Ce3+‐doped oxide glass with high Gd2O3 (30 mol%) concentration was prepared as a scintillating glass under CO reducing atmosphere. A dominant emission band of the Ce3+ 5d → 4f transition peaking around 400 nm was observed in the photo‐ and radioluminescence (PL, RL) spectra. PL decay was governed by a few tens of nanoseconds decay time. The integral scintillation efficiency of about 30% of the Bi4Ge3O12 scintillator was observed as well. It exhibits a light yield of about 910 photons/MeV with an energy resolution of 18.3% (FWHM) in the pulse height spectrum of 662 keV γ‐rays from a 137Cs source.

The luminescence and gamma-ray detection properties of the new cerium-doped rare-earth scintillator lutetium-yttrium oxyorthosilicate ( Lu1.95Y0.05SiO5:Ce, LYSO:Ce) were investigated and compared to those of cerium-doped yttrium oxyorthosilicate ( Y2SiO5:Ce, YSO:Ce) crystal. The light yield and energy resolution were measured using photomultiplier tube (PMT) readout. The non-proportionality of the light yield and energy resolution versus γ-ray energy were measured and the intrinsic resolution of the crystals was calculated. In spite of significant progress in light yield and luminescence properties, the energy resolution of LYSO:Ce appears to still suffer from an excess variance in the number of scintillation photons. The mass attenuation coefficient of LYSO:Ce and YSO:Ce for 662 keV gamma rays was also measured by transmission method and compared with the theoretical values calculated by WinXCom program.

1 Introduction Silica glass is an attractive host material used for studying the luminescent properties of rareearth and transition metal ions because it has good optical and mechanical properties as well as good chemical durability. Scintillating glasses can be used in bulk or fiber forms for the detection of X-rays, γ-rays and neutrons [1][2][3]. They are cheaper and easier to fabricate with respect to single crystal materials, but they suffer from concentration quenching resulting from the interaction of emission activator ions. The concentration quenching is closely related to the phenomenon of phase separation, which occurs mainly during glass melting [4].The Ce 3+ and Tb 3+ dopants are used most frequently in order to achieve fast (tens of ns) luminescence response in the blue spectral region or slow (units of ms) response in the green spectral region. Eu ion is studied both in trivalent and divalent charge state [5] and especially the latter appears to be interesting for obtaining of a broad-band emission in the blue-green spectral range with still reasonably fast decay times of few microseconds. Several groups have addressed themselves to the problem of stabilization of 2+ charge state of Eu center in an oxide glass host [6][7][8].

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