Summary notes of the LCU meeting on 30/06/2009

Present:  MA, CB, HB, MG, WH, BH, JJ, YL, JM, JN, FR, AR, FS, RT, GV, SW, XAGKONI Athanasia

Report from meetings

• SLM and general information -> MG
  MG started with general information on the LHC. Reinstallation after the incident is completed. Half of the machine was warm and splice resistances measured. Sector 4-5 was warmed up recently and is currently being measured.
  A complete update will be given by Steve Myers in a special presentation on the 2nd of July.
  A new LHC Tunnel and Experiments Study Group (LTEX) was created recently and had its first meeting on how to secure the caverns in case of massive loss of Helium. A 2nd meeting of the LTEX on the 29 June was on the BRAN and LHCf. HB was asked to attended this meeting where he reminded that the LHCf experiment in fact interferes with the BRAN commissioning and absolute luminosity calibration as discussed in LHCCWG#4 and that the statement agreed in the LTC#54 should be respected to minimize this interference.
  There has been a follow up to improve on the aperture model and tolerances in MAD-X. MG showed a comparison between Stefano's aperture model and MAD-X aperture for IP5. The new agreed total mechanical tolerance for the four experimental beam pipes is 11mm.A global file with the description of the experimental pipes and the mechanical tolerance together with a seqedit file is being prepared by MG: once ready the files will be stored in the official optics database.
  JLN helps to provide tools to compute aperture.
  JJ is following up on the aperture of the Y-chamber for IR2.
  HB reported from the EDS conference on forward physics which currently takes place at CERN and said that there is a strong interest for early operation with beta*=90m.
  A general ABP group meeting is scheduled for this Thursday.

Update on CMS solenoid stray field -> YS (slides)

YS reported on modeling of the measured CMS solenoid stray field. With the latest results from the magnetic simulations, the field at the triplets interconnects can be approximated (to a high accuracy) to a pure solenoid with fringe field. This rules out the concern about possible non-linear effects.
YS and FS are working on an implementation of thin solenoids in SIXTRACK together with the fringe field.  Thick solenoids could be defined as well.
YS had a first look at effects with MAD-X at top energy and found no significant impact on the coupling. He tested also the impact on DA, but as expected (there are no additional non-linear field induced by the new solenoids) no reduction is observed. HB said it would be more relevant to study solenoid effects at injection.

AOB

FS said meetings on the MAD-X online model resumed with meetings once per month and that the on-line model was successfully used in recent TI8 tests. The consistency of settings can be checked by extracting values from LSA and feeding them into the online model.

FS is preparing a memo for IT on what would be required and appears currently be missing on the new LINUX version SLC5.

MG introduced the summer student XAGKONI Athanasia who works with FZ on particle dust interaction in the LHC.

Last update: 03-July-09

MG & HB

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