# Chamonix 2011 LHC Performance Workshop

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Chamonix
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• Monday, 24 January 2011
• 08:30 - 12:30 Session 01 Review of 2010 Operations
 Conveners: Malika Meddahi (Chair), Laurette Ponce (Scientific Secretary) paper
• 08:30 LHC Operation – as viewed from the Experiments 20'
This talk will try to summarize how the LHC experiments have perceived the 2010 run. A critical review of LHC operation, beam conditions and luminosity delivery will be given, as well as proposals for improvements.
 Speaker: Massimiliano Ferro-Luzzi (CERN) Paper Slides
• 09:00 Operational challenges (Feed forward from Evian LHC operation workshop) 20'
An attempt is made to synthesize the outcomes of the Evian workshop. A list of issues and prioritized actions will be presented. Among others the following issues will discussed: overall operational efficiency and potential improvements; possible optimization of the operational cycle; machine configuration and associated commissioning requirements; adequacy of LHC operational procedures and tools.
 Speaker: Mike Lamont (CERN) Paper Slides
• 09:30 Injection – issues and potential solutions 15'
Due to the sensitivity of the LHC beam loss monitor systems combined with low thresholds, losses at injection became a limiting factor during the filling of the LHC. All parameters, longitudinal and transverse had to be well controlled not to trigger the beam dump at injection. The cause of these losses will be summarized and typical loss patterns and other diagnostics described. Mitigation measures together with promising first results will be presented together with the plans for 2011. Finally the weak points of the current injection procedure will be discussed in terms of efficiency and protection, improvements for the 2011 run will be proposed.
 Speaker: Miss. Verena Kain (CERN) Paper Slides
• 09:50 Coffee break 30'
• 10:20 Vacuum and Cryogenics observations for different bunch spacing 15'
Following the observations of high pressure rises induced by an electron cloud building up in the LHC beam pipes, studies were launched with beams with 50 and 75 ns bunch spacing at injection energy and with a ramp to 3.5 TeV (only 50 ns bunch spacing).
This talk will summarize the observations made on the beam vacuum and cryogenic systems for both 50 and 75 ns bunch spacing and with a ramp in energy (only 50 ns bunch spacing). Some extrapolations will be presented based on the measurements. Finally, the decided mitigation solutions and beam parameters to be used for the 2011 run will be reviewed.
 Speaker: Dr. Jose Miguel Jimenez (CERN) Paper Slides
• 10:45 Beam observations with different bunch spacing and overall synthesis 15'
Machine studies have been performed at the end of the 2010 proton run to study the machine performance with bunch trains with 50 and 75 ns spacing in preparation for the proton run in 2011.
The results of the observations and measurements will be summarized and compared with existing models. Possible running scenarios for 2011 will be outlined.


 Speaker: Gianluigi Arduini (CERN) Paper Slides
• 11:10 How can we reduce the "no beam" time? 20'
The machine operational efficiency will be analyzed by looking at the downtime statistics over the 2010 run. Hardware reliability will be reviewed and possible improvements considered. Access management, access recovery, duration and frequency of scheduled technical stops will also be discussed. Finally, the overhead of switching to ions and back will be briefly addressed.
 Speaker: Dr. Walter Venturini Delsolaro Paper Slides
• 11:40 Optimisation of the nominal cycle 15'
The energy ramp and the betatron squeeze are critical phases of the LHC operation. During the squeeze, delicate optics manipulations take place when the stored energy is maximum. Ramp and squeeze were commissioned rapidly and smoothly became operational. On the other hand, for the first commissioning exercise, the focus was put on machine safety and on operational robustness rather then in efficiency for luminosity production. After having cumulated a full year of experience and having gained important feedback on the machine behaviour and on the operational procedures, it is now time to address efficiency optimization while still respecting safe boundaries. In this paper, the experience with ramp and squeeze is reviewed, possible bottlenecks are identified and paths for improvements of the nominal LHC cycle are addressed. More complex operation configurations, like combined ramp and squeeze or dynamics squeeze with colliding beams, are also addressed.
 Speaker: Dr. Stefano Redaelli (CERN) Paper Slides
• 12:00 Discussion 30'
• 16:30 - 17:00 Coffee Break
• 17:00 - 20:20 Session 02 Shutdown 2012 (Part 1)
 Conveners: Simon Baird (Chair), Katy Foraz (Scientific Secretary)
• 17:00 Which systems (except main circuits) should be commissioned/tested for 7TeV operation before the long shutdown? 15'
The key driver of the long 2012/13 shutdown is the Consolidation of the 13 kA splices. Once the machine will be back to operation, the increase of energy to 7 TeV should be possible. Are all circuits and systems ready for 7 TeV operation? This talk will focus on what else could limit LHC high energy operation and how we can know that in advance. A period of dedicated testing at the end of operation and before the long shutdown could give a precious knowledge on the status of the machine.
 Speaker: Dr. Mirko Pojer (CERN) Paper Slides
• 17:25 What are the consequences of delaying the shutdown from 2012 to 2013 for Radiation Protection? 10'
The residual induced radio-activity in the LHC underground areas in 2012  will be estimated (assuming 200 days of high intensity proton operation in 2011). These estimates will be compared with the levels that would be expected in 2013 (assuming 200 days of high intensity proton operation in both 2011 and 2012). With these estimations some consequences of delaying the shutdown from 2012 to 2013 will be presented.
 Speaker: Stefan Roesler (CERN) Paper Slides
• 17:40 Splice Consolidation. What will we do? 15'
In the frame of the next long shut-down of the LHC, it is foreseen to intervene on all the 13kA interconnections in order to guarantee the necessary margin and redundancy to provide safe LHC operation at 7 TeV. In this talk we will provide an overview of the development work performed in 2010, the current technical solution and validation test results, and the remaining work to be performed in preparation for the long shutdown.
 Speaker: Paolo Fessia (CERN) Paper Slides
• 18:05 Work organization for splice consolidation 15'
The Splices Task Force has worked in 2010 to prepare the necessary interventions for 7 TeV operation. The design solution for consolidating the main interconnection splices is well advanced. The required activities to implement it are described, highlighting working assumptions, missing resources and schedule considerations.
Progress has also been made in assessing other splices, 6 kA praying hands and corrector circuits: results and ongoing work are presented, highlighting priorities for the remaining work.

 Speaker: Francesco Bertinelli (CERN) Paper Slides
• 18:30 break 10'
During the next long shutdown, the majority of the 557 LHC beam and insulation vacuum volumes must be vented and opened. The activities proposed by the Vacuum, Surfaces and Coatings Group will be elaborated, including their implications for other Groups, together will an estimation of the extensive VSC workload that is generated by other activities eg splice consolidation, new collimators and experimental area upgrades.
 Speaker: Dr. Vincent Baglin (CERN) Paper Slides
• 19:05 Installing collimators in the next long shut-down: plans, status and challenges 15'
The first part of the collimation upgrade plan features the installation of 4 collimators in the 2 DS of point 3, in addition to the upgrade of the existing collimation system.
What makes this upgrade so special is that for the first time collimators will be placed within the continuous cryostat of the LHC sectors. For this purpose, 16 main dipoles and 8 main quadrupoles will have to be disconnected and displaced by about 4.5 m, as well as the 2 electrical feedboxes (DFBAs) on either side of the DS, in order to create the space required for installing the additional collimators. The collimators themselves, although remaining of the warm type, feature a design substantially different from the others, mainly imposed by tight space constraints. These collimator modules will have to be complemented by a special bypass cryostat whose function is to preserve the continuity of the technical systems along the arcs (magnet powering, cryogenics and insulation vacuum), while providing cold to warm transitions to the beam tubes where the collimators are placed.
The status of this collimation upgrade project will be presented, with special emphasis to the collimation in the DS of point 3; design & integration studies in this point, as well as the status of the design and manufacturing of all the associated new equipment (DS collimators, Short Connection Cryostats, and new cryogenic extensions to the QRL) will be outlined. An overall plan of the surface and tunnel preparation activities, in the perspective of a 2012 shut-down implementation, is discussed.
 Speaker: Vittorio Parma (CERN) Paper Slides
• 19:30 Cryogenic systems : which consolidations shall be done in 2012/13 ? 15'
The operation of the cryogenic systems during the first two years at half of the nominal energy has highlighted a number of required consolidations. The main projects will be reviewed with emphasis on safety issues, LHC downtime risk and cryogenic systems performance. Finally their status, cost, resources and planning will be summarized.
 Speaker: Olivier Pirotte (CERN) Paper Slides
• 19:55 Cryomagnets, Interconnections, Superconducting Circuits: What to do in 2012/13 if you are not consolidating splices ? 15'
The interventions affecting the cryomagnets, the interconnections and/or the superconducting circuits, excluding main splices consolidation and QPS interventions will be presented. All the tasks not covered in other talks of this session will be detailed, especially:
the replacement of cryomagnets,
the consolidation of the connection cryostats,
the repair of interrupted Y-lines,
the installation of safety pressure relief devices (DN200 & 160),
the consolidation of some SAM helium level gauges,
the investigations of open issues like high resistance splices and superconducting circuits non-conformities

Finally, the present plan, work organization and workload for these activities including DS collimators installation, interventions on the beam lines and leaks localization and repair, will be summarized.
 Speaker: Jean-Philippe Tock (CERN) Paper Slides
• Tuesday, 25 January 2011
• 08:30 - 12:40 Session 03 Shutdown 2012 (Part II)
 Conveners: Simon Baird (Chair), Katy Foraz (Scientific Secretary)
• 08:30 QPS Activities 15'
The long shutdown activities of the Circuit Protection section form integrated parts of the medium- and long term plan for the consolidation and upgrade of LHC detector and extraction equipment which is required for maintaining and adapting the complex and safety-critical QPS systems. Although every coming TS shall be efficiently used to advance with these works, a major part of the tasks, defined in five project packages, will need to be implemented during the shutdown. The packages are: nQPS/BS extension to the SAM’s, the HDS upgrade, a EE consolidation plan , general and specific firmware upgrades and a R2E mitigation and replacement program, representing an estimated total of 55-60 man-months.
 Speaker: Knud Dahlerup-Petersen (CERN) Paper Slides
• 08:55 Kickers and dumps 15'
Planned major hardware interventions include the completion of the staged dilution kicker system in point 6 (installation of 2 last tanks and associated generators), replacement of the extraction protection elements TCDQ (for performance reasons) and possibly the replacement of 2 injection kickers. The reliability overhaul program for the extraction kicker generators will be completed, and numerous improvements of electronics and controls of the various systems be carried out, followed by a thorough test and re-qualification program.
 Speaker: Volker Mertens (CERN) Paper Slides
• 09:20 The LHC RF System: plans for the next long shutdown 15'
The potential limitations for future running of the LHC RF systems are presented. In particular the problems of trips, hardware failures and limitations encountered during 2010 operation period are discussed, with emphasize on the possible hardware modifications and upgrades during the next long shutdown. The main technical challenges as well as the consequences of delaying the shutdown from 2012 to 2013 are highlighted.
 Speaker: Olivier Brunner (CERN) Slides
• 09:45 R2E relocation and shielding activities 15'
In the framework of the R2E mitigation project, relocation and shielding campaigns will be performed during the next long shutdown in parallel in Points 1, 5, 7 and 8. About 15 groups will be involved in these R2E activities with work periods from few days to several months. The baseline for these relocations and shielding installations is today defined. The status of the integration studies and their constraints will be discussed aiming for the different teams to be ready for the 2012 shutdown. The impact on the work achievement of a possible delay of the R2E activities by one year will be presented.
 Speaker: Anne-Laure Perrot Paper Slides
• 10:10 Coffee Break 20'
• 10:30 CV 15'
The presentation gives an overview of the major projects and work foreseen to be performed during the long shutdown on cooling and ventilation plants. Several projects are needed according to the experience of the last years, in particular the modifications in the water cooling circuits presently in overflow. Some other projects are linked to the CV consolidation plan. Finally, most of the work shall be done to respond to several requests: SR buildings air conditioning, the need to be able to clean and maintain the LHC cooling towers without a complete stop of cooling circuits, the upgrade of the air conditioning of the CCC rack room cooling etc. For all these activities , the author will detail  constraints and the impact on the schedule and on the operation of the plants that will however need to run for the major part of the shutdown. The consequence of having the long shutdown in 2013 will be also covered.
 Speaker: Serge Deleval (CERN) Paper Slides
• 10:55 EL Activities during 2012 Long Shutdown 15'
EN/EL will be leading 3 main LHC projects:
-	R2E (relocation of EL equipment in LHC points 1, 5, 7 and 8)
-	Water cooled cables to be replaced in 3 LHC points
-	UPS (APC SILCON) to be replaced (circa 80 units)
EN/EL will be involved in many others. Only a few of them are known today. (Vacuum pump cabling, RF cables replacement, QPS cabling …..)
Several non LHC projects but directly connected to LHC runs will required a major contribution from EN/EL. Computer center, B513 upgrade and CCC upgrade will be the main ones.
Several EL Consolidation works on the power distribution network are more or less affecting LHC operations:
-	Prevessin distribution substation & 3.3kV safety network
-	Upgrade/consolidation of 66kV substation protection system
-	Upgrade of SW (ME59) substation (including 66/18kV trafo)
-	400kV maintenance on both CERN & RTE sides
And many other tasks, not connected to LHC operations, will sharply increase the EL turnover for the shutdown..
Postponing the long shutdown from 2012 to 2013 will mainly:
-	 increase the risk on SPS irradiated cables (no replacement since 2008/2009 campaign)
-	Induce schedule changes on CC, B513 upgrade project
-	Postpone for the 3rd time RTE maintenance on Bois-Tollot substation and Genissiat power line
 Speaker: Francois Duval Paper Slides
• 11:20 Access and Alarm Safety Systems - Activities for the 2012/2013 Long Shutdown 15'
This paper presents the 2012/2013 long shutdown activities for the access, emergency evacuation, gas and fire detection systems. First, an overview of the required minimal annual maintenance and tests is presented, including the first feedback from the 9 weeks of the technical stop. Second, planned upgrades, new installations and consolidation activities, such as the R2E relocations and systems improvements, are discussed. For all these activities, the required resources are estimated, the constraints on other groups are listed, the associated risks analyzed and time estimation provided. The evaluation of the required resources takes into consideration the activities in the injector chain during the long shutdown.
 Speaker: Silvia Grau (CERN) Paper Slides
• 11:45 What do the experiments have planned? 15'
The shutdown in 2012-13 is the first opportunity since physics operation started for the experiments to conduct comprehensive maintenance. This long shutdown will also be used to consolidate and upgrade the experimental apparatus so as to fully exploit the expected improvements in LHC performance. This talk will summarise the planned activities in all experiments and attempt to identify areas where resource conflicts may arise.
 Speaker: Austin Ball (CERN) Paper Slides
• 16:30 - 17:00 Coffee Break
• 17:00 - 19:50 Session 04 Beam Energy
 Conveners: Dr. Andrzej Siemko (Chair), Marco Zanetti (Scientific Secretary)
• 17:00 How much Physics benefits from running at higher energies? 20'
In 2010 the LHC experiments accomplished stunning physics results collecting collision data at the record center of mass energy of 7 TeV. Such energy is though still a factor two below the design value of the LHC. Higher beam energy will be beneficial for the physics program of the experiments. The discovery potentials for the main physics objectives will be discussed as a function of center of mass energy (7, 8, and 10 TeV) and integrated luminosity.  The experimental implications of running at higher energies and instantaneous luminosities will also be presented.
 Speaker: Bill Murray (Particle Physics-Rutherford Appleton Laboratory-STFC - Science &) Paper Slides
• 17:25 Update on calculations of max. excess resistance allowed as a function of energy for the case of prompt/semi-prompt/adjacent quenches 20'
Operating at 3.5 TeV with defective 13 kA joints is based on twofold safety: 1) it is extremely unlikely that a magnet quench will propagate to the interconnect, and even if this occurs, 2) it is extremely unlikely that the joint will burn through, assuming the measured distribution of defective joints. Above 3.5 TeV, the currents become sufficiently large to burn a defective joint, and for safety one therefore has to rely on non-quenching the joints. In this presentation I will focus on the possibility of thermal-electrical quench propagation through the bus from a quenching magnet to the interconnect. Simulations will be supported by quench propagation measurements recently performed in SM18.
 Speaker: Arjan Verweij (CERN) Paper Slides
• 17:50 Current state of copper stabilizers and methodology towards calculating risk 20'
The talk will start by reviewing the landscape: a brief mention of the results of the warm copper stabilizer measurements and the results of the splice measurements at cold will be shown. The preliminary results of the recent RRR measurements will then be presented. Then, together with the limits presented from talk no. 2, the probability of an incident will be presented for beam energies between 3.5 and 5TeV.  The available methods at our disposal for addressing the limiting factors and operating at a higher energy will then be reviewed:  a complete circuit qualification method coined the Thermal Amplifier can define the maximum safe energy of the LHC in case of a quench next to a defective joint. Ways of avoiding magnet quenches, another critical element of the analysis, for instance by optimizing BLM settings will then be shown. Finally, a proposal of a strategy for running at the highest possible energy compatible with a pre-defined level of risk will be presented. As a case study, the method will also be applied on the training campaign of sector 56, where a significant number of quenches at currents above 10,000A were seen with no adverse effects. Were we simply lucky with this training campaign?
 Speaker: Mike Koratzinos (CERN) Paper Slides
• 18:15 Implications of increased beam energy on QPS system, EE time constants, PC 15'
The operational limits given by the present configuration of the LHC Quench Protection and Energy Extraction Systems will be presented and the necessary modifications to operate with beam energies of 4, 4.5 and 5 TeV will be explained. The presentation will not only focus on changes to the hardware such as the installation of snubber capacitors for the energy extraction systems but as well on changes of detection settings e.g. for the symmetric quench detection systems. The necessity to increase the fast discharges time constants of the main circuits will be discussed. Finally the impact and status of eventual system non-conformities will be addressed.
 Speaker: Jens Steckert Paper Slides
• 18:30 Break 10'
• 18:40 What needs to be done to reach beam energy above 3.5 TeV? Commissioning of essential magnet powering and machine protection systems. 25'
After the initial plans in 2007 to run the LHC at 7 TeV, a number of unexpected events, and the extended knowledge of the machine that came after them, have convinced us to gradually reduce the beam energy to the current 3.5 TeV. As a consequence of this, some circuits have been commissioned to different energy levels.  Some systems, as the quench protection system, are working at a reduced level of accuracy based on less demanding conditions. Non-conformities that were unacceptable for higher energy have no consequences at the current energy and are thus accepted. In this talk, we will review the current status of commissioning of all the circuits and estimate the time and effort necessary to make all circuits operational at higher energies. All existing nonconformities that need to be solved before increasing the energy will be reviewed and their impact in terms of machine safety and schedule will be assessed.   The talk will try to outline a stepped energy increase compatible with the already planned maintenance periods and balanced between physics and commissioning time.
 Speaker: Dr. Nuria Catalan Lasheras (CERN) Paper Slides
• 19:10 Consequences of a hypothetical incident for different sectors 15'
During the 2009 long shutdown, the LHC machine has been partially consolidated by adding safety relief devices in order to better protect the cryostats against large helium release and consequently to mitigate the risks of collateral damage. After recalling the present relief valve implementation and other mitigations related to the collateral damage, this paper describes the damage process of a hypothetical incident, presents its consequences for the different sectors and for beam energies up to 5 TeV with emphasis on the induced downtime.

 Speaker: Laurent Jean Tavian (CERN) Paper Slides
• 19:30 Operational consequences of running at a higher energies 15'
The operational overheads of moving above 3.5 TeV are examined. This examination will look at the cost of performing such a move at the start, or during, the 2011 run. The impact of operation with beams above 3.5 TeV on machine protection systems is briefly reviewed and any potential limitations are enumerated. Finally the possible benefits of increasing the beam energy on the luminosity are discussed.
 Speaker: Mike Lamont (CERN) Paper Slides
• Wednesday, 26 January 2011
• 08:30 - 12:00 Session 05 High Intensity: Present and Future
 Conveners: Dr. Ralph Assmann (Chair), Dr. Stefano Redaelli (Scientific Secretary) Minutes
• 08:30 Beam Cleaning and Collimation: Too Bad or Too Good? 20'
The LHC collimation system intercepts unavoidable beam losses and absorbs the lost beam power. In particular, it shields the super-conducting magnets against heating from beam loss. Its performance is characterized by the leakage rate or cleaning inefficiency. The system inefficiency depends on the beam energy, the beam type (protons or ions), the collimator settings and operational imperfections. The achieved performance during the first full LHC run is presented. Operational tolerances and difficulties during the 2010 run are reviewed. Setup procedures are described and ways for faster setup discussed. Based on the observed loss rates and magnet quench limits future performance is extrapolated, in particular for the achievable store beam energy and beta*. Observations and updated limits are compared to previous predictions. Collimator settings for 2011 are proposed and associated limits and margins explained. The impact of higher beam energy is discussed.
 Speaker: Dr. Ralph Assmann (CERN) Paper Slides
• 09:00 Limits for Beam-Induced Damage: Reckless or too Cautious? 20'
Accidental events implying direct beam impacts on collimators are of the utmost importance as they may lead to serious limitations of the overall LHC Performance. In order to assess damage threshold of components impacted by high energy density beams, advanced numerical simulation methods are under continuous development. Results of analyses carried out on several Phase 1 Collimators are discussed. In particular, the number and size of proton bunches leading to catastrophic failure of a Tungsten collimator (TCT) are described in detail.

 Speaker: Alessandro Bertarelli (CERN) Paper Slides
• 09:30 Radiation to Electronics: Reality or Fata Morgana? 20'
A first year of successful LHC operation has passed reaching about 50pb-1 of integrated luminosity (1‰ of nominal, 5% of 1fb-1) and more than 1% of peak luminosity, as well as a successful ion run. It’s thus time having a first look on the observed radiation levels around LHC critical areas and to compare them to available simulation results. In spite of the still very low integrated intensities and cumulative luminosities, we will try revisiting the failure rate predictions by looking at both the observed early failures, as well as the additional results from 2010 CNRAD tests. Upcoming possibly in early 2011, electron cloud and scrubbing issues and their impact on radiation levels will also be briefly discussed. Updated predictions for 2011 operation and beyond will be deduced, on the base of the envisaged LHC intensity, energy and luminosity reach. Starting from these estimates, priorities for short-term improvements and beam tests are discussed, as well as a brief overview of upcoming R2E driven mitigation actions.
 Speaker: Markus Brugger (CERN EN/STI/EET) Paper Slides
• 10:00 Coffee break 30'
• 10:30 Radiation Protection: How (radio)active are we going to be? 20'
Operation in 2010 has caused the first components to become radioactive.  An overview of the present residual dose rates around the machine is given and compared to results of activation studies. It shows that measurable activation is presently limited to a few components only, such as collimators and absorbers. The  procedures to be applied for maintenance and repair work in the tunnel and/or workshops reflects the low radiological risk. However, the comparison to calculated residual dose rates also confirms results of studies and adds confidence in predictions for operation in 2011/12. The latter are given assuming operation at 4.5TeV with up to 100 MJ stored beam energy. At the same time, predictions by pure simulation have limitations which are outlined. In order to overcome them, assessments combined with measurements are planned and will be summarized.
Finally, the implications of the envisaged operational scenarios for 2011/12 on maintenance and consolidation work as well as on the validity of compensatory measures are detailed.
 Speaker: Stefan Roesler (CERN) Paper Slides
• 11:00 Collimator Improvements 2011 and Upgrade 2012: What Do We Plan? 20'
The LHC collimation system has provided an outstanding performance during the first year of high-intensity beam operation. The complete Phase I system was commissioned and delivered routinely a cleaning performance close to the nominal exceptions with relaxed collimator settings. On the other hand, the first commissioning experience has also provided first indications of system limitations alongside of hints for possible improvements. In particular, the expected performance limitations from losses in the cold dispersion suppressors (DSs) at either side of the warm cleaning insertions have been confirmed. While improvements of the system will already be implemented during the 2010 shutdown, the major performance limitation from the DS require a change of the machine layout that will be addresses in the 2012 long shutdown. In this papers, the proposed improvements of the system are presented. The expected gains and the implication of the proposed changes on the system re-commissioning are discussed.
 Speaker: Dr. Stefano Redaelli (CERN) Paper Slides
• 11:30 RF System: Is It Working Well Enough? 20'
The first part will review the RF setting-up and operation in 2010: From the initial RF noise concerns (April), to the need for longitudinal blow-up with the nominal bunch intensity (May), then the problems to fill the machine when increasing the number of injections  (dump triggered by secondary radiation related to capture losses).  The statistics on RF fault and their cure will also be presented.
The second part concentrates on the higher intensity and energy operation foreseen for 2011. We will discuss the improvements expected from the Longitudinal damper and the benefits and side-effects from the 1-Turn feedback .  The issue of surviving a klystron trip during physics will be studied, using both modeling and observations in 2010. Finally the settings proposed for klystrons and cavities (High Voltage, cathode current and Loaded Q) will be presented.
 Speaker: Philippe Baudrenghien (CERN) Paper Slides
• 16:30 - 17:00 Coffee Break
• 17:00 - 20:00 Session 06 Machine Protection in 2011 and beyond
The session will provide a synthesis of the experience with the commissioning and operation of the LHC machine protection system during the initial 2010 run. The focus will be on the stored energy target of 30MJ, but we will as well identifying possible show-stoppers , their necessary mitigations and try to identify a strategy to start increasing the intensity beyond the 2010/11 target, with a special emphasis on injection protection for very unsafe beam (ie >= 32 bunches).

 Conveners: Dr. Markus Zerlauth (Chair), Giulia Papotti (Scientific Secretary) slides
• 17:00 Experience with MPS during the 2010 run 20'
In 2010 the LHC stored beam energy was pushed to 25 MJ, ten times above TEVATRON, in little over 6 months. No machine protection issues were recorded, and the reliability of the machine protection system (MPS) did not impact beam operation in a significant way. After an initial phase of low intensity beam operation that was used among other things for the commissioning of the MPS, the intensity was increased in steps of a factor 2 up to 2 MJ. Following a stability run at 2 MJ, the intensity was increased in steps of around 3 MJs every few days during train operation. The intensity steps and upcoming MP issues were approved and discussed in the restricted Machine Protection Panel (MPPr) composed of representatives from the main MP sub-systems. Two reviews of the MPS were organized in 2010, one internal and one external review. This presentation will discuss the performance of the MPS, the experience from the MPPr and of the intensity increase and the outcomes of the reviews.
 Speaker: Dr. Jorg Wenninger (CERN) Paper Slides
• 17:25 Can operations put the MPS into an unsafe state? 20'
During the 2010 run, the MPS have been additionally stressed by the commissioning of operational procedures and systems tests. As requested by the MPS external review committee, human factors have to be further minimized and discipline reinforced when increasing the stored beam energies towards and beyond the 2010 target of 30 MJ. This talk will present a synthesis of the Evian discussion on MPS and human factors, with an emphasis on the tools and procedures to be put in place for the 2011 run in order to ensure the machine safety during standard beam operation and after periods of machine developments or technical stops.

 Speaker: Laurette Ponce Slides
• 17:50 Preparing MPS for 2011 run 20'
The expected performance of the Machine Protection System for 2011 is presented. An overview of the foreseen modifications to the machine protection system components during the Christmas stop and the required time for recommissioning is given. The possible impact of the MPS on the operational parameters of the LHC, like beam intensity, beta*, emittance and maximum beam energy, are discussed.
 Speaker: Dr. Jan Uythoven (CERN) Paper Slides
• 18:15 Break 10'
• 18:25 Is the BLM system ready to go to higher intensities? 20'
The higher beam intensities will enhance the effects of the beam losses observed during 2010 run. In particular beam losses due to so called UFOs are discussed, but also other beam loss phenomena like luminosity losses, injection losses and the leakage from the collimation system are considered. The current understanding of the quench limits reflected in the BLM thresholds on the cold magnets is presented. The thresholds for possible increased beam energy are reviewed.
 Speaker: Dr. Mariusz Sapinski (CERN/BE-BI) Paper Slides
• 18:50 What are the issues with injecting unsafe beam into the LHC ? 20'
Nominal LHC operation foresees to inject four batches of 72 bunches at the time. Injection of up to 32 bunches per batch has been tested in 2010 and possible intensity limitation and machine protection issues have been highlighted, in view of 2011 run. Beam leakage at LHCb and ALICE during injection and qualification of the provided protection are evaluated. Encountered and potential failures of the injection system are presented together with existing and required redundancy of the injection interlocks. Possible modifications of injection procedure and implication for filling schemes  are discussed.
 Speaker: Dr. Chiara Bracco (CERN) Paper Slides
• 19:15 Is there a limitation to the stored beam energy for 2011 and beyond? 20'
The machine protection systems have been designed to ultimately operate with beams of a stored energy of 360MJ. This presentation will address if there is an intermediate limit and what upgrades are required to permit operation with 360MJ. A failure in one of the protection systems (BLM, BIC, LBDS, …) could have catastrophic consequences for LHC. Considering the operational experience, the most critical failure modes are reviewed, their probability is estimated and methods for mitigation are discussed. Ideas for reducing the risk include additional interlocks (DIDT interlock, abort gap cleaning/monitoring, fast BLMs, additional BPMs as HW interlock, aperture measurements,…), operational procedures and upgrades of hardware systems. There are also examples when the beams should NOT be dumped immediately.
 Speaker: Mr. Rüdiger Schmidt (CERN) Slides
• 20:00 - 23:00 San Luis Street Band & Workshop dinner (les Aiglons) 3h0'  Poster
• Thursday, 27 January 2011
• 08:30 - 13:00 Session 07 Running in 2011 - Luminosity
 Conveners: Mike Lamont (Chair), Miss. Verena Kain (Scientific Secretary) paper
• 08:30 Experiments' expectations 20'
An overview of the requests from the experiments for 2011 (2012?) will be given. This will include integrated luminosity considerations, special runs and special beam conditions. Based on assumptions of achievable beam parameters, a proposal for the 2011 physics run scenario will be presented.
 Speaker: Massimiliano Ferro-Luzzi (CERN) Paper Slides
• 09:00 Pushing the limits - beam 20'
Many collective effects were observed in 2010, first when the intensity per bunch was increased and subsequently when the number of bunches was pushed up and the bunch spacing was reduced. After a brief review of the LHC performance during the 2010 run, with a particular emphasis on impedance, beam-beam and electron cloud issues, the potential of the LHC for 2011 will be discussed. More specifically, the maximum bunch/beam intensity and the maximum beam brightness the LHC should be able to swallow will be compared to what the injectors can provide.
 Speaker: Dr. Elias METRAL (CERN) Paper Slides
• 09:30 Pushing the limits: crossing angles, aperture and beta* 20'
First experiences with colliding beams at high intensities and small emittances have been collected during the 2010 LHC run. These will be critically examined and serve as input to define strategies for operation with more bunches and higher luminosities in 2011. The proposed strategies include running scenarios for proton operation in ALICE and LHCb.

 Speaker: Werner Herr (CERN) Paper Slides
• 10:00 Coffee 30'
• 10:30 Luminosity analysis 20'
The first year of LHC operation was very successful regarding the peak and integrated luminosity targets, but the luminosity lifetime could probably have been better. For this reason, the luminosity evolution during physics fills is studied and correlated to single beam lifetimes and emittance growth in order to try and understand possible causes of luminosity lifetime decrease, e.g. IBS, beam-beam related phenomena, electron-cloud and possibly the “hump”.
 Speaker: Dr. Giulia Papotti (CERN BE/OP) Paper Slides
• 11:00 Luminosity calibration 20'
The experiments do not only require high collision rates and integrated luminosity, but also an absolute normalization of the observed cross sections. This normalization can be derived from theoretical predictions or the determination of the absolute luminosity. During the 2010 proton run, the Van Der Meer scan method was used to provide a first measurement of the absolute luminosity from machine parameters. Based on the outcome of the Lumi Days workshop, future requirements, prospects and alternative methods (vertex, high beta) will be summarized.
Implications on machine operation and protection will be discussed.
 Speaker: Simon Mathieu White (Universite de Paris-Sud (Paris XI)) Paper Slides
• 11:30 Heavy Ions in 2011 and beyond 20'
The LHC's first heavy ion run set - and tested - the operational pattern for 2011 and later years: a rapid commissioning strategy intended to ensure delivery of integrated luminosity despite the risks associated with the short time-frame.  It also gave us hard data to test our understanding of the beam physics that will limit performance.
The 2010 experience is fed into the commissioning plan, parameter choices and projected performance for 2011.
The prospects for future stages of the LHC ion program, Pb-Pb collisions at higher energy and luminosity, hybrid collisions and other species, depend critically on the scheduling of certain hardware upgrades.
 Speaker: Dr. John Jowett (CERN) Paper Slides
• 12:00 Operational schedule 2011 & potential performance 20'
The assumed LHC beam parameters for 2011 are summarised. The overview of the 2011 schedule is presented and including hardware commissioning, beam re-commissioning, re-validation, scrubbing, technical stops, MD, ions and special physics run requests. A strategy for stepping up in intensity is proposed and potential issues are described together with possible actions.  Finally, the potential peak and integrated luminosity are given.
 Speaker: Malika Meddahi (CERN) Paper Slides
• 12:30 Discussion 30'
• 16:30 - 17:00 Coffee Break
• 17:00 - 19:40 Session 08 High Luminosity (HL-LHC)
 Conveners: Prof. Lucio Rossi (Chair), Riccardo De Maria (Scientific Secretary)
• 17:00 Do we really need the LHC luminosity upgrade? Or, which performance can we get without an upgrade? 25'
From what we know now, after the 1st year of LHC operation, is an upgrade (with major hardware modifications) required for improved beam performance? Will it remove bottlenecks? Will a smart new set of LHC parameters – and LHC Injector parameters - do the job? To what extent?
 Speaker: Oliver Bruning (CERN) Slides
• 17:30 Breaching the Phase I optics limitations for the HL-LHC 25'
Performance goal of the HL-LHC (5E34 for the “running” luminosity and 10E34 “potentially available” to reach it).
New optics concepts for the HL-LHC (short reminder of the Phase I optics limitations, description of the new scheme, potential in terms of beta* and beta* aspect ratio and weak points).
Following this specific path, what is still missing and the most likely additional ingredients needed to reach the goal and build margins? What can be tested now in the machine?

 Speaker: Stephane Fartoukh (CERN) Paper Slides
• 18:00 HL-LHC: parameter space, constraints and possible options. 25'
Which are the most promising ingredients to boost the LHC integrated luminosity, including smaller beta*, higher beam intensity, crab crossing, large Piwinski angle, flat longitudinal profile, and variations of bunch length, transverse emittance, crossing angle, and bunch spacing? How do the various ingredients conspire or compete? How do they pose different requirements on new LHC hardware and on the beams from the injectors?  Which is their relative importance? What are the proposed roadmap and branching points in the research for a solution?

 Speaker: Dr. Frank Zimmermann (AB/ABP) Slides
• 18:30 Break 10'
• 18:40 Expectations on Management and Performance Evolution: Lessons from Tevatron and Other Colliders. 25'
The talk will discuss the luminosity evolution of the Tevatron collider at different stages of the Collider Runs Ia, Ib and II, emphasize general dynamics of the process, analyze planned and delivered luminosity integrals, discuss the expectation management lessons, and compare with other colliders.
 Speaker: Dr. Vladimir Shiltsev (Fermilab) Paper Slides
• 19:10 Alice and LHCb in the HL-LHC era. 25'
So far all the upgrade schemes have been studied assuming only two general
purpose detectors, ATLAS and CMS, operating. Will Alice and LHCb run in HL-LHC time? When and what process to decide it? What are the beam parameters they want to exploit and the hardware changes they need in case of an upgrade?
 Speaker: Sergio Bertolucci (CERN) Slides
• Friday, 28 January 2011
• 08:30 - 10:45 Session 10 Summary
 Conveners: Steve Myers (Chair), Dr. Frank Zimmermann (Scientific Secretary)
• 08:30 Summary Session 01 : Review of 2010 Operations 10'  Speakers: Malika Meddahi (CERN), Laurette Ponce (CERN) Slides
• 08:45 Summary Session 02 -03 : Shutdown 2012 10'  Speakers: Simon Baird (CERN), Katy Foraz (CERN) Paper Slides
• 09:00 Summary Session 04 : Beam Energy 10'  Speakers: Dr. Andrzej SIEMKO (CERN), Marco Zanetti (MIT) Slides
• 09:15 Summary Session 05 : High Intensity, Present and Future 10'  Speakers: Dr. Ralph Assmann (CERN), Dr. Stefano Redaelli (CERN) Slides
• 09:30 Summary Session 06 : Machine Protection in 2011 and beyond 10'  Speakers: Dr. Markus Zerlauth (CERN), Dr. Giulia Papotti (CERN BE/OP) Slides
• 09:45 Summary Session 07 : Running in 2011 - Luminosity 10'  Speakers: Mike Lamont (CERN), Miss. Verena Kain (CERN) Slides
• 10:00 Summary Session 08 : High Luminosity (HL-LHC) 10'  Speakers: Prof. Lucio Rossi (CERN), Riccardo De Maria (CERN) Paper Slides
• 10:15 General Discussion 30'  Speakers: Steve Myers (CERN), Dr. Frank Zimmermann (AB/ABP) Slides
• 10:45 - 11:15 Coffee Break
• 11:15 - 15:50 Session 09 LHC Injectors Upgrade (LIU)
 Conveners: Roland Garoby (Chair), Malika Meddahi (Scientific Secretary) paper
• 11:15 Performance reach of the injectors in 2011 20'
The characteristics of the various LHC beams have been defined long before the LHC became operational. After a year of successful LHC running with the different types of LHC beams much experience has been gained in the LHC, but also in the injectors.
This talk will summarise the defined and presently obtained beam characteristics of the LHC beams in the injector chain together with a brief overview of their production schemes and difficulties.
Finally an outlook for 2011 will be presented, indicating the possible characteristics for the different LHC beams in the injector chain.
 Speaker: Rende Steerenberg (CERN) Paper Slides
• 11:45 Possibility of a higher PSB to PS transfer energy 20'
Following the Chamonix 2010 workshop a task force has been set up to study the feasibility and the impact of an energy upgrade of the PS Booster from the present 1.4 GeV to about 2 GeV. The working group has confirmed the feasibility of such an upgrade, and analysed in detail the impact on the accelerator hardware along with a cost estimate and a tentative planning. The outcome of the task force will be summarized, with particular emphasis on the remaining limitations, risks and uncertainties.
 Speaker: Dr. Klaus Hanke (CERN) Paper Slides
• 12:15 PS potential performance with a higher injection energy 20'
In the context of the LHC Injectors’ upgrade project, the PS has to be brought up to- and to operate reliably at- the level of performance required by the HL-LHC until the end of the LHC lifetime. The study has started of the potential benefits of increasing the injection energy. An overview of the impact of this upgrade will be presented, with a preliminary estimate of the beam characteristics at the SPS entrance and the remaining performance limitations. The necessary hardware modifications will be described, highlighting the critical systems and the risks. The program for the 2011 machine studies and hardware interventions for refining these plans will be presented.
 Speaker: Dr. Simone Gilardoni (CERN) Paper Slides
• 12:45 Buffet lunch 1h30'
• 14:15 Electron Clouds in the SPS: progress in the analysis of cures/mitigations measures and potential schedule of implementation 20'
After a brief review of the studies (simulations and measurements) made so far, a set of priorities for new studies will be presented and justified. These proposals will include all studies related to coating techniques, clearing electrodes, active feedbacks, together with their related instrumentation.
The feasibility, state-of-the-art, hard limits and opened questions, required infrastructures, schedule implications, phasing feasibility of the proposed mitigation solutions will be considered in the frame of only the upgrade of the SPS (i.e. without removing the beampipes from the magnets) and in the frame of combining the SPS upgrade with its required long-term consolidation (exchange of the magnet beampipes as an alternative).
A tentative schedule of milestones in the decision making will be presented and discussed.
 Speaker: Dr. Jose Miguel Jimenez (CERN) Paper Slides
• 14:45 Lessons from SPS studies in 2010 20'
The experimental studies done in the SPS in 2010 were devoted  both to a validation of some already proposed upgrades (such as chamber coating) and to uncovering new  limitations by pushing up the injected bunch intensity.
The first results obtained for higher than nominal intensity LHC beam with 25 ns and 50 ns bunch spacing, each beam available during only one MD session in the SPS, will be presented together with results for a single high intensity bunch.
The limitations encountered during these MD studies will be discussed together with other SPS bottlenecks. Possible cures and mitigations will be revisited as well as present achievements.
An option for improving the beam stability in the SPS, opened up again by the successful demonstration  of reducing the SPS transition energy, will also be discussed.
The potential for delivering bunches with small transverse emittances now and after upgrades will be analyzed. An attempt will be made at summarizing the accessible range of beam parameters (intensity per bunch as a function of distance between bunches and emittance).
 Speaker: Elena Shaposhnikova Paper Slides
• 15:15 Alternative / complementary possibilities 20'
Generation of higher brightness LHC bunch trains in the PS with RF gymnastics different from the present scheme has been studied.  With Linac4 and exploiting the beam of all four PSB rings to fill most of the PS circumference allows bringing the PS close to the direct space charge limit with one injection.  Batch compression after acceleration to an appropriate intermediate energy allows increasing the beam brightness at the price of reducing slightly the number of bunches per PS batch. Potential beam characteristics at PS ejection have been estimated, with and without an increase of the PSB to PS transfer energy, and with a single or a double batch injection. The impact of shorter bunch trains on the downstream accelerators has also been analyzed. These new schemes are presented together with their expected benefits. The beam experiments required to reduce the uncertainties and prepare a well-founded upgrade proposal are described.
 Speaker: Christian Carli (CERN) Animation Paper Slides
• 15:50 - 16:00 Closing remarks 10'  Speaker: Steve Myers (CERN) Slides