CERN's Large Hadron Collider Enters Four-Year Long Shutdown for Major High-Luminosity Upgrade

The Large Hadron Collider (LHC) at CERN has begun its third long shutdown (LS3), a four-year period dedicated to extensive maintenance, consolidation, and upgrades to transform it into the High-Luminosity LHC (HiLumi LHC). This upgrade aims to increase the collider's luminosity by a factor of ten, enabling scientists to collect significantly more data and explore rare particle processes, such as the production of Higgs bosons. The project involves replacing approximately 0.75 miles of magnets and other components, with thousands of specialists involved in this complex engineering undertaking. The LHC experiments concluded their last physics collisions on June 14, 2026, with final beam dumping on June 27, and safety operations for tunnel access began on June 29.