Characterization studies of small-strip Thin Gap Chambers for the ATLAS Upgrade

The luminosity of the Large Hadron Collider (LHC) at the CERN laboratory will reach up to $\mathcal{L} = 5 × 10^{34}$ cm$^{-2}$ s$^{-1}$ following a series of upgrades planned over the next decade. The increased luminosity puts a high pressure on the acquisition systems of the LHC particle physics experiments. In order to fully benefit from the increased LHC luminosity, the ATLAS detector, one of the LHC particle physics experiments, will be upgraded during the LHC Long Shutdown 2 beginning in 2019. Some parts of the ATLAS muon detector system will be replaced to reduce the single lepton trigger rate without raising the transverse momentum thresholds. Half of the newly installed detectors are small-strip Thin Gap Chambers (sTGC), a variant of the current ATLAS TGC technology with improved tracking capabilities. A simulation of a set of sTGC detector modules in ATLAS is performed to certify that the manufacturing process and the detector tech- nology are adequate to deliver the performance requirements for the ATLAS upgrade. Measurements of sTGC spatial resolution using cosmic rays and in a test-beam setup are presented. The cosmic-ray measurements are performed in-situ using novel techniques to correct for detector planes misalignments and detector effects. A certification procedure for the quality control of sTGC modules was developed. Results of the procedure with a sTGC prototype are shown as a proof of concept.