THE GREAT CHALLENGE OF THE XXI CENTURY / Accelerators / How do accelerators work

The great challenge of the XXI century

What is an accelerator How do accelerators work Accelerators of CERN LHC SPS PS

How do accelerators work

In the circular accelerator, particles move in a circle until they reach sufficient energy. The particle track is typically bent into a circle using electromagnets. A number of accelerators can be joined together in sequence to reach successively higher energies, as at the accelerator complex at CERN. In the linear accelerators in a straight line where the beam travels from one end to the other.

The advantage of circular accelerators over linear accelerators (linacs) is that the ring topology allows continuous acceleration, as the particle can transit indefinitely.

Not depending on the type, the accelerators components are:

Particle source — from here come the particles ready to be accelerated. These can be electrons, protons, ions, positrons, nucleus of heavy elements etc.
Copper tubes — there travel the accelerated particles. The tube is out of copper because it is good electromagnetic conductor. Often these tubes are long kilometers.
Radiofrequency (RF) cavities and electric fields – these provide acceleration to a beam of particles. RF cavities are located intermittently along the beam pipe. Each time a beam passes the electric field in an RF cavity, some of the energy from the radio wave is transferred to the particles.
Magnets – various types of magnets are used to serve different functions. For example, dipole magnets are usually used to bend the path of a beam of particles that would otherwise travel in a straight line. The more energy a particle has, the greater the magnetic field needed to bend its path. Quadrupole magnets are used to focus a beam, gathering all the particles closer together (similar to the way that lenses are used to focus a beam of light).
Detectors — these are one of the most important parts of the accelerator. They 'see' the new formed particles and the radiation emitted in the collision.
Vacuum chamber — this is a metal pipe (also known as the beam pipe) inside which a beam of particles travels. It is kept at an ultrahigh vacuum to minimise the amount of gas present to avoid collisions between gas molecules and the particles in the beam.
Cooling systems — they are essential because copper tubes heat and may melt as well as expand.
Computer systems — they controll all the processes in the accelerator. Fitted with the best processors, these computers have lots of memory and comunicate in networs.
sPower source — accelerators consume a lot of energy. Often they are connected straight to an electricity plant or they are equipped with generators.