The measured electron response nonproportionality of CaF2, BGO, LSO, and GSO

To study the light yield nonproportionality and intrinsic energy resolution of inorganic scintillators, a Compton coincidence technique was previously designed, implemented and benchmarked. This technique provides the ability to accurately measure the electron response of scintillation materials and thus provides an accurate means of studying light yield nonproportionality. In this study, the electron responses of two “classic” scintillators (CaF₂(Eu) and Bi₄Ge₃O₁₂ (BGO)) and two newer scintillators (Lu₂SiO₅:Ce³⁺ (LSO) and Gd₂SiO₅:Ce³⁺ (GSO)) have been measured over the energy range of about 5 keV to approximately 450 keV using this technique. Electron responses for all four scintillators are observed to increase monotonically with electron energy. BGO is observed to have the least nonproportionality, with its electron response varying about 20% over this energy range. Conversely the LSO electron response is observed to vary about 50% over this energy range and thus exhibits the largest nonproportionality