The LEP ring at CERN is 3.8 metres wide and has a circumference of 26.6589 kilometres. It is situated at Meyrin near Geneva in Switzerland. About 100 m below ground, the tunnel circles under the foothills of the Jura mountain range and out past the French border. There are 4600 magnets, used to guide the bunches of electrons and positrons round the ring. The particles are accelerated by radio waves in hollow cavities made of copper at two points on the ring, they travel round the ring inside a narrow aluminium pipe within which there is a vacuum to prevent collisions with air molecules etc. that would cause collisions and disrupt the trajectory of the particles. The LEP ring has to be so big because the particles radiate energy as they travel in a curved path, and the aim is to minimise this radiation energy loss. Higher energies mimic the Universe at earlier stages, closer to the Big Bang, and mean that a wider variety of particles can be produced.
Click Here to see an Interactive Display of LEP Events