摘要：
The collection efficiency of the hemispherical radon monitors based on electrostatic collection is strongly influenced by the electric field distribution and the relative humidity. Previous studies have been restricted to fitting the electric field using a single-segment, resulting in poor fitting optimality and accuracy. Overestimating or underestimating the fitted value relative to the true value can lead to inaccuracies in estimating the collection efficiency. To address this problem, the aim of this paper is to accurately characterize the electrostatic field of the hemispherical radon monitors using COMSOL software and to fit the potential in a segmented fitting approach. The two-segment fitting method was employed to divide the electric field inside the hemispherical radon monitor into two distinct parts for fitting. The improved fitting model increase the goodness-of-fit by 11.6% over the single-segment fitting model, and improves the accuracy of the collection efficiency of 218Po at different humidity levels. The saturation collection efficiency is also raised, especially when the humidity is greater than 10%, the saturation collection efficiency is increased by 9.2%. Through the improved method, the collection efficiency of 218Po in the hemispherical radon monitor can be accurately estimated and provide technical support for optimizing the electric field of the radon monitor.
The collection efficiency of the hemispherical radon monitors based on electrostatic collection is strongly influenced by the electric field distribution and the relative humidity. Previous studies have been restricted to fitting the electric field using a single-segment, resulting in poor fitting optimality and accuracy. Overestimating or underestimating the fitted value relative to the true value can lead to inaccuracies in estimating the collection efficiency. To address this problem, the aim of this paper is to accurately characterize the electrostatic field of the hemispherical radon monitors using COMSOL software and to fit the potential in a segmented fitting approach. The two-segment fitting method was employed to divide the electric field inside the hemispherical radon monitor into two distinct parts for fitting. The improved fitting model increase the goodness-of-fit by 11.6% over the single-segment fitting model, and improves the accuracy of the collection efficiency of 218Po at different humidity levels. The saturation collection efficiency is also raised, especially when the humidity is greater than 10%, the saturation collection efficiency is increased by 9.2%. Through the improved method, the collection efficiency of 218Po in the hemispherical radon monitor can be accurately estimated and provide technical support for optimizing the electric field of the radon monitor.
通讯机构：
[Yang, H ; Tan, YL ] H;Hengyang Normal Univ, Coll Phys & Elect Engn, Hengyang 421008, Hunan, Peoples R China.;Hengyang Normal Univ, Coll Life Sci, Hengyang 421008, Hunan, Peoples R China.
关键词：
Radon in water;Continuous measurement;Bubbling method;Equilibrium time
摘要：
Radon can move freely through air and water. Water radon measurement is a method of earthquake monitoring and water radon can be used as an environmental tracer to follow transit pathways. A novel bubbling device was developed for continuous detection of waterborne radon levels. Equilibrium between water and gas-phase radon concentrations in the gas path of this device is attained through circulation and bubbling. Monitoring gas radon allows dynamic tracking of water radon concentration. At the temperature of 22.6 degrees C, the device exhibits a sensitivity of 0.0016 CPM/Bq/m3 and detects concentrations within the range of 0.96-180,000 Bq/m3.
通讯机构：
[Tan, YL ] H;Hengyang Normal Univ, Coll Phys & Elect Engn, Hengyang 421008, Hunan, Peoples R China.
关键词：
Models and simulations;Dosimetry concepts and apparatus;Analysis and statistical methods
摘要：
The knowledge of the soil radon levels is important for the planning and construction of new buildings in order to estimate the radon risk and to classify the ground for construction purposes. A simple device was developed to simulate the vertical migration of radon in soil. The device simulates the vertical migration of radon in two different cases. The first case: simulates radon vertical migration in soil in a natural environment. The top of the device is open, while the around and bottom are sealed. The second case: simulates the vertical migration of radon in soil under the surface of a concrete floor. The device is sealed all around, including the top and bottom. A total of two sets of experiments were conducted in this study, each set of experiments simulated the migration of radon under two different cases. According to the research results, the potential radon concentration under the concrete floor is much higher than the natural potential radon concentration. Therefore, this factor must be fully considered when selecting the building materials and designing radon protection materials.
通讯机构：
[Tan, YL ] H;Hengyang Normal Univ, Coll Phys & Elect Engn, Hengyang 421008, Hunan, Peoples R China.
关键词：
Data handling;Radon;Respiratory system;Analyse and statistical method;Automatic tracking;Computing (architecture, farm, GRID for recording, storage, archiving, and distribution of data);Computing architecture;Data processing methods;Decay products;Energy spectrum;Radon concentrations;Radon measurements;Vertexing algorithm;Digital storage
摘要：
Radiation measurements are critical in radiation physics, and it is vital to recognize the potential adverse effects on human health. Ra-226 constitutes the primary naturally occurring radioactive element in soil, holding substantial effect on both human health and the environment. Traditional method for determining Ra-226 activity through gamma spectrometry necessitates an extended sample holding time to allow for the ingrowth of radon (approximately seven Rn-222 half-lives, equivalent to 27 days). It is essential to develop a novel method for rapidly and accurately determining the activity of Ra-226 in soil. A novel method using a NaI (TI) spectrometer was developed to accurately determine the Ra-226 activity in soil. Several experiments were performed. The experiment results indicate that the Ra-226 activity values in the soil samples obtained by nonlinear fitting of the measurement data from the initial five days were in good agreement with the measured Ra-226 activity values in the soil samples after 27 days. It indicates that the novel method can be applied to rapidly and accurately determine the Ra-226 activity in soil.
通讯机构：
[Tan, YL ] H;Hengyang Normal Univ, Coll Phys & Elect Engn, Hengyang 421008, Hunan, Peoples R China.;Hengyang Normal Univ, Hengyang 421008, Hunan, Peoples R China.
关键词：
One-dimensional diffusion;Accumulation chamber;Radon exhalation rate;Fick’s law
摘要：
In this paper, One-dimensional diffusion of radon in the natural environment was used to simulate by a simple device. According to experimental results, combined with Fick's law, it can be fitted that the effective diffusion coefficient De of radon in the soil in this experiment is 1.8 x 10-6 +/- 6.6 x 10-7 m2s-1, the soil radon equilibrium concentration is 25.1 +/- 2.4 kBq/m3, the radon exhalation rate on the soil surface is 47 +/- 17 mBqm-2 s-1. The radon exhalation rate of soil surface was measured twice by an accumulation chamber, the measured results are similar to the calculated results.
通讯机构：
[Tan, YL ] H;Hengyang Normal Univ, Coll Phys & Elect Engn, Hengyang 421008, Hunan, Peoples R China.
关键词：
Dosimetry concepts and apparatus;Gaseous detectors
摘要：
Radon exhaled from rocks, building materials, and soil can be harmful to human health, so it is necessary to measure radon and its exhalation rate. In this paper, a novel method is proposed to simulate radon exhalation from different medium surface by using a solid Rn-222 source, and the radon exhalation rate can be adjusted by replacing radon accumulation chambers with different bottom areas. Firstly, an experiment was done to determine the activity of the Rn-222 source, and then the theoretical radon exhalation rate can be quickly calculated from the relationship between the radon source activity and the bottom area of the radon accumulation chamber. Three sets of comparative experiments were conducted using two radon accumulation chambers with different volumes, respectively. Comparing the average values obtained from the experiments with the calculated theoretical values, it can be obtained that the differences corresponding to the two radon accumulation chambers between the theoretical radon exhalation rates and the experimentally average values are all within 6%. Without replacing the radon source, the radon exhalation rate is inversely varies with the bottom area of the chamber. Therefore, the correctness of adjusting the radon exhalation rate by replacing radon accumulation chambers with different bottom areas to simulate radon exhalation from different media surfaces is verified. This method can be used to calibrate the radon exhalation measuring instruments.
通讯机构：
[Yanliang Tan] C;College of Physics and Electronic Engineering , Hengyang Normal University, Hengyang, Hunan Province 421008, China
摘要：
Radon-222 (Rn-222) exhalation rate is vital for estimating radiation risk from many kinds of materials. AlphaGUARD measures the radon concentration based on the ionization chamber principle, which is currently recognized as a reference instrument to measure radon. In China, measurements of radon exhalation rate are performed by AlphaGUARD operated in flow-through mode on a reference device to verify measurement accuracy. These measurements are performed in both open and closed loop. AlphaGUARD can fast rapidly the variation of the radon concentration in the chamber, which is tightly pressed against the surface of the medium to accumulate the exhaled radon. When the model is used to obtain the radon exhalation rate, the radon exhalation rates obtained by nonlinear data fitting on the measured radon concentrations are similar to the reference value of the device. The difference of radon exhalation rate values of six measurements is small.
通讯机构：
[Tan, YL ] H;Hengyang Normal Univ, Coll Phys & Elect Engn, Hengyang 421008, Hunan, Peoples R China.
关键词：
Control systems;Data acquisition;Radioactivity;Radon;Semiconductor detectors;Silicon compounds;Timing circuits;Control system architecture;Data acquisition circuit;Detector control system (detector and experiment monitoring and slow-control system, architecture, hardware, algorithm, database);Detector control systems;Hardware algorithm;Monitoring control;Radon monitors;Slow control;Solid state detectors;Ultra-high-sensitivity;Electrostatics
通讯机构：
[Yanliang Tan] C;College of Physics and Electronic Engineering, Hengyang Normal University, China
关键词：
Radon concentration in water;RAD7;H2O accessory;Bubbling method;Conversion coefficient;Drying tube
摘要：
Durridge Company offers RAD7 and H2O accessory to measure the radon concentration in water based on bubbling method. There are two types of small sample bottles: 40 mL and 250 mL. The company also provided a big bottle with the volume of 2500 mL to measure the radon concentration in water. For the 40 mL and 250 mL sample bottles, the conversion coefficients are 25 and 4, respectively. The small drying tube of water accessory contains only 30 g desiccant, which makes it inconvenient to measure for a long time and needs to be replaced frequently. Besides, the 2500 mL sample bottle with big drying tube needs longer response time. In this paper, a big drying tube with long lifetime is utilized to measure the radon concentration in water. Generally, the response time and the sensitivity depend on the volume of the sample bottles and the gas circuit, so it is important to obtain the conversion coefficients under different conditions to meet different measurement demands. A novel model is proposed for describing the radon concentration in the gas circuit to obtain the con -version coefficients for any volume of sample bottle and drying tube. By choosing the appropriate time of bubbling and measuring, this model can be utilized to obtain the radon concentration in water.
作者机构：
[Tan, Yanliang; Lin, Fen; Hu, Tao; Yuan, Hongzhi; Mo, Yixiang; Fan, Zhongkai] Hengyang Normal Univ, Coll Phys & Elect Engn, Huangbai Rd 165, Hengyang 421008, Hunan, Peoples R China.;[Xie, Lin] Hengyang Normal Univ, Coll Math & Stat, Huangbai Rd 165, Hengyang 421008, Hunan, Peoples R China.
通讯机构：
[Yanliang Tan] C;College of Physics and Electronic Engineering , Hengyang Normal University, Huangbai Road 165#, Hengyang, Hunan Province 421008 , China
摘要：
<jats:title>Abstract</jats:title>
<jats:p>As Rn-222 decays, an alpha particle is emitted and the residual polonium nucleus recoils in the opposite direction. At the end of the recoil path, 88% of the polonium atoms have a positive charge and 12% are neutral. The electric potential distribution in the 60ml hemispherical internal cell of the radon monitor based on electrostatic collection is studied for reducing the combined probability of the positively charged Po-218 and the OH− produced by the ionization of water vapour in the air. The COMSOL software is used to simulate the electric potential distribution in the internal cell of the radon monitor based on the electrostatic collection method at 27°C, a pressure of 0.1 Mpa. For improving the collection efficiency of Po-218 ions, the average collection time along vertical and oblique lines is calculated when the upper surface of the internal cell is plastic, uncharged metal and charged metal, respectively. Assuming that the gas in the internal cell is uniformly distributed, the results show that if the upper surface of the hemispherical internal cell is plastic or uncharged metal, the electric potential formed in the internal cell is more uniform, and it is beneficial to reduce the total collection time of the positively charged Po-218 ions, thereby improving collection efficiency. The simulation results can be used as an effective reference for optimizing the design of the internal cell structure of the radon monitor based on electrostatic collection method.</jats:p>
摘要：
A new radon monitor with a 50 mL hemispherical internal cell (Hynu EIRM) is designed to develop a radon monitor with less influence of humidity based on electrostatic collection and CR-39. The collection efficiency of Po-218 ions in the Hynu EIRM while the cell-wall voltage is 2000 V is estimated by a model established previously. The collection efficiency of Po-218 ions under the relative humidity of 1% is 4.81% higher than that under the relative humidity of more than 10%. Several verification experiments are performed. The Hynu EIRMs are used to measure the Rn-222 concentration under three relative humidity ranges: 5%–10%, 60%–70% and 98%–100%. Results show that the largest difference of the calibration factors of the three experiments is 9.24%, which is a little larger than the difference (4.81%) estimated by the model. The reasons for this outcome may be that the simplified model underestimates the differences of the collection efficiency under different relative humidities and the statistical uncertainty in the experiments. The difference of the calibration factors of the Hynu EIRM at any relative humidity is less than 10%. This study is the first time that the influence of humidity on the detection efficiency of radon monitors based on electrostatic collection and CR-39 is reduced by decreasing the volume of the internal cell and increasing the cell-wall voltage.
