HADES tracking system: first in-beam experience

The high acceptance di-electron spectrometer at the GSI, Darmstadt, Germany, heavy-ion synchrotron Schwerionen Synchrotron is a high-resolution second-generation detector system for lepton pair spectroscopy. Its low-mass tracking system consists of two pairs of planes of trapezoidally shaped multiwire drift chambers, installed on either side of a superconducting toroidal magnet. This paper summarizes our experience with the construction and in-beam operation of the six large-area chambers produced by Forschungszentrum Rossendorf. Studies on creeping of aluminum wires over a period of three years are presented. In addition, the observation of the growth of filaments with various shapes and sizes in one of the chambers used in-beam will be discussed in detail.