Development of a triple GEM detector for the LHCb Experiment

The LHCb experiment which will be operated at the LHC accelerator aims to measure systematically all observable CP violation effects and the rare decays of the B-mesons. The reconstruction of charged particle tracks close to the beampipe will be done by the Inner Tracking system. A spatial resolution of æ < 200 π m and a small radiation length are required. At rates up to 2 ¢ 10 4 mm ° 2 s ° 1 the occupancy should not exceed a few percent to allow for efficient track reconstruction. One possible technology for the LHCb Inner Tracker is the implementation of a gas de- tector using three GEM foils to achieve the necessary gas amplification (Triple GEM detector). For the first time full scale prototypes (three different designs) of Triple GEM detectors were built. Several new developments were implemented, for example a seg- mented GEM foil and a two dimensional readout. Different techniques for assembling the detectors were developed. The timing resolution of the Triple GEM detector was investigated using a special amplifier. In several beam tests the performances in high rate hadron fluxes were studied including discharge probabilities and prevention of discharge