The Large Hadron Collider near Geneva will be shut off until spring 2009 while engineers probe a magnet failure.
The incident on 19 September caused a tonne of liquid helium to leak out into the experiment's 27km-long tunnel.
Officials said the time required to fully investigate the problem precluded a re-start before the lab's winter maintenance period.
The collider is built to smash Cosmic colossus ...
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Serb forces arrest Karadzic ... protons together at huge speeds, recreating conditions moments after the Big Bang.
Scientists hope it will shed light on fundamental questions in physics.
"Coming immediately after the very successful start of LHC operation on 10 September, this is undoubtedly a psychological blow," said Robert Aymar, director-general of the European Organization for Nuclear Research (Cern), in a statement.
But he praised the skill and preparation of the teams involved in building the particle accelerator.
A spokesman for Cern told BBC News it was unclear at this stage when the collider could re-start operations after the regular winter shut-down - which is carried out in part to save money on electricity.
A number of factors could affect when the lab re-opened, including a peak in electricity demand due to prolonged cold weather.
"It's usually around late March or early April that we start re-commissioning the whole accelerator chain. The LHC being at the end of that chain," said James Gillies, Cern's director of communications.
"It will take us a while to get beams injected into the LHC, but I think it's fair to say this will be the priority for next year's start-up."
The problem occurred last weekend, when 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 called out after a tonne of liquid helium leaked into the tunnel, which straddles the French-Swiss border.
The machine has more than 1,200 "dipole" magnets arranged end-to-end in an underground tunnel that runs in a circle for 27km.
These magnets carry and steer beams of protons which will whizz around the machine at close to the speed of light.
At allotted points around the tunnel, the beams will cross paths, smashing together near four massive "detectors" that monitor the collisions for interesting events.
Cern said the most likely cause of the equipment failure was a faulty electrical connection between two of the accelerator's magnets.
This connection melted during testing of the machine and caused a huge leak of super-cool helium.
This helium is used to chill the magnets to a temperature of 1.9 kelvin (-271C; -456F) - which is colder than deep space. This allows them to generate large magnetic fields required to steer the beams while at the same time consuming relatively little power.
One of the LHC's eight sectors will now have to be warmed up so that engineers can get in to inspect the faulty connection for themselves.
(BBC)
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