Wavelike anomalous fading of BaSO4:Eu

In the light of the extensive use of high sensitivity thermoluminecence detectors (TLDs) the aim of the present work is to report some experimental observations and theoretical interpretations of the unusual fading of BaSO4:Eu as a function of the Eu concentration. The formation of activator associates as 8-9 atom clusters when the Eu content exceeds 1.5 mol% in one phosphor was found. Wavelike shapes of the fading dependence on storage at room temperature (300 K) and liquid nitrogen temperature (77 K) were interpreted as electron retrapping processes in the trap system of the Eu cluster. An attempt to give a kinetic description of this phenomenon is also made. (author)