Performance studies of MicroMegas for the ATLAS experiment

The performance of MicroMegas (MM) has been extensivelystudied during several test beam campaigns with high energy particlebeams at CERN up to the year 2012, and more recently (June 2013)with electron beams at DESY. Main objectives of the tests were todemonstrate that the requirements could be achieved for the upgradeof the ATLAS Muon Spectrometer, where the MicroMegas will be mounted(along with small-strip Thin Gap Chambers — sTGC) on the New SmallWheel for forward muon detection. The MM layout and operatingsettings have then been chosen to satisfy the ATLAS upgraderequirements and trigger timing constraints. Results forefficiencies, time resolution and spatial resolution forperpendicular and inclined tracks are presented. Moreover, in ATLASthe MM will operate in a non-uniform magnetic field up to 0.3 T.Dedicated test beam measurements have been carried out in a variablemagnetic field between 0 and 1 T. The performance of MM in magneticfields is also reported along with a comparison to simulations.