Abstract
The momentum measurement capability of the ATLAS muon spectrometer relies fundamentally
on the intrinsic single-hit spatial resolution of the monitored drift tube precision tracking
chambers. Optimal resolution is achieved with a dedicated calibration program that addresses
the specific operating conditions of the 354 000 high-pressure drift tubes in the spectrometer.
The calibrations consist of a set of timing offsets and drift time to drift distance transfer
relations, and result in chamber resolution functions. This paper describes novel algorithms to
obtain precision calibrations from data collected by ATLAS in LHC Run 2 and from a gas
monitoring chamber, deployed in a dedicated gas facility.
The algorithm output consists of a pair of correction constants per chamber which are applied to
baseline calibrations, and which have been determined for ATLAS Run 2. The final single-hit
spatial resolution, averaged over 1172 monitored drift tube chambers, is 81.7 ± 2.2 µm.