Development of precision drift tube

Detectors at the Large Hadron Collider (LHC) at CERN are designed to withstand unprecedentedly high background rates. At the LHC design luminosity of 1034 cm2s-1, the Muon Drift Tube chambers of the ATLAS muon spectrometer have to cope with neutron and gamma ray background rates of up to 500 Hz/cm2 in the inner and middle chamber layers in the forward regions of the detector. At the super-LHC, the high luminosity upgrade of the LHC, the background rates are expected to increase by an order of magnitude. The resulting high occupancies lead to a significant deterioration of the muon detection efficiency compromising the physics goals. The ATLAS muon spectrometer is instrumented with three layers of precision tracking detectors each consisting of 6 or 8 layers of pressurized aluminum drift tubes of 30 mm diameter. The possibility to improve the muon detection efficiency at the Super-LHC by reducing the diameter of the drift tubes has been investigated. We report about the design and test results of prototype drift-tube detectors with thin-walled aluminum tubes of 15 mm diameter