COMMENt Obituary Georges Charpak (1924-2010) Physicist who transformed the measurement of high-energy particles. S hysicist and campaigner, past few decades have used detec- i B or

Georges Charpak has tors developed or greatly improved c / left an enduring mark on by Charpak and his team. A Pscience, technology and education. From the moment Charpak His invention of a type of particle began working on detectors, he detector — the multiwire propor- was interested in the their medi-

tional chamber — revolutionized the cal applications. Although a long- Brucelle/Sygm A. collection of data from high-energy time proponent of nuclear energy, physics experiments. The device he was horrified by the radiation allowed physicists to detect new doses that children were exposed to particles and so test fundamental during routine medical X-rays. He theories about the nature of matter. helped co-found several companies Modern variants of the detector are that applied his multiwire detectors still used in high-energy particle to medical imaging, to reduce the accelerators. exposure of patients to radioactive Charpak, who died on 29 Sep- tracers. He also worked closely with tember, was born in eastern Poland surgeons and radiologists to bring to a poor Jewish family. When he was seven, gas-filled box containing a large number these techniques to clinical settings. the family moved to Paris, lured by France’s of parallel detector wires, each connected Influenced by his experiences in wartime healthier economy. After France surren- to individual amplifiers. It recorded the Europe, Charpak’s deep concern for social dered to Germany in 1940, Charpak refused electronic pulses resulting from charged issues led him to apply his knowledge to to wear the yellow Star of David, required particles passing through the gas. These sig- education. In 1996 he created La main à la by Nazi authorities to identify Jews, and he nals could be fed directly into a computer, pâte, an organization that introduced hands- became active in the French Resistance. He increasing the detection rate of particles a on science education in primary schools in was imprisoned by the Vichy government thousand-fold. France. He got the idea from his old colleague of France in 1943 before being transferred Others had attempted to invent a similar Lederman, who had introduced a similar to the Dachau concentration camp in 1944. device but without success — largely because physics education programme in Chicago a He survived because the German guards did it was unclear what was producing the elec- few years earlier. La main à la pâte has now not realize that their political prisoner was tronic signals in the wires. Working with spread from France to other countries. actually Jewish. similar detectors in the Collège de France, In 2001, he and nuclear physicist Richard After the war, Charpak became a French Charpak realized that the electronic pulses Garwin argued in their book Megawatts and citizen. In 1954, he received his doctorate in were produced not by drifting electrons but Megatons: a Turning Point in the Nuclear Age? nuclear physics from the Collège de France rather by positive ions, which induced pulses that nuclear energy could provide an assured, in Paris where he studied in the laboratory of of opposite polarity in the wires. This dis- economically feasible and environmentally the Nobel laureate Frédéric Joliot-Curie. He covery led him to make large flat detectors sustainable supply of energy without driv- devoted his early career to nuclear physics containing several wires. Charpak’s insight ing weapons proliferation. Three years later, before switching to high-energy particle phys- meant the position of a particle could be Charpak and Henri Broch co-authored ics under the guidance of Leon Lederman at tracked with unprecedented precision. Debunked! ESP, Telekinesis, and other Pseudo­ CERN, Europe’s particle-physics laboratory science, in which they dismantled claims from near Geneva, Switzerland. Belated prize parapsychology and astrology. In 1968, while still at CERN, but by then The speed and precision of the multiwire Georges disliked the new generation of digital leading a small research group of his own, chamber and its descendants, the drift cham- detector devices. When he came to visit my Charpak developed the multiwire propor- ber and the time projection chamber, have laboratory at Saclay, he’d use an old instru- tional chamber. allowed physicists to operate experiments at ment that we kept especially for him. He was When high-energy collisions occur much higher particle collision rates and so excited, however, by a new radon detector he between particles in an accelerator, they test new theories about the nature of matter. was developing. Indeed, he believed that this generate new charged particles that ionize the In recognition of the importance of his work detector would have enough industrial suc- detector gas, leaving behind a trail of elec- on this and other detectors, Charpak was cess to allow him to “buy a new pair of shoes”. trons and positive ions. Early detectors, such awarded the Nobel Prize in Physics in 1992. Georges will be remembered as a humanist, as the bubble chamber, worked by taking pho- Years before Charpak received his prize, an enthusiast, an optimist — and someone tographs of the tracks left by these charged Nobels were awarded to physicists Samuel always open to new ideas. ■ particles moving through a medium (often Ting and Carlo Rubbia, for their discoveries liquid hydrogen in the case of the bubble of the J/ψ particle, and the heavy W and Z par- Ioannis Giomataris is research director at chamber). Yet such devices could generate ticles, respectively. Both scientists made their CEA­Saclay 91191 Gif­sur­Yvette Cedex. only a few photographs per second. findings using multiwire chambers. Indeed, France. Charpak’s multiwire chamber was a many of the new particles discovered in the e­mail: ioanis.giomataris@cern.ch

1048 | NATURE | VOL 467 | 28 OCTObER 2010 © 2010 Macmillan Publishers Limited. All rights reserved