Cern's Large Hadron Collider has been closed down for two months after suffering a technical fault.
The machine, opened in a blaze of publicity earlier this month, was turned off at the weekend as engineers probed a technical fault.
As a result, the Large Hadron Collider near Geneva will be out of action for at least two months, said Cern.
A magnet failure in the £3.6bn particle accelerator was the cause of the problem.
Last Friday, a failure known as a "quench" caused around 100 of the LHC's super-cooled magnets to heat up by as much as 100 degrees.
The fire brigade were then called out after a tonne of liquid helium leaked into the LHC tunnel.
Cern admitted the repair work could prove costly. The machine will now have to be warmed up to make the repair, and then cooled down again to get back to the necessary operational temperature.
The LHC is being used to try to discover what happened after the time of the Big Bang.