New OSL detectors based on LiMgPO4 crystals grown by micro pulling down method. Dosimetric properties vs. growth parameters

Abstract

Rod-shape crystals of the LiMgPO4 compound were grown by micro pulling down technique under the different growth conditions. Influence of the different growth rates, thermal setups and gaseous atmospheres on the crystals dosimetric properties was investigated. Samples were irradiated with 90Sr/90Y β particles and optically stimulated luminescence spectra were measured with the automatic Risø TL/OSL-DA20 reader. The sensitivity level, repeatability, dose–response dependence and short-time fading were compared for all grown crystals. It was found that the crystal grown from the iridium crucible was about three times more sensitive to radiation as compared to the crystal grown from the graphite crucible. Also the radio-sensitivity measured for the crystals grown from the graphite crucible was higher in case of higher growth rates. It was also shown that the residual OSL signal measured one and two weeks after the irradiation was higher for the crystals grown with higher growth rates. There was also no correlation observed between the growth conditions and the level of dose–response nonlinearity. Over the studied dose range the response nonlinearity of the studied samples fluctuated around over a dozen percent, regardless of the applied growth parameters. The obtained results tend to suggest that LiMgPO4 crystals may be considered as promising dosimeters in different fields of research.