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Engineering of garnet scintillators by co-doping with the divalent ions of the second group appears to be a powerful tool to improve the scintillation response. It leads to a strong suppression of phosphorescence in different garnets like Y3Al5O12 (YAG), Y3Al2Ga3O12, Gd3Al2Ga3O12 and diminishing the afterglow parameter correspondingly. However, crystal co-doping with Mg2+ or Ca2+ decreases the amount of Ce3+ in the crystal and deteriorates its light yield as well. Here we report on an alternative concept to control afterglow and timing parameters of garnets by the variation of the Al/Ga ratio in the crystal. It does not affect the valence state of the Ce3+ as activating ion, but acts via the control of the thermo-induced ionization rate of the excited state of Ce3+. We applied this approach to Y3(Alx-Ga1-x)5O12 (YAGG) [1], a medium heavy scintillation material with the emission spectrum pretty matched by the spectral sensitivity of SiPMs. YAGG can be produced in fiber or bulk geometry and, similar to YAG, is produced from inexpensive raw material. The only open question was the radiation hardness of this solid solution material to high energy protons, the main contributor to crystal damage effects at collider experiments. This report presents first results on the measurement of the radiation damage effect in the garnet solid solution crystal under 190 MeV protons. It was found that the crystals show a negligible loss of the optical transmission after irradiation with fluence beyond 5x1013 p/cm2. It opens an opportunity for an application of YAGG:Ce scintillation detectors in a combination with SiPM photosensors to construct a large area detectors to operate in collider experiments, particularly in the close to beam area.
[1] O. Sidletskiy et al, Cryst Eng Comm, 2017, 19, 1001.
