Synchrotron, << SIHNG kruh tron, >> is a device that accelerates electrons and protons to high energies. It is a type of particle accelerator that makes particles travel in circular orbits. Physicists use the synchrotron to study the structure and forces of the atomic nucleus.
Electrons or protons are released into a synchrotron after they have been sped up in another type of accelerator, usually a linear accelerator. In the synchrotron, they travel inside a doughnut-shaped vacuum chamber that lies within a ring of magnets. These magnets produce a magnetic field that keeps the particles in the chamber by bending their paths into circular orbits. Each time the particles make a complete orbit, they are accelerated by an electric field generated by devices located between two of the magnets. The electric field alternates in step with the revolutions of the particles, giving the particles a slight energy boost each revolution.
A synchrotron’s magnetic field is gradually increased in strength as the particles gain energy. This increase in field strength bends the particles into orbits of constant radius and thereby keeps them in the vacuum chamber until they can be boosted to even higher energies. When the particles reach the desired energy level, they are directed to a solid or liquid target outside the chamber, or are transferred to another machine, such as a storage ring. The particles can be held at the desired energy in a storage ring for many hours. The collisions of the particles with a target or with another particle beam in a storage ring produce mesons and other subatomic particles. Physicists study the particles that result from these collisions.
In electron synchrotrons, enormous amounts of energy are radiated away by the electrons as they travel through the magnetic field. This intense synchrotron radiation, which is continuously replaced by power sources within the accelerator, is used as a light source for various industrial and research applications.
In 1945, Vladimir I. Veksler, a Soviet physicist, and Edwin M. McMillan, an American physicist, independently announced the idea of a synchrotron. Their ideas were based on a principle called phase stability. Phase stability ensures that an accelerator’s particles remain in step with the electric field when the strength of the magnetic field is slowly increased. In the early 1950’s, physicists developed a method to improve particle-orbit stability. This method, called strong focusing, involves using special magnetic fields designed to keep the particles focused in a narrow stream. Strong focusing enabled scientists to design synchrotrons that could speed particles to many billions of electronvolts (GeV).
In 2001, a proton synchrotron at the Fermi National Accelerator Laboratory (Fermilab) in Batavia, Illinois, called the Tevatron accelerated protons to energies up to 980 GeV. In 2009, the Large Hadron Collider (LHC) built on the Swiss-French border, surpassed the Fermilab machine as the most powerful accelerator in the world. Maintained by the European Union’s CERN lab, the LHC is built to accelerate protons to up to 7 trillion electronvolts.
See also X rays (Synchrotron radiation).
