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s tatus report from ad-hoc study group* on experimental UFO study programme

s tatus report from ad-hoc study group* on experimental UFO study programme. *this study group established as an ACTION from LMC#95 (8 June 2011). Frank Zimmermann LMC meeting #109, 5 October 2011. UFO study meeting organization. UFO study meeting organization. UFO study-group meetings

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s tatus report from ad-hoc study group* on experimental UFO study programme

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  1. status report from ad-hocstudy group* on experimental UFO study programme *this study group established as an ACTION from LMC#95 (8 June 2011) Frank Zimmermann LMC meeting #109, 5 October 2011

  2. UFO study meeting organization UFO study meeting organization • UFO study-group meetings • Meetings ~every 6 weeks with minutes, ~16 presentations so far • web sitehttps://cern.ch/lhc-ufo • organized by Frank Zimmermann • MKI UFO meetings • MKI UFO status reported at LMC #105 • organized by Brennan Goddard • web sitehttps://proj-lti.web.cern.ch/proj-lti/LTIcoordination/RelatedMeetings/LIBD/LIBD.htm • MKI dust meetings • organized by Volker Mertens • web site https://espace.cern.ch/te-dep-abt/tc/Lists/MKI%20dust%20meetings/AllItems.aspx

  3. study-group participants participants in study-group meetings Tobias Baer, Eduardo Del Busto, Mike Barnes, Francesco Cerutti, Bernd Dehning, Riccardo De Maria, Alfredo Ferrari,NuriaFuster, Eva Barbara Holzer, Massimiliano Ferro-Luzzi, Miguel Jimenez, Anton Lechner, Eduardo Nebot del Busto, KazuhitoOhmi (KEK), Marc Ross (FNAL), Yasunori Tanimoto (KEK), Jan Uythoven, Bob Velghe, Vasilis Vlachoudis, JörgWenninger, Frank Zimmermann additional input addt’l input • Ralph Assmann, SwapanChattopadhyay (CI), Brennan Goddard, Volker Mertens, Lenny Rivkin (PSI), John Seeman (SLAC), UliWienands (SLAC), …

  4. lines of attack • survey “dust” studies at other accelerators (KEK PF-AR, CESR, SLAC PEP-II, ISR, LEP) • LHC observations • UFO dynamics studies • FLUKA simulations • MDs (so far only for MKI UFOs) • hardware studies - vibrations, dust etc(MKI) • future MDs, mitigation measures

  5. UFO & dust distributions 3670 arc UFOs (>cell 12) at 3.5 TeVwith signal RS01 > 1∙10-3Gy/s. T. Baer measured UFO strength distribution measured dust distribution consistent with observed UFO strength distribution number M. Jimenez dust contamination measured in SMI2 most of the dust consists of silica; deviations at large dust sizes are due to human interventions and could be steel, silver, Ti, etc size3 (mm3)

  6. model trajectories for falling objects trajectories for different beam intensities & twoinitial x positions N. Fuster A=1015, s=0.3 mm, x0=1.0 mm A=1015, s=0.3 mm, x0=0.3 mm repulsion after charging up – macroparticles do not reach the beam center; possibility of multiple loss events with ~80 ms separation A=1014, s=0.3 mm, x0=0.1 mm

  7. predictions vs observations – loss shape predicted temporal loss shapes N. Fuster Np,tot=1.4×1014, σ = 0.3 mm predicted & observed loss durations comparable; asymmetry in loss profile contains information on macroparticle mass 1 ms macroparticlemass (protonmassunits) T. Baer observed loss shape 1 ms temporal loss profile of UFO on 23.08.2010

  8. predictions vs observations – loss duration predicted loss duration versus intensity N. Fuster Np=1012 σ = 0.3 mm Np=1013 Np=1014 UFO duration gets shorter with higher beam intensity E. Nebot Np=1013 Np=1014 observed loss duration versus intensity

  9. size of UFO particles model prediction for total # of lost protons FLUKA simulations with MKI BLMs A. Lechner N. Fuster Np= 1014 DNp =106 1013 DNp =104 A=1017 A=1015 ~104-106 interactions for UFOs with radius 1 - 25 mm ~109 nuclear interactions / UFO • mm-size UFOs at MKI?

  10. predicted beam-size dependence total # of lost protons N. Fuster • → 7 TeV might be worse; • could this dependence also explain why MKI-D sees more UFOs? designintensity, Ntot=3.2×1014

  11. model predictions still to be tested N. Fuster loss duration versus beam size • protonlossismaximumforNp,tot=1013 and decreaseswithfurtherincreasingbeamintensity (slide 9) • lossdurationincreaseswithlargerbeamsize • non-monotonicdependencies: protonloss versus transversebeamsize (slide 10); peaklossrateversus beamcurrent • particletemperaturestaysbelowmeltingpoint Ntot=3.2×1013 peak loss rate versus A and Ntot log (peak loss rate [1/s]) • data analysis/MDs to test these addt’l predictions

  12. desired model extensions • refinementstothemodelchargingrate • e.g. position dependentpotential (metal vs dielectric) & energyloss of delta electronsinsidethemacroparticle • correctionsforfinite UFO size • e.g. UFO particleslargerthanthebeamsize • other UFO shapes • notonlysphericalobject, bute.g. needles, foils,… • further model improvements are planned – resources?

  13. PEP-II dust thumper still mounted on the HER collimator; UliWienand’s finger is on the leads of the solenoid; the black pin sticking up is the rod that gets moved by the solenoid

  14. dust injectors TRISTAN AR,H. Saeki, early 1990’s TRISTAN AR, S. Kato, mid 1990’s Y. Tanimoto • need controlled dust injector (L. Rivkin) PF-AR, Y. Tanimoto, late 2000’s XFEL future, J. Hajdu

  15. cleaning techniques efficient dust-removal techniques in SRF & SC communities Dry Ice nozzle – Reschke /DESY M. Ross Jets of single-cell HPR system • Particle removal in semiconductor industry: • High Pressure Jet Cleaning • Snow Cleaning • Ice Scrubber Cleaning • Ultraviolet - Ozone Cleaning • Megasonic Cleaning • Isopropyl Alcohol Vapor Displacement • Aerosol Jet Cleaning (supersonic aerosol jet) • Laser Steam Cleaning • (Kneisel and Lewis) water pressure variation on TESLA cavity • in-situ cleaning?

  16. proposed 3-step strategy • “hammer” to induce UFOs • - SLAC thumper will arrive mid November (U. Wienands) • - proposal to install it in IR7 (many BLMs, but no beam dump) • during Xmas break ; MDs in 2012 • - later hammer at warm-cold transition? • dust injector (in IR7) • - use modified (spare) BGI to inject dust • - or build dedicated micro/nano-technology injector • - learn/borrow from SASE FELs (nano-cluster injector guns) • cleaning • - turbulent He flow through beam screen to shake chamber? • - procedure as for RF cavities – dry-ice nozzle on robot? • - send “hairy ball” through arc chamber (L. Rivkin’s proposal) • each step to be decided • and approved

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