Studies on Ageing and Reanimation of Drift Tubes for the ATLAS Muon Spectrometer

The drift tubes of the ATLAS muon spectrometer are expected to accumulate charges of up to 0.6 C/cm wire during ten years of operation. Five drift gases were developed for the drift tubes and tested in various ageing setups. The influence of the drift gas on the ageing performance was studied. Also the gas flow, additives to the drift gas, cathode coating, cathode cleanliness, irradiation rate and high voltage were varied to determine their influence on the ageing performance. Furthermore, a technique for reanimation of inefficient drift tubes was developed, which enables safe reanimation of drift tubes with minimal effort. This technique is also suitable for cathode cleaning and noise curing.