The triple-GEM detector for the M1R1 muon station at LHCb

Twenty-four triple-GEM detectors with 20times24 cm² active area will equip the inner region of the first station of the muon detector at the LHCb experiment. After three years of R&D to prove that this detector, operated with a CF₄ based gas mixture, satisfies the stringent requirements in terms of time performance and radiation hardness, the project is entering in the construction phase. The final design of the detector, the selected materials and the construction procedure and tools will be described in details. The quality control of components, such as planarity measurements on the PCB-panels and the HV test of the GEM foil, as well as the leak test and the X-ray tomography of constructed chambers will be discussed. The chamber equipped with front end electronics, Faraday cage and HV divider is finally tested with cosmics. The construction of the detector, shared between the two production sites of Cagliari-INFN and Laboratori Nazionali di Frascati-INFN, should be completed in spring 2006. The installation is foreseen by the end of the 2006