Summary notes of the LCU meeting on 11/12/2012

Present: FB, RB, HB, RDM, LD, MG, PH, BH, JJ, EM, MS, RT, AV, RV

Report from meetings

• SLM and general information -> MG
  Approval and submission of IPAC'13 abstracts is done. The whole procedure has been discussed and the feedback gather during the LCU meetign has been transmitted by MG to Oliver and the other SLs.
  A faulty corrector in IP8 at Q5 will be replaced in LS1. The warm corrector that has been installed will be removed. The as built LHC sequence will be updated accordingly.
  MG is following up on positioning of dipole magnets which will be replaced in LS1 in the context of magnet splice repairs.
  Several of use were involved in the recent LHC MDs. RT said they could verify with optics measurements, that calibration errors of roughly one per cent on MQY magnets in IR8 are now corrected. Reports on all recent MDs will be given in a forthcoming LSWG meeting.
  The end of year christmas BE-ABP party is schedule for this Thursday afternoon.
  We were informed by FZ about 3 EuCARD-AccNet events in early 2013 :
  
  10 January, EuCARD TLEP3 Day
  19 February, EuCARD SAPPHiRE Day on laser, cavities & FELs for a gamma-gamma Higgs factory.
  21 February, EuCARD (V)HE-LHC Day, jointly with US Snowmass high-energy hadron colliders preparatory group
  
  HB introduced Frederic Bouly, who joined our group this month to work on the collider-experiment interface (HL-LHC WP8).

• Collider-Experiment Interface Workshop -> HB
  The one day workshop was organized on the 30 November in the context of work package 8 for the HL-LHC.
  The requests for layout changes required by the 4 large experiments and forward detectors were presented in the first part of the workshop. The second part had presentations of the machine aspects including several speakers from our group. All talks are on indico.
  An essential part of the workshop were the discussions between the talks and at the end of the workshop to identify the most critical aspects and prepare for follow up. Executive minutes are in preparation.
• MAD-X status -> LD
  Laurent is finalizing the latest development release, which should be the latest before a new production version.
  A major revision of MAD-X, including also the core, will be launched in the near future. Bugs and request are tracked and followed up.
  MG mentioned that we are working on the (re) implementation of tracking of thick quadrupoles.
  HB works on an upgrade of makethin and the selection mechanism for makethin to implement slicing to thick quadrupole slices.
  RdM works on interpolation functions for parameter which should help to get smooth transitions between optics as required for the beta-squeeze.

Considerations on IR8 vertical crossing at injection -> BH (slides)

BH reported on the current status of work on the beam crossing scheme for LHCb for operation after LS1. The LHCb requires regular polarity changes on their spectrometer, which flips the sign of the internal horizontal crossing angle. A combination of internal and external crossing angles and parallel separation is required to avoid parasitic collisions.

The amount of horizontal external angle required depends on the polarity. For one polarity, we profit from the natural ring geometry of the LHC. The other polarity is much more problematic.
Partial parallel separation is also used in physics for luminosity leveling.
The current crossing scheme is not compatible with 25 ns operation at injection.
BH discusses to flip the planes for the external bumps, going to vertical external crossing angle and parallel horizontal separation, which would make the polarity change much more transparent.
The vertical crossing angle size will be limited to about +/- 108 mural by aperture in the beam screen, which was oriented for the horizontal crossing angle. The beam-beam separation would 10 sigma (for an emittance of 3 mum). This may be compatible with somewhat optimistic emittance and tolerance estimates.
The rotation of the beam screen which could earliest be done in LS2 could then be avoided.

AOB

None

Last update: 12-December-2012

MG & HB

Back to LCU Minutes