The Measurement of the Size Spectrum and Charge to Total Ratio of Condensation Nuclei Having Naturally Occurring Radon Daughter Products Attached to Them

Abstract

A large number of experiments have been carried out under a variety of atmospheric conditions to measure the mobility, and hence the size spectrum, of atmospheric condensation nuclei having naturally occurring short-lived radon daughter product atoms attached to them. The ratio of the number of charged nuclei (particles) of a particular sign to the total number of particles present was also measured. The numbers of charged particles within a series of mobility, and hence size ranges, were measured by electrical separation and by counting the alpha-particle disintegrations associated with these particles. The size spectra for both positive and negative nuclei were similar and ranged in diameter between about 0.02 μ and about 0.15 μ. The size spectrum for both positive and negative particles did vary with atmospheric conditions but the range of particle diameters remained fairly constant. The ratio of the number of positively and negatively charged particles to the total number of particles varied with atmospheric conditions, the percentage number of positively charged particles being generally about twice that of negatively charged particles. The number of positively charged particles present was, however, found to be as high as 95% during a snowstorm.