6th Evian Workshop
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Europe/Zurich
Hotel Hilton
Hotel Hilton
Evian-les-Bains
Mike LAMONT
Description
The 6th Evian Workshop will be held on 15-17 December 2015 in the Hotel Hilton in EVIAN (74), France.
Attendance is by invitation only.
The principal aims of the workshop are to:
- review 2015 performance, availability, and operational efficiency. Identify possible areas for improvement;
- examine beam related limitations and establish a strategy for Run 2;
- a critical review of system performance;
- develop an outline of the operational scenario for 2016/Run 2 for input to Chamonix 2016.
| Chair | Mike LAMONT |
| Deputy Chairs | Malika MEDDAHI Brennan GODDARD |
| Editors of the Proceedings | Brennan GODDARD Sylvia DUBOURG |
| Informatics & infrastructure support | Hervé MARTINET |
| Workshop Secretary | Sylvia DUBOURG |
Support
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10:15
Welcome Coffee
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Kick-offConvener: Mike Lamont (CERN)
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AvailabilityConveners: Laurette Ponce, Matteo Solfaroli Camillocci
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2015 availability analysis• Introduction to fault review in 2015 o Weekly fault review, corroboration of data o Reminder on dependencies attributes • Availability charts: o Number of faults/downtime per week (periods of the year, scrubbing, TS,...) o Availability by week • 25 ns run o Downtime chart per system (including faults in the shadow) o Downtime chart with children faults assigned to parents o Downtime chart including turnaround penalty and precycles -> indentification of top 3 contributors to downtime • Availability matrices (frequency+impact by failure mode) for top 3 contributors • Ion run, injection problems • Main problems of the year and worries for 2016; recurring faults in 2015 • Comparison with 2012 • ConclusionsSpeaker: Andrea Apollonio
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QPS - operational aspectsThe status of the quench protection system after LS1 is reviewed, between challenges and major faults. The energy extraction issues are also analysed. Attention will then focus on the operational software tools and interfaces. The foreseen major modifications and improvements during YETS will be discussed.Speaker: Mirko Pojer
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CryogenicsIntroduction - cryogenic hardware configuration for Run2 (benefits and limitations of chosen operation scenario, failures and impact on operation) Cryo Maintain availability indicator - statistics (feedback from LS1 maintenance and consolidations, cryogenics vs e-cloud thermal load - retrospect and perspectives) Helium consumption and losses – statistics YETS main activities and 2016 run - proposal of operational scenarioSpeaker: Krzysztof Brodzinski
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R2E - is it still an issue?R2E and the Mitigation Strategy Radiation levels and comparison with previous run Failure analysis and strategy (Information collection, QPS, EPC, RF, Others, Summary and prevision, TID: long term problem) On-going and future developments (radiation tolerant requirements)Speaker: Salvatore Danzeca
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RF (hardware)The LHC beam intensity increase not only required the system to routinely run close to its maximum performances, but also demanded a very high operational reliability from the entire system. This talk will describe the operation of the LHC RF system during 2015, including new features, operational procedures and the lessons learned.Speaker: Olivier Brunner (CERN)
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13:00
Lunch
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OperationsConveners: Giulia Papotti, Jorg Wenninger
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CycleTurnaround time in 2015, break up into the different phases LHC cycle phases (analysis) Operational efficiency: what we have done and what we can do 2016 operational scenario (a few considerations)Speaker: Matteo Solfaroli Camillocci
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InjectionSpeaker: Delphine Jacquet
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Q and Q' snapback, decay- Improvement of tune measurement by filtering - Q and Q’ decay and snapback: theoretical behavior, measurement statistics and reproducibility - Possible improvements for 2016Speaker: Michaela Schaumann
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Optics model- 2015 measurements: the good, the bad, the ugly. - Improved beta* / waist determination (k-modulation and more), - Combined ramp & squeeze: how far could we squeeze without optics correction? - In the future, with a stable machine configuration (no more changes in beta* ...), could we just reuse the same optics correction every year (no need to remeasure every time)? keyword: can we make it faster? - Usefulness of the ballistic optics for triplet errors.Speaker: Andy Sven Langner
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16:10
Coffee
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Performance and limitations - part IConveners: Belen Maria Salvachua Ferrando, Rogelio Tomas Garcia
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LHC Emittance Growth until Stable BeamsIn 2012 emittance calculations from luminosity indicated that about 30 % potential peak performance was lost due to transverse emittance blow-up through the LHC cycle. The origin of the blow-up was only partially understood. The available emittance measurement systems gave inconsistent results. During Long Shutdown 1 the LHC transverse profile monitors underwent important upgrades to improve availability and measurement accuracy. Emittance measurements through the 2015 LHC cycle will be presented. Significant emittance blow-up is still apparent. The majority of the blow-up occurs during the injection plateau and beginning of the energy ramp. IBS is one of the main sources. IBS simulation results will be shown and compared to measurements. In addition strong vertical emittance growth was observed at 450 GeV. The status of the investigations to identify the source of the vertical growth will be given. A first estimate of transverse emittance blow-up of BCMS beams will also be presented.Speaker: Maria Kuhn
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Luminosity, Emittance Evolution & OP ScansDuring 2015 proton physics operation, beam size estimates were derived from the luminosities acquired during small VdM-like beam separation scans (the so called "OP scans"). This talk recalls the main results from such scans, e.g. fill-by-fill differences and emittance evolution in stable beams. In particular, it is shown that emittance shrinking due to synchrotron light damping was observed for the first time with proton beams. Furthermore, the luminosity evolution is analysed and the optimal fill length is derived based on average and expected turn-around times. A few comments on the luminosity imbalance between ATLAS and CMS and BCMS bunch-by-bunch emittances are also given.Speaker: Michi Hostettler
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Luminosity modeling for the LHCIn this talk, a luminosity model based on the three main components of the LHC luminosity degradation (intrabeam scattering, synchrotron radiation and luminosity burn-off), is compared with data from runII. Based on a Fill-by-Fill and a bunch by bunch analysis and observations, other sources of luminosity degradation will be discussed. Finally missing pieces and next steps will be briefly discussed.Speaker: Fanouria Antoniou
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How to survive a UFO attackUFOs in the LHC have proven to be a potential threat to machine availability. While the correlation of peak losses with beam intensity had initially indicated a potential limitation, the fast advance of the conditioning effect appears to have saved the day. In this presentation we will present our current understanding of the UFO threat, the BLM strategy to optimize machine availability and machine protection, and the various lines of attack for UFO-related R&D.Speaker: Bernhard Auchmann
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LHC aperture and ULO restrictions: are they a possible limitation in 2016?Frequent multiple-UFOs events in C15R8 that trigger a beam dump were often observed during the LHC commissioning in April 2015. Detailed local aperture measurements revealed the presence of an unidentified lying object that induces such losses. A quantitative and systematic overview of all the observations and measurements performed in 2015 it is shown. In conclusion the present situation and a possible strategy to deal with this object during 2016 it is discussed. An overview of beam loss behaviour along an LHC cycle it is also given.Speaker: Daniele Mirarchi
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20:00
Dinner
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10:15
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Performance and limitations - part IIConveners: Belen Maria Salvachua Ferrando, Rogelio Tomas Garcia
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Instabilities and beam induced rf heating in 2015Instabilities were observed during operation at injection, flat top and during the betatron squeeze. This resulted in high chromaticities and octupole currents in all stages of the machine cycle. A series of dedicated measurements at flat top and end of squeeze of the instability threshold was performed which can shine a light on expected performance in 2016. Beam induced rf heating will also be reported on, with emphasis placed on the performance of the MKI kicker and the effect of the bunch length.Speaker: Lee Robert Carver
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Electron cloud effectsThe brief experience with 25 ns beam in the LHC at the end of Run 1 suggested that the electron cloud effects were set to pose important challenges to the machine operation during Run 2. In spite of four weeks of dedicated scrubbing run, the 2015 proton run of the LHC fully confirmed this expectation, with the electron cloud severely degrading the beam quality at the beginning of the scrubbing run and then limiting the number of bunches at 6.5 TeV, due to strong heat load in the cold regions. This contribution will first describe the main e-cloud observations and limitations encountered during the 2015 run. The dedicated scrubbing periods at 450 GeV, the intensity ramp up with 25 ns beams at 6.5 TeV and tests with special beam variants (doublets, 8b+4e) will be covered. Finally, based on the acquired experience and the lesson learnt in 2015, a proposal for the scrubbing strategy and 25 ns intensity ramp up in 2016 will be presented.Speaker: Giovanni Iadarola
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Beam-beam Head-on and Long RangeThe 2015 LHC run has shown the beauty of having weaker beam-beam effects with respect to 2012 physics run. The 2015 set-up has been defined to allow Landau octupole and chromaticity to be powered at maximum currents to fight coherent instabilities. Quantitative studies of the impact of reduced crossing angles on the beam and luminosity lifetimes have been used to compare to expectations from Dynamical Aperture studies. Possible scenarios for the 2016 RUN will be presented highlighting the beam-beam limits expected from long range and head-on.Speaker: Tatiana Pieloni
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10:00
Coffee
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Systems: part IConveners: Chiara Bracco, Roderik Bruce
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TDITDI limitations and observations up to now (any understanding for vacuum spikes and difference B1, B2) Design of new TDI to be installed during Xmas stop. Any further limitation? Any other limiting element for 288 bunches? Table of parameters for different beams (nominal, BCMS, highlight Run2 ones).Speaker: Anton Lechner
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ADTImprovements applied during LS1: did they fulfill all expectations? Features, present uses of the ADT in different contexts Issues and possible mitigation for 2016 run. Operation with doublets. Are ADT settings clear for operators or need of experts?Speaker: Gerd Kotzian
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RF (Beam)Improvements applied during LS1: did they fulfil all expectations? Features (parameters used in 2015), issues and possible mitigations for 2016 run. bunch length reduction observed and its mitigation, longitudinal blowup, maybe something on bunch length stability threshold preparation of RF for higher power. commissioning time? Operation with doublets.Speaker: Helga Timko
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12:25
Lunch
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Systems: part IIConveners: Chiara Bracco, Roderik Bruce
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CollimationImprovements applied during LS1: did they fulfil all expectations? Experience during commissioning and operation: any issues encountered? Possible mitigations for 2016 run. Collimators with BPM: operational experience and orbit stability. Loss maps: optimized procedure and with reduced number of fills.Speaker: Gianluca Valentino
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DiagnosticsSpeaker: Enrico Bravin
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Beam profile measurementsImprovements applied during LS1: did they fulfill all expectations? Features, issues and possible mitigation for 2016 run. Different measurements: BSRT (and related equipment), interferometry, wire scanners, BGI and BGVSpeaker: Georges Trad
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Controls - an OP perspectiveEvolution from 2012 (see Delphine's Evian talk) Change of machine configuration: can it be improved Migration to FESA 3, really transparent? OP and CO development philosophy OP priorities: are they the same as CO’s?Speaker: Kajetan Fuchsberger (CERN)
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Feedback on Controls from 2015 operation.What worked well, what should to be improvedSpeaker: Marine Gourber-Pace (CERN)
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15:45
Coffee
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Machine ProtectionConveners: Markus Zerlauth, Wolfgang Bartmann
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Have we been operating safely in 2015?During LS1 most machine protection systems (MPS) have undergone significant changes. A full (re-) commissioning of the MPS has been performed before and respectively during beam commissioning in 2015, followed by a step-wise intensity ramp-up to reach nominal beam intensities. This contribution will summarize the results of the MPS commissioning and the intensity ramp-up, focusing on issues like near misses and false triggers. The implementation of the new approval strategy for machine protection relevant MDs will be critically reviewed. A list of machine protection systems with remaining issues and required improvements will be presented. Finally, an outlook on the proposed machine protection strategy for 2016 including a first proposal for the intensity ramp-up will be provided.Speaker: Daniel Wollmann
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How to obtain clean injection?During 2015, injections of 144 bunches into the LHC induced losses of up to 88% of the dump thresholds on the TDI. During run 2 these losses were studied in greater detail with diamond based particle detectors. It was found that the main loss contribution is due to ghost bunches, originating from the SPS, swept over the TDI during the rise and fall time of the injection kicker magnet MKI. This contribution will summarize the measurement results (transversal and longitudinal losses) in comparison to run 1. In addition, possible loss mitigations, already applied for a first time during an MD, will be discussed in view of injections of 288 bunches planned for operation in 2016.Speaker: Florian Burkart
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BLM thresholds evolution and 2106 proposalIn total, over 5700 changes to the BLM thresholds were made during 2015. The new thresholds are based on the operational experience from Run 1, on new simulation models and on results from quench tests performed so far. Following the first experiences with operation at 6.5 TeV, a series of adjustments were made throughout the first operational year of Run 2. An overview of the main changes since the start of the LHC operation and their impact on the machine protection will be presented, focusing on the impact on availability during operation in 2015. The presentation will conclude by discussing the remaining main updates, and by proposing a threshold strategy for the start-up in 2016.Speaker: Matti Kalliokoski
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BLM thresholds and damage limits for collimatorsLHC operation at 6.5TeV required major changes of the collimator BLM thresholds adopted in Run 1. At startup in 2015, the BLM thresholds at collimators were set by scaling the values in 2012 to 6.5TeV. This approach enabled a smooth commissioning during the intensity ramp up period. Throughout 2015, thresholds have been further optimized to allow for 200kW primary betatron losses, to accommodate luminosities beyond 1e33cm-2s-1 and to avoid unnecessary dumps triggered by UFO events around the experimental insertions. The changes deployed in 2015 are presented. On-going studies to improve the understanding of collimator losses, based on beam measurements as well as on detailed simulations are discussed, along with a proposal of the 2016 collimator BLM threshold strategy.Speaker: Alessio Mereghetti
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BI for machine protectionThis contribution reviews the status of three main beam instruments currently in use for machine protection purposes: the IP6 interlock BPMs, the Beam Current Change Monitor (BCCM) and the abort gap monitor (BSRA). Their performance during 2015 operation and observed limitations will be discussed as well as plans for future improvements and/or alternative solutions in order to allow for reliable operation in view of operational demands in 2016.Speaker: Thibaut Lefevre
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19:30
Aperitif
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20:00
Workshop Dinner
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2016Conveners: Giovanni Iadarola, Stefano Redaelli
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2016 machine configuration: can we get to 40 cm?Outcome of series of beta* MD, proposal for configuration for 40cm (summarizing ABP inputs - coll, BB, impedance, and MPP constraints) Alternative configurations (50cm? risk mitigation vs lumi gain)Speaker: Roderik Bruce
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How to fight collective effect limitationsStrategy Instabilities at injection, flat-top, squeeze, in collision. non-colliding bunches. E-cloud related limitations (filling scheme optimization), sensitivity to beam parameters (emittance, Ib, bunch length)… other available knobs? What diagnostics do we need to have in place?Speaker: Kevin Shing Bruce Li
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HW commissioningplus machine checkout. What needs to be done? When can we start? How long will it take?Speaker: Mirko Pojer (CERN)
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09:45
Coffee
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2016Conveners: Giovanni Iadarola, Stefano Redaelli
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Initial commissioning to Stable BeamsFirst month of commissioning to first stable beams. Break down of commissioning steps per system. Include list of measurements for validation of final beta*. Preparation needed for scrubbing (high intensity at 450 GeV). MP intensity ramp up.Speaker: Belen Maria Salvachua Ferrando (CERN)
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MD priorities for Run 2Very broad overview of results from 2015 and priorities going forward. Include possible optimization on the use of the MD timeSpeaker: Jan Uythoven (CERN)
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Wrap-upConvener: Mike Lamont
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Wrap-upSummary of key points and follow-up from workshop. Include expected performance in 2016 (briefly) along with schedule outline (including special runs etc.).Speaker: Mike Lamont
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11:40
Finger food
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12:40
Bus Departure to CERN
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