After more than 15 years of operation, the Large Hadron Collider has completed its final physics run and entered Long Shutdown 3. Since its first beams circulated in September 2008, the world's most powerful particle accelerator has delivered groundbreaking discoveries. The shutdown marks the beginning of an extensive upgrade program that will transform the facility into the High-Luminosity LHC, scheduled to begin operations in 2030.

The LHC's most significant achievement came on July 4, 2012, when ATLAS and CMS collaborations confirmed the Higgs boson discovery. Over three operational runs, the collider enabled more than 85 hadron discoveries, set exclusion limits on new particles, and advanced our understanding of matter-antimatter imbalance. Beyond scientific output, the facility drove innovations in superconducting technologies and computing infrastructure that extended far beyond particle physics.

During LS3, approximately 1.2 kilometers of magnets and components will be replaced throughout the accelerator complex. The ATLAS and CMS experiments will receive entirely new trigger systems and detector technologies, including all-silicon tracking with billions of readout channels and timing detectors with picosecond resolution. These upgrades must handle 140-200 proton-proton collisions per bunch crossing—more than triple the current rate—while processing over five billion interactions every second.

Thousands of specialists from CERN and partner institutes worldwide will work on this transformation through 2030. Scientific activity continues during the shutdown as researchers analyze accumulated datasets and prepare experiments for the unprecedented performance of the Hi Lumi era. The upgraded collider will enable precision studies of the Higgs boson and extend the search for phenomena beyond the Standard Model.