Using liquid phase epitaxy, the Mg co‐doped multicomponent garnet film scintillators of composition((Ce0.01Lu0.27Gd0.74)3– xMgx(Ga2.48Al2.46)O12, x = 0–0.002 (0–700 at. ppm) are prepared. Following luminescence and scintillation characteristics and their dependence on Mg concentration are studied: photoluminescence emission and excitation spectra, radioluminescence spectra, photoluminescence and scintillation decay curves, light yield, energy resolution, and afterglow. At lower Mg concentration, the timing characteristics are slightly improved, while light yield and energy resolution are not negatively influenced. At higher Mg concentration, scintillation decay is significantly accelerated, although light yield is somewhat reduced. Afterglow values become extraordinarily low for a garnet scintillator, at least two times better than the best values published so far, which paves the way for their application in fast frame imaging applications. A mechanism of the improvement is shortly discussed.
