Minutes of the ICE section

96th meeting on Wednesday 27/11/2013 (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, SimonW, VincenzoF, MichaelB, HannesB.

 1) Newcomers / visitors

- NB has been hired as fellow as of 01/02/2014 => Congratulations!

- WH left the section and moved to CC3 => Thanks for all and best wishes for the future activities.

2) Comments on the minutes of the previous 95th meeting + Actions

- Any comment? => Minutes should be sent soon...

- List of Actions.

3) General infos

- No particular comment from anyone.

- SL meeting:

- EOY party => TH 19/12/13.

- Wish list for travel in 2014 => Did I receive everything?

- Reminder: we should try and free the rooms we reserved and finally did not use.

- BE-workshop => This week, MO to WE and RoderikB and AlessandraL will go => 3 themes: Relationship to management, Cultural life at CERN, Navigating into the department.

- High non-attendance to language course (a low attendance seems to be < 90%).

- PippaWells (PH) will be the new chair of AFC committee.

- FCC: MichaelB will be the person in charge and he together with LucioR, Steinar, MaurizioV will be attached to FreddyB as project office unit. RG will stay in BE and is the only exception.

- Summary of ELENA review. No big surprise and no showstoppers identified. Ecooling part not very detailed and it would be certainly good at some point to publish the status.

- Joel Chaskalovic from "Université Pierre et Marie Curie, Jussieu, France" will come on Wednesday 18/12/2013 to discuss the Vlasov-Maxwell equation and numerical solutions => Would like to benchmark their results with real data.

- I reserved the room 6-R-012 for those interested from 14:00 to 17:00 (...before we have the ICE lunch...):

- I asked him to present what he is doing and what he needs.

- We will briefly show him what we are doing => Space charge, beam beam, impedance-induced instabilities and ecloud.

- He would like to have some names of people and subjects of articles "pour un numéro spécial aux Comptes Rendus de Mécanique de l'Académie des Sciences de Paris intitulé (pas définitivement): Approches théoriques et numériques des équations de Vlasov-Maxwell." Please tell me who is interested and would like to publish something. I could inform him and you would receive an official email from him, who is invited the editor in chief.

- LPL review summary => Any comment?

- Comment from Hilumi workshop?

- Hilumi => Several talks from the team.

- Next steps discussed.

- Nice PS impedance web page => Action: do now the same for HL-LHC.

- Discussion with Daniel Schulte about the future pp collider => VHE-LHC:

- Would need ~ 1-2 FTEs in total.

- 4 items to be covered:

- IBS at injection and higher energy.

- Impedance => Coordinate and study the impact.

- Ecloud => Smaller bunch spacing would be ideal, like 5 ns.

- Beam-beam => We would have 5 times more encoutered at 5 ns...

- CDR foreseen for 2017.

- DanielS should organise a meeting at the end of December and we could try and decide on a reasonable assumption for the vacuum chamber.

- Impedance 2014 workshop => Ongoing.

- IPAC14 => Main author vs. presenter => Everything updated?

- Discussion with JorgW who would need some esitmates (scalings etc.) of the impedance for FCC.

- French / swiss cards (work permit) => Reminder on the importance to have your papers up-to-date: these cards represent your work and resident permits and that non-renewal of expired documents could be prejudicial to the Organisation => Please contact the cards office: cards.service@cern.ch.

- Material / money needed for impedance measurements => Should be discussed in detail during impedance meeting with all the people to see if we really need to buy that and justify our requests.

- Comment from VincencoF on VIAs: 2011-12 VIAs can apply for the 2014 fellowship committee but it is not clear for the future.

- D. Banfi and T. Pieloni gave two presentations at Daresbury Larp Meeting: one on Dynamic aperture studies for the different HL-LHC optics second on the beam-beam activities for the HL-LHC.

- DA studies are on-going (D. Banfi) to reproduce LHC long-range measurements of 2011 and 2012. Moreover first scans wth crab crossing also on-going. danilo has also implemented an automatic collection of LHC@home results while finishing and copying them to the database. This is to spead up the 1 week time to recollect results.

- J. Barranco is finishing the implementation of the 6D beam-beam head-on collision in COMBI. Then will start first benchmarks versus Beambeam3D with S. White.

- B. Muratori start working on COMBI to simulate leveling scenarious.

- With EPFL student G. Coombs luminous region calculations are on-going in the frame of the leveling working group with Jorg and Co. He is reproducing the luminous region for different leveling techniques and for different distributions. And results will be compared with measurements where possible.

-The deadline for submitting the proceeding to the beam-beam workshop is setted to the 1st December. Proceeding will be then published as Yellow report.

- Benchmark of Sixtrack 6D and crab crossing still on-going, but up to now everything is consistent in Sixtrack.

- Xavier is on military leave till 1st december.

- The 2 weekly SC meetings, reserved till end of 2014, now tend to go over the full length of 2h.

- We have started a series of educational talks and Vincenzo's clear talk about the detailed analysis of particles evolution in the tune space under the space charge force and in a fully filled RF bucket has been the first of this series. We are planning to speak about:
- The concept of phase advance and tune in 4D and 6D,
- Symplecticity in systems with deterministic chaos,
- Form factors for SC,
- Understanding of 1D resonances (several talks needed),
- Extension to 2D and 3D resonances,
- Special educational contributions by visitors like Giuliano
and others.

- We have made considerable progress with Harry and Elena to understand our issue about PTC-ORBIT. It is fair to say that we are close to solving this. As usual it is only done when it is done!

- We have intensified our collaboration with the ORBIT authors from SNS and we had a SKYPE session to agree on a plan for the near future. First prority is to integrate PTC into py_ORBIT which will be christened PTC-py_ORBIT. In the release, still planned before the end of the year, our bug fixes should be integrated. The manual should be produced automatically by proper programming tools. They promised to turn the SuperCode input files of our examples into the required PYTHON scripts. For benchmarking purposes we have provided on our SCweb pages the PSB and PS examples where we found our problems together with our latest code that includes Elena's PTC fixes. The FMM module, that according to Jeff should not suffer from the same noise level as the other SC models, has been implemented into py_ORBIT but still needs to benchmarked. It should be available in PTC-py_ORBIT in spring 2014.

- Out alternative code for our studies is SYNERGIA and since quite some time we are working on a couple of issues that concern the CHEF and the IMPACT part of the code. To make faster progress we have agreed on having regular SKYPE sessions as often as twice a week until we get this done. We have already agreed on a program of work that should satisfy all our needs for the LIU studies. This should also include the much needed manual. The first release with the main implementation should be expected by spring 2014.

- For both codes we are in the process to complete the Giuliano benchmarking. Our plan is to have this done by spring 2014.

- There has been progres with the parallelization of MADX-SC which includes a frozen space charge model. This work has been performed following my visit at BNL. We have agreed that for the completion of the work a visit by Frank for 2 weeks in February will be required.

Since the last report, two electron cloud meeting took place  https: //indico.cern.ch/conferenceDisplay.py?confId=277233 https://indico.cern.ch/conferenceDisplay.py?confId=281273. The first one was mainly a rehearsal of Octavio's talk for the defence of his PhD thesis. Furthermore, since he compared SEY thresholds for different future scenarios and different LHC filling patterns, we had a longer discussion on the effect that model assumptions and parameters have on defining the thresholds. In particular, the shape of the SEY curve and its behaviour at low energy can change the position of the thresholds quite dramatically. After some sensitivity studies conducted by Gianni in the past, it turns out that it is not only the probability of elastic reflection of low energy electrons (R0) that can affect the simulation results, but also the position of the dip at low energies. Another important parameter is the Emax, i.e. the energy for which the maximum SEY occurs. Also the amount (and position) of primary electrons can change the threshold position. Therefore, different results can be obtained when the electrons are initialised from gas ionisation (few and in the middle of the chamber) or photoemission (many and not the chamber wall), for example. The second meeting was held together with our TE-VSC colleagues, and was mainly meant to inform them of the progress in our understanding of the electron cloud in LHC and the process of scrubbing, with the goal to obtain some hints from them concerning the interpretation of the observations and possible things to take into account for the 2015 start up. Besides, the LBOC has been following up the production of doublet beams and their potential use in LHC to improve scrubbing in 2015. In the meeting at the beginning of November, issues in the injectors and in the LHC instrumentation were summarised and discussed. There are potential issues in the SPS (i.e. accelerate the required intensity and keep a good beam quality with respect to electron cloud and longitudinal stability) and in the LHC interlocked BPMs, which could give wrong readings. In the LBOC held on 26 November, the RF compatibility was analysed (and found to be OK) as well as the damper issues. It seems that the damper can deal well with 5 ns doublets, while it would be blind for a short time during splitting for the 2.5 ns doublets. On 27 November 2013, a first plan on the LHC scrubbing in 2013 is presented at the LMC.

- See Slides.

5) Actions to be taken for the next meeting

- Old actions.

- New actions:  

6)  Miscellaneous

- Deadlines and important dates for ICE.

- The next (97th) meeting will take place on 04/12/2013 => Agenda:

1) (Rehearsal) talk before giving a talk outisde ICE / ABP => Do we have any?

- See preliminary agendas for the next meetings.

- See List of Actions.

Minutes by E. Metral, 28/11/2013.