Non-proportionality study of CaMoO₄ and GAGG:Ce scintillation crystals using Compton coincidence technique

In this study, the CCT technique and nuclear instrument module (NIM) setup for the measurements of coincidence electron energy spectra of calcium molybdate (CaMoO₄) and cerium doped gadolinium aluminium gallium garnet (Gd₃Al₂Ga₃O₁₂:Ce or GAGG:Ce) scintillation crystals were carried out. The ¹³⁷Cs irradiated gamma rays with an energy (E_γ) of 662 keV was used as a radioactive source. The coincidence electron energy spectra were recorded at seven scattering angles of 30°–120°. It was found that seven corresponding electron energies were in the range of 100.5–435.4 keV. The results show that, for all electron energies, the electron energy peaks of CaMoO₄ crystal yielded higher number of counts than those of GAGG:Ce crystal. The electron energy resolution, the light yield and non-proportionality were also determined. It was found that the energy resolutions are inverse proportional to the square root of electron energy for both crystals. Furthermore, the results show that the light yield of GAGG:Ce crystal is much higher than that of CaMoO₄ crystal. It was also found that both CaMoO₄ and GAGG:Ce crystals demonstrated good proportional property in the electron energy range of 260–435.4 keV.