INFLUENCE OF ELECTRIC CHARGE AND HUMIDITY UPON THE DIFFUSION-COEFFICIENT OF RADON DECAY PRODUCTS

The diffusivity of freshly formed thoron decay products was studied under a variety of conditions with respect to relative humidity and electric charge and over a range of thoron concentrations from ~340 nCi/1 to 3.4 x 105nCi/1. 85-88% of ThB(212Pb) atoms carried a positive charge when formed. In moist air (30% ≤ relative humidity ≤90%) the diffusivity of the positively charged ThB atoms was 0.068 ± 0.004 cm2/sec; 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/sec. © 1979 Health Physics Society.