Speaker
Description
Collaboration
ATLAS Muon Collaboration
Summary
Large area Micromegas (MM) detectors will be employed for the Muon Spectrometer upgrade of the ATLAS experiment at the LHC. A total surface of about 150 m^2 of the forward regions of the Muon Spectrometer will be equipped with 8 layers of MM modules. Each module covers a surface area of
approximately 2 to 3 m^2 for a total active area of 1200 m^2. Together with the small-strips Thin Gap Chambers, they will compose the two New Small Wheels, which will replace the innermost stations of the ATLAS Endcap Muon tracking system in the planned 2018/19 shutdown. This upgrade will maintain a low pt threshold for single muons and provides excellent tracking capabilities for the HL-LHC phase. The NSW project requires fully efficient MM chambers with spatial resolution down to 100 um, a rate
capability up to about 15 kHz/cm2 and operation in a moderate (highly inhomogeneous) magnetic field up to B=0.3 T. The required tracking capability is provided by the intrinsic spatial resolution combined
with a challenging mechanical precision. The design, recent progress in the construction and results from the substantial R&D phase (with a
focus on novel technical solutions) will be presented. In the R&D phase, small and medium size single layer prototypes have been built, along with, more recently, the first two MM quadruplets in a configuration very close to the final one chosen for the NSW. Several tests have been performed on these prototypes at a high-energy test-beam at CERN, to demonstrate that the achieved performances fulfil the requirements. Recent tests applying various configuration and operating conditions, for example magnetic field dependences, will also be presented.
