Design Of Air Pulse Ionization Chamber For Radon Monitor

Since the radon was found in twentieth century, people started to recognize and research it.It was mainly used for geological in the early years, with the development of in-depth understanding and technology, its application is more and more widely. In the field of environmental monitoring, radioactive gas radon as a serious threat to human health, to take effective protective measures need to accurately measure the concentration of radon in the environment. In this context, which is based on the people-benefit technology research and development of science and technology project of Chengdu, existing radon monitor of sensitivity is not high, long time measurement, poor repeatability, humidity and other issues, using high sensitivity, stability good air pulse ionization chamber as detector, developed with high sensitivity, continuous measurement, as well as portability good radon detector.Through simulation of ? particle ionization process, providing a theoretical basis for the structural design of the ionization chamber, with the simulation of electric field on the ionization chamber, put forward the method to improve the detection sensitivity and the structural design of the ionization chamber protection ring. The cylindric ionization chamber has an active volume of 0.9L, diameter of 71 mm and the central electrode of 6mm.The ionization chamber shell was connected with the positive voltage, the alpha ray energy fully deposited in active volume and detected to be higher than 50%, which was beneficial to improve the measurement sensitivity.Air pulse ionization chamber of radon monitor with single chip microprocessor system as the core, the system can be integrated temperature, humidity, pressure modules for the multi-parameter analysis of the measuring data; High sensitivity, low noise preamplifier circuit and single track circuit with pulse width identification were designed, which can effectively eliminate the high frequency and low frequency signals of mechanical vibration, and realize the efficient detection of the pulse signal; The stable and reliable power supply circuit provides a reliable guarantee for the stable operation of the radon monitor. In this paper, the simple circuit diagram was given, and the functions and working principle of these circuits were introduced. Good portability of software system was programmed by C51 language; Diwen touch screen as Human-Machine Interaction, which realizes the data real-time display and storage.With reference to the People's Republic of China national verification regulation of the Radon Measuring Instruments(JJG 825-2013), the measurement results show that the repeatability, instrument response, relative inherent error and statistical uncertainty can meet the requirements.Experimental results show that the ionization chamber structure design was feasible and reasonable design of hardware and software.When ionization chamber was connected with positive high voltage can effectively improve the detection sensitivity; no electric closed ionization chamber can quickly response to the changes of environmental radon concentration; by high-voltage electrostatic adsorption to reduce the concentration of radon progeny can effectively solve the problem of radon pollution, this method can also used for the soil radon measurement. Air pulse ionization chamber system with high stability, low power consumption, light weight, graphical man-machine interface, simple operation, friendly interface, can be widely used in environmental monitoring and pollution control radon level etc.