Large Hadron Collider

History

Construction began in 1998 at CERN. The first launch was on September 10, 2008, but a few days later a serious accident disabled a sector, and repairs took more than a year. Full high-energy collisions began in 2010, and in 2012 the ATLAS and CMS collaborations announced the discovery of the Higgs boson — a particle predicted 48 years earlier.

How it works

Protons, like two trains rushing along opposite tracks, are accelerated by electric fields and held by magnets. When they collide head-on, new particles are born, like fragments from a crash. Detectors work like giant microscopes, examining these fragments.

History

Construction began in 1998 at CERN. The first launch was on September 10, 2008, but a few days later a serious accident disabled a sector, and repairs took more than a year. Full high-energy collisions began in 2010, and in 2012 the ATLAS and CMS collaborations announced the discovery of the Higgs boson — a particle predicted 48 years earlier.

How it works

Protons, like two trains rushing along opposite tracks, are accelerated by electric fields and held by magnets. When they collide head-on, new particles are born, like fragments from a crash. Detectors work like giant microscopes, examining these fragments.

History

The LHC project emerged in the early 1980s as a successor to the Large Electron-Positron Collider (LEP). After approval in 1994, construction proceeded from 1998 to 2008. On September 10, 2008, a beam was successfully circulated, but 9 days later an electrical fault caused a helium explosion and took a sector out of commission. A restart after repairs and upgrades occurred in November 2009, and the first 7 TeV collisions took place in March 2010. Thousands of CERN engineers and scientists played a key role in creating the accelerator, and the ATLAS and CMS collaborations were instrumental in discovering the Higgs boson.

How it works

Protons are accelerated by high-frequency resonators (400 MHz), and the trajectory is maintained by superconducting magnets. When counter-rotating bunches collide at the intersection points, thousands of particles are born, which are registered by multi-layered detectors: tracking systems (silicon pixels), calorimeters (electromagnetic made of PbWO₄ crystals, hadronic — iron/scintillator), muon chambers. Magnetic fields in the detectors (solenoids or toroidal magnets) enable momentum measurement. A huge challenge is extracting rare events from the background at high luminosity — this is accomplished using online trigger systems and offline analysis on computer farms worldwide (GRID).

Open problems & fun facts

The hierarchy problem: why is the mass of the Higgs boson many orders of magnitude smaller than the Planck mass, although quantum corrections should make it huge?; Dark matter: despite extensive searches, the LHC has not found candidates (WIMP particles, superpartners), challenging theories.; Incompleteness of the Standard Model: it does not include gravity, does not explain dark energy, and does not account for the observed predominance of matter over antimatter.

💡 The total energy of the beam in the LHC can melt a ton of copper. To direct a focused beam onto a graphite block, special ultra-strong absorbers — collimators — are required.