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LHC First Run Parameters

Cosmic Variance
By JoAnne Hewett
Aug 6, 2009 6:58 PMNov 5, 2019 8:44 PM


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A question that we have all been asking has been answered today: What will be the LHC run energy? A press release has just been issued from CERN Director General, Rolf Heuer, following the completion of tests on the LHC magnets and splices. Here are the excepts which just beeped into my inbox:

The LHC will run for the first part of the 2009-2010 run at 3.5 TeV per beam, with the energy rising later in the run. That's the conclusion that we've just arrived at in a meeting involving the experiments, the machine people and the CERN management. We've selected 3.5 TeV because it allows the LHC operators to gain experience of running the machine safely while opening up a new discovery region for the experiments. The developments that have allowed us to get to this point are good progress in repairing the damage in sector 3-4 and the related consolidation work, and the conclusion of testing on the 10000 high-current electrical connections last week. With that milestone, every one of the connections has been tested and we now know exactly where we stand.

The procedure for the 2009 start-up will be to inject and capture beams in each direction, take collision data for a few shifts at the injection energy, and then commission the ramp to higher energy. The first high-energy data should be collected a few weeks after the first beam of 2009 is injected. The LHC will run at 3.5 TeV per beam until a significant data sample has been collected and the operations team has gained experience in running the machine. Thereafter, with the benefit of that experience, we'll take the energy up towards 5 TeV per beam. At the end of 2010, we'll run the LHC with lead-ions for the first time. After that, the LHC will shut down and we'll get to work on moving the machine towards 7 TeV per beam.

This is welcome news. Starting at injection energy (450 GeV/beam) for a few shifts is safe and smart. Experimenters will be guaranteed to record some data which will be used to calibrate the detectors. Detectors must be properly aligned and calibrated before we can have discoveries! Then they will ramp up and run awhile at 3.5 TeV/beam, giving the LHC its long-awaited status of being the highest energy accelerator in the world. A short run at this energy does not have much discovery room given the strong constraints on new physics from the Tevatron, but will mainly serve to further calibrate the detectors and build up experience running the machine. Finally, a slow ramp up to 5 TeV/beam seems like a safe option for the machine, and allows for the possibility of discovery by the end of 2010!

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