The HERA-B Outer Tracker consists of drift tubes folded from polycarbonatefoil and is operated with Ar/CF4/CO2 as drift gas. The detector has to standradiation levels which are similar to LHC conditions. The first prototypesexposed to radiation in HERA-B suffered severe radiation damage due to thedevelopment of self-sustaining currents (Malter effect). In a subsequentextended R&D program major changes to the original concept for the drift tubes(surface conductivity, drift gas, production materials) have been developed andvalidated for use in harsh radiation environments. In the test program variousaging effects (like Malter currents, gain loss due to anode aging and etchingof the anode gold surface) have been observed and cures by tuning of operationparameters have been developed.
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