First results on SiPM characterization within the FACTOR experiment

Silicon Photo-Multipliers (SiPMs) are nowadays considered, thanks to their peculiar characteristics, very promising devices for many different applications requiring fast, reliable and compact photodetectors with single photon counting capability. In the framework of the INFN R&D project FACTOR (Fiber Apparatus for Calorimetry and Tracking with Optoelectronic Read-out), we present in this paper results on different measurements performed on several SiPMs, produced by FBK-irst (Trento, Italy) and by Obninsk/CPTA (Moscow, Russia). Fundamental SiPMs parameters, such as breakdown voltage (VBD), gain and dark count rate are compared for the different devices. Results about the study of the dependendence of both VBD and dark count rate on temperature (in the range 0o C ÷ 50o C) are also given. Finally, results from a preliminary beam test of a 1 m - long scintillator bar read-out by a wls fibre coupled to two FBK-irst SiPMs are presented.