Digitizing Electronics for the EMI Multi-Wire Proportional Chambers

A complete system of electronics for digitizing pulses from a large array of multi-wire proportional counters is described. The system is based on the method of coupling the chamber pulses onto delay lines developed by Perez-Mendez. All three wire planes of each chamber are digitized, giving positional information for each avalanche in the chamber on three coordinates, x, y and a redundant coordinate. The system will be used with an array of 30 ch-iambers each one meter square, which will serve as an External Muon Identifier (EMI) for the 15-foot diameter bubble chamber in the neutrino beam line at NAL. Up to 16 events can be digitized in a 60 us beam spill.