TL and OSL studies on neutron irradiated pure α-Al2O3 single crystals

alpha-Al2O3 single crystals were irradiated to various thermal neutron fluences in the range of 10(14) to 10(18) n/cm(2) with associated fast neutron fluence and gamma rays in the CIRUS reactor. The neutron irradiation of alpha-Al2O3 crystals in the reactor introduces considerable oxygen vacancies in the crystals, which is confirmed by the presence of F (203 nm) and F+ (225 and 255 nm) bands in their optical absorption (OA) spectra. The concentration of the F and F+ centers increases with the increase in neutron fluence and are responsible for the observed TL and OSL in the alpha-Al2O3 single crystals. The F/F+ concentration ratio of alpha-Al2O3 samples irradiated to thermal neutron fluence of 10(18) n/cm(2) (with an associated fast neutron fluence of 7 x 10(15) n/cm(2)) is 0.68. The photoluminescence and OA studies indicate formation of excess F+ center in the neutron irradiated Al2O3 single crystals. The TL glow curve of the reactor neutron irradiated Al2O3 is different from the TL glow curve structure of the TLD-500 single crystal. (C) 2011 Elsevier Ltd. All rights reserved.