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

α-Al2O3 single crystals were irradiated to various thermal neutron fluences in the range of 1014 to 1018 n/cm2 with associated fast neutron fluence and gamma rays in the CIRUS reactor. The neutron irradiation of α-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 α-Al2O3 single crystals. The F/F+ concentration ratio of α-Al2O3 samples irradiated to thermal neutron fluence of 1018 n/cm2 (with an associated fast neutron fluence of 7 × 1015 n/cm2) 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.