Summary notes of the LCU meeting on 15/10/2013

Present: RB, HB, RdM, LD, OD, MHF, MF, MG, PH, JJ, ALan, BR, AS, MS, RV, FZ

Report from meetings

• SLM and general information -> MG
  Welcome back to Pascal Hermes who will work with Roderik Bruce as doctoral student.
  Octavio will defend his thesis in two weeks.
  Concerning the selection of fellows and students, it was decided to advance the student committee from 2014 on to January and June.
  The organization of future circular collider studies FCC is being set up. The studies will be led by Michael Bendikt with Frank Zimmermann as deputy. For further information see the talk by Michael at the recent TLEP workshop. The structure has been approved by RECFA and working groups are being set up.
• MAD-X status -> LD
  The server for MAD-X testing is up and running. The last MAD-X production release was from May. A new release will come soon and include bug fixes, the new makethin (leaving for the moment previous defaults), and optional thick tracking for quadrupoles. About 2 weeks after the production release, it is planned to update natural constants to 2012 standard values in a separate release to allow for comparisons. 
• SixTrack status RdM
  Massimo said that batch production was slow, due to saturated job queues on lxplus by experiments. IT was informed. We could get dedicated resources, but this would be difficult to set up and maintain. IT said they increase general resources and the situation would improve. Massimo proposed to move temporarily from SSC6 to SSC5 which is less used.
  The wire compensator will be added as a new element to SixTrack. Riccardo suggests to also add this as element to MAD-X and the converter.

Update on TAN aperture model and aperture margins for the HL-LHC upgrade -> MF (slides)

Miriam presented an update of TAN aperture models for the HL-LHC. In MAD-X, the present TAN was simply represented by a 26 mm circular aperture of a very limited set of markers. Much more information on the TAN is available from the layout database. The beam pipe is a y-like shape in the TAN region, going from a single beam pipe to two beam pipes for Beam 1 and Beam 2.

For aperture, the region between D1 and D2 with the transition from one to two beams is tricky. Three sets of aperture files describe the aperture model.

The first level defines aperture for magnets and is extremely reliable, being checked in detail during the MEB activities. Experimental chambers are added on the second level and have been generated by Massimo, using the drawings. Different models are given in order to reflect the planned upgrades. The detailed vacuum layout is introduced in the third level. The detailed vacuum layout information should be used with care and may have issues.

The layout database does not yet have aperture information for the HL-LHC, which therefore has to be put in by hand.

Miriam has made a more detailed aperture model for the proposed TAN for the HL-LHC. Files are available from  /afs/cern.ch/user/m/mfittere/public/HLLHCV1.0PIC10102013 with in particular  aperture/aperture_upgrade_TAN.madx. Further details are given on the slides. In addition to apertures, information is required on tolerances. It will be requested that the layout database includes additional markers to provide more detail on the TAN layout.
There was a discussion which tolerances and also which target beam energy should be used. A normalized emittance of 3.5mm is used to express apertures in units of sigma. Massimo confirmed that the reference beam energy for the HL-LHC is 7 TeV.

AOB 

None

Last update: 28-October-2013

MG & HB

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