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Oxide scintillator detectors
Lučeničová, Zuzana ; Kučera, Miroslav (advisor) ; Bryknar, Zdeněk (referee) ; Mihóková, Eva (referee)
The presented thesis focused on the study of a new material concept of Ce3+ doped multicom- ponent aluminum garnets (GdLu)3(GaAl)5O12. High purity single crystalline epitaxial films were grown by the method of liquid phase epitaxy from the BaO-B2O3-BaF2 flux with spe- cial emphasis on the elimination of the potential impurities coming from the flux. Combined experimental study of photoelectron yield (under alpha excitation), decay kinetics of fast and delayed recombination in the milisecond time range (under e-beam excitation) and photo-, cathodo- and radio-luminescence spectroscopies were used to characterize the studied mater- ial. The single-step nonradiative energy transfer from the donor Gd3+ to an acceptor Ce3+ was observed in the low Gd, Ce doped LuAG films and established as long-range dipole - dipole interaction. Special attention was devoted to the positive effect of combined Gd and Ga substitution on the extensive suppression of shallow traps, which are responsible for the slow component in the scintillation response. The best obtained scintillation characteristics of the studied epitaxial films were comparable with the top performance bulk crystals. 1
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New detectors for low-energy BSE
Lalinský, Ondřej ; Schauer, Petr ; Kučera, M. ; Hanuš, M. ; Lučeničová, Z.
Backscattered electrons (BSE) are mostly used to study the specimen’s topography. Nowadays, low energy (units of keV) electron beam imaging is often necessary for example for the research of nanomaterials, biomaterials or semiconductors. Because BSE detectors are mostly non-accelerating or low-accelerating, electrons with approximately the same energy as primary beam (PB) have to be detected. Therefore, BSE detectors need to become optimized for such low-energy electrons. For the scintillation detectors, the biggest problem probably lies in the scintillator. Semiconductor detectors aren’t studied in this work. Cerium activated bulk single crystals of yttrium aluminium garnet (YAG:Ce)Ce(X):Y(3-X)Al(5)O(12) are widely used as scintillators for the detection of high-energy backscattered electrons (BSE). However, commonly used YAG:Ce single crystal strongly loses its light yield (LY) with the decrease of the PB energy. As possible available alternatives for this application, bulk single crystals of yttrium aluminium perovskite (YAP:Ce) Ce(x)Y(1-X)AlO(3) and CRY018 can be predicted. However, similar LY drop can be expected also with these scintillators.
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