# LHC Performance Workshop - Chamonix 2012

from to (Europe/Zurich)
at Chamonix
 Support Email: acctdir@cern.ch
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• Monday, 6 February 2012
• 08:30 - 12:30 S01 - Lessons from 2011  Conveners: Mike Lamont (Chair), Chiara Bracco (Scientific Secretary) Material:
• 08:30 Chamonix 2012 welcome 5'  Speaker: Steve myers Material:
• 08:35 Review of 2011 LHC run from the experiments perspective 10'
The 2011 LHC run is reviewed from the experiments perspective. The achievements directly related to physics production are summarized. This includes high luminosity p-p and Pb-Pb running, special activities (such as intermediate energy p-p physics, 90 m optics, luminosity calibrations) and other experiments (for example satellite-main bunch collisions in IP2, 25 ns stable beams tests, etc.).

 Speaker: Massimiliano Ferro-Luzzi (CERN) Material:
• 08:45 Input from Evian 20'
The LHC Beam Operation workshop 2011 took place 12th - 14th December. The principle aims of the workshop were to review 2011 LHC beam commissioning and beam operations experience, and to look forward to the operation of the LHC in 2012. Issues covered include: availability; injection; operational performance; beam loss and machine protection;system performance; limitations; and the outlook for 2012.

A concise summary of the workshop is presented and potential performance issues for 2012 are highlighted. Where material is covered in more depth here at Chamonix appropriate reference will be made.
 Speaker: Mike Lamont (CERN) Material: Paper
• 09:05 2011 availability analysis 20'
A critical evaluation of machine availability and performance analysis of the 2011 Run will be given. This will include both an analysis of the run in terms of  the different operational modes, as well as a breakdown of the run in terms of downtime and faults. Detailed evaluation of systems with significant fault time will be addressed, and intended improvements discussed. In addition a survey of premature dump statistics will be presented, along with a summary of the implemented improvements and their effect on overall performance in the 2011 run.
 Speaker: Alick Macpherson (CERN) Material:
• 09:25 Injection and lessons for 2012 20'
Injection of 144 bunches into the LHC became fully operational during the 2011 run and a nominal injection of 288 bunches was accomplished during MD time. Several mitigation solutions were put in place to minimise losses from the transfer line (TL) collimators and losses from kicking debunched beam during injection.  Nevertheless, shot-by-shot and bunch-by-bunch trajectory variations, as well as long terms drifts, were observed and required a regular resteering of the TL implying a non negligible amount of time spent for injection setup.  Likely sources of instability have been identified (i.e. MKE and MSE ripples) and possible cures to optimise 2012 operation are presented.  Well defined references for TL steering will be defined in a more rigorous way in order to allow a more straightforward and faster injection setup. Benefits from an improved transverse beam diagnostic in the injectors (emittance, beam distribution and tail population) are illustrated.
Encountered and potential issues of the injection system, in particular the injection kickers MKI, are discussed also in view of injections with a higher number of bunches.

 Speaker: Chiara Bracco (CERN) Material:
• 09:45 Coffee break 20'
• 10:05 Machine Protection 20'
The performance and experience with the LHC machine protection system during the 2011 run will be briefly summarized. Emphasis will be given to identify further potential improvements of the existing protection systems for the 2012 run alongside possibilities to allow for a more efficient strategy during the intensity ramp up whilst maintaining the required validation steps and dependability for the various machine protection elements. The role of machine protection during the 2011 MD periods and special runs will be summarized.
 Speaker: Markus Zerlauth (CERN) Material:
• 10:25 Vacuum performance and lessons for 2012 20'
During the LHC run 2011, a tremendous progress has been made towards the machine operation with design parameters. In the same time, the run confirmed the sensitivity of the beam vacuum system to the machine parameters. As expected, a successful scrubbing period allowed mitigating the effects of the electron cloud giving room to an entire filling of the ring with 50 ns beams. In parallel issues such as the impact of the beam screen regulation, pressures spikes and local outgassing were observed during the year. On-line mitigations and immediate compensatory measures implemented during the winter technical stop are reviewed together with their efficiencies. The expected limitations while waiting for LS1 consolidation or when running with 25 ns beams are addressed. Lessons for 2012 are discussed.
 Speaker: Vincent Baglin (CERN) Material:
• 10:45 Emittance preservation 20'
Emittance measurements during the LHC proton run 2011 indicated a blow-up of 20 % to 30 % from LHC injection to collisions. This presentation will show the emittance preservation throughout the different parts of the LHC cycle and discuss the current limitations on emittance determination. An overview of emittance preservation through the injector complex as function of bunch intensity will also be given. Possible sources for the observed blow-up and required tests in 2012 will be presented. Possible improvements of emittance diagnostics and analysis tools for 2012 will be shown.
 Speaker: Verena Kain (CERN) Material:
• 16:30 - 17:00 Coffee break
• 17:00 - 20:30 S02 - Machine Studies  Conveners: Ralph Wolfgang Assmann (Chair), Giulia Papotti (Scientific Secretary) Material:
• 17:00 LHC experience with different bunch spacings in 2011 (25 , 50 & 75 ns) 20'
LHC operation in 2011 had a smooth start in March with 75ns beams and only one month later moved to 50ns beam, after a successful dedicated scrubbing run. Several observables, such as pressure rise, heat load in the arcs, beam instability, emittance growth and synchronous phase shift, clearly pointed to the presence of an electron cloud inside the machine during the first days of operation with 50ns beams. The gradual reduction of all these effects, and their eventual disappearance, over the days of the scrubbing run, indicated electron cloud mitigation and allowed physics production to shift to 50ns beams. Up to the end of the run the quality of the 50ns beams was increased by regular stages (first lower transverse emittances, then higher intensities) and they could provide steadily improving peak luminosities. Furthermore, 4 MD sessions with 25ns beams took place fin the period June-October, but the quality of these beams was always deteriorated by severe electron cloud effects. However, a clear improvement was noticed also with the 25ns runs. An estimation of the present state of conditioning of the machine and the required scrubbing time can be inferred from electron cloud simulations compared with measured data.
 Speaker: Giovanni Rumolo (CERN) Material: Slides
• 17:30 Observations of beam-beam effects in MDs in 2011 20'
We report the observations of beam-beam effects made in MD sessions in 2011.
The results are compared with the expectations and possible implications for the operation in 2012 are discussed.
 Speaker: Werner Herr (CERN) Material:
• 18:00 Beam-induced heating/bunch length/RF and lessons for 2012 20'
The observations made in 2011 are first compared to expectations and the possible implications for the operation in 2012 are then discussed.
 Speaker: Elias Metral (CERN) Material:
• 18:30 Lessons in beam diagnostics 20'
This presentation will concentrate on the studies carried out on LHC beam instrumentation systems during the 2011 run, the improvements made and the outlook for 2012. It will include an update on the issues resolved since 2010, such as the performance of the BCT systems, and discuss advances in the bunch by bunch measurement capability of many systems. The conclusions will highlight what can be hoped for in terms of performance for 2012 and the issues which remain to be solved.
 Speaker: Rhodri Jones (CERN) Material:
• 19:00 Quench margins 20'
With thirteen beam induced quenches and numerous Machine Development tests the current knowledge of LHC magnets quench limits still contains a lot of unknowns. Various approaches to determine the quench limits are reviewed and results of the tests are presented. Attempt to reconstruct a coherent picture emerging from these reults is taken. The available methods of computation of the quench levels are presented together with dedicated particle shower simulations which are necessary to understand the tests. The future experiments, needed to reach better understanding of quench limits as well as limits for the machine operation are investigated. The possible strategies to set BLM thresholds are discussed.
 Speaker: Mariusz Gracjan Sapinski (CERN) Material:
• 19:30 First demonstration with beam of the Achromatic Telescopic Squeeze (ATS) 20'
The Achromatic Telescopic Squeezing (ATS) scheme is a novel squeezing mechanism, which is (almost fully) compatible with the existing hardware of the LHC, and enables both the production and the chromatic correction of very low  beta*. The basic principles of the ATS scheme will be reminded together with its basic motivation which is to deliver a very ambitious beta* of 10-15 cm in view of the even more ambitious performance commitments taken by the HL-LHC project. In this context, a few dedicated beam experiments were meticulously prepared and took place at the LHC in 2011. The results obtained will be highlighted, demonstrating already the viability of the scheme. The plans for 2012 will be discussed, with a few optics considerations which could already justify the implementation of the ATS scheme in the nominal machine, depending on which beta* limits will be met first, and that the ATS can solve (e.g. optics matchability, chromatic aberrations) and obviously cannot: the aperture of the existing triplet.
 Speaker: Stephane Fartoukh (CERN) Material:
• Tuesday, 7 February 2012
• 08:30 - 12:30 S03 - Strategy for 2012 (I)  Conveners: Jorg Wenninger (Chair), Rogelio Tomas Garcia (Scientific Secretary) Material:
• 08:30 Experiments expectations, plans and constraints 20'
The talk discusses the input from the experiments that is relevant to define next year's program.
It covers the target for integrated luminosity for 2012, for both p-p and Heavy Ion physics, the configuration for the Heavy Ion period (p-Pb, Pb-Pb or both) and the requests for special runs (high beta, VdM scan with un-squeezed beam, high or low pile-up runs…).
The impact of LHC parameters and conditions on the experiments is also discussed, including the effect of pile-up (would experiment performance be limited next year with 50 ns?), beam energy, bunch length, vacuum and background, etc..
Proposals for optimizations will also be discussed, including the use of satellite-main collision to provide luminosity for ALICE and suggestions for reducing the overhead of ALICE and LHCb polarity reversals.

 Speaker: Benedetto Gorini (CERN) Material:
• 09:00 Turn-around improvements 20'
An efficient turnaround will be an important parameter for the integrated luminosity performance at LHC in 2012, when an operation with steady beam parameters will be achieved at the beginning early on in the run. Improvements of the operational cycle were already put successfully in place after the 2010 experience but additional improvements are possible. In this paper, the 2011 turnaround performance is reviewed and the benefits of the improvements from 2010 are presented. Possible further gains are proposed for 2012.
 Speaker: Stefano Redaelli (CERN) Material:
• 09:30 Performance reach of the injector complex 20'
At the start of the 2011 physics run quite some margins in the performance of the injectors were available and identified. Following the fast increase of the performance of the LHC itself during 2011, these margins have very much been exploited and some have even been pushed further.

In view of further increase in the LHC luminosity, the 2012 performance reach of the injectors will be reviewed. One of the arising topics is satellite bunches from the injectors. Until now concerted effort went into supressing satellite bunches to a minimum, but a recent successful test with “controlled” satellites might make their routine production and characterisation an important topic in 2012.

 Speaker: Rende Steerenberg (CERN) Material:
• 10:00 Coffee break 30'
• 10:30 Running the RF at higher beam energy and intensity 20'
The improvements done to the RF parameters and hardware in 2011 are reviewed. We then present the upgrades planned for 2012: Further reduction of capture losses with the longitudinal damper, batch per batch blow-up at injection and modification of the blow-up to preserve bunch profile. Operation at higher energy is readily possible with the present RF power, and does not degrade longitudinal stability thanks to the controlled longitudinal emittance growth during the ramp. For operation with higher beam current, the observations in 2011 indicate that there is no single bunch issue with up to 3E11 p per bunch. With the large gain of the RF feedback and One-Turn feedback, the cavity impedance at the fundamental will not be a limitation for ultimate intensity (1.7E11 p per bunch) with 25 ns spacing.  The klystron power (300 kW RF at saturation) is sufficient for 25 ns operation with nominal intensity (2808 bunches per beam, 1.1E11 p per bunch).  An RF roadmap for going beyond will be outlined: It calls for an upgrade of the LLRF only and should allow for operation with ultimate beam intensity (25 ns spacing, 2808 b, 1.7E11 p per bunch) after LS1.
 Speaker: Philippe Baudrenghien (CERN) Material:
• 11:00 Transverse damper 20'
Plans for the operation of the transverse damper in 2012 at bunch spacings of 50 ns and 25 ns and at increased collision energy will be reviewed. The increased energy and the experience that will be gained at 25 ns are very important to define any upgrades that may be necessary for the high luminosity operation at 7 TeV after LS1. This means that the available parameter space must be probed in 2012 which in particular includes a higher feedback gain in the ramp and with colliding beams. Limits for the feedback gain for the current system will be outlined. The potential benefits of running with higher feedback gain for a better emittance preservation will be stressed and weighed against the operational difficulties and the potential impact of noise in the damper system. A plan for re-commissiong at 50 ns and 25 ns for operation at 4 TeV will be outlined.
 Speaker: Wolfgang Hofle (CERN) Material:
• 11:30 R2E failure rates expectations 20'
2011 very successful LHC operation has provided valuable input for the detailed analysis of radiation levels and radiation induced equipment failures. Radiation levels around LHC critical areas and the LHC tunnel were studied in detail and compared to available simulation results, as well as put in perspective to LHC operation parameters. Observed radiation induced failures were not only analyzed in detail, but already addressed through early relocation measures and patch-solution on the equipment level. Both improvements continue during this xMasBreak together with the installation of heavy shielding around the RBs and UJs in Point-1. Based on measured radiation levels, calculations for the shielding improvements and expected operational parameters this talk provides an update on the expected radiation levels around LHC critical areas. Briefly summarizing the already performed mitigation measures and equipment patches, an estimate is provided on expected equipment failure rates during 2012 operation. Required beam and measurement studies are highlighted in order to further improve the predictions of both radiation levels and expected equipment failures, the latter driving the chosen mitigation actions for LS1.

 Speaker: Markus Brugger (CERN) Material:
• 16:30 - 17:00 Coffee break
• 17:00 - 20:30 S04 - Strategy for 2012 (II)  Conveners: Oliver Bruning (Chair), Laurette Ponce (Scientific Secretary) Material:
• 17:00 Beam Energy 20'
The limiting factors for operating the LHC at higher energies with defective 13 kA busbar joints will be reviewed. The experience gained during the 2011 run, including the quench statistics and dedicated quench propagation tests will be presented. The possible operational limits from the by-pass diode contact resistance issue will be addressed. Finally, a proposal for running at the highest possible safe energy compatible with the pre-defined risk level will be presented.
 Speaker: Andrzej Siemko (CERN) Material:
• 17:30 Optics Options 20'
The experience from the past LHC proton run has provided plenty of information and can be used to define possible scenarios for the 2012 physics run. The key parameters such as beta* and crossing angle will be reviewed assuming a 4 TeV beam energy and considering options for 25 ns and 50 ns. Possible scenarios for the high-beta optics configuration during the 2012 run will be presented.
 Speaker: Massimo Giovannozzi (CERN) Material: Slides
• 18:00 Collimation settings and performance 20'
Collimator settings and available aperture are key parameters for deciding the reach in beta*. Based on MDs and operational experience in 2011, a review is given of the measured aperture and the achievable margins and settings of the collimators. In particular, the tight collimation scheme is evaluated in terms of possible gains and necessary operational changes.
 Speaker: Roderik Bruce (CERN) Material:
• 18:30 Performance Reach in the LHC for 2012 20'
Based on the 2011 experience and Machine Development study results the performance reach of the of the LHC with 25 and 50 ns beams will be addressed for operation at 3.5 and 4 TeV. The possible scrubbing scenarios and potential intensity limitations resulting from vacuum, heating will be taken into account wherever possible.
 Speaker: Gianluigi Arduini (CERN) Material: Slides
• 19:00 MD plans in 2012 20'
Machine development sessions were performed in 2011 during dedicated slots of beam time. These MD studies were scheduled and planned in detail well before, reflecting the agreed priorities: further optimizing machine performance, exploring beam parameters beyond design targets, assessing machine limitations, testing new concepts and machine settings. The MD's in 2012 will build on the successful 2011 experience. The proposed priorities are discussed. A particular emphasis is put on how to best prepare future LHC running in view of the upcoming LHC shutdown in 2013/14 and the recommissioning of the LHC with double beam energy and nominal luminosity by 2014/15.
 Speaker: Ralph Wolfgang Assmann (CERN) Material:
• 19:30 Ions in 2012 20'
Review of the options for the heavy ion run in 2012:  proton-lead or lead-lead or time-sharing between the two.   The implications of running at special energies choice of bunch spacing and filling scheme.  Performance expectations in the light of the first p-Pb test, further MD on p-Pb and the 2011 Pb-Pb run.  Possibilities for future improvements and an outline of the programme between LS1 and LS3.
 Speaker: John Jowett (CERN) Material:
• Wednesday, 8 February 2012
• 08:30 - 12:20 S05 - LS1 (I)  Conveners: Frederick Bordry (Chair), Katy Foraz (CERN) Material:
• 08:30 LS1 general planning and strategy for LHC, LHC injectors 20'
The goal of Long Shutdown 1 is to perform the full maintenance of equipment, and the necessary consolidation and upgrade activities in order to ensure reliable LHC operation at nominal performance from mid 2014.
Long Shutdown 1 concerns not only LHC but also its injectors. In order to ensure that resources will be available an analysis is in progress to detect conflict/overload and to decide what is compulsory, what we can afford and what we have to postpone to Long Shutdown 2. The strategy, time key drivers, constraints and draft schedule will be presented.
 Speaker: Katy Foraz (CERN) Material:
• 09:00 Powering tests before LHC warm-up: What is new from Chamonix 2011? 20'
At the end of 2012, the Large Hadron Collider will enter its first programmed long stop (LS1). The problem at the origin of 2008 incident will be definitely treated and the main circuits will then be able to run at the design current value without protection issues. At Chamonix 2011, a proposal was done for a series of powering tests to be performed just before the LS1 to investigate other potential limitations in the machine, which could be fixed during the same maintenance period. A review of these powering tests is presented, together with the list of investigation to be performed by the electrical quality assurance (ElQA) team.  A tentative planning is as well proposed.
Moreover, following complementary activities during the LS1, a huge campaign of individual system tests will have to be as well performed during the shutdown. Attention will be put on the preliminary list of needed re-qualifications.
 Speaker: Mirko Pojer (CERN) Material:
• 09:30 LHC consolidation of the superconducting circuits 40'
All the activities necessary to consolidate the LHC superconducting circuits are given, especially the consolidation of the main splices, exchange of weak cryomagnets, the consolidation of the DFBAs and the special interventions. For each of them, the baseline strategy will be presented, highlighting the reasons that lead to these choices and the remaining risk level.
In particular, the progress of the work of the LHC splices task force, the recommendations of the second LHC splices review (November 2011) and their analysis are reported. Finally, the work planning, the organization chart and the associated resources will be detailed. 
 Speaker: Jean-Philippe Tock (CERN) Material: Paper
• 10:20 Coffee break 30'
• 10:50 R2E strategy and activities during LS1 20'
The level of flux of hadrons with energy in the multi MeV range expected from the collimation system at Point 7 and from the collisions at the interaction Points 1, 5 and 8 will induce Single Event Errors (SEE) of the standard electronics present in equipment located around these Points. Such events would perturb the LHC operation. As a consequence, the sensitive equipment will be shielded or relocated in safer areas.
These mitigations activities will be performed mainly during the LS1. About 15 groups (including equipment owners) will be involved. Some of them will have to work in parallel in several Points. This talk summarizes the planning of these mitigations activities in each impacted points. It presents the R2E organization process, the priorities and possible bottlenecks as today identified.
 Speaker: Anne-Laure Perrot (CERN) Material:
The last two years of LHC operation have highlighted concerns on the levels of the dynamic vacuum in the long straight sections (LSS) in presence of high intensity beams. The analysis of the existing data has shown relationship between pressures spikes and beam screen temperature oscillations or micro-sparking in the RF fingers of the bellows on one side and coincidence of pressure bumps with stimulated desorption by electron cloud, beam losses and/or thermal out gassing stimulated by HOM losses.
The electron cloud mitigation solutions will be adapted to the different configurations: cold/warm transitions, non-coated surfaces in direct view of beams, photoelectrons, etc. All scenarios will be presented together with their efficiencies. Additional pumping and reengineering of components will reduce the sensitivity of the vacuum system to beam losses or HOM inducing out gassing. The expected margin at nominal intensity and energy resulting from these consolidations will be summarized.
Finally, the challenges of the Experimental areas will be addressed, more specifically the status of the new Beryllium pipes (ATLAS and CMS) which are in the critical path and the consolidation of vacuum instrumentation, pumping and electron cloud mitigation. The risk corresponding to the proposed consolidations will be shown and the margins with respect to the schedule analyzed.
 Speaker: Jose Miguel Jimenez (CERN) Material: Slides
• 11:50 Cryogenics system: strategy to achieve nominal performance and reliable operation 30'
During the LHC operation in 2010 and 2011, the cryogenic system has achieved an availability level fulfilling the overall requirement. To reach this level, the cryogenic system has profited like many other beam-dependent systems from the reduced beam parameters. Therefore, impacts of some failures occurred during the LHC operation were mitigated by using the overcapacity margin, the existing built-in redundancy in between adjacent sector cryogenic plants and the “cannibalization” of spares on two idle cryogenic plants. These two first years of operation were also crucial to identify the weaknesses of the present cryogenic maintenance plan and new issues like SEUs. After the LS1, nominal beam parameters are expected and the mitigated measures will be less effective or not applicable at all. Consequently, a consolidation plan to improve the MTBF and the MTTR of the LHC cryogenic system is under definition. Concerning shutdown periods, the present cryogenic sectorization imposes some restrictions in the type of interventions (e.g. cryo-magnet removal) which can be done without affecting the operating conditions of the adjacent sector. This creates additional constrains and possible extra down-time in the schedule of the shutdowns including the hardware commissioning.
This presentation focuses on the consolidation plan foreseen during the LS1 to improve the performance of the LHC cryogenic system in terms of availability and sectorization.
 Speaker: Laurent Tavian (CERN) Material:
• 16:30 - 17:00 coffee break
• 17:00 - 20:30 S06 - LSI (II)  Conveners: Frederick Bordry (Chair), Katy Foraz (scientific secretary)
• 17:00 LHC experiments upgrade and maintenance 15'
All experiments plan an effective usage of the LS1 shutdown period. After three years of running they will go through a consolidation phase, mostly to fix problems which have emerged over time, like single points of failure in the infrastructure, failures of low voltage power supplies and optical links.
Upgrade of some detector components will start, manly related to the beam pipe, the innermost tracker elements and the trigger system. Detector components, which had to be staged for cost reason in 2003, will then enter into the detector setup.  The goal is to be fully ready for the new energy regime at nominal luminosity.

 Speaker: Marzio Nessi (CERN) Material:
• 17:25 QPS upgrade and machine protection during LS1 15'
The presentation will explain all the proposed changes and discuss the impact on other shutdown activities.
The upgrade of the LHC Quench Protection System QPS during LS1 with respect to radiation to electronics will concern the re-location of equipment and installation of new radiation tolerant hardware. The midterm plan for further R2E upgrades will be addressed.
The protection systems for insertion region magnets and inner triplets will be equipped with a dedicated bus-bar splice supervision including some additional modifications in order to improve the EMC immunity.
The extension of the supervision capabilities of the QPS will concern the quench heater circuits, the earth voltage feelers and some tools to ease the system maintenance. The protection of the undulators will be revised in order to allow more transparent operation.
The installation of snubber capacitors and arc chambers for the main quad circuits will be complete the upgrade of the energy extraction systems.
Finally the re-commissioning of the protection systems prior to the powering tests will be addressed. 
 Speaker: Reiner Denz (CERN) Material:
• 17:50 EN-EL upgrade and consolidation 15'
EN/EL will have a huge program of work during LS1. All our projects are being organised in order to concentrate efforts for LS1 on tasks possible only during shutdowns of the machines. Therefore the EL program for the shutdown will commence early (January 2012) and will be completed later (2015). EN/EL is now starting to increase engineering resources so that newcomers will have at least a minimum period of time for training and integration. The scale of this increase in resources will be limited by the reasonable capacity of EN/EL core staff to manage it. In other words, not all the requested activities will be possible and prioritisation will be necessary.
Three different types of activities are planned and will be prioritized for the next long shut down:
- accelerators infrastructure maintenance,
- consolidation of aging elements of EN/EL infrastructure (part of a 15 years program to substantially increase the reliability and availability of the power distribution network).
- user requests (EN/EL estimates that only 50% of the LS1 requests are currently known). The main activities will be the contributions to the R2E project, the BE/BI upgrade projects and the RF upgrade project in SPS (BA3).
 Speaker: Francois Duval (CERN) Material:
• 18:10 EN-CV upgrade and consolidation 15'
The EN/CV group will be heavily involved into  several projects and activities during LS1 within a window frame limited to around twelve months. According to the requests received so far, the majority of projects are related to the upgrade of user’s equipment, consolidation work and construction of new plants; however a part of them is needed following the experience on the first years of LHC run or to adapt the installations to new operating parameters. The author shall focus his presentation on some of these projects, outlining the impact that they will have in  operational working conditions or in the risk for breakdown.
 Speaker: Mauro Nonis (CERN) Material: Slides
• 18:35 Access strategy in the accelerator complex and experimental areas 15'
This paper shall review the main features of the new PS Personnel Protection System (PSPSS) as well as the main milestones for its deployment during the Long Shutdown of 2013-2014. Access conditions in the PS, SPS and LHC complexes during this period shall be described as well as the upgrades and improvements that are under preparation.
 Speaker: Rui Nunes (CERN) Material:
• 19:00 RF upgrade program in LHC injectors and LHC machine 20'
The main themes of the presently on-going RF upgrade program are: the LLRF-upgrade for PSB and PS, the study of a tuning-free wide-band system for PSB, the upgrade of the SPS 800 MHz amplifiers and beam controls and the upgrade of the transverse dampers of the LHC. Whilst LHC Splice Consolidation is certainly the top priority for LS1, some necessary RF consolidation and upgrade is necessary to assure the LHC performance for the next 3-year run period. This includes 1) necessary maintenance and consolidation work that could not fit the shorter technical stops during the last years, 2) the upgrade of the SPS 200 MHz system from presently 4 to 6 cavities, which constitutes the present bottle neck for LHC beam current and possibly 3) the replacement of one LHC cavity. On the longer term, the LHC luminosity upgrade requires crab cavities, for which some preparatory work both in SPS Coldex and LHC point 4 must be scheduled during LS1.
 Speaker: Erk Jensen (CERN) Material:
• 19:30 What is the maximum reasonable energy? 20'
In 2008 all the LHC main dipole circuits were trained to 5 TeV, two sectors to 6 TeV, and one sector was pushed up to 6.6 TeV. In the 5-6 TeV range, a few quenches were needed to retrain the LHC dipoles, and none for the quadrupoles. On the other hand, in the 6-7 TeV range a larger than expected number of quenches was observed in the main dipoles. Using this limited set of data, tentative estimates were given to guess the number of quenches needed to reach nominal energy.  After three years, the only additional experimental data are the retraining of the magnets individually tested at SM18, either coming from the spares or from the 3-4 sector.  After presenting this additional information, we will consider the different scenarios that can be envisaged to train the LHC main magnets after the Long Shut-down 1, the expected energy, the impact on the commissioning time and the associated risk.
 Speaker: Ezio Todesco (CERN) Material:
• Thursday, 9 February 2012
• 08:30 - 12:30 S07 - After LS1  Conveners: Rudiger Schmidt (Chair), Mirko Pojer (Scientific Secretary)
• 08:30 Performance potential of the injectors after LS1 20'
The main upgrades of the injector chain in the framework of the LIU project will only be implemented in the second long shutdown (LS2), in particular the increase of the PSB energy to 2 GeV or the implementation of cures/solutions against instabilities/e-cloud effects etc. On the other hand, Linac4 will become available by the end of LS1. Its connection to the PSB can then take place either on short notice if Linac2 fails, taking 50 MeV protons in the PSB via the existing injection system but with reduced performance, or from the end of 2015 during a prolonged winter shutdown before LS2. The anticipated beam performance of the LHC injectors after LS1 in these different cases is presented. Space charge on the PS flat-bottom will remain a limitation because the PSB to PS transfer energy will stay at 1.4 GeV. Therefore new RF manipulations are presented which will improve brightness for 25 ns bunch spacing and should allow for more than nominal luminosity in the LHC.

 Speaker: Heiko Damerau (CERN) Material:
• 08:55 Performance reach of LHC after LS1 20'
Based on past experience (2010/2011), in particular expected limitations from beam-beam effects, and taking into account the expected beam quality from the LHC injectors, the peak and integrated luminosities at top energy are discussed for different scenarios (e.g. bunch spacing, beta*). In particular it will be shown which are the key parameters to reach the nominal luminosity and whether it is possible to exceed the nominal luminosity. Possible test in 2012 are discussed.
 Speaker: Werner Herr (CERN) Material:
• 09:20 Magnet powering with zero downtime - a dream? 20'
Despite a number of improvements already applied in the course of the year, the magnet powering system of the LHC still accounts for around 50% of the premature beam dumps. This number might even further increase when moving to higher beam energies in the next years. With mitigations of radiation effects and the prospects for beam induced magnet quenches being discussed elsewhere, we aim at identifying possible mid- and long-term improvements within the various equipment systems to further reduce the number of equipment failures leading to a loss of the particle beams. Amongst others, this includes the sensitivity of equipment to external causes such as electromagnetic perturbations or perturbations on the electrical network. To conclude, the gain of the identified mitigations will have to be balanced against the potential impact on schedule and cost.
 Speaker: Markus Zerlauth (CERN) Material:
• 09:45 Beam systems without failures – what can be done? 20'
The beam dumps triggered by interlocks not related to the magnet powering are discussed. This  concerns the systems like the RF, the transverse feedbacks, beam instrumentation, beam dumping system, collimators and control systems. An analysis of the reasons of these dumps is presented together with a possible strategy to mitigate the effect of these failures.
 Speakers: Matteo Solfaroli Camillocci (CERN), Jan Uythoven (CERN) Material:
• 10:10 Coffee break 30'
• 10:40 Will we still see SEEs? 20'
The actions during the first years of the R2E Mitigation Project allowed to drastically reducing the rate of Single Event Errors on radiation sensitive electronic equipment installed in the LHC underground areas. Shielding and relocation activities during LS1 will allow the resolution of the present issues concerning UJs of P1, 5 and 7 as well as the P8 cavern. The parallel development of radiation tolerant power converters will address the remaining concerns in the RRs. Radiation levels in areas where luminosity is the source are under control. The remaining open questions are related to the evolution of the beam-gas source term in the arc and in the dispersion suppressor and to the evolution of losses at the betatron and momentum insertion regions. 2012 operation will allow addressing these points, which will be used for a complete forecast of radiation levels and projected failures after the resume of operation in 2014/15.

 Speaker: Marco Calviani (CERN) Material:
• 11:05 UFOs – will they take over? 20'
During UFOs are one of the major unexpected performance limitations of the LHC. With large-scale increases of the BLM thresholds, their impact on LHC availability could be mitigated in the second half of 2011. For higher beam energy and lower magnet quench limits, the problem is expected to be considerably worse, though. Therefore, in 2011, the diagnostics for UFO events were significantly improved, dedicated experiments and measurements in the LHC and in the laboratory were made and complemented by FLUKA simulations and theoretical studies. In this talk, the state of knowledge is summarized and extrapolations for LHC operation after LS1 are presented. Mitigation strategies are proposed and related tests and measures for 2012 are specified.
 Speaker: Tobias Baer (CERN/Hamburg University (DE)) Material:
• 11:30 Quenches: will there be any? 20'
Quenches in superconducting circuits are part of the normal operation of the LHC, and can never be excluded. Operation at 3.5 TeV resulted in only a small amount of quenches in 2011, especially because most magnets were operated below 20% of the critical current, resulting in a temperature margin of about 5 K. When operating at about 6.5-7 TeV beam energy, the temperature margin will only be about 1.5 K and the magnets will be much more sensitive to beam losses, while at the same time the beam intensity will be higher. In this talk I will discuss the quench sensitivity of the magnets due to beam losses. I will also present the probability of increased quenching of the superconducting circuits due to other effects such as higher currents and ramp rates, increased EM coupling, and in some cases reduced QPS thresholds.
 Speaker: Arjan Verweij (CERN) Material:
• 15:30 - 16:00 Coffee break
• 16:00 - 17:00 Special Seminar - Mikhail Lomonosov 1h0'  Speaker: Vladimir Shiltsev (Fermilab) Material:
• 17:00 - 20:00 S08 -LHC-related projects and studies part (I)  Conveners: Roland Garoby (Chair), Laurette Ponce (Scientific Secretary) Material:
• 17:00 Will ALICE be running during the HL-LHC era? 10'
We will present the perspectives for ion running in the HL-LHC era.
In particular, ALICE is preparing a significant upgrade of its rate capabilities and further extending its particle identification potential. This paves the way for heavy ion physics at unprecedented luminosities, which are expected in the HL-LHC era with the heaviest ions. The potential interest of data-taking during high luminosity proton runs for ATLAS and CMS will also be commented.
 Speaker: Johannes Wessels (Westfaelische Wilhelms-Universitaet Muenster (DE)) Material:
• 17:15 Will LHCb be running during the HL-LHC era? 10'
The LHCb collaboration submitted in March 2011 a 'Letter of Intent' for upgrading the detector by 2018, in order to take data at a luminosity of 1-2x10^33/cm^2/s after LS2 with a detector read out at 40 MHz. A more flexible software-based triggering strategy will allow to increase trigger efficiencies especially in decays to hadronic final states. LHCb intends to take data for another 10 years after LS2 in parallel to ATLAS and CMS, aiming at a integrated luminosity of at least 50 fb-1. We plan to take data with 25ns bunch spacing and to use luminosity leveling, as done at present. After a short physics motivation the talk will review the desired running conditions of LHCb and other machine related requirements.
 Speaker: Burkhard Schmidt (CERN) Material:
• 17:30 HL-LHC operation with protons and ions 20'
The presentation discusses potential variations of the beam and optics parameters that are compatible with the HL-LHC design goals and attempts to discuss the parameter margins required for translating the HL-LHC performance parameters to specifications for the LHC injector complex. The variations of the parameter sets attempt to incorporate the experience from the LHC operation and MD studies in 2010 and 2011. Particular attention will be given to a comparison of the 25ns and 50ns bunch spacing scenarios for the proton beam operation. Preliminary information will be given about the modes of operation and beam parameters for ions. The impact of operation for ions during the HL-LHC exploitation period will be outlined.
 Speaker: Oliver Bruning (CERN) Material: Paper Slides
• 18:00 Can the proton injectors meet the HL-LHC requirements after LS2? 20'
The LIU project has as mandate the upgrade of the LHC injector chain to match the requirements of HL-LHC. The present planning assumes that the upgrade work will be completed in LS2, for commissioning in the following operational year. The known limitations in the different injectors are described, together with the various upgrades planned to improve the performance. The expected performance reach after the upgrade with 25 and 50 ns beams is examined. The project planning is discussed in view of the present LS1 and LS2 planning. The main unresolved questions and associated decision points are presented, and the key issues to be addressed by the end of 2012 are detailed in the context of the machine development programs and hardware construction activities.
 Speaker: Brennan Goddard (CERN) Material:
• 18:30 Necessary LIU studies in the injectors during 2012 20'
A significant fraction of the Machine Development (MD) time in the LHC injectors in 2011 was devoted to the study of the intensity limitations in the injectors (e.g. space charge effects in PS and SPS, electron cloud effects in the PS and SPS, single bunch and multi-bunch instabilities in PS and SPS, emittance preservation across the injector chain, etc.). The main results achieved in 2011 will be presented as well as the questions that still remain unresolved and are of relevance for the LIU project. 2012 MDs will also continue exploring the potential of scenarios that might become operational in the future, like the development of a low gamma transition optics in the SPS or alternative production schemes for the LHC beams in the PS.
A tentative prioritized list of studies and their requirements in terms of machine time, resources and instrumentations will be provided.
 Speaker: Giovanni Rumolo (CERN) Material:
• 19:00 SPS: scrubbing or coating?- 20'
The operation of the SPS with high intensity bunched beams is limited by the electron cloud building-up in both the arcs and long straight sections. Two consolidation options have been considered: mitigation of the electron cloud using coatings or relying, as before, on the scrubbing runs. A status report on both options will be given with a particular emphasis on measurements plans for 2012 and pending issues. The testing needs, corresponding beam parameters and MD time in 2012 will be addressed. The criteria for the decision making and the corresponding schedule will be discussed.
 Speaker: Jose Miguel Jimenez (CERN) Material: Slides
• 19:30 Plans for ions in the injector complex 20'
The heavy ion beams required during the HL-LHC era will imply significant modifications to the existing injector chain. We review the various options, highlighting the importance of an early definition of the future needs and keeping in mind the compatibility with the rest of the future CERN physics programme.
 Speaker: Django Manglunki (CERN) Material:
• Friday, 10 February 2012
• 08:30 - 12:30 S09 -LHC related projects and studies – Part(II)  Conveners: Lucio Rossi (Chair), Riccardo De Maria (Scientific secretary) Material:
• 08:30 Beam current limit for HL-LHC 20'
The HL-LHC upgrades require beam currents, that are significantly increased beyond the original specifications of the LHC. The talk will explore expected limitations  in hardware systems (including  RF power, instrumentation, vacuum), the impact of  increased beam losses on quench statistics, risks due to beam current related damage, beam dynamics issues, loss-induced activation and single event upsets
 Speaker: Ralph Wolfgang Assmann (CERN) Material:
• 08:55 Do we really need an upgrade of the collimation system for HL-LHC? 20'
Several improvements are foreseen for the collimation  system  during  the LS1.  The talk will discuss  how the new performance level compares with the HL-LHC needs and if  further improvements will be needed to be compatible with the high luminosity operations  expected for the HL-LHC upgrade .

 Speaker: Stefano Redaelli (CERN) Material:
• 09:20 New Magnets for the IR: how far are we from HL-LHC target? 20'
The HL-LHC will benefit from new magnet technology (large aperture, Nb3Sn conductors) already under advanced R&D programs. The talk will review the status and roadmap of the new magnets for the high luminosity interaction regions.

 Speaker: Gianluca Sabbi (LBNL) Material:
• 09:45 Crab Cavities: from virtual reality to real reality? 20'
The talk will review the status and roadmap for the crab-cavity system that is foreseen for the HL-LHC upgrade project for luminosity enhancement and leveling.

 Speaker: Rama Calaga (CERN) Material:
• 10:10 coffee break 30'
• 10:40 LHeC and HE-LHC: Accelerator lay-out and challenges 20'
This talk will present a concise description of the layout of the two machines, together with the main accelerator-physics and technology challenges, detail the required LHC modifications, and describe the global schedules with decision points.

 Speaker: Frank Zimmermann (CERN) Material: Slides
• 11:05 Magnet R&D for LHeC and HE-LHC: synergy and competion? 20'
The new projects heavily rely on new magnet systems. The talk with illustrate the magnet R&D program for the LHeC (accelerator, transfer lines, kickers, interaction regions) and the HE-LHC (main Ring, SPS+, transfer lines, kickers). In particular synergies or parallel roadmaps will be highlighted together with the first steps foreseen for 2012.

 Speaker: Luca Bottura (CERN) Material:
• 11:30 SC Cavities R&D for LHeC an HE-LHC 20'
The new machines HE-LHC and LheC (whether or not linac-ring and ring-ring options will be favored) rely on new RF systems. The talk will analyze the synergies or competitions between the R&D strategies. The first steps foreseen for 2012 will be highlighted.

 Speaker: Erk Jensen (CERN) Material:
• 12:30 - 14:00 Lunch@Les Aiglons
• 14:00 - 16:00 S10 - Summary session  Conveners: Steve Myers (Chair), Frank Zimmermann (Scientific Secretary) Material: