Summary (tl;dr)

CERN's Large Hadron Collider (LHC) has officially shut down for a four-year upgrade period, known as Long Shutdown 3 (LS3), to transform it into the High-Luminosity LHC (HL-LHC) for future experiments.

Essential Background

The Large Hadron Collider (LHC), operated by the European Organization for Nuclear Research (CERN), is the world's most powerful particle accelerator, spanning 27 kilometers underground across the France-Switzerland border. Since its first operations in 2010, the LHC has been instrumental in groundbreaking discoveries, most notably the Higgs boson in 2012, which helped explain the origin of mass. Particle accelerators like the LHC periodically undergo planned shutdowns for maintenance and upgrades to enhance their capabilities. The LHC completed its third operational run (Run 3) recently, having increased its collision energy to 13.6 TeV.

The Full Story

On June 29, 2026, the Large Hadron Collider officially ceased operations, entering its third major upgrade phase, known as Long Shutdown 3 (LS3). This extensive shutdown is projected to last four years, with the High-Luminosity LHC (HL-LHC) scheduled to begin operations in 2030. The upgrade is a substantial engineering undertaking, involving the removal and replacement of 1.2 kilometers of accelerator components, along with significant renovations to detectors and infrastructure across CERN's accelerator complex. While no particle beams will circulate during this period, thousands of researchers will continue to analyze the vast datasets already accumulated and prepare for the next era of high-energy physics.

Why It Matters

This shutdown is a critical step towards the High-Luminosity LHC, which will increase the collision rate by up to tenfold compared to its predecessor, allowing scientists to gather significantly more data. The increased luminosity will enable more precise studies of the Higgs boson and provide unprecedented opportunities to search for new phenomena that could reveal physics beyond the Standard Model, potentially shedding light on mysteries like dark matter and the imbalance between matter and antimatter. The upgrade represents a significant leap in humanity's quest to understand the fundamental laws of the universe, pushing the boundaries of technology and scientific exploration for decades to come.

Geographic Location

• CERN (European Organization for Nuclear Research), Meyrin, Geneva Canton, Switzerland (headquarters and primary location of accelerator complex operations)
• The 27-kilometer underground tunnel beneath the France-Switzerland border near Geneva (location of the Large Hadron Collider and ongoing upgrade work)