A simple design concept for elimination of the impact of humidity on radon measurements using electrostatic collection

Abstract

The detection efficiency of electrostatic collection radon monitors is influenced by the humidity of the air in the collection cell. This is due to the recombination of positively charged 218 Po with OH -ions, whose concentration depends on humidity. A novel design of an electrostatic collection cell, in which the air pressure in the cell is less than the atmospheric pressure, is proposed to eliminate the impact of humidity. As a result of the lower air pressure, the drift velocity of the positively charged 218 Po in the electric field increases, so the collection time decreases. A model predicting the collection efficiency of positively charged 218 Po in this kind of electrostatic collection cell is presented. Based on the model, if the air pressure in the cell is sufficiently low, the collection efficiency will be approximately a constant and the dependency of the collection efficiency of the positively charged 218 Po upon the water vapor concentration can be ignored. This approach can be applied to develop a new radon monitor.