Precise timing resolution measurements of GSO scintillators with different Ce concentrations combined with silicon photomultipliers

Abstract

Ce doped Gd2SiO5 (GSO) is a scintillator which has relatively fast decay time, high density, high light output, and is used for commercial PET systems. However as time (TOE) PET systems become more popular in clinical diagnostic, GSO seems less attractive, because its performance is thought to be insufficient for use in TOF-PET application. Although the timing resolution of the GSO combined with photomultiplier tube (PMT) is known to be inappropriate for TOF-PET system, the performance of GSO coupled to silicon photomultipliers (Si PM) has not been reported to date. In addition, GSO possesses a variety of decay Limes depending on as Cc concentration. We measured basic performance of GSOs with differenL Cc concerti:rations and then coupled Lhem Lo Si-PMs Lo measure LAte precise Liming resolution using a high bandwidth di;,YiLal oscilloscope. The decay time of GSO with 0.4 mol% Ce were longer (63 +/- 4 ns) compared with those with 1.0 rnol% (40 +/- 2 ns) and 1.5 rnol% (33 +/- 1 ns). With a Si PM. Lhe photo peak channels were almost Lhe same for GSOs with 0.4 rnol% Cc and Lhose with 1.5 mol% Ce, bur the GSO with 1.0 mol% Cc was similar to 25% higher. Energy resolutions of these three GSOs were similar to 13% full width ar half maximum (FWHM) for 662 keV gamma phoLons without correcting for saLuraLion effects. When coupled to Si-PMs, the timing resolution for GSO with 1.5 mol% Ce (decay time 33 ns) was 549 ps FVVHM, almost good enough to use for TOF-PET system. The combination of GSO with 1.5 mot% Ce with Si-PM will be an interesting combination to realize low cost TOF-PET systems. (C) 2015 Elsevier B.V. All rights reserved.