  The steadily increasing luminosity of the LHC requires an upgrade with
high-rate and high-resolution detector technology for the inner end cap of the
ATLAS muon spectrometer: the New Small Wheels (NSW). In order to achieve the
goal of precision tracking at a hit rate of about 15 kHz/cm$^2$ at the inner
radius of the NSW, large area Micromegas quadruplets with 100\,\microns spatial
resolution per plane have been produced. % IRFU, from the CEA research center
of Saclay, is responsible for the production and validation of LM1 Micromegas
modules. The construction, production, qualification and validation of the
largest Micromegas detectors ever built are reported here. Performance results
under cosmic muon characterisation will also be discussed.
