Calibration of a 90Sr/90Y-source for luminescence dating using OSL

The dependence of the dose rate of a 90Sr/90Y-source commonly used for luminescence dating is investigated over a wide range of grain sizes of quartz. Three series of measurements were performed on three different backing materials with grain sizes varying between 5 and 700μm. A sharp decrease of dose rate is observed for grains <40μm due to missing build-up of secondary electrons, while there is little dependence on grain size in the region between 40 and 130μm attributed to the absorption of backscattered radiation. The effect of attenuation of dose rate with grain size becomes apparent at 180μm and does not follow a simple rule, but is interpreted to be influenced by the size attenuation and superimposed by a specific form of optical attenuation. The thickness of the backing material determines the backscatter enhancement for a given material type.