Beschreibung:
Abstract. A new approach to assess the emanation of 222Rn from226Ra sources based on γ-ray spectrometric measurements ispresented. While previous methods have resorted to steady-state treatment ofthe system, the method presented incorporates well-known radioactive decaykinetics into the inference procedure through the formulation of atheoretically motivated system model. The validity of the 222Rnemanation estimate is thereby extended to regimes of changing sourcebehavior, potentially enabling the development of source surveillancesystems in the future. The inference algorithms are based on approximaterecursive Bayesian estimation in a switching linear dynamical system,allowing regimes of changing emanation to be identified from the spectraltime series while providing reasonable filtering and smoothing performancein steady-state regimes. The derived method is applied to an empiricalγ-ray spectrometric time series obtained over 85 d and is able toprovide a time series of emanation estimates consistent with the physics ofthe emanation process.