Impact of the scattering coefficient of scintillation crystals (LYSO and LSO) on depth of interaction resolution

Intrinsic parameters in scintillation crystals play a crucial role in the measured spatial and energy resolutions. In many cases the measurement of these intrinsic parameters is difficult to be carried out or even there are parameters that need a specific setup to be measured directly, e.g. the intrinsic light yield and the absorption and scattering coefficients. These uncertainties in the parametrization of the characteristics of the scintillation crystals make it quite difficult to evaluate the quality and characteristics of the scintillation crystals and their impact on the resolutions. Results of measurements of depth of interaction and its resolutions for three different scintillation crystals (one LSO and LYSO of two different providers) are presented. We have noticed that for one of the LYSO a worse depth of interaction resolution (ΔDOI) was obtained when compared to the other both crystals. Measurements of the transmittance of all these crystals allow us to obtain the scattering coefficient (αscatt) for wavelengths of λ=0.40–0.50 [μm].We found that different values of the scattering coefficient for the different crystals are consistent with the measured resolutions for the depth of interaction and prove the strong impact of the αscatt for each crystal on the ΔDOI.