Presents: RA, CB, SF, MG, JJ, AK, RdM, SR, TR

• Follow-up of actions from previous meetings
  • Correction of aperture database (Action: TR, MG).
    • MG reports that S. Chemli presented the status of the database concerning aperture:
      • Beam screens of Q3 were wrong since the removal of the TASB. The length at warm from the vacuum group (CDD drawings we decoded) was wrong. This is now corrected and there should be no overlaps between Q3 and the DFBX. LSS3 had been re-entered in August, LSS7 is still out-of-date, LSS8 is currently being re-entered.
    • Given this situation, it is decided to wait until the status of the database is improved, before making any additional attempt of data extraction.
  • Verification of the aperture in IR8 (Action: WH, JBJ).
    • Verification still pending.
  • Additional check of the electrical drawings for point 8 (Action: MG).
    • MG reports that the drawings concerning the electrical circuits for IP8 are ready as well as a revised version of the list of conventions for the polarities prepared by S. Russenschuck.
    • The material will be distributed to the people responsible for the various classes of magnets for verifications.
    • P. Proudlock will be contacted to understand the details of the generation of the electrical drawings from the official database. (Action: MG).
• Report from meetings
  • MEB -> SF
    • approval of cryodipoles for sector 3-4 is in progress and allocation of cryodipoles for sector 4-5 will restart soon.
  • LTC -> RA
    • A discussion on the quench limits for cryodipoles with lead ions led to the conclusion that the 4.5 mJ/cm3/s is very likely too conservative (even though no consensus was achieved among experts).
    • A discussion of the emittance blow-up induced by beam measurements led to the conclusion that such a blow-up is probably negligible.
• Optic squeeze generation using a new Newton-Raphson based matching routine in Mad X -> RdM (pdf file)
  • The routine was developed to deal with the matching and the squeeze sequence for a novel layout of LHC interaction region.
  • It allows dealing with different types of constraints, both on the matching variables and on derived quantities.
  • It proves to be powerful in particular for the computation of the squeeze sequence.
  • The routine will be part of the new release of MAD-X
  • It is proposed to test the routine to improve the squeeze sequence for IR8.
• Discussion of the Commissioning preparation meeting at the next LTC -> MG
  • An account of the on-going discussions were given by OB at the LOC meeting held on 15/03/05.
  • The organisation of the LHC commissioning was based on a scheme presented by R. Bailey at the ABMB and LHCOP. It foresees: Machine Co-ordinators (3-4), Commissioners (many from ABP-LOC), EICs (from OP).
  • A brainstorming discussion is scheduled for the LTC meeting to held on September 7th: there, a revised version of the organisation for the commissioning will be presented.
• AOB
  • RA reports about the results of the collimator flatness after the tests in 2004. The specifications are between 0.040 mm to 0.050 mm. After the tests the flatness was degraded between 0.200 mm and up to 0.300 mm. Indeed, the metallic support (copper) is deformed, but not the jaws. A solution is at hand, i.e. replace copper with an appropriate alloy. Analysis of the impact of the measured shape of the collimators on the collimation efficiency are in progress.
  • TR reports that the crossing angles in the official optics database have still to be fixed. A new version of the MAKETHIN command, which works fine, is ready, but not in the official release of MAD-X. Waiting for the new MAD-X release the following files were provided to the users: Instructions are added to the README file of directory /afs/cern.ch/eng/lhc/optics/V6.5:
    • New THIN sample jobs:
      • job.sample.thin.new.madx to be used ONLY with MADX versions later than June 2005. Slicing is done on-line and numbers of slices are as in V6.4.
      • job.sample.thin.madx temporary version using a THIN sequence, no on-line slicing (to be replaced by the above sample job when the next MADX version will be released).
    • They produce the same thin LHC machine.
    • The slicing file used in the first job contains a patch to 'reproduce' a bug originating from V6.4 (all thin strength files were made with this bug present).
    • A slicing file without this bug is already available for future LHC versions in V6.500/toolkit/slice.madx. As the bug concerns the MQWB.5xxx (2 slices in beam 1, 1 slice in beam 2) the insertions 3 and 7 require slightly different quadrupole strengths in beam 2.
  • FS reports:
    • MAD-X version 3, which will include PTC and the new version of the MAKETHIN command, will be released in few days.
    • A MAD-X Day is schedule for September 23rd.
    • A problem with SixTrack (compilation) is fixed now.
    • E. McIntosh will leave already by the end of 2005. The new release of the scripts to run SixTrack is ready and a Forum should be organised soon. The issue of computing support for ABP is rather urgent and serious.