Muon Spectrometer Phase-I Upgrade for the ATLAS Experiment: the New Small Wheel project

TL;DR

The ATLAS Muon Spectrometer is being upgraded with New Small Wheels combining Micromegas and sTGC technologies to handle increased LHC luminosity, improving detection and background rejection in the forward region.

Contribution

This paper presents the design, implementation, and production status of the New Small Wheel upgrade for the ATLAS muon spectrometer, integrating two detector technologies.

Findings

Successful design choices addressing physics needs.

Progress in detector module production.

Enhanced detection capabilities expected.

Abstract

The instantaneous luminosity of the Large Hadron Collider at CERN will be increased by up to a factor of five to seven with respect to the design value. To maintain an excellent detection and background rejection capability in the forward region of the ATLAS detector, part of the muon detection system will be upgraded during LHC shutdown periods with the replacement of part of the present first station in the forward regions with the so-called New Small Wheels (NSWs). The NSWs will have a diameter of approximately 10 m and will be made of two detector technologies: Micromegas and small-strip Thin Gap Chambers (sTGC). The physics motivation for this significant upgrade to the ATLAS detector will be presented. The design choices made to address the physics needs will be discussed. Finally, the status of the production of the detector modules will be presented.