Minutes of the ICE section
31st meeting on Wednesday 08/06/2011 (08:40-10:30, 6/2-004)
ICE members: Benoit Salvant (BS), Christian Hansen (CH), Carlo Zannini (CZ), Hugo Alistair Day (HD), Elena Benedetto (EB), Ewen Hamish Maclean (EHM), Elias Metral (EM), Elena Wildner (EW), Frank Schmidt (FS), Giovanni Rumolo (GR), Jean-Luc Nougaret (JLN), Kevin Shing Bruce Li (KL), Maria Carmen Alabau Pons (MCAP), Nicolo Biancacci (NB), Nicolas Mounet (NM), Olav Ejner Berrig (OB), Tatiana Pieloni (TP), Werner Herr (WH), Xavier Buffat (XB).
Present/Excused: BS, CH, CZ, HD, EB, EHM, EM, EW, FS, GR, JLN, KL, MCAP, NB, NM, OB, TP, WH, XB, Alexey Burov, Frank Zimmermann, Fritz Caspers, Georges Trad, Hannes Bartosik, Humberto Maury Cuna, Raymond Wasef, Tatiana Libera Rijoff, Vittorio Vaccaro.
1) Newcomers / visitors
- Alexey Burov arrived on June 1st and will stay for 1 year.He is in the office of Chandra and Humberto (6-2-002):
- Alexey will in particular help us in (1) computing the impedance of the 3 SPS MKDH laminated kickers, which are horizontal kickers used to dump the beam below ~ 37 GeV/c; (2) understanding better the effect of space charge of the different instabilities observed at CERN (PSB, PS, SPS and LHC); (3) studying the interplay between the SPS transverse impedances (dipolar and quadrupolar) and the ecloud on the observed TMCI-like vertical instability in the SPS with the nominal LHC beam when the chromaticity is corrected.
- Alexey recently benchmarked his new theory of longitudinal bunch stability against some measurements in the Tevatron => He could/will present these results at one of the next ICE meetings.
- Furthermore, Alexey could also give at some point (~ end of the summer) a more philosophical talk: Proofs and refutations of god's existence.
2) Comments on the minutes of the previous 30th meeting + Actions
- Comment from Rogelio => EM mentioned that Sussix corrects for the phase but this is not true (as shown by NB) => Sussix needs both amplitude and phase correction (EM mentioned only the amplitude correction needed). EM corrected the previous minutes.
3) General infos
- No particular comment from anyone.
- EM will add Tatiana Libera Rijoff (working with FrankZ on BBLR compensation) in the emailing list.
- SL meeting (on Monday):
- Reminder for HD, EHM and XB who got a grant to attend IPAC2011 => Try and reserve the flights asap to benefit from the cheapest prices.
- USLARP: OliverB sent the 2 proposals for SLAC collaboration on collective effects (to Yunhai Cai):
- Impedance calculations for the new injection hardware to be installed in the PSB as part of the LINAC4 to PSB injection,
- Electron cloud build-up simulations for the PS with 25 and 50 ns beams with bunch intensities beyond 2E11 p/b as part of the studies for the PS upgrade.
- Hans Grote will (definitively) stop at the end of the year to work on MAD.
- News on the LHC:
- 08:30 meeting on Monday:
- Production in the previous week ~ 200 pb^-1 => 700 pb^-1 in total already reached!
- Highest lumi per fill = 46.5 pb^-1.
- 144b injection => Fully commissioned & tested, but not used yet.
- LSWG yesterday:
- Mini Chamonix after the 2nd MD block => Tentative date = 15/07 (seems to be already fixed).
- MD slot reserved to study the transverse emittance BU at injection => Tentative planning: Thursday 30/06 from 00:00 to 09:00 => I still have to fill a form. We need to understand the origin:
- Is it linked to the impedance or not? (chroma etc.)
- Is it linked to the magnetic history? This is not yet proven. In particular, on 01/06 there were at least 3 consecutive fills (in fact more) where we accelerated to 3.5 TeV and where no transverse emittance BU was observed: Some other LHC fills with and without TEBU at injection (EM)).
- Can we reproduce the observed transverse emittance BU etc.?
- We could try and play with chrom, octupoles but also RF voltage (as suggested by Karel) => Reducing it to increase the Landau damping (what about then capture losses)?
- We should also try and disentangle between transient effects at injection and the stationary situation after all the batches injected.
- NM => Stability diagrams from octupoles for Landau damping with a Gaussian distribution: I made an error in the plot for one part of the curve => Was corrected by NM and RaymondW is studying these distributions in detail, comparing them to HEADTAIL's results => He could/will present all this at some point.
- Discussion with Werner Herr => After the working groups' review, we will make each time a short round table for the different working groups in case there is some interesting things to report.
- BB experiments in Tevatron (FS) => Shifted by one week to the 16th of August.
- Link to the 2011 LHC collimation review at CERN on June 14-15: https://indico.cern.ch/conferenceDisplay.py?confId=139719. NM will give a 15-min talk "Impedance without IR3 upgrade", where he should discuss: Impedance from tight collimation settings as achieved in MD. Will the beams be stable with impedance, taking into account stabilization from transverse damper and octupoles?
- News about impedance measurements of the PS WS? HD mentioned that all the measurements have been done and the results are being currently analysed.
- FS mentioned that there is currently a lot of activities about the LHC nonlinear chromaticity: studies + MDs.
- BS briefly showed (due to time constraint) his recent studies on impedance effects of a composite beam pipe for the experimental areas. Several discussions arose on the effect of NEG, which was studied in detail in the past and whose main conclusions should be reviewed.
4) Main activities and news from the Ecloud WG (FZ): pptx
- ?.
5) Main activities and news from the Beta-Beams WG (EW): pptx
- ?.
6) Actions to be taken for the next meeting
- Old actions.
- New actions: ?.
7) Miscellaneous
- The next (32th) meeting will take place on 15/06/2011 => Agenda:
1) End of the review of the main activities and news from the Beta-Beams WG (EW),
2) Main activities and news from the Beam-Beam WG (WH),
3) Main activities and news from the Space Charge WG (FS).
- See preliminary agendas for the next meetings.
Minutes by E. Metral, ??/??/201?.