Glossary
Particle physics in plain language
Twenty-six terms that are enough to read CERN news without reaching for an encyclopedia. Short, concrete and formula-free.
- Acceleratormachine
- A machine that speeds charged particles up with electric fields and steers them with magnetic fields. From a picture tube to the LHC the principle is the same; only the scale grows.
- Antimatterparticle
- The mirror image of matter: same masses, opposite charges. On contact with matter it annihilates into energy. CERN makes and traps antihydrogen.
- ATLAS and CMSmachine
- The two largest general-purpose detectors at the LHC. Independently of each other they confirmed the Higgs boson discovery in 2012.
- Bosonparticle
- A force-carrying particle: the photon (electromagnetism), gluons (the strong force), W and Z (the weak force) and the Higgs boson.
- Higgs bosonparticle
- The quantum of the Higgs field, which gives elementary particles their mass. Hunted since the 1960s, discovered at the LHC on 4 July 2012.
- CERNconcept
- The European Organization for Nuclear Research near Geneva, founded in 1954 by 12 states. The largest particle physics laboratory in the world.
- Detectormachine
- A layered instrument that records what comes out of collisions: a particle's track, energy and identity. A giant, ultra-fast camera.
- Dipolemachine
- A magnet that bends the beam's path. The LHC uses 1232 superconducting dipoles, each about 15 metres long.
- Electronvolt (eV)concept
- The energy an electron gains across 1 volt. A TeV is a trillion electronvolts; Run 3 collided protons at 13.6 TeV.
- FCCmachine
- The Future Circular Collider, a concept for the LHC's successor: a ring of roughly 91 km. Member states decide around 2028.
- Photonparticle
- The quantum of light and carrier of electromagnetism. In a detector it leaves no track in the tracker and shows up only in the calorimeter.
- Hadronparticle
- A particle made of quarks, such as a proton or a neutron. Hence the name: the Large Hadron Collider.
- HL-LHCmachine
- The High-Luminosity LHC, the upgraded machine after LS3. It should collect up to 10 times more data; start around 2030.
- Calorimetermachine
- A detector layer that absorbs a particle and measures its energy. The electromagnetic one stops electrons and photons, the hadronic one the rest.
- Cryogenicsconcept
- The technology of very low temperatures. Superfluid helium keeps the LHC magnets at 1.9 K, colder than outer space.
- Quarkparticle
- An elementary building block of hadrons. There are six kinds; a proton is two up quarks and one down quark.
- Leptonparticle
- An elementary particle that does not feel the strong force: the electron, the muon, the tau and their neutrinos.
- LS3concept
- Long Shutdown 3, the third long technical stop of the LHC, from July 2026 to around 2030. The time of the machine's biggest rebuild.
- Luminosityconcept
- A measure of how densely a machine produces collisions. The higher it is, the more data and the better the chance of rare processes.
- Muonparticle
- The electron's heavier cousin. It penetrates the whole detector, which is why muon chambers are the outermost layer.
- Neutrinoparticle
- An almost undetectable, chargeless lepton. It flies through the detector without a trace; only missing energy gives it away.
- Bunchconcept
- A packet of about a hundred billion protons travelling together. An LHC beam is thousands of bunches crossing millions of times a second.
- Protonparticle
- A positively charged hadron, the LHC's basic projectile. It comes from ordinary bottled hydrogen at the start of the accelerator chain.
- Synchrotronmachine
- A circular accelerator that raises its magnetic field in step with the growing energy, so particles stay on the same orbit.
- RF cavitymachine
- The accelerator's engine: an oscillating electric field that gives the particle bunches a push on every lap.
- Collidermachine
- An accelerator that steers two counter-rotating beams into head-on collisions. That yields far more energy than hitting a fixed target.