Summary notes of the LCU meeting on 03/05/2011

Present: HB, RC, RdM, OD, MF, MG, BH, JJ,YL, MS, GV, LD

Report from meetings

• SLM and general information -> MG
  Today the EuroNNAc workshop started in which some of us are involved.
  Laurent Deniau was welcomed as new staff member in this section to take over the work as MAD-X custodian from Frank Schmidt and on the scripts for the tracking environment.
  MG reported on the progress in thick lens tracking which works for normal quadrupoles but not for skew quadrupoles, which still require slicing.
  The doctoral student requests were processed and the selection went rather well for our group. Fellow requests will be finalized this week.
  You are encouraged to look at the planning of the Optics Measurements, Corrections & Modeling Workshop  in June and to consider to register.
  The first session of LHC MDs will start tomorrow. The up-to-date schedule can be found in the MD-calendar. Several of us are involved for example in the 90m and ATS optics MDs, or the collision tune for injection, and beam-beam MDs.
  There has been a HL-LHC kick off meeting. The European request was approved with the highest mark (15/15) and negligible budget cut. Altought the CERN activities are already on-going, the European ones will be organised and launched in the coming weeks.
• LHC -> BH
  The LHC ran very well achieving new frontiers. The number of bunches was increased to 768 per beam and peak luminosities get close to 1.e33cm-2s-1. Losses were minimized with improved chromaticity, octupole, and feedback control as well as  RF re-adjusts. UFOs, vacuum spikes and SEU remain as a concern. See the latest-news for further information. 
• LBS -> HB
  The last LBS meeting discussed vacuum and backgrounds with electron clouds and scrubbing, LHC-fill analysis and news from the HL-LHC kick off meeting.

Re-matched tune compensation for 90 m beta* optics   -> HB  (slides)
HB presented last news from a dry run in preparation of the planned MD for the un-squeeze to 90m and studies to correct the beta-beating induced by the global tune correction at 90m using the main quadrupoles. The matching studies were done in collaboration with Thys Risselada.
The dry run of the un-squeeze revealed that Q4.R5B.b1 could not ramp down as fast as demanded which has been corrected for the MD. This could be due to wrong parameters of the circuits.

Concerning the tune correction for 90m, it appears to be possible to do this more locally using the main quadrupoles of the adjacent sectors and to correct the induced beta beating using a subset of the quadrupoles in these sectors, such that most of the rest of the machine is not affected. Even if this could be applied at each step of the un-squeeze, HB proposes to use is only at the last step. This proposal will not be tested during the forthcoming MD session.

AOB

None

Last update: 04-May-2011

MG & HB

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