Large Hadron Collider back online

Cern scientists successfully complete particle circulation

The LHC has been out of action for more than a year

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

The European Organisation for Nuclear Research (Cern), which is responsible for the LHC, said in a statement yesterday that a "clockwise circulating beam" was established at 10pm on Friday evening.

"It's great to see beams circulating in the LHC again," said Cern director general Rolf Heuer. "We've still got some way to go before tests can begin, but with this milestone we're well on the way."

The 27km particle collider is designed to investigate the origins of the universe by causing protons to collide 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 LHC suffered a serious malfunction leading to widespread damage that has taken more than 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 will give scientists their first collision data, enabling important calibration work to be carried out.

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