Simultaneous track reconstruction and electron identification in the H1 radial drift chambers

Results of prototype tests of the radial-wire drift chambers of the H1 forward track detector are presented. Choice of a suitable gas mixture and careful design of the chambers to include the possibility of efficient X-ray detection have shown that tracks can be reconstructed with good accuracy (σ ≈ 110–150 μm) and that simultaneously electron identification can be achieved by pulse integral analysis of ionization energy deposition due to both dE/dx and transition radiation. For 90% electron acceptance the pion contamination is 8% at high momentum (≈ 60 GeV/c). At lower momenta, electron identification is further enhanced by the multiple sampling of pulse integrals in such chambers, resulting at 5 GeV/c in a pion contamination of ≈ 0.5%.