Performance and Calibration of a 2m^2 SM2 Micromegas Detector for the ATLAS Muon Spectrometer Upgrade

The steadily increasing luminosity of LHC requires an upgrade to high rate capability and high resolution capable detector tech- nologies for the innermost station of the muon spectrometer of the ATLAS experiment. For precision tracking 4 types of 2 and 3 m2 large Micromegas quadruplets will provide 8 consecutive active layers, each with 100 μm spatial resolution per individual plane. Data taken at the 120 GeV SPS muon and pion beam in August 2017 on one 2 m2 quadruplet prototype (SM2 built by the German consortium), show spatial resolutions of 80 μm for perpendicular particle incident using charge weighted position reconstruction. An analysis using additional drift-time information gives similar good resolution also for inclined tracks. The full active area of the SM2 prototype quadruplet has been calibrated in the Munich Cosmic Ray Facility. A segmentation of the active area into 55x100 mm2 partitions enabled a detailed full area analysis of local detector properties, as geometrical quality, efficiency and pulse height.