Beta dose rate reduction for the built-in 90Sr/ 90Y sources of Risø TL/OSL automated readers

Abstract

Environmental dosimetry requires measuring doses, which are often below the range accessible with the commonly used built-in β-source of Risø TL/OSL readers. Al2O3:C Luxel® dosimeters were used to investigate irradiation cross-talk and attenuators as means to reduce the dose rate of the source. Irradiation cross-talk was found to be highly effective in reducing the dose rate but was not reproducible and resulted in dose recovery deviations of up to 80%. Four attenuator materials (PTFE, microscope coverslip glass, wine glass, and ABS plastic) were investigated with regard to their dose reduction capabilities. All materials resulted in good dose recovery results and allow building a standard reference dose response curve. Microscope cover glass reduces the dose rate by a factor of 3 for each 1 mm thickness. The material is transparent and does not have to be removed during measurement and is therefore recommended as attenuator of choice for dose rate reduction.