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organized by EuCARD-AccNet-EuroLumi and SPS Upgrade Study Team

topical workshop on Anti e-Cloud Coatings “AEC'09”. Summary for SPSU by Mauro Taborelli. http://indico.cern.ch/conferenceDisplay.py?confId=62873. organized by EuCARD-AccNet-EuroLumi and SPS Upgrade Study Team. http://eucard.web.cern.ch/EuCARD/index.html. http://accnet.lal.in2p3.fr/.

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organized by EuCARD-AccNet-EuroLumi and SPS Upgrade Study Team

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  1. topical workshop on Anti e-Cloud Coatings “AEC'09” Summary for SPSU by Mauro Taborelli http://indico.cern.ch/conferenceDisplay.py?confId=62873 organized by EuCARD-AccNet-EuroLumi and SPS Upgrade Study Team http://eucard.web.cern.ch/EuCARD/index.html http://accnet.lal.in2p3.fr/ http://paf-spsu.web.cern.ch/paf-spsu/

  2. TiN as alternative? • TiN is good if conditioned in the lab (SEY=0.85), but also other materials have similar performance • The best value presented with moderate conditioning (air exp. time unknown) is SEY=1.2 for 10-5C/mm2 • TiN is good if conditioned in machines withphotons (KEKB, SLAC…ions not quantified) • Degassing only slightly higher than Cu, improves with very moderate bake out (80C) In KEK LER Copper K. Kanazawa TiN (KEK) Shibata TiN (BNL)

  3. Conditioning in the lab: (S.Kato, KEK) As received state Dose of irradiation in the lab at 5KeV electrons S.Kato Data consistent with other labs (CERN, SLAC) S.Kato After a strong conditioning by an e-beam almost everything is good

  4. Carbon coatings: DLC as alternative to a-C? • it is worse than a-C (not the best DLC according to S.Kato, SEY=1.1 if sputter cleaned), sp2 is relevant • DLC is not simple: SiC or Cr adhesion layer+ stress releasing layer with DLC on top • ESD is better than Cu • no air exposure study As received surfaces KEKB Kato DLC K. Kato and M. Nishiwaki S.Kato

  5. Conditioning of uncoated surfaces Why does StSt condition to 1.5-1.6 in SPS and to 1.1 in the lab? No difference for Cu in lab and KEKB KEKB Laboratory 0.6C/mm2 S.Kato S.Kato

  6. Conditioning in SPS SPS transfer sample (StSt) Measurements in situ on copper (N.Hilleret) ~1.4

  7. Copper (N.Hilleret) Cu, LHC type beam in SPS, measured in situ Photons Cu lab conditioning

  8. Al particle Al2O3 particle Gold coated Surface top view Low SEY by rough surfaces (apart of grooves) • Chemically prepared rough surfaces • -SEY =1.2 at 800eV, SEY=1 at 400eV • Rough is OK in UHV only if we can bake to reduce outgassing • The surface is mechanically fragile (adhesion?) • Impedance? • With insulating particles • - SEY<1, higher above 800eV • Fundamental research necessary, principle still not understood • Would impedance hinder any application or can it be optimized? I.Montero

  9. Magnetically rough surfaces: • The best results are only for Au coated particles: is there more than the magnetic field effect or Au is “cutting off” the peak at low energy ? • Are there ideal values of magnetization, domain size and orientation? • Probably only for field free regions Au coated ferrite microparticles (topographic+magnetic roughness) Coated (blue) and uncoated (red) particles

  10. Lanfa Wang, SLAC Simulation of one side of the chamber with low SEY (G.Rumolo) Keep in mind this if we put the grooves

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