The TOTEM GEM telescope (T2) at the LHC

The TOTEM T2 telescope will measure inelastically produced charged particles in the forward region of the LHC Interaction Point 5. Each arm of the telescope consists in a set of 20 triple-GEM (Gas Electron Multiplier) detectors with tracking and t rigger capabilities. The GEM technology has been considered for the design of TOTEM very forward T2 telescopes thanks to its characteristics: large active areas, good position and timing resolution, excellent rate capability and radiation hardness. Each o f the four T2 half arms has been fully assembled and equipped with electronics at CERN and systematically tested in the SPS beam line H8 in 2008/09. After some optimization, the operation of the GEM chambers was fully satisfactory and the T2 telescopes we re installed and commissioned in their final positions at the LHC interaction point. During the first LHC run (December 2009) the T2 telescopes have collected data, at 900 GeV and 2.36 TeV. We will present here the performances of the detector and the pre liminary results obtained using the data collected.