• Follow-up of actions from previous meetings
  • Transverse displacement of IP2: beam-beam separation (WH)
    • This subject was postponed for a future meeting. BJ mentioned that the study should include IP8 as well.
  • Generation of new web pages for the optics V6.500
    • JJ is working on this.
  • News from the optics database -> TR
    • Aperture
      1. Files from SR were included and JJ produced a compressed version of the aperture model (4 files: with/without mechanical tolerances B1/B2).
      2. RA asked about the use of the aperture model. MG said that it is very important for MEB activities (magnet geometry qualification).
      3. BJ asked for some documentation and follow up of changes. RA commented that the aperture model should be considered as frozen and SR cannot further follow up due to his activities in the OP group.
    • Version 6.501
      1. TR mentioned that polarity check and debugging was done in particular in the triplet correctors.
      2. Misalignment errors work for MBs and MQs but some complexity for the magnets from Q7 to the IP.
      3. RA asked  when this version will be ready in order to make some cross-checking for the beam losses and collimation activities. TR replied that Sammy Chemli will finalise the layout soon.
      4. JJ mentioned that some new tools with Mathematica were developed in order to handle the class hierarchies through the oracle database.
• Report from meetings
  • MEB, LTC -> MG
    • Presentation and approval activity continued for SSS, dipoles, triplets and warm dipoles.
    • Hot topic is the MB allocation of sector 6-7 and conflicts between magnet production and installation schedule.
  • TCC -> BJ
    • The problems with the QRL are over.
    • No news about new database schedule.
  • Sector test meeting -> HB, MG
    • HB announced that the sector test will very unlikely not take place this year as DFBs are not available.
  • LHCCWG -> MG
    • A discussion took place on the commissioning of the collimators. RA added that an operational model is needed and some realistic scenarios depending on the beam, beta beat and orbit correction.
  • Collimation meetings -> RA
    • An issue with the RF finger tests on industry occurred, due to the absence of smooth handling. There may be an aperture reduction from 60 to 58mm. BJ will check for IR6.
    • The position for the collimation for TOTEM is 15σ and the request for 5 to 10σ is impossible to be fulfilled.
  • FQWG -> RdM (minutes are available here)
    • RdM presented some results on the emittance blow up due to the vibration of the beam screen in the LHC dipoles with frequencies of a few kHz. A preliminary study indicates that this gives a field variation of 10^-8 which may double the emittance in 10h. A request for additional measurements in an LHC dipole was made but it may not be easy due to the tight LHC schedule.
• Collimation: First Beam 2 Results and Input for Studies in the IR -> TW (pdf file)
  • The simulation for producing loss maps tracks 5 million particles over 200 turns and records loss location with a 10cm resolution.
  • Out of the 5 available optics flavors (V6.500) , simulation was done for 4 of them so far, and
  • Some special simulations were also performed with  increased gap configurations for the TCTV (impedance reduction).
  • At injection, the vertical efficiency is better than the horizontal for both beams. TR mentioned that due to a bug there was an asymmetry in the optics between the two beams in IR5 and this may explain the asymmetry  observed in the collimation efficiency simulations.
  • At collision, the collimation efficiency is equivalent in both planes.
  • Special simulations were done for the IRs for understanding quench threshold and cleaning efficiency with tertiary collimator and create loss maps as input for shower studies (MARS) for estimating background in experiments
• Advances on the MAD-X on-line model -> FS (pdf file)
  • MADX 3.03 version completed and frozen.
  • Main MADX limitation for on-line modeling is field errors assignment. This may be solved with a special version called MADXP (MADX+PTC). RA, HB and MG express their concern regarding the ability to use the on-line model for off-line tracking with SIXTRACK, if the MADXP solution is adopted, without the ability to create easily an equivalent on-line MADX input.
  • The communication with the control system will be done through tfs tables (transformation to SDDS and vice versa).
  • A fellow will be recruited to help on the task.
• First results for collimation commissioning and error scenarios -> CB
  • The talk was postponed for the next meeting due to lack of time.

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