Precision Muon Tracking Detectors and Readout Electronics for Operation at Very High Background Rates at Future Colliders 

Oliver Kortner, Hubert Kroha, Sebastian Nowak, Robert Richter, Philipp Schwegler

Max-Planck-Institut fuer Physik, Munich

The experience of the ATLAS muon spectrometer shows that drift-tube chambers provide highly reliable precision muon tracking 
over large areas. The ATLAS muon chambers are exposed to unprecedentedly high background of photons and neutrons 
induced by the proton collisions. Still higher background rates are expected at future high-energy and high-luminosity colliders beyond HL-LHC.
Drift-tube detectors with 15 mm tube diameter (30 mm in ATLAS) and improved readout electronics optimized for high rate operation
have been developed for such conditions. Tests at the Gamma Irradiation Facility at CERN showed that the rate capability 
is improved by more than an order of magnitude compared to the ATLAS chambers as space charge effects are strongly suppressed 
and operation with minimal electronics deadtime becomes possible. Studies of the new readout electronics will be discussed.
Several full-scale chambers have been constructed with unprecedentedly high sense wire positioning accuracy of better than 10 micron. 
The chamber design and assembly methods have been optimized for large-scale production, reducing considerably cost and construction 
time while maintaining the high mechanical accuracy and reliability. Precise mounting of optical sensors with respect to the sense 
wires is essential for achieving the required accuracy of the chamber alignment system and is integral part of the assembly procedure.