Behavior of optical spectra of leucosapphire crystals under neutron irradiation

Abstract

The paper addresses the dose and temperature dependences of the formation and decoloration of visible-spectrum absorption bands for leucosapphire monocrystals subjected to treatment in a reactor core; they reveal special behavior of the material’s optical spectra as a function of flux and temperature. When taking readings of the above-mentioned functions during the high-temperature isochronal annealing, the author has identified the main stages and substages of decoloration at 460, 570, 620 nm and detected the negative annealing of these bands at some temperatures. The defect formation process has been found to proceed in stages; the activation energies and concentration of the respective centers have been determined; an assumption is made as to the nature of these centers. It has been established that the radiation kinetics of generation of a color center at 460 nm and photoluminescence at 540 nm is represented by a power law; it is assumed that there might be a single mechanism responsible for inducing these bands. The author discusses the factors that may affect the behavior of the dose dependence of the luminescence intensity with increasing neutron fluence.