Summary notes of the LCU meeting on 17/04/2012

Present: HB, RdM, LD, SF, MF, MG, OH, BH, EM, MS, RT, RV

Report from meetings

• SLM and general information -> MG
  Our IPAC internal deadline is the 30 April. By that date our contributions have to be submitted to Oliver and the project leader in case they are directly related to a project. Two fellows can be selected for LCU in the upcoming committee in the context of the HL-LHC :  one to work with Stephane and one with Helmut in the context of Machine - Detector interface. Massimo said he is currently updating aperture files for the new beam-pipes to be discussed in the LEB this Friday. The LEB deals with the standard LHC and does not include the HL-LHC which requires a new strategy and more work.
• LHC Status -> BH
  The LHC is running fine. The intensity increase from 628 bunches last week to 1024 bunches now which is the last step before the nominal 1380 for the 50 ns operation. Bernard said the operation with a tilted crossing in LHCb worked without problems. One major UFO event which reached 92% of the dump level was recently observed. There has been a flash-over in a kicker magnet leading to a mis-injection with major beam losses resulting in a series of magnets quenching. It is discussed if the known critical kicker magnet will be changed in the next short stop. The difference in apparent luminosity differences between ATLAS and CMS is followed up and may require a waist optimization. Helmut added that full sets of VdM luminosity scans were successfully performed starting yesterday and completed this morning.
  See also the LHC-latest-news.
• LBS -> HB
  A first round of background observations in 2012 were discussed in the LBS#35 meeting yesterday. The background situation for CMS has clearly improved compared to 2011, showing that the vacuum intervention in the last winter stop was successful. ALICE reported that they continue to record background levels which are close the maximum they can tolerate and that the situation did not improved for them. The saw again a clear increase in the background with the increase in the number of bunches which may originate in electron cloud activities from crossing bunches in the large 800 mm chamber. A first look at local and average pressures was presented by the vacuum group. LHCb said they see some strange transition effects when the new diagonal separation is changed, but on a level which at the moment remains very safely within tolerable limits.

Last update: 20-April-2012

MG & HB

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