ATLAS Muon Spectrometer Upgrades for the High Luminosity LHC

ATLAS Muon Spectrometer Upgrades for the High Luminosity LHC The luminosity of the LHC will increase up to 2x10^34 cm-2s-1 after the long shutdown in 2019 (phase-1 upgrade) and up to 7x10^34 cm-2s-1 after the long shutdown in 2025 (phase-2 upgrade). In order to cope with the increased particle fluxes, upgrades are envisioned for the ATLAS muon spectrometer. At phase-1, the current innermost stations of the ATLAS muon endcap tracking system (the Small Wheels) will be upgraded with 2x4-layer modules of Micromega detectors, sandwiched by two 4 layer modules of small strip Thin Gap Chambers on either side. Each 4-layer module of the so-called New Small Wheels covers a surface area of approximately 2 to 3 m2 for a total active area of 1200 m2 each for the two technologies. On such large area detectors, the mechanical precision (30 \mu m along the precision coordinate and 80 \mu m along the beam) is a key point and must be controlled and monitored along the process of construction and integration. The design and recent progress in the construction will be presented, along with recent performance results from test-beam campaigns on prototypes. For phase-2, highly selective first level triggers are essential to exploit the full physics potential. The ATLAS experiment plans to increase the rate of the first two trigger levels to 1 MHz at 6 \mu s latency and 400 kHz at 30 \mu s latency respectively. This requires new muon trigger electronics and the replacement of the read-out electronics which will allow for the inclusion of the precision chambers in the first level trigger decision. ATLAS plans to reinforce the barrel muon trigger system by the installation of additional thin resistive plate chambers with a high-rate capability. This will result in an increase in the acceptance of the barrel muon trigger from 75% to 95%.