Minutes of the ICE section
83rd meeting on Wednesday 05/06/2013 (08:40-10:30, 6/2-004)
ICE members: Adrian Oeftiger (AO), Benoit Salvant (BS), Carlo Zannini (CZ), Danilo Banfi (DB), Daria Astapovych (DA), Elias Metral (EM), Elena Wildner (EW), Frank Schmidt (FS), Giovanni Iadarola (GI), Giovanni Rumolo (GR), Javier Barranco (JB), Jean-Luc Nougaret (JLN), Kevin Shing Bruce Li (KL), Nicolo Biancacci (NB), Nicolas Mounet (NM), Olav Ejner Berrig (OB), Serena Persichelli (SP), Sergio Rioja Fuentelsaz (SRF), Tatiana Pieloni (TP), Werner Herr (WH), Xavier Buffat (XB).
Present/Excused: BS, CZ, DB, DA, EM, EW, FS, GI, GR, JB, JLN, KL, NB, NM, OB, SP, SRF, TP, WH, XB, Guido Sterbini, Witold Kozanecki (from ATLAS).
1) Newcomers / visitors
- Adrian Oeftiger on 03/06/2013: PHD student with Giovanni Rumolo to work on space charge (3D effects) with the space charge team.
2) Comments on the minutes of the previous 82nd meeting + Actions
- No comment.
3) General infos
- No particular comment from anyone.
- SL meeting:
- I was not there last week.
- Thanks for the proposals to help for the ABP BBQ on 19/06.
- Discussion about the follow-up to be made for the LHC instrumentation (MIM etc.). Ongoing.
- Follow-up of IR8 and email from MassimoG about IR8 crossing scheme at injection: StephaneF presented a proposal for a reviewed crossing scheme in IR8 at injection (http://ab-dep-abp.web.cern.ch/ab-dep-abp/LCU/LCU_meetings/2013/20130522/lhcb2.pdf). The resulting minimum beam-beam separation is >= 10 sigma.
=> Is it OK for / approved by the beam-beam team? WH mentioned that this item is followed up by BernhardH and beam-beam team. EM mentioned that (he thinks) there are 2 studies in parallel, one by BH and one by SF and that both will report to the LMC at some point => Therefore, the beam-beam team should comment on the 2 proposals. Action 1: Beam-beam team.
- Discussions about our possible new name and mandate.
- Discussion about possible studies at ASTA (1st Advanced Superconducting Test Accelerator (ASTA) User's meeting, Fermilab on 23-24/07):
- FS will attend and the idea is to propose to test the circular modes there before implementing it at CERN.
- Any other idea? Please send any other idea to FS.
- Non conformity => IC-QQBI.29R5_5contactstripsProtrudingIntoAperture.png. Should we do something? Action 2: impedance team. MassimoG is looking into the possible aperture pb.
- Important events last week?
- SC seminar (summary of the SC2013 workshop by FS) and SC meeting.
- Collimation review => Talk by NM.
- ElenaS's 2nd on High Harmonic RF system review for HL-LHC.
- LHC scrubbing meeting the week before (GR).
- Some RF meas. on ALFA by OlavB and JosephK => To be discussed at some next impedance meeting.
- Reminder: Every 2 weeks we will have a brief report about the activities/status/issues in the different working groups => Start next week.
- TOTEM collaboration week -> Tuesday 11.6. from 10:00 to 12:30 upgrade session => EM has been invited to give a presentation (~ 20 minutes) related to LHC RF in general and evaluation of the proposed insertion of the (RF optimized) Roman Pots at low beta * / high luminosity.
- Finalization of the LHC performance review:
- Place: 6-2-004. Should be possible to have 40 people. We could add few chairs and remove some tables if needed...
- Dates reserved: 25/09/2013 (from 09:00 to 13:00) and 26/09/2013 (from 09:00 to 17:30) => We will see what we will finally use.
- Proposition made here with all the questions which seem to be on the table (and therefore which we need to try and address) and possible contributors etc. => But, the detailed plan to attack all these questions and presentations should/will be discussed in the team (to try and optimize the effort) and we will finalize all this by the end of this week.
4) Beam-beam deflection during the Van der Meer scans (TP): pptx
- Beam-beam impacts on VdM scans?
- Possible typo: seems the Moller Kinematic Luminosity Factor is missing in the general formula of the luminosity. The equation below is correct.
- vis in the slides means visible.
- Usual beam conditions: no crossing angle and imilar to single bunches (i.e. no BBLR) but with effect or not of other IPs.
- Gaussian fit of Lumi scans to extrapolate muvisMax and CapSigmax or CapSigmay.
- Meas. made in the past in LEP of the orbit along the machine vs. transverse beam offset to deduce the beam-beam kick => See SL Note 96-01 (OP).
- On slide 6:
- CapSigma12 allows for some linear coupling but it is very small in the LHC and put to 0.
- CapSigmax or y =Sqrt[CapSigma11 or 22 depending on the plane].
- WitoldZ mentioned that the beam-beam effect is twice as big as the dynamic beta effect and it happens to be in the same direction => It has to be correctly taken into account. The consequences for the 2011 and 2012 results are under study.
- BB team provided WitoldZ a Python routine to be implemented in the luminosity calculations to calculate the BB orbit effect for given beam parameters:
- BBScan.py: to test the BB routine, available for estimates.
- BB.py: calculation routine uses Bassetti-Erskine general formula and computes kicks and orbit effects.
- BassErsk: to calculate the electric fields Ref. CERN-ISR-TH/80-06.
- Comparison between self-consistent and non-self consistent treatments confirms order of magnitude but the real effect has to take into account both beams => TRAIN code needed. Ongoing work as TRAIN code is now running again but the format of the MAD files changed and this is has to be updated in the TRAIN code.
5) Actions to be taken for the next meeting
- Old actions.
- New actions:
- Action 1 (Beam-beam team): Is a minimum separation of 10 sigmas OK / enough for the new IR8 crossing schemes at injection?
- Action 2 (Impedance team): Is the NC http://emetral.web.cern.ch/emetral/ICEsection/2013/2013-06-05/NC_IC-QQBI.29R5_5contactstripsProtrudingIntoAperture.png a pb and should we propose to repair it?
6) Miscellaneous
- Deadlines and important dates for ICE.
- The next (84th) meeting will take place on 12/06/2013 => Agenda:
1) Simulations of the longitudinal coupled-bunch instability in the PS (Mauro Migliorati).
2) Brief reports of the 4 WGs (by the WG leader or replacement) => Plan, activities, deadlines, issues, etc.: BB, SC, EC, IMP.
- See preliminary agendas for the next meetings.
- See List of Actions.
Minutes by E. Metral, 05/06/2013.
