Performance of the SLD Central Drift Chamber

We reportfor thefirsttimeon theperformanceof theSLD Central Drift Chamber (CDC) at SLC, which has been recordingdatasince 1992. The low mass of the chamber and the use-of a gas characterized by both a low drift velocity and low diffusion constant help to minimize the drift-distance measurement errors. We describe some of the calibrations and corrections applied to the dam, and report on the resolutions achlevd tius far. We measure an intrinsic drift resolution of 55-110 pm in the region of uniform fiefd. ” Analysis of the full drift-pulse waveform allows for efficient double-hit resolution of about 1 mm. Momentum resolution is characterized by the formula (dp~pt2)~ 0.00502+ (0.010/pt)2. Used in conjunction with the SLD vertex det~tor, the CDC permits measurements of impact parameters of high-momentum tracks to the level of 10 pm in the r-~ plane and 36 ~m in the r-z plane. A resolution of 6.4% is achieved in the measurement of dE/dx for the electrons “inBhabha scattering events.