FERMI NATIONAL ACCELERATOR LABORATORY

also called Fermilab, centre for particle-physics research located at Batavia, Ill., U.S., about 27 miles (43 km) west of Chicago. The facility is operated for the United States Department of Energy by the Universities Research Association, a consortium of American and Canadian institutions. The major components of Fermilab are two large particle accelerators called proton synchrotrons, configured in the form of a ring with a circumference of 6.3 km (3.9 miles). The first, which went into operation in 1972, is capable of accelerating particles to 400 billion electron volts (GeV). The second, called the Tevatron, is installed below the first and incorporates more powerful superconducting magnets; it can accelerate particles to 1 trillion electron volts (TeV). The older instrument, operating at lower energy levels, now is used as an injector for the Tevatron. The high-energy beams of particles (notably muons and neutrinos) produced at the laboratory have been used to study the structure of protons in terms of their most fundamental components, the quarks. In 1977 a team led by Leon Lederman discovered the upsilon meson, which revealed the existence of the bottom quark and its accompanying antiquark. Since 1987 the Tevatron also has operated as a proton-antiproton collider and can achieve total collision energies of 2 TeV. Antiprotons are produced and stored in a smaller ring before being injected into the main rings for acceleration and collision with protons circulating in the opposite direction. Christine Sutton