Radiation damage of LSO crystals under γ- and 24 GeV protons irradiation

Irradiation damage of undoped and low Ce doped lutetium oxyorthosilicate has been investigated. Crystals were irradiated with both a 60Co γ-quanta source with an absorbed dose of 2000 Gy and, at CERN PS, a high-rate 24 GeV proton beam with a fluence of ∼3.6×1013 p/cm2. Both irradiations produced a similar set of induced absorption bands. However, a shift of the fundamental absorption spectrum cutoff appears after proton irradiation, but not in the case of the γ-irradiation. The observed shift of the band edge in the transmission spectrum following proton irradiation in lutetium oxyorthosilicate crystals indicates that this phenomenon is a general property of heavy crystalline materials. A possible proton-induced transmission damage mechanism is discussed.