Minutes of the ICE section

16th meeting on Wednesday 09/02/2011 (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).

Present/Excused: BS, CH, CZ, HD, EB, EHM, EM, EW, FS, GR, JLN, KL, MCAP, NB, NM, OB, TP, WH, Emanuele Laface, Eirini Koukovini Platia, Gersende Prior, Hannes Bartosik, John Jowett, Mathilde Favier, Octavio Dominguez Sanchez de la Blanca, Rama Calaga, Riccardo de Maria, Vittorio Vaccaro.

1) Newcomers / visitors

- Vittorio Vaccaro for 6 months (started on February 1st).

- Yuri Alexahin for 2 weeks (from 04/02 to 20/02) to work on beam-beam with Frank Schmidt (to take part in the project "Resonance and coherent beam-beam analysis for LHC") => Will give a talk on beam-beam at the next week ICE meeting + seminar on Muon colliders.

- Other visitors who should come soon, with FrankZ (for e-cloud):

- Kazuhito Ohmi: 23/2 to 8/3.

- Giuliano Franchetti: 14/2 to 8/3.

- Ubaldo Iriso: 7/3 to 8/3.

2) Comments on the minutes of the 15th meeting + Actions

- No comments.

- List of Actions => We will look at it on some detail at one of the next meetings.

3) General infos

- No particular comment from anyone.

- CAS participation from ICE people in 2011 (in addition to WH who will go to both as lecturer and/or organizer, and it will be paid directly by the CAS):

- Summer student requests => 2 from ICE:

- 1 for CH on beta-beams.

- 1 for OB on PS accelerator apertures.

- Any conferences/workshops ideas yet?

- SL meeting last week:

- The budget for students is extremely tight. It will be really hard to get more students than what we have now.

- EPFL students: they should always fill the travel authorization and EDH for any professional trip (even for meeting with the EPFL supervisor).

- The CERN-LARP meeting was held on 04/02/11.

- MAC recommendations after Chamonix2011:

- Scrubbing with 50 ns asap.

- Continue with 50 ns for physics and step back to 75 ns only if strictly needed.

- Agreed with the proposal to delay the first long shut down.

- Encouraged CERN to prepare a resource load long-term planning.

- Encouraged CERN to organize a review for the interconnects and proceed with the thermal amplifier.

- Encouraged CERN to stay at 3.5 TeV this year.

- Encouraged CERN to optimize the performance of the injectors for 50 ns and 75 ns.

- Encouraged CERN to pursue the wire beam-beam compensation in the framework of the HL-LHC project.

- Encouraged CERN to pursue the analysis of the batch compression scheme, while were not particularly supportive for the RCS option.

- 1st LHCBOC (LBOC) meeting yesterday, with Tatiana as scientific secretary. GianluigiA will be co-chairman with or deputy chairman of JorgW.

- BS will replace SimoneG as scientific secretary of the FOM.

- Talk on beam cooling: past, present and future by D. Mohl => Will finally not be possible as Dieter would have to redo all his transparencies... We then have to read carefully one of his latest paper: http://cdsweb.cern.ch/record/504627/files/ps-2001-021.pdf.

- Ecloud workshop at CERN on 07-08/03/2011 organized by GR => http://indico.cern.ch/conferenceDisplay.py?confId=125315.

- Today, after the 1st talk on flat beams in SIXTRACK, we will review the different equipments we used last year during ecloud MDs. Concerning the latter subject:

- I will start to write an MD note in the next few weeks => Please send me a contribution linked to each equipment (Action: All the people responsible for an instrument, see list below in point 5)).

- JorgW is looking for some help to test the LHC applics next week => Riccardo de Maria, BS, NM, TP, CH and Hannes Bartosik will help (many thanks in advance!).

4)  Flat beams in SIXTRACK (Emanuele Laface): pdf

- Reminder:

- In SIXTRACK, the beam-beam implemented is the weak-strong, where a single particle feeling the beam-beam force from Beam2 is tracked.

- The electrical field formula of a 2-dimensional Gaussian charge from Bassetti-Erskine is already implemented in SIXTRACK. BUT, but SIXTRACK does not calculate the optics for Beam2 (actually Beam2 does not exist for SIXTRACK) => The positions and the sigmas of the bunches of the Beam2 must be provided in some way. 

- Up to now, the positions were passed from MadX and the sigmas were calculated from the Beam1, guessing that the optics is symmetric or anti-symmetric => This cannot work for flat beams (the optics is not anti-symmetric) => Solution from Emanuele: He passes the sigmas of Beam2 from MadX. Note that in case of "strong" linear coupling this approach might not be sufficient, but for the LHC and LHC upgrade the approximation should be fine, as linear coupling should be small.

- In practice, what is new:

- When the sixtrack command is invoked in MadX, the fc.2 proposes now 3 additional columns: σx, σy and σs (not used).

- To read these 3 additional columns in SIXTRACK, the flag lhc, in the section BEAM of the fort.3 file, must be set equal to 2. (lhc=0 is for symmetric optics, lhc=1 is for anti-symmetric optics and lhc=2 is for read from file).

- Some first tests were performed and it seems that everything works correctly but this new option still needs to be studied in detail.

5) Review of LHC equipments which we used during our ecloud MDs in the LHC in Oct/Nov 2010 (how many equipments? how do they work? Different modes of operation? Data saving? etc.):

- Transverse dampers (Riccardo de Maria): pdf.

- HeadTail monitor (Benoit Salvant): ppt.

- LHC BPM (Nicolas Mounet): pdf.

- Schottky monitor (Tatiana Pieloni): pdf.

- Transverse emittance measurements from BSRT (Christian Hansen): pdf.

- Transverse emittance measurements from FWS (Carlo Zannini): ppt.

- BCT and FBCT (Gersende Prior): pdf.

- BLM (Humberto Maury Cuna and Octavio Dominguez Sanchez de la Blanca): Next week.

- BBQ (Tatiana Pieloni and Benoit Salvant): Next week.

- John Jowett mentioned also the BGI in the LHC, which we did not use during our studies, but which he looked at in particular to install them in the MAD layout => BI optics and layout link: http://jowett.web.cern.ch/jowett/LHC-BI-optics/BIoptics.html. John made it during the ion run in order to install the BGI monitors in the MAD layout (they are still not present ) but it also shows information about all the BI in LSS4. It is actually valid for all optics since this insertion never changes (the optics shown is the ideal optics, not measured, of course).

6) Actions to be taken for the next meeting

- Old actions.

- New actions:

- Action 1: All people responsible of a LHC equipment during ecloud MDs in the LHC in 2010 => Send to EM a contribution for a MD note by the end of March. EM to publish then the MD note.

7)  Miscellaneous

- The next (17th) meeting will take place on 16/02/2011 => Agenda:

1) Experience with beam-beam effect at the Tevatron by Yuri Alexahin.

2) LHC BLM by Humberto Maury Cuna and Octavio Dominguez Sanchez de la Blanca.

3) LHC BBQ by Tatiana Pieloni and Benoit Salvant.

- See preliminary agendas for the next meetings.

Minutes by E. Metral, 13/02/2011.