A HIGH-RATE, HIGH-RESOLUTION ASYMMETRIC WIRE CHAMBER WITH MICROSTRIP READOUT

We have investigated the properties of an asymmetric wire chamber with cathode strip readout. The use of a small gap between the anode plane and the cathode plane and of an electric field configuration provide fast removal of the positive ions produced in the avalanche process and restrict the area of the induced signal on strips engraved on the cathode plane. We can thus contemplate using digital readout for these strips and still have good position resolution, or use analog readout for high spatial resolution. The detector can operate at very high gas gain (10(5)); thus with a small gap of 2 mm we can achieve full efficiency for minimum ionizing particles. We have measured no gain modification at a rate of 2 X 10(5) particles mm-2 s-1 at a gain of 10(4) with a distance of 600 mum between anodes and cathodes and 500 mum between anode and cathode field wires.