Influence of Electric Charge and Humidity Upon the Diffusion Coefficient of Radon Decay Products

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Abstract
The diffusivity of freshly formed Th decay products was studied under a variety of conditions with respect to relative humidity and electric charge and over a range of Th concentrations from about 340 nCi/l to 3.4 .times. 105 nCi/l. Of ThB(212Pb) atoms, 85-88% carried a positive charge when formed. In moist air (30 .ltoreq. relative humidity .ltoreq. 90%) the diffusivity of the positively charged ThB atoms was 0.068 .+-. 0.004 cm2/s; it was the same for neutral ThB atoms, regardless of humidity. In very dry air, the diffusivity of the charged atoms could not be established unequivocally, but it was about 0.024 cm2/s. [The inhalation of Rn and its progeny is responsible for the potential hazards in Th and U processing areas and partially for natural radiation.].