Determination of the Activity Size Distribution of Radon Progeny

There has been significant progress in techniques for the determination of the activity size distribution of radon progeny. Despite this progress, many inconsistencies still exist with respect to the activity distribution, especially in the smaller particle size range. The aim of this work is to evaluate a measurement technique for determination of the activity size distribution of radon progeny, and to investigate the effect of different screen configurations and different deconvolution procedures. The measurements were performed in a large experimental chamber, using three different sets of Wire Screen Diffusion Batteries (WSDB) constructed for these studies. Aerosol concentration and size distribution in the chamber were monitored by a scanning mobility particle sizer. The Twomey and Reconstruct deconvolution methods were used to derive the activity particle size distribution from the diffusion battery data. Investigations of activity size distribution using three WSDB sets of different sensitivity ranges showed that the distributions calculated with the Reconstruct program correlate well for each battery set. It has also been demonstrated that while application of narrow spectrum battery sets sensitive to particular narrow size ranges could provide better results for these ranges, results obtained with the battery set which covers the whole spectrum are, in fact, close to those for narrow spectrum sets