Performance of the SLD central drift chamber

Abstract

The central drift chamber (CDC) of the Stanford Linear Collider Large Detector (SLD) 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 multiple scattering and 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 μm in the region of uniform field. Analysis of the full drift-pulse waveform allows for efficient double-hit resolution of about 1 mm. Transverse momentum resolution is given by the formula ( σ(p t ) p t 2 ) 2 = 0.0050 2 + ( 0.010 p t ) 2 , where p t is in GeV/ c. Used in conjunction with the SLD vertex detector, the CDC permits measurements of impact parameters of high-momentum tracks to 10 μm in the r- φ plane and 36 μm in the r- z plane.