Characteristics of S12045(X) photon sensors for GlueX

The barrel calorimeter of the GlueX detector in Hall D at Jefferson Lab will be instrumented with 4000 large-area (1.2$\times$1.2 cm$^2$) silicon photomultipliers (SiPMs) [1]. These photon sensors have properties similar to vacuum photomultipliers, but are unaffected by high magnetic fields. In our experiment, they will operate in magnetic fields exceeding 1\,T. After extensive tests with a variety of sensors, we chose the S12045(X) custom SiPM arrays manufactured by Hamamatsu Corporation, also known as multi-pixel photon counters (MPPCs) [2]. All production units have been delivered and we have measured the photon detection efficiency (PDE), gain, dark rate, cross talk and after pulsing at three different temperatures (5, 7 and {20$^\circ$C}). We will present a summary of these measurements and the plan for use of these sensors in the GlueX experiment.\\[4pt] [1] F. Barbosa {\em et al.,} NIM A695 (2012) 100.\\[0pt] [2] Y. Qiang {\em et al.,} NIM A698 (2013) 234.