CERN

CERN is the European Organization for Nuclear Research (Organisation Européenne pour la Recherche Nucléaire), the world's largest particle physics laboratory, situated on the border between France and Switzerland, just west of Geneva. It is also known for being the birthplace of the World Wide Web. The convention establishing it was signed on September 29, 1954. From the original 12 signatories of the CERN convention, membership has grown to the present 20 Member States.

The accelerator complex

The CERN accelerator complex has six main accelerators:

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• Two linear accelerators generating low energy particles for injection into the Proton Synchrotron. One is for protons and the other for heavy ions. These are known as Linac2 and Linac3 respectively.
• The PS Booster, which increases the energy of particles generated by the linear accelerators before they are transferred to the other accelerators.
• The 28 GeV Proton Synchrotron (PS) built 1959.
• The Super Proton Synchrotron (SPS), a 2 km diameter circular accelerator built in a tunnel, which started operation in 1971. It originally had an energy of 300 GeV (but has been upgraded several times). As well as having its own beamlines for fixed-target experiments, it has been operated as a proton-antiproton collider, and for accelerating high energy electrons and positrons which were injected into the Large Electron Positron (LEP) collider.
• Isotope Separator On-line (ISOLDE), which was used to study unstable nuclei and first commissioned in 1967. Particles are initially accelerated in the PS Booster before entering ISOLDE.