The world's largest "microscope"
3 March 1999
This aerial view of the area north-west of Geneva, Switzerland, shows the path of the world's largest "microscope" for studying the fundamental nature of matter, localted at CERN, the European Laboratory for Particle Physics. The white circle marks where the 27-km tunnel for LEP (the Large Eelectron Positron collider) passes under the countryside. Geneva airport is clearly visible in the foreground, while the Jura mountains nestle under clouds in the background. The dotted line (clearer on the larger image here) is the border between France (to the north) and Switzerland (to the south). The main CERN site is just to the left of the circle (at about 9 o'clock).
LEP collides beams of electrons with their antiparticles, positrons, at the heart of large detectors located at the positions indicated by the four white spots. (Working clockwise from the top, the detectors are ALEPH, OPAL, DELPHI and L3). After 2000, LEP will be replaced by a new machine, the LHC (Large Hadron Collider) which will reach far higher energies by colliding counter-rotating beams of protons. The LHC will be built in the same tunnel, once LEP has been removed. After its start-up, scheduled for 2005, it will be the world's highest energy particle accelerator.
Credit: CERN Photo
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