• Report from meetings
  • MEB -> MG
    • Started approval of dipoles and SSS from sector 5-6.
    • SSS have been pre-allocated for all 4 of the remaining sectors .
    • Insertion quads are being studied and approved in batches (IR8 almost finished, IR1 and IR5 to follow).
    • The quench performance and field quality of MQTL is not brilliant. A crash program from ABP was initiated to check if field quality is still acceptable.
  • TCC -> JBJ (minutes are available here)
    • The fragility of the external compensators that may endanger the stability of the QRL was revealed with major impact in installation and planning.
    • The adjustment of the collimator position in Q4 and Q5 at IR3 was accepted, as well as the displacement of the TAN (D. Macina).
    • The approval for additional absorbers to IR3 and IR7 is closed waiting for the final document.
  • SLM -> MG
    • For accessing the new control room a registration procedure is initiated through EDH, and a special card has to be retrieved in bldg 55. There is a different access request for accessing the CCC and the kitchen.
    • The total requests for EPAC06 participation from the AB Dept. were 41. Taking into account the limited quota (not including invited talks and students), 28 were approved and among them, the following ABP group members:  Ralph, Oliver, Christian, John, Alex, Andrea, Yannis, Giovanni and Rogelio.
  • Collimation project meeting -> RA
    • The collimators are on the critical path with respect to installation. Some may be delayed but will not impact the machine installation (not as critical as magnets for first beam). Steve asked that the matter should be discussed in a special meeting.
• Follow-up of actions from previous meetings
  • Status of aperture model -> SR (pdf file)
    • Comparison with model from the official DB revealed the following differences: 
      1. Beam screens tilted by 90^o.
      2. Beam screen lengths at transitions.
      3. BPM replaced by beam screens in the arc.
      4. Errors for transition pieces of MQW's.
    • For beam screens several bugs revealed and corrected by S. Chemli. Wiggler beam screen was added by hand. Real beam screen dimensions are available. SF questioned the quality assurance for mounting the beam screens. This should be followed up in order to avoid potential errors (closing the loop between ABP and VAC).
    • BPM aperture model was updated (new types, reviewed by R. Jones and C. Boccard) and implemented in DB by S. Chemli. Markers at START and END for BPM MADX installation scripts.
    • Vacuum chamber apertures
      • Too much info in the DB, several errors (as reported also by JJ).
      • Systematic debugging is extremely time-consuming.
      • Semi-automatic script contracted with only essential aperture info for selected elements.
    •  A list of required MADX scripts was presented.
    • In conclusion:
      • No major errors with previous model (June 2004) used for collimation studies.
      • New model contains significant upgrades (aperture for all beams, BPM aperture, bugs fixed, warm element aperture, beam screen dimensions).
      • Model cross-checked with loss map simulations and also used with MADX simulations with no complains.
      • Follow up: Clear strategy of vacuum chamber markers. Essential info should be followed and communicated between ABP and S. Chemli. JJ will provide a list of points to be discussed with Sami. RA pointed out that the model should be frozen for simulation and the beam2 aperture model is asked by EP to calculate background around IPs.
• Status of LHC optics database and signs -> TR
  • For the Beam 2 model with field errors and correction, it was discovered that signs were changed in the triplet correctors. After talking with S. Russenschuck, it became apparent that polarity info may be essential to be included either in the MADX strength file or in the sequence file. SF, HB, MG and YP supported the second option, as the polarity convention for correctors (especially the high order ones) is not obvious and should be transparent in the machine model used in the control room. RA and JJ argued that this may create confusion and add complications in the sequence file. TR agreed to come up with the time-scale for  including the polarity convention in the sequence file.
• High-beta optics for IP1 -> HB (pdf file)
  • IR 5 TOTEM optics (β^* ~ 1540m)
    • Files available in  /afs/cern.ch/eng/lhc/optics/V6.5/Totem/ and documented in LHC-Project-Note-369 (A. Verdier).
    • Q8R5 and Q7L5 at min strength @ 7TeV.
    • Vertical tune with different integer part than nominal in collision (Q_x, Q_y)=(64.32, 58.31).
    • Only collision optics available (need optics for un-squeeze from injection + injection/ramp/"un squeeze").
  • Early (or diffraction) TOTEM optics (β^* ~ 90 m)
    • No official files. Working files in ~vrd/group/lhc/05/totem/diffraction/kdfb90, close to standard optics with same integer tunes.
    • Known issues (Werner Herr) at 90 m : separation bumps, correctors at the limit, problem with parasitic beam-beam (OK with 156 or fewer bunches), 25 ns excluded (75 ns feasible)
    • Need official files, with smooth path from standard injection optics (or end of ramp) to 90 m.
  • IR1 ATLAS high beta optics (β^* ~ 2540 m).
    • IR1 Atlas high-β, β* ~ 2540 m
    • Status (confirmed  by AV): No support from ABP-LOC (no doc., MADX files...).
    • Only some previous work by A. Faus - Golfe for IR5, probably same as IR1 (files copied  by Thys from /afs/ific.uv.es/user/a/afaus/public/atlas/  to /afs/cern.ch/eng/lhc/optics/V6.5/HiBeta).
  • Conclusion:
    • Consistent approach and follow up needed.
    • Aim:
      • Full set of files and tools (knobs) from injection to high-beta as for standard optics.
      • Sample jobs and documentation.
      • Official versions after discussion and agreement with experiments based on physics requirements.
      • Need to establish timescale and priorities.
• Sorting of main quadrupoles -> YP
  • Due to lack of time the presentation was moved to the next meeting.
• AOB

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