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Electric fields spaced around the accelerator switch from positive to negative at a given frequency, creating radio waves that accelerate particle in bunches. Particle can be directed at a fixed target, such as a thin piece of metal foil, or two beams of particle can be collided. Particle detector record and reveal the particles and radiation tat are produced by the collision between a beam of particles and the target.

Electrons accelerate when placed in an electric field (E). An electron placed between a negatively charged cathode and positively charged anode will feel a force F=qE (electric force). A particle with mass m to which a force is applied will have an acceleration a=F/m, therefore a particle in an electric field will experience an acceleration a=qE/m.

When a charged particle (such as a proton or electron) travels through a magnetic field (B) at a speed v, it has a momentum p=mv and it feels a force F=qvB (Lorentz force). Unlike the force created by an electric field, the force created by a magnetic field is perpendicular to the direction of travel, therefore the particle changes its direction (but not its speed).

Particles travel down a long, straight track and collide with the target. Linear accelerator imparts a series of relatively small increases in energy to subatomic particles as they pass through a sequence of alternating electric fields set up in a linear structure. The small accelerations add together to give the particles a greater energy than could be achieved by the voltage used in one section alone. In a linear accelerator, the particles see the accelerating field only once, and the particles that didn’t interact are lost. As such, a linear accelerator will have much lower overall luminosity (each time, you need to produce new particles to be accelerated) and will generally not be able to reach the same energies.

The cyclotron principle involves using an electric field to accelerate charged particles across a gap between two "D-shaped" magnetic field regions. The magnetic field accelerates the particles in a semicircle, during which time the electric field is reversed in polarity to accelerate the charge particle again as it moves across the gap in the opposite direction. In this way a moderate electric field can accelerate charges to a high energy.

Synchrotron is a cyclic particles accelerator in which a charged particles are accelerated to very high energies in the presence of an alternating electric field while confined to a constant circular orbit by a magnetic field. The magnetic field serves to bend or deflect the path of the charged particles. In order to maintain a constant trajectory within the cyclic accelerator, the magnetic field must gradually increase in strength as the particle’s momentum increases. In addition the frequency of the accelerating electric field must be maintained or adjusted as necessary in order to be synchronous with the orbital frequency of the charged particles.

The Large Hadron Collider (LHC) is the world’s largest and most powerful particle accelerator. It first started up on 10 September 2008 and consists of a 27-kilometre ring of superconducting magnets with a number of accelerating structures to boost the energy of the particles along the way. Inside the accelerator, two high-energy particle beams travel at close to the speed of light before they are made to collide.Thousands of magnets of different varieties and sizes are used to direct the beams around the accelerator.

Worldwide, hundreds of industrial processesuse particle accelerators – from the manufacturing of computer chips to the cross-linking of plastic for shrink wrap and beyond. Electron-beam applications center on the modification of material properties, such as the alteration of plastics, for surface treatment, and for pathogen destruction in medical sterilization and food irradiation. Ionbeam accelerators, which accelerate heavier particles, find extensive use in the semiconductor industry in chip manufacturing and in hardening the surfaces of materials such as those used in artificial joints.

The science which underpins how radiation therapy works is based on the interaction between the nature of the particle with tumors and normal cells. External beam radiations (X rays) are delivered by linacs in order to target a large area of the body, including the tumor and surrounding normal tissues. As a result they have a lot of side effects on rapidly growing tissues such as skin and bone morrow. Electron beams are useful for targeting shallow tumors in the eye and on skin. Proton beams cause little damage to normal tissues and after deep penetration release of their energy, their use is still limited to certain types of cancer. Carbon ion radiation is active against the radio resistant tumors but their effect on normal tissues is a limiting factor and thus more research is necessary.