A study of silicon photomultiplier sensor prototypes for readout of a scintillating fiber / lead sheet barrel calorimeter

The GlueX collaboration is designing a detector system to study exotic hybrid meson states at the upgrade beam line of Jefferson Laboratory. The hermetic detector includes a cylindrical electromagnetic calorimeter based on the scifi design used in KLOE, SPACAL, and JETSET. Since the calorimeter will be placed within a 2.24 tesla axial magnetic field, the optimal readout solution will include a solid state photodetector known as the silicon photomultiplier. This is an array of avalanche photodiode microcells operated in geiger mode with the output summed from all the microcells. The result is a photodetector with many of the same characteristics of vacuum photomultipliers such as high gain (10⁶) and fast response, but with the additional advantage of immunity to high magnetic fields and superior quantum efficiency. This study is a report on the characteristics of a variety of prototype devices being developed by SensL of Cork, Ireland. The chief parameters being studied are photon detection efficiency (PDE), gain, dark noise, linearity, dynamic range, optimum operating voltage, and stability. This is a status report for an ongoing study.