Use of electrostatic collection of 218Po for measuring Rn

The decay of 222Rn produces a positively charged 218Po ion 88% of the time. The electrostatic collection of this ion has served as the basis of a number of systems for measuring Rn concentrations. However, there are neutralization processes that restrict the time available to collect the ion. The measured rates of neutralization by water vapor and by trace gases have been used to determine the applied field strengths necessary to ensure complete collection of the ions and thus interference-free Rn determinations.