[en] This paper summarizes the sessions devoted to Long Shutdown 1 (LS1) in the LHC, injectors and experiments. The time frame and start date were discussed, with the main activities from powering tests prior to warm-up up to physics were presented. The session finished with a discussion on the maximum reasonable energy. (author)

[en] A review and possible road map for future collider projects at the high energy frontier are presented. Opportunities for photon physics will be pointed out

No abstract available

[en] The summary session of the LHC Performance Workshop in Chamonix, 6-10 February 2012, synthesized one week of presentations and intense discussions on the near-, medium- and long-term strategy for the LHC and LHC upgrades. In particular, Chamonix’12 discussed the lessons from 2011, the strategy, beam energy and beam parameters for 2012, the planning for the Long Shutdown no. 1 (LS1), the measures and schemes for improving or maintaining the machine availability at higher beam energy, the injector performance and injector upgrade schedule, the HL-LHC project as well as possible additional or future LHC upgrades like LHeC and HELHC. Key workshop themes included the risk associated with 4 TeV beam energy in 2012, the beam energy after LS1, the turnaround time, the physics goal and optimized running schedule for 2012, the achievements and plans for Pb-Pb and p-Pb collisions, beam-beam effects, electron-cloud phenomena and UFOs. We report the proposals for decisions which have emerged at the Chamonix’12 workshop. (author)

[en] Collimator settings and available aperture are key parameters for deciding the reach in intensity and β*. In order to conclude on possible limits for the 2012 run, a summary is first given of the relevant running experience in 2011 and the collimation-related MDs. These include among others tight collimator settings, a quench test, and aperture measurements. Based on the 2011 experience, we conclude on possible running scenarios for 2012 in terms of collimator settings, intensity and β* from the collimation point of view

[en] Review of 2011 LHC Run from The Experiments Perspective, M. Ferro-Luzzi (PH-LBD): M. Ferro-Luzzi highlighted the excellent performance of the machine and the experiments in 2011 and the fast and impressive achievements both when operating with protons and Pb ions. In a month the same luminosity as during the full 2010 proton run was delivered, and a factor 16 higher luminosity was produced with Pb ions. The excellent machine performance allowed ATLAS and CMS to make interesting observations in the context of the Higgs’ boson search and LHCb found some evidence of CP violation in time-integrated D0 which could open the way for a new physics. Input from Evian, M. Lamont (BE-OP): M. Lamont presented a summary of what discussed in Evian about lessons learnt during 2011 operation and improvements foreseen for 2012. He underlined that 2011 was a remarkable year with a continuously faster increase in luminosity production and without real show stoppers. The machinewas characterized by operational robustness, a good reproducibility, stability, beam lifetime, optics control and an excellent performance of the Machine Protection system (MPs) and of the injectors. The 2011 Run: Availability Analysis, A. Macpherson (BE-OP): A. Macpherson spoke about machine availability in 2011 and gave some statistics of fills for p-p and Pb-Pb runs. He calculated a machine availability of 76.7% and that 33% of the operation time was spent in stable beam. The Hubner factor, which gives an estimate of the luminosity production duration, was slightly bigger than the expected 0.2 value both for the proton (0.22) and lead ion (0.24) runs. Stable beams lasted in average ∼6 hours but about 50% of the fills were shorter than 4 hours. Injection and Lessons for 2012, C. Bracco (TE-ABT): C. Bracco made a presentation on the performance of the injection system. The injection of 144 bunches became fully operational in 2011 in agreement with what predicted during the last Chamonix workshop. Moreover 288 bunches could be injected, during MD time, for both beams with a good margin between the losses and the BLM dump thresholds. Improvements are still needed to optimize the 25 ns beam in the injector chain and accumulate it in the LHC with a good lifetime; the results are encouraging in view of operation with the designed intensity. Machine Protection, M. Zerlauth (TE-MPE): M. Zerlauth introduced the architecture of the LHC Machine Protection System (MPS). He explained that this is a complex system that checks more than 10000 interlock conditions and has to evolve to follow operational changes, special runs and MD requirements. Vacuum Performance and Lessons for 2012, V. Baglin (TE-VSC): V. Baglin presented a talk on the main vacuum observations made in 2011: dynamic effects induced by the circulating beam (synchrotron radiation and e-clouds) and unexpected local pressure spikes. He explained that the desorption yield in the cold-warm transitions was much worse (factor 50) than in the warm-warm transition due to gas load from the cold part. Emittance Preservation, V. Kain (BE-OP): V. Kain spoke about emittance preservation all along the injectors chain up to collisions in the LHC. She explained that injectors behaved extremely well in 2011 and, for the 50 ns beams and a bunch population higher than nominal, an emittance blowup of 0.4 μm was measured from the PS to the SPS (from design report: 0.5 μm were estimated for 25 ns beams). On the other hand a 20-30% emittance growth is observed between the SPS flattop and LHC collisions. Several methods are used for emittance measurements (wire scanner, BSRT and luminosity) and all methods present some limitations. Moreover measurements in the SPS and in the LHC are not synchronized and refer to different beams.

[en] The session was devoted to address some aspects of the HL-LHC project and explore ideas on new machines for the long term future. (author)

[en] The session goal was to review the LHC upgrade plans related to the ion operation and to discuss the related machine updates for LHC RunII and RunIII and during the HL-LHC operation period

[en] The Welding Institute has participated to the realization of the Large Hadron Collider (LHC) in the framework of two expert missions, the first one in research and development and the other one in inspection. (O.M.)

[en] After LS1 the energy will be about 6.5 TeV. The physics potential of LHC is determined by the integrated luminosity useful for the experiments and not only by the peak luminosity. The integrated luminosity is determined by the peak luminosity, the luminosity decay and the efficiency of operation (availability). In this session two of these parameters are addressed, the peak luminosity and the availability. Presentations related to peak luminosity: • Performance potential of the injectors after LS1, Heiko Damerau; • Performance reach of LHC after LS1, Werner Herr. Presentations related to availability: • Magnet powering with zero downtime - a dream? Markus Zerlauth; • Beam systems without failures – what can be done? Matteo Solfaroli and Jan Uythoven; • Will we still see SEEs? Marco Calviani; • UFOs – will they take over? Tobias Baer; • Quenches: will there be any? Arjan Verweij