Dopant concentration dependence of radiation-induced positive hysteresis of Ce:GSO and Ce:GSOZ

Positive hysteresis and radiation tolerance to high-dose radiation exposure were investigated for Ce 0.5, 1, and 1.5%-doped Gd2SiO5 (GSO) and for Zr co-doped GSO with the same Ce concentrations (GSOZ). When they were irradiated by 200-800 Gy 60Co in 200 Gy steps, all Ce-doped GSO samples exhibited light yield enhancement (positive hysteresis). On the other hand, the light yield of GSOZ decreased greatly. Ce 0.5%-doped GSO showed the highest positive hysteresis, with ∼20% light yield enhancement. When the Ce concentration was increased, the positive hysteresis became weaker.