Large Electron Positron, LEP, accelerator

All particle beams at CERN begin their lives in linear accelerators. But to reach high energies that physicists need, the big machines at CERN are circular.

Particle beams travel round and round gaining energy with each lap. In LEP, 3368 magnets are used to bend particle beams and keep them in orbit. Electrons and positrons move in the same ring but in opposite directions.

Inside the LEP tunnel.

At LEP, 272 accelerating cavities accelerate the particles and maintain the energy. These are made of superconducting metal and they operate at 269 degrees Celcius below freezing.

Superconducting radio frequency cavity in the LEP tunnel.