Development of small high-gain tubes for the electromagnetic calorimeter of the CPLEAR experiment

We have designed small rectangular cross-section tubes, 4×4.5 mm2, working in a high-gain mode. Two of the four cathode walls are coated with high-resistivity graphite, allowing the detection of the induced pulses on external strip boards. At 3.2 kV, the collected charge on the wires, which is due to a minimum-ionizing particle, is 10 pC and can be read out without preamplification. The small size of the tubes makes them particularly suitable for use in gas-sampling calorimeters.