 The calibration coefficient B of the radon measuring instrument 4 is A*N 1 N 3 .

[0024] The above implementation cases reflect the application level and occasion of the content of the application, and any technical solution that achieves the same purpose by the same means is within the scope of protection of the application.​​

Claims

1. A device for measuring the calibration coefficient of a radon measuring instrument in a high vacuum environment, characterized in that it comprises: The utility model relates to a radon measurement device, including measurement box, scintillation chamber, solid radon source, radon measurement instrument, scintillation chamber measurement assembly, controller and filter membrane; The measurement box is a sealed box that is evacuated, the scintillation chamber is an evacuated chamber, and has a sealed air inlet, a seal is provided at the outlet of the air inlet, the seal is opened or closed by remote control, and a filter membrane is provided at the air inlet; the solid radon source is placed at the bottom of the measurement box, radon released by the solid radon source accumulates in the measurement box, the scintillation chamber measurement assembly is located at the bottom of the scintillation chamber, the scintillation chamber is measured and counted, and the controller is located outside the measurement box and controls the seal at the air inlet of the scintillation chamber to be opened or closed wirelessly.

2. The device for measuring the calibration coefficient of a radon measurement instrument in a high vacuum environment according to claim 1, characterized in that: The measuring box adopts a mechanical pump and a molecular pump to vacuumize the measuring box, and when the high-vacuum environment is the moon, the air pressure value of vacuumizing the measuring box is set to 10 -7 Pa~10 -10 Pa; when the high-vacuum environment is Mars, the air pressure value of vacuumizing the measuring box is set to 10 -6 Pa~10 -8 Pa.

3. The device for measuring the calibration coefficient of a radon measurement instrument in a high vacuum environment according to claim 1, characterized in that: The seal is selected to be an electric valve that is remotely opened or closed.

4. The device for measuring the calibration coefficient of a radon measurement instrument in a high vacuum environment according to claim 1, characterized in that: The material of the measurement box is selected to be a high-strength material.

5. The method for measuring the calibration coefficient of the radon measurement device in high vacuum environment according to any one of claims 1-4, characterized in that: The utility model relates to a radon measurement device, including the following steps, I. the air pressure value in the measurement box is evacuated to the air pressure value under the high-vacuum environment to be simulated, the solid radon source is placed in the measurement box for 14 days, the radon measurement instrument is started, and the concentration value of radon and its daughter bodies measured by the radon measurement instrument is recorded; at the same time, the controller controls the seal at the air inlet of the scintillation chamber to be in an open state by wireless remote control, the radon-containing gas in the measurement box rapidly diffuses, enters the scintillation chamber through the filter membrane at the air inlet of the scintillation chamber, is placed for 1-12 hours, and when the radon concentration in the scintillation chamber and the radon concentration in the measurement box reach equilibrium, the controller controls the seal at the air inlet of the scintillation chamber to be in a closed state; II. The scintillation chamber in equilibrium state is kept for 3 hours, at this time the radon concentration in the scintillation chamber is still equal to that in the measuring box, the scintillation chamber measurement assembly is started to count the scintillation chamber, and the decay counting rate of radon and its daughter bodies in the scintillation chamber is obtained, denoted as N 1 On this basis, the calculation expression of the radon concentration in the scintillation chamber is obtained as follows: C Rn A*N 1 （1） wherein, C Rn R is the radon concentration in the scintillation chamber, i.e. the measurement chamber, in Bq / m 3 Since the radon-containing gas in the measurement chamber has the same radon concentration as the radon-containing gas in the scintillation chamber, this value is equal to the value of the radon meter; A is the calibration factor for radon in the high vacuum environment in the measurement chamber. III. The energy spectrum of radon and its daughter bodies in the radon measuring instrument is measured, and the α particle count corresponding to the energy spectrum of 5.5 MeV generated by the decay of Rn-222 measured by the radon measuring instrument is selected as N 2 The calibration coefficient B of the radon measuring instrument is (A*N 1 ) / N 2 .

6. The method for measuring the calibration coefficient of a radon measurement instrument in a high vacuum environment according to claim 5, characterized in that: The total number of α particles emitted by the decay of Rn-222 and Po-214 is counted as N 3 The calibration coefficient B of the radon meter is (A* N 1 ) / N 3 .

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