Production of the high-quality CdWO4 single crystals for application in CT and radiometric monitoring

Effects of the intrinsic and dopant-induced defects in cadmium tungstate (CWO) crystals upon their luminescence and functional characteristics have been studied. It has been shown that oxygen vacancies and complexes with trivalent dopants lead to formation of deep charge carrier traps that are responsible for afterglow in the millisecond range. These defects also give rise to color centers that cause absorption in the intrinsic emission band, thus worsening scintillation parameters of the crystals. On the basis of the results obtained, an improved technological process has been developed, ensuring stable technological yield of high-quality crystals. This allowed development of scintillation elements for computer tomography with afterglow of less than 100 ppm after 20 ms and light yield of not less than 19 500 photon/MeV. Ways and advantages of the use of high-quality CWO crystals in scintillation detectors and spectrometric detection blocks are discussed.