• Report from meetings
  • MEB -> MG
  • A problem occurred with warm quads field quality. They will be discussed during next meeting.
  • LTC-> MG
    • Crisis with objects inside the beam pipe, observed by technique from T. Kroyer and F.Caspers.
    • Next LTC for issues of the 450GeV commissioning, with talks by SF, MG and RA.
• Status of the optics database -> TR
  • New error routines available, with ability to use combination with statistical and measured errors and cleaner structure.
  • In the triplet correction, an accidental change of names in the power supplies and correctors triggered SF routines not to work anymore for V6.500. This is now corrected.  A discussion is followed regarding the name conventions. Normally the old names will be used with the next version unless hardware issues will impose to change the name.
  • Some problems were discovered with triplet corrector polarities of the database. MG mentions that there may be an issue, as old polarity conventions were used for the approval of drawings. TR said that this was followed up with S. Russenschuck.
• Status of the MADX on-line model -> FS
  • Central communication with the control system through SDDS and SDDS converter is ready as a part of MADX (but not of the standard release due to copyright issue of the SDDS part).
  • Data from MADX can be offered in desired format.
  • SDDS browser was set-up and it can now be used in the controls environment.
  • Possible fellow candidate was found and gives a talk this week.
• DA studies for collisions at 450 GeV -> MG
  • Summary results for three configurations: standard injection, and two optics devised by SF: β* of 6 m (round beams), and β* of 6/3.7 m (flat beams)
  • Average DA and spread is very comparable, but below 10σ for 15^o and 30^o.
  • Next step is try to correct with triplet correctors.
  • Spool pieces off in 50% of the machine and DA for the two optics is compared. SF argues that this is not realistic because the spool pieces that are missing should be driven in order to correct the chromaticity. The use of the chromatic sextupoles to compensate for the missing spool pieces might induce a very large local β-beating if combined with closed orbit distortion.
  • SF points out that the V6.4 and V6.5 optics have remarkably comparable DA w/o taking into account the b6 and b10 hysteresis effects in MQM and MQY magnets (see EPAC paper and LOC minutes 28/03/06 for a detailed analysis of the hysteresis effects for insertion quadrupoles). On the other hand the present results seem to indicate the hysteresis effects indeed lead to a drop of the DA by 1s for V6.5 bringing it to 9.5sigma. SF expresses his concern for this results and will check in more detail, in particular to his code, written for V6.4, to see whether the DA reduction is not an artifact due to the new and more uniform slicing protocol adopted for the LHC V6.500 for MQM/MQY.
  • FZ questions if there is any chance to correct the effect and SF replies that this could be achieved by using special de-magnetisation cycles for MQM and MQY. However, this would have an adverse effect on the transfer function.
  • DK asked which error table is used and MG replies that this is 0605 available form the official database.

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