Limits to drift chamber performance at LHC luminosities

Muon spectrometers of the Large Hadron Collider experiments such as ATLAS and CMS have to operate at count rates up to 1 kHz/cm2. The ATLAS muon spectrometer physics requires a momentum resolution of ∼10% for muons with a transverse momentum of pT=1 TeV/c. This translates into a spatial resolution of σ̄=80 μm for a single-tube measurement and a systematic error to the space–time relationship due to changes of the environmental parameters of smaller than δrr.m.s<70 μm. We discuss measurements and simulations to demonstrate that even in this high-rate environment a spatial resolution of σ̄<80 μm can be achieved. Space-charge effects and contributions due to signal processing which deteriorate the resolution at high rates have been identified. The impact of changes of the environmental parameters on the space–time relationship is investigated and ways to correct for systematic errors are introduced.