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In recent years, the scintillation properties of several cerium-doped rare earth oxyorthosilicate scintillators, Ln2SiO5:Ce where Ln = Y, La-Lu, have been reported and, in some cases, extensively studied [11-[31. In addition, binary and ternary compounds such as (Lu,Y)2SiO5:Ce, (Lu,Gd)2SiO5 and (Lu,Y,Gd)2SiO5 :Ce have been reported [3]-[7]. All of these crystals have either monoclinic P or C structures with characteristic SiO4 tetrahedra and trivalent cations occupying two unique crystallographic positions [8], [9]. The trivalent cerium activator ions are assumed to occupy the cation lattice sites and possibly interstitial positions as well. The excited Sd state of Ce3+ is split into three observable levels with luminescence emission occurring only from the lowest 5d level to the 4f ground state (∼3 eV) with a Stokes shift of ∼0.5 eV. The bandgap is about 6 eV, and the index of refraction is close to 1.8, with some variation according to crystallographic direction. Despite these similarities, in somecases, differences in scintillation efficiency, decay time, rise time, and phosphorescence time profiles have been observed. In this paper, we combine thermoluminescence measurements with the temperature characteristic of scintillation efficiency between 10 and 350 K to determine the trapping levels that may influence the scintillation and phosphorescence properties of crystals of various compositions. [ABSTRACT FROM AUTHOR]

Parity-allowed UV 5d–4f transitions characterized by a high oscillator strength make trivalent cerium an interesting activator for fast and efficient scintillator crystals. Indeed, several materials are known, in which the radiative lifetime of the Ce3+ ions is shorter than 20 ns (e.g. LuAlO3:Ce and YAlO3:Ce). For the case of BaF2:Ce, however, the value of 27 ns is known from literature. In this communication we show that the 5d–4f luminescence in BaF2:Ce is in fact faster. Having analyzed several series of time profiles recorded at various temperatures between 25 and 350 K, we conclude that the true radiative lifetime of the Ce3+ ions in BaF2 is close to 20 ns and it is the radiation trapping caused by the temperature-dependent reabsorption of cerium emission which prolongs the effective decay time. [Copyright &y& Elsevier]

Low temperature thermoluminescence of GAGG:Ce and LuAG:Pr scintillator crystals has been studied by means of the Tmax-Tstop method. It is shown that the glow curves of both materials are superpositions of discrete glow peaks and broad bands due to quasi-continuous Gaussian distributions of trapping levels. A model function has been built and trap parameters have been evaluated. [ABSTRACT FROM AUTHOR]

Abstract β-Ga 2 O 3 and β-Ga 2 O 3 :Ce crystals have been grown by the Czochralski method and their scintillation properties have been studied by means of pulse height, radioluminescence and scintillation time profile measurements. It is shown that although the scintillation of β-Ga 2 O 3 :Ce is related to intrinsic excitonic emission, the doping with Ce improves some characteristics of the material. The prominent samples of β-Ga 2 O 3 :Ce display fast 6 ns (40%) scintillation, with total light yields of about 5000 ph/MeV. Highlights • β-Ga 2 O 3 and β-Ga 2 O 3 :Ce crystals have been grown by the Czochralski method. • Semiconducting samples (pure and Ce-doped) scintillate with yields of ∼5000 ph/MeV. • Doping with Ce improves some properties of β-Ga 2 O 3. [ABSTRACT FROM AUTHOR]