- Comment by CH on the batch system which seems to be full since several weeks. Some other people had similar problems => MassimoG said that there are special queues (such as for instance u_slap with special privileges) and that there is an IT meeting on 06/12/10 where this could be discussed. He also mentioned that LHC@Home can be used for DA and beam-beam.

- This is the last meeting of the year: The meetings foreseen on 01/12/10, 08/12/10 and 15/12/10 are cancelled due to LIU day, Operation workshop in Evian and LHC-CC workshop!

- ICE section lunch on FR 10/10/10 at Cafe de Peney?

- ICE ski day => To be organised by GR.

- Impedance web meeting this afternoon with in particular a talk by NM (similar to the one given at HB2010).

- Info I sent:

- ICE requested 2 PHD students.

- CAS on High Power Hadron Machines, Bilbao, May-June 2011.

- SL meetings on 10/11 and 18/11:

- The candidature of Prof. Vaccaro as associate was accepted.

- CNGS reached its goal for 2010, i.e. 3.8E19 pot.

- In the next AFCs, Scientific Associates will be charged to the group budget instead of the department budget.

- V. Kornilov will visit us in 2011 for one week to participate in MDs in PSB. GR is following this up.

- DelphineR would like to be informed in advance about visitors and students' arrivals.

- BEMB:

- Novae will take over the service in Restaurant 2 and 3.

- Staff association is in contact with other banks to propose alternative to UBS.

- IEFC:

- No extension of CNGS run in 2010, but an extension will be granted in 2011.

- It seems there are no strong reasons against running in 2012. However, there is a request to have a 3-month winter shut down.

- ELENA is supposed to require 14 MCHF and 66 FTE (37 FTE from CERN).

- News on the LHC:

- Ecloud: Why did our group make its ecloud estimates from SEY between 1.1 and 1.7 whereas it seems to be known by everyone that for unbaked copper tube it is between 2 and 2.5?

- FZ gave a detailed talk at the LHCBCWG held on 09/11/2010 (E-cloud build-up & instabilities: expectations, observations and outlook).

- Ecloud effects:

- vacuum pressure rise: desorption yield, pumping speed,

- single-bunch instability: interplay w. impedance & beam-beam

- multibunch instability

- incoherent emittance growth

- heat load in cold arcs (quench)

- perturbation of beam diagnostics (it seems LEP had some problems with the e+ ring)

- Modeling tools at CERN:

- ECLOUD => e-cloud build up, electron flux on wall (this is what is important for the vacuum and one needs help of the vacuum group to make the translation), heat load, multi-bunch wake field.

- HEADTAIL => e-cloud driven single-bunch instability, incoherent emittance growth, interplay w. impedance & space charge.

- MICROMAPS => Precise incoherent effects.

- FAKTOR2 => For 3 D. It seems to be 2D at the moment according to GR who is the custodian.

- At top energy in the LHC one should saturate with the SR only without avalanche but due to the sawtooth it should be OK (to be confirmed).

- Measurements from R. Cimino in 2003 of the SEY (also called deltamax) vs. primary energy of the e- => Probability of elastic e- reflection seems to approach 1 for 0 incident energy and is independent of deltamax. But this is a controversial, as it is very difficult to make precise measurements at very low energy.

- Present model of SEY => Secondary e- consist of true secondaries and elastically reflected; since 2003 we assume that elastic reflection is independent of theta (as we have no data). Re-diffused means that it has some scatter but we ignore it (M. Furman includes rediffused electrons and finds that they increase the heat load by 100%). In the formulae, s is a fit parameter that was measured to be equal to 1.35 for LHC Cu samples.

- Reminder: All measurements are usually done for theta = 0, i.e. perpendicular incidence. For metallic surface it should depend on theta, but for amorphous carbon it might be isotrope as there are may be a lot of hills and valleys.

- In-situ conditioning in the SPS (2002).

- SPS benchmarking 2004, strip detector simulation:

- Surface conditions (deltamax, Reflectivity R) and detector properties are uncertain => Constrain parameters by benchmarking multiple measurements, change distance between trains & use relative measurements.

- 3 curves intersect at deltamax=1.35, R=0.3 => We will repeat this analysis for the LHC. Action 2: FZ and ecloud team.

- deltamax=1.2 was even reached at some point in the SPS!

- Simulated heat-load for nominal LHC:

- 25 ns => SEY < 1.5 needed.

- 50 ns => No problem (SEY studied until 1.7 only!).

- Why SEY not studied above 1.7? Firstly, before a certain year the ECLOUD code could not simulate a SEY > 2. Then this was solved but it seems that the ABP group was never asked to simulate cases with SEY > 2.

- Reminder: At HL (High Luminosity) we have in addition to cool the IRs, and therefore the cooling capacity decreases.

- Ecloud can lead to SBI (Single-Bunch Instability):

- SBI threshold ecloud density ~3E11 m-3 at injection and for Qprime ~ 2. But, one should have this density almost everywhere in the ring to have the instability, i.e. that it should be in the cold regions.

- At an ecloud density of 6E11m-3, the intensity threshold is Nbth ~ 6E10 p/b, still for Qprime ~ 2.

- At an ecloud density of 6E11m-3, the instability is suppressed for Qprime > 15.

- BUT, then a slow emittance growth below threshold is observed => Slow emittance growth never vanishes; precise value depends on optics & e-cloud distribution around the ring.

- Surface conditioning => Surface conditioning by e- bombardment and surface conditioning by synchrotron light

- Presentation to LHC MAC 10 June 2005 => The challenge is to decrease deltamax to 1.3 with a stable beam.

- Ecloud in the LSS:

- e- cloud simulations at 25-ns bunch spacing for the two-beam IR sections were performed by GR, Adriana Rossi and FZ in the period 1999-2002 to specify the acceptable maximum secondary emission yield in this region: nominal LHC beam & SEY values between 1.1 and 1.4 had been considered.

- New simulations for much higher SEY are being launched.

- Early preliminary LHC findings:

- At 50 ns spacing strong evidence for large e- cloud build up in warm and cold sections.

- Cold sections are of bigger concern.

- Both heat load & instability in 3rd and 4th train indicate SEY deltamax ~ 2.5 & R = 0.5 or R ~ 2.2 & R = 1.0 in the arcs.

- Average e- cloud density ~ 6E11 m-3 (deduced from Qprime effect).

- Expected tune shift ~ 2.5E-3.

- New simulations for LSS and more simulations for arcs are in progress.

- Determine R from memory effect between trains.

- Ongoing, planned & proposed studies:

- ECLOUD simulations (Humberto, Octavio):

- SPS benchmark ONGOING (Octavio)

- LHC LSS at 150 ns PLANNED (Humberto)

- Memory effect in LSSs at 50 ns PLANNED (Octavio?)

- Simulations for arc ONGOING (Humberto)

- Multi-bunch wake field and CBI rise times

- Scrubbing scenario for 2011

- Scrubbing optimization for 2011 => Help from Theo Demma and/or Ubaldo Iriso?

- Extended LHC forecast PLANNED (Humberto)

- HEADTAIL simulations (TP, KL?, GR? EB?):

- Tune shift with stripes (question by StephaneF)

- SBI threshold and growth rates

- e- cloud induced energy loss & phase shift

- Effect of transverse offset (question by WolfgangH)

- Incoherent effects - collaboration with Giuliano Franchetti from GSI (?)

- Interplay with beam-beam

- Christine talked about the material characterization for the 18 MHz to 40 MHz sweep-tunable RF system.

- The ferrite changes the magnetic permeability μ and then the resonant frequency of the cavity. With external couplers we lose efficiency.

- RF tuning cavity with magnetic bias:

- Examples for perpendicular (Friedrichs, 1991) and parallel (Gardner, 1991) bias.

- Issue: High tuning range (18-40 MHz) is needed, but no ferrite is known to cover that range.

- Parallel + perpendicular biasing possible ? (one way out proposed by Smythe in 1983...) => Leads to 2 primary goals:

- Characterization of ferrite samples with different saturation and line widths under different bias conditions in the required f-range (this required a dedicated test set-up, since supplier data does not exist PART 1).

- Verification of Smythes claims (PART 2) => Smythe suggested in 1983 to use (a 2-directional magnetic bias field):

- Transverse bias to get close to saturation (reduces losses).

- Additional parallel bias for tuning (less bias required for same μ-range).

- Smythe had no measurement data to support his claims.

- 1st requirement for a f-range of 18-40 MHz is a μ-range of approx. 5 (since f is inversely proportional to Sqrt[μ]).

- Ratio of minimum to maximum f is given by Sqrt[μmax/ μmin]; μmax is the value at minimum bias field.

- Measurement set-up:

- Building 168, belongs to ALICE.

- 1-port frequency swept measurement with NWA chosen to obtain complex S11. From S11, the complex DUT impedance is determined and the complex μ can be calculated.

- μ = μ' -j μ'' (dispersive and dissipative part), where magnetic quality: Qm= μ'/ μ''.

- Measurements done in perpendicular bias for 3 materials: Y36, G300 and G510.

- Reminder: what is needed is a μ' ratio of ~ 5 and a μ'' of ~ 0.1 (i.e. reasonable losses).

- From the measurement done on the G300 sample, it appears as if the method is promising and could work; we will continue further tests with other samples and higher parallel bias fields.

6) IR3MBC collimators status (NM): ppt

- Finally not discussed due to time constraint.

- The next (14th) meeting will take place on 19/01/2011 => Agenda: