when did cern shut down

CERN’s Large Hadron Collider shut down on June 29, 2026, for a planned upgrade period called Long Shutdown 3. It is expected to restart in 2030 as the High- Luminosity LHC.

What happened

The shutdown was not an emergency closure; it was a scheduled pause for maintenance, consolidation, and major upgrades. CERN says the work will prepare the machine for much higher collision rates in its next phase.

Timeline

• Last physics run ended: June 28, 2026.

• Shutdown began: June 29, 2026.

• Planned return to operation: 2030.

Why it shut down

The goal is to transform the current collider into the High-Luminosity LHC, which should produce about 10 times more collisions than before and improve the search for rare physics signals, including clues about dark matter.

Common confusion

People often say “CERN shut down,” but what actually shut down is the Large Hadron Collider, not the entire CERN organization. CERN itself continues operating while the accelerator complex is upgraded.

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