Delay line readout of a large dimension multi-wire proportional chamber

A two dimensional multi-wire proportional chamber with delay line readout was developed, which has a large sensitive area of 30 cmx30 cm. Two cathode planes using printed circuit boards are orthogonally placed to give two coordinates of the impact point of the particle. Signals collected from the cathode strips are amplified and discriminated from two ends of the delay line at each cathode board. By recording the time difference between the two discrimination pulses and the common gate pulse from anode wires, a coordinate position was reconstructed, and a position resolution of better than 1 mm could be obtained in the whole sensitive area along the anode wires.