The £3.6bn Large Hadron Collider will be out of action for around two months after magnets over-heated, a spokesman for the project said today.
The European Organisation for Nuclear Research (Cern) said damage to the huge project below Switzerland, discovered yesterday, was worse than it first thought.
The collider, which was designed to send particles around a 16 mile circuit in a bid to unravel some of the secrets of the universe, was shut down to allow an investigation to take place.
Spokesman James Gillies said early indications were that there was a fault in an 'electrical inter-connection' between two magnets.
Scientists work on part of the Large Hadron Collider which some feared would threaten the end of the world. The machine is now out of order for two months
The fault led to a leak of helium into the tunnel and the team's in-house fire brigade turned out.
'That was standard procedure,' Mr Gillies said.
He played down the fault, which happened nine days after the machine was started.
'These kind of teething problems happen with particle colliders,' he said.
'It will take a couple of months to fix it because we operate at a very low temperature and we will have to warm the magnets up to room temperature, fix the fault, then cool them back down again.
The huge magnets of the world's most powerful particle accelerator over heated to put it out of action for two months
'The warm-up and cool-down will each take a couple of weeks.'
The cost of the damage caused was not yet known.
'An investigation is underway and as soon as we have the full details, we will release them," added Mr Gillies.
The collider requires temperatures just above absolute zero to allow particles to be steered around the circuit.
But as a result of the fault, the temperature of the magnets rose by around 100C.
Before it was started up last week, some scientists expressed fears that colliding particles could cause black holes to appear, though those concerns were strongly refuted.