Investigation of Chevron Cathode Pads for Position Encoding in Very High Rate, Gas Proportional Chambers*

New techniques for position encoding in very high rate particle and photon detectors will be required in experiments planned for future particle accelerators such as the Superconducting Super Collider and new, high intensity, synchrotron sources. We are carrying out a detailed theoretical and experimental study of a position interpolation technique in which a row of chevron shaped cathode pads lies underneath each anode wire of a proportional chamber. Centroid finding of the cathode induced charge is performed on the signals from the chevron pads. High event rate and high multiplicity capabilities are achieved by parallel readout. Results are presented which illustrate the reduction, to an acceptably low level, of differential non-linearity by specific changes in the chevron geometry, position resolution of about 110μm (FWHM) for 5.4 keV X-rays independent of wire length, and the role played by avalanche angular localization in the position interpolation technique.