The European Organisation for Nuclear Research (Cern) plans to restart its Large Hadron Collider (LHC) in November at a level it says will not overtax the machinery behind the giant particle physics experiment, which has experienced a year of setbacks.
The collider, located deep underground on the border between France and Switzerland, will start running at an energy level of 3.5 trillion electron volts (TeV) per beam, about half the energy that Cern eventually expects to use.
The physicists will inject and capture high-energy beams running in each direction on the circular collider's 17-mile circumference, log data over a number of weeks, and develop familiarity with the systems.
"We've selected 3.5TeV to start," Rolf Heuer, director general of Cern, said in a statement on Thursday, "because it allows the LHC operators to gain experience of running the machine safely while opening up a new discovery region for the experiments."
The collision of subatomic particles in the LHC could offer insights into the earliest workings of the universe.
The machinery is immensely complex, with 10,000 high-current superconducting electrical connections. The collider has cost €10bn (£8.5bn) and taken 15 years to develop.
It was one of those electrical connections that misfired shortly after the collider was turned on for the first time in September 2008, causing Cern to curtail operations while it investigated and repaired the problems and planned its next steps.
Tests of the collider's copper stabiliser ended satisfactorily last week, meaning "no more repairs are necessary for safe running this year and next," Cern announced on Thursday.
"The LHC is a much better understood machine than it was a year ago," Heuer said. "We can look forward with confidence and excitement to a good run through the winter and into next year."
After a significant data sample has been collected running the LHC at 3.5TeV per beam, Cern said it would move toward 5TeV and, at the end of 2010, would introduce lead ions for the first time.
Then it will be time to shut down the collider once again to prepare the machinery to run at 7TeV. According to Cern's glossary "1TeV is about the energy of motion of a flying mosquito. What makes the LHC so extraordinary is that it squeezes energy into a space about a million million times smaller than a mosquito."
