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. The authors 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 which illustrate the reduction, to an acceptably low level, of differential nonlinearity by specific changes in the chevron geometry, a position resolution of about 110 μm (full width at half maximum) for 5.4-keV X-rays independent of wire length, and the role played by avalanche angular localization in the position interpolation technique are presented