Minutes of the ICE section
77th meeting on Wednesday 27/03/2013 (08:40-10:30, 6/2-004)
ICE members: Benoit Salvant (BS), Carlo Zannini (CZ), Danilo Banfi (DB), Daria Astapovych (DA), Hugo Alistair Day (HD), Elias Metral (EM), Elena Wildner (EW), Frank Schmidt (FS), Giovanni Iadarola (GI), Giovanni Rumolo (GR), Jean-Luc Nougaret (JLN), 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: BS, CZ, DB, DA, HD, EM, EW, FS, GI, GR, JLN, KL, NB, NM, OB, SP, SRF, TP, WH, XB, JosephK, MauroM, AlexeyB, MichaelB, GuidoS, FritzC.
1) Newcomers / visitors
- None.
2) Comments on the minutes of the previous 76th meeting + Actions
- No particular comment.
3) General infos
- SL meeting:
- Travel list for 2013 and possible fundings.
- CAS@CERN:
- There will be finally 2 courses: end of 2013 and beginning of 2014.
- It is under discussion the possibility to have CAS@CERN on a regular basis. This could be every second year when there is the advanced CAS.
- CERN children work.
- Concern for the water quality in general at CERN. In the end it has been found that the issue was limited to one single water fountain in Resto 2.
- Summer students: 850 NMB applications have been received.
- CMAC:
- 50 ns should be kept as back-up plan. Concern for UFOs.
- Strong recommendation to instrument the LHC to monitor e-cloud effects.
- It has been proposed to create a small team on future studies.
- The proposal of having bunchlets (separated by 5 ns) for e-cloud mitigation would be problematic for the beam instrumentation.
- CERN GUIDES: It can be part of the MARS activities. Fellows are (strongly) encouraged to become guides.
- Not many new arrivals have replied to the department drink invitation => Please try and go and if not possible please inform LaurenceVC.
- TSC deadline for the request to DelphineR: 02/04/2013.
- News from LHC:
- TT2-111R ferrite for TCTP => VincentB presented very encouraging results. The outgassing is improved much by the treatment at 1000deg. It is now well within specs at room temperature and still acceptable at 100deg (roughly factor 3 below specs).
- Idea with GA to organise an internal review around mid June to see/discuss where we are in the understanding of the collective effects in the LHC: instabilities (chroma, octupoles, ADT), RF heating, possible scenarios for 2015, etc.
- BB2013 workshop last week:
- Some follow-up discussions => E.g. on stability diagrams with both octupoles and LR (Action 1) etc.
- It was mentioned (if I am not mistaken) that we might squeeze already with colliding beams to gain stability (required for Pb operation in run 2. Why? To be discussed with JJ) => Action 2.
- Future WG on leveling mentioned by TP. BS commented that leveling is a big issue for some experiments which will be close to the beam and will have to move => Seems that they are aware.
- RaymondW reported unexplained crashes of the ORBIT-PTC programme when running long simulations as well as issues with the number of micro-processors => Followed up by the SC team.
- Discussion with StefanoR about a collimation review which should take place ~ end of May => Should have a talk on the collimators' impedance (NM).
- Reminder on LHC impedance: factor ~ 2-2.5 in the different measurements made compared to our RW model.
- Discussion about the roughness of the collimators => Is it possible to have a look?
- BS reminded us about a factor 1.5 measured in the past between only 1 jaw and the full assembly (jaw in graphite at that time and not CFC).
- Comment from FC about the 2D model and real part of the longitudinal impedance at low frequency (Action 3).
- NM reminded us with the current plan (Action 4):
- Review past SPS data.
- Check with some plots/studies from AlexeyG about the BB impedance for small gaps.
- MikhailZ et al. from INFN are redoing EM simulations in the framework of HL-LHC and we will see if the factor ~ 2 can be explained by the geometry.
- BI review on FR 15/03/13: https://indico.cern.ch/conferenceDisplay.py?confId=234589. The aim is to present this at LMC and it was suggested to organise a second follow-up meeting in June/July to discuss the remaining open items.
- WE 13/03/2013: Email from MaurizioV about the 1st H- beam at 3 MeV: “This afternoon at 4pm an H- beam has been for the first time successfully accelerated through the Linac4 RFQ, up to 3 MeV energy”.
- Discussion at MPP workshop (https://indico.cern.ch/conferenceDisplay.py?ovw=True&confId=227895) => "We need a body to follow up heating issues – not necessarily MPP". The continous (temperature) monitoring should be done to try and anticipate pbs (as mentioned by GA).
- LIU 2013 event (https://indico.cern.ch/conferenceDisplay.py?confId=238152) on 12/04/13.
4) Lessons from the 2012 run in preparation of the start-up in 2015 for both the LHC and the other machines => How can we prepare ourselves better?: responsibilities, communication outside ICE or ABP, quicker answers, follow-up of the fills, data logging, post processing, etc.? => Everybody
- Reminder on current plan during LS1 and preparation for LHC re-start:
- Beam-beam workshop (2013).
- Space charge workshop (2013).
- Impedance workshop (~ Spring 2014).
- Internal review around mid June 2013 to see/discuss where we are in the understanding of the collective effects in the LHC: instabilities (chroma, octupoles, ADT), RF heating, possible scenarios for 2015, etc.
- Prepare for 25 ns operation:
=> Regime of ecloud.
=> Interplay with other mechanisms?
- Possible scenarios => Collide and then squeeze. When exactly? Many simulations required and to be ready for re-start.
- Discussion about difficulties during 2012, the year of the Higgs boson discovery... => We will try and be better prepared for 2015.
- For the LHC injectors:
- Develop impedance models of PSB and PS during LS1.
- Lot of work done in SPS last year with Q20 => Re-start with 25 ns for LHC and ecloud regime.
5) Actions to be taken for the next meeting
- Old actions.
- New actions:
- Action 1 (XB and AB): Clarify the situation with the stability diagram in the presence of both octupoles and LR beam-beam.
- Action 2 (BB team): Check/follow with JJ et al. all the beam-beam issues with Pb ions and if this is true that we will need to collide and squeeze for stability issues (and if yes, why?).
- Action 3 (FC et al.): Real part of the longitudinal impedance at low frequency and in particular of the SPS vacuum chamber at 43 kHz (revolution frequency).
- Action 4 (NM): Try and understand where the factor ~ 2-2.5 in the LHC transverse impedance measurements come from.
6) Miscellaneous
- Deadlines and important dates for ICE.
- The next (78th) meeting will take place on 03/04/2013 => Agenda:
1) Follow-up of previous meeting (lessons from 2012 etc.) but focusing on the follow-up of the fills, data logging, post processing, etc. (everybody).
2) Rehearsal of NM's talk for the 4th TLEP workshop (04-05/04/13).
3) Follow-up about real part of longitudinal impedance at low frequency (FC et al.).
- See preliminary agendas for the next meetings.
- See List of Actions.
Minutes by E. Metral, 29/04/2013.