Late start for Large Hadron Collider

Physics Today : CERN has confirmed that repairs to the Large Hadron Collider (LHC) will be complete in early spring and that experiments will start up in the late summer, some three months later than they originally hoped (see PHYSICS TODAY November 2008, page 24 ). The LHC may also be run during 2009 at lower energies as an extra precaution. “The top priority for CERN today is to provide collision data for the experiments as soon as reasonably possible,” said outgoing CERN Director General Robert Aymar .

The LHC suffered a serious setback on the 19 September when a faulty electrical connection between two of the accelerator’s magnets caused the magnets to fail and rupture. The resulting damage in the 3 km section of the 27-km-long machine (see image. The two magnets should be perfectly aligned) also released liquid helium into the tunnel.During the winter, a total of 53 magnet units will have to be removed from the tunnel for cleaning or repair, along with 14 short straight sections of the machine that houses some of the quadrupole magnets. According to a report released earlier today , of these, 28 of these magnet units have already been brought to the surface. The first two replacement units have been installed in the tunnel.The current schedule foresees the final magnet being reinstalled by the end of March 2009, with the LHC being cooled down with liquid Helium and ready for powering tests by the end of June 2009. In the original schedule the LHC would be restarted in April. The vacuum pipes of entire section in which the damage occurred are also being checked for soot damage, caused by the electrical arcs that happened during the failure."We have a lot of work to do over the coming months,” said LHC project Leader Lyn Evans, “but we now have the roadmap, the time and the competence necessary to be ready for physics by summer. We are currently in a scheduled annual shutdown until May, so we’re hopeful that not too much time will be lost."In a seminar to CERN staff earlier this week, Aymar said he was confident that the LHC’s engineers have identified ways to prevent a similar incident from reoccurring in the future.