Summary notes of the HSS meeting on 07/07/2014

Present: HB, RDM, MF, MG, PH, ALan, GR, BS, PS, CT, RW, TP

Report from meetings

• SLM and general information -> MG
  The LTEX and LEB working group were recently joined into a new working group TREX, chaired by Mike Lamont. One item on the TREX agenda is the request for a reduction of beam pipe dimensions by ALICE.
  The LMC this week will review the LIU and HL-LHC baseline, after the approval by Council (with some budget constraints).
  The LHC beam energy for 2015 will be at maximum 6.5 TeV.
  Specifications on ripple tolerances for power convertors for the HL-LHC are studied by Miriam et al and will be discussed in one of the next HSS meetings. The PS is in recommissioning; physics will start soon.
  As reported in earlier meetings, the ABP-group BBQ was postponed to September, details remain to be fixed.
  LHC optics after LS1 preparations including ATS compatible are in full swing. As discussed in the meeting on 12/5, one concern is a possible loss in cleaning efficiency. Another subject are the use of octupoles to mitigate electron cloud and implications on the dynamic aperture. An LMC is planned for the 20 August with a discussion of optics after LS1.
• LBS -> HB
  Slides of the last LBS meeting on the 16 June can be found on indico, including a presentation on considerations of failure scenarios w/o TAS.
• MAD-X status -> GR
  Ghislain said that MAD-X 5.02.02 was released few days ago, that many bugs were fixed and that strongly encourages us to use this latest version. Fixes and cleaning were also done in the PTC part by Piotr. The work by Andrea Latina on thick tracking should be discussed and finalized soon.
• SixTrack status -> RdM
  Riccardo said the work and discussions continue, but that there would be nothing special to report this time.
• MAD-X online model -> PS
  Piotr said there is good progress, in particular also on the aperture meter, which up an running again. The LHC control system is currently not operational, so that real online testing cannot yet be done. Tobias Persson works with him, mostly on optics for injection.
  

Aperture for new Alice beam pipe after LS2  -> MG (slides)

The inner radius of the central beam pipe of ALICE as originally planned and currently installed is 29 mm. ALICE has requested a significant reduction in the beam pipe dimension with proposed installation of the new reduced beam pipe in LS2.
First requests were for a reduction of radius over 5 m length and turned out to be much too tight for our standard criteria. ALICE now agreed the a reduction of just the central part should be sufficient.
Massimo studied the requested and required apertures including improved tolerances in terms of n1, see his slides. The new model will be made available in the as-built aperture subdirectory on afs. This triggered some discussions on naming of files to reflect changes in the LHC with time.

Helmut commented that web references for filling schemes have now subdirectories Run1, Run2,  as can be seen here. He also reminded that approval for beam-pipe reductions are for the LHC and that longer term work including crab cavity failure scenarios is in progress for the HL-LHC.

AOB 

The next meeting is planned for the 4 August.

Last update: 8-July-2014

MG & HB

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