Circular accelerators

All of CERN's particle beams begin their lives in linacs, but to reach the energies that physicists need would require extremely long accelerators. For this reason, CERN's big machines are circular.

Circular accelerators work by whirling particles round and round in a circle, giving them more and more energy with each lap. Powerful magnets keep the particles moving in a circle, whilst electric fields provide the accelerating power. There are many types of circular accelerators, and since the early thirties they have played a decisive role in particle physics from the lowest to the highest energies.

In 1931, the American physicist Ernest O. Lawrence and his student Stanley Livingston built the first circular particle accelerator: the cyclotron. Things have come a long way since then - CERN's Large Electron Positron collider, the most powerful accelerator at the laboratory today, is some two million times more powerful than Lawrence and Livingstone's cyclotron.