LEP - the world's largest particle accelerator

CERN, the European Laboratory for Particle Physics established 1953, is composed today of thirteen West European member countries. Its laboratories are spread over an area on both sides of the border between Switzerland and France. Roughly, 3,500 staff members design, build and maintain the particle accelerators used by more than 2,500 scientists. In 1957, the 600 MeV synchro-cyclotron was completed, in 1976 the 400 GeV proton synchrotron. In 1981, the Council of member countries approved the construction of a large 2X50 GeV electron-positron storage ring, the Large Electron-Positron Collider (LEP), which was begun on September 13, 1983. The machine is housed in a tunnel 27 km long and installed up to 160 m below ground level. Four packets each of electrons and positrons circulate in opposite directions in the ultrahigh vacuum of a closed ring-shaped tube. LEP will be installed a total of 3,328 dipole magnets, 744 quadrupole magnets, and 512 sextupole magnets. In a first stage of completion four of the resulting eight collision points will be fitted with large underground experimental halls connected through shafts with the supply buildings above ground. At this stage of expansion, the particle energy will be roughly 50 GeV, which is tantamount to 100 GeV of center-of-mass energy in a collider. At some later date the center-of-mass energy is to be raised to some 200 GeV. This will allow LEP to be used for experimental verification of the theories about the electromagnetic force and the weak nuclear force and for measurements of the parameters associated with these forces. (orig.)