André Blanc-Lapierre, one of the most distinguished members of the French scientific community, died from a stroke on 14 December 2001 in Châtenay-Malabry, France.
Blanc-Lapierre was born on 7 July 1915 in Lavaur, France. After graduating from the Ecole Normale Supérieure, he joined the physics laboratory of that institution in 1940 to prepare a thesis under Georges Bruhat’s supervision. His doctoral dissertation, completed in 1944, was devoted to the study of the shot noise and its influence on the measurement and amplification of very small photocurrents.
In the 1940s, the origin of the shot noise and its theoretical description were not at all understood. Blanc-Lapierre was the first to realize that proceeding beyond a qualitative description of random phenomena required the tools provided by probability theory. Although the theoretical foundations of probability theory were known, the concept of stochastic processes—fundamental for describing physical phenomena—was not. Blanc-Lapierre analyzed this concept in another thesis defended in mathematics in 1945. It is exceptional in France for anyone to have doctorates in two different fields. The work done for those two doctorates was the starting point of a series of papers devoted to stochastic processes applied to various domains of physics and information sciences. A synthesis of the results presented in those papers became the subject matter of the book Théorie des Fonctions Aléatoires (Masson, 1953), with coauthor Robert Fortet, that, by its clarity and depth, was a revelation to many researchers working in this domain.
In 1947, Blanc-Lapierre was appointed as a professor of physics at the University of Algiers, where he founded a laboratory for theoretical physics. During the next decade, he extended his field of interest considerably by encouraging and advising young physicists to explore new areas of application for probabilistic methods. Among his many developments was his suggestion that ideas known in radioelectricity were applicable to optics. He was the first to show that the concept of coherence in optics must be described by using appropriate correlation functions. His paper with Pierre Dumontet, published in French in 1954, was not well known. This concept became clear only 10 years later with the development of lasers and coherent optics.
Because of his talent as a manager, Blanc-Lapierre was asked to head the Laboratoire de l’Accélérateur Linéaire (LAL) at Orsay in 1961. He succeeded Hans Halban, who had just resigned. During the eight years Blanc-Lapierre directed LAL, the laboratory grew in a remarkable way. Blanc-Lapierre decided to upgrade the electron linac energy from 1 GeV to 2.3 GeV to accommodate K meson experiments. In addition, a positron beam was set up at the lab—a facility that proved to be crucial for the storage rings to come.
Following a recommendation by Pierre Marin, Blanc-Lapierre also launched a new program focusing on electron–positron storage rings. He proposed to the Italian team that had built the electron–positron prototype ring AdA in Frascati to bring the ring to Orsay to benefit from the intense linac beam. The transfer occurred in 1962; two years later, electron–positron collisions were observed in AdA for the first time ever in a storage ring. Furthermore, he asked a team of engineers and physicists from LAL and the French Atomic Energy Commission (CEA) in Saclay to design another storage ring, called ACO, which was the first to operate with a separated function guide field. The success of this project led Blanc-Lapierre to organize (in 1966) the first international symposium entirely devoted to electron–positron storage rings.
In 1964, Blanc-Lapierre invited a group of bubble-chamber physicists to move to LAL; this group, led by André Lagarrigue, had been working at the Ecole Polytechnique. Then, jointly with the Ecole Polytechnique, the CEA, and CERN, LAL participated in the Gargamelle bubble-chamber program led by Lagarrigue. The heavy-liquid chamber turned out to be most effective in exploring neutrino interactions and eventually allowed for the famous discovery of neutral currents in 1973.
Blanc-Lapierre played an important role as an adviser to the French government in the 1960s. He later served as president of the Academy of Sciences in France (1985–86).
He retired from his professorship in 1983. During subsequent years, he remained a very active member of the French Academy of Sciences. As such, he made major contributions to the reform of the academy; in particular, he developed its relationship with the industrial world. He was instrumental in the creation of a new academy in France, the Académie des Technologies, which is somewhat analogous to the National Academy of Engineering in the US.
Blanc-Lapierre was a warm and open-minded man. Aside from the importance of his scientific legacy, he inspired admiration. He had a positive demeanor and was highly enthusiastic. He was a tireless worker who took on countless responsibilities, yet was available to his collaborators. He possessed a great aptitude for communicating and managed to handle matters in a clear and efficient way. Those who had had the privilege and the pleasure of working with him will realize, with the passing of time, how much they owe him.
