The Large Hadron Collider (LHC), the world’s most powerful particle accelerator, comes to the end of an extraordinary chapter in its scientific journey. Following its final physics run, the accelerator has been switched off to begin CERN’s Long Shutdown 3 (LS3), a major programme of maintenance, consolidation, upgrades and installation work that will prepare the Laboratory for the High-Luminosity LHC (HiLumi LHC), the next phase in the exploration of the fundamental laws of nature.

Since circulating its first beams in September 2008, the LHC has pushed the frontiers of science and technology, becoming one of the most ambitious scientific instruments ever built. The accelerator delivered its first proton collisions in 2009 and rapidly established itself as a unique discovery machine – across three operational periods (Runs 1–3), the LHC delivered unprecedented quantities of data to its experiments.

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In the LHC caverns, the ATLAS and CMS experiments will undergo extensive upgrades, effectively becoming renewed detectors.

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While no particle beams will circulate during this period, CERN’s scientific activity will remain intense. Thousands of researchers will continue analysing the vast datasets accumulated during the LHC era, extracting new physics results while simultaneously preparing the experiments for the challenges ahead.

When the accelerator complex gradually restarts, from 2028, it will inaugurate a new era for high-energy physics. Building on the legacy of the LHC, the HiLumi LHC will provide unprecedented opportunities to deepen our understanding of the Universe and explore some of the most fundamental questions in science.