Device and method for measuring emanation coefficient of radon generated by radium decay in lunar soil

Abstract

The invention discloses a device and a method for measuring the emanation coefficient of radon generated by radium decay in lunar soil. The device comprises a nitrogen cylinder, a pressure reducing valve, a first connector, a first electromagnetic valve, a metal container, a pressure gauge, a second electromagnetic valve, a second connector and an air pump. The nitrogen cylinder, the pressure reducing valve, the first connector, the first electromagnetic valve, the metal container, the second electromagnetic valve, the second connector and the air pump are sequentially connected in series, and the other end of the air pump is communicated with the external environment. The method comprises the following steps: starting an air pump to control the air pressure value of a metal container, respectively recording the radon activity of lunar soil particles in the metal container at present and after 28 days, establishing a relational expression between the radon emanation coefficient and the radon activity of the lunar soil particles under different air pressures, substituting the measured radon activity into the relational expression, and fitting to obtain a relation curve between the emanation coefficient and the air pressure. And substituting the air pressure value on the moon to calculate the emanation coefficient of the lunar soil at the normal temperature. The measuring device is simple, the measuring process is convenient and fast, and the emanation coefficient of radon generated by radium decay in lunar soil in the atmosphere-free environment such as the moon and the like can be obtained.

Description

Technical Field

[0001] This invention relates to the field of radon emission coefficient measurement, and in particular to a device and method for measuring the radon emission coefficient generated by radium decay in lunar soil. Background Technology

[0002] Radon, a radioactive gas produced by the decay of radium-226, has an emissivity coefficient that is a key parameter for assessing the lunar surface radiation environment, lunar soil gas migration characteristics, and in-situ resource utilization, such as radon as a tracer. It is of great significance for studying Earth's early history and the origin and evolution of the solar system. Due to the lack of an atmosphere on the Moon, radon's diffusion behavior differs significantly from that on Earth, and its emissivity directly affects the estimation of lunar surface radiation dose and the gas safety of sealed compartments. The Chang'e lunar exploration program, through collecting lunar samples and conducting in-situ exploration, has provided scientists with valuable research data, promoting the development of lunar science and even planetary science as a whole.

[0003] The Sino-French radon measurement instrument team, jointly formed by the Institute of Geology and Geophysics, Chinese Academy of Sciences, and its French counterparts, successfully completed its radon detection mission on the Chang'e 6 lunar probe. The instrument, now a "permanent resident" of the far side of the moon, uses a silicon-based detector to measure ionizing radiation on the lunar surface. Its primary target is alpha particles emitted from the Rn-222 and Rn-220 isotopes and their decay products in the lunar regolith. The aim is to study the origin and dynamics of the very thin lunar atmosphere, the thermal and physical properties of the lunar regolith, and the transport of surface dust. Only a portion of the radon produced by the decay of radium in the lunar regolith can enter the pores. The ratio of the number of radon atoms released to the number produced from radium-containing particles is called the egress coefficient. Compared to Earth's soil, the extreme low-pressure conditions on the moon may significantly alter the egress coefficient of radon produced by radium decay in the lunar regolith, thus requiring further measurements to determine the actual egress coefficient. Summary of the Invention

[0004] The purpose of this invention is to overcome the above-mentioned shortcomings of the prior art and provide a device and method for measuring the emission coefficient of radon generated by radium decay in lunar soil.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a device for measuring the emission coefficient of radon generated by radium decay in lunar soil, comprising a nitrogen cylinder, a pressure reducing valve, a first connector, a first solenoid valve, a metal container, a pressure gauge, a second solenoid valve, a second connector, and a gas pump.

[0006] The nitrogen cylinder contains high-purity nitrogen. A pressure gauge is installed on the upper part of the metal container. The outlet of the nitrogen cylinder is connected to the inlet of the pressure reducing valve. The outlet of the pressure reducing valve is connected to the inlet of the first connector. The outlet of the first connector is connected to the inlet of the first solenoid valve. The outlet of the first solenoid valve is connected to the inlet of the metal container. The outlet of the metal container is connected to the inlet of the second solenoid valve. The outlet of the second solenoid valve is connected to the inlet of the second connector. The outlet of the second connector is connected to one end of the air pump. The other end of the air pump is connected to the external environment.

[0007] A further technical solution of the present invention is that the first connector and the second connector enable the metal container to be detachably connected.

[0008] A further technical solution of the present invention is: lunar soil is placed in a mug that is standardly used with a sodium iodide gamma spectrometer, and the mug is placed together with the lunar soil in a metal container.

[0009] A further technical solution of the present invention is that the material of the metal container is steel.

[0010] Another technical solution of the present invention is: a method for measuring the radon emission coefficient generated by radium decay in lunar soil, comprising the following steps, 1. Seal the lunar soil to be tested in a metal container. Connect the metal container to the pressure reducing valve and the air pump via the first and second connectors. Control the opening of the pressure reducing valve, the first solenoid valve, and the second solenoid valve. Start the air pump and adjust its flow rate. Observe the air pressure value inside the metal container measured by the pressure gauge in real time. Adjust the air pressure value inside the metal container to a pressure of [insert pressure value here]. P i The air pressure P i To simulate the pressure of a high-vacuum environment and maintain it for more than 6 hours; then, the pressure reducing valve, the first solenoid valve, and the second solenoid valve were closed, and the first connector and the second connector were disconnected. The metal container was placed in the lead chamber for measurement, and the radon activity in the lunar soil particles was recorded as follows. A Pi-Rn1 .

[0011] 2. After placing the metal container and the lunar soil inside for 28 days, repeat step one to adjust the air pressure inside the metal container to a pressure of [insert pressure here]. P i The radon activity in lunar soil particles was measured and recorded as follows, and maintained for at least 6 hours. A Pi-Rn2 .

[0012] III. A one-to-one correspondence was used to record the radon activity in multiple groups of lunar soil particles, denoted as... A Pi-Rn1 The radon activity in lunar soil particles measured again after 28 days is recorded as follows:A Pi-Rn2 Substituting the obtained data into the following radon emission coefficients under different air pressures... k Pi Calculation formula: (1) The measured radon activity was substituted into the formula for fitting to obtain the relationship curve between the gas ejection coefficient and the air pressure. The air pressure value on the moon was then substituted into the fitted relationship curve between the gas ejection coefficient and the air pressure to obtain the predicted value of the gas ejection coefficient of the lunar surface soil at normal temperature.

[0013] A further technical solution of the present invention is that the gas pressure value inside the metal container is a series of gas pressures lower than one atmosphere.

[0014] Compared with the prior art, the present invention has the following characteristics: This invention controls the air pressure in a metal container by setting and activating an air pump, recording the radon activity of lunar soil particles in the container both currently and 28 days later. The measured radon activity is then substituted into a formula to fit the relationship between the gas ejection coefficient and air pressure, and finally, the gas ejection coefficient of the lunar soil at room temperature is calculated by substituting the lunar air pressure value. This invention features a simple measuring device and a convenient measurement process, enabling the determination of the gas ejection coefficient of radon produced by radium decay in lunar soil, which lacks an atmosphere, such as on the moon.

[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 A schematic diagram of the device for measuring the emission coefficient of radon produced by the decay of radium in lunar soil. Detailed Implementation

[0017] Example 1, as Figure 1 As shown, the device for measuring the radon emission coefficient generated by radium decay in lunar soil includes a nitrogen cylinder 1, a pressure reducing valve 2, a first connector 3, a first solenoid valve 4, a metal container 5, a pressure gauge 6, a second solenoid valve 7, a second connector 8, and a gas pump 9.

[0018] The nitrogen cylinder 1 contains high-purity nitrogen gas. A pressure gauge 6 is installed on the upper part of the metal container 5 to measure the gas pressure inside the metal container 5. The outlet of the nitrogen cylinder 1 is connected to the inlet of the pressure reducing valve 2. The outlet of the pressure reducing valve 2 is connected to the inlet of the first connector 3. The outlet of the first connector 3 is connected to the inlet of the first solenoid valve 4. The outlet of the first solenoid valve 4 is connected to the inlet of the metal container 5. The outlet of the metal container 5 is connected to the inlet of the second solenoid valve 7. The outlet of the second solenoid valve 7 is connected to the inlet of the second connector 8. The outlet of the second connector 8 is connected to one end of the air pump 9, and the other end of the air pump 9 is connected to the external environment. The first connector 3 and the second connector 8 make the metal container 5 detachably connected.

[0019] To reduce background radiation interference during measurement and ensure that the detector captures only the gamma rays from the lunar soil itself, thereby improving detector efficiency, the lunar soil to be measured is placed in a mug that is standard with the sodium iodide gamma spectrometer. The mug, along with the lunar soil, is then placed into metal container 5. Using gas pump 9, nitrogen gas from nitrogen cylinder 1 is drawn into metal container 5, and the pressure value in metal container 5 is monitored in real time by pressure gauge 6.

[0020] Depending on the actual needs, the metal container 5 may be made of steel or other robust materials to improve the safety of measurements under low pressure.

[0021] Example 2, a method for measuring the radon emission coefficient generated by radium decay in lunar soil in Example 1, includes the following steps: The lunar soil to be tested is sealed inside a metal container 5. The metal container 5 is connected to a pressure reducing valve 2 and an air pump 9 via a first connector 3 and a second connector 8. The pressure reducing valve 2, the first solenoid valve 4, and the second solenoid valve 7 are opened. The air pump 9 is started, and its flow rate is adjusted. The air pressure value inside the metal container 5, measured by the pressure gauge 6, is observed in real time. The air pressure value inside the metal container 5 is then adjusted to a pressure of [insert pressure value here]. P i The air pressure setting value P i A series of atmospheric pressure values, such as 0.8, 0.7, 0.6, 0.5...0.1, 0.08 atmospheres, were set to simulate a high vacuum environment and maintained for more than 6 hours. Then, pressure reducing valve 2, first solenoid valve 4, and second solenoid valve 7 were closed, and first connector 3 and second connector 8 were disconnected. The metal container 5 was placed in the lead chamber for measurement, and the radon activity in the lunar soil particles was recorded as... A Pi-Rn1 .

[0022] Since only a portion of the radon produced by the decay of radium in lunar soil can enter the pores of lunar soil, it takes about 6 hours for Bi-214 on the surface of lunar soil particles to decay completely. That is, under normal atmospheric pressure, after the lunar soil is purged with nitrogen for 6 hours, the radon in its internal pores is carried out, and the radon and Bi-214 in the lunar soil particles reach equilibrium.

[0023] After placing the metal container 5 and the lunar soil inside for 28 days, repeat step one to adjust the air pressure inside the metal container 5 to a pressure of [insert pressure here]. P i The radon activity in lunar soil particles was measured and recorded as follows, and maintained for at least 6 hours. A Pi-Rn2 .

[0024] The radon activity in multiple sets of lunar soil particles was recorded in a one-to-one correspondence. A Pi-Rn1 The radon activity in lunar soil particles measured again after 28 days is recorded as follows: A Pi-Rn2 Substituting the obtained data into the following radon emission coefficients under different air pressures... k Pi Calculation formula: (1) The measured radon activity was substituted into the formula for fitting to obtain the relationship curve between the gas ejection coefficient and the air pressure. The air pressure value on the moon was then substituted into the fitted relationship curve between the gas ejection coefficient and the air pressure to obtain the predicted value of the gas ejection coefficient of the lunar surface soil at normal temperature.

[0025] The above implementation examples reflect the application levels and occasions of the present invention. Any technical solution that achieves the purpose of the present invention by essentially the same means falls within the protection scope of the present invention.

Claims

1. A device for measuring the emission coefficient of radon produced by radium decay in lunar soil, characterized by: Includes a nitrogen cylinder, a pressure reducing valve, a first connector, a first solenoid valve, a metal container, a pressure gauge, a second solenoid valve, a second connector, and a gas pump; The nitrogen cylinder contains high-purity nitrogen. A pressure gauge is installed on the upper part of the metal container. The outlet of the nitrogen cylinder is connected to the inlet of the pressure reducing valve. The outlet of the pressure reducing valve is connected to the inlet of the first connector. The outlet of the first connector is connected to the inlet of the first solenoid valve. The outlet of the first solenoid valve is connected to the inlet of the metal container. The outlet of the metal container is connected to the inlet of the second solenoid valve. The outlet of the second solenoid valve is connected to the inlet of the second connector. The outlet of the second connector is connected to one end of the air pump. The other end of the air pump is connected to the external environment.

2. The device for measuring the gas emission coefficient of radon generated by radium decay in lunar soil as described in claim 1, characterized in that: The first and second connectors enable the metal container to be detachably connected.

3. The device for measuring the gas emission coefficient of radon generated by radium decay in lunar soil as described in claim 1, characterized in that: The lunar soil was placed in a mug that comes standard with a sodium iodide gamma spectrometer, and the mug, along with the lunar soil, was placed into a metal container.

4. The device for measuring the gas emission coefficient of radon generated by radium decay in lunar soil as described in claim 1, characterized in that: The metal container is made of steel.

5. A method for measuring the radon emission coefficient generated by radium decay in lunar soil as described in any one of claims 1-4, characterized in that: Includes the following steps, 1. Seal the lunar soil to be tested in a metal container. Connect the metal container to the pressure reducing valve and the air pump via the first and second connectors. Control the opening of the pressure reducing valve, the first solenoid valve, and the second solenoid valve. Start the air pump and adjust its flow rate. Observe the air pressure value inside the metal container measured by the pressure gauge in real time. Adjust the air pressure value inside the metal container to a pressure of [insert pressure value here]. P i The air pressure P i To simulate the pressure of a high-vacuum environment and maintain it for more than 6 hours; then, the pressure reducing valve, the first solenoid valve, and the second solenoid valve were closed, and the first connector and the second connector were disconnected. The metal container was placed in the lead chamber for measurement, and the radon activity in the lunar soil particles was recorded as follows. A Pi-Rn1 ; 2. After placing the metal container and the lunar soil inside for 28 days, repeat step one to adjust the air pressure inside the metal container to a pressure of [insert pressure here]. P i The radon activity in lunar soil particles was measured and recorded as follows, and maintained for at least 6 hours. A Pi-Rn2 ; III. A one-to-one correspondence was used to record the radon activity in multiple groups of lunar soil particles, denoted as... A Pi-Rn1 The radon activity in lunar soil particles measured again after 28 days is recorded as follows: A Pi-Rn2 Substituting the obtained data into the following radon emission coefficients under different air pressures... k Pi Calculation formula: （1） The measured radon activity was substituted into the formula for fitting to obtain the relationship curve between the gas ejection coefficient and the air pressure. The air pressure value on the moon was then substituted into the fitted relationship curve between the gas ejection coefficient and the air pressure to obtain the predicted value of the gas ejection coefficient of the lunar surface soil at normal temperature.

6. The method for measuring the radon emission coefficient generated by radium decay in lunar soil as described in claim 5, characterized in that: The air pressure inside the metal container is a series of air pressures that are less than one atmosphere.

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