Luminescence and Light Yield in Ce<sup>3+</sup>-Doped Y<sub>1</sub>Gd<sub>2</sub>Al<sub>5-x</sub>Ga<sub>x</sub>O<sub>12 </sub>(x=2,3,4) Single Crystal Scintillators

Abstract

The compositional dependences of luminescence properties and light yield were studied in Ce3+ -doped Y1Gd2Al5-xGaxO12 (x = 2, 3, 4) single crystal scintillators. The Gd3+→ Ce3+ energy transfer was evidenced by photoluminescence excitation spectra of Ce3+ emission. With increasing Ga content in the garnet host, the Ce3+ luminescence from the lowest 5d level (5d1) was blue-shifted due to the decrease in the crystal field splitting of the 5d levels. High light yield (LY) value of ~36,000 ph/MeV was obtained for a Y1Gd2Al2Ga3O12:Ce sample under excitation with 662 keV γ-rays. The decrease of LY value was also observed with higher Ga content due to the thermal ionization from the 5d1 level to the conduction band.