First characterization of 8X8 monolithic silicon photomultipliers matrices for PET application

A small PET scanner is under development at the University of Pisa using Silicon Photomultipliers (SiPM) matrices as a photodetectors, fabricated at Fondazione Bruno Kessler (FBK). In this paper, we report on the first characterization of very large monolithic SiPMs matrices. The matrices feature 8×8 elements with a pitch of 1.5 mm. The elements are read out at the edges of the silicon die. We electrically characterized these devices at the wafer level by means of an automatic test procedure, consisting of current-voltage curves in forward and reverse bias. These tests allowed the selection of functioning devices and the evaluation of the uniformity of breakdown voltage and quenching resistance. Then, we performed first functional tests coupling the SiPM matrix to a slab of LYSO scintillator crystal. Finally, we measured the energy and spatial resolution exciting the detector with a 22-Na source.