# The Micromegas Project for the ATLAS New Small Wheel

## TL;DR

The MicroMegas project for the ATLAS Small Wheel upgrade introduces advanced detector technology to improve muon tracking and trigger capabilities in high-radiation environments at the LHC.

## Contribution

It presents the design, construction, and assembly of MicroMegas modules tailored for the ATLAS New Small Wheel upgrade, meeting specific spatial resolution and rate requirements.

## Key findings

- Achieved spatial resolution of 100 μm in MicroMegas chambers
- Demonstrated operation in high background radiation environments
- Ensured compatibility with magnetic fields up to 0.3 T

## Abstract

The MicroMegas technology was selected by the ATLAS experiment at CERN to be adopted for the Small Wheel upgrade of the Muon Spectrometer, dedicated to precision tracking, in order to meet the requirements of the upcoming luminosity upgrade of the Large Hadron Collider. A large surface of the forward regions of the Muon Spectrometer will be equipped with 8 layers of MicroMegas modules forming a total active area of $1200\,m^{2}$. The New Small Wheel is scheduled to be installed in the forward region of $1.3<\vert \eta \vert <2.7$ of the ATLAS detector during the second long shutdown of the Large Hadron Collider. The New Small Wheel will have to operate in a high background radiation environment, while reconstructing muon tracks as well as furnishing information for the Level-1 trigger. The project requires fully efficient MicroMegas chambers with spatial resolution down to $100\,{\mu}m$, a rate capability up to about $15\,kHz/cm^{2}$ and operation in a moderate (highly inhomogeneous) magnetic field up to $B=0.3\,T$. The required tracking is linked to the intrinsic spatial resolution in combination with the demanding mechanical accuracy. An overview of the design, construction and assembly procedures of the MicroMegas modules will be reported.