Luminescence response to irradiation using mini X-ray generators

Determination of equivalent doses in retrospective dosimetry involves calibration by irradiation of the dosimeters in the laboratory. In the Risø TL/OSL measurement system, laboratory irradiations make use of a radionuclide (90Sr/90Y beta) source. In this paper we investigate the possibility of replacing the radionuclide source with an X-ray tube. Two different X-ray tubes are tested; a filament type (50 kV, 1 mA, 50 W) and a cold cathode type (30 kV, 0.1 mA, 3 W). We show that the horizontal dose uniformity and irradiation cross-talk are improved compared to the beta source and that the reproducibility is comparable. The relationship between X-ray dose rate and tube current is highly linear for both tubes. OSL decay curves, growth curves and dose distributions from various thermally annealed quartz samples are also presented. Finally it is shown that, unlike for a beta source, the calibration factor obtained using low energy X-rays is sample dependent.