Influence Of ²²²Rn In The Air To The Measurement Of Gamma-ray Spectrometry

Gamma-ray spectrometry is an efficient, accurate and economic method for uranium exploration and radioactivity level estimating in environmental monitoring. The atmospheric radon is an important factor of disturbance, and can directly affect the accuracy in the results of uranium or radium. Therefore, it is important to study the influence of atmospheric radon to the gamma-ray spectrometry in order to explore uranium and evaluate the ionizing radiation environment. In this paper, atmospheric radon measurement and gamma-ray spectrometry were carried out, and the relationship between them was studied.In laboratory experiments, firstly we designed a cycle system with Marin Cup, liquid radium source, air pump for measuring the response of High Purity Germanium (HPGe) gamma-ray spectrometer in high radon concentration. Then in order to study the influence of radon in air to the measurement by gamma-ray spectrometry in lab where there was relatively stable meteorology, two sets of experiments were conducted: background measurement and increased radon concentration experiment. Based on the experiments results in lab, an experiment in granite area in Beijing was performed. Finally, the paper discussed the problem of correction of atmospheric radon. The slope of the fitted line between radon concentration and the net area of the peak was considered as the conversion coefficient of radon concentration, with which the influence of radon concentration can be rectified.The research results display:â‘ radon concentration variation can affect the net areas of 352keV, 609keV and 1764keV peaks (the characteristic energy peaks of uranium) in HPGe gamma-ray spectrum, and there are positive correlation between them, but not for 232Th and 40K.â‘¡When the radon concentration in the air increased by 10Bq/m~3 , the net areas of 352, 609 and 1764keV peaks were found increased by 9.6%, 6.4%, 5.7% respectively in lab, and increased by 8.8%, 6.0%, 5.5% respectively in granite area in Beijing.â‘¢The full energy peaks of uranium series is affected by radon concentration. The higher the radon concentration is, the more obvious the positive correlation between radon concentration and the net areas of the full energy peaks of uranium series is.This research is supported by the National Natural Science Fundation of China: "The extraction of the information of Cs in the environmental gamma-ray spectrometry, and the correction of the influence of media properties and atmospheric radon" (40674067)...