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This research intends to study growths of inorganic single crystal scintillators and their characterizations for applications in various rare event search experiments, such as: dark matter and neutrionless double beta decay. In order to fulfill requirements of the applications, the scintillators should have high light yields, low radioactive impurities, matching of the emission spectra with spectral sensitivity curves of the photo detectors. In this study, details are described in developing inorganic scintillators based on Molybednum/ Tungsten oxide materials.
A number of crystal-growing techniques are used from an earlier time. Among them, Czochralski method is generally used with a melt-growth technique for growing single crystal scintillators. This method is used for growing non-hygroscopic and oxide scintillating crystals. Using this technique large size single crystals can be grown. In this thesis, details of growing several molybdate and tungstate crystals from different phases of Li2O-MoO3, Na2O-MoO3 and Na2O-WO3 are described.
Crystals of Li2MoO4, Na2Mo2O7, Na6Mo11O36 and Na2W2O7 are grown from the Czochralski technique. Phase analysis of the crystals are carried out by X-ray diffraction (XRD) analysis at room temperature. Luminescence and scintillation properties of the crystals are studied by using different excitation sources, such as, X-rays, γ-sources, 266 nm laser, 280 nm light emitting diode (LED) and 90Sr (β) source from room temperature to 10 K. By comparing these developed crystals with some reported reference crystals, the grown scintillating crystals are shown to have good potential for two different applications, such as dark matter and neutrino less double beta decay search.
Thesis Advisor: Prof. Hongjoo Kim