IPAC2019 - List of Authors (Redaelli, S.)

Paper	Title	Page
MOPMP031	Operation and Performance of the Cern Large Hadron Collider During Proton Run 2	504
	R. Steerenberg, M. Albert, R. Alemany-Fernández, T. Argyropoulos, E. Bravin, G.E. Crockford, J.-C. Dumont, K. Fuchsberger, R. Giachino, M. Giovannozzi, G.H. Hemelsoet, W. Höfle, D. Jacquet, M. Lamont, E. Métral, D. Nisbet, G. Papotti, M. Pojer, L. Ponce, S. Redaelli, B. Salvachua, M. Schaumann, M. Solfaroli, R. Suykerbuyk, G. Trad, J.A. Uythoven, S. Uznanski, D.J. Walsh, J. Wenninger, M. Zerlauth CERN, Geneva, Switzerland
	Run 2 of the CERN Large Hadron Collider (LHC) was successfully completed on 10th December 2018, achieving largely all goals set in terms of luminosity production. Following the first two-year long shutdown and the re-commissioning in 2015 at 6.5 TeV, the beam performance was increased to reach a peak luminosity of more than twice the design value and a colliding beam time ratio of 50%. This was accomplished thanks to the increased beam brightness from the injector chain, the high machine availability and the performance enhancements made in the LHC for which some methods and tools, foreseen for the High Luminosity LHC (HL-LHC) were tested and deployed operationally. This contribution provides an overview of the operational aspects, main limitations and achievements for the proton Run 2.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP031
About •	paper received ※ 13 May 2019 paper accepted ※ 17 May 2019 issue date ※ 21 June 2019
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MOPMP037	Updated High-Energy LHC Design	524
	F. Zimmermann, D. Amorim, S.A. Antipov, S. Arsenyev, M. Benedikt, R. Bruce, M.P. Crouch, S.D. Fartoukh, M. Giovannozzi, B. Goddard, M. Hofer, J. Keintzel, R. Kersevan, V. Mertens, J. Molson, Y. Muttoni, J.A. Osborne, V. Parma, V. Raginel, S. Redaelli, T. Risselada, I. Ruehl, B. Salvant, D. Schoerling, E.N. Shaposhnikova, L.J. Tavian, E. Todesco, R. Tomás, D. Tommasini, F. Valchkova-Georgieva, V. Venturi, D. Wollmann CERN, Geneva, Switzerland J.L. Abelleira, A. Abramov, E. Cruz Alaniz, H. Pikhartova, A. Seryi, L. van Riesen-Haupt JAI, Oxford, United Kingdom A. Apyan ANSL, Yerevan, Armenia J. Barranco García, L. Mether, T. Pieloni, L. Rivkin, C. Tambasco EPFL, Lausanne, Switzerland F. Burkart DESY, Hamburg, Germany Y. Cai, Y.M. Nosochkov SLAC, Menlo Park, California, USA G. Guillermo Cantón CINVESTAV, Mérida, Mexico K. Ohmi, K. Oide, D. Zhou KEK, Ibaraki, Japan
	Funding: This work was supported in part by the European Commission under the HORIZON 2020 project ARIES no.730871, and by the Swiss Accelerator Research and Technology collaboration CHART. We present updated design parameters for a future High-Energy LHC. A more realistic turnaround time has led to a revision of the target peak luminosity, as well as a choice of a larger IP beta function, and longer physics fills. Pushed parameters of the Nb₃Sn superconducting cable together with a modified layout of the 16 T dipole magnets resulted in revised field errors, updated dynamic-aperture simulations, and an associated re-evaluation of injector options. Collimators in the dispersion suppressors help achieve satisfactory cleaning performance. Longitudinal beam parameters ensure beam stability throughout the cycle. Intrabeam scattering rates and Touschek lifetime appear benign.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP037
About •	paper received ※ 10 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPRB048	Collimation System Studies for the FCC-hh	669
	R. Bruce, A. Abramov, A. Bertarelli, M.I. Besana, F. Carra, F. Cerutti, M. Fiascaris, G. Gobbi, A.M. Krainer, A. Lechner, A. Mereghetti, D. Mirarchi, J. Molson, M. Pasquali, S. Redaelli, D. Schulte, E. Skordis, M. Varasteh Anvar CERN, Meyrin, Switzerland A. Abramov JAI, Egham, Surrey, United Kingdom A. Faus-Golfe LAL, Orsay, France M. Serluca IN2P3-LAPP, Annecy-le-Vieux, France
	The Future Circular Collider (FCC-hh) is being designed as a 100 km ring that should collide 50 TeV proton beams. At 8.3 GJ, its stored beam energy will be a factor 28 higher than what has been achieved in the Large Hadron Collider, which has the highest stored beam energy among the colliders built so far. This puts unprecedented demands on the control of beam losses and collimation, since even a tiny beam loss risks quenching superconducting magnets. We present in this article the design of the FCC-hh collimation system and study the beam cleaning through simulations of tracking, energy deposition, and thermo-mechanical response. We investigate the collimation performance for design beam loss scenarios and potential bottlenecks are highlighted.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB048
About •	paper received ※ 18 April 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPRB049	Study of Beam-Gas Interactions at the LHC for the Physics Beyond Colliders Fixed-Target Study	673
	C. Boscolo Meneguolo, R. Bruce, F. Cerutti, M. Ferro-Luzzi, M. Giovannozzi, A. Mereghetti, J. Molson, S. Redaelli CERN, Geneva, Switzerland A. Abramov JAI, Egham, Surrey, United Kingdom
	Among several working groups formed in the framework of Physics Beyond Colliders study, launched at CERN in September 2016, there is one investigating specific fixed-target experiment proposals. Of particular interest is the study of high-density unpolarized or polarized gas target to be installed in the LHCb detector, using storage cells to enhance the target density. This work studies the impact of the interactions of 7 TeV proton beams with such gas targets on the LHC machine in terms of particle losses.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB049
About •	paper received ※ 17 April 2019 paper accepted ※ 19 May 2019 issue date ※ 21 June 2019
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MOPRB050	Performance of the Collimation System During the 2018 Lead Ion Run at the Large Hadron Collider	677
	N. Fuster-Martínez, R. Bruce, J.M. Jowett, A. Mereghetti, D. Mirarchi, S. Redaelli CERN, Geneva, Switzerland
	As part of the Large Hadron Collider (LHC) heavy-ion research programme, the last month of the 2018 LHC run was dedicated to Pb ion physics. Several heavy-ion runs have been performed since the start-up of the LHC. These runs are challenging for collimation, despite lower intensities, because of the degraded cleaning observed compared to protons. This is due to the differences of the interaction mechanisms in the collimators. Ions experience fragmentation and electromagnetic dissociation that result in a substantial flux of off-rigidity particles that escape the collimation system. In this paper, the collimation system performance and the experience gained during the 2018 Pb ion run are presented. The measured performance is compared with the expectation from the Sixtrack-FLUKA coupling simulations and the agreement discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB050
About •	paper received ※ 07 May 2019 paper accepted ※ 19 May 2019 issue date ※ 21 June 2019
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MOPRB051	Collimation System Upgrades for the High Luminosity Large Hadron Collider and Expected Cleaning Performance in Run 3	681
	A. Mereghetti, R. Bruce, N. Fuster-Martínez, D. Mirarchi, S. Redaelli CERN, Geneva, Switzerland
	In the framework of the High-Luminosity Large Hadron Collider project (HL-LHC), the LHC collimation system needs important upgrades to cope with the foreseen brighter beams. New collimation hardware will be installed in two phases, the first one during the LHC second Long Shutdown (LS2), in 2019-20, followed by a second phase starting in 2024 (LS3). This paper reviews the collimation upgrade plans for LS2, focused on a first impedance reduction of the system, through the installation of collimators based on new materials, and the improvement of collimation cleaning, achieved by adding new collimators in the cold dispersion suppressor regions. The performance of the new system in terms of cleaning inefficiency for proton and lead ion beams is presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB051
About •	paper received ※ 06 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPRB058	Collimation of Partially Stripped Ion Beams in the LHC	700
	A. Abramov, L.J. Nevay JAI, Egham, Surrey, United Kingdom R. Bruce, N. Fuster-Martínez, A.A. Gorzawski, M.W. Krasny, J. Molson, S. Redaelli, M. Schaumann CERN, Meyrin, Switzerland
	In the scope of the Physics Beyond Colliders studies, the Gamma Factory initiative proposes the use of partially stripped ions as a driver of a new type, high intensity photon source in CERN’s Large Hadron Collider (LHC). In 2018, the LHC accelerated and stored partially stripped 208-Pb-81+ ions for the first time. The collimation system efficiency recorded during this test was found to be prohibitively low. The worst losses were localised in the dispersion suppressor (DS) of the betatron-cleaning insertion. Analytic arguments and simulations show that the large losses are driven by the stripping of the remaining electron from the Pb nucleus by the primary collimators. The rising dispersion in the DS pushes the resulting off-rigidity, fully-stripped ions into the aperture of the superconducting magnets. In this study the measured loss maps are compared against results from simulations. Different mitigation strategies are outlined, including a dispersion suppressor (DS) collimator, crystal collimation or an orbit bump.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB058
About •	paper received ※ 10 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPRB059	Collimation of Heavy-Ion Beams in the HE-LHC	704
SUSPFO111	use link to see paper's listing under its alternate paper code
	A. Abramov, L.J. Nevay JAI, Egham, Surrey, United Kingdom R. Bruce, M.P. Crouch, N. Fuster-Martínez, A. Mereghetti, J. Molson, S. Redaelli CERN, Meyrin, Switzerland
	A design study for a future collider to be built in the LHC tunnel, the High-Energy Large Hadron Collider (HE-LHC), has been launched as part of the Future Circular Collider (FCC) study at CERN. It would provide proton collisions at a centre-of-mass energy of 27 TeV as well as collisions of heavy ions at the equivalent magnetic rigidity. HE-LHC is being designed under the stringent constraint of using the existing tunnel and therefore the resulting lattice and optics differ in layout and phase advance from the LHC. It is necessary to evaluate the performance of the collimation system for ion beams in HE-LHC in addition to proton beams. In the case of ion beams, the fragmentation and electromagnetic dissociation that relativistic heavy ions can undergo in collimators, as well as the unprecedented energy per nucleon of the HE-LHC, requires dedicated simulations. Results from a study of collimation efficiency for the nominal lead ion (Pb-82-208) beams performed with the SixTrack-FLUKA coupling framework are presented. These include loss maps with comparison against an estimated quench limit as well as detailed considerations of loss spikes in the superconducting aperture for critical sections of the machine such as the dispersion suppressors.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB059
About •	paper received ※ 18 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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MOPTS091	Mechanical Robustness of HL-LHC Collimator Designs	1070
	F. Carra, A. Bertarelli, G. Gobbi, J. Guardia, M. Guinchard, F.J. Harden, M. Pasquali, S. Redaelli, E. Skordis CERN, Meyrin, Switzerland
	Funding: This work has received funding from the European Union’s Horizon 2020 Research and Innovation programme under Grant Agreement No. 730871. Research supported by the HL-LHC project. Two new absorbing materials were developed as collimator inserts to fulfil the requirements of HL-LHC higher brightness beams: molybdenum-carbide graphite (MoGr) and copper-diamond (CuCD). These materials were tested under intense beam impacts at CERN HiRadMat facility in 2015, when full jaw prototypes were irradiated. Additional tests in HiRadMat were performed in 2017 on another series of material samples, including also improved grades of MoGr and CuCD, and different coating solutions. This paper summarizes the main results of the two experiments, with a main focus on the behaviour of the novel composite blocks, the metallic housing, as well as the cooling circuit. The experimental campaign confirmed the final choice for the materials and the design solutions for HL-LHC collimators, and constituted a unique chance of benchmarking numerical models. In particular, the tests validated the selection of MoGr for primary and secondary collimators, and CuCD as a valid solution for robust tertiary collimators.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS091
About •	paper received ※ 12 April 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPTS093	Ultra-High Vacuum Characterization of Molybdenum-Carbide Graphite for HL-LHC Collimators	1078
	F. Carra, C. Accettura, A. Bertarelli, G. Bregliozzi, G. Cattenoz, S. Redaelli, M. Taborelli CERN, Meyrin, Switzerland M. Beghi POLIMI, Milano, Italy J. Guardia Valenzuela Universidad de Zaragoza, Zaragoza, Spain
	Funding: This work has received funding from the European Union’s Horizon 2020 Research and Innovation programme under Grant Agreement No. 730871. Research supported by the HL-LHC project In view of the High-Luminosity upgrade of the Large Hadron Collider (LHC) collimation system, a family of novel molybdenum-carbide graphite (MoGr) composites was developed to meet the challenging requirements of HL-LHC beam-halo collimation, in particular the electrical conductivity and thermo-mechanical performances. The Ultra-High Vacuum (UHV) behaviour of this material was extensively characterized to assess its compatibility with the accelerator’s specifications. The results presented in this paper correlate the outgassing behaviour with the microscopic features of MoGr compared to other graphite-based materials. Residual gas analysis (RGA) was exploited to optimize post-production treatments.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS093
About •	paper received ※ 12 April 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019
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TUZZPLM1	Operational Results of LHC Collimator Alignment Using Machine Learning	1208
SUSPFO053	use link to see paper's listing under its alternate paper code
	G. Azzopardi, A. Muscat, G. Valentino University of Malta, Information and Communication Technology, Msida, Malta S. Redaelli, B. Salvachua CERN, Geneva, Switzerland
	A complex collimation system is installed in the Large Hadron Collider to protect sensitive equipment from unavoidable beam losses. The collimators are positioned close to the beam in the form of a hierarchy, which is guaranteed by precisely aligning each collimator with a precision of a few tens of micrometers. During past years, collimator alignments were performed semi-automatically, such that collimation experts had to be present to oversee and control the alignment. In 2018, machine learning was introduced to develop a new fully-automatic alignment tool, which was used for collimator alignments throughout the year. This paper discusses how machine learning was used to automate the alignment, whilst focusing on the operational results obtained when testing the new software in the LHC. Automatically aligning the collimators decreased the alignment time at injection by a factor of three whilst maintaining the accuracy of the results. G.Valentino et al., "Semi-automatic beam-based LHC collimator alignment", PRSTAB, no.5, 2012.
	Slides TUZZPLM1 [6.060 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUZZPLM1
About •	paper received ※ 10 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019
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WEYYPLM2	The 2018 Heavy-Ion Run of the LHC	2258
	J.M. Jowett, C. Bahamonde Castro, W. Bartmann, C. Bracco, R. Bruce, J.M. Coello de Portugal, J. Dilly, S.D. Fartoukh, E. Fol, N. Fuster-Martínez, A. Garcia-Tabares, M. Hofer, E.B. Holzer, M.A. Jebramcik, J. Keintzel, A. Lechner, E.H. Maclean, L. Malina, T. Medvedeva, A. Mereghetti, T.H.B. Persson, B.Aa. Petersen, S. Redaelli, B. Salvachua, M. Schaumann, C. Schwick, M. Solfaroli, M.L. Spitznagel, H. Timko, R. Tomás, A. Wegscheider, J. Wenninger, D. Wollmann CERN, Meyrin, Switzerland D. Mirarchi The University of Manchester, The Photon Science Institute, Manchester, United Kingdom
	The fourth one-month Pb-Pb collision run brought LHC Run 2 to an end in December 2018. Following the tendency to reduce dependence on the configuration of the preceding proton run, a completely new optics cycle with the strongest ever focussing at the ALICE and LHCb experiments was designed and rapidly implemented, demonstrating the maturity of the collider’s operating modes. Beam-loss monitor thresholds were carefully adjusted to provide optimal protection from the multiple loss mechanisms in heavy-ion operation. A switch from a basic bunch-spacing of 100 ns to 75 ns was made as the beam became available from the injector chain. A new record luminosity, 6 times the original design and close to the operating value proposed for HL-LHC, provided validation of the strategy for mitigating quenches due to bound-free pair production (BFPP) at the interaction points of the ATLAS and CMS experiments. Most of the beam parameters of the HL-LHC Pb-Pb upgrade were attained during this run and the integrated luminosity goals for the first 10 years of LHC operation were substantially exceeded.
	Slides WEYYPLM2 [10.884 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEYYPLM2
About •	paper received ※ 08 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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WEYYPLM3	First Results of the Compensation of the Beam-Beam Effect with DC Wires in the LHC	2262
	G. Sterbini, D. Amorim, H. Bartosik, A. Bertarelli, R. Bruce, X. Buffat, F. Carra, L.R. Carver, G. Cattenoz, E. Effinger, S.D. Fartoukh, N. Fuster-Martínez, M. Gąsior, M. Gonzalez-Berges, A.A. Gorzawski, G.H. Hemelsoet, M. Hostettler, G. Iadarola, O.R. Jones, N. Karastathis, S. Kostoglou, I. Lamas Garcia, T.E. Levens, L.E. Medina Medrano, D. Mirarchi, J. Olexa, S. Papadopoulou, Y. Papaphilippou, D. Pellegrini, M. Pojer, L. Ponce, A. Poyet, S. Redaelli, A. Rossi, B. Salvachua, H. Schmickler, F. Schmidt, K. Skoufaris, M. Solfaroli, R. Tomás, G. Trad, D. Valuch, C. Xu, C. Zamantzas, P. Zisopoulos CERN, Geneva, Switzerland D. Amorim Grenoble-INP Phelma, Grenoble, France M. Fitterer, A. Valishev Fermilab, Batavia, Illinois, USA D. Kaltchev TRIUMF, Vancouver, Canada S. Kostoglou National Technical University of Athens, Zografou, Greece A.E. Levichev BINP SB RAS, Novosibirsk, Russia A. Poyet Université Grenoble Alpes, Grenoble, France
	The compensation of the long-range beam-beam interactions using DC wires is presently under study as an option for enhancing the machine performance in the frame of the High-Luminosity LHC project (HL-LHC). The original idea dates back more than 15 years. After the installation of four wire prototypes in the LHC in 2018, a successful experimental campaign was performed during the last months. The experimental setup and the main results are reported in this paper.
	Slides WEYYPLM3 [6.371 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEYYPLM3
About •	paper received ※ 06 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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WEPMP031	SPS Slow Extraction Losses and Activation: Update on Recent Improvements	2391
	M.A. Fraser, B. Balhan, H. Bartosik, J. Bernhard, C. Bertone, D. Björkman, J.C.C.M. Borburgh, M. Brugger, N. Charitonidis, N. Conan, K. Cornelis, Y. Dutheil, L.S. Esposito, R. Garcia Alia, L. Gatignon, C.M. Genton, B. Goddard, C. Heßler, Y. Kadi, V. Kain, A. Mereghetti, M. Pari, M. Patecki, J. Prieto, S. Redaelli, F. Roncarolo, R. Rossi, W. Scandale, N. Solieri, J. Spanggaard, O. Stein, L.S. Stoel, F.M. Velotti, H. Vincke CERN, Meyrin, Switzerland D. Barna, K. Brunner Wigner Research Centre for Physics, Institute for Particle and Nuclear Physics, Budapest, Hungary
	Annual high intensity requests of over 10¹⁹ protons on target (POT) from the CERN Super Proton Synchrotron (SPS) Fixed Target (FT) physics program continue, with the prospect of requests for even higher, unprecedented levels in the coming decade. A concerted and multifaceted R&D effort has been launched to understand and reduce the slow extraction induced radioactivation of the SPS and to anticipate future experimental proposals, such as SHiP* at the SPS Beam Dump Facility (BDF)*, which will request an additional 4·10¹⁹ POT per year. In this contribution, we report on operational improvements and recent advances that have been made to significantly reduce the slow extraction losses, by up to a factor of 3, with the deployment of new extraction concepts, including passive and active (thin, bent crystal) diffusers and extraction on the third-integer resonance with octupoles. In light of the successful tests of the prototype extraction loss reduction schemes, an outlook and implications for future SPS FT operation will be presented. A. Golutvin et al., Rep. CERN-SPSC-2015-016 (SPSC-P-350), CERN, Geneva, Switzerland, Apr. 2015. ** M. Lamont et al., Rep. CERN-PBC-REPORT-2018-001, CERN, Geneva, Switzerland, 11 Dec 2018.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPMP031
About •	paper received ※ 14 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019
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THXXPLM2	Demonstration of Loss Reduction Using a Thin Bent Crystal to Shadow an Electrostatic Septum During Resonant Slow Extraction	3399
	F.M. Velotti, P. Bestmann, M.E.J. Butcher, M. Calviani, M. Di Castro, M. Donzé, L.S. Esposito, M.A. Fraser, M. Garattini, S.S. Gilardoni, B. Goddard, V. Kain, J. Lendaro, A. Masi, D. Mirarchi, M. Pari, J. Prieto, S. Redaelli, R. Rossi, W. Scandale, R. Seidenbinder, P. Serrano Galvez, L.S. Stoel, C. Zamantzas, V. Zhovkovska CERN, Meyrin, Switzerland F.M. Addesa, F. Iacoangeli INFN-Roma, Roma, Italy A.G. Afonin, Y.A. Chesnokov, A.A. Durum, V.A. Maisheev, Yu.E. Sandomirskiy, A.A. Yanovich IHEP, Moscow Region, Russia J.E. Borg, M. Garattini, G. Hall, T. James, M. Pesaresi Imperial College of Science and Technology, Department of Physics, London, United Kingdom A.S. Denisov, Y. Gavrikov, Yu.M. Ivanov, M.A. Koznov, L.G. Malyarenko, V. Skorobogatov PNPI, Gatchina, Leningrad District, Russia F. Galluccio INFN-Napoli, Napoli, Italy F. Murtas INFN/LNF, Frascati, Italy
	A proof-of-principle experiment demonstrating the feasibility of using a thin, bent crystal aligned upstream of an extraction septum (ES) to increase the efficiency of the third-integer resonant slow extraction process has been carried out at the CERN Super Proton Synchrotron (SPS). With the primary aim of reducing the beam loss and induced radio-activation of the SPS, the crystal was aligned to both the beam and the septum to reduce by up to 40% the beam intensity impinging the ES and increase the intensity entering the external transfer line. In this contribution, we introduce the concept and the prototype system that was installed in 2018 before reporting in detail on the dedicated program of machine development studies carried out to characterise its performance and demonstrate operational feasibility. The performance reach and compatibility with other loss reduction techniques proposed to further increase the extraction efficiency, such as phase space folding with octupoles, is discussed in view of future high intensity operation.
	Slides THXXPLM2 [1.397 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THXXPLM2
About •	paper received ※ 15 May 2019 paper accepted ※ 28 May 2019 issue date ※ 21 June 2019
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THPGW057	HL-LHC Full Remote Alignment Study	3716
	A. Herty, R. De Maria, P. Fessia, D. Gamba, M. Giovannozzi, J. Hansen, I. Lamas Garcia, H. Mainaud Durand, S. Redaelli CERN, Meyrin, Switzerland
	Funding: Research supported by the HL-LHC project. This study explores the benefits of extending the monitoring and remote alignment concept, proposed in the HL-LHC baseline, to additional components of the matching sections of the HL-LHC. The objective was to evaluate the benefits in terms of equipment performance and new opportunities for system simplification. In collaboration with the HL-LHC Working Group on Alignment, critical input parameters such as ground motion, manufacturing, assembly, and alignment tolerances, have been quantified. Solutions for the selected, manually aligned compo-nents have been investigated with the particular focus on vacuum design, mechanical design and the new alignment concept compatible with reliability and maintainability requirements. In this context, collimators and masks are key elements to be included in the extended alignment system. Their supporting systems will integrate the concept of on-line monitoring sensors and an actuator based, remote alignment platform. The full remote alignment of components will provide a positive impact to the machine operation reducing the need of human intervention in the tunnel and providing enhanced flexibility to perform the required alignment adjustment as part of an operational tool for the HL-LHC.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW057
About •	paper received ※ 09 May 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019
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THPRB031	Operational Performance of the Machine Protection Systems of the Large Hadron Collider During Run 2 and Lessons Learnt for the LIU/HL-LHC Era	3875
	M. Zerlauth, A. Antoine, W. Bartmann, C. Bracco, E. Carlier, Z. Charifoulline, R. Denz, B. Goddard, A. Lechner, N. Magnin, C. Martin, R. Mompo, S. Redaelli, I. Romera, B. Salvachua, R. Schmidt, J.A. Uythoven, A.P. Verweij, J. Wenninger, C. Wiesner, D. Wollmann, C. Zamantzas CERN, Geneva, Switzerland
	The Large Hadron Collider (LHC) has successfully completed its second operational run of four years length in December 2018. Operation will be stopped during two years for maintenance and upgrades. To allow for the successful completion of the diverse physics program at 6.5 TeV, the LHC has been routinely operating with stored beam energies close to 300 MJ per beam during high intensity proton runs as well as being frequently reconfigured to allow for special physic runs and important machine developments. No significant damage has incurred to the protected accelerator equipment throughout the run thanks to the excellent performance of the various machine protection systems, however a number of important observations and new failure scenarios have been identified, which were studied experimentally as well as through detailed simulations. In this contribution, we provide an overview of the performance of the machine protection systems throughout Run 2 as well as the important lessons learnt that will impact consolidation actions and the upgrade of the machine protection systems for the LIU/HL-LHC era.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB031
About •	paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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Paper

Title

Page

Operation and Performance of the Cern Large Hadron Collider During Proton Run 2

504

R. Steerenberg, M. Albert, R. Alemany-Fernández, T. Argyropoulos, E. Bravin, G.E. Crockford, J.-C. Dumont, K. Fuchsberger, R. Giachino, M. Giovannozzi, G.H. Hemelsoet, W. Höfle, D. Jacquet, M. Lamont, E. Métral, D. Nisbet, G. Papotti, M. Pojer, L. Ponce, S. Redaelli, B. Salvachua, M. Schaumann, M. Solfaroli, R. Suykerbuyk, G. Trad, J.A. Uythoven, S. Uznanski, D.J. Walsh, J. Wenninger, M. Zerlauth
CERN, Geneva, Switzerland

Run 2 of the CERN Large Hadron Collider (LHC) was successfully completed on 10th December 2018, achieving largely all goals set in terms of luminosity production. Following the first two-year long shutdown and the re-commissioning in 2015 at 6.5 TeV, the beam performance was increased to reach a peak luminosity of more than twice the design value and a colliding beam time ratio of 50%. This was accomplished thanks to the increased beam brightness from the injector chain, the high machine availability and the performance enhancements made in the LHC for which some methods and tools, foreseen for the High Luminosity LHC (HL-LHC) were tested and deployed operationally. This contribution provides an overview of the operational aspects, main limitations and achievements for the proton Run 2.

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paper received ※ 13 May 2019 paper accepted ※ 17 May 2019 issue date ※ 21 June 2019

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MOPMP037

Updated High-Energy LHC Design

524

F. Zimmermann, D. Amorim, S.A. Antipov, S. Arsenyev, M. Benedikt, R. Bruce, M.P. Crouch, S.D. Fartoukh, M. Giovannozzi, B. Goddard, M. Hofer, J. Keintzel, R. Kersevan, V. Mertens, J. Molson, Y. Muttoni, J.A. Osborne, V. Parma, V. Raginel, S. Redaelli, T. Risselada, I. Ruehl, B. Salvant, D. Schoerling, E.N. Shaposhnikova, L.J. Tavian, E. Todesco, R. Tomás, D. Tommasini, F. Valchkova-Georgieva, V. Venturi, D. Wollmann
CERN, Geneva, Switzerland
J.L. Abelleira, A. Abramov, E. Cruz Alaniz, H. Pikhartova, A. Seryi, L. van Riesen-Haupt
JAI, Oxford, United Kingdom
A. Apyan
ANSL, Yerevan, Armenia
J. Barranco García, L. Mether, T. Pieloni, L. Rivkin, C. Tambasco
EPFL, Lausanne, Switzerland
F. Burkart
DESY, Hamburg, Germany
Y. Cai, Y.M. Nosochkov
SLAC, Menlo Park, California, USA
G. Guillermo Cantón
CINVESTAV, Mérida, Mexico
K. Ohmi, K. Oide, D. Zhou
KEK, Ibaraki, Japan

Funding: This work was supported in part by the European Commission under the HORIZON 2020 project ARIES no.730871, and by the Swiss Accelerator Research and Technology collaboration CHART.
We present updated design parameters for a future High-Energy LHC. A more realistic turnaround time has led to a revision of the target peak luminosity, as well as a choice of a larger IP beta function, and longer physics fills. Pushed parameters of the Nb₃Sn superconducting cable together with a modified layout of the 16 T dipole magnets resulted in revised field errors, updated dynamic-aperture simulations, and an associated re-evaluation of injector options. Collimators in the dispersion suppressors help achieve satisfactory cleaning performance. Longitudinal beam parameters ensure beam stability throughout the cycle. Intrabeam scattering rates and Touschek lifetime appear benign.

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paper received ※ 10 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPRB048

Collimation System Studies for the FCC-hh

669

R. Bruce, A. Abramov, A. Bertarelli, M.I. Besana, F. Carra, F. Cerutti, M. Fiascaris, G. Gobbi, A.M. Krainer, A. Lechner, A. Mereghetti, D. Mirarchi, J. Molson, M. Pasquali, S. Redaelli, D. Schulte, E. Skordis, M. Varasteh Anvar
CERN, Meyrin, Switzerland
A. Abramov
JAI, Egham, Surrey, United Kingdom
A. Faus-Golfe
LAL, Orsay, France
M. Serluca
IN2P3-LAPP, Annecy-le-Vieux, France

The Future Circular Collider (FCC-hh) is being designed as a 100 km ring that should collide 50 TeV proton beams. At 8.3 GJ, its stored beam energy will be a factor 28 higher than what has been achieved in the Large Hadron Collider, which has the highest stored beam energy among the colliders built so far. This puts unprecedented demands on the control of beam losses and collimation, since even a tiny beam loss risks quenching superconducting magnets. We present in this article the design of the FCC-hh collimation system and study the beam cleaning through simulations of tracking, energy deposition, and thermo-mechanical response. We investigate the collimation performance for design beam loss scenarios and potential bottlenecks are highlighted.

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paper received ※ 18 April 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPRB049

Study of Beam-Gas Interactions at the LHC for the Physics Beyond Colliders Fixed-Target Study

673

C. Boscolo Meneguolo, R. Bruce, F. Cerutti, M. Ferro-Luzzi, M. Giovannozzi, A. Mereghetti, J. Molson, S. Redaelli
CERN, Geneva, Switzerland
A. Abramov
JAI, Egham, Surrey, United Kingdom

Among several working groups formed in the framework of Physics Beyond Colliders study, launched at CERN in September 2016, there is one investigating specific fixed-target experiment proposals. Of particular interest is the study of high-density unpolarized or polarized gas target to be installed in the LHCb detector, using storage cells to enhance the target density. This work studies the impact of the interactions of 7 TeV proton beams with such gas targets on the LHC machine in terms of particle losses.

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paper received ※ 17 April 2019 paper accepted ※ 19 May 2019 issue date ※ 21 June 2019

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MOPRB050

Performance of the Collimation System During the 2018 Lead Ion Run at the Large Hadron Collider

677

N. Fuster-Martínez, R. Bruce, J.M. Jowett, A. Mereghetti, D. Mirarchi, S. Redaelli
CERN, Geneva, Switzerland

As part of the Large Hadron Collider (LHC) heavy-ion research programme, the last month of the 2018 LHC run was dedicated to Pb ion physics. Several heavy-ion runs have been performed since the start-up of the LHC. These runs are challenging for collimation, despite lower intensities, because of the degraded cleaning observed compared to protons. This is due to the differences of the interaction mechanisms in the collimators. Ions experience fragmentation and electromagnetic dissociation that result in a substantial flux of off-rigidity particles that escape the collimation system. In this paper, the collimation system performance and the experience gained during the 2018 Pb ion run are presented. The measured performance is compared with the expectation from the Sixtrack-FLUKA coupling simulations and the agreement discussed.

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paper received ※ 07 May 2019 paper accepted ※ 19 May 2019 issue date ※ 21 June 2019

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MOPRB051

Collimation System Upgrades for the High Luminosity Large Hadron Collider and Expected Cleaning Performance in Run 3

681

A. Mereghetti, R. Bruce, N. Fuster-Martínez, D. Mirarchi, S. Redaelli
CERN, Geneva, Switzerland

In the framework of the High-Luminosity Large Hadron Collider project (HL-LHC), the LHC collimation system needs important upgrades to cope with the foreseen brighter beams. New collimation hardware will be installed in two phases, the first one during the LHC second Long Shutdown (LS2), in 2019-20, followed by a second phase starting in 2024 (LS3). This paper reviews the collimation upgrade plans for LS2, focused on a first impedance reduction of the system, through the installation of collimators based on new materials, and the improvement of collimation cleaning, achieved by adding new collimators in the cold dispersion suppressor regions. The performance of the new system in terms of cleaning inefficiency for proton and lead ion beams is presented.

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paper received ※ 06 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPRB058

Collimation of Partially Stripped Ion Beams in the LHC

700

A. Abramov, L.J. Nevay
JAI, Egham, Surrey, United Kingdom
R. Bruce, N. Fuster-Martínez, A.A. Gorzawski, M.W. Krasny, J. Molson, S. Redaelli, M. Schaumann
CERN, Meyrin, Switzerland

In the scope of the Physics Beyond Colliders studies, the Gamma Factory initiative proposes the use of partially stripped ions as a driver of a new type, high intensity photon source in CERN’s Large Hadron Collider (LHC). In 2018, the LHC accelerated and stored partially stripped 208-Pb-81+ ions for the first time. The collimation system efficiency recorded during this test was found to be prohibitively low. The worst losses were localised in the dispersion suppressor (DS) of the betatron-cleaning insertion. Analytic arguments and simulations show that the large losses are driven by the stripping of the remaining electron from the Pb nucleus by the primary collimators. The rising dispersion in the DS pushes the resulting off-rigidity, fully-stripped ions into the aperture of the superconducting magnets. In this study the measured loss maps are compared against results from simulations. Different mitigation strategies are outlined, including a dispersion suppressor (DS) collimator, crystal collimation or an orbit bump.

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paper received ※ 10 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPRB059

Collimation of Heavy-Ion Beams in the HE-LHC

704

SUSPFO111

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A. Abramov, L.J. Nevay
JAI, Egham, Surrey, United Kingdom
R. Bruce, M.P. Crouch, N. Fuster-Martínez, A. Mereghetti, J. Molson, S. Redaelli
CERN, Meyrin, Switzerland

A design study for a future collider to be built in the LHC tunnel, the High-Energy Large Hadron Collider (HE-LHC), has been launched as part of the Future Circular Collider (FCC) study at CERN. It would provide proton collisions at a centre-of-mass energy of 27 TeV as well as collisions of heavy ions at the equivalent magnetic rigidity. HE-LHC is being designed under the stringent constraint of using the existing tunnel and therefore the resulting lattice and optics differ in layout and phase advance from the LHC. It is necessary to evaluate the performance of the collimation system for ion beams in HE-LHC in addition to proton beams. In the case of ion beams, the fragmentation and electromagnetic dissociation that relativistic heavy ions can undergo in collimators, as well as the unprecedented energy per nucleon of the HE-LHC, requires dedicated simulations. Results from a study of collimation efficiency for the nominal lead ion (Pb-82-208) beams performed with the SixTrack-FLUKA coupling framework are presented. These include loss maps with comparison against an estimated quench limit as well as detailed considerations of loss spikes in the superconducting aperture for critical sections of the machine such as the dispersion suppressors.

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paper received ※ 18 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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MOPTS091

Mechanical Robustness of HL-LHC Collimator Designs

1070

F. Carra, A. Bertarelli, G. Gobbi, J. Guardia, M. Guinchard, F.J. Harden, M. Pasquali, S. Redaelli, E. Skordis
CERN, Meyrin, Switzerland

Funding: This work has received funding from the European Union’s Horizon 2020 Research and Innovation programme under Grant Agreement No. 730871. Research supported by the HL-LHC project.
Two new absorbing materials were developed as collimator inserts to fulfil the requirements of HL-LHC higher brightness beams: molybdenum-carbide graphite (MoGr) and copper-diamond (CuCD). These materials were tested under intense beam impacts at CERN HiRadMat facility in 2015, when full jaw prototypes were irradiated. Additional tests in HiRadMat were performed in 2017 on another series of material samples, including also improved grades of MoGr and CuCD, and different coating solutions. This paper summarizes the main results of the two experiments, with a main focus on the behaviour of the novel composite blocks, the metallic housing, as well as the cooling circuit. The experimental campaign confirmed the final choice for the materials and the design solutions for HL-LHC collimators, and constituted a unique chance of benchmarking numerical models. In particular, the tests validated the selection of MoGr for primary and secondary collimators, and CuCD as a valid solution for robust tertiary collimators.

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paper received ※ 12 April 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPTS093

Ultra-High Vacuum Characterization of Molybdenum-Carbide Graphite for HL-LHC Collimators

1078

F. Carra, C. Accettura, A. Bertarelli, G. Bregliozzi, G. Cattenoz, S. Redaelli, M. Taborelli
CERN, Meyrin, Switzerland
M. Beghi
POLIMI, Milano, Italy
J. Guardia Valenzuela
Universidad de Zaragoza, Zaragoza, Spain

Funding: This work has received funding from the European Union’s Horizon 2020 Research and Innovation programme under Grant Agreement No. 730871. Research supported by the HL-LHC project
In view of the High-Luminosity upgrade of the Large Hadron Collider (LHC) collimation system, a family of novel molybdenum-carbide graphite (MoGr) composites was developed to meet the challenging requirements of HL-LHC beam-halo collimation, in particular the electrical conductivity and thermo-mechanical performances. The Ultra-High Vacuum (UHV) behaviour of this material was extensively characterized to assess its compatibility with the accelerator’s specifications. The results presented in this paper correlate the outgassing behaviour with the microscopic features of MoGr compared to other graphite-based materials. Residual gas analysis (RGA) was exploited to optimize post-production treatments.

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paper received ※ 12 April 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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TUZZPLM1

Operational Results of LHC Collimator Alignment Using Machine Learning

1208

SUSPFO053

use link to see paper's listing under its alternate paper code

G. Azzopardi, A. Muscat, G. Valentino
University of Malta, Information and Communication Technology, Msida, Malta
S. Redaelli, B. Salvachua
CERN, Geneva, Switzerland

A complex collimation system is installed in the Large Hadron Collider to protect sensitive equipment from unavoidable beam losses. The collimators are positioned close to the beam in the form of a hierarchy, which is guaranteed by precisely aligning each collimator with a precision of a few tens of micrometers. During past years, collimator alignments were performed semi-automatically*, such that collimation experts had to be present to oversee and control the alignment. In 2018, machine learning was introduced to develop a new fully-automatic alignment tool, which was used for collimator alignments throughout the year. This paper discusses how machine learning was used to automate the alignment, whilst focusing on the operational results obtained when testing the new software in the LHC. Automatically aligning the collimators decreased the alignment time at injection by a factor of three whilst maintaining the accuracy of the results.
*G.Valentino et al., "Semi-automatic beam-based LHC collimator alignment", PRSTAB, no.5, 2012.

Slides TUZZPLM1 [6.060 MB]

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paper received ※ 10 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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WEYYPLM2

The 2018 Heavy-Ion Run of the LHC

2258

J.M. Jowett, C. Bahamonde Castro, W. Bartmann, C. Bracco, R. Bruce, J.M. Coello de Portugal, J. Dilly, S.D. Fartoukh, E. Fol, N. Fuster-Martínez, A. Garcia-Tabares, M. Hofer, E.B. Holzer, M.A. Jebramcik, J. Keintzel, A. Lechner, E.H. Maclean, L. Malina, T. Medvedeva, A. Mereghetti, T.H.B. Persson, B.Aa. Petersen, S. Redaelli, B. Salvachua, M. Schaumann, C. Schwick, M. Solfaroli, M.L. Spitznagel, H. Timko, R. Tomás, A. Wegscheider, J. Wenninger, D. Wollmann
CERN, Meyrin, Switzerland
D. Mirarchi
The University of Manchester, The Photon Science Institute, Manchester, United Kingdom

The fourth one-month Pb-Pb collision run brought LHC Run 2 to an end in December 2018. Following the tendency to reduce dependence on the configuration of the preceding proton run, a completely new optics cycle with the strongest ever focussing at the ALICE and LHCb experiments was designed and rapidly implemented, demonstrating the maturity of the collider’s operating modes. Beam-loss monitor thresholds were carefully adjusted to provide optimal protection from the multiple loss mechanisms in heavy-ion operation. A switch from a basic bunch-spacing of 100 ns to 75 ns was made as the beam became available from the injector chain. A new record luminosity, 6 times the original design and close to the operating value proposed for HL-LHC, provided validation of the strategy for mitigating quenches due to bound-free pair production (BFPP) at the interaction points of the ATLAS and CMS experiments. Most of the beam parameters of the HL-LHC Pb-Pb upgrade were attained during this run and the integrated luminosity goals for the first 10 years of LHC operation were substantially exceeded.

Slides WEYYPLM2 [10.884 MB]

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paper received ※ 08 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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WEYYPLM3

First Results of the Compensation of the Beam-Beam Effect with DC Wires in the LHC

2262

G. Sterbini, D. Amorim, H. Bartosik, A. Bertarelli, R. Bruce, X. Buffat, F. Carra, L.R. Carver, G. Cattenoz, E. Effinger, S.D. Fartoukh, N. Fuster-Martínez, M. Gąsior, M. Gonzalez-Berges, A.A. Gorzawski, G.H. Hemelsoet, M. Hostettler, G. Iadarola, O.R. Jones, N. Karastathis, S. Kostoglou, I. Lamas Garcia, T.E. Levens, L.E. Medina Medrano, D. Mirarchi, J. Olexa, S. Papadopoulou, Y. Papaphilippou, D. Pellegrini, M. Pojer, L. Ponce, A. Poyet, S. Redaelli, A. Rossi, B. Salvachua, H. Schmickler, F. Schmidt, K. Skoufaris, M. Solfaroli, R. Tomás, G. Trad, D. Valuch, C. Xu, C. Zamantzas, P. Zisopoulos
CERN, Geneva, Switzerland
D. Amorim
Grenoble-INP Phelma, Grenoble, France
M. Fitterer, A. Valishev
Fermilab, Batavia, Illinois, USA
D. Kaltchev
TRIUMF, Vancouver, Canada
S. Kostoglou
National Technical University of Athens, Zografou, Greece
A.E. Levichev
BINP SB RAS, Novosibirsk, Russia
A. Poyet
Université Grenoble Alpes, Grenoble, France

The compensation of the long-range beam-beam interactions using DC wires is presently under study as an option for enhancing the machine performance in the frame of the High-Luminosity LHC project (HL-LHC). The original idea dates back more than 15 years. After the installation of four wire prototypes in the LHC in 2018, a successful experimental campaign was performed during the last months. The experimental setup and the main results are reported in this paper.

Slides WEYYPLM3 [6.371 MB]

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paper received ※ 06 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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WEPMP031

SPS Slow Extraction Losses and Activation: Update on Recent Improvements

2391

M.A. Fraser, B. Balhan, H. Bartosik, J. Bernhard, C. Bertone, D. Björkman, J.C.C.M. Borburgh, M. Brugger, N. Charitonidis, N. Conan, K. Cornelis, Y. Dutheil, L.S. Esposito, R. Garcia Alia, L. Gatignon, C.M. Genton, B. Goddard, C. Heßler, Y. Kadi, V. Kain, A. Mereghetti, M. Pari, M. Patecki, J. Prieto, S. Redaelli, F. Roncarolo, R. Rossi, W. Scandale, N. Solieri, J. Spanggaard, O. Stein, L.S. Stoel, F.M. Velotti, H. Vincke
CERN, Meyrin, Switzerland
D. Barna, K. Brunner
Wigner Research Centre for Physics, Institute for Particle and Nuclear Physics, Budapest, Hungary

Annual high intensity requests of over 10¹⁹ protons on target (POT) from the CERN Super Proton Synchrotron (SPS) Fixed Target (FT) physics program continue, with the prospect of requests for even higher, unprecedented levels in the coming decade. A concerted and multifaceted R&D effort has been launched to understand and reduce the slow extraction induced radioactivation of the SPS and to anticipate future experimental proposals, such as SHiP* at the SPS Beam Dump Facility (BDF)**, which will request an additional 4·10¹⁹ POT per year. In this contribution, we report on operational improvements and recent advances that have been made to significantly reduce the slow extraction losses, by up to a factor of 3, with the deployment of new extraction concepts, including passive and active (thin, bent crystal) diffusers and extraction on the third-integer resonance with octupoles. In light of the successful tests of the prototype extraction loss reduction schemes, an outlook and implications for future SPS FT operation will be presented.
* A. Golutvin et al., Rep. CERN-SPSC-2015-016 (SPSC-P-350), CERN, Geneva, Switzerland, Apr. 2015.
** M. Lamont et al., Rep. CERN-PBC-REPORT-2018-001, CERN, Geneva, Switzerland, 11 Dec 2018.

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paper received ※ 14 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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THXXPLM2

Demonstration of Loss Reduction Using a Thin Bent Crystal to Shadow an Electrostatic Septum During Resonant Slow Extraction

3399

F.M. Velotti, P. Bestmann, M.E.J. Butcher, M. Calviani, M. Di Castro, M. Donzé, L.S. Esposito, M.A. Fraser, M. Garattini, S.S. Gilardoni, B. Goddard, V. Kain, J. Lendaro, A. Masi, D. Mirarchi, M. Pari, J. Prieto, S. Redaelli, R. Rossi, W. Scandale, R. Seidenbinder, P. Serrano Galvez, L.S. Stoel, C. Zamantzas, V. Zhovkovska
CERN, Meyrin, Switzerland
F.M. Addesa, F. Iacoangeli
INFN-Roma, Roma, Italy
A.G. Afonin, Y.A. Chesnokov, A.A. Durum, V.A. Maisheev, Yu.E. Sandomirskiy, A.A. Yanovich
IHEP, Moscow Region, Russia
J.E. Borg, M. Garattini, G. Hall, T. James, M. Pesaresi
Imperial College of Science and Technology, Department of Physics, London, United Kingdom
A.S. Denisov, Y. Gavrikov, Yu.M. Ivanov, M.A. Koznov, L.G. Malyarenko, V. Skorobogatov
PNPI, Gatchina, Leningrad District, Russia
F. Galluccio
INFN-Napoli, Napoli, Italy
F. Murtas
INFN/LNF, Frascati, Italy

A proof-of-principle experiment demonstrating the feasibility of using a thin, bent crystal aligned upstream of an extraction septum (ES) to increase the efficiency of the third-integer resonant slow extraction process has been carried out at the CERN Super Proton Synchrotron (SPS). With the primary aim of reducing the beam loss and induced radio-activation of the SPS, the crystal was aligned to both the beam and the septum to reduce by up to 40% the beam intensity impinging the ES and increase the intensity entering the external transfer line. In this contribution, we introduce the concept and the prototype system that was installed in 2018 before reporting in detail on the dedicated program of machine development studies carried out to characterise its performance and demonstrate operational feasibility. The performance reach and compatibility with other loss reduction techniques proposed to further increase the extraction efficiency, such as phase space folding with octupoles, is discussed in view of future high intensity operation.

Slides THXXPLM2 [1.397 MB]

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THPGW057

HL-LHC Full Remote Alignment Study

3716

A. Herty, R. De Maria, P. Fessia, D. Gamba, M. Giovannozzi, J. Hansen, I. Lamas Garcia, H. Mainaud Durand, S. Redaelli
CERN, Meyrin, Switzerland

Funding: Research supported by the HL-LHC project.
This study explores the benefits of extending the monitoring and remote alignment concept, proposed in the HL-LHC baseline, to additional components of the matching sections of the HL-LHC. The objective was to evaluate the benefits in terms of equipment performance and new opportunities for system simplification. In collaboration with the HL-LHC Working Group on Alignment, critical input parameters such as ground motion, manufacturing, assembly, and alignment tolerances, have been quantified. Solutions for the selected, manually aligned compo-nents have been investigated with the particular focus on vacuum design, mechanical design and the new alignment concept compatible with reliability and maintainability requirements. In this context, collimators and masks are key elements to be included in the extended alignment system. Their supporting systems will integrate the concept of on-line monitoring sensors and an actuator based, remote alignment platform. The full remote alignment of components will provide a positive impact to the machine operation reducing the need of human intervention in the tunnel and providing enhanced flexibility to perform the required alignment adjustment as part of an operational tool for the HL-LHC.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW057

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paper received ※ 09 May 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019

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THPRB031

Operational Performance of the Machine Protection Systems of the Large Hadron Collider During Run 2 and Lessons Learnt for the LIU/HL-LHC Era

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M. Zerlauth, A. Antoine, W. Bartmann, C. Bracco, E. Carlier, Z. Charifoulline, R. Denz, B. Goddard, A. Lechner, N. Magnin, C. Martin, R. Mompo, S. Redaelli, I. Romera, B. Salvachua, R. Schmidt, J.A. Uythoven, A.P. Verweij, J. Wenninger, C. Wiesner, D. Wollmann, C. Zamantzas
CERN, Geneva, Switzerland

The Large Hadron Collider (LHC) has successfully completed its second operational run of four years length in December 2018. Operation will be stopped during two years for maintenance and upgrades. To allow for the successful completion of the diverse physics program at 6.5 TeV, the LHC has been routinely operating with stored beam energies close to 300 MJ per beam during high intensity proton runs as well as being frequently reconfigured to allow for special physic runs and important machine developments. No significant damage has incurred to the protected accelerator equipment throughout the run thanks to the excellent performance of the various machine protection systems, however a number of important observations and new failure scenarios have been identified, which were studied experimentally as well as through detailed simulations. In this contribution, we provide an overview of the performance of the machine protection systems throughout Run 2 as well as the important lessons learnt that will impact consolidation actions and the upgrade of the machine protection systems for the LIU/HL-LHC era.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB031

About •

paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)