Muon Performance in the Presence of High Pile-up in ATLAS

TL;DR

This paper evaluates the performance of muon detection in the ATLAS experiment under high pile-up conditions at the LHC, demonstrating that muon identification and resolution remain stable despite increased collision rates.

Contribution

It provides an analysis showing muon reconstruction efficiency and momentum resolution are unaffected by high pile-up, using Z boson decays as a benchmark.

Findings

Muon momentum resolution remains stable with increased pile-up.

Muon identification efficiency is independent of pile-up levels.

Reconstruction performance is consistent across a range of transverse momenta.

Abstract

In 2012, the LHC is operated at sqrt(s) = 8 TeV in a mode leading up to 40 inelastic pp collisions per bunch crossing. The identification and reconstruction of muons produced in hard collisions is difficult in this challenging environment. Di-muon decays of Z bosons have been used to study the muon momentum resolution as well as the muon identification and reconstruction efficiencies of the ATLAS detector as a function of the muon transverse momentum from 15 GeV to 100 GeV and the number of inelastic collisions per event. These studies show that the muon momentum resolution, muon identification and reconstruction efficiencies are independent of the amount of pile-up present in an event.