A diffusion chamber for passive separated measurements of radon/thoron concentration in dwellings

In this research, a passive diffusion chamber has been developed for separated measurement of radon and thoron. The chamber consists of two volumes which are separated by a fiber glass filter. Two lexan polycarbonate nuclear track detectors (film) are placed inside of the volumes to detect the alpha particles of radon/thorn and/or their progenies. Another lexan polycarbonate detector covered with an optimized thickness of an attenuator is placed outside of the chamber to measure only 212Po which its concentration can be related to that of long-life thoron progeny, 212Pb. The sensitivities have been measured by 2.06 and 0.053 [tracks cm−2(kBq m−3 day)−1] values for radon and thoron respectively inside of the chamber, and 7960 [tracks cm−2(kBq m−3 day)−1] value for thoron outside of the chamber. So the system can be successfully used for separated measurement of an extended range of radon/thoron concentrations in dwellings.