Performance of Michigan sMDT prototype chambers for the HL-LHC ATLAS muon detector upgrade

Abstract A new small-diameter Monitored Drift Tube (sMDT) chamber has been developed for the muon spectrometer of ATLAS experiment to handle higher collision rates expected at CERN High Luminosity Large Hadron Collider (HL-LHC). This paper presents measurements tracking resolution and hit efficiency two prototype sMDT chambers constructed University Michigan. Using cosmic-ray muons 103.7 ± 8.1 ?m was measured one 101.8 7.8 other, compared with a design 106 ?m. further improvement 83.4 obtained by using high-gain readout electronics which will be added HL-LHC. An average (98.5 0.2)% found both chambers. The methodology used determine detector efficiency, including reconstruction data Geant4 simulation test chamber, is presented in detail.