Monday, February 9, 2009

LHC Schedule, Part 1

As soon as DG Heuer (DG = Director General of CERN) got back from a workshop in Chamonix (see map) last week,

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he sent CERN users and staff an email along with a Press Release. The contents: a recommendation for running the LHC through the winter of 2009-10 all the way to autumn of 2010, at an energy of 10 TeV (compare this to the "design" energy of 14 TeV, and the proton-antiproton energy of 1.96 TeV at Fermilab's Tevatron). This should give the experiments enough data to get our physics on :)

At this workshop (which was mostly for the Accelerator division, as I understand it only a few representatives from the experiments were invited) they also discussed the cause of September 19th incident and what they've done to detect similar potential problem spots in the machine:

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.

So there's the latest dish on the machine. The "Part 1" in the title of this post refers to the caveat that the schedule recommendation needs to be approved by CERN management in a meeting today. I'll post again when we get word on the decisions that were made in that meeting, which I hope will give us a more detailed restart schedule for this year.

A bientôt!

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