Geneva, 6 February 2009. At the conclusion of a workshop held in Chamonix this week, recommendations have been made to the CERN1 management for the restart schedule of the Large Hadron Collider (LHC). If accepted in a management meeting on Monday, these recommendations will ensure that the LHC starts to produce physics data in late 2009, running through the winter and on to autumn 2010 at an energy of 5 TeV per beam and ensuring sufficient data for the experiments to produce their first new physics results.
“These recommendations represent the best way forward for the LHC and for the field of particle physics in general,” said Steve Myers, CERN’s Director for Accelerators and Chair of the Chamonix workshop.
Among the topics discussed in Chamonix was the underlying cause of the incident that brought the LHC to a standstill on 19 September last year. The incident was traced to a faulty electrical connection between segments of the LHC’s superconducting cable. Since the incident, enormous progress has been made in developing techniques to detect any small anomaly. These will be used in order to get a complete picture of the resistance in the splices of all magnets installed in the machine. This will allow improved early warning of any additional suspicious splices during operation. The early warning systems will be in place and fully tested before restarting the LHC.
Following the incident, a further two suspect connections have been identified. One of these has now been investigated, revealing that the splice between cables had not been correctly carried out. As a result the magnet containing the second will also be removed from the tunnel for repair. Since resistance tests can only be conducted in cold magnets, three of the LHC’s eight sectors remain to be tested: sector 3-4 where the original incident occurred and the sectors on either side. Within sector 3-4, the 53 magnets that are being replaced in the tunnel will all be tested before cool down, and the sectors either side will be cooled down early enough to intervene if necessary with no impact on the schedule. This leaves around 100 dipole magnets that cannot be tested until September, and a correspondingly small chance that repairs may run into currently scheduled running time.
“CERN’s priority for 2009 is to get collision data for the experiments, but with caution as the guiding principle,” said Myers. “The recommendations made to the CERN management are cautious, while achieving the goal of running this year.”
“A lot of hard work went into the Chamonix workshop,” said CERN Director General Rolf Heuer, “giving my management team all we need to make the right decision on LHC restart when we next meet on Monday.”
The restart schedule for the LHC will be announced following the CERN Directorate meeting on Monday 9 February.