Crippled LHC to run at half power

Large Hadron Collider build problems worse than originally thought

The LHC will still be the most powerful proton-smasher on the planet

The Large Hadron Collider (LHC) will be restarting this winter, but only operating at half power until building problems are sorted out.

The LHC, the biggest scientific instrument in the world, had barely started functioning last summer before a major fault shut it down. Large-scale repair work began immediately but the damage is so severe that the LHC will only be able to operate at half power at first.

The LHC was designed to operate at seven teraelectronvolts (TeV) but will be limited to half that until problems with the magnetic units designed to direct the proton stream are resolved.

Rolf Heuer, director general of CERN, said: "We've selected 3.5 TeV to start 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 news will be a major blow to scientists who had hoped to use the device to solve some of the fundamental questions over how the universe is constructed. However, it will be a relief to those who worry the device could destroy the planet.

Despite the low power operation, the LHC will still be the most powerful proton-smasher on the planet. Scientists hope it will prove or disprove the existence of the Higgs boson particle, which it is postulated gives matter mass.

"The LHC is a much better understood machine than it was a year ago," said Heuer. "We can look forward with confidence and excitement to a good run through the winter and into next year."