Charles Peyrou: 1918-2003

Charles Peyrou, who was one of the outstanding personalities at CERN for thirty years, passed away on 6 April 2003.

Born in Oloron-Sainte-Marie (France) on 18 May 1918, Charles Peyrou studied at the Ecole Polytechnique, where he attended the first class given by Louis Leprince-Ringuet in 1936. Here, he was part of the small group of enthusiastic physicists who took part in the first cosmic ray experiments. In 1938, the group built its first chamber, a large Wilson chamber in a magnetic field, operating with Geiger counters. After the war, following his appointment as chief engineer of one of the large national technical institutes known as the Corps de l'Etat, he was detached to his old laboratory to resume research on cosmic rays, and a system of two superimposed cloud chambers was set up at the Pic du Midi. This device proved very effective in the study of the strange particles that were starting to be detected at that time. Here, for example, the disintegration of the K meson into a muon and a neutrino was identified for the first time. Physicists were satisfied with about fifty "good" events a year in those days but progress was being made in the accelerator field. In Europe, the construction of CERN was underway. Charles Peyrou, who was already a senior lecturer at the Ecole Polytechnique (1946-1954), became a professor at the University of Bern (1954-1958), where he continued to give a course until 1974. Flying in the face of a certain degree of scepticism, he dedicated himself entirely to the European cause.

Having joined CERN in 1957, he championed the Laboratory's conversion to bubble chambers as head of the Bubble Chamber Group and subsequently of the Track Chamber Division in 1961, finally becoming Director of the latter's mother department, the Physics II Department, in 1966, a post he held for ten years. His deep understanding of both physics and engineering enabled him to talk to physicists and engineers with equal authority. Thanks to his generous, strong, realistic temperament, his exceptional physics intuition, his tenacity and imagination, track chamber physics experienced remarkable progress.
He directed the construction of successive hydrogen bubble chambers, starting with an initial 10 cm chamber and moving on to a 30 cm chamber in 1959, a 200 cm chamber in 1965 and finally the BEBC, a bubble chamber with a superconducting magnet, which collected over 6 million photographs. The technological impact was important, especially for cryogenics and superconductivity. In parallel, Charles Peyrou offered valuable support to the European bubble chamber user community, helping physicists to conduct their research in the institutes of CERN's various Member States.
When the time of the bubble chambers was over, he maintained an active interest in the life of CERN. He enjoyed discussing the latest physics results with young physicists. His energy, his enthusiasm for mathematics, his astounding memory and his articulacy made every encounter with him a memorable occasion. His organisational abilities and his great experience continued to benefit the whole laboratory even after his retirement.

Goodbye, Charles, and thank you.