• Follow up of actions
  • Closed orbit correction in IR3 and cooling issues -> TR
    • Orbit distortion (simulated by means of dipolar field errors in MQWs + displacement of MQWs 1mm in both planes) are generated to evaluate the strength needed for orbit correctors in IR3.
    • In the case of dipolar field errors in MQWs, the maximum strength needed is less than 0.1T at 7 TeV.
    • A strength of 0.2-0.25T at 7 TeV is needed for the displacements in the quads of 1mm in both planes (the corrections achieves a reduction from 4mm peak orbit to 0.2mm). Hence, the previous estimate that the closed orbit correctors will be powered to 30% level is confirmed. 
  • Aperture analysis of the improved optics solutions prepared by TR -> MG
    • Comparison between old and new optics in IRs.
    • In IR2, the main effect is the diminishing of the peak dispersion on the left side of the IP for both beams. The 3 unit loss of aperture is not critical as it occurs in an area where there was enough margin (n1=13 before).
    • In the momentum collimation IR3 there are very small differences. JBJ comments that the difference in dispersion may influence the conditions of collimation. TR replied that the impact is small (Beam1 is slightly better and Beam2 is slightly worse). MG says that the collimation team should verify. SF comments that the difference should come from the change of the phase advance, as from Q6 to Q6 the optics is not touched. With respect to aperture, the new optics is slightly improved.
    • In IR4, there are very small differences for Beam1 and it seems that there is no difference for Beam2 (to be checked). There is a decrease of 4σ in the aperture of beam1 around Q9. The bottleneck is seen in Q8 (6.6σ). This may be an argument to use IR1 and 5 for adjusting the tunes.
    • For IR7, there is a big difference in dispersion of IR7, but the impact in aperture is small. Actually the situation has been improved for several bottlenecks.
    • In IR8, the loss of aperture is in areas where there was a lot of margin.
    • The missing part in the analysis of the gradients of MQTL which should not exceed the performance of some week elements.
    • The tuning of IR4 has to be assessed as well, i.e., it should be checked whether we are still in the inner part of the tuning range.
    • TR comments that at least in IR2, 8, 3 and 7 there may be an aperture problem at Q6 (6.9 to 6.5 in Q6L2 for beam2).
  • LTC actions -> MG (pdf file)
    • Following the presentation of YP at the LHCCWG, additional follow up for the VELO aperture in IR8 was asked, as well as the issues of time constant for the warm magnets for the spectrometer bump compensation. YP will finalize this in the next couple of weeks and he will report it back to LOC.
• Report from meetings
  • MEB -> MG
    • The level of 1000 approved dipoles and 300 approved SSS was reached.
    • An issue was raised for Q2 for which there is no working spare (as such a spare magnet feature a non-working quench heater). K.-H. Mess stated that the magnet cannot be considered installable in the tunnel and it can not be repaired (it is worth noting that the rescue facility at CERN will not be started up in the coming years). This serious issue was recorde in the minutes and the chairman of the MEB will report it during the LTC in order for the AB management to take note. SF suggests to focus on the spare policy of the US magnets as also the D1 spare magnet suffers from serious non-conformitites.
    • On the field quality side, the first Q6 for IR7 was presented and due to some problems with the supports, all 4 Q6 will have a vertical difference between the mechanical and magnetic axis of 1mm. We may have to find an optimal shift to trade off between mechanical aperture and the strength of the dipole corrector needed to compensate the kick from the displacement of the magnetic axis. At the injection level (measurements at cold) there is a b₆ of -43 units. For the other MQTL, the b₆ was measured (at warm) to be positive positive (about 7 units). However, it turned out that the warm mole is too short to measure the contribution from the magnet heads. Tests with a longer mole showed that the total b6 is essentially zero (heads and body contributions almost compensate). A new tracking campaign will be launched.
  • SLM -> MG
    • News on contract policy will be announced in the next group meeting.
    • There are several discussion on the new policy of non-resident allowance. On the career evolution side, the DG proposed to speed it up at the beginning of the career and than saturation.
    • Interested participants in PAC07 should make a request before submitting abstracts.
  • FQWG -> MG
    • The follow-up on the measurement  program of MQM and MQY quadrupoles was presented and discussed. A cross-calibration between magnetic measurements at Block 4 and SM18 is required. The issue of magnetic permeability for the laminations of the MQY makes this task rather difficult. MG asked at the meeting to put all efforts on this topic, as the knowledge of the transfer function for MQYs has a strong impact on beta-beating at injection. JPK will report on the status of the cold magnetic measurements of insertion quadrupoles at a future LTC meeting.
  • LHCCWG -> MG
    • Presentation of YP on IR bumps (see previous point).
• Draft presentation of LOC activities at ABP Group meeting -> MG
  • The presentation reviews the several activities of the section (Magnet, LHC commissioning, LHC optics, MADX on-line model, software tools and collimation).
• Issues with IT support -> FS
  • Due to the staff problems in IT,  a lot of support will be canceled  (including FORTRAN, MATHEMATICA, etc), but without concrete information.
  • Oliver is informed and is following up this issue.
  • The problems encountered with CASTOR have been analyzed and Eric McIntosh will provide a new version of the tracking environment to take into account the improvements.
  •  Boinc will be discontinued and CPSS is in an unclear state. The needs for tracking from collimation, upgrade and LHC commissioning have to be reported to Oliver. Documentation is needed for the new tracking environment.
• AOB
  • The CVS repository of the optics file has been constructed by FS and TR. Only optics versions starting from V6.4 will be included in the repository. Of course, the files will be always available under afs.
  • RWA asked about the transverse position of collimators in the ring depending on the position of the beam. Following the discussion it is decided that:
    • The collimation team (TW) will provide a script to install the collimators in the official V6.500 LHC sequence.
    • TR will generate a survey file that will be stored in the official repository under afs for further use.

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