Langevin, Sir Hector Louis, 1826-1906, Canadian legislator, b. Quebec. A lawyer, he served in the Legislative Assembly (1857-67) and its successor, the House of Commons (1867-74, 1878-96). He was solicitor general (1964-66) for Lower Canada and postmaster (1866-67) before confederation. He succeeded Georges Étienne Cartier in 1873 as leader of the French Canadian Conservative party. After the Conservatives returned to power in 1878, he was postmaster general (1878-79) and minister of public works (1879-91). There were charges of corruption (1891) in Langevin's public works department; although acquitted of complicity, he was found guilty of negligence in office and was forced to resign. He was knighted in 1881.
Langevin, Paul, 1872-1946, French physicist and chemist. He was professor of experimental physics at the Collège de France from 1909 and at the École municipale de Physique et de Chimie, Paris, from 1904 (director from 1929); dismissed by the Vichy government in 1940, he resumed his posts in 1944. He is noted for his work on the electron theory of magnetism and for his research on sound devices for submarine detection.

The Institut Laue-Langevin, or ILL, is an internationally-financed scientific facility, situated in Grenoble, France. It is one of the world centres for research using neutrons. Founded in 1967 and honouring the physicists Max von Laue and Paul Langevin, the ILL currently provides the most intense neutron source in the world, at 1.5×1015 neutrons/cm²/s.

The high-flux research reactor produces neutrons through fission in a specially designed, compact-core fuel element. Neutron moderators cool the neutrons to useful wavelengths, which are then directed at a suite of instruments and used to probe the structure and behaviour of many forms of matter by elastic and inelastic neutron scattering, and to probe the fundamental physical properties of the neutron. Nothing goes to waste: Fission products and gamma rays produced by nuclear reactions in the reactor core are also used by specialised instruments, which forms an important part of the instrument suite.

The reactor thermal power is 58.3 MW, but this energy is not used. It is removed by exchange of heat with water from the river Drac.

The institute was founded by France and Germany, with the United Kingdom becoming the third major partner in 1973. These partner states provide, through research councils, the bulk of its funding. Six more countries have since become partners. Scientists of institutions in the member states may apply to use the ILL facilities, and may invite scientists from other countries to participate. Experimental time is allocated by a scientific council involving ILL users. The use of the facility and travel costs for researchers are paid for by the institute. Commercial use, for which a fee is charged, is not subject to the scientific council review process. Over 750 experiments are completed every year, in fields including magnetism, superconductivity, materials engineering, and the study of liquids, colloids and biological substances.

The ILL shares its site with other institutions including the European Synchrotron Radiation Facility (ESRF) and the European Molecular Biology Laboratory (EMBL). A programme of safety improvements that aim to increase seismic security about the reactor dome by removing adjoining buildings has recently been carried out. These have now been completed and neutron experiments are once again being carried out routinely on 50-day cycles at the facility.


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