Large Hadron Collider (LHC) Switched On again

A picture of the Large Hadron Collider taken while under construction

Scientists have switched on the world's largest atom smasher for the first time since the £6bn machine suffered a spectacular failure more than a year ago.

It has taken a year of repairs for beams of protons to once again be circulated in the Large Hadron Collider, which had been heavily damaged by a simple electrical fault.

The European Organisation for Nuclear Research has taken the restart of the collider step by step to avoid further setbacks as it moves towards new scientific experiments - probably starting in January - regarding the make-up of matter and the universe.

Progress on restarting the machine, on the border between Switzerland and France, went faster than expected and the first beam circulated in a clockwise direction around the machine at about 10pm local time, said spokesman James Gillies.

"Some of the scientists had gone home and had to be called back in," he said.

The exact start time of the Large Hadron Collider was difficult to predict because it was based on how long it took to perform steps along the way, and in the end it happened about nine hours earlier than expected, Mr Gillies said.

This is an important milestone on the road towards scientific discoveries at the LHC, which are expected in 2010, he said.

About two hours later the scientists circulated another beam in the opposite direction. The LHC also will be used later for colliding lead ions - basically the nucleus of the element that is about 160 times as heavy as a single proton. That should reveal still more scientific secrets.

"It's great to see beam circulating in the LHC again," said Director General Rolf Heuer. "We've still got some way to go before physics can begin, but with this milestone we're well on the way."

The first beams were circulated on September 10, 2008. But the machine was sidetracked nine days later when a badly soldered electrical splice overheated and set off a chain of damage to massive superconducting magnets and other parts of the collider, in a 17-mile circular tunnel under the Swiss-French border. £24.2m has been on repairs and improvements to avoid a repetition.