01 Circular and Linear Colliders
A01 Hadron Colliders

Paper	Title	Page
MOYAA1	Approaching the Nominal Performance at the LHC	13
	J. Wenninger CERN, Geneva, Switzerland
	In 2015 the Large Hadron Collider (LHC) restarted for Run 2 after an almost two year long shutdown to consolidate the machine for operation at nominal beam energy. Following a month of recommissioning and training of the magnet system, the LHC operated for the first time at an energy of 6.5 TeV. The aim of this first year was to master operation at the higher energy and with beams of 25 ns spacing. In 2016 the performance could be pushed based on the experience of 2015, culminating with a luminosity 40% above the design value of 1034 cm-2s−1. The status of the machine operation, performance and prospects for the rest of Run 2 and Run 3 will be discussed.
	Slides MOYAA1 [4.639 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOYAA1
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TUPIK037	Proton Cross-Talk and Losses in the Dispersion Suppressor Regions at the FCC-hh	1763
	H. Rafique, R.B. Appleby UMAN, Manchester, United Kingdom J.L. Abelleira JAI, Oxford, United Kingdom A.M. Krainer, A. Langner CERN, Geneva, Switzerland
	Funding: The European Circular Energy-Frontier Collider Study (EuroCirCol), EU's Horizon 2020 grant No 654305 Protons that collide at the interaction points of the FCC-hh may contribute to the background in the subsequent detector. Due to the high luminosity of the proton beams this may be of concern. Using DPMJET-III to model 50 TeV proton-proton collisions, tracking studies have been performed with PTC and MERLIN in order to gauge the elastic and inelastic proton cross-talk. High arc losses, particularly in the dispersion suppressor regions, have been revealed. These losses originate mainly from particles with a momentum deviation, either from interaction with a primary collimator in the betatron cleaning insertion, or from the proton-proton collisions. This issue can be mitigated by introducing additional collimators in the dispersion suppressor region. The specific design, lattice integration, and the effect of these collimators on cross-talk is assessed.
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TUPIK089	Studies on Luminous Region, Pile-up and Performance for HL-LHC Scenarios	1908
SUSPSIK002	use link to see paper's listing under its alternate paper code
	L.E. Medina Medrano, G. Arduini, R. Tomás CERN, Geneva, Switzerland L.E. Medina Medrano UGTO, Leon, Mexico
	Funding: Research supported by the HL-LHC project and the Beam project (CONACYT, Mexico). Studies on luminous region and pile-up density are of great interest for the experiments at the future High Luminosity LHC (HL-LHC) in order to optimize the detector performance. The evolution of these parameters at the two main interaction points of the HL-LHC along optimum physics fills is studied for the baseline and alternative operational scenarios with the latest set of parameters, including a refined description of the longitudinal bunch profile. Results are discussed in terms of a new figure-of-merit, the effective pile-up density.
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TUPVA001	Progress on the Optics Corrections of FCC-hh	2019
	D. Boutin, A. Chancé, B. Dalena CEA/IRFU, Gif-sur-Yvette, France B.J. Holzer, D. Schulte CERN, Geneva, Switzerland
	The FCC-hh (Future Hadron-Hadron Circular Collider) is one of the three options considered for the next generation accelerator in high-energy physics as recommended by the European Strategy Group, and the natural evolution of existing LHC. Studies are ongoing about the evaluation of the various magnets mechanical errors and field errors tolerances in the arc sections of FCC-hh, as well as an estimation of the correctors strengths necessary to perform the corrections of the errors. In this study advanced correction schemes for the residual orbit, the linear coupling and the ring tune are described. The impact of magnet tolerances on the residual errors, on the correctors technological choice and on the beam screen design are discussed. In particular the effect of the dipole a2 error is emphasized.
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TUPVA002	Updates on the Optics of the Future Hadron-Hadron Collider FCC-hh	2023
	A. Chancé, D. Boutin, B. Dalena CEA/IRFU, Gif-sur-Yvette, France B.J. Holzer, A. Langner, D. Schulte CERN, Geneva, Switzerland
	Funding: The European Circular Energy-Frontier Collider Study (EuroCirCol) project has received funding from the European Union's Horizon 2020 research and innovation programme under grant No 654305. The FCC-hh (Future Hadron-Hadron Circular Collider) is one of the three options considered for the next generation accelerator in high-energy physics as recommended by the European Strategy Group. The layout of FCC-hh has been optimized to a more compact design following recommendations from civil engineering aspects. The updates on the first order and second order optics of the ring will be shown for collisions at the required centre-of-mass energy of 100 TeV. Special emphasis is put on the dispersion suppressors and general beam cleaning sections as well as first considerations of injection and extraction sections.
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TUPVA003	Advance on Dynamic Aperture at Injection for FCC-hh	2027
	B. Dalena, D. Boutin, A. Chancé CEA/IRFU, Gif-sur-Yvette, France B.J. Holzer, D. Schulte CERN, Geneva, Switzerland
	Funding: This Research and Innovation Action project submitted to call H2020-INFRADEV-1-2014-1 receives funding from the European Union's H2020 Framework Programme under grant agreement no. 654305. In the hadron machine option, proposed in the context of the Future Circular Colliders (FCC) study, the first evaluation of dipole field quality, based on the Nb3Sn technology, has shown a Dynamic Aperture at injection above the LHC target value. In this paper the effect of field imperfections on the dynamic aperture, using the updated lattice design, is presented. Tolerances on the main multipole components are evaluated including feed-down effect.
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TUPVA004	Synchrotron Radiation Backgrounds for the FCC-hh Experiments	2031
	F. Collamati INFN-Roma1, Rome, Italy M. Boscolo INFN/LNF, Frascati (Roma), Italy H. Burkhardt, R. Kersevan CERN, Geneva, Switzerland
	Funding: This work was supported by the HORIZON 2020 project EuroCirCol, grant agreement 654305. We present in this paper a detailed analysis of the synchrotron radiation emitted by the 50 TeV protons of the FCC-hh in the last bending and quadrupole magnets upstream the interaction region. We discuss the characteristics of this radiation in terms of power, flux, photon spectrum and fans in different running conditions such as, for example, with and without crossing angle. We mainly focus our study on the fraction of photons that may hit the detector, with a full tracking into GEANT4 that simulates their interaction within the central beam pipe.
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TUPVA005	Impact of the Crossing Angle on Luminosity Asymmetries at the LHC in 2016 Proton Physics Operation	2035
SUSPSIK001	use link to see paper's listing under its alternate paper code
	M. Hostettler LHEP, Bern, Switzerland F. Antoniou, I. Efthymiopoulos, K. Fuchsberger, G. Iadarola, N. Karastathis, M. Lamont, Y. Papaphilippou, G. Papotti, J. Wenninger CERN, Geneva, Switzerland
	During 2016 proton physics operation at the CERN Large Hadron Collider (LHC), an asymmetry of up to 10% was observed between the luminosities measured by the ATLAS and CMS experiments. As the same bunch pairs collide in both experiments, a difference in luminosities must be of either geometric or instrumental origin. This paper quantifies the impact of the crossing angle on this asymmetry. As the beams cross in different planes in the two experiments, non-round beams are expected to yield an asymmetry due to the crossing angle. Results from crossing angle measurements at both experiments are also shown and the impact on the luminosities is evaluated.
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TUPVA006	Lessons Learnt from the 2016 LHC Run and Prospects for HL-LHC Availability	2039
	A. Apollonio, O. Rey Orozko, R. Schmidt, M. Valette, D. Wollmann, M. Zerlauth CERN, Geneva, Switzerland
	The LHC exhibited unprecedented availability during the 2016 proton run, producing about 40 fb-1 of integrated luminosity, surpassing the sum of production during the 4 previous years. This was achieved while running steadily with a peak luminosity above the design target of 1034 cm- 2s−1. Individual system performance and an increased experience operating the LHC were fundamental for these achievements, following the consolidations and improvements deployed during the Long Shutdown 1 and the Year End Technical Stop in 2015. The implications of this excellent performance in the context of the High Luminosity LHC are discussed in this paper, with the goal of defining the possible integrated luminosity reach of HL-LHC when considering the different operating conditions and the newly developed systems and technologies.
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TUPVA007	Impact of LHC and SPS Injection Kicker Rise Times on Lhc Filling Schemes and Luminosity Reach	2043
	W. Bartmann, M.J. Barnes, J. Boyd, E. Carlier, A. Chmielinska, B. Goddard, G. Kotzian, C. Schwick, L.S. Stoel, D. Valuch, F.M. Velotti, V. Vlachodimitropoulos, C. Wiesner CERN, Geneva, Switzerland
	The 2016 LHC proton filling schemes generally used a spacing between injections of batches of bunches into SPS and LHC corresponding to the design report specification for the SPS and LHC injection kicker rise times, respectively. A reduction of the batch spacing can be directly used to increase luminosity without detrimental effects on beam stability, and with no increase in the number of events per crossing seen by the experiments. Measurements and simulations were performed in SPS and LHC to understand if a shorter injection kicker rise time and associated tighter batch spacing would lead to increased injection oscillations of the first and last bunches of a bunch train and eventually also a systematic growth of the transverse emittance. The results were used to define the minimum possible batch spacing for an acceptable emittance growth in LHC, with gains of reductions of about 10% possible in both machines. The results are discussed, including the potential improvement of the LHC luminosity for different filling schemes.
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TUPVA008	Assessment of Thermal Loads in the CERN SPS Crab Cavities Cryomodule	2047
	F. Carra, J. Apeland, R. Calaga, O. Capatina, T. Capelli, C. Zanoni CERN, Geneva, Switzerland S. Verdú-Andrés BNL, Upton, Long Island, New York, USA
	Funding: *Work supported by the European Union HL-LHC Project and by US DOE through Brookhaven Science Associates LLC under contract No. DE-AC02-98CH10886 and the US LHC Accelerator Research Program (LARP). Research supported by the HL-LHC project. As a part of the HL-LHC upgrade, a cryomodule is designed to host two crab cavities for a first test with protons in the SPS machine. The evaluation of the cryomodule heat loads is essential to dimension the cryogenic infrastructure of the system. The current design features two cryogenic circuits. The first circuit adopts superfluid helium at 2 K to maintain the cavities in the superconducting state. The second circuit, based on helium gas at a temperature between 50 K and 70 K, is connected to the thermal screen, also serving as heat intercept for all the interfaces between the cold mass and the external environment. An overview of the heat loads to both circuits, and the combined numerical and analytical estimations, is presented. The heat load of each element is detailed for the static and dynamic scenarios, with considerations on the design choices for the thermal optimization of the most critical components. #Federico.carra@cern.ch
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TUPVA009	Multiparametric Response of the LHC Dynamic Aperture in Presence of Beam-Beam Effects	2051
	D. Pellegrini, F. Antoniou, S.D. Fartoukh, G. Iadarola, Y. Papaphilippou CERN, Geneva, Switzerland
	We performed extended simulations of LHC dynamic aperture (DA) in the presence of beam-beam effects in the weak-strong approximation, evaluating the contributions of parameters such as: tunes, optics, bunch intensity, crossing angle, emittance, chromaticity and current in the Landau octupoles. Here we present a summary of these studies, giving an overview of the amplitude of the LHC operational space and pointing out the remaining margins for mitigation of instabilities. These studies supported the actions deployed during the 2016 run of the LHC, which aimed at maximising its performances. Examples of such actions are the switch to lower emittance beams, the reduction of crossing angle and tune trims. More recently, DA scans have been used to help the definition of the operational scenarios for the 2017 run. Additional room for improvements, for instance by deploying crossing angle levelling, will be explained.
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TUPVA010	Multiparametric Response of the HL-LHC Dynamic Aperture in Presence of Beam-Beam Effects	2055
	D. Pellegrini, S.D. Fartoukh, N. Karastathis, Y. Papaphilippou CERN, Geneva, Switzerland
	We performed extended simulations of HL-LHC dynamic aperture in the presence of beam-beam effects in the weak- strong approximation, evaluating the contributions of param- eters such as: bunch intensity, crossing angle, chromaticity, current in the Landau octupoles and multipole errors. From the beam dynamics point of view, the main differ- ence between the LHC (until 2017) and the HL-LHC is the deployment of the achromatic telescopic squeezing (ATS) optics, allowing not only for a smaller '' reach, but also modifying the phase advances between the lattice correctors (sextupoles, octupoles) and the main IPs, and increasing the peak ' functions in the arcs. These correctors become therefore more efficient for the chromatic correction, but also a mitigation of the beam-beam long range interactions using the Landau octupoles is enabled, resulting in a possible reduction of the normalised crossing angle. The limits have been investigated in a tracking simulation campaign aimed at exploring the operational space for the HL-LHC and two possible options for luminosity levelling.
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TUPVA011	Comparing Behaviour of Simulated Proton Synchrotron Radiation in the Arcs of the LHC with Measurements	2059
	G. Guillermo Cantón, M. Ady, R. Kersevan, F. Zimmermann CERN, Geneva, Switzerland M. Angelucci, R. Cimino, E. La Francesca INFN/LNF, Frascati (Roma), Italy D. Sagan Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: EuCARD2 CONACyT In previous work it was shown that at high proton-beam energies, synchrotron radiation is an important source of beam-screen heating, of beam-related vacuum pressure increase, and of primary photoelectrons, which can contribute to electron cloud formation. We have used the Synrad3D code developed at Cornell to simulate the photon distributions in the arcs of the LHC, HL-LHC, and FCC-hh. Specifically, for the LHC we studied the effect of the sawtooth chamber. In this paper specific results of the Synrad3D simulations are compared with simulations in Synrad+, developed at CERN; and later on compared with experimental data for actual LHC vacuum-chamber samples.
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TUPVA012	Beam Related Machine Protection of the Future Circular Collider	2063
	Y.C. Nie, M. Jonker, R. Schmidt CERN, Geneva, Switzerland
	In the Future Circular Collider (FCC) study, each nominal proton beam at top particle energy of 50 TeV has an energy of 8500 MJ, which is more than 20 times the energy of today's Large Hadron Collider (LHC) beam. Machine protection of such a high-energy and high-energy density accelerator becomes very challenging. In this paper, preliminary considerations of beam related machine protection issues of the FCC will be reported. Based on the current optics design, a few major critical equipment failures that could potentially lead to very fast (within a few turns) beam losses have been studied. The serious failure scenarios that have been considered, typically occurring at locations with high beta functions, include powering failures of normal conducting magnets, quenches of superconducting magnets as well as critical RF failures. Some fundamental questions related to the beam interlock system, e.g., the need for additional particle free abort gaps to shorten the synchronization time before executing a beam dump, will be discussed.
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TUPVA013	Lifetime of Asymmetric Colliding Beams in the LHC	2067
	J.M. Jowett, R. Alemany-Fernández, M.A. Jebramcik, T. Mertens, M. Schaumann CERN, Geneva, Switzerland
	In the 2013 proton-nucleus (p-Pb) run of the LHC, the lifetime of the lead beam was significantly shorter than could be accounted for by luminosity burn-off. These effects were observed at a lower level in 2016 and studied in more detail. The beams were not only asymmetric but the differences in the bunch filling schemes between protons and Pb nuclei led to a wide variety of beam-beam interaction sequences in the bunch trains. The colliding bunches were also of different sizes. We present an analysis of the data and an interpretation in terms of theoretical models.
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TUPVA014	The 2016 Proton-Nucleus Run of the LHC	2071
	J.M. Jowett, R. Alemany-Fernández, G. Baud, P. Baudrenghien, R. De Maria, R. De Maria, D. Jacquet, M.A. Jebramcik, A. Mereghetti, T. Mertens, M. Schaumann, H. Timko, M. Wendt, J. Wenninger CERN, Geneva, Switzerland
	For five of the LHC experiments the second p-Pb collision run planned in 2016 offered the opportunity to answer a range of important physics questions arising from the surprise discoveries (e.g., flow-like collective phenomena in small systems) made in earlier Pb-Pb, p-Pb and p-p runs. However the diversity of the physics and their respective capabilities led them to request very different operating conditions, in terms of collision energy, luminosity and pile-up. These appeared mutually incompatible within the available one month of operation. Nevertheless, a plan to satisfy most requirements was developed and implemented successfully. It exploited different beam lifetimes at two beam energies of 4 Z TeV and 6.5 Z TeV, a variety of luminosity sharing and bunch filling schemes, and varying beam directions. The outcome of this very complex strategy for repeated re-commissioning and operation of the LHC included the longest ever LHC fill with luminosity levelled for almost 38 h. The peak luminosity achieved exceeded the design value by a factor 7.8 and integrated luminosity substantially exceeded the experiments' requests.
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TUPVA015	Radiation Levels at the LHC: 2012, 2015 and 2016 Proton Physics Operations in View of HL-LHC requirements	2075
	C. Martinella, M. Brugger, S. Danzeca, R. Garcia Alia, Y. Kadi, O. Stein, C. Xu CERN, Geneva, Switzerland
	The variety of beam losses produced in the Large Hadron Collider (LHC) creates a mixed and complex radiation field. During 2012, 2015 and 2016, Beam Loss Monitors and RadMons were used to monitor the inte-grated dose and the High Energy Hadrons fluence in order to anticipate the electronics degradation and inves-tigate the cause of failures. The annual radiation levels are compared; highlighting the mechanisms in the pro-duction of beam losses and the impact of the different squeeze and crossing angle. In addition, the increase of beam-gas interaction is discussed comparing operations at 25 ns and 50 ns bunch spacing. A strategy is presented to allow for a continuous respective evaluation during the upcoming LHC and future High Luminosity LHC (HL-LHC) operations.
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TUPVA018	Macroparticle Simulation Studies of the LHC Beam Dynamics in the Presence of Electron Cloud	2081
SUSPSIK003	use link to see paper's listing under its alternate paper code
	A. Romano, G. Iadarola, K.S.B. Li, G. Rumolo CERN, Geneva, Switzerland
	Beam quality degradation caused by the Electron Cloud (EC) effects has been identified as one of the main performance limitations for the high intensity 25 ns beams in the Large Hadron Collider (LHC). When a proton bunch passes through an EC, electrons are attracted towards the transverse center of the beam resulting into an increasing electron density within the bunch. The effects driven by the interaction of the electrons with the bunch have been studied with macroparticle simulations in order to evaluate, in different operational scenarios, the threshold for the coherent instabilities as well as the incoherent tune spread. This contribution will summarize the main findings of the simulation study and compare them with the available experimental observations.
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TUPVA019	Impact and Mitigation of Electron Cloud Effects in the Operation of the Large Hadron Collider	2085
	G. Iadarola, B. Bradu, P. Dijkstal, L. Mether, G. Rumolo CERN, Geneva, Switzerland
	In 2015 and in 2016 the Large Hadron Collider has been routinely operated with 25 ns bunch spacing. With this beam configuration electron clouds develop in a large fraction of the beam chambers, in spite of a very large electron dose accumulated on the surfaces. This posed several challenges to different aspects of the beam operation. In particular, the machine settings had to be optimized in order to mitigate coherent and incoherent effects of the electron cloud on the beam dynamics while a specifically designed feed-forward control had to be implemented and optimized in order to dynamically adapt the regulations of the cryogenic system to the strong heat load deposited by the electron cloud on the beam screens of the cryogenic magnets. At the same time, the data collected from the different accelerator subsystems (heat loads, vacuum pressures, evolution of the bunch by bunch beam parameters) allowed to significantly improve our models and understanding on these phenomena.
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TUPVA021	Impact of Collision Debris in the HL-LHC ATLAS and CMS Insertions	2093
	A. Tsinganis, F. Cerutti CERN, Geneva, Switzerland
	The High Luminosity upgrade of the LHC (HL-LHC) foresees the baseline operation of the accelerator at a 5 times higher peak luminosity (5.0x1034cm-2s−1). The impact of collision debris on the magnets and other equipment in the triplet region and matching section of the ATLAS and CMS insertions has been evaluated by means of detailed FLUKA models implementing the latest optics and layout version. Qualitative and quantitative differences between the vertical and horizontal beam crossing schemes are highlighted. With measures in place to mitigate the effects of the interruption of the beam screen in the triplet interconnections and the Q4 aperture reduction, peak dose values in the superconducting coils remain below 30MGy in the triplet-D1 and below 12MGy in the matching section magnets for an integrated luminosity of 3000fb-1. Peak power density values are lower than 3mW/cm3 and 1mW/cm3 in the triplet and matching section respectively. Total heat loads in magnets, collimators, masks and absorbers were also estimated, along with dose and particle fluence maps relevant for Radiation to Electronics (R2E) aspects. The effect of a displacement of the interaction point is also addressed.
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TUPVA022	Requirements for Crab Cavity System Availability in HL-LHC	2097
	M. Valette, A. Apollonio, J.A. Uythoven, D. Wollmann CERN, Geneva, Switzerland
	Funding: Research supported by the HL-LHC project. Crab Cavities will be installed in the High Luminosity LHC in order to increase the effective peak luminosity through a partial compensation of the geometric factor. This will allow extending the levelling time resulting in an increased production of integrated luminosity. Based on the availability of the LHC during 2016 operation, the expected yearly-integrated luminosity of the future HL-LHC was estimated using a Monte Carlo model. Crab cavity faults were added to the observed failure distribu-tions and their impact on integrated luminosity produc-tion as a function of fault time and fault frequency was studied. This allows identifying a breakeven point in luminosity production and defining minimum system availability requirements for the crab cavities to reach the design goal of 250 fb-1 of integrated luminosity per year.
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TUPVA023	Effect of Quench Heater and CLIQ Firing on the Circulating HL-LHC Beam	2101
	M. Valette, L. Bortot, A.M. Fernandez Navarro, B. Lindstrom, R. Schmidt, A.P. Verweij, D. Wollmann CERN, Geneva, Switzerland
	Funding: Research supported by the HL-LHC project. A small vertical orbit oscillation of the LHC beam was observed following a quench of a main dipole magnet. This effect was thought to be caused by the current dis-charged in the quench heater (QH) strips of the superconducting magnet and confirmed in dedicated experiments with beam in the LHC. Quench heater connection schemes with the largest effect have been identified for the LHC and its future HiLumi upgrade (HL-LHC). Furthermore, the impact on the beam following discharges of the Coupling-Loss Induced Quench (CLIQ) system, a novel technology to protect high current superconducting magnets in case of a quench, was studied to evaluate the possible failure cases.
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TUPVA025	Observations of Beam Losses at the LHC During Reduction of Crossing Angle	2105
	B. Salvachua, X. Buffat, A.A. Gorzawski, T. Pieloni, S. Redaelli, C. Tambasco, J. Wenninger CERN, Geneva, Switzerland J. Barranco García, A.A. Gorzawski EPFL, Lausanne, Switzerland M.P. Crouch UMAN, Manchester, United Kingdom
	Several machine development studies have been performed in 2016 at the LHC in order to evaluate the effects of reducing the crossing angles in favor of defining the maximum achievable luminosity in the ATLAS and CMS experiments. At the end of the LHC proton-proton run at 6.5TeV the reduction of the crossing angle from 185urad to 140urad was operationally implemented. The observation of beam losses and lifetimes during this process are analysed and discussed.
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TUPVA026	Beam-Beam Studies for FCC-hh	2109
	J. Barranco García, T. Pieloni, C. Tambasco EPFL, Lausanne, Switzerland X. Buffat, S.V. Furuseth, C. Tambasco CERN, Geneva, Switzerland S.V. Furuseth NTNU, Trondheim, Norway
	Funding: This works was performed in the framework of the European Circular 'Energy Fr'ontier Collider Study, H2020 Framework Programme under grant agreement no. 654305. We acknowledge support from the Swiss State Secretariat for Education, Research and Innovation SERI. The Future Circular Collider hadron-hadron (FCC-hh) design study is currently exploring different IR design possibilities including round and flat optics or different crossing schemes. The present study intends to evaluate each scenario from the beam-beam effects point of view. In particular the single particle long term stability to maximize beam lifetimes and luminosity reach is used to quantify the differences. The impact of strong head on interactions on the beam quality and lifetime is addressed by means of GPU accelerated simulations code featuring a weak-strong 6-dimensional beam-beam interaction.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA026
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TUPVA027	Study of Beam-Beam Long Range Compensation with Octupoles	2113
	T. Pieloni, J. Barranco García, C. Tambasco EPFL, Lausanne, Switzerland X. Buffat, C. Tambasco CERN, Geneva, Switzerland
	Funding: The European Circular Energy-Frontier Collider Study (EuroCirCol), EU's Horizon 2020 grant No 654305. Long range beam-beam effects are responsible for particle losses and define fundamental operational parameters of colliders (i.e. crossing angles, intensities, emittances, β*). In this study we propose octuple magnets as a possible scheme to efficiently compensate long-range beam-beam interactions with a global correction scheme. The impact and improvements on the dynamic aperture of colliding beams together with estimates of the luminosity potentials are discussed for the HL-LHC upgrade and extrapolations made for the FCC project. Results are compared to other compensating schemes.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA027
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TUPVA029	Observations of Emittance Growth in the Presence of External Noise in the LHC	2117
	X. Buffat, C. Tambasco, D. Valuch CERN, Geneva, Switzerland J. Barranco García, T. Pieloni, C. Tambasco EPFL, Lausanne, Switzerland
	Dedicated experiments were perfomed in the LHC to study the impact of noise on colliding high brightness beams. The results are compared to theoretical models and multiparticle tracking simulations. The impacts on the LHC operation and the HL-LHC project are discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA029
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TUPVA030	Measurement of Beta-Beating Due to Strong Head-on Beam-Beam Interactions in the LHC	2121
	P. Gonçalves Jorge, J. Barranco García, T. Pieloni EPFL, Lausanne, Switzerland X. Buffat, F.S. Carlier, J.M. Coello de Portugal, E. Fol, L.E. Medina Medrano, R. Tomás, A. Wegscheider CERN, Geneva, Switzerland
	The LHC operation relies on a good knowledge of the optics, usually corrected in absence of beam-beam interactions. In a near future, both the LHC and the HL-LHC will need to cope with large head-on beam-beam parameters, the impact on the optics needs to be understood and, if necessary, corrected. The results of a dedicated experiment performed at injection energy are discussed in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA030
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TUPVA031	Impact of Incoherent Effects on the Landau Stability Diagram at the LHC	2125
	C. Tambasco, J. Barranco García, X. Buffat, T. Pieloni CERN, Geneva, Switzerland J. Barranco García, X. Buffat, T. Pieloni EPFL, Lausanne, Switzerland
	Instability thresholds are explored at the Large Hadron Collider (LHC) by means of the computation of the Landau Stability Diagrams (SD). In the presence of diffusive mechanisms, caused by resonance excitations or noise, the SD can be reduced due to the modification of the particle distribution inside the beam. This effect can lead to a possible lack of Landau damping of the coherent modes previously damped by lying within the unperturbed SD area. The limitations deriving from coherent instabilities in the LHC is crucial in view of future projects that aim to increase the performance of the LHC such as the High-Luminosity upgrade (HL-LHC). Simulation tools for the computation of the SD have been extended in order to take into account the incoherent effects from long tracking through the detailed model of the accelerator machine. The model includes among others beam-beam interactions and octupoles and the interplay between both is addressed. Finally the simulation results are compared to the Beam Transfer Function (BTF) measurements in the LHC.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA031
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TUPVA032	Beam-Gas Background Observations at LHC	2129
	S.M. Gibson Royal Holloway, University of London, Surrey, United Kingdom R. Alemany-Fernández, F. Alessio, G. Bregliozzi, H. Burkhardt, G. Corti, A. Di Mauro, M. Guthoff, A. Manousos, K.N. Sjobak, C. Yin Vallgren CERN, Geneva, Switzerland A. Alici Bologna University, Bologna, Italy S. D'Auria University of Glasgow, Glasgow, United Kingdom S.M. Gibson JAI, Egham, Surrey, United Kingdom D. Lazic BUphy, Boston, Massachusetts, USA
	Observations of beam-induced background at LHC during 2015 and 2016 are presented in this paper. The four LHC experiments use the non-colliding bunches present in the physics-filling pattern of the accelerator to trigger on beam-gas interactions. During luminosity production the LHC experiments record the beam-gas interactions using dedicated background monitors. These data are sent to the LHC control system and are used to monitor the background levels at the experiments during accelerator operation. This is a very important measurement, since poor beam-induced background conditions can seriously affect the performance of the detectors. A summary of the evolution of the background levels during 2015 and 2016 is given in these proceedings.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA032
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TUPVA034	SPS Studies in Preparation for the Crab Cavity Experiment	2133
	A. Alekou, A. Alekou, F. Antoniou, F. Antoniou, G. Arduini, G. Arduini, H. Bartosik, H. Bartosik, R. Calaga, R. Calaga, Y. Papaphilippou, Y. Papaphilippou, Y. Papaphilippou CERN, Geneva, Switzerland A. Alekou, R.B. Appleby, R.B. Appleby UMAN, Manchester, United Kingdom R.B. Appleby, C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom C.P. Welsch The University of Liverpool, Liverpool, United Kingdom
	A local Crab Cavity (CC) scheme will recover head-on collisions at the Interaction Points (IPs) of the High Luminosity LHC (HL-LHC), which aims to increase the LHC luminosity by a factor of 3-10. The first time that CC will ever be tested with proton beams will be in 2018 in the SPS machine. The available dedicated Machine Development (MD) time after the installation of the cavities will be limited and therefore good preparation is essential in order to ensure that the MDs are as efficient as possible. This paper presents the simulations and experimental studies performed in preparation for the future MDs and discusses the next steps.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA034
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TUPVA036	Cross-Talk Studies between FCC-hh Experimental Interaction Regions	2136
	J.L. Abelleira, A. Seryi JAI, Oxford, United Kingdom R.B. Appleby, H. Rafique UMAN, Manchester, United Kingdom M.I. Besana CERN, Geneva, Switzerland
	Funding: The European Circular Energy-Frontier Collider Study (EuroCirCol), EU's Horizon 2020 grant No 654305. Debris from 50 TeV proton-proton collisions at the main interaction point in the FCC-hh may contribute to the background in the subsequent detector. This cross-talk is of possible concern for the FCC-hh due to the high luminosity and energy of the collider. DPMJET-III is used as a collision debris generator in order to assess the muon cross-talk contribution. An analytical calculation of muon range in rock is performed. This is followed by a full Monte Carlo simulation using FLUKA, where the accelerator tunnel has been modelled. The muon cross talk between the adjacent interaction points is assessed and its implications for FCC-hh design are discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA036
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TUPVA037	FCC-hh Final-Focus for Flat-Beams: Parameters and Energy Deposition Studies	2139
	J.L. Abelleira, E. Cruz Alaniz, A. Seryi, L. van Riesen-Haupt JAI, Oxford, United Kingdom M.I. Besana CERN, Geneva, Switzerland
	Funding: The European Circular Energy-Frontier Collider Study (EuroCirCol), EU's Horizon 2020 grant No 654305. The international Future Circular Collider (FCC) study comprises the study of a new scientific structure in a tunnel of 100 km. This will allow the installation of two accelerators, a 45.6'175 GeV lepton collider and a 100-TeV hadron collider. An optimized design of a final-focus system for the hadron collider is presented here. The new design is more compact and enables unequal β* in both planes, whose choice is justified here. This is followed by energy deposition studies, where the total dose in the magnets as a consequence of the collision debris is evaluated.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA037
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TUPVA038	Non Linear Field Correction Effects on the Dynamic Aperture of the FCC-hh	2143
	E. Cruz Alaniz, A. Seryi JAI, Oxford, United Kingdom E.H. Maclean, R. Martin, R. Tomás CERN, Geneva, Switzerland
	Funding: European Union's Horizon 2020 research and innovation programme under grant No 654305. The Future Circular Collider (FCC) design study aims to develop the designs of possible circular colliders in the post LHC era. In particular the FCC-hh will aim to produce proton-proton collisions at a center of mass energy of 100 TeV. Given the large beta functions and integrated length of the quadrupoles of the final focus triplet the effect of systematic and random non linear errors in the magnets are expected to have a severe impact on the stability of the beam. Following the experience on the HL-LHC this work explores the implementation of non-linear correctors to minimize the resonance driving terms arising from the errors of the triplet. Dynamic aperture studies are then performed to study the impact of this correction.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA038
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TUPVA039	Effect of Alignment Errors and Orbit Correctors on the Interaction Region of the FCC-hh	2147
	E. Cruz Alaniz, J.L. Abelleira, A. Seryi, L. van Riesen-Haupt JAI, Oxford, United Kingdom J.L. Abelleira, L. van Riesen-Haupt University of Oxford, Oxford, United Kingdom
	Funding: European Union's Horizon 2020 research and innovation programme under grant No 654305. The Future Circular Collider (FCC) design study aims to develop the design of possible circular colliders in the LHC era. In particular the FCC-hh will aim to produce proton-proton collisions at a center of mass energy of 100 TeV. The interaction region has been designed to meet the requirements in terms of energy and luminosity. However, as it is the case in any real accelerator, misalignments in the magnets are likely to occur; the effect of these misalignments, if not properly compensated for, can jeopardize the performance of the machine. This study contemplates alignment and field errors in the interaction region in order to estimate the tolerance necessary to provide a good correction measured in terms of deviation of the orbit and strength of the correctors.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA039
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TUPVA040	Overview of Design Development of FCC-hh Experimental Interaction Regions	2151
	A. Seryi, J.L. Abelleira, E. Cruz Alaniz, L.J. Nevay, L. van Riesen-Haupt JAI, Oxford, United Kingdom R.B. Appleby, H. Rafique UMAN, Manchester, United Kingdom R.B. Appleby Cockcroft Institute, Warrington, Cheshire, United Kingdom J. Barranco García, T. Pieloni EPFL, Lausanne, Switzerland M. Benedikt, M.I. Besana, X. Buffat, H. Burkhardt, F. Cerutti, A. Langner, R. Martin, W. Riegler, D. Schulte, R. Tomás CERN, Geneva, Switzerland M. Boscolo, F. Collamati INFN/LNF, Frascati (Roma), Italy M. Hofer TU Vienna, Wien, Austria L.J. Nevay Royal Holloway, University of London, Surrey, United Kingdom L. van Riesen-Haupt University of Oxford, Oxford, United Kingdom
	The experimental interaction region is one of the key areas that define the performance of the Future Circular Collider. In this overview we will describe the status and the evolution of the design of EIR of FCC-hh, focusing on design of the optics, energy deposition in EIR elements, beam-beam effects and machine detector interface issues.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA040
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TUPVA041	Exploring the Triplet Parameter Space to Optimise the Final Focus of the FCC-hh	2155
	L. van Riesen-Haupt, J.L. Abelleira, E. Cruz Alaniz, A. Seryi JAI, Oxford, United Kingdom
	One of the main challenges when designing final focus systems of particle accelerators is maximising the beam stay clear in the strong quadrupole magnets of the inner triplet. Moreover it is desirable to keep the quadrupoles in the inner triplet as short as possible for space and costs reasons but also to reduce chromaticity and simplify corrections schemes. An algorithm that explores the triplet parameter space to optimise both these aspects was written. It uses thin lenses as a first approximation and MADX for more precise calculations. In cooperation with radiation studies, this algorithm was then applied to design an alternative triplet for the final focus of the Future Circular Collider.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA041
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TUPVA042	K-Modulation Developments via Simultaneous Beam Based Alignment in the LHC	2159
	L. van Riesen-Haupt, A. Seryi JAI, Oxford, United Kingdom J.M. Coello de Portugal, E. Fol, R. Tomás, R. Tomás CERN, Geneva, Switzerland
	Funding: EuroCirCol A parasitic effect of k-modulation is that if the modulated quadrupole has an offset the modulation results in a dipole like kick forcing the beam on a new orbit. This paper presents a new method using the orthonormality of singular value decomposition that uses this new orbit to estimate the offset. This could be used to measure misalignments or crossing angles but could also help improve k-modulation \beta measurements by predicting the parasitic tune change caused by the new orbit not passing through the centre of the sextupoles.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA042
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TUPVA043	A Code for Optimising Triplet Layout	2163
	L. van Riesen-Haupt, J.L. Abelleira, E. Cruz Alaniz, A. Seryi JAI, Oxford, United Kingdom
	Funding: EuroCirCol One of the main challenges when designing final focus systems of particle accelerators is maximising the beam stay clear in the strong quadrupole magnets of the inner triplet. Moreover it is desirable to keep the quadrupoles in the inner triplet as short as possible for space and costs reasons but also to reduce chromaticity and simplify corrections schemes. An algorithm that explores the triplet parameter space to optimise both these aspects was written. It uses thin lenses as a first approximation for a broad parameter scan and MADX for more precise calculations. The thin lens algorithm is significantly faster than a full scan using MADX and relatively precise at indicating the approximate area where the optimum solution lies.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA043
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TUPVA044	Modelling and Measurements of Bunch Profiles at the LHC	2167
	S. Papadopoulou, F. Antoniou, T. Argyropoulos, M. Hostettler, Y. Papaphilippou CERN, Geneva, Switzerland M. Fitterer Fermilab, Batavia, Illinois, USA
	The bunch profiles in the LHC are often observed to be non-Gaussian, both at Flat Bottom (FB) and Flat Top (FT) energies. Especially at FT, an evolution of the tail population in time is observed. In this respect, the Monte-Carlo Software for IBS and Radiation effects (SIRE) is used to track different types of beam distributions. The impact of the distribution shape on the evolution of bunch characteristics is studied. The results are compared with observations from the LHC Run 2 data.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA044
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TUPVA045	Compensation of Head-on Beam-Beam Induced Resonance Driving Terms and Tune Spread in the Relativistic Heavy Ion Collider	2171
	W. Fischer, X. Gu, C. Liu, Y. Luo, A. Marusic, R.J. Michnoff, T.A. Miller, M.G. Minty, C. Montag, A.I. Pikin, G. Robert-Demolaize, V. Schoefer, P. Thieberger BNL, Upton, Long Island, New York, USA S.M. White ESRF, Grenoble, France
	Funding: Work supported by U.S. DOE under contract No DE-AC02-98CH10886 with the U.S. Department of Energy. A head-on beam-beam compensation scheme was implemented for operation in the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory. The compensation consists of a lattice for the minimization of beam-beam driven resonance driving terms, and electron lenses for the reduction of the beam-beam induced tune spread. We describe the implementations of the lattice and electron lenses, and report on measurements of lattice properties and the effect of the electron lenses on the hadron beam.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA045
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TUPVA046	Beam Energy Scan With Asymmetric Collision at RHIC	2175
	C. Liu, J.G. Alessi, E.N. Beebe, M. Blaskiewicz, J.M. Brennan, K.A. Brown, D. Bruno, J.J. Butler, R. Connolly, T. D'Ottavio, K.A. Drees, W. Fischer, C.J. Gardner, D.M. Gassner, X. Gu, Y. Hao, M. Harvey, T. Hayes, H. Huang, R.L. Hulsart, P.F. Ingrassia, J.P. Jamilkowski, J.S. Laster, V. Litvinenko, Y. Luo, M. Mapes, G.J. Marr, A. Marusic, G.T. McIntyre, K. Mernick, R.J. Michnoff, M.G. Minty, C. Montag, J. Morris, C. Naylor, S. Nemesure, I. Pinayev, V.H. Ranjbar, D. Raparia, G. Robert-Demolaize, T. Roser, P. Sampson, J. Sandberg, V. Schoefer, F. Severino, T.C. Shrey, K.S. Smith, S. Tepikian, R. Than, P. Thieberger, J.E. Tuozzolo, G. Wang, Q. Wu, A. Zaltsman, K. Zeno, S.Y. Zhang, W. Zhang BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. A beam energy scan of deuteron-gold collision, with center-of-mass energy at 19.6, 39, 62.4 and 200.7 GeV/n, was performed at the Relativistic Heavy Ion Collider in 2016 to study the threshold for quark-gluon plasma (QGP) production. The lattice, RF, stochastic cooling and other subsystems were in different configurations for the various energies. The operational challenges changed with every new energy. The operational experience at each energy, the operation performance, highlights and lessons of the beam energy scan are reviewed in this report.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA046
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TUPVA047	IBS Simulation with Different RF Configurations in RHIC	2178
	C. Liu, A.V. Fedotov, M.G. Minty, V. Ptitsyn BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. This report focuses on three dimensional emittance growth of polarized proton beam due to Intra-Beam Scattering (IBS) at RHIC. Simulations are presented which give guidance on the configuration of the RF systems to mitigate IBS-induced emittance growth. In addition, simulated growth rates are compared with measured emittance evolution at injection, which shows better agreement in longitudinal than transverse dimension. The results in this report will help us better understand the emittance evolution for current RHIC operations and for future operations (eRHIC).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA047
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TUPVA048	Calculation of Particle Loss Maps for 2016 RHIC Gold-Gold Run	2181
	Y. Luo, K.A. Drees, W. Fischer, X. Gu, A. Marusic, G. Robert-Demolaize, V. Schoefer BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. In the 2016 RHIC 100~GeV gold-gold (Au-Au) run, 20~mm orbit bumps were installed in the arcs to protect the experimental detectors from abort kicker prefiring. Chronic particle losses were observed in the arcs with these orbit bumps. Those particle losses are mainly from the 78+Au197 and 79+Au196 particles generated from bound-free pair production (BFPP) and electromagnetic dissociation (EMD) associated with the Au-Au collision at the IPs. In this article, we present simulated particle losses of 78+Au197 and 79+Au196 and calculate the particle loss distribution in the ring. The calculated particle loss maps are compared with operational observations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA048
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TUPVA049	Re-Visiting RHIC Snakes and Spin Orbit	2184
	F. Méot, R.C. Gupta, H. Huang, A. Marusic, V.H. Ranjbar, G. Robert-Demolaize BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. Recent analyses of RHIC run12 to run15 proton-carbon polarimeter measurements have shown significant tilt of the polarization vector from vertical, at high energy essentially. This is confirmed by extensive measurements performed in the present Run 17. Possible origins of such large tilt may reside in snake spin rotation angle or orbit defects, to mention just two. Dedicated simulations have been undertaken to investigate possible causes, they are presented and discussed, they include the computation and use of 3-D field maps of RHIC siberian snakes.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA049
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TUPVA050	RHIC Polarized Proton Operation for 2017	2188
	V.H. Ranjbar, P. Adams, Z. Altinbas, E.C. Aschenauer, G. Atoian, E.N. Beebe, S. Binello, I. Blackler, M. Blaskiewicz, J.M. Brennan, K.A. Brown, D. Bruno, M.R. Costanzo, T. D'Ottavio, K.A. Drees, P.S. Dyer, A.V. Fedotov, W. Fischer, C.J. Gardner, D.M. Gassner, X. Gu, C.E. Harper, M. Harvey, T. Hayes, J. Hock, H. Huang, R.L. Hulsart, J.P. Jamilkowski, T. Kanesue, N.A. Kling, J.S. Laster, C. Liu, Y. Luo, D. Maffei, M. Mapes, G.J. Marr, A. Marusic, F. Méot, K. Mernick, R.J. Michnoff, T.A. Miller, M.G. Minty, C. Montag, J. Morris, G. Narayan, C. Naylor, S. Nemesure, P. Oddo, M. Okamura, S. Perez, A.I. Pikin, A. Poblaguev, S. Polizzo, V. Ptitsyn, D. Raparia, G. Robert-Demolaize, T. Roser, J. Sandberg, W.B. Schmidke, V. Schoefer, F. Severino, T.C. Shrey, K.S. Smith, Z. Sorrell, D. Steski, S. Tepikian, R. Than, P. Thieberger, J.E. Tuozzolo, G. Wang, K. Yip, A. Zaltsman, A. Zelenski, K. Zeno, W. Zhang, B. van Kuik BNL, Upton, Long Island, New York, USA
	Funding: Work supported by the US Department of Energy under contract number DE-SC0012704 The 2017 operation of the Relativistic Heavy Ion Collider (RHIC) involved the running of only a single experiment at STAR with PHENIX offline in the process of the upgrade to sPHENIX. For this run there were several notable changes to machine operations. These included, transverse polarization, luminosity leveling, a new approach to machine protection and the development of new store and ramped lattices. The new 255 GeV store lattice was designed to both accommodate the necessary phase advance between the e-lens and IP8 for testing and to maximize dynamic aperture. The new lattices on the ramp were designed to maximize polarization transmission during the three strong intrinsic spin resonances crossings. Finally we are also commissioning new 9 MHz RF cavities during this run.
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TUPVA115	Progress with Long-Range Beam-Beam Compensation Studies for High Luminosity LHC	2358
	A. Rossi, O. Aberle, J. Albertone, A. Bertarelli, C.B. Boccard, F. Carra, G. Cattenoz, Y. Delaup, S.D. Fartoukh, G. Gobbi, J. Lendaro, Y. Papaphilippou, D. Perini, S. Redaelli, H. Schmickler, C. Zanoni CERN, Geneva, Switzerland A.M. Barnyakov, A.E. Levichev, D.A. Nikiforov BINP SB RAS, Novosibirsk, Russia M. Fitterer, A.S. Patapenka, G. Stancari, A. Valishev Fermilab, Batavia, Illinois, USA
	Long-range beam-beam (LRBB) interactions can be a source of emittance growth and beam losses in the LHC during physics and will become even more relevant with the smaller '* and higher bunch intensities foreseen for the High Luminosity LHC upgrade (HL-LHC), in particular if operated without crab cavities. Both beam losses and emittance growth could be mitigated by compensat-ing the non-linear LRBB kick with a correctly placed current carrying wire. Such a compensation scheme is currently being studied in the LHC through a demonstration test using current-bearing wires embedded into col-limator jaws, installed either side of the high luminosity interaction regions. For HL-LHC two options are considered, a current-bearing wire as for the demonstrator, or electron lenses, as the ideal distance between the particle beam and compensating current may be too small to allow the use of solid materials. This paper reports on the ongoing activities for both options, covering the progress of the wire-in-jaw collimators, the foreseen LRBB experiments at the LHC, and first considerations for the design of the electron lenses to ultimately replace material wires for HL-LHC.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA115
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TUPVA127	Optimisation of the Design of the Future Circular Collider from a Civil Engineering Perspective	2392
	J.L. Stanyard, V. Mertens, J.A. Osborne CERN, Geneva, Switzerland Y. Loo, C. Sturzaker, M. Sykes ARUP, London, United Kingdom
	This paper describes the role of civil engineering in the optimisation of the design of CERN's Future Circular Collider (FCC). The civil engineering team at CERN have employed a bespoke, interactive, geological tool to consider the suitability of multiple layout options for the FCC, situated in the Geneva Basin, in particular quasi-circular options with circumferences in the order of 100 km. The tool has been used to provide feedback on potential lattice designs that are assessed based on criteria such as geological risk, shaft depth and the environmental sensitivities of access and experimental sites. This paper presents the process and some results of the impact of civil engineering on the design of the FCC, in particular on the layout, location, and structural requirements, and also how the optimised design has been used as the basis for a cost and schedule study.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA127
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