The new and much publicised giant particle accelerator near Geneva has suffered another problem and will be out of action for at least two months.
The European Organization for Nuclear Research (Cern) announced the news just 24 hours after saying its Large Hadron Collider was back in business after repairs to a transformer.
Cern spokesman James Gillies said a sector of the 27-km tunnel containing the LHC would now have to be warmed up well above absolute zero degrees Celsius so that repairs could be made.
He added that super-cooled helium had escaped probably because of a faulty electrical connection between two magnets in the accelerator.
The purpose of the huge machine is to recreate the conditions one trillionth of a second after the Big Bang more than 13 billion years ago and thus help scientists understand the formation of the universe.
The world's most expensive and complex science experiment took nearly 20 years to complete and cost SFr6 billion ($5.46 billion). Located underground outside the city of Geneva, it spans the border between Switzerland and France.
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