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LHC Performance Workshop - Chamonix 2009
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Le Majestic (Chamonix)
Le Majestic
Chamonix
Description
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DISCLAIMER
“The Chamonix workshop was an open exchange of views and opinions. All the presentations made at the workshop are available here. The views expressed in individual presentations do not necessarily represent those of the CERN management.”
DISCLAIMER
“The Chamonix workshop was an open exchange of views and opinions. All the presentations made at the workshop are available here. The views expressed in individual presentations do not necessarily represent those of the CERN management.”
The LHC Performance Workshop will take place from 2 to 6 February 2009 in the Centre de Congrès Le Majestic, Chamonix, France. Attendance is by invitation only.
The workshop will focus on the safe and reliable consolidation, re-commissioning and operation of the LHC.
| Steve Myers | Chairman |
| Roger Bailey | Deputy Chairman |
| Frank Zimmermann | Scientific Secretary |
| Christian Carli | Editor of the Proceedings |
| Tjitske Kehrer | Workshop Secretariat |
A summing up of the Workshop will take place at CERN on 24 February 2009 in the afternoon (Main Auditorium).
Map of Conference & Hotels situation
Support
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Session 01 - What did we learn without beam in 2008
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1
Training the dipolesDuring the hardware commissioning in 2008 more than 30 training quenches were performed in the main dipole circuits in sectors 45, 56, and 78. An overview of these quenches will be given, and the quench levels will be compared to the training observed in SM-18. Quench propagation to adjacent dipoles will be discussed, and an estimate will be given of the total number of training quenches required to reach 6, 6.5, and 7 TeV in all 8 sectors.Speaker: Arjan Verweij
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2
Electrical and calorimetric measurements and related software.During the incident of sector 3-4 on September 19th, the temperature of a number of magnets increased over the expected values prior to the circuit failure. A review of the data logged during powering tests on all circuits indicated potential resistive splices in sectors 1-2 and 6-7. Calorimetric and electrical measurements confirmed a high resistance in magnet B16.R1 and B32R6. Systematic measurements have been performed in other cold sectors of the LHC during which the temperature increase and voltage across magnets were acquired at different currents. Cryogenic subsectors on which the temperature increase was abnormal were equipped with precise voltmeters to detect eventual resistive splices in the bus-bars. The findings of the measurement campaign will be shown as well as the plans to implement similar diagnostics as a routine check prior to powering the superconducting circuits of the LHC.Speaker: Nuria Catalan Lasheras
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3
The Sector 3-4 IncidentIn the days following the incident which occurred in Sector 3-4 of the LHC, a Task Force was constituted by experts from the relevant LHC systems, with the mandate to establish the sequence of facts, based on experimental observations and measurements, to analyse and explain the development of events, in relation with design assumptions, manufacturing and test data and risk analyses performed, and to recommend preventive and corrective actions for Sector 3-4 and others. This is the report of the Task Force.Speaker: Philippe Lebrun
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11:35
coffee break
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4
Superconducting electrical circuitsDuring the almost 18 months of hardware commissioning nearly all superconducting circuits of the LHC were tested with success and many of them are/were ready for operation. However a number of unexpected observations were made, which either may limit the performance of the accelerator, have an impact on the operation, require additional hardware and software, or were simply a challenging puzzle without further impact.Speaker: Karl Hubert Mess
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5
LHC Cryogenics: What did we learn from cool-down to first beamsCool-down and refrigeration issues, cryogen management, Tuning LSS components, stability achieved, delays to recover failures, preliminary availability for beams, medium term consolidations envisaged.Speaker: Mr Serge CLAUDET
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6
What else did we learn?Differently from its definition, the Hardware Commissioning has required a massive support of Software applications, which had in turn to be commissioned. Apart the control applications and the communication systems, special software tools had to be developed to rapidly and smoothly allow a safe circuit commissioning (sequencer, post-mortem, circuit commissioning status,...). The first part of this talk will provide an overview of these instruments, focusing on their importance during circuit test and the experience gained on them. The second part will be devoted to the analysis of some "puzzlying and annoying" hardware problems that slowed down the commissioning and will possibly limit our test rate in 2009.Speaker: Mirko Pojer
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1
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16:30
Coffee break
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Session 02 - Safety
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7
Consequences for safety of personnel following S34Following the accident in Sector 34, some immediate and short term restrictions on personnel access have been put in place. Some restrictions on specific operations have also been decided. Some of these restrictions went much beyond the previously agreed rules for access and powering but have been decided by precaution pending further investigation of the event. In the light of lessons learnt from the S34 accident, I will review the access conditions in different parts of the LHC (surface, tunnel and service areas, experimental areas) and in various conditions of operation of the installation, taking into account the electrical and cryogenics risks as well as beam conditions. In a second part I will review some accident scenarios that have been or can be envisaged, and will assess for these cases the adequacy of the access and intervention rules presented before.Speaker: Ghislain Roy
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8
Safety OrganisationSafety has been an integral part both for the installation and hardware commissioning phases of the LHC The objective of this presentation will be to out line the new structure that is in place, the general organization, introduce the key players, provide an insight into the safety documentation that is available to help everyone, explain what is required to carry out any form of intervention in the underground areas and provide feed back on our strong and weak points.Speakers: John Robert Etheridge, Rudiger Schmidt
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9
Access & LACS/LASSThe LHC access system has been progressively put in operation starting from Spring 2008 and has been used in different configurations during the LHC commissioning phases (powering tests, beam operation and shut-down). Based on the experience gained during these phases, several modifications have been requested for improving personal safety as well as operational efficiency for the next run. The performances and issues of the LACS/LASS found during the first year of operation will be presented. The status of the implementation for a more efficient operation in 2009 will then be reviewed. In preparation of the re-powering of part of the machine combined in parallel with accesses, possible interlocking of the access system with other equipments (i.e power converter, PIC...) will be finally discussed.Speaker: Laurette Ponce (Unknown)
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10
Safety systems (AL3) and systems relevant to SafetyThe AL3 systems are basic life protection and are especially important during the shutdown; there should be no point in the LHC underground areas in which a person is not or cannot be informed of the dangers around him when they exist and so take appropriate action. The implantation of the different detection and alarm systems will be reviewed and their performance and reliability examined. The need for fire doors to control released Helium will also be considered, which may have consequences for the ventilation and access systems.Speaker: Steve Hutchins
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11
Possible scenarios for a safety upgrade of the ventilation systemThis paper/presentation describes the existing LHC ventilation (HVAC) system, the design principle followed for the LEP Project and the modifications implemented for the LHC Project. A discussion on possible referential standards to compare the existing system with is presented and possible axes for its improvement, based on these referentials, are discussed. Finally, some recommendations are given based on the system's present capabilities and the estimated investment necessary to achieve compliance to the referentials chosen.Speaker: Joaquin Inigo-Golfin
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12
Emergency preparednessOn September 19th 2008, a technical fault was at the centre of a sequence of events which hampered the performance of certain equipments of the LHC 3-4 sector. Once the first effects of this sequence of events were detected, the behaviour of the CERN staff confronted to this complex and critical situation became the centre of the risk control process. During such a downward spiral the preparation of all stakeholders is essential and should respect the (apparently) basic principles of emergency preparedness. Preparedness towards normal operation of CERN facilities towards minor up to major emergency situations will be presented. The main technical, organisational and legal frameworks of the CERN emergency preparedness will be recalled, highlighting the CERN risk management and risk control strategy. Then, the sequence of events experienced by different stakeholders on September 19th will be reported, thus starting the learned lessons process.Speaker: Enrico Cennini
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7
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Session 03 - Repair of 34
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Magnets repair for 3-4 sectorsThe incident in 3-4 sector has affected some 50 main LHC magnets. Such a scenario was never considered as realistic in the past. Our reserve of magnet has been barely sufficient (some 40 dipoles and 14 SSS, in some cases the reserve magnet types are not compatible with the one damaged). Furthermore the subsequent measurements on other sectors have shown the necessity to replace other magnets. The plan and methods for assessing the damage that occurred to a cold mass and the decision on its substitution, rather than a simple revamping of the magnet itself, will be discussed. The question if the magnets in the sector are adequate for powering and beam operation will be addressed. The implementation of the changes and their traceability will be presented. Finally the spare situation, which includes the plan for repairing and testing of all damaged cold masses of sector 3-4 and the impact on it of the 3-4 incident, is discussed.Speaker: Lucio Rossi
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14
Reinstallation and interconnectionsReinstallation of the first magnets in the D-zone has already started in parallel with the removal of damaged magnets. It is planned for the last magnets to be reinstalled by end March. The start of interconnection (IC) work requires a minimum chain of adjacent magnets and their alignment: it is planned to start this in late February. IC work will now be performed by CERN and FSU staff, no longer with the Main Contractor as for past series work. The status of the IC situation, the new work organization and responsibilities will be presented. Quality Control issues are particularly important, both in order to reproduce past quality in the new conditions, and of course to improve on critical aspects. IC work will also continue in parallel outside the D-zone in 34 and in other sectors during the shutdown. The issues of resources and scheduling are addressed.Speaker: Francesco Bertinelli
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15
Vacuum system – how to get ready for beam ?During the incident of sector 3-4, the two beam vacuum sectors of 2.8 km each and four insulation vacuum sectors i.e. 750 m were vented to atmospheric pressure. Besides the mechanical damages of the nested bellows and plug-in-modules due to the mouvement of the cold masses under the helium pressure, soot and debris of superinsulation were spread inside the beam and insulation vacua. The presentation will cover the extend of the damage from Q6R3 till Q6L4. The strategy deployed to repair, to clean and to qualify the damaged vacuum systems will be discussed. Scheduling and compatibilty with beam operation issues will be also adressed.Speaker: Dr Vincent Baglin
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10:20
Coffee break
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16
Other systems – what needs to be done? Repair and reinstallation of other systems (standard QPS, PC, BLM, Cryo, Survey, …)After the incident occurred on the 19th September all equipment and systems (such as QPS racks, PC, BLM, Cryo instrumentation control etc.) located in the tunnel, especially in the incident affected area, were removed from the tunnel in order to allow an easy damage inspection. After a change or repair, during the re-installation phase, all these equipments will be put back in the tunnel and re-tested once connected to the others. In this paper we point out what are the needs of every system (and infrastructure: ventilation, civil engineering, control network...) and the activities to be done in order to avoid interference, facilitate and optimize the process of re-commissioning of the Sector 34.Speaker: Solfaroli Camillocci Matteo
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17
Consolidation after beam operation – constraints from radiation protection considerationsSince 10th September 2008 a major part of the LHC installation is classified as Supervised Radiation Area. As soon as LHC operation will be resumed in 2009, beam losses will inevitably increase the activation of accelerator and detector components, the maintenance and repair teams of the accelerator and the detectors risk to be exposed to elevated radiation levels. To reduce dose to personnel consolidation and repair work should preferably be done during the present shut-down. The radiological impact of delayed consolidation and the consequences for repair in case of future incidents will be presented.Speaker: Doris Forkel-Wirth
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13
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16:30
Coffee break
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Session 04 - Strategy for consolidation to avoid incident and limit collateral damage
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Insulation vacuum and beam vacuum overpressure releaseThere is evidence that the incident of 19th September caused a high pressure build-up inside the cryostat insulation vacuum which the existing overpressure devices could not contain. As a result, high longitudinal forces acting on the insulation vacuum barriers developed and broke the floor and the floor fixations of the SSS with vacuum barriers. The consequent large longitudinal displacements of the SSS damaged chains of adjacent dipole cryo-magnets. Estimates of the helium mass flow and the pressure build- up experienced in the incident are presented together with the pressure build-up for an even more hazardous event, the Maximum Credible Incident (MCI). The strategy of limiting the maximum pressure by the installation of addition pressure relieve devices is presented and discussed. Both beam vacuum lines were ruptured during the incident in sector 3-4 giving rise to both mechanical damage and pollution of the system. The sequence, causes and effects of this damage will be briefly reviewed. We will then analyse possible actions that could be taken to minimize the impact of a similar incident on the operation of the LHC.Speaker: Vittorio Parma
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19
Improved anchoring of SSS with vacuum barrier to avoid displacementAs presented in the previous speech, the incident in sector 3-4 of the LHC caused a high pressure build-up inside the cryostat insulation vacuum resulting in high longitudinal forces acting on the insulation vacuum barriers. This resulted in braking floor and floor fixations of the SSS with vacuum barrier. The strategy of improving anchoring of SSS with vacuum barrier to avoid displacement is presented and discussed.Speaker: Ofelia Capatina
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20
Bus bar joints stability and protectionA defective bus connection between two dipole magnets was the primary cause of the incident in sector 34 on September 19th. I will show how this could have happened, i.e. how a highly resistive joint has caused a thermal runaway and burned (or opened) before the QPS threshold was reached. In the second part of the talk I will present the new detection limits for the QPS upgrade of the RB and RQ circuits, required to avoid similar thermal runaways in the future.Speaker: Arjan Verweij
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21
QPS Upgrade and Re-commissioningPrior to the re-start of the Large Hadron Collider LHC in 2009 the protection system for superconducting devices QPS will be submitted to a substantial upgrade. The foreseen modifications will enhance the capability of the system in detecting problems related to the electrical interconnections between superconducting magnets as well as the detection of so-called aperture symmetric quenches in the LHC main magnets. The presentation will describe the design and implementation of the new protection layers and report on recent tests with prototype devices. It will address as well the planned steps for commissioning of the new system, possible limitations and the additional tools and procedures required to make use of its full capability. Finally the recent progress with respect to procurement, production, test and installation will be presented.Speaker: Reiner Denz
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22
Risk Analysis for the Different Consolidation ProposalsIn parallel with the repairs in sector 34, improvements are planned to a number of systems, to allow safe detection of faults similar to the one which caused the incident of 19 September, and to limit the damage should a similar incident nonetheless occur. These include improved bus and quench detection systems, improved pressure relief for the insulating and beam vacuum systems, and improved anchoring of the SSS to the tunnel floor. Not all of the planned mitigations, however, may be fully implemented before the restart of the LHC in 2009. I will review the potential benefits of partial or complete implementation of each of the planned improvements, individually or together with others, and conversely the potential risks (consequences) of delayed implementation. I will also review the risks that remain even after the planned consolidation is complete. Considering all proposals and the different risks, I will comment on what would be the best strategy for consolidation, and on the strategy for operations under different consolidation scenarios.Speaker: Jim Strait
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18
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Session 05 - Shutdown Modifications 2008/9 and Future shutdowns
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23
Where are we with the current shutdown?The first shutdown of the LHC machine started on the 17th of November 2008. In addition to typical shut-down interventions and the works already foreseen (e.g. phase 1 collimator installation), some additional consolidation work is needed. On top of this comes the work caused by the 19 September incident and the subsequent tests carried out in November and December. This talk will give an overview of the activities currently planned and the key drivers for overall length of the shutdown, highlighting the critical points.Speakers: Julie Coupard, Katy Foraz
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24
Alternative scenarios for the current shutdownAlternative options for the current shutdown will be presented. These options include warming up additional sectors to complete the consolidation activities. The potential impact of these revised schedules on the beam schedule in 2009, as well as the length and timing of the following shutdown will also be presented.Speakers: Julie Coupard, Katy Foraz
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25
Running through the winter 2009/10? Is it just a cost issue?As a complement to the previous talk, a number of questions, that will need to be addressed in order to consider LHC beam operation over the winter 2009-10, will be raised.Speaker: Mario Batz
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26
How do we keep track of upgrades / changes?Layout and electrical circuits of the LHC machine are well documented in the databases and the data has been used throughout hardware and beam commissioning. During the shutdown a number of changes will be made all around the accelerator, to different systems. The presentation will address in what areas changes are expected and how the changes are (or are not) documented. Proposals will be made how to record and track the changes in order to avoid to use data that does not correspond to the as-built status when restarting the machine in Spring.Speaker: Rüdiger Schmidt
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10:10
coffee break
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27
Consequences of warm-up of a sector above 80KThere may be circumstances when a sector has to be partially or totally warmed-up to temperatures above 80 K, that is when thermal dilatation starts to play a role. Some equipment have been identify as presenting a risk, like the non-conform "plug-in" modules in the arcs. Because of motion induced by thermal dilatation, the electrical (ElQA) quality control may also have to be done again after cool-down. The main reason identified so far for partial warm-up is the required maintenance of the cooling towers and the cryogenics plants. There is also the request from the vacuum group to periodically warm-up the beam screen to temperatures in the 100 K region to release and pump-out the gas crysorbed on the surface of the beam screen. Observed and expected temperature conditions and statistics on failures of PIMs in sectors which have been warmed-up will be presented in this contribution. Methods to detect buckled PIMs will be described, as well as a recommended strategy for consolidation. Finally, the required electrical quality controls will also be described.Speaker: Pierre Strubin
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28
Critical sparesFollowing the completion of the installation last year, several reviews (ATC, LTC, MARIC) were carried-out to draw up the inventory of the spare LHC components. A detailed summary of these exercises will be given and the present situation with the spares following the September 19th incident will be presented.Speaker: Roberto Saban
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23
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16:30
Coffee break
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Session 06 - What else can go wrong
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Maximum Credible IncidentsFollowing the incident in sector 34, considerable effort has been made to improve the systems for detecting similar faults and to improve the safety systems to limit the damage if a similar incident should occur. Nevertheless, even after the consolidation and repairs are completed, other faults may still occur in the superconducting magnet systems, which could result in damage to the LHC. Such faults include both direct failures of a particular component or system, or an incorrect response to a “normal” upset condition, for example a quench. I will review a range of faults which could be reasonably expected to occur in the superconducting magnet systems, and which could result in substantial damage and down-time to the LHC. I will evaluate the probability and the consequences of such faults, and suggest what mitigations, if any, are possible to protect against each.Speaker: Jim Strait
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30
Risks due to UPS malfunctioningTo ensure the safety of the LHC in case of partial or general electrical power failure, all components of the machine protection system are powered by an Uninterruptable Power Supply (UPS). However, just as for other systems of the machine, the UPS itself is not immune to malfunction. This presentation will evaluate the impact of a UPS malfunction on the operation of the machine protection system and the consequences for the protection of the machine.Speaker: Thiesen Hugues
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31
Impact of SEUsRadiation levels expected in various LHC alcoves and more precisely the integrated flux of high-energy hadrons (multi-MeV range) pose a significant risk to any electronics not specifically designed or tested for such radiation levels. Different electronics and their expected overall radiation sensitivity are discussed. Equipment is further grouped in terms of criticality for both, machine safety and operation efficiency. The findings are put in relation with the radiation levels based on Monte-Carlo calculations and expected in the LHC tunnel and alcoves. Equipment partly depends on other devices and installations (e.g., communication) thus weak links are identified and redundancy issues are discussed. Areas are prioritized not only by expected radiation levels but also by carefully considering respective equipment details. Long-term development of radiation hard equipment is understood to be indispensible and the importance to efficiently and effectively steer SEU related activities is underlined.Speaker: Markus Brugger
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32
Beam induced damage - what is a safe beam?The knowledge of damage levels is vital to define protection schemes, beam loss monitor thresholds, safe beam limits for setting up the machines, etc. This talk will try to revisit our present knowledge and assumptions on damage levels in the LHC in terms of lost beam intensity, beam momentum and emittance. It is clear that with the LHC’s unprecedented energy reach, benchmark tests to cross-check energy deposition simulations for all possible energies before LHC start-up have not been possible. Also, the definition of when equipment is damaged is not always straight forward. In view of the obvious limitations to our knowledge of damage levels, operational commissioning and LHC running strategies will be re-discussed, open questions will be highlighted and proposals will be presented where possible.Speaker: Verena Kain
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33
Worst case beam incident causes and protectionThe failure events which can occur with the fastest timescales in the LHC are mainly associated with the injection and extraction processes. The possible worst-case failure events are catalogued and the protection layers in place to prevent the failure or mitigate the consequences are described. Particular attention is paid to the beam dump system kickers, the energy tracking system, the injection kickers and the aperture/tune kickers. The requirements for the positioning of the dedicated absorbers with respect to the aperture will be recalled, and the implications for the setting-up and operational stability critically examined.Speaker: Brennan Goddard
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34
Weaknesses of the MPSThis report tries to solve an unsolvable problem: to foresee problems or incidents in the operation of the LHC that are not covered by the machine protection or beam interlock systems. It is evident that this task is not easy to fulfil but nevertheless what still can be done is to scrutinise the logic of the LHC machine protection system and to compare its structure with “unexpected” incidents that occurred in other large storage rings. Going through the history of these rings and mainly profiting from discussions with the experts, this contribution summarises events that are normally not published in conference reports, sometimes they are not even mentioned in internal papers. By the definition of the subject this reflection cannot be complete but there is hope that it will enlighten topics and failure scenarios that are worth to be considered in the LHC operation.Speaker: Bernhard Holzer
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21:00
Restaurant La Caleche
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29
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Session 07 - What did we learn with beam in 2008?
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Injection TestsThe success of the start-up of the LHC on 10th of September was in part due to the preparation without beam and injection tests in 2008. The injection tests allowed debugging and improvement in appropriate portions to allow safe, efficient and state-of-the-art commissioning later on. The usefulness of such an approach for a successful start-up becomes obvious when looking at the problems we encountered before and during the injection tests and could solve during this period. The outline of the preparation and highlights of the different injection tests will be presented and the excellent performance of many tools discussed. A list of shortcomings will follow, leading to some planning for the preparation of the run in 2009.Speaker: Verena Kain
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36
Operational experience with circulating beamFollowing various injection tests, the full LHC beam commissioning started on September 10th. Within three days of beam operation, we established stable and captured circulating beam 2 and achieved circulating beam 1 for many turns. This was made possible by a thorough preparations of all the required accelerator systems, beam instrumentation and control software, which all achieved a remarkable performance. First beam measurements of the linear machine optics were commissioned and showed that the machine optics is well under control. The operational experience with circulating beam, the performance of the various systems and the first measurement results are reviewed. The commissioning procedures for the various systems are presented and lessons learnt for the 2009 operation are discussed.Speaker: Stefano Redaelli
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37
Beam-based measurementsThe constraints in the LHC machine protection impose tighter optics tolerances than in any other hadron collider. A variety of beam-based measurements in the first days of LHC operation was effective to measure aperture clearance, magnet polarities and machine optics. A summary of these measurements is given together with model insights.Speaker: Rogelio Tomas
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38
Transfer lines and Injection: results from machine studies during beam commissioningBeam commissioning of the SPS to LHC transfer lines performed during the summer 2008 is reported. The emphasis is put on the optical checks measured for the first time in the last part of the lines and into the LHC. In particular, extensive trajectory studies, dispersion measurements and coupling analysis are discussed. These studies were conducted in parallel with hardware checks and the outcome is summarised.Speaker: Malika Meddahi
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10:10
Coffee break
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39
Injection and beam dumpThe initial commissioning of the LHC injections and beam dumps allowed the basic functionality of the systems to be verified, together with progress to be made on some of the systematic checks and measurements foreseen in the detailed commissioning programme. The observations and measurement results are summarised, including comparisons of element strengths and synchronisation, details of the local aperture measurements and some performance data for specific equipment sub-systems. The lessons learnt for the future LHC commissioning are emphasised.Speaker: Brennan Goddard
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40
First Results from the LHC Beam Instrumentation SystemsDuring the 2008 LHC injection synchronisation tests and the subsequent days with circualting beam, the majority of the LHC beam instrumentation systems were capable of measuring their first beam parameters. This included the two large, distributed, beam position and beam loss systems, as well as the scitillating and OTR screen systems, the fast and DC beam current transformer systems, the tune measurement system and the wire scanner system. The fast timing system was also extensively used to synchronise most of this instrumentation. This presentation will comment on the results to date, some of the problems observed and the improvements to be implemented before the next LHC run.Speaker: Rhodri Jones
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41
Controls & softwareA large number of components of the LHC controls infrastructure have been intensively exercised during several dry runs and the injection synchronization tests in 2008, in preparation for the LHC start up with beam. All the prior tests were extremely useful to validate the basic functionality, to identify areas of weakness and to prepare the controls to a stable and well functioning infrastructure, which supported the successful LHC start up. This presentation will summarize the outcome of the controls commissioning with emphasis on major components like LSA, Timing synchronization, middleware, logging, and Role Based Access, the issues observed and the improvements to be implemented before the next LHC run in 2009.Speaker: Eugenia Hatziangeli
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42
First Field Test of FiDeL, the Magnetic Field Description for the LHCThe start-up of the LHC has provided the first field test for the concept, functionality and accuracy of FiDeL, the Field Description for the LHC. FiDeL is primarily a parametric model of the transfer function of the main field integrals generated by the series of magnets in the LHC powering circuits, from main optical elements to high-order harmonic correctors, both superconducting and normal-conducting magnets. In addition, the same framework is used to predict harmonic errors of both static and dynamic nature, and forecast appropriate corrections. In this paper we give a description of the level of detail achieved in the model and the rationale adopted for the LHC start-up. Beam-based measurements have been used for an assessment of the first-shot accuracy in the prediction of the current setting for the main arc magnets. We finally give a list of priority issues to be addressed, and sketch a plan for the preparation of the LHC restart.Speaker: Luca Bottura
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35
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16:30
Coffee break
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Session 08 - What we will do for beam preparation in 2009
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43
Magnet CircuitsThe LHC has 1572 superconducting circuits. Most of the time and resources during the Hardware Commissioning were consumed by tests of each circuit of the collider, the so-called powering tests. The tests consisted in carrying out several powering cycles at different current levels for each superconducting circuit. The number of tests needed for each sector was around 1500, thus more than 12000 for the whole machine. The aim for the 2009 campaign is to minimise the total time needed for re-commissioning these circuits before beam operation at 5 TeV. This will be done by reducing the number of steps needed for those circuits which have been already commissioned in a similar way as it was done for the second commissioning campaign in sector 4-5 and by optimising the test planning and execution applying the huge experience gathered in the last two years of powering tests. The special powering plan designed for sector 3-4 and the commissioning of the new systems such as the QPS upgrade are also presented.Speaker: Antonio Vergara Fernandez
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44
Powering InterlocksThe powering interlock systems for sc and nc magnets have been fully validated during HWC 2008. The presentation will summarise the changes and new functionalities that will be applied to the two interlock systems during the shut down and their impact on future re-commissioning. Improvements expected for the commissioning tools will be summarised, including time estimates and scheduling issues for HWC and beam commissioning 2009.Speaker: Markus Zerlauth
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45
Beam InterlocksA large fraction of the MPS was commissioned in 2008 in view of the first LHC run, and first attempts to automate test sequences were implemented. This presentation will present the commissioning plans for the MPS system in 2009 based on the 2008 experience. A possible planning of the tests will be presented, including time estimates, scheduling issues and compatibility with HWC. Controls requirements will be outlined. MPS tests with beam will be discussed.Speaker: Jorg Wenninger
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46
Injection and Beam DumpThe hardware changes and maintenance actions on the LHC injection and beam dumping systems will be presented. The requirements for equipment tests, hardware commissioning and machine check-out will be given, highlighting the dependence and the impact on other interfaced LHC equipment.Speaker: Jan Uythoven
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47
RF Preparation for Beam in 2009Modifications to the ACS cavity tuning systems should be completed early in 2009. First tests on the power and low level RF systems will be done with waveguide shorts, as the cavities will be warm and the RUX45 tunnel roof blocks will still be open to allow transport of quadrupoles into sector 3-4. Any co-activity with magnet transport will need to be avoided till the installation of sector 3-4 is completed. Well before beam, the cavities will need to be cooled down and tuning and calibration checked. A period of cavity conditioning will certainly also be required. After cavity conditioning there will be a final check on the cavity tuning and RF feedback systems. These activities all require availability of 4.5 K cryogenics, in sectors 3-4 and 4-5. The beam control systems in UX45 will also be checked as far as possible before beam, together with remote controls and signal monitoring systems. A description of this work, the times needed for the various activities and a planning will be presented. Work on the ADT systems will be carried out in parallel.Speaker: Edmond Ciapala (CERN)
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48
SC Magnet (re)trainingWe will give an overview of the training of all the LHC superconducting magnets based on the experience acquired diring the hardware commissioning. Using this information and the data relative to the test of individual magnets during manufacturing, we will give a view on the expected requirements for the training at 5 and 7 TeV.Speaker: Ezio Todesco
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43
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20:00
Cocktail - Mercure
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Session 09 - What will we do with beam in 2009/10
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49
Experiments desiderataIn this talk, an attempt will be made to review the LHC experiments desiderata in the current LHC context. The impact on the physics program of the beam energy and integrated luminosity shall be reminded. In particular, the benefits and shortcomings will be presented of a 900 GeV run and of a pilot run at a yet to be defined higher energy. A few run scenari for 2009 (and 2010) will be sketched.Speaker: Massimiliano Ferro-Luzzi
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50
Options and preferences for proton runningThe choice of parameters for proton operation in the LHC in 2009 is subject to constraints from beam dynamics as well as the experiments desiderata. These constraints are reviewed and the preferred operational scenarios are presented together with possible strategies to increase the performance.Speaker: Werner Herr
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51
Ions in the LHCThe LHC should make a “hot switch” from colliding protons to colliding lead nuclei in order to maximize the physics yield in a limited running time. I shall describe how we plan to achieve this and review the pre-conditions including the readiness of the RF system and beam instrumentation. The initial run should have the beam structure foreseen in the “Early beam” parameter list but the collision optics and beam energy may be different, depending on what has been achieved in proton operation. I shall show how the performance, including luminosity and lifetime, depends on these variables and discuss possible operating energies.Speaker: John Jowett
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10:00
Coffee break
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52
Readiness of and plans for the injectors for 2009A large diversity of beams have been prepared in the LHC injectors in the past few years, such as single-bunch and multi-bunch beams, with 25 ns and 75 ns bunch spacings. In 2008 the efforts were mainly devoted to the revival of the multi-bunch beam with 50 ns bunch spacing, and the production of the different beams with intermediate intensities per bunch. The purpose of the present paper is twofold: firstly, review the status of the proton beams in all their forms, which could be delivered by the injectors in 2009 on request from the LHC; secondly, summarize the situation with the ions and in particular the SPS commissioning with the early ion beam, which took place at the end of the 2007 run.Speaker: Elias Metral
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Are we ready for the 2009 beam operation?In preparation for the 2008 LHC beam operation, commissioning procedures were established by the commissioning team to safely bring up the LHC performance from the initial beam tests to the first 7 TeV physics runs with reduced intensity and intermediate beta* values. The status of the procedures and their usage during the 2008 beam experience is reviewed. The improvements needed for the 2009 operation, in particular as far as the squeeze, luminosity performance, backgrounds and operating at reduced beam energies are concerned, are discussed. Requirements for ion operation are also presented.Speaker: Stefano Redaelli
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OrganizationThe organization and the structure put in place for the machine check-out and for the beam commissioning have been instrumental for the rapid progress of the commissioning of the LHC Machine before the Sector 34 incident. After a review of the 2008 experience, the organization for the 2009 will be sketched with the expected commissioning steps and the roles of the different actors. The issue of the organization during unplanned machine stops and their possible use for superconducting magnet training and interlock testing for operation at higher energy/intensity will be briefly discussed.Speaker: Gianluigi Arduini
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12:00
Lunch Mercure
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