Emission spectra of LSO and LYSO crystals excited by UV light, x-ray and γ-ray

Because of their high stopping power (Xo = 1.14 cm R_Moiiere = 2.07 cm) and fast (~40 ns) bright (4 times of BGO) scintillation, cerium doped lutetium oxyorthosilicate (LSO) and cerium doped lutetium-yttrium oxyorthosilicate (LYSO) crystals have attracted a broad interest in the high energy physics community. This paper presents a comparative study on emission spectra measured for large size BGO, lead tungstate (PbWO₄) LYSO and LSO samples excited by UV light (photo-luminescence), x-ray (x- luminescence) and gamma-ray (radio-luminescence). A red shift was observed between the x-luminescence and the radio-luminescence versus the surface photo-luminescence, which can be explained by internal absorption. Additional red shift and significant red component was observed in the radio-luminescence spectra measured for LSO samples. This is the only significant difference we observed between the large size LSO and LYSO samples. The origin of these red shifts and the consequence to their light output and applications in the high energy and nuclear physics experiments are elaborated.