Determination of deposition behaviour of 218Po from track density distribution on SSNTD in diffusion chamber

The radial distribution of track density on an LR115 detector inside a diffusion chamber used for radon measurements was found to be a function of the deposition fraction f1 of 218Po before decay. Therefore, the track density distribution could be used to determine f1. Examples of sensitivity distributions were shown for different chamber dimensions in this work, and large chambers were found to be the best for the study of f1. Furthermore, the radial track density distribution and the detector sensitivity were also found to be variable for different detector sizes. The uncertainty in radon measurements due to unknown f1 was estimated for cylindrical chambers with different dimensions. It was found that smaller chambers possessed internal stability against f1 while larger chambers had uncertainties depending on f1 and could have uncertainties reaching as high as 30%.