ИСТИНА

Garnets are well-known type of mixed crystal used as hosts for RE elements. Wide possibilities of isomorphic substitution of cations and introduced dopants made garnets very perspective for application as luminescent and scintillation material. One of the new functional materials of garnet type is Gd3Al2Ga3O12:Ce (GGAG:Ce). GAGG:Ce is characterized by short decay time (τ < 100 ns), high light yield (up to 50,000 ph/MeV), also its emission band corresponds to the sensitivity spectrum of conventional SiPMs. The characteristics of developed GAGG:Ce made it perspective scintillation crystal for the high energy physics fundamental studies, for security screening systems and for medical positron-emission tomography. Optical and scintillation properties of the crystals, in particular their transparency and energy transfer processes, are very sensitive to the presence of the structural defects. The absence of the general model of defect formation in GGAG:Ce is a fundamental problem, which is not solved so far. Post-growth treatments such as irradiations may lead to the defects groups distraction or creation. The aim of this work is to study the origin of the defects of GAGG :Ce by its submitting to electron irradiation. Here, we present the results of our study of the optical and luminescent properties of GAGG:Ce crystals irradiated by electron beams. All investigated samples were cut from crystals grown in JSC "Fomos-Materials" Co. using Czochralski method in Ir crucibles. Electron irradiation was performed at the Centre of Physical Measurements Investigations of IPCE RAS using the linear accelerator (energy 5 MeV, flux 4·1012 cm–2·s–1, fluence 1,2∙1016, 3,4∙1016, 8,3∙1016 cm–2). Optical properties of the samples were studied in the Accredited Testing Laboratory "Single Crystals and Stock on their Base" of NUST "MISiS" by Cary 5000 spectrophotometer with universal measuring accessory "UMA" (Agilent Technologies). The measurements of the luminescence characteristics of the crystals was performed in the Skobeltsyn Institute of Nuclear Physics using laboratory set-up with 150 W xenon lamp was used as an excitation source. The luminescence was registered using LOT-Oriel MS-257 spectrometer equipped with CCD detector.