Realization and characterization of a 220Rn source for calibration purposes

Abstract The recent interest for measuring 220 Rn activity in air and the following development of the corresponding measurement techniques require the improvement of standards for the calibration and characterization of the measurement devices. Due to the short half-life of the 220 Rn, the adopted techniques for the production of 222 Rn sources are not always reliable. In this paper a methodology for realizing a thoron known activity starting from a 232 Th source will be presented and discussed.