Performance of the SLD Central Drift Chamber

Abstract

We report for the first time on the performance of the Central Drift Chamber (CDC) of the Stanford Linear Collider Large Detector (SLD), which has been recording data since 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 data, and report on the resolutions achieved thus far. We measure an intrinsic drift resolution of 55-110 /spl mu/m in the region of uniform field. 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/sub t//p/sub t//sup 2/)/sup 2/=0.0050/sup 2/+(0.010/p/sub t/)/sup 2/, where p/sub t/ is expressed in units of GeV/c. Used in conjunction with the SLD vertex detector, the CDC permits measurements of impact parameters of high-momentum tracks to the level of 10 /spl mu/m in the r-/spl phi/ plane and 36 /spl mu/m in the r-z plane. A resolution of 6.4% is achieved in the measurement of dE/dx for the electrons in Bhabha scattering events. >