IPAC2019 - List of Authors (Goddard, B.)

Paper	Title	Page
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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MOPRB052	Gamma Factory at CERN: Design of a Proof-of-Principle Experiment	685
	Y. Dutheil, R. Alemany-Fernández, H. Bartosik, N. Biancacci, R. Bruce, P. Czodrowski, V. Fedosseev, B. Goddard, S. Hirlaender, J.M. Jowett, R. Kersevan, M. Kowalska, M. Lamont, D. Manglunki, J. Molson, A.V. Petrenko, M. Schaumann, F. Zimmermann CERN, Meyrin, Switzerland S.E. Alden, A. Bosco, S.M. Gibson, L.J. Nevay JAI, Egham, Surrey, United Kingdom A. Apyan ANSL, Yerevan, Armenia E.G. Bessonov LPI, Moscow, Russia A. Bosco, S.M. Gibson, L.J. Nevay Royal Holloway, University of London, Surrey, United Kingdom F. Castelli Università degli Studi di Milano, Milano, Italy F. Castelli, C. Curatolo, L. Serafini INFN-Milano, Milano, Italy K. Kroeger FSU Jena, Jena, Germany A. Martens LAL, Orsay, France V. Petrillo Universita’ degli Studi di Milano, Milano, Italy M. Sapinski, T. Stöhlker GSI, Darmstadt, Germany G. Weber IOQ, Jena, Germany Y.K. Wu FEL/Duke University, Durham, North Carolina, USA
	The Gamma Factory (GF) initiative proposes to create novel research tools at CERN by producing, accelerating and storing highly relativistic partially stripped ion beams in the LHC rings and by exciting their atomic degrees of freedom by lasers, to produce high-energy photon beams. Their intensity would be several orders of magnitude higher than those of the presently operating light sources in the particularly interesting gamma-ray energy domain reaching up to 400 MeV. In this energy domain, the high-intensity photon beams can be used to produce secondary beams of polarized electrons, polarized positrons, polarized muons, neutrinos, neutrons and radioactive ions. Over the years 2017-2018 we have demonstrated that these partially stripped ion beams can be successfully produced, accelerated and stored in the CERN accelerator complex, including the LHC. The next step of the project is to build a proof of principle experiment in the SPS to validate the principal GF concepts. This contribution will present the initial conceptual design of this experiment along with its main challenge - the demonstration of the fast cooling method of partially stripped ion beams.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB052
About •	paper received ※ 19 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPTS098	A Primary Electron Beam Facility at CERN	1098
	Y. Papaphilippou, R. Corsini, Y. Dutheil, L.R. Evans, B. Goddard, A. Grudiev, A. Latina, S. Stapnes CERN, Geneva, Switzerland T.P.Å. Åkesson Lund University, Department of Physics, Lund, Sweden
	This paper describes the concept of a primary electron beam facility at CERN, to be used for dark gauge force and light dark matter searches. The electron beam is produced in three stages: A Linac accelerates electrons from a photo-cathode up to 3.5 GeV. This beam is injected into the Super Proton Synchrotron, SPS, and accelerated up to a maximum energy of 16 GeV. Finally, the accelerated beam is slowly extracted to an experiment, possibly followed by a fast dump of the remaining electrons to another beamline. The beam parameters are optimized using the requirements of the Light Dark Matter eXperiment, LDMX, as benchmark.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS098
About •	paper received ※ 15 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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WEPMP024	Alternative Material Choices to Reduce Activation of Extraction Equipment	2363
	D. Björkman, B. Balhan, J.C.C.M. Borburgh, L.S. Esposito, M.A. Fraser, B. Goddard, L.S. Stoel, H. Vincke CERN, Meyrin, Switzerland
	At CERN, the Super Proton Synchrotron (SPS) is equipped with a resonant slow extraction system in Long Straight Section 2 (LSS2) towards the fixed target (FT) beam lines in the North Area. The extraction region provides the physics experiments with a quasi-DC flux of high-energy protons over a few seconds, which corresponds to tens of thousands of turns. The resonant slow extraction process provokes beam losses and is therefore the origin of radiation damage and the production of induced radioactivity in this region of the machine. This induced radioactivity imposed high constraints on the equipment design to be reliable to minimise the radiation exposure to personnel during machine maintenance. A detailed FLUKA model was developed in order to better understand the beam loss patterns, activation of the machine and to identify equipment components that could be optimised to reduce the residual dose related hazards. Simulations identified multiple alternative materials for extraction equipment components as well as shielding locations, which implementation could reduce residual activation hazards.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPMP024
About •	paper received ※ 26 April 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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WEPMP027	Update on Beam Transfer Line Design for the SPS Beam Dump Facility	2375
	Y. Dutheil, J. Bauche, L.A. Dougherty, M.A. Fraser, B. Goddard, C. Heßler, V. Kain, J. Kurdej, J.A. Uythoven, F.M. Velotti CERN, Meyrin, Switzerland
	The SPS Beam Dump Facility (BDF) being studied as part of the Physics Beyond Colliders (PBC) CERN project has recently reached an important milestone with the completion of the comprehensive feasibility study. The BDF is a proposed fixed target facility to be installed in the SPS North Area, to accommodate experiments such as SHiP (Search for Hidden Particles), which is most notably aiming at studying hidden sector particles. This experiment requires a high intensity slowly extracted 400 GeV proton beam with 4·10¹³ protons per 1 s spill to achieve 4·10¹⁹ protons on target per year. The extraction and transport scheme will make use of the first 600 m of the existing North Area extraction line. This contribution presents the status of the design work of the new transfer line and discusses the challenges identified. Aperture studies and failure scenarios are treated and the results discussed. In particular, interlock systems aiming at protecting critical components against the uncontrolled loss of the high energy proton beam are considered. We also present the latest results and implications of the design of a new laminated Lambertson splitter magnet to provide fast switching between the current North Area experiments and the BDF.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPMP027
About •	paper received ※ 13 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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WEPMP028	Crystal for Slow Extraction Loss-Reduction of the SPS Electrostatic Septum	2379
	L.S. Esposito, P. Bestman, M.E.J. Butcher, M. Calviani, M. Di Castro, M. Donzé, M.A. Fraser, M. Garattini, Y. Gavrikov, S.S. Gilardoni, B. Goddard, V. Kain, J. Lendaro, A. Masi, M. Pari, J. Prieto, R. Rossi, W. Scandale, R. Seidenbinder, P. Serrano Galvez, L.S. Stoel, F.M. Velotti, 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 A.D. Kovalenko, A.M. Taratin JINR, Dubna, Moscow Region, Russia F. Murtas INFN/LNF, Frascati, Italy A. Natochii LAL, Orsay, France
	The use of a bent crystal was investigated in order to reduce the losses at the CERN Super Proton Synchrotron (SPS) electrostatic septa (ZS) during the slow extraction of 400 GeV protons toward the North Area. The crystal, installed a few meters upstream the ZS, bends protons that would otherwise impinge on the ZS wires. Since particle deflection with good efficiency is achieved only when the crystal lattice is aligned within ~10 urad to the trajectory of the particles (at p = 400 GeV/c), a compact goniometer was built to allow the correct angular alignment of the crystal with respect to the incoming beam with a precision of few urad. In this paper, we report on the crystal features measured during a dedicated beam test by the UA9 experimental installation in the CERN H8 beam line. Details of the goniometer and its installation are also reported. The first results achieved during dedicated Machine Development (MD) sessions are finally presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPMP028
About •	paper received ※ 14 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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WEPMP029	Systematic Optics Studies for the Commissioning of the AWAKE Beamline	2383
	C. Bracco, B. Goddard, I. Gorgisyan, M. Turner, F.M. Velotti, L. Verra CERN, Meyrin, Switzerland M. Aiba PSI, Villigen PSI, Switzerland
	The commissioning of the AWAKE electron beam line was successfully completed in 2018. Despite a modest length of about 15 m, this low-energy line is quite complex and several iterations were needed before finding satisfactory agreement between the model and the measurements. The work allowed to precisely predict the size and positioning of the electron beam at the merging point with the protons inside the plasma cell, where no direct measurement is possible. All the key aspects and corrections which had to be included in the model, precautions and systematic checks to apply for the correct setup of the line are presented. The sensitivity of the ~18 MeV electron beam to various perturbations, like different initial optics parameters and beam conditions, energy jitter and drifts, earth’s magnetic field etc., is described.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPMP029
About •	paper received ※ 10 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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WEPMP030	LHC Injection Losses and Trajectories During Run 1 and 2 and Outlook to Injection of HL-LHC Beams	2387
	W. Bartmann, C. Bracco, B. Goddard, F.M. Velotti, J. Wenninger CERN, Meyrin, Switzerland
	The LHC turn-around time is impacted by the control of injection losses and trajectories. While shot-to-shot trajectory variations dominated the injection efficiency during LHC Run 1, several improvements of hardware and operational settings allowed for a high rate of successful injections during Run 2. Injection losses and trajectories are analysed and presented for the high intensity proton runs, as well as for different beam types used from the injectors. Based on this analysis, an outlook is shown for the HL-LHC era, where double the bunch intensity will have to be injected.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPMP030
About •	paper received ※ 14 May 2019 paper accepted ※ 23 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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WEPMP032	Tracking Simulations of Shadowing Electrostatic Septum Wires by Means of Bent Crystals	2395
	F.M. Velotti, M.A. Fraser, B. Goddard, V. Kain, L.S. Stoel CERN, Meyrin, Switzerland
	The Super Proton Synchrotron (SPS) slow extraction is a third integer resonant extraction and hence suffers from high losses at the electrostatic septum (ZS). This is one of the main limiting factors for the maximum number of Protons On Target (POT) deliverable from the SPS to the North Area (NA). A concept to significantly reduce the extraction losses via shadowing of the electrostatic septum wires using an upstream bent crystal has been proposed in , predicting a loss reduction of up to 50% for the prototype system installed in 2018. Following the successful experimental demonstration of the concept with beam , detailed tracking simulations have been performed to fully understand the results obtained. Further insights, such as the effective ZS width and its alignment, could be deduced by exploiting the response of the extraction loss as a function of the two degrees of freedom of the crystal (position and angle). In this paper, the beam dynamics simulations are discussed together with the implementation of the bent crystal into the simulation framework. A comparison with measurements is presented before proposals for new configurations and parameters are discussed. F.M. Velotti, et al., "Reduction of Resonant Slow Extraction Losses…", IPAC’18. ** F.M. Velotti, M.A. Fraser, et al., "Experimental SPS Slow Extraction Loss Reduction…", this conf.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPMP032
About •	paper received ※ 15 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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WEPMP033	Slow Extraction Loss Reduction With Octupoles at the CERN SPS	2399
	L.S. Stoel, H. Bartosik, M. Benedikt, M.A. Fraser, B. Goddard, V. Kain, F.M. Velotti CERN, Meyrin, Switzerland
	The powering of octupoles during third-integer resonant slow extraction has been studied and recently tested with beam at the CERN Super Proton Synchrotron (SPS) in order to increase the extraction efficiency and reduce the induced radioactivity of the extraction straight. The octupoles distort the particle trajectories in phase space in such a way that the extracted separatrix is folded, which decreases the particle density impinging the wires of the extraction septum at the expense of increasing the extracted beam emittance. During experimental SPS machine studies a reduction of over 40% in the specific (per extracted proton) beam loss measured at the extraction septum was demonstrated. In this paper, the prerequisite studies needed to safely but efficiently deploy the new extraction scheme in a limited time-frame are described, the experimental results are presented and an outlook is given towards the next steps to bring slow extraction with octupoles into routine operation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPMP033
About •	paper received ※ 14 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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WEPMP034	Characterisation of SPS Slow Extraction Spill Quality Degradation	2403
	F.M. Velotti, H. Bartosik, M.C.L. Buzio, K. Cornelis, V. Di Capua, M.A. Fraser, B. Goddard, V. Kain CERN, Meyrin, Switzerland
	The main physics users of the Super Proton Synchrotron (SPS) are the experiments installed in the North Area (NA). They are supplied with slowly extracted protons or heavy ions, exploiting a third integer slow extraction to provide a 4.8 s spill. High duty cycle and constant particle flux are the main requirements. Frequent super cycle changes induce variation of the spill macro structure which directly deteriorate the final spill quality. In this paper, the source of such an effect are investigated. Results of both beam based measurements and direct magnetic measurements on the SPS reference magnets are presented. Finally, a possible strategy to counteract this effect is discussed, in order to try to remove the super cycle changes variation as cause for spill quality deterioration.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPMP034
About •	paper received ※ 15 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019
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WEPMP035	Model and Measurements of CERN-SPS Slow Extraction Spill Re-Shaping - the Burst Mode Slow Extraction	2406
	M. Pari, M.A. Fraser, B. Goddard, V. Kain, L.S. Stoel, F.M. Velotti CERN, Meyrin, Switzerland
	The ENUBET ("Enhanced NeUtrino BEams from kaon Tagging") Project aims at reaching a new level of precision of the short-baseline neutrino cross section measurement by using an instrumented decay tunnel. The North Area (NA) experimental facility of the Super Proton Synchrotron (SPS) offers the required infrastructure for the experiment. A new slow extraction type, consisting of bursts of many consecutive millisecond spills within one macro spill, has been modeled and tested for the ENUBET Project. The burst-mode slow extraction has been tested for the first time at CERN-SPS, and MADX simulations of the process have been developed. In this paper the experimental results obtained during the test campaign are presented along with the results of the quality of the produced spill and comparing it with predictions from simulations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPMP035
About •	paper received ※ 12 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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WEPMP040	Machine Protection Aspects of High-Voltage Flashovers of the LHC Beam Dump Dilution Kickers	2418
	C. Wiesner, W. Bartmann, C. Bracco, M. Calviani, E. Carlier, L. Ducimetière, M.I. Frankl, M.A. Fraser, S.S. Gilardoni, B. Goddard, V. Gomes Namora, T. Kramer, A. Lechner, N. Magnin, M. Meddahi, A. Perillo-Marcone, T. Polzin, L.C. Richtmann, V. Rizzoglio, V. Senaj, J.A.F. Somoza, D. Wollmann CERN, Meyrin, Switzerland
	The LHC Beam Dump System is required to safely dispose of the energy of the stored beam. In order to reduce the energy density deposited in the beam dump, a dedicated dilution system is installed. On July 14, 2018, during a regular beam dump at 6.5 TeV beam energy, a high-voltage flashover of two vertical dilution kickers was observed, leading to a voltage breakdown and reduced dilution in the vertical plane. It was the first incident of this type since the start of LHC beam operation. In this paper, the flashover event is described and the implications analysed. Circuit simulations of the current in the magnet coil as well as simulations of the resulting beam sweep pattern are presented and compared with the measurements. The criticality of the event is assessed and implications for future failure scenarios are discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPMP040
About •	paper received ※ 14 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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THXPLM1	LHC Injectors Upgrade Project: Towards New Territory Beam Parameters	3385
	M. Meddahi, R. Alemany-Fernández, H. Bartosik, G. Bellodi, J. Coupard, H. Damerau, G.P. Di Giovanni, F.B. Dos Santos Pedrosa, A. Funken, B. Goddard, K. Hanke, A. Huschauer, V. Kain, A.M. Lombardi, B. Mikulec, S. Prodon, G. Rumolo, R. Scrivens, E.N. Shaposhnikova CERN, Geneva, Switzerland
	The LHC injectors Upgrade (LIU) project aims at increasing the intensity and brightness in the LHC injectors in order to match the challenging requirements of the High-Luminosity LHC (HL-LHC) project, while ensuring high availability and reliable operation of the injectors complex up to the end of the HL-LHC era (ca. 2035). This requires extensive hardware modifications and new beam dynamics solutions in the entire LHC proton and ion injection chains: the new Linac4, the Proton Synchrotron Booster, the Proton Synchrotron the Super Proton Synchrotron together with the ion PS injectors (the Linac3 and the Low Energy Ion Ring). All hardware modifications will be implemented during the 2019-2020 CERN accelerators shutdown. This talk would analyze the various project phases, share the lessons learned, and conclude on the expected beam parameter reach, together with the related risks.
	Slides THXPLM1 [20.029 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THXPLM1
About •	paper received ※ 14 May 2019 paper accepted ※ 22 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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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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THPRB072	Operational Experience of a Prototype LHC Injection Kicker Magnet with a Low SEY Coating and Redistributed Power Deposition	3974
	M.J. Barnes, C. Bracco, G. Bregliozzi, A. Chmielinska, L. Ducimetière, B. Goddard, G. Iadarola, T. Kramer, V. Vlachodimitropoulos, W.J.M. Weterings CERN, Geneva, Switzerland A. Chmielinska EPFL, Lausanne, Switzerland L. Vega Cid ETSII UPM, Madrid, Spain
	Funding: This research was supported by the HL-LHC project In the event that it is necessary to exchange an LHC injection kicker magnet (MKI), the newly installed kicker magnet would limit HL-LHC operation for a few hundred hours due to dynamic vacuum activity. A surface coating with a low secondary electron yield, applied to the inner surface of an alumina tube to reduce dynamic vacuum activity without increasing the probability of UFOs, and which is compatible with the high voltage environment, was included in a prototype MKI installed in the LHC during the 2017-18 Year End Technical Stop. In addition, this MKI included an upgrade to relocate a significant portion of beam induced power from the yoke to a ’damping element’: this element is not at pulsed high voltage. The effectiveness of the upgrades has been demonstrated during LHC operation, hence a future version will include water cooling of this ’damping element’. This paper reviews dynamic vacuum around the MKIs and summarizes operational experience of the upgraded MKI.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB072
About •	paper received ※ 08 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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THPRB080	Automatisation of the SPS ElectroStatic Septa Alignment	4001
	S. Hirlaender ATI, Vienna, Austria M.A. Fraser, B. Goddard, V. Kain, J. Prieto, L.S. Stoel, F.M. Velotti CERN, Meyrin, Switzerland M. Szakaly Wigner Research Centre for Physics, Institute for Particle and Nuclear Physics, Budapest, Hungary
	An electrostatic septum composed of 5 separate tanks is used to slow-extract the 400 GeV proton beam resonantly on the third integer resonance from the CERN SPS. The septa are all mounted on a single support structure that can move the ensemble coherently and, in addition, the internal anode and cathode of each tank can be moved independently. The septum is aligned to the beam by measuring and minimising the induced beam loss signals in the extraction region following an alignment procedure that is usually carried out manually at the beginning of each year. The large number of positional degrees of freedom complicates the procedure and until recently each tank was aligned one after the other semi-manually, typically requiring 8 hours. It is not uncommon that the septum has to be re-aligned later in the run taking time away from physics programme. To tackle this issue, a simplified beam dynamics and scattering simulation routine was developed to permit error studies with a large number of seeds to be carried out in a reasonable computation time. In this contribution, the simulation model will be described before the results of its exploitation to understand the efficacy of alignment procedures based on different optimization algorithms are discussed and compared to the present operational procedure. The effort culminated with the implementation of an automated alignment procedure based on a Powell optimisation algorithm that reduced the time needed to align the septum by over an order of magnitude.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB080
About •	paper received ※ 14 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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Paper

Title

Page

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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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP037

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

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MOPRB052

Gamma Factory at CERN: Design of a Proof-of-Principle Experiment

685

Y. Dutheil, R. Alemany-Fernández, H. Bartosik, N. Biancacci, R. Bruce, P. Czodrowski, V. Fedosseev, B. Goddard, S. Hirlaender, J.M. Jowett, R. Kersevan, M. Kowalska, M. Lamont, D. Manglunki, J. Molson, A.V. Petrenko, M. Schaumann, F. Zimmermann
CERN, Meyrin, Switzerland
S.E. Alden, A. Bosco, S.M. Gibson, L.J. Nevay
JAI, Egham, Surrey, United Kingdom
A. Apyan
ANSL, Yerevan, Armenia
E.G. Bessonov
LPI, Moscow, Russia
A. Bosco, S.M. Gibson, L.J. Nevay
Royal Holloway, University of London, Surrey, United Kingdom
F. Castelli
Università degli Studi di Milano, Milano, Italy
F. Castelli, C. Curatolo, L. Serafini
INFN-Milano, Milano, Italy
K. Kroeger
FSU Jena, Jena, Germany
A. Martens
LAL, Orsay, France
V. Petrillo
Universita’ degli Studi di Milano, Milano, Italy
M. Sapinski, T. Stöhlker
GSI, Darmstadt, Germany
G. Weber
IOQ, Jena, Germany
Y.K. Wu
FEL/Duke University, Durham, North Carolina, USA

The Gamma Factory (GF) initiative proposes to create novel research tools at CERN by producing, accelerating and storing highly relativistic partially stripped ion beams in the LHC rings and by exciting their atomic degrees of freedom by lasers, to produce high-energy photon beams. Their intensity would be several orders of magnitude higher than those of the presently operating light sources in the particularly interesting gamma-ray energy domain reaching up to 400 MeV. In this energy domain, the high-intensity photon beams can be used to produce secondary beams of polarized electrons, polarized positrons, polarized muons, neutrinos, neutrons and radioactive ions. Over the years 2017-2018 we have demonstrated that these partially stripped ion beams can be successfully produced, accelerated and stored in the CERN accelerator complex, including the LHC. The next step of the project is to build a proof of principle experiment in the SPS to validate the principal GF concepts. This contribution will present the initial conceptual design of this experiment along with its main challenge - the demonstration of the fast cooling method of partially stripped ion beams.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB052

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paper received ※ 19 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPTS098

A Primary Electron Beam Facility at CERN

1098

Y. Papaphilippou, R. Corsini, Y. Dutheil, L.R. Evans, B. Goddard, A. Grudiev, A. Latina, S. Stapnes
CERN, Geneva, Switzerland
T.P.Å. Åkesson
Lund University, Department of Physics, Lund, Sweden

This paper describes the concept of a primary electron beam facility at CERN, to be used for dark gauge force and light dark matter searches. The electron beam is produced in three stages: A Linac accelerates electrons from a photo-cathode up to 3.5 GeV. This beam is injected into the Super Proton Synchrotron, SPS, and accelerated up to a maximum energy of 16 GeV. Finally, the accelerated beam is slowly extracted to an experiment, possibly followed by a fast dump of the remaining electrons to another beamline. The beam parameters are optimized using the requirements of the Light Dark Matter eXperiment, LDMX, as benchmark.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS098

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paper received ※ 15 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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WEPMP024

Alternative Material Choices to Reduce Activation of Extraction Equipment

2363

D. Björkman, B. Balhan, J.C.C.M. Borburgh, L.S. Esposito, M.A. Fraser, B. Goddard, L.S. Stoel, H. Vincke
CERN, Meyrin, Switzerland

At CERN, the Super Proton Synchrotron (SPS) is equipped with a resonant slow extraction system in Long Straight Section 2 (LSS2) towards the fixed target (FT) beam lines in the North Area. The extraction region provides the physics experiments with a quasi-DC flux of high-energy protons over a few seconds, which corresponds to tens of thousands of turns. The resonant slow extraction process provokes beam losses and is therefore the origin of radiation damage and the production of induced radioactivity in this region of the machine. This induced radioactivity imposed high constraints on the equipment design to be reliable to minimise the radiation exposure to personnel during machine maintenance. A detailed FLUKA model was developed in order to better understand the beam loss patterns, activation of the machine and to identify equipment components that could be optimised to reduce the residual dose related hazards. Simulations identified multiple alternative materials for extraction equipment components as well as shielding locations, which implementation could reduce residual activation hazards.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPMP024

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paper received ※ 26 April 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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WEPMP027

Update on Beam Transfer Line Design for the SPS Beam Dump Facility

2375

Y. Dutheil, J. Bauche, L.A. Dougherty, M.A. Fraser, B. Goddard, C. Heßler, V. Kain, J. Kurdej, J.A. Uythoven, F.M. Velotti
CERN, Meyrin, Switzerland

The SPS Beam Dump Facility (BDF) being studied as part of the Physics Beyond Colliders (PBC) CERN project has recently reached an important milestone with the completion of the comprehensive feasibility study. The BDF is a proposed fixed target facility to be installed in the SPS North Area, to accommodate experiments such as SHiP (Search for Hidden Particles), which is most notably aiming at studying hidden sector particles. This experiment requires a high intensity slowly extracted 400 GeV proton beam with 4·10¹³ protons per 1 s spill to achieve 4·10¹⁹ protons on target per year. The extraction and transport scheme will make use of the first 600 m of the existing North Area extraction line. This contribution presents the status of the design work of the new transfer line and discusses the challenges identified. Aperture studies and failure scenarios are treated and the results discussed. In particular, interlock systems aiming at protecting critical components against the uncontrolled loss of the high energy proton beam are considered. We also present the latest results and implications of the design of a new laminated Lambertson splitter magnet to provide fast switching between the current North Area experiments and the BDF.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPMP027

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paper received ※ 13 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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WEPMP028

Crystal for Slow Extraction Loss-Reduction of the SPS Electrostatic Septum

2379

L.S. Esposito, P. Bestman, M.E.J. Butcher, M. Calviani, M. Di Castro, M. Donzé, M.A. Fraser, M. Garattini, Y. Gavrikov, S.S. Gilardoni, B. Goddard, V. Kain, J. Lendaro, A. Masi, M. Pari, J. Prieto, R. Rossi, W. Scandale, R. Seidenbinder, P. Serrano Galvez, L.S. Stoel, F.M. Velotti, 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
A.D. Kovalenko, A.M. Taratin
JINR, Dubna, Moscow Region, Russia
F. Murtas
INFN/LNF, Frascati, Italy
A. Natochii
LAL, Orsay, France

The use of a bent crystal was investigated in order to reduce the losses at the CERN Super Proton Synchrotron (SPS) electrostatic septa (ZS) during the slow extraction of 400 GeV protons toward the North Area. The crystal, installed a few meters upstream the ZS, bends protons that would otherwise impinge on the ZS wires. Since particle deflection with good efficiency is achieved only when the crystal lattice is aligned within ~10 urad to the trajectory of the particles (at p = 400 GeV/c), a compact goniometer was built to allow the correct angular alignment of the crystal with respect to the incoming beam with a precision of few urad. In this paper, we report on the crystal features measured during a dedicated beam test by the UA9 experimental installation in the CERN H8 beam line. Details of the goniometer and its installation are also reported. The first results achieved during dedicated Machine Development (MD) sessions are finally presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPMP028

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paper received ※ 14 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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WEPMP029

Systematic Optics Studies for the Commissioning of the AWAKE Beamline

2383

C. Bracco, B. Goddard, I. Gorgisyan, M. Turner, F.M. Velotti, L. Verra
CERN, Meyrin, Switzerland
M. Aiba
PSI, Villigen PSI, Switzerland

The commissioning of the AWAKE electron beam line was successfully completed in 2018. Despite a modest length of about 15 m, this low-energy line is quite complex and several iterations were needed before finding satisfactory agreement between the model and the measurements. The work allowed to precisely predict the size and positioning of the electron beam at the merging point with the protons inside the plasma cell, where no direct measurement is possible. All the key aspects and corrections which had to be included in the model, precautions and systematic checks to apply for the correct setup of the line are presented. The sensitivity of the ~18 MeV electron beam to various perturbations, like different initial optics parameters and beam conditions, energy jitter and drifts, earth’s magnetic field etc., is described.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPMP029

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paper received ※ 10 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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WEPMP030

LHC Injection Losses and Trajectories During Run 1 and 2 and Outlook to Injection of HL-LHC Beams

2387

W. Bartmann, C. Bracco, B. Goddard, F.M. Velotti, J. Wenninger
CERN, Meyrin, Switzerland

The LHC turn-around time is impacted by the control of injection losses and trajectories. While shot-to-shot trajectory variations dominated the injection efficiency during LHC Run 1, several improvements of hardware and operational settings allowed for a high rate of successful injections during Run 2. Injection losses and trajectories are analysed and presented for the high intensity proton runs, as well as for different beam types used from the injectors. Based on this analysis, an outlook is shown for the HL-LHC era, where double the bunch intensity will have to be injected.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPMP030

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paper received ※ 14 May 2019 paper accepted ※ 23 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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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPMP031

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

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WEPMP032

Tracking Simulations of Shadowing Electrostatic Septum Wires by Means of Bent Crystals

2395

F.M. Velotti, M.A. Fraser, B. Goddard, V. Kain, L.S. Stoel
CERN, Meyrin, Switzerland

The Super Proton Synchrotron (SPS) slow extraction is a third integer resonant extraction and hence suffers from high losses at the electrostatic septum (ZS). This is one of the main limiting factors for the maximum number of Protons On Target (POT) deliverable from the SPS to the North Area (NA). A concept to significantly reduce the extraction losses via shadowing of the electrostatic septum wires using an upstream bent crystal has been proposed in *, predicting a loss reduction of up to 50% for the prototype system installed in 2018. Following the successful experimental demonstration of the concept with beam **, detailed tracking simulations have been performed to fully understand the results obtained. Further insights, such as the effective ZS width and its alignment, could be deduced by exploiting the response of the extraction loss as a function of the two degrees of freedom of the crystal (position and angle). In this paper, the beam dynamics simulations are discussed together with the implementation of the bent crystal into the simulation framework. A comparison with measurements is presented before proposals for new configurations and parameters are discussed.
* F.M. Velotti, et al., "Reduction of Resonant Slow Extraction Losses…", IPAC’18.
** F.M. Velotti, M.A. Fraser, et al., "Experimental SPS Slow Extraction Loss Reduction…", this conf.

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paper received ※ 15 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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WEPMP033

Slow Extraction Loss Reduction With Octupoles at the CERN SPS

2399

L.S. Stoel, H. Bartosik, M. Benedikt, M.A. Fraser, B. Goddard, V. Kain, F.M. Velotti
CERN, Meyrin, Switzerland

The powering of octupoles during third-integer resonant slow extraction has been studied and recently tested with beam at the CERN Super Proton Synchrotron (SPS) in order to increase the extraction efficiency and reduce the induced radioactivity of the extraction straight. The octupoles distort the particle trajectories in phase space in such a way that the extracted separatrix is folded, which decreases the particle density impinging the wires of the extraction septum at the expense of increasing the extracted beam emittance. During experimental SPS machine studies a reduction of over 40% in the specific (per extracted proton) beam loss measured at the extraction septum was demonstrated. In this paper, the prerequisite studies needed to safely but efficiently deploy the new extraction scheme in a limited time-frame are described, the experimental results are presented and an outlook is given towards the next steps to bring slow extraction with octupoles into routine operation.

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paper received ※ 14 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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WEPMP034

Characterisation of SPS Slow Extraction Spill Quality Degradation

2403

F.M. Velotti, H. Bartosik, M.C.L. Buzio, K. Cornelis, V. Di Capua, M.A. Fraser, B. Goddard, V. Kain
CERN, Meyrin, Switzerland

The main physics users of the Super Proton Synchrotron (SPS) are the experiments installed in the North Area (NA). They are supplied with slowly extracted protons or heavy ions, exploiting a third integer slow extraction to provide a 4.8 s spill. High duty cycle and constant particle flux are the main requirements. Frequent super cycle changes induce variation of the spill macro structure which directly deteriorate the final spill quality. In this paper, the source of such an effect are investigated. Results of both beam based measurements and direct magnetic measurements on the SPS reference magnets are presented. Finally, a possible strategy to counteract this effect is discussed, in order to try to remove the super cycle changes variation as cause for spill quality deterioration.

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

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WEPMP035

Model and Measurements of CERN-SPS Slow Extraction Spill Re-Shaping - the Burst Mode Slow Extraction

2406

M. Pari, M.A. Fraser, B. Goddard, V. Kain, L.S. Stoel, F.M. Velotti
CERN, Meyrin, Switzerland

The ENUBET ("Enhanced NeUtrino BEams from kaon Tagging") Project aims at reaching a new level of precision of the short-baseline neutrino cross section measurement by using an instrumented decay tunnel. The North Area (NA) experimental facility of the Super Proton Synchrotron (SPS) offers the required infrastructure for the experiment. A new slow extraction type, consisting of bursts of many consecutive millisecond spills within one macro spill, has been modeled and tested for the ENUBET Project. The burst-mode slow extraction has been tested for the first time at CERN-SPS, and MADX simulations of the process have been developed. In this paper the experimental results obtained during the test campaign are presented along with the results of the quality of the produced spill and comparing it with predictions from simulations.

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

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WEPMP040

Machine Protection Aspects of High-Voltage Flashovers of the LHC Beam Dump Dilution Kickers

2418

C. Wiesner, W. Bartmann, C. Bracco, M. Calviani, E. Carlier, L. Ducimetière, M.I. Frankl, M.A. Fraser, S.S. Gilardoni, B. Goddard, V. Gomes Namora, T. Kramer, A. Lechner, N. Magnin, M. Meddahi, A. Perillo-Marcone, T. Polzin, L.C. Richtmann, V. Rizzoglio, V. Senaj, J.A.F. Somoza, D. Wollmann
CERN, Meyrin, Switzerland

The LHC Beam Dump System is required to safely dispose of the energy of the stored beam. In order to reduce the energy density deposited in the beam dump, a dedicated dilution system is installed. On July 14, 2018, during a regular beam dump at 6.5 TeV beam energy, a high-voltage flashover of two vertical dilution kickers was observed, leading to a voltage breakdown and reduced dilution in the vertical plane. It was the first incident of this type since the start of LHC beam operation. In this paper, the flashover event is described and the implications analysed. Circuit simulations of the current in the magnet coil as well as simulations of the resulting beam sweep pattern are presented and compared with the measurements. The criticality of the event is assessed and implications for future failure scenarios are discussed.

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paper received ※ 14 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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THXPLM1

LHC Injectors Upgrade Project: Towards New Territory Beam Parameters

3385

M. Meddahi, R. Alemany-Fernández, H. Bartosik, G. Bellodi, J. Coupard, H. Damerau, G.P. Di Giovanni, F.B. Dos Santos Pedrosa, A. Funken, B. Goddard, K. Hanke, A. Huschauer, V. Kain, A.M. Lombardi, B. Mikulec, S. Prodon, G. Rumolo, R. Scrivens, E.N. Shaposhnikova
CERN, Geneva, Switzerland

The LHC injectors Upgrade (LIU) project aims at increasing the intensity and brightness in the LHC injectors in order to match the challenging requirements of the High-Luminosity LHC (HL-LHC) project, while ensuring high availability and reliable operation of the injectors complex up to the end of the HL-LHC era (ca. 2035). This requires extensive hardware modifications and new beam dynamics solutions in the entire LHC proton and ion injection chains: the new Linac4, the Proton Synchrotron Booster, the Proton Synchrotron the Super Proton Synchrotron together with the ion PS injectors (the Linac3 and the Low Energy Ion Ring). All hardware modifications will be implemented during the 2019-2020 CERN accelerators shutdown. This talk would analyze the various project phases, share the lessons learned, and conclude on the expected beam parameter reach, together with the related risks.

Slides THXPLM1 [20.029 MB]

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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

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paper received ※ 15 May 2019 paper accepted ※ 28 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.

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

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

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THPRB072

Operational Experience of a Prototype LHC Injection Kicker Magnet with a Low SEY Coating and Redistributed Power Deposition

3974

M.J. Barnes, C. Bracco, G. Bregliozzi, A. Chmielinska, L. Ducimetière, B. Goddard, G. Iadarola, T. Kramer, V. Vlachodimitropoulos, W.J.M. Weterings
CERN, Geneva, Switzerland
A. Chmielinska
EPFL, Lausanne, Switzerland
L. Vega Cid
ETSII UPM, Madrid, Spain

Funding: This research was supported by the HL-LHC project
In the event that it is necessary to exchange an LHC injection kicker magnet (MKI), the newly installed kicker magnet would limit HL-LHC operation for a few hundred hours due to dynamic vacuum activity. A surface coating with a low secondary electron yield, applied to the inner surface of an alumina tube to reduce dynamic vacuum activity without increasing the probability of UFOs, and which is compatible with the high voltage environment, was included in a prototype MKI installed in the LHC during the 2017-18 Year End Technical Stop. In addition, this MKI included an upgrade to relocate a significant portion of beam induced power from the yoke to a ’damping element’: this element is not at pulsed high voltage. The effectiveness of the upgrades has been demonstrated during LHC operation, hence a future version will include water cooling of this ’damping element’. This paper reviews dynamic vacuum around the MKIs and summarizes operational experience of the upgraded MKI.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB072

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paper received ※ 08 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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THPRB080

Automatisation of the SPS ElectroStatic Septa Alignment

4001

S. Hirlaender
ATI, Vienna, Austria
M.A. Fraser, B. Goddard, V. Kain, J. Prieto, L.S. Stoel, F.M. Velotti
CERN, Meyrin, Switzerland
M. Szakaly
Wigner Research Centre for Physics, Institute for Particle and Nuclear Physics, Budapest, Hungary

An electrostatic septum composed of 5 separate tanks is used to slow-extract the 400 GeV proton beam resonantly on the third integer resonance from the CERN SPS. The septa are all mounted on a single support structure that can move the ensemble coherently and, in addition, the internal anode and cathode of each tank can be moved independently. The septum is aligned to the beam by measuring and minimising the induced beam loss signals in the extraction region following an alignment procedure that is usually carried out manually at the beginning of each year. The large number of positional degrees of freedom complicates the procedure and until recently each tank was aligned one after the other semi-manually, typically requiring 8 hours. It is not uncommon that the septum has to be re-aligned later in the run taking time away from physics programme. To tackle this issue, a simplified beam dynamics and scattering simulation routine was developed to permit error studies with a large number of seeds to be carried out in a reasonable computation time. In this contribution, the simulation model will be described before the results of its exploitation to understand the efficacy of alignment procedures based on different optimization algorithms are discussed and compared to the present operational procedure. The effort culminated with the implementation of an automated alignment procedure based on a Powell optimisation algorithm that reduced the time needed to align the septum by over an order of magnitude.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB080

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paper received ※ 14 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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