Scientists complete particle circulation.

The Large Hadron Collider (LHC) is back online after successfully completing its first test since the £6bn project was suspended for vital repairs around 14 months ago.

The European Organisation for Nuclear Research (Cern), which runs the collider, said in a statement yesterday that a “clockwise circulating beam” was established at 10pm on Friday evening.

“It’s great to see beam circulating in the LHC again,” said Cern 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 27 kilometre particle collider was designed by scientists at the organisation to investigate the origins of the universe by colliding photons together at the speed of light.

However the project has been beset with problems. Just nine days after circulating its first beams on 10 September 2008, the collider suffered a serious malfunction – leading to widespread damage that has taken over a year to repair.

Now that the LHC is back up and running, the next big milestone will be “low-energy collisions”, according to Cern, which are expected in about a week’s time. These collisions will give the scientists their first collision data, enabling important calibration work to be carried out.

“The LHC is a far better understood machine than it was a year ago,” said Cern’s director for accelerators, Steve Myers. “We’ve learned from our experience, and engineered the technology that allows us to move on. That’s how progress is made.”