Design And Implementation Of Air Radon Monitor In α Energy Spectrum Based On Static Electricity Accumulation Method

In recent years, radon hazards to human health have attracted wide attention, so air radon measurements become a popular technology for environmental monitoring. In this paper, author aims at the existing domestic and international air radon measurement methods and measuring instruments, and analyzes their deficiencies: The commonly used method for air radon measurement is the total amount measurement of radioactive particles, which is not able to distinguish between radon and its daughters. The existing radon monitors inαEnergy Spectrum, such as the RAD7 radon monitor inαEnergy Spectrum produced by the United States, use dynamic pumping way to collect radon gas, and then destroy the radon gas field balance in the measurement environment, so the measurement error will exist.In order to overcome the technical deficiencies of most of the air radon monitor, we design a kind of air radon monitor inαenergy spectrum based on static electricity accumulation method aiming at air radon concentration measurement requirements of high measurement sensitivity, ability of distinguishing between radon and its daughters.In this paper, the air radonαspectrum measurement theory is elaborated in the first. And then,αenergy spectrum measurement based on static electricity accumulation method is theoretically confirmed and proposed: Whenαradiator, which be adsorbed to the detector surface, decays on the surface of the detector surface, energy ofαparticles produced from theαdecay basically will not lose in the air, so thatαspectrum measurement is feasible. Based on this method, a kind of air radon monitor using gold silicon surface barrier semiconductor detector is designed.The air radon monitor inαenergy spectrum based on static electricity accumulation method, using a single-chip micro-processing system as its core, is a integrated applications system for acquisition and processing of theαenergy spectrum data. The data acquisition system can accomplish the whole process of acquisition and analysis of theαenergy spectrum data. We improve the measurement sensitivity of the instrument using the detector with large sensitive detect area and large volume electrostatic chamber of radon gas collection. The simultaneous measurements of temperature and humidity are used to modify the radon concentration measurement, so improve the accuracy of measurement data. Theαspectrometry measurement can effectively distinguish between radon and its daughters and measure respectivelyαcounts of radon daughters 218Po and 214Po, so especially increase 218Po measurement accuracy, and then the concentration of radon in air can be determined.The work is done as follow: The instrument detection device is selected. The application of measurement principle is determined. We designed and debugged low-noise signal conditioning circuit, multi-channel analyzer, microprocessor systems, low-power power management module and the corresponding software system. Environmental air temperature and humidity measuring module, real-time clock module and the latest self-luminous OLED display are integrated in the instrument. Radon gas collection device produced and theαenergy spectrum analysis system are integrated together. System performance of the equipment is test and the deficiencies found will be changed.After calibration of standard radon chamber, we get energy calibration curve, the energy resolution, conversion factors and measurement sensitivity and other important information of the instrument. In particular, it is found that measurement sensitivity of the instrument over RAD7 radon monitor. Through the analysis of experimental data, we can conclude that static electricity accumulation method is feasible, and instrument performance basically complies with the relevant national standard of radon detection in air.The air radon concentration in some point can be read directly from the display of air radon monitor inαenergy spectrum based on static electricity accumulation method. It applies to lots of fields, such as environmental radiation surveillance of civil engineering indoor radon levels, pollution control, radon concentration surveillance in standard radon chamber, and radon concentration surveillance in mine tunnels and Subway. It has the characteristics of high measurement sensitivity, simple structure, low power consumption, small size, light weight, being easy to operate.