After a year of setbacks, CERN plans to restart its Large Hadron Collider in November at a tempo that won't overtax the machinery behind the giant particle physics experiment.
The collider, located deep underground on the border between France and Switzerland, will start out running at an energy level of 3.5 trillion electron volts (TeV) per beam, about half the energy that CERN expects eventually. 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 simply get themselves up to speed on the systems.
"We've selected 3.5 TeV to start," Rolf Heuer, director general of CERN, said in a statement 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 experiment that CERN--the European Organization for Nuclear Research--has in mind are nothing short of grandly ambitious. The collision of subatomic particles in the Large Hadron Collider could offer insights into the very earliest workings of the universe.
And the machinery is immensely complex, with 10,000 high-current superconducting electrical connections. The collider has cost $9 billion and taken 15 years to get to where it is now, according to an article earlier this week in The New York Times.
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 moved on to investigate and repair the the initial problems--and then subsequent troubles--and to plan its next steps. Tests of the collider's copper stabilizer wrapped up satisfactorily last week, meaning "no more repairs are necessary for safe running this year and next," CERN announced 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 3.5 TeV per beam, CERN said it would move toward 5 TeV 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 as CERN gets ready to get the machinery running at 7 TeV. ("1 TeV," says CERN's glossary, "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.")