Determination of ion pair concentration in air

The method is described and the results are given of determining the ion concentration in the vicinity of an alpha emitter formed by 37 MBq of 241Am on a metal sheet of 10x20 mm. The measurement was conducted using an extrapolation chamber with plane-parallel collector and voltage electrodes. The sensitive volume of the ionization chamber was defined by the collector electrode having an area of S=80.07 mm2 and by the distance between the collector and the voltage electrodes being a=3 mm. (J.P.)