Relative concentrations of radon-222 daughter ions in air

Abstract

The short-lived daughters of radon 222 existing as ions in laboratory air are deposited by an electric field on a foil acting as the central electrode in a cylindrical capacitor. The experiments show that the time dependence of the alpha activity from 214Po, which is determined by the relative concentrations of the daughter ions in the air, depends on the critical mobility used in the collecting system. For high critical mobilities (kc > 10−5 m2 v−1 sec−1) one characteristic decay curve was always obtained, indicating relative concentrations of 218Po, 214Pb, and 214Bi ions in the ratio 1:1.5:0.2. Experiments with critical mobilities about 10−6 m2 v−1 sec−1 gave a second characteristic decay curve, indicating relative concentrations of 218Po, 214Pb, and 214Bi ions in the ratio 1:4:5.4.