A new device for dynamic sampling of radon in air

A new system is proposed for the active sampling of radon in air, based on the well-known property of activated charcoal to retain radon. Two identica l carbon-activated cartridges arranged in series remove the radon from the air being sampled. The air passes first through a desiccant cell and then t he carbon cartridges for short sampling times using a low-flow pump. The al pha activity for each cartridge is determined by a liquid scintillation cou nting system. The cartridge is placed in a holder into a vial that also con tains the appropriate amount of scintillation cocktail, in a way that avoid s direct contact between cocktail and charcoal. Once dynamic equilibrium be tween the phases has been reached, the vials can be counted. Optimum sampli ng conditions concerning flow rates and sampling times are determined. Usin g those conditions, the method was applied to environmental samples, straig htforwardly providing good results for very different levels of activity. ( C) 2000 American Institute of Physics. [S0034-6748(00)05208-4].