s, which physicists like to call 'Dees'.
The particles are forced into a circular path by the magnetic field; the electrodes are supplied with an alternating current that attracts and repels the particle, thus accelerating the particle. This type of accelerator is much easier to make than a few miles of linear accelerator. However, it is not perfect. As the electrodes accelerate the particles they increase the radius of their path. This means that as the need to produce a faster moving particle the larger the radius of the cyclotron has to be. This is not really a problem for the electrodes but it is a huge problem for the magnets!
With most complicated problems it is often the simplest solution that works best. The linear accelerator is very simple, and does not require a huge magnet. The problem is it has to be very long. How could there be a simple way of making it shorter and more useful? Well, make it circular. The problem with this is that you have to force the electrons into a circular path using magnets. Unlike having a single magnet providing the force to push the particle into a circular path this system requires a series of magnets positioned so as to deflect its path into a circle.
This type of accelerator again suffers the same problem as the cyclotron, yet it's problems are more easily overcome. As the particle travels faster the mass increases, and so the force needed to pull it around in a circle increases. In the synchrotron this is done by increasing the strength of electromagnets used to turn the particle. As soon as the particle is accelerated it needs the force applied to it to increase. In this case the energy required to keep the particle in a circular path instantly becomes too much for any conventional system. This is the main reason that CERN is 27 kilometres long.
Rather worryingly the largest particle accelerator in the world is not the most powerful. CERN can produce particles of 50GeV, which is fairly impressive but not as impressive as the Fermi National Accelerator Laboratory (Fermilab). Fermilab is home to the Tevatron, a particle accelerator capable of producing 1TeV. This is mainly due to the fact that all the magnets used in the accelerator are super conductive, meaning no loss of energy and interesting magnetic properties! If this was not enough the accelerator is a storage ring collider accelerator. This means two sets of particles are rotate in opposite directions around the ring, then collides the two sets of particles. This effectively means a collision of at least 2TeV will occur when two particles collide.
The science of particle accelerators and the results obtained from them are at the cutting edge of physics. The instruments used to detect particles are at least three stories high. The data they produce when particles collide is equivalent to 10,000 copies of the Encyclopaedia Britannica per second. This means mammoth computers that don't run Windows. The scientists analysing the data are so amazingly imaginative that they come up with names like 'weakon' and 'koan'. Most worryingly they have already worked out the properties of undiscovered particles.