• Follow-up of actions from previous meetings
  • Status of LHC aperture model -> SR
    • Beam screens
      1. No engineering specification available (MAD file data sent by Samy).
      2. Not particularly big difference but for separation dipoles (up to 0.5 mm).
      3. Waiting for Samy for final approval.
      4. Temporary files with two headers (with/without tolerances), even if it is not a good idea to work on this file, as it will evolve.
      5. JJ asked for the final file for the work of GB on the collimation line of  I-LHC
      6. MG proposed to wait for the final approval by Samy, in order to avoid mistakes. Then the version should be frozen.
  • Status of LHC optics database and magnet polarities -> TR
    • Database people are in favour of including magnet polarity conventions in MAD sequence file..
    • The time needed for applying the changes is a few days and a few weeks will be needed for debugging.
    • Two versions of optics version 6.501 will be built: one with old and one with the new convention, in order to proceed to a detail comparison of the two, and the final release.
• Report from meetings
  • MEB -> MG
    • A long list of dipoles for sector 5-6 was approved.
    • SSS and SpSSS allocation was continued.
    • For ensuring that the beam screen orientation is correct on the SpSSS (depends on b1/b2 and connection orientation), a photo will be taken when they are mounted. A table from JBJ will be given to SMI2 to close the loop between ABP/LOC and AT.
    • IR quads will  be discussed on today's MEB.
    • JBJ asks JJ for providing the missing option for displacing transversally the IP in IR2 to increase the available aperture and then update the aperture tolerances in view of triplet approval (Action: JJ, deadline two months).
  • FQWG -> MG
    • A memo was produced and endorsed with the proposal of reducing the AC mole measurements to 20% of the remaining SSS.
    • A list of the critical magnets to be measured was provided by YP to the SSS coordinator magnet (M. Modena)
  • SLM -> MG
    • Revised AB/AT committees
      1. LTC will evolve to LHC performance committee.
      2. APC will remain as the committee discussing performance issues up to the SPS.
      3. ATC will be revived with F. Bordry as chairman.
      4. ABOC will continue.
      5. ABIC will cease to exist.
    • Working groups:
      1. FQWG will finish as there is not any possibility to influence production anymore.
      2. For WGA, JBJ asked for its continuation in 2006 as it is the only official way to influence the geometry of hardware, but can be stopped in 2007.
    • "Habilitation Electrique".
      1. From now on, anyone involved with operation (SR), machine supervision (GB, YP) or LHC commissioning (RA, SF, MG) has to pass the course for obtaining the "Habilitation electrique".
      2. A crash programme will be organized for the group.
      3. SR questions if the new safety rules will impact the commissioning work of the collimator team.
• Issues with IR6 -> MG
  • Values lower than 3% of the nominal powering were found by SF for the IR quadrupoles at Q8L6 and Q8R6.
  • TR confirms that these bounds were not taken into account during the matching. In particular, 2 quads are at 2.5% of their nominal strength, and their retuning to acceptable levels induces aperture limitations.
  • F. Bordry, on the other hand, confirmed that the 2.5% current level can be still accommodated and requested the final values.
  • JBJ comments that the aperture of the septa is not included in the database of Samy. A special sequence exists (SF) based on an old optics version (before 6.5). SR mentions that an automatic script for building the septa aperture exists and it can be used to do calculations with the new optics version.
  • SF comments that a new sequence should be built including the imposed current bounds. TR asks about the magnet types which need to have these bounds. SF replies that only MQT and MQTL magnet can go below 3%.
• Sorting of main quadrupoles -> YP (pdf file)
  • YP reminded the strategy used for sorting the MQs, using the 2nd order resonance driving terms.
  • For the 4 last sectors (5-6, 6-7, 2-3 and 1-2), 4+4 coefficients (h/v, Beam 1/2) were minimized corresponding to the b2 of the raw warm measurements and its extrapolation to cold, after the permeability effect disappears.
  • Several other optical properties were controlled during the sorting (tune-shift, peak beta-beating and dispersion).
  • For Sector 5-6, 12 SSS with collars featuring high magnetic permeability were already pre-allocated (10 paired and 2 marginal cases) and 10 SSS of 3 different types have not beam assembled by ACCEL.
  • The final results after sorting, reduce significantly the beta beating (0.3% at the sector exit for the realistic case and less than 1% for the raw b2).
  • Peak beta beating within the sector is always less than the specification (2.7%). SF questioned the representation in the same figure of rms and peak values, which may induce confusion. YP agreed and applied the corrections to the final version of the viewgraphs.
  • The rest of the sectors will be discussed in one of the next meetings due to lack of time.
• Sorting of warm D1s -> MG (pdf file)
  • MG presented the status of D1 dipoles and the analysis of their magnetic measurements.
  • Magnet 9 has a b1 quite different from the rest.
  • A flip-flop strategy was adapted for the correction of the orbit distortion and parasitic dispersion.
• Field quality issues of MQTL quadrupoles -> MG (pdf file)
  • MQTL presented ad number of quench performance and field quality issues. Both problems were treated (list of magnets with less demanding currents and production of error tables + tracking).
  • Latest production showed some problematic MQTL in terms of field quality (b3, b4, a3, a4 b3, b4, a3, a4) and target field errors used to qualify the magnets weres the one specified for the MQTs. Crash programme for the impact of the actual field quality on the LHC DA.
  • Two cases were considered for the FQ from the magnetic measurements at warm: one excluding and the other excluding the outliers.
  • Results of preliminary DA computations indicate that the measured field quality has a marginal impact (outliers to be considered on a one-to-one basis).
  •  Additional studies needed for impact of closed orbit (feed down).
• AOB
  • SR mentions that he received a lot of request for collimation studies for final TOTEM optics. From the Physics point of view, optics is finished and a version is used for their calculations.
  • MG replies that their calculations are based on beam transfer along the IP, and any optics (even the one with the strange integer tunes) can be used without problem. For multi-turn tracking though, the problem of tunes has to be solved and a final optics has to be produced (HB is is in charge).

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