Lorentz angle studies for the SLD endcap Cherenkov Ring Imaging detector

Abstract In the endcaps of the Cherenkov Ring Imaging Detectors for SLD, photoelectrons drift under the influence of crossed electric and magnetic fields. The geometry of the encap design is closely coupled to the Lorentz angle in the chosen drift gas. In this report, we present recent measurements of Lorentz angles and drift velocities in gases suitable for the CRID photon detectors. We compare these measurements to predictions from a theoretical model; good agreement is observed. Based on our results we present a design for detectors operating in a 0.6 T transverse magnetic field.