Summary notes of the LCU meeting on 22/05/2013

Present:  RB, LD, OD, SF, MG, BH, JJ, EQ, GR, MS, RT, AV

Report from meetings

• SLM and general information -> MG
  Massimo commented that conferences should not be used to publish papers, but rather to exchange information with colleagues. New results should be published in peer-reviewed journals, even if the efforts to prepared a good journal paper are not the same as for preparing a conference paper.
  It is reminded that the KT Day sis being organised on 3/6.
  The Group meeting is being organised on 19/6: the presentation by Oliver will be followed by short presentations by the SLs and a BBQ. Ten volunteers are needed to help setting up before the meeting and tidy up after it!
  Discussions about the group organisations have been continued since the last presentation at the LCU meeting. This topic has been discussed also at a retreat between SLs and GL yesterday. The reviewed mandate (following feedback by JJ and SF) is presented: this includes the proposals by JJ and some revisions. The section will be responsible for the various circular machines of CERN. In particular, the LHC optics database will be under the responsibility of RDM, while the database of the other machines and transfer lines will be under the responsibility of Olav Berrig.
  As far as the time line of the re-organisation is concerned, two scenarios are being considered: do it now, or by the end of the year, matching the change of Director of Accelerators. More news will be given by Oliver at the group meeting.
• Collimation status -> RB
  The main focus of the whole team is the review that is being organised. The details can be found here.
• MAD-X status -> LD
  No more memory leaks! This key improvement justifies a release of a pro version.
  The space charge development by FS (frozen distribution) is now available in the development version. Documentation has been promised too.
  A bug in the TILT for dipoles has been fixed.
  It is reminded that the generic address mad@cern.ch should be used to communicate with the people in charge of the code.
  MG reminds to keep LD informed of any possible issue about MAD-X such that he can follow up the situation.

LHCb crossing scheme for Run II & III -> SF (slides)

SF discussed a proposal of keeping the crossing angle in the horizontal plane for IR8 at injection. Even if the nominal conditions (170 murad and 2 mm parallel separation) are not enough to ensure always a sufficient beam-beam separation, the increase of the parallel separation provides (up to 3.5 mm) provides the missing bit. This solution is particularly interesting as it guarantees the correct beam-beam separation also for the case of p-Pb runs, when the beam-beam encounters at injection are moving over time. An additional optimisation can be performed by adding a small angle in the plane of the parallel separation so to bring the value of n1 (using nominal values for beam parameters and tolerances) to 6.5 sigma, hence within specification.
At top energy the option of tilting the crossing plane will be still available and the choice will be left to the physicists to apply it or not.
The outcome of this study is that there is no more need to envisage a rotation of the beam screens for the triplets in IR8.
Given the positive feedback during the meeting, two presentations could be planned at the forthcoming LMC: one by SF on the proposed scheme at injection and during ramp, and one by BH to review the aperture measurements and the proposed gymnastics to perform the change of crossing plane prior to collisions. At the next meeting the such a gymnastics will be reviewed.
During the discussion, the issue of measured beam parameters for 25 ns beams has been raised: the report about the recent measurements can be found here.

AOB 

Last update: 21-May-2013

MG & HB

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