Summary notes of the LCU meeting on 05/03/2013

Present: RB, HB, RdM, LD, OD, MHF, MF, MG, PH, BH, JJ, LL, SR, GR, RT, AV RV

Report from meetings

• SLM and general information -> MG
  Welcome back to Miriam, who re-joined us this month as fellow to work on HL-LHC in the framework on WP2 activities.
  Massimo said he is preparing for a meeting on the optics after LS1. Our responsible for the optics database is now Riccardo.
  During LS1, the LMC meeting be less frequent and alternate with the IFC meeting on injectors and meetings on LS1 coordination.
  A machine protection workshop takes place close to Annecy from 10-13 March, see indico. The same week there will be a CMAC with contributions from us and the LHCC with Helmut as member from the accelerator sector. Rogelio is considering the planning of a workshop on hardware improvements for optics measurements during LS1.
• MAD-X status -> LD
  A generic mail address mad@cern.ch is available for support. Ghislain is helping with follow up. There have been discussions on the follow up for LHC@home. IT downs not want to support BOINC on the longer term, as it is not a standard open source project, but will continue to provide help on servers. Helmut said he is implementing the option for thick slicing of selected quadrupoles in MAKETHIN and has provided a first test version checked presently by Thys. At the same time he is reorganising the code to make it more readable and efficient using in parts C++ standard library features for string handling keeping track on which elements are sliced how. Laurent said that using C++ in MAD-X would be ok for special justified cases like MAKETHIN but should not become a general trend.
• SixTrack status -> RdM
  Riccardo said they now have an early draft version for a manual describing what SIXTRACK is supposed to do. One of the main users of SIXTRACK is the collimation team. They use a lot of platform dependent post processing which makes it incompatible with LHC@home, which Stefano thinks is not a problem since they have access to adequate computer resources within CERN. Massimo and Riccardo say that LHC@home would typically offer 10 times more CPU than what would be available with LSF. This can be used for example to increase standard standard tracking from 1.e6 to 1.e7 turns. Laurent remarks that tablet computers become increasingly popular these days, resulting in a decrease on the long term of PCs suited for LHC@home.

Summary of considerations for vertical crossing angle in IR8 -> BH (slides)

As discussed in previous meetings, the larger horizontal internal crossing angle of +/- 2.1 mrad generated by the LHCb spectrometer makes it difficult to keep sufficient separation at 25 ns for one of the two required spectrometer polarities. This could be avoided using a vertical external crossing angle which is currently limited by the beam screen. There is no time to rotate the beam screen in LS1. Bernard showed to which extent a vertical crossing angle would fit for the current beam screen rotation depending on assumptions on emittances and tolerances. See the slides for details. Stefano will discuss that consequences on the change of the plane of the crossing angle with MPP and will report back to agree on the message to carry across to the LMC.

AOB 

A meeting in two weeks would interfere with the beam-beam workshop, and Tuesday in 3 weeks with the HL-LHC parameter and layout committee. It is planned to organise the next LCU meeting exceptionally on Monday the 25 March.

Last update: 25-February-2013

MG & HB

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