Cerium-doped oxide single-crystal films for biological and radiation monitoring

Cerium-doped oxide single crystal films (SCF) on Y3Al5O12 substrate are grown and investigated for various applications: biological monitoring (with the use of Lu3Al5O12:Ce X-ray screens) and radiation monitoring of alpha- and beta-active nuclides (using Y3A15O12:Ce). Optical, luminescence and scintillation characteristics of Lu3Al5O12:Ce SCF doped by isoelectronic impurities La, Y, Sc are explored. The addition of Tb or a mixture of La and Y enhances light yield SCF relative to Y3A15O12:Ce by the factor of 1.1 to 1.5. The incorporation of Lu/sup 3+/ ions in octa-sites of the lattice enhances X-ray absorption by the factor of 2.5 to 3 for the energy range 18-60 keV. This permits one to reduce the SCF thickness down to 1.0-2.0 micron. Y3A15O12:Ce SCF has energy resolution of 8.3% and the light yield up to 0.4 of that of CsI:Tl (the absolute light yield being close to 12200 photons/MeV). Phoswich detectors are investigated which consist of two SCF for registering alpha- and beta-particles on a bulk single-crystal substrate for registering gamma-photons. Garnet-based combined scintillators can be used in aggressive environments, under rigid temperature conditions and powerful irradiation.