Simulation study of gamma-ray energy response and spectral characteristics of GAGG:Ce detectors

Purpose Cerium-doped gadolinium aluminum gallium garnet (Gd₃A₁₂Ga₃O₁₂:Ce, GAGG:Ce), with its high atomic number, high light output, and good energy resolution, is crucial in nuclear radiation detection. This paper aims to systematically investigate its energy response mechanisms and spectral characteristics under different gamma energies, crystal thicknesses, and geometric configurations using Monte Carlo simulations, proposing an optimization methodology to enhance detector performance.
Methods Monte Carlo simulations were employed to model gamma-ray interactions with GAGG:Ce crystals, analyzing the impacts of gamma energy, crystal thickness, and geometric designs on energy deposition and spectral performance. The influence of surface reflectivity on energy resolution was also examined.
Results and conclusions The results show that the photoelectric effect dominates at low gamma energies (1 MeV), enabling higher energy deposition, while Compton scattering prevails at energies 1 MeV. Electron-positron pair production occurs at higher energies but does not significantly alter the stabilized energy deposition profile. Cuboid detectors achieve superior energy resolution (5.54%) compared to truncated cone designs (7.96%), attributed to reduced photon escape paths. An optimal crystal thickness of 4 mm is identified (yielding 5.54% resolution), beyond which resolution degrades due to increased self-absorption. Additionally, enhancing reflectivity from 0.7 to 1.0 linearly improves energy resolution by ~ 58.60%. This work proposes a novel optimization strategy for GAGG:Ce detector design, integrating geometry selection, thickness control, and reflectivity tuning to enhance MeV gamma-ray spectroscopy performance.