The scintillation mechanism in LaCl3:Ce3

The scintillation properties of LaCl 3 crystals, doped with Ce 3+ concentrations of 0.57, 1.0, 2.0, 4.0, and 10%, are studied under x-ray and γ-quanta excitation at various temperatures. Under x-ray excitation, characteristic doublet Ce 3+ emission is observed with a maximum at 3.7 eV. Also self-trapped exciton (STE) emission is observed with a maximum near 3.1 eV. The contribution of STE luminescence to the total light yield decreases with increasing Ce concentration. For LaCl 3 :0.57%Ce 3+ , the contribution is 33%, whereas for LaCl 3 :10%Ce 3+ it is 4%. The total light yield of the Ce 3+ -doped samples ranges from 38 000 photons per megaelectronvolt (ph MeV −1 ) of absorbed γ-ray energy to 47 000(ph MeV −1 ) for LaCl 3 :0.57%Ce 3+ and LaCl 3 :10%Ce 3+ , respectively. A model is proposed to explain the energy transfer from the host lattice to the Ce 3+ ions. At these Ce concentrations, energy transfer by STE diffusion is held to be dominant.