Minutes of the ICE section
94th meeting on Wednesday 23/10/2013 (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), Sergio Rioja Fuentelsaz (SRF), Tatiana Pieloni (TP), Werner Herr (WH), Xavier Buffat (XB).
Present/Excused: AO, AP, BS, CZ, DB, DA, EM, EW, FS, GI, GR, JB, KL, NB, NM, OB, SP, SRF, TP, WH, Johannes Herbst, GuidoS, HannesB, AndreaP, SimonW, AlexejG, ElenaB, RaymondW, FritzC.
1) Newcomers / visitors
- Simon Hirlander (working with MassimoG in particular on the LHC tunes at injection vs. intensity) will be added to the list of ICE distribution.
- Johannes Herbst started with the impedance team several weeks ago already and is around for another 3 weeks => Working with OlavB on impedance measurements.
2) Comments on the minutes of the previous 93rd meeting + Actions
- No comment.
3) General infos
- No particular comment from anyone.
- SL meeting:
- FCC (Future Circular Collider) kick off meeting already took place. Michael Benedikt is contacting some people and organising the project.
- There was a CST course (2-day introduction + 1-day advanced with many people from the impedance team) => Was quite interesting and useful.
- Concerning the 2 workshops (Darmstadt on 2-4/12/13 and SOLEIL on 16-17/01/14) => Who has a talk? Who would like to go? To try and prepare for it.
- Very nice talk from SimonW (and NicolasM) at the TLEP workshop => Nice pictures of synchro-betatron resonances => Should be disucssed also at some point here for info or at least all, please have a look.
- IPAC14 participation discussed.
- Hermann Schmikler will replace RalphS as project leader for the Beam Beam Long Range Compensator.
- WP2 => Talk from BS and GI last week. This Friday, talk by EM on impedance and beam stability (work from NM).
- Impedance 2014 => Discussion with people from impedance team and current plan is to have it in Erice on 23-29 April 2014.
- Issue with a MKI kicker with 1 RF finger not touching => Many studies performed and decision taken on TU 22/10/013:
Non-conforming RF finger in MKI12-T12: MKI12-T12 will be installed, as planned, in W45. It may be possible to exchange a not so good MKI magnet prior to the end of LS1 if the remainder of the MKI program proceeds smoothly – otherwise, if required, the MKI could be exchanged for a spare during a TS
=> Suggestion to be discussed also at the LBOC.
- Very nice results from AlexanderH on comparison between meas and HEADTAIL simulations for the PS oscillations at injection => More detail this afternoon at the PS LIU meeting.
4) RF quadrupole for Landau damping (Alexej Grudiev): pptx
- AG first reviewed in some detail the paper from Berg-Ruggiero1997 on " Stability diagrams for Landau damping" => Transverse coherent instabilities can be stabilised by betatron and synchrotron tune spreads coming from transverse and longitudinal plane.
- Currently, in the LHC we are relying on the transverse tune spread created by the Landau octupoles, but
- Landau octupoles were at their max current in 2012 and we still had some instabilities.
- Increasing the energy will make them less effective. Note that the ATS optics would help in this respect due to the larger beta functions at the octupoles.
=> AG's idea: can we use an RF quadrupole to provide the required transverse Landau damping?
- Note that AlexeyB wanted also to try and profit from the longitudinal to transverse Landau damping => http://emetral.web.cern.ch/emetral/ICEsection/2012/2012-10-24/Long_Trans_Stab_Diags.pdf.
- AG explained then in detail what an RF quafrupole is and does
- Synchrotron frequency in the presence of an RF quadrupole derived.
1) Longitudinal spread of both H and V betatron tunes is non-zero for and RF quad
2) Both H and V transverse spreads of synchrotron tune are non-zero for and RF quad => But 1) is much more efficient than 2) for the LHC 7 TeV parameters.
- AG made then a 1st estimate of the required strength of the RF quad in IR4 to damp a mode with a coherent tune shift of ~ 2E-4 at 7 teV and a first design of a 800 MHz Pillbox cavity RF quad => 3 cavities would be enough (1 m long section required).
- AG finally proposed that maybe some tests could be done in the SPS with 1 cavity prototype.
=> In summary, very nice idea and proposition from AG which needs to be studied in detail and which could be certainly an excellent subject for a PHD thesis (many things to be checked, depend on the type of instability, etc.)! => Ongoing discussions to see what can be done but we should certainly go ahead!
5) Brief reports of the 4 WGs (by the WG leader or
replacement) => Plan, activities, deadlines, issues, etc.:
a) BB (TP):
- DA studies for HL-LHC and RLIUP scenarios proposed by Gianluigi and
Oliver. Crossing angle and intensity scalings for different optics.
Unfortunately since some scenarious will need lumi leveling they assume only
beta* leveling for IP1 and IP5 and optics for the leveling scenarios does not
exist. Scan over parameters are on-going to try to extrapolate for proposed
scenarious. Another open question is which DA we take to define BB separation?
On this subject there are some discussions on-going (4-8 sigma) also with
Massimo. DA studies could be faster if database implementation will take place.
We are stuck by recollecting the results while the LHC@home BOINC system allows
us to scan and run an enormous number of cases. This needs to be implemented
ASAP! Plus the FMA implemented by Javier.
-DA studies also for Verena for 50 ns case for HL-LHC case, maybe 1 case to show comparison.
- DA studies Danilo.
- Meeting BBLR with D. Schulte. As outcome of the meeting, there is some confusion on the collimators to be modified with wire. Simulations studies need long term stability studies DA. Wire already in Sixtrack from Tevatron studies with F. Zimmermann dated 2002. With J. Barranco, understand what its doing, document, found some needs for modifications of MADX to recenter the footprint. Massimo is aware and will try to do this asap. The compensation works, now we haveFMA and DA in Sixtrack with wire. We will benchmark versus BBtrack with TatianaR, run some cases and then pass the tools to Daniel for the full study.
-Javier, FMA, crab crossing, 6D BB lens checked, BBLR wire checks on-going documented, bench,marked.
- Javier is implementing crossing angle in COMBI.
- Sasha here next week. 6D versus 4D Sixtrack versus Lifetrack.
- B. Muratori was here. He learned how to use COMBI and will look at scenarious of leveling (transverse offset and beta*), emittance effects to support weak-strong studies. Modifications of code (independent betas for IPs, Long range encounters at right phase advance and separation allowing for optics maps from MADX between encounters). Access Daresbury clusters.
-Xavier on holiday, George Coombs working, no meeting
tomorrow.
b) SC (FS and EB):
- Bernd is helping us to
upgrade our IT resources by more than doubling the number of 48 core machines to
20 and by setting up a special queue for us that we will use for our peak load.
(action FS/all).
- There has been progress with the "emittance spike" issue and the source has been found.
- Raymond reports on progress of using IMPACT for his PS tracking, apparently the code is very fast.
- Frank has written a manual for MAD-X with frozen space charge. He has finalized the code and making sure that it fits into the MAD-X development. It has to be mentioned that Frank had to intervene on several occasions with the MAD-X team to make sure that external MAD-X users can still develop the code themselves. He has just gotten confirmation both from FERMILAB and BNL that this has been successful.
- Frank has been starting the PS tracking with the frozen space charge model and in particular including a OPENMP version that has been developed in collaboration with BNL experts. In a first version a speed-up of a factor of 2.2 on a 4 core machine can be reported. At BNL an example was 4 times faster.
- The SYNERGIA collaboration is slowly progressing and Frank is in steady contact with James and his team.
- Frank has contacted Jeff Holmes and the py_ORBIT development seems to be on track with the goal of binding in PTC and benchmarking a new noise-free FMM module.
- Both codes have made progress with the Giuliano's GSI
benchmarking suite. However, this is not yet finished nor properly verified.
c) EC
(GR): pptx
d) IMPED (NM
and BS): pdf
6) Actions to be taken for the next meeting
- Old actions.
7) Miscellaneous
- Deadlines and important dates for ICE.
- The next (95th) meeting will take place on 06/11/2013 => Agenda:
1) No defined yet.
- See preliminary agendas for the next meetings.
- See List of Actions.
Minutes by E. Metral, 25/10/2013.