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 determined to be valid for the entire ATLAS Run 2. The final single-hit spatial resolution, averaged over 1172 monitored drift tube chambers, is 81.7 ± 2.2 μm.
Highlights
To cite this article: The ATLAS collaboration 2019 JINST 14 P09011 View the article online for updates and enhancements
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
This paper describes the algorithms which generate a pair of correction parameters for the t0 offsets and the R(t) functions
Summary
The ATLAS experiment [5] at the LHC is a multipurpose particle detector with a forward-backward symmetric cylindrical geometry and a near 4π coverage in solid angle. It consists of an inner tracking detector (ID) surrounded by a thin superconducting solenoid providing a 2 T axial magnetic field, electromagnetic and hadronic calorimeters, and a muon spectrometer. The ATLAS experiment [5] at the LHC is a multipurpose particle detector with a forward-backward symmetric cylindrical geometry and a near 4π coverage in solid angle.1 It consists of an inner tracking detector (ID) surrounded by a thin superconducting solenoid providing a 2 T axial magnetic field, electromagnetic and hadronic calorimeters, and a muon spectrometer. A fourth annulus of endcap chambers covers a limited pseudorapidity region spanning from the barrel to the endcap They are constructed of pairs of close-packed multilayers of 3 cm diameter cylindrical aluminum drift tubes, 1 m to 6 m long for the inner stations close to the beam and outer stations, respectively. These first-level triggers are followed by more refined software-based triggers that reduce the accepted event rate to 1 kHz on average
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