Results of the tests of a CMS tracker inner barrel sub-system with a 25 ns beam

In May 2003, a beam test was performed to validate a subsystem of the CMS Tracker with a LHC-like beam. All final components, including detectors and fully optical readout, were assembled together on a sector of the third layer cylinder mechanical support. The system, with pre-production power supplies and DAQ, was taken into the CERN X5 beam area where, after a short period of commissioning stage it collected data samples over a two weeks test period. Data were analyzed and results concerning charge collection, noise, detector performance under different bias voltages, timing structure of the signal, and detector uniformity were obtained. The main system aspects as well as the DAQ and experimental setup are described and the detector performance is discussed.