Assembly of the SM1 MicroMegas chambers for the muon spectrometer upgrade of the ATLAS experiment at LHC

MicroMegas (MICRO MEsh GAseous Structure) detectors have been chosen as new precision tracking detectors for the upgrade of the forward muon spectrometer of the ATLAS experiment, composing the New Small Wheel (NSW), for their high efficiency (better than 95%), high spatial resolution and they are able to cope with high particle fluxes. The National Institute of Nuclear Physics (INFN) has been committed to built 32 micromegas chambers for the small sector of the NSW (SM1). The SM1 modules have 2 m2 surface area and they are composed of four gaps, each one made of a catodic plane, a metallic micromesh and an anodic plane with the readout strips to reconstruct the precision coordinate and the second coordinate stereo. The panels construction and the assembly procedure of the SM1 modules are presented.