Europe's Large Hadron Collider has begun a two-year "Long Shutdown," during which its underground components will be upgraded to run at even higher energies.
After a spectacular first act, the Large Hadron Collider is taking an intermission break, having shut down on Feb. 11 for two years of construction and upgrades.
In 2023, the ALICE experiment was ready for their best year yet, until a mysterious signal threatened everything. As the LHC wraps up its 2025 lead-ion run, physicists recall how they worked together to solve the puzzle.