Litichevskyi V. Composite scintillation elements on the base of dispersed zinc selenide and oxide scintillators

The thesis is devoted to the development of new composite materials based on the chalcogenide (ZnSe(Te), ZnSe(Al)) and oxide (ZnWO4, CdWO4, Lu2-2xGd2xSiO5(Ce), Gd2SiO5(Ce)) scintillation compounds for X-ray imaging and detection of charged particles, to the study and optimization of their scintillation properties. The results of the development of new two-component composite scintillation material based on microcrystalline grains of different compounds with the possibility of scintillation parameters varying in wide range (relative light yield - 80-150 % relatively to CsI(Tl), the efficiency of X-rays absorption - 30 to 70% for the scintillator of 1 mm in thickness, the spectral range of the luminescence - 350-750 nm) have been presented. A technology of composite scintillation materials based on ZnSe(Te), ZnSe(Al) and ZnWO4, CdWO4, LGSO(Ce), GSO(Ce) for detection of X-rays and alpha radiation has been developed. It was found that the gradient distribution of the microcrystalline grains of scintillator from larger granules (the photodetector side), to the smaller granules (the opposite side), provides an increase in light yield of the composite scintillator by 10-15% in compare to the isotropic distribution (by reducing the scattering of the scintillation signal in the adjacent to the photodetector layers) and improve the luminescence homogeneity by 5-10% (due to the reduction of losses in light signal in the small grains area by diffuse light scattering). Presented scintillation elements (panels) on the base of developed composite materials possess the high spatial resolution (up to 7 lp/mm), wide dynamic range and high luminescence intensity (up to 150 % in compare to CsI(Tl)). As a result of dissertation work the experimental production of highly efficient composite scintillators for multichannel photodetection devices in low-energy paths of multi-energy X-ray introscope systems has been organized.