Connecting up the LHC

Within the LHC, the world’s largest particle collider, the protons will not race around the 27 km ring at near the speed of light of their own accord. Instead they are guided by huge superconducting magnets running through eight separate sectors. Each of these must be sealed in a vacuum and cooled to a freezing –271.3°C, just 1.9 degrees above absolute zero. In fact the whole ring consists of a wealth of electrical lines and piping forming an intricate system running the full 27 km of the LHC, which must connected before the beam can run.

On Wednesday 7 November, CERN’s Director General, Robert Aymar, symbolically tightened a special gold–plated bolt in the tunnel, the last in sector 1-2, signifying the completion of all the arc interconnections within each sector. At a party to celebrate the event, the LHC project leader Lyn Evans called it an “astonishing achievement, for me the hard part is now done”.

Indeed, this was no easy feat. On this same date last year just one sector had been completed, but now all eight are ready. All in all over 1700 magnets have been connected together, implying a total of about 40 000 leak-tight welds (1 0km worth!) and 65 000 electrical ‘splices’ of superconducting cables. High quality is essential; a leak in the cryogenic system that cools the LHC or a fault in an electrical line would mean warming up a whole sector to fix it.

This surge in production came from an organized coordination effort that involved working in parallel on up to six sectors at the same time with tight changeovers between teams. To ensure that problems in quality could be solved as quickly as possible, CERN staff even installed a call centre that was always open to deal with problems as they arose. And of course, sheer dedication got much of the work done: “There are a number of people who have dedicated the last few years to this project without much regard to their personal schedule or clock,” explains Francesco Bertinelli, interconnections project leader.

Teams will now test the recently connected sectors before cooling them down in preparation for the start-up of the complete machine in spring next year, and the golden bolt will become just one of many essential in running the LHC.

November 2007