Summary notes of the LCU meeting on Friday 14/06/2013

Present: RA, FB, HB, LD, SF, MF, MG, BH, AL, EM, SR, GR, RT, RV, PS

Report from meetings

• SLM and general information -> MG
  Massimo commented on the B2 field component of the LHC dipoles. So far it is not used by default in our LHC strength files. Including the known B2 component together with the MQTs used for compensation as baseline would bring us closer to the real machine. Rogelio said he would be in favor and it would reduce the corrections needed. The corrections depend on energy and would require a rematch of our nominal strength files. Stephane said he would prefer to not change the default and take care of this by an extra script. To be further followed up by Massimo, Rogelio and Andy with a proposal in one of our next meetings.
  The crossing angle in LHCb will be discussed in the next LMC.
  The section mandate shown last time was adopted. The changes to our group structure will be presented in the ABP group meeting next week.
  Bernard Holzer said he attended a very interesting 1st European Advanced Accelerator Concepts Workshop in the first week of June.
• Collimation status -> TBC
  Stefano said the collimation team is in the process to digest the outcome of the recent collimation review which was a major milestone for the collimation project. He has not yet received the full report from the reviewers. A short version was already made available directly after the review meeting. The review strongly supports the work for the 11T option for dispersion suppressor (DS) collimation. It is planned to first equip IR2 with DS collimators to match the requested luminosity increase by ALICE for PbPb collisions. Next would be IR7, to be confirmed by quench limit measurements at top energy after LS1. DS collimators in IP1 and IP5 may be added for ATLAS and CMS to allow for higher PbPb luminosities and would also be useful for protons for the HL-LHC. The review committee was also supportive for the continuation of material studies. Stefano plans to present a report on the collimation plans in the LMC, after reception of the final review report.
  Stefano said that a half day mini working group meeting will be organised soon on the collimation module in SixTrack. One extension discussed is the implementation of hollow lenses collimation.

• LBS -> HB
  Helmut said, that a major item in the last meeting in May was the CMS upgrade plans for background detection, which require an improved time resolution for 25 ns operation after LS1. The next meeting on Monday 17 June will include reports on background observations with very tight collimation at high-beta* and a comparison of 25 and 50 ns backgrounds, see  indico.

Tilting the crossing plane at top energy -> BH (slides)

Bernhard gave a presentation in preparation of the discussions planned for the next LMC. The main difficulty is related to the LHCb spectrometer bump polarity changes. The implementation of the tilted crossing scheme in 2012 was done with the help of Reyes and Reine. LHCb saw systematic effects depending on the spectrometer polarity in 2011. The 2012 data is still being analyzed. For the moment it is assumed that spectrometer polarity changes will also be requested after LS1.
A complete scheme has been studied and will be presented at the LMC: the smaller physical emittance due to the higher energy will help and make the gymnastic easier than at 4 TeV. This option will be made available to LHCb, which will have the possibility to use it in operation in case the on-going studies show a real need for this complication.

AOB 

It is planned to schedule the next meeting at the standard day and time, Tuesday morning at 10:00, in the second week of July.

Last update: 25-June-2013

MG & HB

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