Investigation of GaGG:Ce with TOFPET2 ASIC Readout for Applications in Gamma Imaging Systems

We investigated two detector modules, each consisting of a 8 &times
8 matrix of GaGG:Ce crystals with a crystal size of 3 &times
3 &times
20 mm3 and a 3.2 mm pitch. The light is collected by a 8 &times
8 silicon photomultiplier array, with one silicon photomultiplier matching one crystal. The signals are read out and processed using the TOFPET2 ASIC. Performed laboratory tests of the detectors were performed using a 22Na source, where energy and coincidence time resolution with different optical coupling were examined between the crystals and silicon photomultipliers, as well as under various operating voltages. The mean energy resolution of 9.8&plusmn
0.6% at 511 keV was observed and it was shown that the coincidence time resolution of 384&plusmn
33 ps could be achieved. The results reassure that the GaGG scintillator is a very promising candidate for the development of imaging systems, in particular, ones utilizing Compton scattering where the energy resolution plays a critical role and a moderate timing performance is acceptable.