Performance parameters and uncertainty of the method for assessment of Sr concentration in small powder samples using α-Al2O3:C beta detectors

Non-destructive detection of very low concentrations of ⁹⁰Sr (about 0.4 Bq g⁻¹) inside powdered samples with masses below 200 mg (such as tooth enamel prepared for EPR measurements) is not a trivial task. Most of the conventional measurement techniques require a special chemical treatment or an enrichment process. Thin-layer α-Al₂O₃:C passive luminescence beta detectors have been successfully used for measuring dose rates due to beta decay of ⁹⁰Sr inside small samples. In this paper, a new refinement is introduced for the assessment of ⁹⁰Sr concentration in dental tissue using thin-layer α-Al₂O₃:C passive luminescence beta detectors. The performance parameters of passive luminescence beta detection (such as detection and quantification limits) have been evaluated using statistical analysis of the experimental results. The sources of uncertainty have been analyzed and the total uncertainty calculated using Monte Carlo simulations. The results of TL passive beta detection for measurement of ⁹⁰Sr concentrations are shown to be in good agreement with those obtained using low-level beta counting.