Summary notes of the joint ICE/LCU meeting on 24/01/2012

Present: HB, RC RdM, LD, OD, SF, MF, MG, WH, BH, LL, EM, EM, BS, FS, MS, MSt, RT, FZ, AL, JB

Discussion about the Large Piwinski Angle MD -> FZ (slides)

The LCU meeting started with a presentation targeted to both the ICE and LCU sections. Studies with a large Piwinski (crossing) angle are relevant for the LHC upgrade. The beam size is effectively increased and the luminosity decreased with the inverse of the Piwinski angle.

This was first analyzed by Anton Piwinski working on DORIS at DESY. The subject was also shortly studied in the SppbarS collider by Werner Herr et al.  Werner said, that the mechanism is to some extend similar to beam-beam dynamics with offset collisions.
FZ said that little is known about the beam-beam limit for hadron colliders in presence of a large Piwinski angle, so that this study would be very important to guide LHC upgrade options. The study would be done at injection energy in the LHC, where a large Piwinski angle can be produced by ramping down the internal crossing angle. It will be important to distinguish between emittance growth which would be mainly caused by particles at small amplitude and potential lifetime problems caused by increased large amplitude halo particles.

Report from meetings

• SLM and general information -> MG
  Construction and renovation work is ongoing at buildings 6 and 9, and may cause inconveniences like noise and reduced parking space.
  An email was circulating asking for travel plans this year to help with the travel budget planning.
  ALICE and LHCb presented their plans for smaller beam pipes in the LEB meeting on Monday. While ATLAS/CMS already asked for modified beam pipes in LSS1, the time scale for IP2/8 would be later with implementation in LSS2, keeping the modified beam-pipes for the HL-LHC.
  MG reminded that HR introduced the competence model and that competencies, both technical and in behaviour are included in this years MARS.
• LMC -> FZ
  We had the 1st LMC in 2012 discussing the shutdown work including the vacuum intervention at CMS and a short summary of the Evian workshop. For more details see the LMC minutes.
• LBS -> HB
  The LBS#32 meeting on Monday  discussed the vacuum related shutdown work, shielding simulations for ALICE and exchange of off-line data between experiments and the LHC.

MAD-X status -> LD
Laurent gave an update of the status of MAD-X. He made a new set of web pages, which can be reached with as http://cern.ch/mad . The web pages also explains the road map which proceeds in 3 phases. We are currently in phase 1 where all changes should be transparent to the user.

Ideas for implementing RF-multipoles in MAD-X (and transferring them to SixTrack) -> AL (slides)
Andrea Latina reported about the implementation plans for rf-multipoles in MAD-X, which would also allow for a simulation of dynamic higher order effects introduced by crab cavities.
He recalled the standard multipole expansion use for static quadrupoles, and how this can be generalized for rf-multipoles.
Two steps are foreseen for the implementation :  adding a new thin element RFMULTIPOLE and modification of EFCOMP to allow to attach rf-multipole errors to magnets.
The implementation will also require changes in several modules in MAD-X including TWISS, TRACKING and MAKETHIN.
It remains to be seen if the extra element CRABCAVITY will be kept and converted into RFMULTIPOLE or removed.

AOB

High-beta* and crossing angle -> HB (slides)
Following a request from people in ALICE, HB looked into the compatibility of a crossing angle and high-beta* operation. There is potential for intermediate beta*  of 30 m  to 100 m operation in ALICE in parallel with low-beta* high luminosity operation in the other experiments. This might open new windows to study diffractive physics and allow to measure small diffractive cross sections which require extensive running time at intermediate beta*.

Last update: 27-January-2012

MG & HB

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