MEASUREMENT OF THE EQUILIBRIUM FACTOR BETWEEN RADON AND ITS SHORT LIVED DAUGHTER PRODUCTS USING CR-39 DETECTOR

The measurement of the equilibrium factor (F) between radon and its daughters is the main access for calculating the effective dose due to the inhalation of radon. Can and bare method was used as a passive method for measuring F through the determination of the track density ratio between bare (D) and filtered (Do) detectors. The dimensions of the used diffusion chamber were altering the measured filtered track density and therefore the resultant equilibrium factor. For this reason, high uncertainty was expected in the measured F using diffusion chambers with different dimensions. In the present study, F was derived as a function of both track density ratio (D/Do) and the dimensions of the used diffusion chambers (its volume to the total internal surface area; V/A). The obtained formula was derived from eight different diffusion chambers of volumes ranged from 11 to 370 cm3 and verified the results through an experimental application. The results showed that the mean value of the calculated F by using the derived formula of F (D/Do , V/A) was equal to 0.753 with 3.2% uncertainty as compared with 0.771 with 26% uncertainty by using the widely used function F (D/Do). The results ensure the quality of the derived function to calculate F using diffusion chambers with wide range of dimensions.