Radon progeny deposition in track-detection diffusion chambers

The sensitivity dependence for cylindrical diffusion chambers that are used for radon track-detection measurements on the deposition fraction of radon progeny atoms has been theoretically studied (sensitivity is the ratio: area track density/integrated 222Rn activity concentration). Experimentally, the sensitivity values of both the metal- and plastic-made chambers were determined. Results indicate that the experimental sensitivity for metal chambers is in accordance with the theoretical model while a deviation of 15% is observed for plastic chambers. The uncertainty in the sensitivity values that is related to possible variations of the diffusion coefficient for 218Po atoms was estimated to be less than 10%.