The layout of the Large Hadron Collider
21 July 1999
The Large Hadron Collider (LHC), which is being built at CERN, the European Laboratory for Particle Physics, will collide particle beams head on at higher energies than ever before. The beams will travel millions of times round the 27-km circular tunnel that currently houses the Large Electron Positron (LEP) collider. The tunnel lies on average 100 m below ground - greatly exaggerated in this diagram - between Lake Geneva (left) and the Jura mountains (right). Four experiments will detect the head-on collisions, down at the level of the LHC tunnel. ATLAS and CMS will study many aspects of collisions between protons, while LHC-b will pick out collisions where particles B-particles are produced, in order to study tiny differences between matter and antimatter. For ALICE, the LHC will change from protons to much heavier particles - the nuclei of lead atoms, with 208 protons and neutrons altogether - in an attempt to study the formation of the "quark-gluon plasma" that is expected in very high energy collisions. The diagram also shows the ring of the Super Proton Synchroton (SPS), which will the feed the LHC both with protons beams and with lead beams.
Credit: CERN Photo
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