Minutes of the ICE section
99th meeting on Wednesday 18/12/2013 (08:40-10:30, 6/2-004)
ICE members: Adrian Oeftiger (AO), Andrea Passarelli (AP), 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), Kevin Shing Bruce Li (KL), Nicolo Biancacci (NB), Nicolas Mounet (NM), Olav Ejner Berrig (OB), Serena Persichelli (SP), Tatiana Pieloni (TP), Xavier Buffat (XB).
Present/Excused: AO, AP, BS, CZ, DB, DA, EM, EW, FS, GI, GR, JB, KL, NB, NM, OB, SP, TP, XB, AndreaP, VincenzoF, HannesB, MichaelB, ChristineV.
1) Newcomers / visitors
- None.
2) Comments on the minutes of the previous 98th meeting + Actions
- Minutes not yet available.
3) General infos
- No particular comment from anyone.
- SL meeting:
- GianluigiA and JanU have been nominated as the future LHC MD coordinators.
- Next TSC => Send requests to DR on 14/01/2014 mid-day.
- Talk from Hannes at SPSU on SPS TMCI => Many nice results.
- Colloquium by SteveM last Friday.
- Ecloud meeting on Monday.
4) LHC single-bunch instabilities observed in 2012: simulations vs. measurements (DA): pdf
- DA reviewed the motivation for these studies and discussed in some detail the instability observed on 02/04/2012 during the collimator's loss maps (fill #2447):
- 2 bunches / beam, ADT switched off, at the end of the squeeze, focusing octupole current Ioct= -400 A.
- 1st instability on Beam1, H plane, rise time of ~ 3 s.
- 1st instability on Beam2, V plane, rise time of ~ 23 s.
- Large uncertainty on emittances and chromaticities.
- HEADTAIL simulations:
- Convergence study done => # of slices and # of macroparticles for reliable simulations.
- Case of the B1H instability:
- Rise time ~ 10 s for Ioctupole = 0 A and stability for - 50 A. Chroma ~ + 0.8.
- In the case of negative chromaticity (- 3.9), the beam is unstable even at Ioctupole = - 600 A.
- Plan for the future: Find from HEADTAIL the intensity, at which the observed instability can be reproduced with the same rise time with Ioctupole = - 400 A.
5) Special afternoon meeting with Joel Chaskalovic to discuss "Theoretical and Numerical Approaches for Vlasov-Maxwell Equations" and data mining
- After our ICE section Christmas lunch at the cafe de Peney (see pictures), the afternoon was devoted to discussions about the "Theoretical and Numerical Approaches for Vlasov-Maxwell Equations" and data mining with Joel Chaskalovic (French Associate Professor in Mathematical Modeling applied to Engineering Sciences, University Pierre & Marie Curie, Paris).
- Joel made a detailed presentation of what they did and what could be useful for them => Slides.
- Then, FS gave a short introduction about our space charge studies (slides), NM about our instabilities studies (slides), TP about our beam-beam studies (slides) and finally GR about our ecloud studies (slides).
- Conclusions:
- Joel should discuss with Alessandra Lombardi (studying the beam dynamics of the particles at the lowest energies at CERN), as what they did until now concerns "only" the “Auto champs”, i.e. the case where all the other fields can be neglected => Will she have interesting data where they can check their model?
- Joel needs to improve their model if they want to apply it to our (real) cases (with other, external, fields). Furthermore, the question of the observables we have would remain…: do we have enough of them?
- Proposition from MassimoG to apply their data-mining approach to all the data stored in Timber.
- Other conclusions/ ideas?
6) Actions to be taken for the next meeting
- Old actions.
7) Miscellaneous
- Deadlines and important dates for ICE.
- See List of Actions.
- Today is the last ICE meeting as next year the ICE section will be replaced by the HSC section! => Many thanks to all the participants to these meetings for the very interesting discussions we had!
Minutes by E. Metral, 11/01/2014.
