High-precision spectroscopy with the ATLAS muon system

The ATLAS muon spectrometer will measure muon tracks along a spectrometer arm of up to 15 m length, embedded in a magnetic field of ∼0.5 T. The precision tracking devices in the muon system will be high-pressure drift tubes (MDTs). To achieve a momentum resolution of ∼10% for muons with a transverse momentum of pT=1 TeV/c, the systematic error to the space–time relationship has to be smaller than δr.m.s.<70 μm. Contributions to a systematic error δr.m.s. and its impact on the muon-momentum resolution are discussed. LHC physics require excellent knowledge of the absolute momentum scale. We show a calibration method which will achieve an accuracy at the 10−4 level.