Various methods for calibration of equipment for activity concentration measurement of noble gases

Until recently, we have used indirect methods (modelling with solid sources, theoretical calculation, etc.) for the calibration of equipment for activity concentration measurement of noble gases. After producing our gas certified reference source (CRS) of 85Kr in a 10 l volume Marinelli beaker, direct methods can now also be used. In this paper, four calibration methods are presented. Results obtaining using these methods agreed to within ±5.0%.