Scintillation Mechanism of Ce3+ Doped Gd2SiO5

Measuring the spectra of absorption, luminescence and excitation, and the decay times of the luminescence, at various temperatures, we investigate the scintillation mechanism of Ce³⁺ doped Gd₂SiO₅ (GSO:Ce). We conclude that the excitation energy created by gamma-ray irradiation relaxes to the core exciton states formed by the 4f-4f transitions of Gd³⁺, and that the core exciton migrates to collide with Ce³⁺, and transfers the energy to Ce³⁺ to emit the luminescence. We also conclude that the decay time of the Ce³⁺ luminescence in GSO:Ce (70 ns for the case of 0.5 mol% of Ce concentration) is decided by the diffusion time of the core exciton. A very small value for the diffusion coefficient of the core exciton is estimated to be 7 × 10^-7cm²/s.