The ATLAS ‘New Small Wheel’ Muon detector stations recently commissioned for LHC Run3

Abstract

After nearly a decade of intense effort, the two New Small Wheels (NSW) for the upgrade of the ATLAS Muon spectrometer is now installed in the experiment and ready for final commissioning and to collect data in LHC Run3, starting March 2022. The NSW is the largest phase-1 upgrade project of ATLAS. It is challenging completion and readiness for data taking is a remarkable achievement of the collaboration. The two wheels (10 meters in diameter) replace the first Muon stations in the high-rapidity regions of ATLAS and are equipped with multiple layers of two completely new detector technologies: the small strips Thin Gap Chambers (sTGC) and the Micromegas (MM). The latter belongs to the family of Micro Pattern Gaseous Detectors (MPGD, for the first time used in such a large scale in HEP experiment). Each detector will cover more than 1200 m2 of the active area. The new system is required to maintain the present detector’s efficiency and momentum resolution level in the expected higher background level, given the ongoing LHC luminosity upgrades. In addition, it is necessary to keep an acceptable Muon trigger rate with the same Muon momentum threshold.11Copyright 2022 CERN for the benefit of the ATLAS muon collaboration. Reproduction of this article or parts of it is allowed as specified in the CC-BY-4.0 license.