The development of a high-resolution scintillating fiber tracker with silicon photomultiplier readout

We present test results from a novel modular scintillating fiber tracker using silicon photomultiplier (SiPM) arrays for readout. The tracker modules are made up from 250 μ m thin scintillating fibers that are arranged in five tightly packed layers on top and on bottom of a light carbon fiber/Rohacell foam support structure. Novel, custom made SiPM arrays from Hamamatsu with a channel pitch of 250 μ m and a photon detection efficiency of approximately 50% are used for readout. From a full GEANT4 simulation the expected position resolution is 0.05 mm at a tracking efficiency of 99%. Several 860 mm long and 32–64 mm wide tracker modules were tested at the PS facilities at CERN in summer 2008 and autumn 2009 achieving high light yields of about 20 photons for a minimal ionizing particle. We will show details on the characterization of the SiPM arrays and the quality control of scintillating fibers, the construction of the fiber modules and the results in terms of tracking efficiency, noise and position resolution.