A drift chamber is an apparatus for measuring the space coordinates of the trajectory of a charged particle. This is achieved by detecting the ionization electrons produced by the charged particle in the gas of the chamber and by measuring their drift times and arrival positions on sensitive electrodes. When the multiwire proportional chamber, or ‘Charpak chamber’ as we used to call it, was introduced in 1968, its authors had already noted that the time of a signal could be useful for a coordinate determination, and rst studies with a drift ch- ber were made by Bressani, Charpak, Rahm and Zupanci c in 1969. When the rst operational drift-chamber system with electric circuitry and readout was built by Walenta, Heintze and Schurlein ¨ in 1971, a new instrument for particle experiments had appeared. A broad study of the behaviour of drifting electrons in gases began in laboratories where there was interest in the detection of particles.
