Editing Compact Linear Collider (section)

== Background ==
There are two main types of particle colliders, which differ in the types of particles they collide: [[lepton]] colliders and [[hadron]] colliders. Each type of collider can produce different final states of particles and can study different physics phenomena. Examples of hadron colliders are the [[Intersecting Storage Rings|ISR]], the [[Super Proton Synchrotron|SPS]] and the LHC at CERN, and the [[Tevatron]] in the US. Examples of lepton colliders are the [[SuperKEKB]] in Japan, the [[Beijing Electron–Positron Collider II|BEPC II]] in China, [[DAFNE]] in Italy, the [[VEPP-2000|VEPP]] in Russia, [[SLAC National Accelerator Laboratory|SLAC]] in the US, and the [[Large Electron–Positron Collider]] at CERN. Some of these lepton colliders are still running.

Hadrons are compound objects, which lead to more complicated collision events and limit the achievable precision of physics measurements. This is for instance why the Large Hadron Collider was designed to operate at such a high energy even while it was already known the Higgs particle ought to be found at around the energies it eventually was: the lesser accuracy of a hadron collider necessitated more numerous and higher energy impacts to compensate. Lepton colliders on the other hand collide [[Elementary particle|fundamental particles]], therefore the initial state of each event is known and higher precision measurements can be achieved.

Another means of categorizing colliders is by their physical geometry: either linear or circular. Circular colliders benefit from being able to accelerate particles over and over to reach very high energies, and from being able to repeatedly intersect their beams, to reach very high numbers of collisions between individual particles.

On the other hand they are limited by the fact that keeping the particles circulating means constantly accelerating them inwards. This makes charged particles emit [[synchrotron radiation]], eventually leading to a significant energy loss and a limit on achievable collision energy. This so called synchrotron loss is especially harmful to lepton colliders, because it scales as the fourth power of particle speed, and the only stable leptons around (electrons and positrons) are, as the name says, very light. They will have to be accelerated to much higher speeds than heavier particles (baryons) in order to gain the same energy, and suddenly synchrotron loss becomes the limiting factor.

As a linear collider, CLIC will not have this problem. It still has to tackle the problems of not being able to recirculate its beams, though, which despite it being called "compact", necessitates massive scale and a rather unconventional design to reach the high linear accelerations required.