Presents: RA, OB, HB, SF, MG, JJ, AL,  GRdM, TR, SR.

• Follow-up of actions from previous meetings
  • JJ (aperture model): the tool was upgraded to cope with the requests made at the last LOC meeting. Cross-check with model maintained by CWG to be done. S. Chemli will fix few problems in the official database and he will provide the data for the vacuum chambers (pdf file).
  • MG (magnetic cycles for insertion quadrupoles): gradient vs. time were computed for IR5 (IR1 is the same) and IR2 during the squeeze. The squeeze for IR8 should be improved (Action: TR). Further discussions with F. Bordry are needed to verify the assumptions made for the power converters. Analysis of the dynamic effects should be pursued. (pdf file).
  • FS (magnetic data of triplet quadrupoles): serious problems with data for single magnets (not coherent with those for the whole assembly). R. Ostojic will provide validated data to FS by the end of April.
• Report from meetings:
  • SLM -> OB
    • Deep changes in the AB Department Management will occur in the forthcoming months.
  • MEB -> SF, MG
    • 2 cryodipoles are missing to complete sector 7-8
    • 30 cryodipoles are missing to complete sector 8-1
    • Delay in the MEB approval of SSS is mainly due to issues related with measurements of the SSS axes (geometric, magnetic).
  • TCC -> JBJ (minutes, installation schedule)
  • FQWG -> SF, MG
    • A presentation by SF and MG reviewed the assumptions used to compute the effect of the various sources of beta-beating at injection. Sextupolar pool piece misalignment is no more a source of concern. Insertion quadrupoles have a strong impact on beta-beating, which is dominated by MQX.
  • InjWG -> HB
    • Activities in TI2 were presented (TCDI). Work on the optics of the TI2 transfer line is on-going.s
  • MP Review -> HB
    • It will take place after Easter. Contributions from ABP are expected (RA, HB, GRdM, SR).
  • CWG -> RA
    • Final locations of collimators will be frozen by next week (95% already defined).
  • News from the collimation project -> RA
  • Workshop on "Beam-generated heat deposition and quench levels in LHC magnets" -> RA
    • Important conclusion for ABP MEB activities: quench performance classes are not relevant for cryodipoles sorting.
    • It is dangerous to operate a magnet near its quench limit: this will reduce drastically its lifetime (about a factor of three).
  • CARE-HHH-APD mini-Workshop on "Crystal Collimation in Hadron Storage Rings" -> RA
    • Crystals will be installed in the LHC and tests with beam will be made.
    • There is a strong push by W. Scandale to resume Crystal experiment in the SPS.
• Organisation of the LHC commissioning -> OB (pdf file)
  • A revised version of a paper prepared by R. Bailey is presented. Feedback can be given until next US-LARP meeting. Further discussions (if necessary) at next meeting.
• Latest results for the DA vs Q' and tune variation -> OB (pdf file)
  • This study allows revision of the tolerances for the Q' values.
  • The tune scan and part of the simulations should be done for the more complete model used for the insertion quadrupoles' studies.
• Follow-up of correctors' field quality -> AL
  • MO shows 100 units @ 17 mm of b1 on 10%-15% of the whole production. Effect at collision (full strength) is about 30 mum. It is correctable, but change of MO strength will entail a change in CO (tolerances for collimators settings are extremely tight).
  • FQWG asked for the accuracy on the knowledge of the transfer function for correctors in order to define the measurement strategy. Collection of observables and measurement accuracy is on-going to answer the question.
• Follow-up of the Dynamic aperture studies for MQY quadrupole magnets -> MG
  • The tracking campaign is finished: data have to be analysed. A detailed presentation will be made at next meeting.
  • In the meantime the scanning of the skew multipoles for MQM-like quadruples will be resumed.
• Status of the optics database -> TR
  • V6.5: data from squeeze are already stored in the official database. The new values for IR8 matching will be put there.
  • V6.500 (i.e. the official release of the new LHC sequence): available. Only difference with respect to V6.5 is the sequence: strengths are of course the same. Within few months all the tools (error routines etc.) should be made available also for this version..
• Status of computing for LHC studies -> FS
  • CPSS is now available for numerical simulations
  • New versions of scripts for running MAD and SixTrack are available. Improvements are expected in few weeks.
  • Disk space issues are being tackled.
  • Strong support from E. McIntosh (IT) is crucial for LHC computing.
  • A statement of the importance of the support form IT (and the need for support once Eric will retire) is being prepared (to be sent to IT Dept. Head via AB Dept. Head).
• AOB

Colour code:

• Black: proposed agenda
• Red: outcome of discussion at the meeting