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MKI UFO MD. LHC Study Working Group Tobias Baer for the UFO MD Team January, 27 th 2011. Why ?. UFOs could be a major limi - tation for the performance of the LHC after LS1. 81 UFO beam dumps by arc UFOs in 2011 for 7TeV. (T. Baer, Evian 2011)
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MKI UFO MD • LHC Study Working Group Tobias Baer for the UFO MD Team January, 27th2011
Why? • UFOs couldbe amajorlimi-tationfortheperformanceofthe LHC after LS1. • 81 UFO beam dumpsbyarcUFOs in 2011for 7TeV.(T. Baer, Evian 2011) • Nosatisfactorymitigationfor MKIUFOs, yet. (cf. also M. Barnes at LIBD #66) • MKI UFO MDs aretheonlyoptiontostudy UFOs directly. • Manyresultsoptained in previous MDs.Pulsingof MKIs directlystimulates UFO production. Fast UFOs (initiallycharged?).No UFOs at MKQs (metalizedceramictubeaspossiblemitigation). Distribution of UFOs after MKI pulse measured (particledynamics).
What? • Investigate the production mechanism and dynamicsof UFOs at the MKIs by pulsing the MKIs on a gap in the partly filled machine. • Pulsingof individual MKIs. MKI asymmetryobserved. (T. Baer, CMAC #4) • Study influenceof e-cloud.Correlationwith e-cloud/vacuumactivityexpected. (Chamonix) • Study macroparticledynamics.BLM studybufferwith 80µs resolution (canresolvestructureof UFOs). • 25ns, higher beam intensity (extrapolation).Indicationof strong UFO activityobservedduring 25ns MDs. (T. Baer, Evian 2011) • Possiblyvariationof kick strengthand/or pulse length. Remainingfrom last MD.
Thank you for your attention! Tobias Baer CERN BE/OP Tobias.Baer@cern.ch Office: +41 22 76 75379 • Further information: • T. Baer et al., “UFOs in the LHC”, IPAC’11, TUPC137, September 2011. • T. Baer et al., “MD on MKIs and MKQs”, to be published soon. • T. Baer et al., “MKI UFOs at Injection”, CERN-ATS-Note-2011-065 MD, August 2011.
MD Plan • Plan: Study fourmainaspects: • Study UFOs atMKQ. • Study delayof UFO occurence w.r.t. MKI kick (UFO dynamics). • Study influenceof e-cloudsolenoids. • Study UFO asymmetrybetweenkickers (pulsing individual kickers). • What was done: • 01:45 – startverificationprocedurewithpilots, bothbeams. 3.5h • 05:20 – injecting 1236b, problemwith PS cavity. 2.75h • 08:05 – 1236b circulating, startdatataking. 2h • 08:43 – startpulsing MKI.05R8. • 08:55 – startpulsing MKI.05L2. • 09:13 – startpulsing all MKQs inbetween MKI pulses. • 09:44 – switch off e-cloudsolenoidsaround MKI.05R8. • 09:56 – beamsdumped(injectioncleaningproblem), MD recovery. 0.5h MKQ pulse in abortgap
UFO at 09:40:52 • Assumingfree fall: • UFO dynamicscannotbeexplainedbygravitationalforcealone. • Manysimilareventsrecorded. 18ms UFO MKI Pulse
UFOs at MKIs • Lossesand MKI pulsesatMKI.5L2. • 3 UFOs in 2 hours. • Lossesand MKI pulsesatMKI.5R8. • Many UFOs, especially afterMKI pulse. • Sometimesvacuumspikeafter MKI pulse. 2 UFOs after MKI pulse uncorrelated UFO MKI pulses Vacuumat MKI.D Switch off e-cloudsolenoids Injection Dump MKI pulses
No UFOs at MKQ • No UFOs around MKQs observed. • Pulsingthe MKQs 34 times, mostlyboth planes andbeamstogether. Pulsingof MKQs