A silicon based cosmic ray telescope as an external tracker to measure detector performance

High energy physics experiments in the intensity frontier push at the limit the detector resolutions. This is the also case for the upgrade of the MEG experiment that requires a design of a new drift chamber to track 52.8 MeV positrons with a single hit resolution of about 100 μm. In order to to compare the tracking performances of various prototypes implementing different cell configurations, a high resolution cosmic ray telescope is required. We built our telescope by assembling four spare ladderts of the external layers of the Silicon Vertex Detectors of the Babar experiment. This test facility operating at INFN sezione di Pisa provides the detector under test with an external track with a resolution of 15 μm on the DUT plane. The DAQ originally used in the Babar experiment had to be replaced by a custom design boards coupled with an acquisition front-end PC through commercial FPGA evaluation boards.