Multi-wire proportional chamber

From the early 20th century onwards, a number of experimental apparatuses were developed by physicists to detect new particles. The principle of these apparatuses is to observe not the object itself but the trace it leaves in its path. In 1912 the Wilson cloud chamber enabled the trace of particles to be followed by the ionisation* of a gas. Following bubble then spark chambers, and with progress in electronics, Charpak’s multi-wire proportional chamber marked a prodigious leap forward in the number of events it could analyse. The chamber consists of a network of very thin wires under high voltage, two millimetres apart. The passage of a particle near a wire is detected and localised by electrical impulses produced on that wire and proportional to the energy of the particles. Particle detectors with enormous wire chambers (100 square metres) have enabled the observation of new elementary particles such as bosons and quarks. Georges Charpak was awarded the Nobel Prize for Physics in 1992 for this invention.