 Multiwire proportional chamber

A multiwire proportional chamber is a proportional counter: parallel anode wires between cathodes in a gas. Charged particle ionization frees Electrons; an electric field drives them toward wires, triggering an electron avalanche read by electronic amplifiers.^[ref]

Georges Charpak's electronic readout avoided film scanning and full spark chamber discharge.^[ref]

Opposite polarities identify the avalanche wire. Positive ion motion dominates integrated signal; detection precedes complete collection. Calibrated Electron travel times enable drift chambers.^[ref]