Presents: RA, CB, OB, HB, SF, MG, JBJ, JJ, AL, SR, TR, GRD, FS, KZ

• Follow-up of actions from previous meetings
  • Field errors for triplet magnets -> MG
    • FQ of the magnets ready for MEB discussion is available, as well as geometry measurements.
    • DA aperture studies at injection are in progress.
  • Update on the MQTL -> MG (pdf file)
    • A preliminary analysis was already presented (see LOC meeting 26/04/05).
    • The change of material of the central post seems to solve the performance issues.
    • The evaluation of the strength requirements for the various optical configurations has been completed: even though some location might be compatible with a reduce MQTL performance, this might have serious limitations on the machine performance. On the other hand rejection of magnets could delay the installation.
    • The situation should be presented to the LTC after collection of:
      • official statement from AT-MEL that the poor training performance does not imply higher-sensitivity to beam losses, i.e. high number of beam loss-induced quenches
      • official statement from AT-MEL that the magnet lifetime is not considerably reduced by the quenches due to the mechanical instability.
      • the definition of a procedure for the follow-up along the whole process of the magnet manufacture till the assembly completion (in an SSS or a Q6 module) of the slot allocated on the base of the performance of the MQTL magnet.
  • Magnetic cycles for insertion quadrupoles -> MG
    • The preliminary version of the magnetic cycles for insertion quadrupoles (see LOC meeting 15/03/05) have been communicated to AT-MEL to use them in Block 4 in the context of magnetic measurements.
• Report from meetings
  • LTC -> OB
    • The issue of aperture kicker was considered: new power converters will be purchased to limit the available kick amplitude. Energy and intensity measurements are crucial to provide a safe system: discussions are on-going on how to implement a SIL3 intensity measurement requires still some discussions.
    • The draft schedule of machine operation in 2006 was presented: there are two weeks with machines in stand-by mode in October/November. The LHC sector test will take place by end of November.
  • LHCOP -> OB
    • Remote operation scheme was discussed.
  • ABMB, SLM -> OB
    • The decision has been taken to install H/V scrapers in the SPS, but no skew ones. However, these devices (former ISR scrapers) are meant only for MD use! Of course, this limitation is not acceptable. LHC-type scrapers could be used as a basis for new SPS scrapers.
  • FQWG -> SF, MG
    • Discussion on the progress of the MADX model. TR has developed the tools to assign measured errors to already allocated small-series magnets, such as cold D1s, D2 and MQXs (whenever their position will be defined). No detailed test was done so far. As soon as the data from MTM database will be made available, also dipoles and quadrupoles will be included.
    • There are still difficulties with the magnetic permeability of the MQs.
  • MEB -> SF, MG
    • Cryodipoles' allocation in sectors 7-8 and 8-1 is finished with the exception of 1+1 magnets waiting for further tests or measurements.
    • Discussion of cryodipoles for sector 4-5 is starting.
    • Crisis with magnetic axis measurement of SSS is over and SSS approval will be resumed.
  • INJWG -> HB
    • Detailed FLUKA computations for TDI were presented.
    • Issues induced by trapped modes in the TDI were investigated. This should require an in-depth analysis (as it was done by RLC experts for LHC ring collimators).
    • RA expressed some concern about the fact that cooling is not foreseen in the present design. It is agreed that this issue be discussed at the CWG, were a solution should be agreed, before reporting the final conclusions to the LTC.
    • The need of a thin Ti window at the end of TI8 was discussed: the emittance blow-up is about 1.7 % (V-plane).
    • The assumed emittance budget of 7 % (SPS extraction-LHC collision) is considered to be very tight following the studies on emittance growth and tail repopulation during transfer and injection.
  • CWG -> RA
    • Installation strategy: in case of late delivery of the collimators do they have to be installed according to the installation scenario or on the basis of their relevance for machine cleaning? The best strategy seems to be:
      • install collimators according to the official installation schedule (such a decision should be endorsed by ATB)
      • in case of difficulties, it will be still possible to displace the collimators already placed to the locations critical for the machine protection.
    • The various options will be presented at the LTC for final approval.
    • Primary collimators are now 60 cm long in the whole ring.
    • Phase II: SLAC strongly committed to the studies for the upgrade of the collimation system.
    • Review: another review is foreseen to be held in Fall or winter this year.
• LOC Section mandate -> MG (pdf file)
  • A draft version of the mandate for the LOC section is presented for comments. This will be a part of the LOC presentation at the General Group meeting on Wednesday 29 June 2005. The final version will be available in the LOC web site.
• TI2 optics -> HB (pdf file)
  • The final optics TI2 is ready: the layout change concerns the movement of Q13 by 1 m.
  • The integration check will be launched. Then the layout drawings and the survey data will be updated.
  • The layout is flexible enough to match the ring optics with 20 % beta-beating. In this case the phase advance between the collimators will be slightly less favorable than for the nominal optics, but still acceptable.
• Effect of b5 spool pieces failure on DA -> FS (ps1, ps2, ps3, ps4, ps5)
  • Previous studies were made by F. Schmidt and G. Xu using LHC lattice V4 and by M. Hayes using V6.2 optics and 9901 error tables.
  • A new study was made with V6.4 optics and a new set of error tables, based on the measured field quality for cryodipoles and errors in quadrupoles from the 9901, and separation dipoles D1 (cold) and D2.
  • The results of the two studies agree: the degradation of DA due to the failure of the b5 spool piece circuit in one octant is small and it does not depend on the octant. By compensating the missing circuit with the remaining seven initial DA is recovered.
  • For this study, DA is computed using 50 angles instead of 5 used in the standard protocol. The factor of 10 in angles turns out to give a DA value smaller by 10%.
• AOB
  • New visitor in LOC section: K. Zang
    • FS introduces KZ who is supposed to spend six months in LOC section working on PTC integration in MADX>
  • Special optics for CMS -> MG
    • Following the announcement made at an international conference that an optics for Totem with beta*=170 is available and it can be used with nominal beam, a paper is being prepared by W. Herr to show that such an optics cannot work with nominal beam parameters and to define the accessible set of parameters for this type of fancy optics.
  • Status of aperture model -> JJ
    • No progress so far.
  • Issues with the MQ field quality -> AL
    • Concerning the issue of out-of-spec magnetic permeability of the collars of the MQs, it was decided in a special FQWG meeting to identify the magnets and install them in SSS, which will be paired in the arc to guarantee the proper compensation. This approach was properly followed-up by AL in co-ordination with T. Tortschanoff.