A Study on Radiation Damage in Large Size LSO and LYSO Crystal Samples

This paper presents a study on radiation damage effect in large size (2.5times2.5times20 cm
³
) LSO and LYSO crystals. Optical and scintillation properties, including the longitudinal transmittance and emission spectra, the light output and light response uniformity with PMT and APD readout, are measured before and after gamma-ray irradiations with integrated dosage up to 10
⁶
rad for three LSO and LYSO samples from different vendors. It was found that the recovery of radiation damage under room temperature is negligible, indicating that radiation damage in LSO and LYSO crystals are not dose rate dependent. It was also found that the overall radiation damage in LSO and LYSO crystals is small as compared to other crystal scintillators commonly used in high energy and nuclear physics experiments.