Development of the cerenkov ring imaging detector for the SLD

Results of recent beam tests of a physics prototype cerenkov Ring Imaging Detector (CRID) for the SLD are reported. The system includes both liquid (C 6 F 14 ) and gas (isobutane) radiators and an 80 cm quartz TPC with a gaseous TMAE photocathode and proportional wire readout. Measurements of the quality factor (N 0 ) and cerenkov angles of both radiators at various TMAE concentrations and beam momenta are presented. Other system characteristics, including electron lifetimes, spatial resolution, "photon feedback" and preliminary results from third coordinate charge division readout are discussed.