Tupitsyna I. Cadmium tungstate crystals with improved scintillation parameters

In the work the complex investigation of intrinsic defects of CdWO4 crystals and admixing defects of doped crystals to optical and scintillation characteristics have been carried out. The intrinsic defects of CdWO4 crystals were created intentionally by the way of annealing in different gaseous mediums and with application of charge with deviation from stoichiometry. The data of the investigation have allowed to develop the technology of obtaining non-inertial scintillation single crystals of cadmium tungstate, doped by lithium compositions. The crystals received in this way are characterized by low level of afterglow in millisecond range (<0,02 / < 0,002 % after 3 ms and 20 ms, accordingly), 20000 photons/MeV light yield and high homogeneity of scintillation parameters in the whole of crystal volume (dispersion within limits of 10%). The radiation stability data of the crystals, doped by trivalent admixtures and annealed in reducing atmosphere, allowed to develop the methods of obtaining of cadmium tungstate single crystals with improved radiation stability. Doping of cadmium tungstate crystals by admixtures of Ho, Bi, Eu, Gd, Sm and others rare-earth elements with concentration of 0.0001 - 0.005 mass. % or annealing in reducing atmosphere under 550 - 800 C doesn't change scintillation parameters but provides the obtaining of scintillators with high radiation stability by gamma irradiation dose under 500000 Gr.