通讯机构：
[Tana, YL ] H;Hengyang Normal Univ, Coll Phys & Elect Engn, Hengyang 421002, Hunan, Peoples R China.
关键词：
Alpha particles;CMOS integrated circuits;Data handling;Dielectric devices;Image sensors;Ionizing radiation;Metallic compounds;MOS devices;Oxide semiconductors;Radiation protection;Semiconductor diodes;Transistors;CMOS imagers;Commercial off the shelves;Commercial off-the shelves;Commercial-off-the-shelf;Complementary metal oxide semiconductors;Natural radiation;Particle Identification Method;Photon detector;Photon detector for UV, visible and IR photon (solid-state) (PIN diode, APD, si-PMT, G-APD, CCD, EBCCD, EMCCD, CMOS imager, etc);UV-visible;Photons
摘要：
<jats:title>Abstract</jats:title>
<jats:p>Radon (Rn-222) is the main source of radiation exposure to
human beings from natural radiation; it is of great significance to
study the measuring methods and measuring instruments of radon for
natural radiation protection. In recent years, the application of
pixel detectors in radiation detection has attracted attention. In
this paper, a Commercial Off-the-Shelf Complementary Metal Oxide
Semiconductor (COTS CMOS) image sensor which replaces the glass for
protection covering in front of the sensors was used to perform a
series of measurements to identify alpha particles. During the
experiment, the CMOS image sensor was used to record a video during
the sampling period, and then use the <jats:italic>FFmpeg</jats:italic> software to take
screenshots of the video by frame. MATLAB was used to count bright
spots from the image frames. A measurement chamber was designed to
measure radon concentrations, and when the relative humidity was
constant, the count of alpha particles by the CMOS image sensor
increased along with the increase of the concentration. The
experiments verified the feasibility of the low-cost COTS CMOS image
sensors to monitor radon.</jats:p>
摘要：
The open-loop method of measuring soil radon exhalation rate is widely used to explore the influence of environmental factors on soil radon exhalation rate because it can continuously monitor and quickly respond to changes in soil radon exhalation rate. However, in the open-loop measurement, the ventilation chamber is connected to the outside environment, and under the action of the pump, the ventilation chamber will have a certain suction effect on the covered soil surface. When the soil is relatively dry, there may be some tiny cracks on the soil surface. Under the influence of suction, the gas with high radon concentration from deep soil will be more easily drawn out to the soil surface. If such a situation occurs, the radon concentration in the ventilation chamber and the results of the radon exhalation rate measurements will be abnormally high. In this paper, we investigated the effect of soil cracks on the open-loop radon exhalation rate measurements by comparing the radon exhalation rate obtained from open-loop measurements with that obtained from closed-loop measurements under the same environment. The results show that in the open-loop radon exhalation measurements, the smaller the soil cracks are, i.e., the closer the flow rate at the inlet of the ventilation chamber is to that of the pump, the higher the agreement between the radon exhalation rate obtained from the open-loop measurement and that from the closed-loop measurement.
通讯机构：
College of Physics and Electronic Engineering, Hengyang Normal University, Hunan Province, Hengyang, China
关键词：
3D modeling;Computer software;Electric power transmission networks;Electron emission;Electrons;Ions;Nuclear reactors;Accelerator modeling and simulation (multi-particle dynamic, single-particle dynamic);Charge inductions;Charge multiplication;Detector modeling;Detector modeling and simulation II (electric field, charge transport, multiplication and induction, pulse formation, electron emission, etc);Detector simulations;Model and simulation;Particle dynamics;Pulse formation;Radiation monitoring;Single-particle dynamics;Electric fields
摘要：
Developing an ultra-high sensitivity electrostatic collection radon monitor benefits the scientific experiments of China Jinping Underground Laboratory. Here, a one cubic meter electrostatic collection vessel with a multi-layer hemispherical metal grid was designed to increase the collection efficiency of positively charged Po-218 ions. The 3D model of the giant electrostatic collection vessel was constructed using the COMSOL Multiphysics simulation software, and the potential and electric field distributions in the vessel were simulated. Numerical simulation results were obtained according to the different radii and voltages applied to the grid. The electric field between the vessel wall and grid, between two grids, and between the grid and surface of the PIPS detector must be set uniformly to reduce the collection time of the positively charged Po-218 ions. Simulation results showed that setting a charged metal grid in the vessel can optimize the electric field distribution, and setting a two-layer charged metal grid in the giant vessel can further increase the cost performance. The average collection times of the electrostatic collection vessel with the two-layer grid along the vertical and oblique lines approximately 15% and 13% of that without the grid. The rates of positively charged Po-218 ions that could pass through the one and two-layer metal grids were 86.78% and 50%. Optimizing the electric field can greatly increase the sensitivity of radon monitors and reduce the humidity restrictions.
