A particle collider is a machine that accelerates particles to high energies and then smashes them together. The resulting collisions can create new particles, or reveal hidden aspects of known ones. Particle colliders are used to study the smallestknown constituents of matter – the fundamental particles.
The most powerful particle colliders are the Large Hadron Collider (LHC) at CERN in Switzerland, and the Tevatron at Fermilab in Illinois, USA. Other notable examples include the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory in New York, USA, and the Large Electron-Positron Collider (LEP) at CERN.
Particle colliders work by accelerating charged particles to very high energies using electromagnetism. The particles are then made to collide with each other or with a stationary target. The collisions release energy that can create new particles according to Einstein’s famous equation E=mc2 . This process is called pair production .
In order for collisions to take place, the charged particles must be confined within a well-defined beam pipe . To do this, particle beams are passed through a series of magnets which manipulate their path so that they remain focused on a collision course.
When two beams travelling in opposite directions intersect at the point of collision, it is vital that they do so at exactly the right angle and energy otherwise no interaction will take place between them. To ensure this happens, incredibly precise measurements are made of both beams before they reach the intersection point and corrections applied if necessary using feedback systems located upstream of the collision region . Even with all these measures in place however, beam losses still occur and specialised equipment is required to deal with this problem such as beam dumps and abort gaps .
Once two beams have collided, thousands or even millions of different interactions may take place between different combinations of particles within them. Each individual interaction produces its own unique signature which appears as an excess of events above background levels when plotted on a graph known as an event display . It is from studying these signatures that physicists gain insight into what has happened during a particular collision.