In this paper, we report on experimental results towards the development of near-infrared (NIR)-emitting scintillators based on rare-earth-doped garnet crystals, which were obtained as a part of collaborative research with the Nuclear Power Safety Technology Research Center, Chubu Electric Power Co., Inc. A series of garnet scintillators, Y 3 Al 5 O 12 (YAG) and Y 3 Al 2 Ga 3 O 12 (YAGG) doped with rare-earth elements (Nd, Sm, Ho, Er, Tm, and Yb) at varying concentrations (0.5, 1.0, 2.0, 5.0,

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... d 10.0 mol%), were synthesized by the floating zone method and systematically characterized for NIR-emitting scintillator applications. Among all the samples, 5% Nd-doped YAG showed the highest scintillation intensity (integration mode). By taking the spectral responsivity of the photodetector and the attenuation of optical light guide into consideration, a combination of 5% Yb-doped YAG and an InGaAs detector is expected to give the highest detectable signal. The scintillation intensity effectively depends on the photoluminescence quantum yield and energy transfer efficiency, which is effectively correlated with not the quality of the crystal but the type of rare-earth ion doped.