Summary notes of the LCU meeting on 05/02/2013

Present: FB, Rb, HB, RdM, LD, OD, SF, MHF, MG, PH, BH, JJ, LL, SR, MS, RT, AV, RV, FZ

Report from meetings

• SLM and general information -> MG
  Massimo informed us that Stephane is stepping down as HL-LHC WP2 leader and that Gianluigi will take over this function.
  Some restructuring of our group can be expected for this year. We currently have a mixture of separation into sectors by machine or competence. It is proposed to restrict our section not only to the LHC machine but also include more generally single particle activities previously done in the LIS section. It is also planned to open up the CC3 section to include studies of other future lepton machines like LEP3 or TLEP.
  Several of us said they were quite happy with the present structure concentrating on the LHC, and that we should not be too restrictive on concentrating only on single particle motion.
  For collimation for example, the impedance is of similar importance as optics and single particle tracking.
  MG will inform the management of the comments received and encourages all LCU members to contact him directly for discussing the restructuring and providing additional feedback.
• LHC status, BH
  Bernard said, that the LHC recently switched from p-Pb to Pb-p, which required some re-optimisation to minimise losses in the squeeze. The LHC operation is scheduled to stop next Monday (extended by the DG after the meeting to Wednesday, with time for a reduced energy pp run).
• LMC, FZ
  Frank reported about the recent LMC#160, 161 meetings. For details see the LMC minutes.
• LBS -> HB
  Helmut reported from the recent LBS#43 meeting. Background conditions in the pPb run are good. Still, CMS and ATLAS would like to better understand high-multiplicity backgrounds, seen on a low level.
  Background simulation were presented for ALICE. Details can be found on indico.
• Collimation status -> SR
  Stefano said that the collimation team is very busy with the current proton lead run and that they will also be involved in the quench tests which will follow the operation with beam.  They plan a workshop in spring, probably May. Stefano will circulate possible dates.
• MAD-X status -> LD
  Laurent said he plans for a MAD-X pro-release next week and that he is organised discussions with experts on automated software testing.
• SixTrack status -> RdM
  Riccardo introduced Mattias Fjellstrom to our group, who works with him as technical student on SixTrack on subjects like tracking with an exact Hamiltonian. Another plan is to implement automatic testing oriented on what is currently done for MAD-X. 

Analysis of IR8 aperture measurements -> PH (slides)

Pascal Hermes presented aperture measurements and studies for IR8. Recent measurements with bumps and TCT alignment were used to verify the aperture in IP8 with beams.

The apertures measured are close to the expected 24 mm. Bernard said this is important input for the discussion of the optimal crossing angle orientation. Non-linearities in the BPM response, in particular in the vertical plane, make it difficult to predict the real beam positions in the presence of crossing angles. Small differences on the level of mm are seen between the beams and transverse planes. It is planned to further improve on the modelling of the BPM non-linearities.

Specifications of orbit correctors for new triplet of HL-LHC -> RdM (slides)

Riccardo presented studies for the specification for new HL-LHC triplet orbit correctors, done in collaboration with Stephane and Massimo. Stronger correctors are required such that the separation and crossing angle bumps can be closed before the crab cavities. More strength is required in particular in the Q3 region and also in the D2-Q4 area close to the  crab cavities. The correctors should also allow for orbit corrections to compensate for misalignments up to +/- 0.5 mm. The studies also considered injection with beat* = 6m, 11, or 18m.
Helmut asked to also check on the possibility for VdM scans which are currently done without the MCBX correctors to minimise uncertainties from hysteresis effects.

AOB

None

Last update: 08-February-2013

MG & HB

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