Two-month delay for the LHC


(If you read this, you are hereby obligated to read the next-to-next post.)

Bad news: a connection between two magnets in the LHC will need to be repaired due to an electrical fault, and this repair requires at least two months of down-time, because the sector will warm to room temperature in the process.  (It takes months to cool the LHC to its 2 Kelvin operating temperature.)

Here’s what happened: as a dry-run for storing a 5 TeV beam (there was no beam in the machine at the time), the dipole magnets which would hold it in its trajectory had to reach a field strength of 6 Tesla.  This is an extremely high field, about twice what someone would get in an MRI, requiring huge electrical currents.  For some unknown reason (the subject of an ongoing investigation), a connector somewhere shorted, breaking a coolant duct which then sprayed a metric tonne of liquid helium everywhere.  When the proverbial smoke cleared around mid-day yesterday, the sector was 80 degrees Kelvin.

The delay will take a rather large bite out of the 10 TeV collisions run planned for this year, but it won’t necessarily push back the start of 14 TeV collisions in 2009, since the commissioning of the magnets for full field (8.3 Tesla) is something that has to be done while the beam is not running.

Meanwhile, we have collected about 14 minutes of single-beam data since the grand opening ten days ago (that’s impressive for the early-early phase of an accelerator).  Strangely, the delay of the LHC seems somehow distant, since there are so many detector studies we need to do with these millions of events, and the presentation deadlines are so soon…


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