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. lit the framework of the INFN R&D project FACTOR (Fiber Apparatus for Calorimetxy 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 (V-BD), gain and dark count rate are compared for the different devices. Results about the study of the dependence of both VBD and dark count rate on temperature (in the range 0-50 degrees 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.