Presents: HB, RDM, SF, MG, WH, JBJ, DK, AK, AL, EM, TR, FR, FS, AV, FZ

• Follow-up of actions from previous meetings
  • Field errors for triplet magnets -> FS
    • Magnetic data for single magnets are still missing due to a problem with the analysis of the measured data (initial phase of the measurement mole not taken into account properly in the analysis). The situation will be reported at MEB this afternoon with the aim of calling for a meeting with responsible people in AT Dept. to define the best strategy. Once the data will be made available, a presentation at the FQWG should be foreseen.
• Report from meetings
  • LTC, SLM -> OB
    • AV reports that his presentation at the LTC on IR4 tuneability did not raised any burning question.
  • WGA -> JBJ
    • Tolerances for the external lines of SSS were officially delivered.
    • Tolerances for "golden SSS" should be ready in a week.
    • Issue of inter-axis distance at the level of MSCB is still not understood.
• Status of magnet activities workpackages  -> SF (pdf file)
  • Activities are well-advancing on all classes of magnets, i.e. dipoles and spool pieces, main quadrupoles and lattice correctors, insertion magnets, and triplet quadrupoles.
  • The really critical issue concerns the triplet, as the detailed analysis required for magnet evaluation and slot allocation is blocked due to missing magnetic data.
  • Review of the status every two, three months will be made.
• LHC IR upgrade Studies -> RDM (pdf file)
  • The configuration studied is the so-called "dipole first".
  • An optical solution was found.
  • It is suggested to have a rough estimate of the characteristics of the two-in-one quadrupoles (e.g. apertures) to have a preliminary evaluation of the feasibility of the scheme.
  • It is suggested to have a separate dipole corrector to generate the vertical crossing scheme.
  • Issues to be studied next: chromaticity correction and dynamic aperture.
• Preparation and status of beam-beam tracking  -> WH (pdf file) DK (pdf file)
  • Preparation of the beam-beam simulation campaign is over. This required:
    • Development of a new environment/scripts to perform tune scans
    • Development of the tool to submit the jobs to CPSS and BOINC
    • Modifications in MADX
  • It is suggested to improve the CPU-time requirements for tune-scans by
    • Performing short-term runs to rule out bad tunes.
    • Not performing a grid scan, but rather a sort of guided search (simplex method, simulated annealing, etc.) to find the best tune.
  • It is suggested to perform a scan over the phase advance between the insertions.
• AOB
  • Influence of field quality of cold D3, D4 separation magnets -> MG (pdf file)
    • A study of the impact of the cold D3 and D4 dipoles was performed by using:
      • Field quality in official error tables, i.e. D1-like field quality for D3 and D2-like field quality for D4.
      • Expected field quality according to BNL reports/web site.
      • In the case of D3 the difference between the two sets of error is mainly b3 (lead and return end, body, both at injection and collision).
      • In the case of D4 the difference between the sets of errors is mainly b3 (body, both at injection and collision).
    • A reduction of about 0.5-1 sigma in DA is found when the expected error tables are used.
    • The culprit for DA reduction is b3 in D4 magnets.
    • Measured field quality in D4 magnets turned out to be better than expected one. Therefore, the situation seems to be safe.
  • Crossing angles for intermediate values of beta* -> JBJ
    • Following a number of discussions between I. Bayshev and people in the LEA Group, there is a request to have a complete optics settings, i.e. including also crossing angles, for beta*=2 m.
    • Such a configuration is already available in the database, but the crossing angle scheme is missing.
    • A guideline to define the crossing angle should be given by the analysis of the beam-beam effect: it is decided that the value of the minimum crossing angle be defined by beam-beam experts (WH). Other consideration will then dictate the choice of the optimal value compatible with beam-beam.

Colour code:

• Black: proposed agenda
• Red: outcome of discussion at the meeting