LHC Beam Operation Workshop - Evian 7-9 December 2010

Hilton, Evian

Hilton, Evian



The LHC Beam Operation workshop will be held on 7, 8 and 9 December 2010 in the Hilton Hotel in EVIAN (74), France.

Attendance is by invitation only.


The principle aims of the workshop are to review 2010 LHC beam commissioning and beam operations experience, and to look forward to the operation of the LHC in 2011.

Issues addressed will cover: operation from injection to stable beams; beams measurements and observations versus expectations; problems encountered; the performance of software and controls; the performance of the machine protection system; and necessary improvements across the board. The readiness of the machine as a whole for operation with high stored beam energies will be discussed.

The operations plan for 2011 will be presented and discussions will address the strategies for increasing luminosity, increasing intensity and other measures that pertaining to the luminosity targets of 2011.


Chairman Mike LAMONT
Scientific Secretary Malika MEDDAHI
Editor of the Proceedings Brennan GODDARD
Informatics & infrastructure support Pierre CHARRUE
Workshop Secretary  Flora MERIC, Sylvia DUBOURG
  • Alick Macpherson
  • Andrea Boccardi
  • Andrew Butterworth
  • Annika Nordt
  • Anthony Rey
  • Benjamin TODD
  • Bernd Dehning
  • Bernhard Holzer
  • Brennan Goddard
  • Bruno Puccio
  • Chiara Bracco
  • Christos Zamantzas
  • Daniel Deboy
  • Daniel Wollmann
  • David Belohrad
  • Delphine Jacquet
  • Django Manglunki
  • Eduardo Nebot Del Busto
  • Elena Chapochnikova
  • Elias METRAL
  • Enrico Bravin
  • Eric Veyrunes
  • Etienne Carlier
  • Eugenia Hatziangeli
  • Eva Calvo Giraldo
  • Eva Barbara Holzer
  • Ezio Todesco
  • Fabio Follin
  • Frank Zimmermann
  • Gabriel Johannes Mueller
  • Georges-Henry Hemelsoet
  • Gianluca Valentino
  • Gianluigi Arduini
  • Giulia Papotti
  • Glenn Vanbavinckhove
  • Grzegorz Kruk
  • Guy Crockford
  • Helmut Burkhardt
  • Jan Uythoven
  • Jean-Jacques GRAS
  • John Jowett
  • Jorg Wenninger
  • Jose Maria (Chilo) Garabatos Cuadrado
  • Kajetan Fuchsberger
  • Karel Cornelis
  • Katarina Sigerud
  • Lasse Normann
  • Laurette Ponce
  • Lene Norderhaug Drosdal
  • Louis Pereira
  • Malika Meddahi
  • Marc Tavlet
  • Marek Gasior
  • Marek Strzelczyk
  • Marija Cauchi
  • Mario Miguel Terra Pinheiro Fernandes Pereira
  • Mariusz Sapinski
  • Markus Albert
  • Markus Zerlauth
  • Massimiliano Ferro-Luzzi
  • Massimo Giovannozzi
  • Matteo Solfaroli Camillocci
  • Mike Lamont
  • Mirko Pojer
  • Oliver Bruning
  • Paul Collier
  • Philippe Baudrenghien
  • pierre charrue
  • Ralph Assmann
  • Ralph Steinhagen
  • Reyes Alemany Fernandez
  • Rhodri Jones
  • Richard Jacobsson
  • Roderik Bruce
  • Rogelio Tomas
  • Roger Bailey
  • Roncarolo Federico
  • Rossano Giachino
  • Rüdiger Schmidt
  • Schmidt Frank
  • Simon Mathieu White
  • Stefan Roesler
  • Stefano Redaelli
  • Stephane Cettour Cave
  • Stephane Fartoukh
  • Stephen Page
  • Steve Myers
  • Steven Hancock
  • Suykerbuyk Ronaldus
  • Tatiana Pieloni
  • Thibaut Lefevre
  • Tiziano Camporesi
  • Tobias Baer
  • Verena Kain
  • Walter Venturini Delsolaro
  • Werner Herr
  • Wojciech Sliwinski
  • Wolfgang Bartmann
  • Wolfgang Hofle
    • 16:00 16:30
      Welcome Coffee 30m
    • 16:30 16:45
      Opening remarks
      Convener: M. Lamont
    • 16:45 19:00
      Session 1: LHC beam operation: review of 2010 and settings the scene for 2011

      Chair: Roger Bailey; Scientific Secretary: Giulia Papotti

      • 16:45
        Performance and results 20m
        This talk will present what the LHC experiments would like to see in 2011, in terms of delivered luminosity and beam conditions. An attempt will be made to see how this could fit in a run scenario, including a heavy ion run. Special conditions will also be discussed, like sqrt(s) = 2.76 TeV proton physics, medium large beta star proton optics. First feeback on some observations that were made end of this year will be given, e.g. on beam-gas background, satellite bunches, BCM thresholds. A critical review of 2010 operation will be made (handshake, use of beam modes, operational procedures, etc.), with emphasis on issues and proposals for improvements for 2011 (and further).
        Speaker: M. Ferro-Luzzi
      • 17:05
        Operational efficiency 20m
        An overlook on the beam and machine statistics in the 2010 run is given. We report on the machine availability and efficiency for physics and give a breakdown of the downtime according to the various technical systems. We revise the frequency and duration of the technical stops with respect to their impact on the machine availability. Finally the tools presently available for the collection of this kind of data are reviewed and needs for 2011 are defined.
        Speaker: W. Venturini Delsolaro
      • 17:25
        The LHC RF: Operation 2010 and Plans for 2011 20m
        We will first briefly present the intended RF operation, as of the original Design Report. We will then review the operation 2010: From the first collisions of single bunch pilot to the emittance blow-up required for nominal single-bunch intensity. RF noise will be briefly mentioned and results of bunch lengthening during physics will be presented. The difficulties to fill the machine given the intolerance of the BLMs to radiation created by capture loss will be reminded. There will be a brief summary of klystron and cavity faults. The second part will address operation 2011. The planned improvements will be presented (longitudinal damper, tools to ease energy matching, upgrade of the RF measurements). Finally the cavity impedance issue will be revisited with emphasis on the stability with RF feedback and the scenario of a klystron trip will be studied.
        Speaker: P. Baudrenghien
      • 17:45
        Beam quality and availability from the injectors 20m
        The success of the first year of operation of the LHC would not have been possible without the hard work from the whole injector chain. Beams with different intensity, emittance and bunch spacing have been produced and tuned according to the often varying needs of the LHC. A review of the produced beam parameters is given, as for example transverse and longitudinal emittances, equality between bunches, presence of satellites. Additionally a critical view on how time could have been saved and which tools could be improved for the future is also given.
        Speaker: G. Papotti
      • 18:05
        50 and 75 ns operation 20m
        Two machine development sessions have been performed in order to understand potential limitations for the operation of the machine with 50 and 75 ns beam spacing. The main results of the studies and a possible outlook for 2011 will be presented.
        Speaker: G. Arduini
      • 18:25
        Intensity ramp-up 20m
        Total beam intensity in 2010 saw a slow ramp up during the first months of commissioning. Following bunch train commissioning and qualification the rate increase significantly. A critical look at the year's progress is presented. Given this the potential strategies for 2011 are examined with particular attention given to machine protection qualification. Issues to be addressed include: the speed of the process; the need, or not, for another MPP review; the use, or not, of more formal approach.
        Speaker: M. Lamont
      • 18:45
        General discussion 15m
    • 20:00 22:00
      Dinner 2h
    • 09:00 10:40
      Session 2: Driving the LHC

      Chair: Gianluigi Arduini; Scientific Secretary: Mirko Pojer

      Discussion Summary
      • 09:00
        How to improve turn-around 25m
        Where did we lose time (injection, ramp, squeeze, etc.). What can we do to minimize that (in the LHC and injectors)? Critical review of the operational procedures Squeeze: what can be improved? shall we still consider the option of a combined ramp and (partial?) squeeze? What are the implications of that: setting-up time, controls, reliability, machine protection. Impact on collimation, feedbacks
        Speaker: S. Redaelli
      • 09:25
        Software and control issues 25m
        The software applications and fixed displays in the control room are the unique windows to the LHC, the interface used to give it orders, diagnose its state of health and control its behaviour. The better tools we have to communicate, the more efficient is the operation team to detect and cure problems, and also run the accelerator in an efficient way. Despite the impressive number of well working applications available in CCC, there is still room for improvement. This presentation will describe the main difficulties and issues encountered during 2010 LHC run that could be solved by improving the existing software applications, or by creating new user interfaces.
        Speaker: D. Jacquet
      • 09:50
        Can we improve the magnetic model/cycle and its effects? 25m
        We recall the precycling strategy defined for operation and we give an overview of how it has been applied in the 2010 run: in how many cases the previous physics run has been used as a precycle, in how many cases we precycled the magnets, and how we did it w.r.t. specifications. 2010 run was characterized in some periods by non-nominal conditions such as lower ramp rate (2 A/s) in the main magnets and lower current (2 kA, 4 kA and 6 kA) as a main magnet flattop current. We will review these different phases and try to correlate with the beam observables. We analyse the reproducibility of tune and chromaticity, giving an estimate of the present precision of the magnetic model and discussing if it is possible to improve it. We review how the hysteresis is presently treated in the field model, and its drawbacks on the beta beating corrections during the squeeze. Possible strategies to solve the hysteresis issue will be presented.
        Speaker: E. Todesco
      • 10:15
        What do we need to understand and optimize the LHC? 25m
        Can we monitor all the parameters relevant for machine performance (e.g. in terms of luminosity)? What can help us in pin-pointing the source of “non-confomities” (e.g. is it in the LHC, is it in the injectors”) What is missing? Do we have the tools required for data analysis and performance analysis? Fill-to-fill comparison, comparison with expectations Can data mining and correlation tools be enhanced (e.g. TIMBER?)? How?
        Speaker: O. Bruning
    • 10:40 11:00
      Coffee Break 20m
    • 11:00 13:20
      Session 3: Beam diagnostics and feedback systems

      Chair: Jörg Wenninger; Scientific Secretary: Reyes Alemany

      • 11:00
        Bunch by bunch beam instrumentation 30m
        This talk describes the LHC bunch by bunch beam instrumentation. The status of all the different systems are reviewed: Wire scanner, Synchrotron light monitor, Beam Position monitor, Schottky monitor, BCT, Wall current monitor, Longitudinal density monitors and Luminosity monitors. The achieved performances in 2010 and the already known limitations of both the hardware and the software will be discussed. The plans for upgrades in 2011 will finally be presented.
        Speaker: T. Lefevre
      • 11:30
        Feedbacks: status, operational dependencies and outlook for 2011 30m
        The tune measurement and FB saga. PLL as workhorse for 2011? FB and transverse FB. Q' FB - shall we modulate in every fill?  Orbit FB: improvements for 2011.
        Speaker: R. Steinhagen
      • 12:00
      • 12:20
        BPM: status, measurement reliability and outlook for 2011 20m
        This talk will present an overview of the performance of the LHC Beam Position System during 2010. Its dependence to beam intensity and surface rack temperature variations are discussed in more details. The modifications currently envisaged to improve the present system will be finally presented.
        Speaker: E. Calvo
      • 12:40
        Can we get a reliable on-line measurements of the transverse beam size? 20m
        The transverse beam emittances of the LHC proton and ion beams can be inferred by measuring the beam sizes with Wire Scanner (WS), Synchrotron Radiation (BSRT) and Beam Gas Ionization (BGI) monitors. This presentation covers all aspects related to the operation of such devices in 2010 with a particular emphasis on the monitors performance with respect to their design specifications and expected signals. The absolute and relative accuracy of the emittance measurement is discussed, including cross calibration among the three instruments and with the luminous region estimation during collisions at the LHC experiments. This allows reviewing the reliability of the on-line data and of the values published in the logging database. In addition, an overview of the programmed hardware and software upgrades is given.
        Speaker: F. Roncarolo
    • 13:20 14:00
      Lunch 40m
    • 14:00 16:00
      Session 4: Machine Protection systems

      Chair: Brennan Goddard; Scientific Secretary: Alick Macpherson

      • 14:00
        Do we understand everything about MP system response? 15m
        The presentation will give a brief overview on the performance of the machine protection system during the 2010 run with an emphasis on highlighting suspicious events which still need to be fully understood. Improvements and mitigations of potential holes in the protection systems will be discussed along with their impact on the 2011 run. A summary of the currently available tools and necessary improvements for the assessment of beam dump events will conclude the presentation.
        Speaker: M. Zerlauth
      • 14:15
        LBDS and abort gap cleaning 15m
        A number of possible failure scenarios and estimated occurrence were defined for the LHC Beam Dump System (LBDS). An analysis of the LIBDS performance during the first year of the LHC operation is presented and compared with respect to requirements and expectations. Several qualification tests have been regularly performed to assess the protection provided by the system in the eventuality of a failure. Possible hardware upgrades and improvements of machine protection test and operation procedures are explored. Abort gap cleaning deployment, related diagnostic and interlocking are discussed.
        Speaker: C. Bracco
      • 14:30
        How low can we go? Getting below 3.5 m b* 20m
        The LHC has made remarkable progress during 2010, fulfilling its ambitious goal for the year in terms of luminosity. For 2011, even higher performance has to be reached. One way of further increasing luminosity is to reduce the beam size at the interaction points, which is determined by the optical function beta∗. However, when beta∗ is decreased, so is the margin to the triplet aperture in terms of beam σ. This aperture must be protected from beam losses by the tertiary collimators (TCTs), which in turn have to be shadowed by other upstream collimators. This imposes a limit on the minimum achievable beta∗. In this talk, we discuss estimates of the available triplet aperture, the different margins required to guarantee protection (TCTs to aperture and TCTs to collimators in interaction region 6) as well as the conditions required for moving in collimators and protection devices further. All estimates of margins have to be based on assumptions on variations in central orbit and optical functions. Finally we conclude on the achievable beta∗ for different running scenarios and discuss the available margins during luminosity scans.
        Speaker: R. Bruce
      • 14:50
        Injection protection: are we taking it seriously, how can we make it safer? 20m
        The experience with the injection protection system during the 2010 run will be summarized, the setting-up times and stability will be evaluated. Weak points of the protections system at injection which became apparent with first high intensity experience will be discussed and solutions for 2011 presented if possible. The line between injection quality and injection protection issues will be emphasized and clarifying measures for the involved software tools to be implemented during the shutdown will be presented.
        Speaker: V. Kain
      • 15:10
        The human factor 20m
        The presentation will address the issues of the human risk factor for the machine protection and operation of the LHC and will highlight some of the key risk situations with examples taken from the 2010 run. Emphasis is placed on risk factors that are present in the current modus operandi as well as the foreseen improvements, both procedural and otherwise, that are intended to mitigate the risks in the 2011 run. A discussion on potential sources of human risk factors that lie outside the standard operations envelope and protective procedures will also be given.
        Speaker: A. Macpherson
      • 15:30
        General discussion 30m
    • 16:00 16:30
      Coffee Break 30m
    • 16:30 18:30
      Session 5: Beam losses

      Chair: Ralph Assmann. Scientific secretary: Stefano Redaelli

      • 16:30
        Multi-turn losses and cleaning 30m
        In the LHC all multi-turn losses should occur at the collimators in the cleaning insertions. The cleaning inefficiency (leakage rate) is the figure of merit to describe the performance. In combination with the quench limit of the superconductive magnets and the instantaneous life time of the beam this defines the cleaning dependent beam intensity limit of the LHC. In addition, limits can arise from radiation-induced effects, like radiation damage and radiation to electronics. In this paper the used collimator settings, the required setup time, the reliability of collimation (all multi-turn losses at collimators), and the achieved proton/ion cleaning inefficiency are discussed. Observed and expected losses are compared. The performance change during the months of operation is reviewed. In addition, the peak losses during high intensity runs, losses caused by instabilities, and the resulting beam life times are discussed. Taking the observations into account the intensity reach with collimation at 3.5 TeV is reviewed.
        Speaker: D. Wollmann
      • 17:00
        Injection/extraction losses 30m
        Single pass losses at injection into LHC and extraction to the beam dump are distinguished regarding their origin. Potential mitigations as increasing the opening of the injection protection devices or temporarily blinding the BLM system at injection are discussed. The limits for injecting higher intensities in 2011 due to losses above BLM thresholds together with the risk for quenching magnets or damaging devices are extrapolated from observed loss levels in 2010 operation.
        Speaker: W. Bartmann
      • 17:30
        Losses away from collimators: statistics and extrapolation 20m
        The Beam Loss Monitors (BLMs) in long straight sections and the dispersion suppressors being covered in the following talk, this presentation focuses on beam losses in the LHC arcs. The main task of the approximately 2200 arc monitors is quench prevention. The arcs are generally very well protected by the collimators. The aim of this talk is to search for possible holes in this protection, and to present the impact of short (single turn to several turn) and/or highly localized losses on the arcs. Among others, leakage from the collimation regions, losses originating from the interaction points and ‘UFO’ type loss have been analyzed. Possible limits in beam intensity and luminosity will be discussed. Furthermore, the requirements for BLM system tests following the interventions during the technical stop will be presented.
        Speaker: E.B. Holzer
      • 17:50
        BLM thresholds: limiting locations 20m
        Around 4000 Beam Loss Monitors are installed around the LHC ring and they must detect dangerous beam losses which could quench the superconducting magnets or damage components of the accelerator. The LHC BLM system was working very well during the 2009 and 2010 run. All dangerous beam losses have been detected by the system and the beam dump was always initiated correctly so that no damage or quench occurred. However a further fine-tuning of the beam abort thresholds is still needed, especially for the high luminosity and high beam intensity runs being planned for 2011. Possible sources and affects of a reduced signal to noise ratio of the beam loss monitors during the upcoming 2011 run will be addressed. Furthermore it will be verified if the specified beam loss rates can be achieved, at what locations we have possible limiting thresholds and to what extend an increase of the thresholds at what elements is needed. A special focus will be given on losses and thresholds at and around collimators, including also possible correlations between collimator movements, vacuum conditions and beam losses.
        Speaker: A. Nordt
      • 18:10
        General discussion 20m
    • 18:30 19:50
      Special Session

      Experiments, ATLAS, ALICE, CMS, LHCb

      • 18:30
        ATLAS: highlights from the first run 20m
        Speaker: Fabiola Gianotti
      • 18:50
        ALICE: The 2010 LHC Experience 20m
        Speakers: on behalf of Jurgen Schukraft , Riegler Werner
      • 19:10
        CMS 2010 and Prospects for 2011-12 20m
        Speakers: on behalf of Guido Tonelli , Tiziano Camporesi
      • 19:30
        Compliments to LHC from LHCb 20m
        Speaker: Golutvin Andrei
    • 20:00 22:00
      Dinner 2h
    • 09:00 11:00
      Session 6: Luminosity performance

      Chair: Malika Meddahi; Scientific Secretary: Verena Kain

      Discussion Summary
      • 09:00
        Longitudinal and transverse emittance preservation 20m
        The preservation of the transverse emittance is crucial for luminosity performance. At the LHC design stage the total allowed emittance increase was set to 7 % throughout the LHC cycle. The injection process is particularly critical in this respect. Results of an analysis quantifying the emittance increase from injection to stable beams will be presented. The luminosity goals of the 2010 proton run could be achieved with fewer bunches than initially foreseen. This is due to the excellent performance of the injectors concerning the higher than nominal number of protons per bunch and also the smaller than nominal emittances. Smaller emittances mean more energy density, possible machine protection concerns will be addressed in this presentation. Recommendations for required instrumentation and emittance preservation goals for next year’s run will be given.
        Speaker: V. Kain
      • 09:20
        LHC Beam-Beam 20m
        First experiences with colliding beams have been collected during the 2010 LHC run and some observations of beam-beam effects will be reported. The observations are interpreted and critically compared with the expectations and strategies proposed at the previous workshop. Based on the available information, possible limitations are evaluated and strategies for the optimization are derived.
        Speaker: W. Herr
      • 09:40
        Strategy for luminosity optimisation 20m
        Integrated luminosity is a key parameter for the performance of a particle collider and depends both on beam parameters and operational efficiency. The experimental detectors are turned on and start acquiring useful data only when the machine is declared as stable, it is therefore important to minimize the duration of the activities from the collapsing of the separation bumps until STABLE BEAM is declared. After a review of the current procedure and tools used to bring beams into collision and optimize luminosity, observations and lessons learnt during the 2010 proton run will be presented. The reproducibility and implication of the current procedure regarding machine protection and operation efficiency will be discussed based on this first experience.
        Speaker: S. White
      • 10:00
        The LHC optics in practice 20m
        During LHC 2010 run, approximately 40 experimental sessions for optics Measurements were carried out. Both local and global corrections were implemented demonstrating the feasibility of achieving 10% peak beta-beating. The long-term optics stability is presented with extrapolations of errors down to beta* of 0.55 m. Operational issues arising during corrections, as the treatment of hysteresis, will also be discussed.
        Speaker: R. Tomas
      • 10:20
        Hump: how did it impact the luminosity performance? 20m
        The status of the measurements performed to characterize and identify the origin of the so-called hump will be presented as well as its impact on beam performance and the countermeasures found to mitigate its effects. The directions for future investigations will be outlined.
        Speaker: G. Arduini
      • 10:40
        LHC Beam parameters: pushing the envelope? 20m
        The goal for 2011 is to deliver an integrated luminosity of one inverse femtobarn to the experiments. This will require to gain an order of magnitude in peak luminosity, i.e. run with values of more than 1E33 cm-2s-1, whereas a maximum of ~2.07E32 cm-2s-1 was achieved so far. Many collective effects were observed this year, first when the intensity per bunch was increased and subsequently when the number of bunches was pushed up and the bunch spacing was reduced. A critical review will be made to examine which parameters can be realistically used to increase the luminosity, analysing the risks and the consequences. A scenario is proposed as well as a back-up solution.
        Speaker: E. Metral
    • 11:00 11:30
      Coffee Break 30m
    • 11:30 13:00
      Session 7: Wrapping up

      Chair: Mike Lamont; Scientific Secretary: Malika Meddahi

      Discussion Summary
      • 11:30
        Parameters for 2011 - 2011 LHC beam operation plans (incl. intensity steps) 35m
        The assumed LHC beam parameters for 2011 are first summarised. The overview of the 2011 schedule is presented and includes hardware commissioning, beam re-commissioning, re-validation, scrubbing, technical stops, MD, ions and special physics run requests. A proposal is made for the strategy in intensity stepping up and potential issues are described together with possible actions. Finally, the potential peak and integrated luminosity are given
        Speaker: J. Wenninger
      • 12:05
        Workshop summary - strategy for beam commissioning in 2011 45m
        A very first attempt is made to synthesis the outcomes of the workshop. A list of issues and prioritized actions will be presented. With broad brush strokes, the beam commissioning strategy for 2011 will be outlined and the requirements the different teams involved will summarized.
        Speaker: M. Lamont
      • 12:50
        Closing remarks 10m
        Speaker: S. Myers
    • 13:00 13:30
      Finger food 30m
    • 13:30 13:35
      End of Workshop - Bus returns to CERN 5m