Wednesday, June 24, 2015

CMS cooling magnet glitch not serious, detector will run

Two weeks ago, Adam Falkowski propagated the following Twitter rumor:
LHC rumor: serious problems with the CMS magnet. Possibly, little to none useful data from CMS this year.
Fortunately, this proposition seems to be heavily exaggerated fearmongering at this point.

On June 14th, CMS published this news:
CMS is preparing for high-luminosity run at 13 TeV
Jester's rumor was based on a true fact but all of its "important" claims were wrong.

The CMS detector has had a problem with the magnet cooling system. After some time, a problem was found in the machinery that feeds superconducting helium to the system, in particular, something was wrong with oil which reached the cold box, a component in the initial compression stage.

Repairs have shown that the CMS magnet itself has not been contaminated by oil which means that the problem was superficial and it has been hopefully fixed by now. Between June 15th and 19th, the LHC went to a "technical stop" – and the LHC schedule also says that since last Saturday to this Sunday, the LHC is scrubbing for the 50 ns operation – but once it is over, the CMS should be doing all of its work again.

Starting from next Monday, the LHC should be ramping up the intensity with the 50 ns beam for 3 weeks. July 20th-24th will be "machine development". Following 14 days will be "scrubbing for 25 ns operation". Intensity ramp-up with the 25 ns beam will begin on August 8th.

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