Georges Charpak


Georges Charpak

Georges Charpak, a French citizen, was born on August 1, 1924 in Poland. Charpak's family moved from Poland to Paris when he was seven years old. During World War II Charpak served in the resistance and was imprisoned by Vichy authorities in 1943. In 1944 he was deported to the Nazi concentration camp at Dachau, where he remained until the camp was liberated in 1945. Charpak became a French citizen in 1946. He received a Ph.D. in 1955 from the College de France, Paris, where he worked in the laboratory of Frédéric Joliot-Curie. In 1959 he joined the staff of European Laboratory for Particle Physics at CERN in Geneva and in 1984 also became Joliot-Curie professor at the School of Advanced Studies in Physics and Chemistry in Paris.

Georges Charpak received the Physics Nobel Prize for 1992 for his numerous contributions to the instrumentation used in experiments at high-energy accelerators. Many of the new particles discovered in the past few decades have used detectors developed or greatly improved by Charpak. In particular, his development of the multiwire proportional chamber in the 1960's allowed the path of particles issuing from high-energy collisions to be tracked with a spatial precision of less than 1 mm. The measured coordinates along the path of a charge particle passing through a magnetic field can be used to calculate the particle's momentum. Additionally, the rate at which the chamber could make a measurement, recover, and then be able to make a new measurement grew to be many thousands per second. These characteristics of Charpak's detector - high spatial resolution and high repetition rate - were particularly important in the study of rare interactions or the creation of short-lived exotic particles which often require the use of intense beams and the sampling of a large number of events in a short period of time.

Georges Charpak built the first multiwire proportional chamber in 1968. Unlike earlier detectors, such as the bubble chamber, which can record the tracks left by particles at the rate of only one or two per second, the multiwire chamber records up to one million tracks per second and sends the data directly to a computer for analysis. The speed and precision of the multiwire chamber and its descendants, the drift chamber and the time projection chamber, revolutionized high-energy physics. Samuel Ting's discovery of the J/psi meson and Carlo Rubbia's discovery of the W and Z particles, which won Nobel Prizes in 1976 and 1984, respectively, involved the use of multiwire chambers; and by the 1990s such detectors were at the heart of almost every experiment in particle physics. Charpak's chamber also has applications in medicine, biology, and industry.

Indeed, Charpak's work helped pave the way for a greater incorporation of computers into the data-acquisition process. At accelerators where millions of high-energy collisions per second can occur and where vast amounts of data must be processed quickly, computers are crucial. It is estimated, for example, that at the Super conducting Super Collider some 40 trillion bytes of information per second will flow out of detectors monitoring the proton-proton interactions taking place.

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