Positron Beam
If we want to perform an experiment where electrons
and positrons collide, how do we produce the positrons? These
are antimatter particles. There are none around -- we really
have to make them!
Positrons are produced by diverting some of the electrons from the accelerator and colliding them with a large piece of tungsten. This collision produces large numbers of electron-positron pairs. The positrons are collected and sent back along a separate line to the start of the linac.
At the beginning of the linac, magnets turn the positrons around and send then into the linac where they are accelerated in just the same way as electrons.
