At CERN accelerators have been built since the 1950s. Today a large system of linear and circular accelerators exists there. Several of the older accelerators are still used to start the acceleration of particles before they are sent in into the largest accelerators.
The CERN accelerator system can accelerate electrons, positrons, protons and different kinds of ions. We will here describe the process when electrons and positrons are accelerated.
Heat is used to transfer energy to a metal wire in an electrical field. The electrons in the wire then get enough energy to liberate themselves from the atoms in the wire. A linear accelerator (LIL) is then used to accelerate the liberated electrons to an energy of 200 MeV.
Some of the electrons are deflected and let to collide with a heavy metal target. These collisions create the positrons used in the accelerator system.
The linear accelerator then accelerates the electrons and the newly created positrons further to an energy of 600 MeV. There after the particles are led into a storage ring (EPA) where they are kept while accumulating more particles.