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Last week

Last week. Friday: CMS magnet fast dump  warmed up to 70K LHC kindly began a program of Machine Development so that we didn’t lose too much luminosity (relative to ATLAS ) Saturday: I returned from vacation CO is a nice place, but they don’t have good baguettes

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Last week

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  1. Last week • Friday: CMS magnet fast dump  warmed up to 70K • LHC kindly began a program of Machine Development so that we didn’t lose too much luminosity (relative to ATLAS) • Saturday: I returned from vacation • CO is a nice place, but they don’t have good baguettes • Today: Magnet back to 6K  ramped back up to 3.8T • LHC finishing their Development • Tomorrow: collisions again • I have hope that LHC will now deliver consistently high lumi … next page… G. Rakness (UCLA)

  2. M. Lamont (CERN) June Machine Development / Technical Stop / ICHEP Last week • Throughout 2012, LHC has been plagued by beam losses as they squeeze from injection optics to *=0.6m • Was already there before ICHEP, but was more apparent after June TS • Have reduced intensity so as not to dump beams while they figure this out… G. Rakness (UCLA)

  3. Proposals, experiments, null results… … while they produce physics for experiments in the meantime… • Q: Problems with injectors? • This had been a problem after the April Technical Stop • A: No. Dedicated study showed the injectors are not a problem… • Q: Are bunches resonating? • That is, are non-colliding bunches not being damped by the collisions • A: No. Filling scheme changed 15 June, with no change… • Q: Sufficient to stay away from 100Hz and 50Hz external noise? • New tools developed to look at the tune (beam frequency) as a function of time • A: No. Even away from the noise, instabilities were still a problem • Q: Collide in LHCb at a different time than CMS/ATLAS? • Hard to decouple possible problems since all expts are brought into collision simultaneously • A: Not tried (yet). Will require large effort for this (diagnostic) tool… • Q: Change the sign of the octupole magnets? • Simulations indicate a very small region of tune spread (“phase space”) during squeeze • A: Next page… G. Rakness (UCLA)

  4. Stability studies – Octupoles not reversed With octupoles in their (present) polarity, beams were unstable at all measured values in octupole-chromaticity space Slide from M. Lamont (CERN) at http://lhc-commissioning.web.cern.ch/lhc-commissioning/news-2012/presentations/week32/LHC-progress-130812.pptx

  5. Reverse polarity operations Increased octupoles and then chromaticity until stable Looking good up to 1.55x1011 p/bunch Slide from M. Lamont (CERN) at http://lhc-commissioning.web.cern.ch/lhc-commissioning/news-2012/presentations/week32/LHC-progress-130812.pptx

  6. CMS peak luminosity per fill https://cmswbm.web.cern.ch/cmswbm/cmsdb/servlet/DataSummary 6.94x1033/cm2/sec = maximum instantaneous luminosity ever achieved at LHC Summary: there is hope that the LHC will be able to reproduce these luminosities and perhaps increase them… We will see… G. Rakness (UCLA)

  7. To do • Run Coordination • Follow up database check • Follow up DAQ shifter actions • Follow up ECAL/HCAL reconfiguration after clock changes • Rework shift leader training • Make shift summary Elog template for shift leader • Finish ARC work on Contact Interactions • Collaboration Wide Review ends this week • CSC • Check ALCT slow control firmware at 904… then at p5 on chamber with strange ADC values • Finish documentation of CSC timing • https://twiki.cern.ch/twiki/bin/view/CMS/CSCsynchronizationDocuments • Put firmware into SVN • RAT firmware loading • As well… • Make neutron skims G. Rakness (UCLA)

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