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 an d restrict the area of the induced signal on strips engraved on the ca thode plane. We can thus contemplate using digital readout for these s trips and still have good position resolution, or use analog readout f or 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 effici ency for minimum ionizing particles. We have measured no gain modifica tion 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.