IPAC2018 - List of Authors (Tomas, R.)

Paper	Title	Page
MOPMF032	Nonlinear Correction Strategies for the LHC Using Resonance Driving Terms	161
	F.S. Carlier, E.H. Maclean, T. Persson, R. Tomás CERN, Geneva, Switzerland
	The correction of nonlinearities in future colliders is critical to reach operational conditions and pose a significant challenge for commissioning schemes. Several approaches have been succesfully used in the LHC to correct sextupolar and octupolar sources in the LHC insertion regions. Measurements of resonance driving terms at top energy in the LHC have improved and now offer a new observable to calculate and validate nonlinear corrections. This paper reports on measurements of resonance driving terms in the LHC and the relevant strategies used for nonlinear corrections.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF032
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MOPMF033	Probing the Forced Dynamic Aperture in the LHC at Top Energy Using AC Dipoles	165
SUSPF001	use link to see paper's listing under its alternate paper code
	F.S. Carlier, M. Giovannozzi, E.H. Maclean, T. Persson, R. Tomás CERN, Geneva, Switzerland
	Measurements of the dynamic aperture in colliders are a common method to ensure machine performance and offer an insight in the nonlinear content of the machine. Such direct measurements are very challenging for the LHC and High Luminosity LHC. Forced dynamic aperture has been demonstrated for the first time in the LHC at injection energy as a potential new observable to safely probe the nonlinear content of the machine. This paper presents the first measurements of forced dynamic aperture at top energy and discusses the proposed measurement schemes and challenges.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF033
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MOPMF043	Tuning of CLIC-Final Focus System 3 TeV Baseline Design Under Static and Dynamic Imperfections	196
	E. Marín, A. Latina, J. Pfingstner, D. Schulte, R. Tomás CERN, Geneva, Switzerland J. Pfingstner University of Oslo, Oslo, Norway
	In this paper we present the tuning study of the Compact Linear Collider - Final Focus System (CLIC-FFS) 3~TeV baseline design under static and dynamic imperfections for the first time. The motion of the FFS magnets due to ground motion and the impact of active and passive mechanisms envisaged to stabilize both e^- and e⁺ systems are described. It is found that the Pre-isolator required for stabilization of the Final Doublet drives the performance of the collider at the final stages of the tuning process. The obtained tuning performance depending on the stabilization techniques are discussed in detail.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF043
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MOPMF047	Transverse Coupling Measurements With High Intensity Beams Using Driven Oscillations	208
	T. Persson, G. Baud, X. Buffat, J.M. Coello de Portugal, E. Fol, K. Fuchsberger, M. Gabriel, M. Gąsior, M. Giovannozzi, G.H. Hemelsoet, M. Hostettler, M. Hruska, D. Jacquet, E.H. Maclean, L. Malina, J. Olexa, P.K. Skowroński, M. Solfaroli Camillocci, M.E. Söderén, R. Tomás, D. Valuch, A. Wegscheider, J. Wenninger CERN, Geneva, Switzerland
	Transverse coupling has been linked to instabilities and reduction in dynamic aperture and is hence a crucial parameter to control in the LHC. In this article we describe the development to use driven oscillations to measure the transverse coupling with high intensity beams. The method relies on the use of the transverse damper to drive an oscillation in a similar way as with an AC-dipole. The calculation of the coupling is based on the turn-by-turn data from all available BPMs gated for the excited bunch.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF047
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MOPMF048	Aperture Measurements with AC Dipole at the Large Hadron Collider	212
	N. Fuster-Martínez, R. Bruce, J. Dilly, E.H. Maclean, T. Persson, S. Redaelli, R. Tomás CERN, Geneva, Switzerland L.J. Nevay Royal Holloway, University of London, Surrey, United Kingdom
	Global aperture measurements are crucial for a safe operation and to push the performance of the LHC, in particular, the knowledge of aperture at top energy allows pushing the optics to reduce the colliding beam sizes. The standard method used in the LHC commissioning requires using several bunches for one measurement and makes bunches un-usable for other activities. This paper presents first global aperture measurements performed at injection with a new method using the AC dipole. This method consists in exciting large coherent oscillations of the beam without spoiling its emittance. A gentle control of the oscillation amplitude enables re-using the beams for several measurements. These measurements are compared with aperture measurements performed using the standard method and possible benefits, for example for optics measurements, at top energy with squeezed optics, are elaborated.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF048
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MOPMF064	High-Energy LHC Design	269
	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, R. Kersevan, V. Mertens, 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, E. Cruz Alaniz, P. Martinez Mirave, 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
	In the frame of the FCC study we are designing a 27 TeV hadron collider in the LHC tunnel, called the High Energy LHC (HE-LHC).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF064
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MOPMF067	Optimized Arc Optics for the HE-LHC	277
	Y.M. Nosochkov, Y. Cai SLAC, Menlo Park, California, USA M.P. Crouch, M. Giovannozzi, M. Hofer, J. Keintzel, T. Risselada, E. Todesco, R. Tomás, F. Zimmermann CERN, Geneva, Switzerland D. Zhou KEK, Ibaraki, Japan L. van Riesen-Haupt JAI, Oxford, United Kingdom
	Funding: Work supported by the European Commission under Capacities 7th Framework Programme project EuCARD-2, grant agreement 312453, and the HORIZON 2020 project EuroCirCol, grant agreement 654305. The High Energy LHC (HE-LHC) proton-proton collider is a proposed replacement of the LHC in the existing 27-km tunnel, with the goal of reaching the centre-of-mass beam energy of 27 TeV. The required higher dipole field can be realized by using 16-T dipoles being developed for the FCC-hh design. A major concern is the dynamic aperture at injection energy due to degraded field quality of the new dipole based on Nb3Sn superconductor, the potentially large energy swing between injection and collision, and the slightly reduced magnet aperture. Another issue is the field in quadrupoles and sextupoles at top energy, for which it may be cost-effective, wherever possible, to stay with Nb-Ti technology. In this study, we explore design options differed by arc lattice, for three choices of injection energy, with the goal of attaining acceptable magnet field and maximum injection dynamic aperture with dipole non-linear field errors.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF067
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MOPMK002	Integrated Full HE-LHC Optics and Its Performance	348
	M. Hofer TU Vienna, Wien, Austria M.P. Crouch, J. Keintzel, T. Risselada, R. Tomás, F. Zimmermann CERN, Geneva, Switzerland Y.M. Nosochkov SLAC, Menlo Park, California, USA D. Zhou KEK, Ibaraki, Japan L. van Riesen-Haupt JAI, Oxford, United Kingdom
	One possible future hadron collider design investigated in the framework of the Future Circular Collider (FCC) study is the High-Energy LHC (HE-LHC). Using the 16 T dipoles developed for the FCC-hh the center of mass energy of the LHC is set to increase to 27 TeV. To achieve this set energy goal, a new optics design is required, taking into account the constraint from the LHC tunnel geometry. In this paper, two different lattices for the HE-LHC are presented. Initial considerations take into account the physical aperture at the proposed injection energy as well as the energy reach of these lattices. The dynamic aperture at the injection energies is determined using latest evaluations of the field quality of the main dipoles.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMK002
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MOPML009	New High Luminosity LHC Baseline and Performance at Ultimate Energy	408
	L.E. Medina Medrano Universidad de Guanajuato, División de Ciencias e Ingenierías, León, Mexico A. Apollonio, G. Arduini, O.S. Brüning, M. Giovannozzi, L.E. Medina Medrano, S. Papadopoulou, Y. Papaphilippou, S. Redaelli, R. Tomás CERN, Geneva, Switzerland
	Funding: Research supported by the HL-LHC project and the Beam project (CONACYT, Mexico). The LHC machine is envisioned to operate eventually at an ultimate beam energy of 7.5 TeV at the end of LHC Run 4, i.e. after commissioning of the HL-LHC systems, a stage falling into the High Luminosity LHC (HL-LHC) era. In this paper we review the latest baseline parameters and performance, and study the potential reach of the HL-LHC with pushed optics at the ultimate beam energy. Results in terms of integrated luminosity and effective pile-up density of both the nominal (5.0×10³⁴ cm^-2 s⁻¹) and ultimate (7.5×10³⁴ cm^-2 s⁻¹) levelling operations are discussed
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML009
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WEPAF062	Machine Learning Methods for Optics Measurements and Corrections at LHC	1967
	E. Fol, F.S. Carlier, J.M. Coello de Portugal, A. Garcia-Tabares, R. Tomás CERN, Geneva, Switzerland
	The application of machine learning methods and concepts of artificial intelligence can be found in various industry and scientific branches. In Accelerator Physics the machine learning approach has not found a wide application yet. This paper is devoted to evaluation of machine learning methods aiming to improve the optics measurements and corrections at LHC. The main subjects of the study are devoted to recognition and analysis of faulty beam position monitors and prediction of quadrupole errors using clustering algorithms, decision trees and artificial neural networks. The results presented in this paper clearly show the suitability of machine learning methods for the optics control at LHC and the potential for further investigation on appropriate approaches.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF062
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THPAF045	Performance Optimisation of Turn-by-Turn Beam Position Monitor Data Harmonic Analysis	3064
	L. Malina, J.M. Coello de Portugal, J. Dilly, P.K. Skowroński, R. Tomás, M.S. Toplis CERN, Geneva, Switzerland J.M. Coello de Portugal UPC, Barcelona, Spain
	Nowadays, turn-by-turn beam position monitor data is increasingly utilized in many accelerators, as it allows for fast and simultaneous measurement of various optics parameters. The accurate harmonic analysis of turn-by-turn data costs beam time when needed online. Generally, the electronic noise is avoided by cleaning of the data based on singular value decomposition. In this paper, we exploit the cleaning procedure to compress the data for the harmonic analysis. This way the harmonic analysis is sped up by an order of magnitude. The impact on measurement accuracy is discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF045
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THPAK135	Assessment of Linear and Non-Linear Optics Errors due to Beam-Beam with Multipoles for the High Luminosity LHC	3557
	L.E. Medina Medrano Universidad de Guanajuato, División de Ciencias e Ingenierías, León, Mexico J. Barranco García, T. Pieloni EPFL, Lausanne, Switzerland X. Buffat, L.E. Medina Medrano, R. Tomás CERN, Geneva, Switzerland
	Funding: HL-LHC project, European Circular Energy-Frontier Collider Study, H2020 programme (Grant 654305), Swiss State Secretariat for Education, Research and Innovation (SERI), Beam project (CONACYT, Mexico). Study of the head-on and long-range beam-beam effects in the High Luminosity LHC (HL-LHC) is of interest to evaluate their potential impact on performance (in the form of luminosity imbalance) and machine operation (collimator system), and, depending on their magnitude, correction schemes might be necessary to minimize them. In this work, both the β-beating at zero amplitude and its amplitude-dependence are computed for the current HL-LHC baseline optics and parameters, as well as the amplitude detuning, at the main interaction points and collimators. Correction of the β-beating, tune shift and footprint for the HL-LHC, as originally proposed for the LHC, via compensation of the multipolar terms of the beam-beam force with corrector magnets, is also discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK135
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THPAK145	Methods to Increase the Dynamic Aperture of the FCC-hh Lattice	3593
	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 R. Martin, R. Tomás CERN, Geneva, Switzerland
	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. Initial tracking studies for the FCC-hh lattice at collision energy including field errors on the final focus triplet showed a very low dynamic aperture, most likely affected by the large beta functions and integrated length of the quadrupoles. Using non-linear correctors, the dynamic aperture was increased to acceptable levels; however, the difficulty to have an accurate magnetic model of the magnets required for this correction motivates the development of alternative methods. This work explores the possibility to increase the dynamic aperture by optimizing the phase advance between the main interaction regions. The description of this method along with its impact on the dynamic aperture will be given on this paper.
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Paper

Title

Page

Nonlinear Correction Strategies for the LHC Using Resonance Driving Terms

161

F.S. Carlier, E.H. Maclean, T. Persson, R. Tomás
CERN, Geneva, Switzerland

The correction of nonlinearities in future colliders is critical to reach operational conditions and pose a significant challenge for commissioning schemes. Several approaches have been succesfully used in the LHC to correct sextupolar and octupolar sources in the LHC insertion regions. Measurements of resonance driving terms at top energy in the LHC have improved and now offer a new observable to calculate and validate nonlinear corrections. This paper reports on measurements of resonance driving terms in the LHC and the relevant strategies used for nonlinear corrections.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF032

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MOPMF033

Probing the Forced Dynamic Aperture in the LHC at Top Energy Using AC Dipoles

165

SUSPF001

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

F.S. Carlier, M. Giovannozzi, E.H. Maclean, T. Persson, R. Tomás
CERN, Geneva, Switzerland

Measurements of the dynamic aperture in colliders are a common method to ensure machine performance and offer an insight in the nonlinear content of the machine. Such direct measurements are very challenging for the LHC and High Luminosity LHC. Forced dynamic aperture has been demonstrated for the first time in the LHC at injection energy as a potential new observable to safely probe the nonlinear content of the machine. This paper presents the first measurements of forced dynamic aperture at top energy and discusses the proposed measurement schemes and challenges.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF033

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MOPMF043

Tuning of CLIC-Final Focus System 3 TeV Baseline Design Under Static and Dynamic Imperfections

196

E. Marín, A. Latina, J. Pfingstner, D. Schulte, R. Tomás
CERN, Geneva, Switzerland
J. Pfingstner
University of Oslo, Oslo, Norway

In this paper we present the tuning study of the Compact Linear Collider - Final Focus System (CLIC-FFS) 3~TeV baseline design under static and dynamic imperfections for the first time. The motion of the FFS magnets due to ground motion and the impact of active and passive mechanisms envisaged to stabilize both e^- and e⁺ systems are described. It is found that the Pre-isolator required for stabilization of the Final Doublet drives the performance of the collider at the final stages of the tuning process. The obtained tuning performance depending on the stabilization techniques are discussed in detail.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF043

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MOPMF047

Transverse Coupling Measurements With High Intensity Beams Using Driven Oscillations

208

T. Persson, G. Baud, X. Buffat, J.M. Coello de Portugal, E. Fol, K. Fuchsberger, M. Gabriel, M. Gąsior, M. Giovannozzi, G.H. Hemelsoet, M. Hostettler, M. Hruska, D. Jacquet, E.H. Maclean, L. Malina, J. Olexa, P.K. Skowroński, M. Solfaroli Camillocci, M.E. Söderén, R. Tomás, D. Valuch, A. Wegscheider, J. Wenninger
CERN, Geneva, Switzerland

Transverse coupling has been linked to instabilities and reduction in dynamic aperture and is hence a crucial parameter to control in the LHC. In this article we describe the development to use driven oscillations to measure the transverse coupling with high intensity beams. The method relies on the use of the transverse damper to drive an oscillation in a similar way as with an AC-dipole. The calculation of the coupling is based on the turn-by-turn data from all available BPMs gated for the excited bunch.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF047

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MOPMF048

Aperture Measurements with AC Dipole at the Large Hadron Collider

212

N. Fuster-Martínez, R. Bruce, J. Dilly, E.H. Maclean, T. Persson, S. Redaelli, R. Tomás
CERN, Geneva, Switzerland
L.J. Nevay
Royal Holloway, University of London, Surrey, United Kingdom

Global aperture measurements are crucial for a safe operation and to push the performance of the LHC, in particular, the knowledge of aperture at top energy allows pushing the optics to reduce the colliding beam sizes. The standard method used in the LHC commissioning requires using several bunches for one measurement and makes bunches un-usable for other activities. This paper presents first global aperture measurements performed at injection with a new method using the AC dipole. This method consists in exciting large coherent oscillations of the beam without spoiling its emittance. A gentle control of the oscillation amplitude enables re-using the beams for several measurements. These measurements are compared with aperture measurements performed using the standard method and possible benefits, for example for optics measurements, at top energy with squeezed optics, are elaborated.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF048

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MOPMF064

High-Energy LHC Design

269

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, R. Kersevan, V. Mertens, 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, E. Cruz Alaniz, P. Martinez Mirave, 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

In the frame of the FCC study we are designing a 27 TeV hadron collider in the LHC tunnel, called the High Energy LHC (HE-LHC).

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF064

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MOPMF067

Optimized Arc Optics for the HE-LHC

277

Y.M. Nosochkov, Y. Cai
SLAC, Menlo Park, California, USA
M.P. Crouch, M. Giovannozzi, M. Hofer, J. Keintzel, T. Risselada, E. Todesco, R. Tomás, F. Zimmermann
CERN, Geneva, Switzerland
D. Zhou
KEK, Ibaraki, Japan
L. van Riesen-Haupt
JAI, Oxford, United Kingdom

Funding: Work supported by the European Commission under Capacities 7th Framework Programme project EuCARD-2, grant agreement 312453, and the HORIZON 2020 project EuroCirCol, grant agreement 654305.
The High Energy LHC (HE-LHC) proton-proton collider is a proposed replacement of the LHC in the existing 27-km tunnel, with the goal of reaching the centre-of-mass beam energy of 27 TeV. The required higher dipole field can be realized by using 16-T dipoles being developed for the FCC-hh design. A major concern is the dynamic aperture at injection energy due to degraded field quality of the new dipole based on Nb3Sn superconductor, the potentially large energy swing between injection and collision, and the slightly reduced magnet aperture. Another issue is the field in quadrupoles and sextupoles at top energy, for which it may be cost-effective, wherever possible, to stay with Nb-Ti technology. In this study, we explore design options differed by arc lattice, for three choices of injection energy, with the goal of attaining acceptable magnet field and maximum injection dynamic aperture with dipole non-linear field errors.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF067

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MOPMK002

Integrated Full HE-LHC Optics and Its Performance

348

M. Hofer
TU Vienna, Wien, Austria
M.P. Crouch, J. Keintzel, T. Risselada, R. Tomás, F. Zimmermann
CERN, Geneva, Switzerland
Y.M. Nosochkov
SLAC, Menlo Park, California, USA
D. Zhou
KEK, Ibaraki, Japan
L. van Riesen-Haupt
JAI, Oxford, United Kingdom

One possible future hadron collider design investigated in the framework of the Future Circular Collider (FCC) study is the High-Energy LHC (HE-LHC). Using the 16 T dipoles developed for the FCC-hh the center of mass energy of the LHC is set to increase to 27 TeV. To achieve this set energy goal, a new optics design is required, taking into account the constraint from the LHC tunnel geometry. In this paper, two different lattices for the HE-LHC are presented. Initial considerations take into account the physical aperture at the proposed injection energy as well as the energy reach of these lattices. The dynamic aperture at the injection energies is determined using latest evaluations of the field quality of the main dipoles.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMK002

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MOPML009

New High Luminosity LHC Baseline and Performance at Ultimate Energy

408

L.E. Medina Medrano
Universidad de Guanajuato, División de Ciencias e Ingenierías, León, Mexico
A. Apollonio, G. Arduini, O.S. Brüning, M. Giovannozzi, L.E. Medina Medrano, S. Papadopoulou, Y. Papaphilippou, S. Redaelli, R. Tomás
CERN, Geneva, Switzerland

Funding: Research supported by the HL-LHC project and the Beam project (CONACYT, Mexico).
The LHC machine is envisioned to operate eventually at an ultimate beam energy of 7.5 TeV at the end of LHC Run 4, i.e. after commissioning of the HL-LHC systems, a stage falling into the High Luminosity LHC (HL-LHC) era. In this paper we review the latest baseline parameters and performance, and study the potential reach of the HL-LHC with pushed optics at the ultimate beam energy. Results in terms of integrated luminosity and effective pile-up density of both the nominal (5.0×10³⁴ cm^-2 s⁻¹) and ultimate (7.5×10³⁴ cm^-2 s⁻¹) levelling operations are discussed

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML009

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WEPAF062

Machine Learning Methods for Optics Measurements and Corrections at LHC

1967

E. Fol, F.S. Carlier, J.M. Coello de Portugal, A. Garcia-Tabares, R. Tomás
CERN, Geneva, Switzerland

The application of machine learning methods and concepts of artificial intelligence can be found in various industry and scientific branches. In Accelerator Physics the machine learning approach has not found a wide application yet. This paper is devoted to evaluation of machine learning methods aiming to improve the optics measurements and corrections at LHC. The main subjects of the study are devoted to recognition and analysis of faulty beam position monitors and prediction of quadrupole errors using clustering algorithms, decision trees and artificial neural networks. The results presented in this paper clearly show the suitability of machine learning methods for the optics control at LHC and the potential for further investigation on appropriate approaches.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF062

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THPAF045

Performance Optimisation of Turn-by-Turn Beam Position Monitor Data Harmonic Analysis

3064

L. Malina, J.M. Coello de Portugal, J. Dilly, P.K. Skowroński, R. Tomás, M.S. Toplis
CERN, Geneva, Switzerland
J.M. Coello de Portugal
UPC, Barcelona, Spain

Nowadays, turn-by-turn beam position monitor data is increasingly utilized in many accelerators, as it allows for fast and simultaneous measurement of various optics parameters. The accurate harmonic analysis of turn-by-turn data costs beam time when needed online. Generally, the electronic noise is avoided by cleaning of the data based on singular value decomposition. In this paper, we exploit the cleaning procedure to compress the data for the harmonic analysis. This way the harmonic analysis is sped up by an order of magnitude. The impact on measurement accuracy is discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF045

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THPAK135

Assessment of Linear and Non-Linear Optics Errors due to Beam-Beam with Multipoles for the High Luminosity LHC

3557

L.E. Medina Medrano
Universidad de Guanajuato, División de Ciencias e Ingenierías, León, Mexico
J. Barranco García, T. Pieloni
EPFL, Lausanne, Switzerland
X. Buffat, L.E. Medina Medrano, R. Tomás
CERN, Geneva, Switzerland

Funding: HL-LHC project, European Circular Energy-Frontier Collider Study, H2020 programme (Grant 654305), Swiss State Secretariat for Education, Research and Innovation (SERI), Beam project (CONACYT, Mexico).
Study of the head-on and long-range beam-beam effects in the High Luminosity LHC (HL-LHC) is of interest to evaluate their potential impact on performance (in the form of luminosity imbalance) and machine operation (collimator system), and, depending on their magnitude, correction schemes might be necessary to minimize them. In this work, both the β-beating at zero amplitude and its amplitude-dependence are computed for the current HL-LHC baseline optics and parameters, as well as the amplitude detuning, at the main interaction points and collimators. Correction of the β-beating, tune shift and footprint for the HL-LHC, as originally proposed for the LHC, via compensation of the multipolar terms of the beam-beam force with corrector magnets, is also discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK135

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THPAK145

Methods to Increase the Dynamic Aperture of the FCC-hh Lattice

3593

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
R. Martin, R. Tomás
CERN, Geneva, Switzerland

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. Initial tracking studies for the FCC-hh lattice at collision energy including field errors on the final focus triplet showed a very low dynamic aperture, most likely affected by the large beta functions and integrated length of the quadrupoles. Using non-linear correctors, the dynamic aperture was increased to acceptable levels; however, the difficulty to have an accurate magnetic model of the magnets required for this correction motivates the development of alternative methods. This work explores the possibility to increase the dynamic aperture by optimizing the phase advance between the main interaction regions. The description of this method along with its impact on the dynamic aperture will be given on this paper.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK145

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