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    How particle colliders work

    A particle collider uses electric fields to accelerate beams of particles, magnets to steer and focus them, and detectors to record what emerges when the beams collide.[1][2] The largest, CERN's 27 km Large Hadron Collider, reaches 13.6 TeV and is being upgraded to deliver ten times more collisions from 2030.[3][4][5]

    Editor reviewedUpdated Particle physics and cosmologyPhysicsScience

    The basic recipe

    A collider is a racetrack for particles. Electric fields give the particles a push each time they go around, and magnets bend their path so they stay on the track. Everything happens inside a pipe emptied of air, so the particles do not hit gas molecules.[1] When two beams finally smash together, giant detectors around the crash point record the particles that fly out.[2]

    Acceleration happens in radiofrequency (RF) cavities. Each passage through the cavity’s oscillating field transfers energy to the bunched beam. Dipole magnets bend the trajectory, quadrupoles focus it like lenses, and the beam travels in ultrahigh vacuum.[1] Collisions are either fixed-target or beam-on-beam.[2] The LHC uses the second, with two counter-rotating beams brought together at four points.[6]

    Energy and luminosity

    Two numbers describe a collider. Energy decides which particles it can produce. The large-hadron-collider collides protons at 13.6 TeV, the highest energy reached in a laboratory.[4] Luminosity measures how many collisions it delivers, which matters for rare processes. Since its first collisions the LHC has delivered nearly 550 inverse femtobarns, almost twice its original target.[7]

    Rare processes need luminosity. CERN expects the High-Luminosity LHC to produce at least 15 million Higgs bosons a year, compared with about three million from the LHC in 2017.[8]

    Superconducting magnets

    The size of a circular collider and the strength of its magnets set its energy. The LHC’s ring is 27 km around and uses about 9,000 superconducting magnets cooled to 1.9 kelvin.[3][9] The High-Luminosity upgrade adds niobium-tin focusing magnets with fields 50% higher than today’s. It also adds “crab cavities”, which kick the particle bunches so they overlap better as they collide.[10] Work to remove the old focusing magnets beside ATLAS and CMS began in September 2026. Their replacements will reach 11.3 tesla.[11]

    Detectors

    The LHC’s beams cross at four points, where the detectors ATLAS, CMS, ALICE and LHCb sit.[12] Detectors cannot see every particle. Dark matter, for instance, would escape unseen and could only be inferred from missing energy and momentum.[13] The ATLAS and CMS detectors are getting major “Phase II” upgrades for the high-luminosity era. Delays to those upgrades pushed back the shutdown schedule in 2024.[14]

    Circular or linear, protons or electrons

    The LHC smashes protons, which belong to a family of particles called hadrons.[6] Electrons are elementary particles: they are among the six leptons of the Standard Model.[15] CERN says colliding electrons with their antiparticles would give results in unprecedented detail.[16] That is why CERN’s proposed future-circular-collider would first collide electrons and positrons as a “Higgs factory”. Later it would collide protons at around 100 TeV in the same 90.7 km tunnel.[17][18]

    The FCC plan has two stages: an electron-positron precision stage (FCC-ee), then a hadron collider (FCC-hh) at around 100 TeV in the same tunnel.[17] Other concepts compete with it. Linear colliders and colliders reusing the LHC tunnel were described by Physics Today as inferior alternatives.[19] Critics such as Michael Riordan argue for cheaper fallbacks, including an LEP3 electron-positron ring in the existing LHC tunnel, limited to 240 GeV.[20] The US P5 panel backed hosting a muon collider at Fermilab.[21]

    Questions readers ask

    How does a collider speed particles up?

    Radiofrequency cavities, metal chambers with oscillating electric fields, give the particles a push each time they pass. Magnets bend and focus the beam around the ring.[1]

    Why are collider magnets so cold?

    The LHC's roughly 9,000 magnets are superconducting and must be cooled to 1.9 kelvin (-271 °C) to work.[9]

    What is luminosity?

    In collider physics, luminosity measures how many collisions a machine delivers. The LHC delivered nearly 550 inverse femtobarns in total, almost twice its original target, and the High-Luminosity LHC is designed for ten times the original design value.[7][5]

    Sources

    Each numbered claim is a statement we checked against the sources listed with it. Status shows how well established it is.

    1. [1]

      Particle accelerators use electric fields in radiofrequency cavities to accelerate particles, dipole magnets to bend the beam and quadrupole magnets to focus it, inside a beam pipe held at ultrahigh vacuum. confirmedas of 2026-10-10

    2. [2]

      Accelerators collide particles either with a fixed target or with another beam, and particle detectors placed around the collision point record the particles that emerge. confirmedas of 2026-10-10

    3. [3]

      The Large Hadron Collider is a 27-kilometre ring about 100 metres underground on the Franco-Swiss border near Geneva; it first started up on 10 September 2008. confirmedas of 2026-10-10

    4. [4]

      The LHC collides protons at 13.6 TeV, the highest energy reached in a laboratory. confirmedas of 2026-10-10

    5. [5]

      The High-Luminosity LHC is designed to increase the LHC's integrated luminosity by a factor of ten beyond its original design value. confirmedas of 2026-10-10

    6. [6]

      The LHC accelerates protons or heavy ions, which belong to the family of particles called hadrons, in two beams travelling in opposite directions that collide at four points. confirmedas of 2026-10-10

    7. [7]

      Since its first collisions the LHC has delivered nearly 550 inverse femtobarns of integrated luminosity, almost twice its original target of 300. confirmedas of 2026-07-23

    8. [8]

      CERN expects the High-Luminosity LHC to produce at least 15 million Higgs bosons a year, compared with about three million from the LHC in 2017. confirmedas of 2026-10-10

    9. [9]

      The LHC uses about 9,000 superconducting magnets cooled to 1.9 kelvin (-271 °C). confirmedas of 2026-10-10

    10. [10]

      The HL-LHC upgrade installs niobium-tin quadrupole magnets with fields 50% higher than today's LHC magnets, sixteen crab cavities next to ATLAS and CMS, and magnesium-diboride superconducting links carrying more than 100,000 amperes. confirmedas of 2026-10-10

    11. [11]

      In September 2026 CERN began disconnecting the LHC's inner-triplet focusing magnets on either side of ATLAS and CMS; their niobium-tin replacements produce 11.3-tesla fields, about 40% stronger, the first new quadrupole is due in the tunnel at the start of 2029, and 16 cryostats and 28 cryo-assemblies will be installed in total. confirmedas of 2026-09-17

    12. [12]

      The LHC's beams collide at four points, where the four main detectors ATLAS, CMS, ALICE and LHCb are located. confirmedas of 2026-10-10

    13. [13]

      Dark matter particles produced at the LHC would escape the detectors unseen, but physicists could infer them from energy and momentum missing after a collision. confirmedas of 2026-10-10

    14. [14]

      In October 2024 CERN moved the start of Long Shutdown 3 to July 2026 and the start of High-Luminosity LHC operation to June 2030, mainly because of difficulties with the ATLAS and CMS Phase II detector upgrades. confirmedas of 2024-10-04

    15. [15]

      The Standard Model's matter particles are six quarks and six leptons, each arranged in three generations; the leptons are the electron, muon, tau and their three neutrinos. confirmedas of 2026-10-10

    16. [16]

      CERN says the FCC would collide electrons with their antiparticles, delivering collision results with unprecedented detail, and would measure the Higgs boson and other key particles with unmatched precision. confirmedas of 2026-10-10

    17. [17]

      The FCC plan has two stages, an electron-positron collider (FCC-ee) working as a Higgs factory first, followed by a proton-proton collider (FCC-hh) at a collision energy of around 100 TeV. confirmedas of 2025-03-31

    18. [18]

      The proposed Future Circular Collider would have a 90.7 km ring at an average depth of 200 metres under France and Switzerland. confirmedas of 2026-10-10

    19. [19]

      Physics Today's report described the alternatives to the FCC, linear colliders and circular colliders reusing the LHC tunnel, as inferior. reportedas of 2026-06-18

    20. [20]

      In a January 2026 Physics World opinion piece, physicist and historian Michael Riordan argued that geopolitics make it unrealistic to expect non-member countries to fund a third of the FCC, put FCC-ee's cost at about $18 billion with operations around 2050, and urged CERN to prepare a cheaper "Plan B" such as linear colliders (roughly €10 billion) or an LEP3 collider in the LHC tunnel (under €5 billion, up to 240 GeV). confirmedas of 2026-01-29· interpretation

    21. [21]

      The December 2023 US P5 report recommended early implementation of DUNE, a significant US in-kind contribution to an offshore Higgs factory, and supported hosting a muon collider at Fermilab. confirmedas of 2023-12-08

    Revision history (2)
    1. Page created.
    2. Replaced two loosely sourced general-knowledge sentences (protons vs electrons; fixed-target vs colliding beams) with directly supported statements; added the HL-LHC magnet work and the Plan B critique.

    Created Oct 10, 2026. Last reviewed by an editor on Oct 10, 2026. Next scheduled review: Jan 10, 2027.

    Cite this page

    "How particle colliders work." ContentLora, updated Oct 10, 2026. https://contentlora.com/explain/how-particle-colliders-work

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