Today, its computer screens are dark, the control desks unstaffed and the giant, supercooled tunnel empty of the crashing proton beams whose snapshots of the Big Bang helped flush out the elusive particle.
But the silence is an illusion.
Behind the scenes, work is pushing ahead to give the vast machine a mighty upgrade, enabling it to advance the frontiers of knowledge even farther.
The 27-kilometre circular lab, straddling the French-Swiss border 100 metres underground, went offline in February for an 18-month overhaul.
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As engineers focus on the technical mission, physicists are sifting through the mountains of data that the Large Hadron Collider (LHC) has churned out since 2010, for there could be more nuggets to find.
"The things that are easy to spot have already been exploited, and now we're taking another look," said Tiziano Camporesi of CERN, noting wryly that dealing with the unknown was, well, unknowable.
The LHC's particle collisions transform energy into mass, the goal being to find fundamental particles in the sub-atomic debris that help us to understand the Universe.
At peak capacity, the "old" LHC managed a mind-boggling 550 million collisions per second.
"We give the guys as many collisions as we can," said Mike Lamont, head of its operating team. "That's our bread and butter."
"Most of that stuff is not very interesting, so there are real challenges sorting out and throwing most of that away, and picking out the interesting stuff," he explained in the tunnel, which mixes installations fit for a starship with the low-tech practicality of bicycles for inspection tours.