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.Comment: 4 pages, 5 figures, PIC201