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The latter use a Geiger-Mueller tube: a wire, carrying a high voltage, passes through a metal tube whose walls are held at ground potential. Any ionizing particle that passes through the tube causes the flow of a current. This allows the experimenter to count particles and, in the case of the proportional counter, determine their energy.

For high energy physics experiments, it is also valuable to observe the particle's path. For a long time, one used bubble chambers for this purpose, but with the improvement of electronics, it became desirable to have a detector with fast electronic read-out. (In bubble chambers, photographs were made, printed and then looked through.) A wire chamber is a chamber with many parallel wires, arranged as a grid and put on high voltage, with the metal casing being on ground potantial. As in the Geiger counter, a particle leaves a trace of ions and electrons, which drift toward the case or the nearest wire, respectively. By marking off the wires which had a pulse of current, one can see the particle's path.

An improvement is the multi-wire proportional chamber (MWPC) which combines this with the idea of the proportional counter (see there) to determine the energy. The 1968 invention of this device won Georges Charpak (then at CERN) the 1992 Nobel Prize in Physics.

Often, the chamber is put into a homogeneousHomogeneous is an adjective that has several meanings. See homogeneous (mathematics) for a number of mathematical usages Homogeneity has a precise meaning in physics. In biology homogeneous has a meaning similar to its meaning in mathematics. Generally it magnetic fieldIn physics, a magnetic field is an entity produced by moving electric charges ( electric currents) that exerts a force on other moving charges. The quantum-mechanical spin of a particle produces magnetic fields and is acted on by them as though it were a, so that chargeCharge is a word with many different meanings. Science In science, the concept of charge is derived from the observation of conserved quantum numbers. Various charge-like quantum numbers have been introduced by theories of particle physics, e. electric chd particles are led into spiralFor the album by Vangelis, see Spiral For the Soviet spaceplane, see Spiral (spaceplane For Sprials on railways, see Spiral (railway) In mathematics, a spiral is a curve which turns around some central point or axis, getting progressively closer to or far paths due to the Lorentz forceIn physics, the Lorentz force is the force exerted on a charged particle in an electromagnetic field. The particle will experience an electric force q E and a magnetic force q v × B . Combined they give the Lorentz force equation : where E is the electric. By checking the direction of the curves, one can see whether and how the particles are charged. The necessary magnetic fields are often quite strong: physicists at CERN like to tell visitors the story of how Charpak once was working on a MWPC, being so uncareful as to sit on an iron chair. He and his colleagues spent months carefully attaching thousands of thin wires. One day, he moved his chair a bit too close to the magnetic field. The magnet pulled his chair out from under him into the chamber, tearing apart all the wires and ruining the detector.

If one also precisely measures the timing of the current pulses of the wire and take into account that the ions need some time to drift to the nearest wire, one can infer the distance at which the particle passed the wire. This greatly increases the accuracy of the path reconstruction and is known as a drift chamber.