Large Hadron Collider
The Large Hadron Collider (LHC) is the world's largest and most powerful particle accelerator, comprising a 27-kilometre ring of superconducting magnets that accelerate protons or heavy ions to nearly the speed of light for collision at centre-of-mass energies up to 13.6 TeV in its current configuration.[1] Constructed by the European Organization for Nuclear Research (CERN) in a tunnel straddling the France-Switzerland border near Geneva, it first produced collisions in 2009 following its initial startup in 2008, enabling four major experiments—ATLAS, CMS, ALICE, and LHCb—to probe the fundamental constituents of matter and the forces governing them.[1] The LHC's paramount achievement came in 2012 with the ATLAS and CMS collaborations' observation of the Higgs boson, validating the mechanism by which particles acquire mass within the Standard Model of particle physics and culminating in the 2013 Nobel Prize in Physics for François Englert and Peter Higgs.[2] Over subsequent runs, it has identified over 50 new hadron particles, refined electroweak parameters, and searched for physics beyond the Standard Model, such as supersymmetry and dark matter candidates, while heavy-ion collisions recreate conditions akin to the early universe. As of 2025, the LHC operates in Run 3, delivering ambitious luminosity targets for proton collisions and preparing for the High-Luminosity upgrade to multiply data rates by the early 2030s. Prior to operation, the LHC faced public apprehension over hypothetical risks including micro black holes or strangelets potentially destabilizing Earth, prompting lawsuits and safety reviews; however, CERN's assessments and the Large Hadron Collider Safety Group affirmed negligible danger, noting that cosmic rays generate collisions orders of magnitude more energetic without incident.[3] Engineering hurdles, such as superconducting magnet quenches during commissioning, delayed full performance but were resolved through iterative refinements, underscoring the collider's role as a pinnacle of precision technology despite its immense stored energy exceeding 10 gigajoules in beam and magnets.[4][5]Overview
Design and Technical Specifications
The Large Hadron Collider (LHC) is a circular synchrotron accelerator utilizing the 27-kilometre circumference tunnel previously occupied by the Large Electron–Positron Collider (LEP), situated approximately 100 metres underground along the France–Switzerland border near Geneva, with maximum depths reaching 175 metres.[1][6] The tunnel's precise length measures 26.659 kilometres, comprising eight arcs each 2.45 kilometres long and eight straight sections each 545 metres in length.[6] The LHC accelerates two counter-rotating beams of protons or heavy ions within separate ultrahigh-vacuum beam pipes, employing a total of 9,593 superconducting magnets cooled to 1.9 K (-271.3°C) using liquid helium.[1][6] The primary bending is achieved by 1,232 dipole magnets, each 15 metres long and generating a nominal magnetic field of 8.33 tesla via niobium-titanium coils to maintain the beams' circular trajectory at design energies.[1][7] Beam focusing is provided by 392 quadrupole magnets, each 5–7 metres long.[1][6] Designed for a centre-of-mass collision energy of 14 TeV, corresponding to 7 TeV per proton beam, the LHC uses radiofrequency cavities—eight per beam—to boost particle energies incrementally along the ring, with beams circulating at 11,245 turns per second.[8][6] Each beam comprises 2,808 bunches containing up to 1.2 × 10¹¹ protons at injection, enabling high-luminosity collisions in the straight sections housing detectors such as ATLAS and CMS.[6]| Parameter | Value |
|---|---|
| Circumference | 26.659 km |
| Dipole magnets | 1,232 (15 m each, 8.33 T) |
| Quadrupole magnets | 392 (5–7 m each) |
| Total magnets | 9,593 |
| Design beam energy (protons) | 7 TeV |
| Bunches per beam | 2,808 |
| Protons per bunch | 1.2 × 10¹¹ |
| RF cavities per beam | 8 |