Workshop Chamonix XIV

17 Jan 2005, 08:30 → 21 Jan 2005, 18:00 Europe/Zurich

503/1-001 - Council Chamber (CERN)

Second LHC Project Workshop. The workshop is focused on the performance and operation of the LHC as well as the construction, installation and commissioning of the project. Chairman Steve Myers Scientific secretary & editor of the proceedings John Poole Secretariat of the workshop Tjitske Kehrer Attendance is by invitation only. A summing-up covering the whole week will take place on Wednesday 2 February 2005 at 14:00 in the Main Auditorium (and not on 28 January 2005 as earlier announced).

Monday 17 January

Welcome Address by S. Myers

Session 1 - Beam Commissioning

Conveners: Eugenia (Scientific Secretary) Hatziangeli (AB-CO), Mike (Chairman) Lamont (AB-OP)

1 Overall Beam Commissioning Strategy

Effective commissioning of the LHC with beam will demand very good preparation; all concerned subsystems will need to be well-prepared and thoroughly tested before first beam. To clarify the demands on the systems involved the objectives of the commissioning phases are presented, along with an breakdown of the phases and the essential prerequisites for each. The nature of the interdependencies between the various systems is highlighted; in particular the need for a well-planned commissioning of the machine protection system.

Speaker: Mike Lamont (LFC)

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2 Transfer and Injection

Based on the TI8 experience, the measures neeeded to reach the required state of readiness of TI 2 and TI 8 to deliver beam to the LHC during the commissioning phase are discussed. The main objectives for the performance of the transfer lines and injections at this stage of the LHC commissioning are outlined, and the impact of the lower demanded intensities on equipment and machine protection commissioning is addressed. The procedures for commissioning the first injection in the LHC are described. Subsystem dependencies – radiation, instrumentation, controls – and the necessary pre-testing phases with beam are highlighted.

Speaker: Dr Brennan Goddard (CERN)

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3 450 GeV

The objectives of this phase are enumerated. The key prerequisites for establishing circulating beam and the procedures involved are detailed. Given circulating beam,the essential checks, measurements and associated procedures are clearly established. The time required for, and the scheduling of, subsystem commissioning is discussed. The importance of injection scheduling, synchronisation and controls is emphasized along with the need for thorough pre-testing.

Speaker: Dr Paul Collier (CERN)

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10:30 Coffee break

Coffee break

4 Ramping & Snapback

The procedure for ramping the LHC is clearly defined with particular attention to power converters, RF and controls. The necessary pre-testing of all systems is detailed. Snapback will pose a challenge and the strategy for dealing with it during initial beam commissioning is revisited. Measurements and system commissioning to be performed during the ramp commissioning phase are detailed. The demands on key subsystems such as feedback, RMS and instrumentation are stated.

Speaker: Dr Andrew Butterworth (CERN)

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5 Squeeze

The procedure for squeezing the LHC is defined with attention to the squeeze duration, the variation in magnet currents and the resulting limitations. The potential variation in key beam parameters is quantified. The demands on essential sub-systems [feedback, instrumentation and controls] are made clear. The requisite movement of the collimators and TCDQ during the squeeze are detailed.

Speaker: Oliver BRÜNING (CERN)

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6 BDI

It is clear that proper functioning of the beam instrumentation is vital to effective commissioning. How the key instrumentation is to be commissioned is described including a description of measurements and tests to be perform with beam during the various commissioning phases. The demands on other systems [controls] are clearly stipulated. The procedures to be followed to ensure proper preparation and pre-testing are also outlined.

Speaker: Hermann Schmickler (CERN)

slides  hope it works

Session 2 - Scheduling LHC Operation

Conveners: Paul (Scientific Secretary) Collier (AB-OP), Roger (Chairman) Bailey (AB-OP)

7 Introduction to Scheduling LHC Operation

In the first years of LHC running, several different modes of operation will have to be accommodated. As an introduction to the session on scheduling, the proposal for early proton running will be outlined, the first ideas for the breakdown of a year will be recalled, and a possible timeline for the first few years will be presented.

Speaker: Dr Roger Bailey (CERN)

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8 Machine checkout and setup periods

Before the first LHC beam operation and following the LHC hardware commissioning a cold checkout period is required to check the simultaneous functioning of the various LHC subsystem in their final configuration. Following this cold checkout period a set-up period with beam is required to verify the proper operation of all equipment, including the machine protection system, with beam. The tests required in both phases and the estimated overall time necessary to perform these tests is described. The same estimate is also made for the subsequent years of LHC operation.

Speaker: Dr Jan Uythoven (CERN)

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9 LHC Scrubbing Runs

To achieve its nominal performances, the LHC relies on the scrubbing runs to both improve the dynamic vacuum (beam lifetime) by a vacuum cleaning effect and decrease the electron cloud induced limitations (heat load and beam instabilities) by a beam conditioning effect. An optimum scrubbing run scenario will be presented based on the vacuum cleaning and beam conditioning results in the SPS together with their applicability to the LHC and in particular for the role played by the physisorbed gasses and the magnetic fields. The interdependence of the scrubbing run scenario with the beam parameters used during the first 3 years of operation will be presented and the limitations discussed, in particular the advantages and drawbacks of scrubbing runs at injection energy. The implications of the deconditioning effect observed when the machine is not operated with beams will be presented together with the consequences of a partial warming up of the cold parts during the shutdown. To follow the evolution of the vacuum cleaning and beam conditioning during the scrubbing runs, diagnostics are foreseen in the RT and Cold vacuum pilot sectors in IR4. These diagnostics will be specifically design and operated to provide information on the beam conditioning levels of the RT and colds sections of the LHC.

Speaker: Dr Jose Miguel Jimenez (CERN)

Slides Slides

10 Access System and its impact on LHC operation

The LHC access system is the outer safety shell of the LHC underground instalations and can help (hopefully not hinder) the smooth operation of the LHC First a description of the accessible parts of the installations in different modes (beam, shutdown, short access...) and what areas of the machine will or will not be accessible for regular maintenance (scheduled or not) and quick fixes will be presented. The sectorisation of interlocked areas and its impact on operation including patrols will be explained. The number of interlock points and some details about the most important ones will be detailed, with a view on the layout of the safety console in the CCC. Certain failure scenarios and the recovery paths can be presented based on our knowledge of the system under construction and on experience with previous machines. A first discussion on training requirements and authorization lists and organization will be presented. The interaction with experiments will also be addressed from a setorisation and responsibility point of view.

Speaker: Dr Ghislain Roy (CERN - AB DEPARTMENT)

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15:20 Coffee break

Coffee break

11 LHC Equipment Maintenance Policy and Requirements.

In view of the very complex equipment making up the LHC machine and its many ancillary subsystems, equipment maintenance policies will play a primordial role to ensure an optimal availability. As access to most of the machine systems is strictly regulated, maintenance interventions will require global co-ordination and collaboration from both CERN equipment groups and industrial support teams. The talk will briefly touch on the different main systems and technical infrastructure involved and what is presently known about their operations and maintenance policy. Further extensions to the LHC QAP on the operations and maintenance phase will be mentioned. Issues like mean-time to repair, spares and contractual piquet service will become of major importance already in the installation phase. A rapid introduction and some examples from CERN’s asset tracking and maintenance system (MP5) will show what support can be expected from an industrial approach to maintenance issues."

Speaker: Thomas pettersson (TS/CSE)

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12 Experiments’ desires and constraints during the early LHC operation

The experiments’ requirements for the initial commissioning of the detectors, like single beams and early collisions, will be addressed as well as the annual shutdown requests. Special needs, like the polarity switching of the LHCb and ALICE dipoles, will also be mentioned. The experiments’ requests for the Pb82 runs and special proton runs will be discussed. Possible special runs for the new LHCf experiment will be briefly mentioned.

Speaker: Dr Daniela Macina (CERN)

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13 LHC Operation with Heavy Ions

Pre-requisites for switching from p-p to Pb-Pb operation of the LHC (optics,controls, vacuum, instrumentation, etc.). Plan for commissioning the main rings with lead ions. Differences from p-p operation (RF, vacuum requirements, beam instrumentation, separation and optics in collision). Evolution of beam intensity,emittance and luminosity; effect of vacuum, the number of experiments illuminated, length of fills and any reduction in beam energy. Elucidation of performance limits (quenches from Pb81+, collimation) in the "Early Ion Scheme" and evolution to nominal luminosity.

Speaker: Dr John Jowett (CERN)

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14 Operation for TOTEM

The TOTEM experiment requires special running conditions in terms of beams, optics and stability around IR5.In addition TOTEM requests short one day runs at regular time intervals. Similar requirements apply to luminosity measurement runs at IR1. Dedicated time will have to be devoted to the commissioning of the TOTEM machine cycle and for each run, additional setup time must be foreseen for machine and optics checkout. Strategies for sheduling beam time for TOTEM will be discussed in the light of the experience with polarization at LEP that had similar requirements. Some delicate points, like collimation with very small emittance, extreme requirements on beam position stability and accuracy will be analysed.

Speaker: Dr Jorg Wenninger (CERN)

slides Yet another update

Tuesday 18 January

Session 3 - Cryogenic and Vacuum Issues affecting Beam Commissioning

Conveners: Luigi (Scientific Secretary) Serio (AT-ACR), Noël (Chairman) Hilleret (AT-VAC)

15 How to deal with leaks in the QRL and magnet insulation vacuum

The influence of leaks on the cryogenic performance will be discussed and, as a consequence, different type of leaks will be defined: leaks that permit 200 days continuous machine operation, leaks that can be tolerated but require special measures, leaks that must be repaired. The various methods used to detect and locate leaks in the QRL and in the magnet insulation vacuum will be described and the repair scenario given with an estimation of machine downtime. The control tools required for an efficient diagnostic will be enumerated.

Speakers: Dr Germana Riddone (CERN AT-ACR), Mr Paul Cruikshank (CERN AT-VAC)

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16 HOW TO DEAL WITH LEAKS IN THE LHC BEAM VACUUM

The LHC beam vacuum system operates at cryogenic and at room temperature. Many aspects such as the location, the level of the leak flux, the reparability, the impact on the machine commissioning and operation shall be taken into account when dealing with vacuum leaks. The detection of warm air leaks is a difficult but mostly well mastered technology. Special attention will be paid to He leaks in a cryogenic environment which could arise during the period of beam commissioning and beam operation. The qualification of these leaks against beam operation, the diagnostics means and tools, the repair schemes and the expected downtime are discussed.

Speaker: Dr Vincent Baglin (CERN)

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17 Shortcuts during installation and commissioning: risks and benefits

The risks and benefits of shortcuts during the installation and commissioning of cryogenic equipments will be presented and analyzed. The talk will in general try to answer questions on what tests can be skipped and what are the consequences. The benefits and drawbacks of going directly for global system versus sub-system testing will also be investigated. Special attention will be paid to how we are dealing with non-conformities and the associated risks. An analysis of possible risks together with a quantitative assessment of the consequences on beam commissioning will be shown.

Speaker: Dr germana riddone (CERN)

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10:15 Coffee break

18 Commissioning the DFB

After a brief description of the functionalities of a DFB for the magnets powering, the strategy of transport, installation, commissioning and testing will be presented. The information that could be obtained from the test in SM18 of the first DFB will be explained together with the possible modification/consolidation to be performed during installation. The impact of DFB failures and availability on beam commissioning will also be presented together with the requirement and impact of in-situ repair and/or exchange and related downtime of the machine. Control requirements will be listed.

Speaker: Mr Antonio Perin (AT/ACR)

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19 The cryogenics system in pt 4: possible options

LHC cryogenics at P4 will be briefly recalled and present cooling power availability and possible limitations will be presented. The RF requirements in terms of capacity,pressure stability, operating modes and possible coupling with LHC machine operation and transients will also be analysed and discussed. Possible alternative cooling options for RF operation and sector 3-4 boosting will be analyzed together with the implications in terms of costs and resources. Controls requirements will be listed.

Speaker: Mr Serge CLAUDET (CERN AT ACR)

slides  Power point file

20 Issues concerning the reliability of the LHC cryogenic system

The functionalities, redundancy and possible failure scenarios of the cryogenic system will be briefly presented. The reliability of components and the impact on beam commissioning will be analyzed. Continuous versus cycled operation (thermal, pressure, etc.) will be investigated together with the requirements and problems related to the accessibility of components and radiation issues for in-situ components repair or exchange. A list of possible intervention for repairs will be given together with the associated downtime for beam commissioning. Finally the strategy for spares and maintenance (corrective against preventive) and the consequences on the system availability will be presented with the consequent intervention scenarios and machine access requirements.

Speaker: Mr Manel Sanmarti (AT-ACR, CERN)

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Session 4 - Other Issues affecting Beam Commissioning I

Conveners: Rhodri (Scientific Secretary) Jones (AB-BDI), Stephan (Chairman) Russenschuck (AT-MEL)

21 Electrical Quality Assurance (ELQA)

The electrical integrity and the safe operation of the superconducting electrical circuits are crucial issues for the successful commissioning with and without beam and for the operation of the LHC machine. Beam based measurements may require in- situ verification of the magnet polarities. The detection, diagnostics, repair and re-qualification of electrical faults and the verification of magnet polarities will inevitably have an impact on the machine availability. Therefore efficient and fast ELQA methods during beam commissioning shall be established and applied. This talk will initially outline the guidelines of the electrical quality assurance plan and will then depict some scenarios for electrical fault detection, magnet polarity error location and electrical re-qualification after magnet or lead exchange. Finally some aspects related to the acceptable status of affected electrical circuits will be given.

Speaker: Mr Davide Bozzini (CERN)

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22 Report from the Magnet Polarity Coordinator

The presentation will cover the polarity definitions and the conventions in the different coordinate systems used for beam tracking, field computation and magnetic measurements. In particular the definition of what a skew dipole magnet is, could lead to misunderstanding. Continuity problems in the spool piece bus bars which could affect corrector magnet polarity are addressed. The polarity of the main magnets with diodes has been verified relying only on Ampere’s law. The next steps will be the verification of the polarities in the insertion magnets (and in particular those which are installed in the tunnel with their connections pointing downstream of beam 1), the polarity of BI equipment, the handling of non- conformities etc.

Speaker: Dr Stephan Russenschuck (CERN AT-MEL-EM)

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23 Quench Protection System

Reiner Denz Quench Protection System (QPS) After a short introduction to the LHC Quench Protection System (QPS), an overview about the expected availability and reliability of the system will be given. The consequences of equipment failures and the required intervention times for repair will be discussed. The capabilities of the QPS data acquisition system with respect to cold mass diagnostics and fault identification will be presented. Finally a more detailed view on the dedicated protection systems for the LHC insertion region magnets will be given.

Speaker: Reiner Denz (CERN AT-MEL-PM)

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24 Consequences of RF system failures during LHC beam commissioning.

At nominal beam intensities, the loss of control of even a single RF cavity will require an immediate beam dump to avoid severe damage to RF equipment. During LHC beam commissioning, different beam structures and in particular lower intensities will be used. In this case it is possible that not all RF failures require a beam dump and that the beam may survive even if perturbed. Various RF failure situations and their consequences are analyzed and possible strategies are suggested to ease operation during the commissioning up to half the nominal beam intensity.

Speaker: Dr Trevor Linnecar (CERN)

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15:40 Coffee break

Coffee Break

25 Initial commissioning of critical beam instrumentation systems

This presentation will deal with the main beam instrumentation systems required for the initial commissioning period. The emphasis will be on the set-up and testing of the hardware involved, in particular BPM polarity checks, the determination of BLM interlock limits, tests of the electronics and calibration procedures. The amount of final testing for which the beam is required and the possible benefits of a sector test will be addressed as well.

Speaker: Dr Eva Barbara Holzer (CERN)

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26 The estimation of individual and collective intervention doses for the LHC beam cleaning insertions

The radiation protection of the personnel who will perform interventions in the beam cleaning insertions and install different phases of machine components is mandatory and includes the design of equipment and the establishment of work procedures. Dose rates are expected to reach values at which any maintenance has to be planned in advance and the design adopted in order to keep the accumulated dose as low as reasonably achievable (ALARA-principle). Three-dimensional maps of dose equivalent rates at different cooling times after operation of the LHC are available for IR7 and allow the calculation of individual and collective doses for different interventions. The latter would require information from the involved groups on intervention steps, duration and frequency. The presentation summarizes the results of detailed FLUKA- simulations and sketches its potential for optimizing, in an iterative way, the design of components as well as the layout of the beam cleaning insertions. Examples are discussed for the dose estimation based on detailed intervention scenarios and a first attempt is given to infer from it the annual collective dose. The derived value is compared to design constraints as well as the collective doses accumulated during SPS interventions. It is also put into perspective with annual doses reported by other laboratories and the nuclear industry.

Speaker: Markus Brugger (CERN SC/RP)

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27 The LHC Access System: why do we put doors ?

The latest discussions on the LHC Access Safety system, held during the first sessions of the Access Safety Working Group, have emphasized the goal of the system to prevent personal exposure to radiological hazards. The personnel protection against electrical hazards is outside the scope of the project. From the control room point of view, the LHC Access Safety System will authorize, when all the safety conditions are met, either the beam operation, or, the access operation using the LHC Access Control system. A test mode is foreseen for the RF zone to protect the personnel against the X rays generated by the cavities during the cavities testing. The LHC Access Control System has however several operational modes and functionalities, which can be used with the appropriate procedures to perform other equipment tests. The LHC Access Control system will be installed following to the LHC installation planning and could be operated point by point, however as the LHC Access Safety system concerns the whole accelerator no partial operation is possible, at the exception of the interlocks required by the RF zone.

Speaker: Dr Luigi Scibile (TS/CSE)

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Wednesday 19 January

Session 5 - Other Issues affecting Beam Commissioning II

Conveners: Oliver (Chairman) Bruning (AB-ABP), Verena (Scientific Secretary) Kain (AB-CO)

28 Milestones for the lead injector complex commissioning

The LHC physics programme with heavy ions (lead-lead) collisions at a luminosity of 1027 cm-2s-1 can be achieved by upgrading the ion injector chain: Linac3-LEIR-PS-SPS. The conversion of the Low Energy Antiproton Ring (LEAR) to a Low Energy Ion Ring (LEIR) has already started. The conversion includes new magnets and power converters, a high-current electron cooling system, broad-band rf cavities, upgraded beam diagnostics and vacuum equipment to achieve 10-12 mbar. The start-up of the beam commissioning is planned for summer 2005. The impact on the proton LHC start-up of the major hardware changes in Linac3 (installation of the new ECR source and the test of the energy ramping cavity), LEIR, PS (new injection system, rf gymnastics),the stripping insertion between PS and SPS and their commissioning is discussed The milestones, schedule and an estimation of the lead beam brilliance and intensity in LHC are tentatively shown.

Speaker: Mr Stephan MAURY (CERN)

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29 Experience with the TI 8 and TT40 tests

The LHC transfer line TI 8 was commissioned with beam in the autumn of 2004. This talk outlines the tests performed and their conclusions regarding measured beamparameters, optics, beam instrumentation, control system and machine protection system. In the same period the LSS4 extraction c hannel and TT40 line were commissioned with high intensity beams. The important lessons on machine protection and operational procedures learned from a beam loss incident are summarised. An extrapolation of the experience obtained during both tests towards LHC commissioning is made.

Speaker: Dr Jan Uythoven (CERN)

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30 Overview of the LHC and transfer line optics configurations and tolerances

The SPS and LHC optics have already changed during the design phase and can be expected to further change during operation. The combined system of SPS, TI 2, TI 8 and the LHC should be well matched to allow for clean injection and minimum emittance blow-up. This implies that the transfer lines have to provide some flexibility. In addition to the requirement to match to the SPS and LHC, there are also internal constraints in the transfer lines on the phase advance differences between collimators. The expected range of optics changes and the requirements to match these will be critically analysed.

Speaker: Dr Helmut Burkhardt (CERN)

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31 Experience with the transfer line matching and options for improving the transfer line flexibility

The matching sections at the SPS and LHC ends of TI8 were designed several years ago. The magnet positions and powering were optimised to match the constraints existing at that time. For various reasons the boundary conditions at both the start and the end of the line have changed. Unfortunately, changes in dispersion cannot easily be absorbed, as the number of individually powered quadrupoles at large dispersion is small. By powering the existing quadrupoles in a different way the matching sections can be made more flexible. Increasing the number of power converters may not be necessary. The installation of skew quads to absorb the tilt mismatch at the end of the line is no longer envisaged.

Speaker: Thys RISSELADA (CERN)

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10:25 Coffee Break

32 Safe Injection into the LHC

The LHC injection process comprises extraction from the SPS, transfer through the transfer lines TI2 and TI8 and finally injection into the LHC in IR2 and IR8. The nominal intensities foreseen for injection are well over an order of magnitude above the damage limit. Equipment failures resulting in beam loss will therefore cause severe damage to the SPS, the transfer lines or the LHC. Effective active (interlock) and passive (collimator) machine protection is therefore essential. The consequences of various failures such as kicker erratics, power converter faults, etc. have been investigated for beam 2 with particle tracking using a full aperture model of the transfer line and the injection region. Mechanical and optical imperfections of the line and injection region were taken into account. The requirements for active protection by surveillance of key equipment and passive protection (TCDI, TDI-TCLI) are presented. Consequences for the commissioning phase of the LHC are discussed in the context of the likely LHC commissioning strategy.

Speaker: Verena Kain (CERN)

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33 Experiments’ equipment directly interfering with the beam operation

All four experimental insertion regions will be equipped with movable devices which, in some cases, have to be located very close to the beam. In addition both ALICE and LHCb use spectrometer magnets which distort the beam trajectories. Their effect therefore, has to be compensated locally with dedicated compensation magnets. The location of this experimental equipment and the signals used for its positioning will be presented. The various operation scenarios will be discussed together with the experiments’ proposals for who will be responsible for these operations.

Speaker: Dr Daniela Macina (CERN)

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34 Experiment-machine interface issues and signal exchange

This report provides an overview of issues arising at the interface between the LHC machine and the experiments. These issues will be required to guide the interaction between the collider and the experiments when operation of the LHC commences. In particular, the analysis of signals and parameters to be exchanged between the experiments and the accelerator will be presented. Emphasis will be placed on observables that can proviode a measure of the LHC machine operating conditions for the experiments and that can be used by the experiments to give feedback to the machine operation as well as to protect their detectors against damage from spurious operating conditions of the machine.

Speaker: Dr Emmanuel Tsesmelis (CERN)

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Session 6 - Effects of the compressed Schedule on the Installation

Conveners: Felix (Scientific Secretary) Rodriguez Mateos (TS-HDO), Thomas (Chairman) Pettersson (TS-CSE)

35 Update on LHC installation schedule

The impact of the QRL delay on the schedule will be discussed. A number of activities will have to be executed in parallel. A compressed schedule needs to be compatible with the resources available in the various groups involved. The manufacturing limitations and the possibilities to provide the required equipment at the required dates may also lead to dangerous shortcuts. The talk will describe how the input from the different equipment groups is taken into account by the master schedule planning team with respect to equipment availability and production as well as logistics and safety issues in the tunnel.

Speaker: Dr Sylvain Weisz (CERN)

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36 Compressed Schedule - The layout point of view

The precise knowledge of what needs to be installed is clearly a prerequisite to the fast schedule feasibility. The talk will give an overview on the expected configuration of the as-should-be-built LHC (v6.5), the LHC reference database and the tools available to access it. The areas where information is still missing or where the integration is not finalized will be listed and actions required discussed.

Speaker: Mr Samy Chemli (CERN)

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37 INSTALLATION OF LSS

The installation of the various LSS is a challenge in the compressed schedule. The installation scenarios describing the sequences presently planned will be discussed and potential problematic areas will be highlighted. The particular case of sector 7- 8 where the LSS elements will be installed before the QRL line is completely terminated will be used as an example of a ‘rapid’ installation scheme to illustrate how resources are used. The consequences of possible shortcuts will be also mentioned.

Speaker: MARIA SONIA BARTOLOME JIMENEZ (CERN)

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15:20 Coffee Break

38 Magnets Cold Tests and Throughput

The Testing Facility in SM18 has a test programme destined to verify the electrical, cryogenic and quench performance of the magnets for machine operating conditions as well as providing a sampled field quality evaluation. From the magnet production and delivery points of views the test programme is used to monitor the overall magnet manufacturing quality. Given the environment and present limits of the Testing Facility, these different objectives impose somewhat conflicting requirements on the SM18 operation. LHC beam quality requirements may also necessitate more sampling and longer, additional magnetic measurements. In addition, the fixed machine installation completion date, the compressed schedule and a parallelised installation process will potentially require a higher supply rate of tested magnets or of specific types than presently achieved. The talk will discuss the SM18 environment and its limits and give an overview of magnet testing throughput based on current experience and results.

Speaker: Dr Vinod Chohan (CERN)

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39 Hardware Commissioning

Following the uncertainty of the installation schedule, the HCWG focussed on the commissioning of two sectors around an even point in parallel augmented by a number of additional constraints. This exercise, which was published as a Management Report, yielded commissioning times and resource needs which can be scaled –within reasonable limits- to the requirements of the final installation schedule. Both the durations of the different phases and the personnel required have been estimated in the light of previous experience at the String and during Hera commissioning. The current trend of reducing the time available for hardware commissioning cannot continue indefinitely. The hard limit is reached when the time taken by the test procedures and by the result interpretation cannot be further shortened but also when additional resources to obtain shorter times cannot be added. The talk will describe how the evaluation exercise was conducted, focus on the test procedures, quality assurance and decision making process, propose alternative strategies for deploying additional manpower and finally emphasize the need for first-rate service from the infrastructures and software applications.

Speaker: Roberto Saban (CERN)

paper paper

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40 Controls

The roadmap towards fully operational LHC controls will be discussed. Controls for beam operation are similar to other CERN accelerators. From the experience gained in the TI8 tests, with milestones such as the commissioning of LEIR, TI2, the controls for LHC will be realised with the same building blocks as used today. Hardware commissioning will provide a different challenge with an large scale use of industrial solutions for accelerator control. Already long before first injection into the LHC, controls for vacuum, cryogenics, quench protection, powering interlocks and power converters must be fully operational. Current plans for the installation and commissioning of the controls infrastructure will be explained and the main aspects highlighted. The generic controls facilities required for the commissioning of the hardware and for beam operation will be discussed with emphasis on how the work advances in the different domains (post-mortem, logging, alarms, timing, specific applications, etc.). The requirements, in particular for Hardware Commissioning, and how they translate into existing controls and / or technical specifications will be addressed. The presentation is based on the summary of a AB-CO meeting (CO-Day) that is being organised in December.

Speaker: Mr Rüdiger Schmidt (CERN)

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Thursday 20 January

Session 7 - Magnet Issues affecting Beam Commissioning

41 What are today’s issues in the production of the Main Bends and Quads ?

The LHC main magnet production is well beyond half way and today the end by September 2006 is in view. Warm and cold test assures us that the LHC nominal targets are well at hand, while final assessment for the ultimate performance needs a further year of cold testing. The dipoles quench level, which is recovering toward the extremely good performance of the beginning of the pre-series, after a certain weakening in the productions of the 2nd and 3rd octants, will be discussed in view of the commissioning parameters. The action taken at the manufacturers in order to improve as much as possible production quality and robustness (see for example recent electrical problems in the SSS) in this last period of production will be reported. Repair vs. replacement strategies will be reviewed, on the base of the decision on spares taken in 2004 and in view of realistic assumptions on human and financial resources available in the concerned departments, in order to derive what and when possible actions must be triggered to optimize interventions, during commissioning and operation.

Speaker: Prof. Lucio Rossi (CERN)

Slides Slides

42 What are today's issues for all other magnets.

The status of the corrector magnets and of the warm and cold magnets in the insertion region is discussed, as well as issues with the injection line magnets. In particular the performance in view of the commissioning is adressed. Other points discussed are spare and repair policies.

Speaker: Dr Karl Hubert Mess (CERN AT-MEL)

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43 What will the geometry of the Main Bends and Short Straight Sections (SSS) be ?

We make a brief overview of activities related to the geometry of the main dipole and the main quadrupole. The blocking of the central support of the dipole has contributed to the stability of the cold mass in the cryostat. Work on the measurements of the spool pieces (magnetic and mechanic) has been carried out. Collection of measurements on the quad axis measurements in data bases has been made and a first report on these measurements can now be made. Work on the vertical alignment has given results for the position of the ends of the dipole. We will give a review of the results of the measurements and the analysis made so far: the shape (the axis), the interconnectivity and the spool piece positioning. We will also give some results for the cold warm relations. The effect on geometry of interconnection and the aperture and the feed-down related to shifts will be discussed. First results on the long term stability and related issues will be mentioned.

Speaker: Elena Wildner (CERN)

paper paper

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10:15 Coffee Break

44 Estimates of the LHC magnetic optics versus requirements

The expected field quality of the main magnets of the LHC based on the measurements carried out over a significant fraction of the production is given. Main dipoles, main quadrupoles and insertion quadrupoles are analysed.The more critical parameters and cases of field components out of targets are pointed out, and the implications on the beam optics are outlined.Corrective actions that could still be taken to improve the field quality at this advanced stage of production are discussed.

Speaker: Dr Ezio Todesco (CERN)

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45 How the magnetic measurements and the Reference Magnet System (RMS) will be used for commissioning ?

The talk gives a summary of data (and their location) as is planned to be collected in warm and cold conditions in the various LHC magnets. This data can and shall be made available for start-up. I will present a view on how the data can be used, in practice, to prepare for injection, forecast ramps of the main magnets and correctors. To achieve this we need information from standard tests, that provide information on magnets field quality to be compared directly to production specifications and for characterization of the static behaviours, as well as extended tests that are presently performed on a one-by-one basis to ascertain scalings in the injection behaviour, and to verify long term changes. One of the matters presently investigated is snap-back scaling that could provide accurate forecast at the beginning of the ramp. I will detail on this. Finally, as most of these ideas were discussed at the July RMS review, I will give a status of the related activities.

Speaker: Mr luca bottura (MTM)

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46 Magnetic behavior of the correctors: issues for machine operation

The contribution will concentrate on the aspects of the magnetic behaviour of correctors which may be relevant for the machine operation. Warm measurements,measured excitation curves at cold, correlation between the warm and cold field measurements and comparisons of the field quality to the targets for LHC will be discussed. The measured magnetic hysteresis and its possible influence on setting errors during operation will also be presented, as well as estimations of the order of magnitude of cross talks, both for the spool pieces and for the lattice corrector circuits. Finally the strategy for the field measurements of correctors will be reviewed.

Speaker: Walter Venturini Delsolaro (CERN)

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47 Are there issues due to a long term outdoor storage ?

Due to delayed start of magnet installation, about 800 dipoles are being stored outdoor waiting for being transported to the LHC tunnel. To explore in details the possible impact of such a storage on the cryodipole system (magnetic, electric,training, mechanic, geometry, cryogenic, vacuum) a dipole long term stability (DLTS) task force has been organized. After an overview of the main steps a dipole has to undergo from arrival at CERN to installation, the talk will report on the avancement of the DLTS.

Speaker: Mr Davide Tommasini (CERN)

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48 Installation strategy: which lessons from sector 7/8?

This talk is the summary of the Magnet Evaluation Board experience in the magnet allocation for the sector 7-8. I will outline the role and functioning of the Board, and its evolution since beginning of 2004. I will then describe the installation algorithm followed, with some reasoning on the background and the expected gain in terms of mechanical aperture, of dynamic aperture, and overall performance. I will give practical examples where the work had to be adapted to schedule or other constraints, and the compromise found in these cases. The lesson learned, and the changing work hypothesis on storage and installation, are such that the slot allocation procedure is changing to an optimization over a complete arc. I will finally discuss open points such as the difficulty found in completing a sector, the allocation of magnets other than dipoles, and possible flexibility in moving allocated magnets to other sectors.

Speaker: Mr luca bottura (MTM)

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Session 8 - Machine Protection Issues affecting Beam Commissioning

49 Machine Protection System(s) - Overview

Safe operation of the LHC requires coherence across several systems for machine protection: collimators and beam absorbers, beam dumping system, beam monitoring, beam interlocks, etc. Beam operation requires beam permit that can only be established when all LHC systems are ready for beam operation. Extraction of beam from the SPS and transfer to the LHC requires correct settings of the extraction and injection systems as well as the transfer line elements. When operating with beam, many different type of failures could lead to accidental beam losses. Failures are detected by the quench protection system and other hardware related equipment. Consequences of failures on the beam are detected by beam loss monitors and other beam instruments. This results in a beam dump request transmitted via the beam interlocks to the beam dumping system, that extracts the beam into the dump block. The functionality of the LHC systems with respect to machine protection is presented. The overall strategy of the LHC machine protection is discussed. Main emphasis is on the interfaces and dependencies between the systems.

Speaker: Mr Ruediger Schmidt (CERN)

poster  

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50 Collimators and Beam Absorbers for Cleaning and Machine Protection

An inventory of all collimators and beam absorbers in the LHC ring is presented. The required settings of the various devices are discussed, the roles in beam cleaning and machine protection are explained and limitations are explored. A basic strategy for commissioning of all collimators and absorbers is explained, including a specification on the necessary prerequisites on optics, orbit, etc. The required cleaning performance and protection is discussed as a function of beam intensity and various required steps in commissioning of collimators and absorbers are presented.

Speaker: Dr Ralph Assmann (CERN)

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15:55 Coffee Break

51 LHC aperture and commissioning of the collimation system

The LHC aperture for the perfect machine and its dependence on various optics imperfections are discussed. The optics tolerances required to meet the desired performance of the LHC collimation system are given. These studies are based on the results of tracking simulations of the beam halo and on a detailed aperture model of the full LHC ring, with spatial resolution of 10 cm over the total length of 27 km. Experimental results from the collimator tests with beam at the SPS are reviewed and specific issues related to the commissioning of the LHC collimation system are discussed.

Speaker: Dr Stefano Redaelli (CERN)

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52 Beam instrumentation other than BLMs linked to the machine protection system

The beam loss monitoring system will be the main instrument charged with detecting and acting upon the majority of failures that could lead to quenches or damage. In a few cases, however, additional instrumentation is required to protect the machine. Three such systems will be discussed along with their proposed implementation,namely: the beam dump channel position interlock in IR6, a fast orbit drift interlock and a fast loss interlock using beam current transformers. For many types of failures these systems would also be a back-up to beam loss monitoring thus inceasing the overall reliability of the machine protection system.

Speaker: Dr Rhodri Jones (CERN)

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Friday 21 January

Session 8 - Machine Protection Issues affecting Beam Commissioning

53 Commissioning of the protection systems

At the LHC the machine protection and interlock systems will be major players that need to keep track with the evolution of the machine in terms of beam energy and intensity. At the start of beam commissioning, many protection systems will already be partially commissioned. This presentation will outline the state of the various protection systems at the start of beam commissioning and discuss how to bring up one system after another as the beam intensity and energy is increased.

Speaker: Dr Jorg Wenninger (CERN)

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54 Objects Capable of Touching the Beams

The beams in the LHC can be intercepted by many different types of objects moving into the vacuum chambers. These include devices designed for beam monitoring,machine protection and for data taking by the experiments. Moving these objects can only be permitted under certain conditions. Interlocks should prevent quenches or even damage in case of wrong actions. A complete inventory of such devices will be given along with the conditions under which they can be moved and the interlocks,or signals, that are required to ensure they cannot be activated at other times. A particular issue concerns the optics imperfections which can change significantly the safe position settings for a given mobile device. Controlling the orbit and beta-beating errors is therefore an important pre- requisite to commissioning protection devices and the collimation system.

Speaker: Dr Paul Collier (CERN)

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55 Will we ever get the green light for beam operation

The primary task of the machine protection system is to prevent equipment damage. To guarantee the required system reliability the subsystems have evolved in large andoften complex systems. As a result the machine protection system could become a major cause of machine downtime by triggering too many false beam dumps. The talk will present the major components of the machine protection system and the method used to calculate the dependability of the system. The results of a study of a subsystem are given, resulting in the estimated number of requested beam dumps which will not be correctly executed (safety) and the number of false beam dumps per year initiated by the subsystem (availability).

Speaker: Dr Jan Uythoven (CERN)

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10:15 Coffee Break

56 Beam loss induced quench levels

An accurate prediction of the quench levels of the main ring superconducting magnets will allow a preventive dump of the beam before the magnet quench based on beam loss measurements with beam loss monitors, thus limiting the downtime of the machine. The particle energy deposition in the coils is calculated by using simulation programs like GEANT or FLUKA. The magnet quench level as a function of proton loss distribution and magnet specific parameters can be estimated using codes like SPQR and ROXIE. Until now simplified analytical calculations have been done for the main dipole magnets. In this presentation the current knowledge of the quench levels of various families of the main ring superconducting magnets will be addressed, taking into account experience from other colliders and from magnet tests at CERN. An outlook on further simulations for the quench levels and envisaged experiments to validate the simulations will be discussed.

Speaker: Dr Andrzej SIEMKO (CERN AT-MTM)

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57 Damage Levels: Comparison of experiment and simulation

The design of protection elements is based on assumptions on damage levels, which are in general derived from computer simulations. A dedicatedexperiment was carried out to cross-check the extracted from the SPS in TT40, deliberate damage of material was done in a controlled way. A simple geometry was chosen for the high-Z target comprising several typical materials that are used in the LHC, such as stainless steel and copper. Results of the simulations are presented and compared with experiments. Simulation results for the damage of a beam pipe in TT40 during an accident with the high intensity extraction are compared with observations. An outlook of what is required to predict beam induced damage levels in the LHC with confidence is given.

Speaker: Verena Kain (CERN)

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Session 9 - Impacts on Efficiency of Beam Commissioning - Collection: Discussion

Conveners: John (Scientific Secretary) Poole (AB), Steve (Chairman) Myers (AB)

14:30 Discussion 1

16:00 Coffee break

16:30 Discussion 2

Wednesday 2 February

Summing-up

Summing-up of the Chamonix XIV sessions

58 Introduction

Speaker: Steve Myers

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59 Summing-up of Session 1 LHC Commissioning with Beam

Speaker: Mike Lamont (AB-OP)

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60 Summing-up of Session 2 - Scheduling LHC Operation

Speaker: Roger Bailey (AB-OP)

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61 Summing-up of Session 3 - Cryogenic and Vacuum Issues affecting Beam Commissioning

Speaker: Noel Hilleret (AT-VAC)

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62 Summing-up of Session 4 - Other Issues affecting Beam Commissioning I

Speaker: Stephan Russenschuck (AT/MEL)

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15:15 Coffee break

Coffee break

63 Summing-up of Session 5 - Other Issues affecting Beam Commissioning II

Speaker: Oliver Bruning (AB-ABP)

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64 Summing-up of Session 6 - Effects of the Compressed Schedule

Speaker: Thomas Pettersson (TS/CSE)

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65 Summing-up of Session 7 - Magnet Issues Affecting Beam Commissioning

Speaker: Jean-Pierre Koutchouk (AT/MAS)

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66 Summing-up of Session 8 - Machine Protection Summary

Speaker: Rudiger Schmidt (AB/CO)

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67 Issues Effecting the Efficiency of Beam Commissioning

Speaker: Steve Myers (AB)

Slides Slides

16:45 Discussions

Discussions