Effects of yttrium content on intrinsic radioactivity energy spectra of LYSO:Ce crystals

This work investigates the intrinsic radioactivity of Lu 2(1−x) Y 2x SiO5 :Ce (LYSO:Ce) crystals grown by Czochralski method (Cz) with various yttrium (shortened as Y) contents (x= 0-100 at.%). Energy spectra of the crystals excited with 137Cs and the intrinsic radioactivity related to 176Lu atoms as a function of Y content were investigated. It is illustrated that the intrinsic radioactivity depends on the content of Y, which also affects the energy spectrum and energy resolution of LYSO crystal. Results show that energy resolution of LYSO:Ce crystals can be improved by subtracting background spectra from the energy spectra. The experiment result also confirms the size effect of intrinsic radioactivity in LYSO:Ce crystal. For the LYSO crystal in large size, the influence of intrinsic radioactivity on the energy spectrum cannot be ignored, while it can be weakened by background subtracting.