Cathode Strips

  In multiwire proportional or drift chambers, the cathode may serve a purpose beyond supplying the electric field to make the electrons drift to the sense wires: if the cathode is made of strips with their orientation perpendicular to the anode wires they give information about the second coordinate. This technique was first used by G. Charpak and F. Sauli [Charpak73]. The avalanche on the anode wire induces a signal on several cathode strips typically an order of magnitude smaller than the anode signal, depending on the anode-cathode distance. From the pulse-height distribution on the strips, using centroid finding methods, one can determine the position of the avalanche along the anode-wire with a precision of the order of 0.1 mm with strips as wide as 5 mm at an anode-cathode distance of 3.5 mm. References are [DeWinter89], [Piuz82], [Behrend81], or [Bridges81]. The centroid finding method is specifically discussed in [Radeka80].