ABSTRACT
Separate radon and thoron measurements in soil are very important in assessment of internal exposure due to inhalation of such radioactive gases. In this study, a low cost, small size, passive diffusion chamber has been developed for simple measurement of Radon-222 and Radon-220[Thoron] gases separately in soil. The diffusion chamber consists of two films and two fiber glass filters. Lexan polycarbonate films were used as Solid State Nuclear Track Detectors [SSNTDs] and optimized film to filter distance was obtained. Calibration factors for the designed diffusion chamber were measured using flow through method which was 16.85[track.cm[-2] [kBq. m-3d] [-1]] and 17.25 [track.cm[-2][kBq.m[-3]d][-1]] for radon for the lower and upper Lexan films, respectively and 1.76 [track.cm[-2] [kBq.m[-3] d][-1]] for thoron. The designed chamber is an economic, applicable and efficient detector for measurement of radon and thoron separately in soil