Radon measurement by coincidence gamma-ray spectrometry

A method of radon measurement by a multidetector -ray spectrometer,based on coincidence counting of 609 keV photons from two-step cascade transitionsthat follow â – decay of 214 Bi, is proposed. Besides a good accuracy,the method has better sensitivity than some standard methods of radon measurementcurrently in use. Applying this method to the PRIPJAT-2M spectrometer with6 NaI(Tl) detectors, and counting a 1 l sample of well water for 30 minutes,a minimum detectable radon activity of 0.25 Bq/l is experimentally determined.