Large Hadron Collider gears up for July restart

THE Large Hadron Collider will be back up and running by the third quarter of 2009 - probably.

According to an internal report sent to the physicists working on the giant particle-smasher at the CERN laboratory near Geneva in Switzerland, the LHC should be ready to collide proton beams at the end of July next year.

CERN's ruling council is expected to make this date official when it meets on 12 December. Yet behind the scenes, discussion about how best to go about the repairs is continuing, and one option would keep the collider out of action for all of 2009.

The accident that forced the LHC to shut down in September, less than 10 days after it started operation, highlighted weaknesses in the collider's design. The problem arose when an electrical fault punched a hole in the enclosure containing cryogenic liquid helium, causing it to vaporise. Because the gas could not escape fast enough, this led to an explosive burst of pressure that damaged neighbouring sections of the machine. Engineers plan to address this problem by improving the pressure relief system, which includes increasing the number of valves.

The decision now is whether to install this upgrade all round the LHC's 27-kilometre ring, or in stages. To upgrade the whole ring it would all have to be warmed up, effectively ruling out any chance of running the machine next year. Alternatively, the pressure relief system could be upgraded in the three sectors that are already warm, leaving any further improvements to the scheduled shutdown a year from now.

LHC project leader Lyn Evans told New Scientist that the quicker option is the only one on the table. This is borne out by Rolf Heuer, who takes over as director general of CERN on 1 January. "The priority for 2009 is to get beams in the LHC and data for the experiments," he told New Scientist. "We will be doing this as soon as possible - but no sooner."

Yet last week a presentation by Jörg Wenninger, a member of the operations team, posted on a CERN website indicated that the issue is still under consideration. "The discussion is ongoing," says Wenninger. "The people who want to be really careful would say we have to do all the upgrades and there are others that say, with all the measurements we have now, we feel extremely confident that we are taking no risks next year."

Engineers and physicists are trying to simulate the accident and will report their results in February. So while the decision to run next year seems to have already been taken - officially, at least - there is still room for a change of mind. "I doubt it will change, but you never know," says Wenninger. "At the moment the consensus is that everybody is pushing for the beam next year. But since we don't have all the information, as a cautious scientist you should be a bit careful."