Correlation of optically stimulated luminescence and thermoluminescence of Al2O3:Fe, Mg, Cr crystals

Optically Stimulated Luminescence (OSL) is a technique with increasing application in radiation dosimetry. Here we present the OSL properties of an aluminum oxide single crystal, with impurities of Cr, Mg and Fe, and the correlation of the OSL signal with the thermoluminescent (TL) emission of this material. The results show a TL glow curve with at least four peaks (110, 160, 225 and 270 oC, at 5 oC s-1), with the first one fading rapidly at room temperature. As far as OSL is concerned, a high-intensity signal was observed, comparable to the signal obtained with the known OSL dosemeter Al2O3:C. There is a rapid fading of this signal, which becomes stable, with 60% of the initial intensity, after a 1000 s waiting time. The correlation of results obtained with both techniques indicates that illumination with blue light empties almost completely the first and both the highest temperature TL peaks, and moderately the most intense peak (at 160 oC). This fact is commensurate with the fading of the OSL signal, pointing to a relation of the most stable part of the signal with the high-temperature TL peaks, and showing that the shallow traps (related to the lowest temperature TL peak) contribute to the less stable OSL signal. In conclusion, our results state that this crystal can be used as a radiation OSL or TL dosemeter, if care is taken with immediate fading