Performance of fast timing silicon photomultipliers for scintillation detectors

A new silicon photomultiplier has been fabricated for fast timing applications. This new silicon photomultiplier, called 'fast SPM', is fabricated with a third terminal that has a much lower output capacitance. An N-on-P type ('MicroFM') and a prototype P-on-N type ('B-proto') have been tested for their energy and timing performance. Energy resolutions of the 511 keY full energy peak were 13.7 % and 13.1% for the MicroFM and B-Proto, respectively, at 4 V overvoltage. The coincidence resolving times (CRTs) for 2 x 2 x 3 mm3 LSO crystals were 184 ± 5 ps and 157 ± 3 ps for the MicroFM and B-proto, respectively. For longer crystals (3 × 3 × 20 mm
³
), more relevant for positron emission tomography (PET) scanners, the CRT was 298 ± 9 ps and 234 ± 6 ps for the two SPM types, respectively. A moderate improvement in timing resolution was observed with bare SPMs (MicroFM), without a hermetic epoxy seal, implying that a non-negligible amount of light is lost for silicon photomultipliers with an epoxy layer.