IPAC2017 - List of Authors (Tomas, R.)

Paper	Title	Page
MOPAB040	Linear and Nonlinear Optics Measurements With Multiturn Data at PETRA III	170
	I.V. Agapov, M. Bieler, H. Ehrlichmann, J. Keil, J. Klute, G. Kube, G.K. Sahoo, F. Schmidt-Föhre, R. Wanzenberg DESY, Hamburg, Germany R. Tomás, A. Wegscheider CERN, Geneva, Switzerland
	At Petra III measuring multiturn beam response to pulsed and continuous excitations allows linear and nonlinear (e.g. frequency maps) optics parameter determination. We describe the measurement setup, approaches to optics parameter determination, and the measurement results for Petra III.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB040
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MOPAB130	Cross-Calibration of the LHC Transverse Beam-Profile Monitors	437
	R. Alemany-Fernández, F. Alessio, A. Alexopoulos, C. Barschel, F.S. Carlier, J.M. Coello de Portugal, M. Ferro-Luzzi, A. Garcia-Tabares, M. Hostettler, O. Karacheban, E.H. Maclean, R. Matev, T. Persson, P.K. Skowroński, R. Tomás, G. Trad, S. Vlachos, B. Würkner CERN, Geneva, Switzerland G.R. Coombs EPFL, Lausanne, Switzerland T.B. Hadavizadeh Oxford University, Physics Department, Oxford, Oxon, United Kingdom M. Hofer TU Vienna, Wien, Austria L. van Riesen-Haupt University of Oxford, Oxford, United Kingdom
	Calibration of a transverse beam profile monitor is of fundamental importance to guarantee the best possible accuracy and reliability of the instrument over time. In LHC the calibration standard for transverse-profile measurements are the wire scanners. Other profile monitors such as beam synchrotron light telescopes and interferometers are calibrated with respect to them. Additional information about single-bunch sizes can be obtained from beam-gas imaging in the LHCb vertex detector, from the transverse convolved beam sizes extracted from luminosity scans at the collision points, and from the evolution of the luminous-region parameters as reconstructed by ATLAS and CMS inner tracker detectors during such scans. For the first time in LHC, a dedicated cross-calibration of all the above-mentioned systems was carried out with beam in 2016. Additionally, dedicated optics measurements were also performed in order to determine with the highest possible accuracy the amplitude function at the interaction points and at the position of the profile monitors. Results of these measurements are presented in this paper.
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MOPIK099	Tuning-Based Design Optimization of CLIC Final Focus System at 3 TeV	760
SUSPSIK047	use link to see paper's listing under its alternate paper code
	F. Plassard, A. Latina, E. Marín, D. Schulte, R. Tomás CERN, Geneva, Switzerland P. Bambade LAL, Orsay, France
	The tuning aims to mitigate static imperfections of the Final Focus System (FFS) for emittance preservation at the Interaction Point (IP). A simulation campaign on the nominal CLIC FFS at 3 TeV have shown the need of rethink the design in order to ease the tuning of the machine. The goal is to optimize the lattice in order to make the FFS more tolerant to misalignments by reducing the strength of the sextupoles. The tuning efficiency is promoted as figure of merit to find the optimal layout of the FFS. A comparative study of the tuning performances have been performed for two L* options.
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MOPIK100	Beam Delivery System Optimization for CLIC 380 GeV	764
	F. Plassard, A. Latina, E. Marín, D. Schulte, R. Tomás CERN, Geneva, Switzerland P. Bambade LAL, Orsay, France
	In the framework of the CLIC rebaselining, the Beam Delivery System (BDS) have been re-optimized for its initial stage at 380 GeV. Two BDS designs with L=4.3 meters and L=6 meters have been investigated. The optimization of the lattices and the beam parameters at the interaction point (IP) have been performed by taking into account their energy upgrade to 3 TeV and the tuning feasibility of the BDS in presence of static imperfections.
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MOPIK108	Tuning Simulations for the CLIC Traditional Beam Delivery System	788
	R.M. Bodenstein, P. Burrows JAI, Oxford, United Kingdom E. Marín, F. Plassard, R. Tomás CERN, Geneva, Switzerland
	As the design of the CLIC Beam Delivery System (BDS) evolves, tuning simulations must be performed on each of the proposed lattice designs to see which system achieves the highest luminosity in the most realistic manner. This work will focus on the tuning simulations performed on the so-called Traditional lattice design for the center-of-mass energy of 3 TeV. The lattice modifications required to target the most important aberrations and the latest tuning results will be presented.
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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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TUPIK097	Improving the Performance of an Orbit Feed-forward Based on Quadrupole Motion at the KEK ATF	1931
	D.R. Bett, C. Charrondière, M. Patecki, J. Pfingstner, D. Schulte, R. Tomás CERN, Geneva, Switzerland P. Burrows, G.B. Christian, C. Perry JAI, Oxford, United Kingdom A. Jeremie IN2P3-LAPP, Annecy-le-Vieux, France K. Kubo, S. Kuroda, T. Naito, T. Okugi, T.T. Tauchi, N. Terunuma KEK, Ibaraki, Japan
	The high luminosity requirement for a future linear collider sets a demanding limit on the beam quality at the Interation Point (IP). Even the natural motion of the ground could misalign the quadrupole magnets to such an extent that the resulting dipole kicks would require compensation. The novel technique described in this paper uses seismometers to measure the positions of the quadrupole magnets in real time and a kicker to counteract the effect of their misalignment. The prototype system deployed at the Accelerator Test Facility (ATF) at KEK in Japan has already demonstrated a reduction in the pulse-to-pulse vertical position jitter of the beam by about 10%. Based on the observed correlation of the beam position to the quadrupole positions the maximum possible jitter reduction from such a system is estimated to be about 25%. This paper details the latest improvements made to the system with the aim of achieving this limit.
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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.
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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.
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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.
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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.
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TUPVA130	CLIC Tuning Performance Under Realistic Error Conditions	2403
	E. Marín, A. Latina, F. Plassard, D. Schulte, R. Tomás CERN, Geneva, Switzerland
	In this paper we present the latest results regarding the tuning study of the baseline design of the CLIC Final Focus System. In previous studies, 90% of the machines reach 90% of the nominal luminosity, when considering beam position monitor errors and transverse misalignments of magnets for a single beam case. In the present study, roll misalignments and strength errors are also included for both e^- and e⁺ beamlines, making the study a more realistic one. First, second and third order knobs are implemented in the tuning procedure to target the most relevant beam size aberrations. In order to minimise the total number of luminosity measurements a simultaneous scan of various knobs has been developed to cope with the non-fully orthogonality of the knobs. The obtained results for single and double beam studies are presented.
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WEOAB2	Correction of Beta-Beating Due to Beam-Beam for the LHC and Its Impact on Dynamic Aperture	2512
	L.E. Medina Medrano, J. Barranco García, X. Buffat, Y. Papaphilippou, T. Pieloni, R. Tomás CERN, Geneva, Switzerland J. Barranco García, T. Pieloni EPFL, Lausanne, Switzerland L.E. Medina Medrano UGTO, Leon, Mexico
	Funding: This work is supported by the European Circular Energy-Frontier Collider Study, H2020 programme under grant agreement no. 654305, by the Swiss State Secretariat for Education, Research and Innovation SERI, and by the Beam project (CONACYT, Mexico). Minimization of the beta-beating at the two main interaction points of the LHC arising from the head-on and long-range beam-beam interactions can be performed by adjusting the strength of quadrupole or sextupole correctors. This compensation scheme is applied to the current LHC optics where the results show a significant reduction of the peak and RMS beta-beating; and the impact on the dynamic aperture is computed. A proposal for a similar strategy to be adopted in the High Luminosity LHC is also discussed.
	Slides WEOAB2 [6.292 MB]
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WEPIK030	Experimental Validation of the Achromatic Telescopic Squeezing Scheme at the LHC	2992
	S.D. Fartoukh, R. Bruce, F.S. Carlier, J.M. Coello de Portugal, A. Garcia-Tabares, E.H. Maclean, L. Malina, A. Mereghetti, D. Mirarchi, T. Persson, M. Pojer, L. Ponce, S. Redaelli, B. Salvachua, P.K. Skowroński, M. Solfaroli, R. Tomás, D. Valuch, A. Wegscheider, J. Wenninger CERN, Geneva, Switzerland
	The Achromatic Telescopic Squeezing (ATS) [1] scheme offers new techniques to deliver unprecedentedly small beam spot size at the interaction points of the ATLAS and CMS experiments of the LHC, while perfectly controlling the chromatic properties of the corresponding optics (linear and non-linear chromaticities, off-momentum beta-beating, spurious dispersion induced by the crossing bumps). The first series of beam tests with ATS optics were achieved during the LHC Run I (2011/2012) for a first validation of the basics of the scheme at small intensity. In 2016, a new generation of more performing ATS optics was developed and more extensively tested in the machine, still with probe beams for optics measurement and correction at β^=10 cm, but also with a few nominal bunches to establish first collisions at nominal β^ (40 cm) and beyond (33 cm), and to analysis the robustness of these optics in terms of collimation and machine protection. The paper will highlight the most relevant and conclusive results which were obtained during this second series of ATS tests. [1] S. Fartoukh , Phys. Rev. ST Accel. Beams 16, 111002
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WEPIK074	Twiss Parameter Measurement and Application to Space Charge Dynamics	3101
	K. Ohmi, S. Igarashi, T. Toyama KEK, Tokai, Ibaraki, Japan H. Harada, S. Hatakeyama JAEA/J-PARC, Tokai-mura, Japan N. Kuroo UTTAC, Tsukuba, Ibaraki, Japan Y. Sato J-PARC, KEK & JAEA, Ibaraki-ken, Japan R. Tomás, A. Wegscheider CERN, Geneva, Switzerland
	We are looking for feasible and quantitative method to evaluate space charge induced beam loss in J-PARC MR. One possible way is space charge simulation and theory based on measured Twiss parameter. Twiss parameter measurement using turn-by-turn monitors is presented. Resonance strengths of lattice magnets and space charge force are estimated by the measured Twiss parameters. Emittance growth and beam loss under the resonance strengths are discussed.
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WEPIK091	Amplitude Dependent Closest Tune Approach Generated by Normal and Skew Octupoles	3147
	E.H. Maclean, T. Persson, R. Tomás CERN, Geneva, Switzerland
	Amplitude dependent closest tune approach, an action dependent analogue of the DQmin generated by linear coupling, was observed in the LHC during Run1. It restricts the accessible resonance free area of the tune diagram and by altering tune spread has the potential to impact upon Landau damping. A theoretical description of such behaviour, generated by normal octupoles and linear coupling has recently been validated in the LHC, however simulation has established that amp-dependent closest approach may also be generated by a combination of normal and skew octupoles. This paper summarizes these simulation based observations.
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WEPIK092	Effect of Linear Coupling on Nonlinear Observables at the LHC	3151
	E.H. Maclean, F.S. Carlier, M. Giovannozzi, T. Persson, R. Tomás CERN, Geneva, Switzerland
	Simulation work during LHC Run 1 established that linear coupling had a large impact on nonlinear observables such amplitude detuning and dynamic aperture. It is generally taken to be the largest single source of uncertainty in the modelling of the LHC's nonlinear single particle dynamics. Measurements in 2016 sought to confirm this impact of linear coupling with beam. This paper summarizes the observed influence of linear coupling on various nonlinear observables in the LHC.
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WEPIK093	New Methods for Measurement of Nonlinear Errors in LHC Experimental IRs and Their Application in the HL-LHC	3155
	E.H. Maclean, F.S. Carlier, J.M. Coello de Portugal, A. Garcia-Tabares, M. Giovannozzi, L. Malina, T. Persson, P.K. Skowroński, R. Tomás CERN, Geneva, Switzerland
	Studies of nonlinear errors in LHC experimental insertions (IRs) during Run 1 were based upon feed-down to tune and coupling from the crossing angle orbit bumps. Useful for validating the magnetic model, this method alone is of limited use to understand discrepancies between magnetic and beam-based measurement. Feed-down from high-order multipoles is also difficult to observe. During Run 2 several alternative methods were tested in the LHC. This paper summarizes the results of these tests, and comments on their potential application to the High-Luminosity LHC upgrade.
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Paper

Title

Page

Linear and Nonlinear Optics Measurements With Multiturn Data at PETRA III

170

I.V. Agapov, M. Bieler, H. Ehrlichmann, J. Keil, J. Klute, G. Kube, G.K. Sahoo, F. Schmidt-Föhre, R. Wanzenberg
DESY, Hamburg, Germany
R. Tomás, A. Wegscheider
CERN, Geneva, Switzerland

At Petra III measuring multiturn beam response to pulsed and continuous excitations allows linear and nonlinear (e.g. frequency maps) optics parameter determination. We describe the measurement setup, approaches to optics parameter determination, and the measurement results for Petra III.

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MOPAB130

Cross-Calibration of the LHC Transverse Beam-Profile Monitors

437

R. Alemany-Fernández, F. Alessio, A. Alexopoulos, C. Barschel, F.S. Carlier, J.M. Coello de Portugal, M. Ferro-Luzzi, A. Garcia-Tabares, M. Hostettler, O. Karacheban, E.H. Maclean, R. Matev, T. Persson, P.K. Skowroński, R. Tomás, G. Trad, S. Vlachos, B. Würkner
CERN, Geneva, Switzerland
G.R. Coombs
EPFL, Lausanne, Switzerland
T.B. Hadavizadeh
Oxford University, Physics Department, Oxford, Oxon, United Kingdom
M. Hofer
TU Vienna, Wien, Austria
L. van Riesen-Haupt
University of Oxford, Oxford, United Kingdom

Calibration of a transverse beam profile monitor is of fundamental importance to guarantee the best possible accuracy and reliability of the instrument over time. In LHC the calibration standard for transverse-profile measurements are the wire scanners. Other profile monitors such as beam synchrotron light telescopes and interferometers are calibrated with respect to them. Additional information about single-bunch sizes can be obtained from beam-gas imaging in the LHCb vertex detector, from the transverse convolved beam sizes extracted from luminosity scans at the collision points, and from the evolution of the luminous-region parameters as reconstructed by ATLAS and CMS inner tracker detectors during such scans. For the first time in LHC, a dedicated cross-calibration of all the above-mentioned systems was carried out with beam in 2016. Additionally, dedicated optics measurements were also performed in order to determine with the highest possible accuracy the amplitude function at the interaction points and at the position of the profile monitors. Results of these measurements are presented in this paper.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB130

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MOPIK099

Tuning-Based Design Optimization of CLIC Final Focus System at 3 TeV

760

SUSPSIK047

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

F. Plassard, A. Latina, E. Marín, D. Schulte, R. Tomás
CERN, Geneva, Switzerland
P. Bambade
LAL, Orsay, France

The tuning aims to mitigate static imperfections of the Final Focus System (FFS) for emittance preservation at the Interaction Point (IP). A simulation campaign on the nominal CLIC FFS at 3 TeV have shown the need of rethink the design in order to ease the tuning of the machine. The goal is to optimize the lattice in order to make the FFS more tolerant to misalignments by reducing the strength of the sextupoles. The tuning efficiency is promoted as figure of merit to find the optimal layout of the FFS. A comparative study of the tuning performances have been performed for two L* options.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPIK099

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MOPIK100

Beam Delivery System Optimization for CLIC 380 GeV

764

F. Plassard, A. Latina, E. Marín, D. Schulte, R. Tomás
CERN, Geneva, Switzerland
P. Bambade
LAL, Orsay, France

In the framework of the CLIC rebaselining, the Beam Delivery System (BDS) have been re-optimized for its initial stage at 380 GeV. Two BDS designs with L*=4.3 meters and L*=6 meters have been investigated. The optimization of the lattices and the beam parameters at the interaction point (IP) have been performed by taking into account their energy upgrade to 3 TeV and the tuning feasibility of the BDS in presence of static imperfections.

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MOPIK108

Tuning Simulations for the CLIC Traditional Beam Delivery System

788

R.M. Bodenstein, P. Burrows
JAI, Oxford, United Kingdom
E. Marín, F. Plassard, R. Tomás
CERN, Geneva, Switzerland

As the design of the CLIC Beam Delivery System (BDS) evolves, tuning simulations must be performed on each of the proposed lattice designs to see which system achieves the highest luminosity in the most realistic manner. This work will focus on the tuning simulations performed on the so-called Traditional lattice design for the center-of-mass energy of 3 TeV. The lattice modifications required to target the most important aberrations and the latest tuning results will be presented.

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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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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK089

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TUPIK097

Improving the Performance of an Orbit Feed-forward Based on Quadrupole Motion at the KEK ATF

1931

D.R. Bett, C. Charrondière, M. Patecki, J. Pfingstner, D. Schulte, R. Tomás
CERN, Geneva, Switzerland
P. Burrows, G.B. Christian, C. Perry
JAI, Oxford, United Kingdom
A. Jeremie
IN2P3-LAPP, Annecy-le-Vieux, France
K. Kubo, S. Kuroda, T. Naito, T. Okugi, T.T. Tauchi, N. Terunuma
KEK, Ibaraki, Japan

The high luminosity requirement for a future linear collider sets a demanding limit on the beam quality at the Interation Point (IP). Even the natural motion of the ground could misalign the quadrupole magnets to such an extent that the resulting dipole kicks would require compensation. The novel technique described in this paper uses seismometers to measure the positions of the quadrupole magnets in real time and a kicker to counteract the effect of their misalignment. The prototype system deployed at the Accelerator Test Facility (ATF) at KEK in Japan has already demonstrated a reduction in the pulse-to-pulse vertical position jitter of the beam by about 10%. Based on the observed correlation of the beam position to the quadrupole positions the maximum possible jitter reduction from such a system is estimated to be about 25%. This paper details the latest improvements made to the system with the aim of achieving this limit.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK097

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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.

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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.

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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.

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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.

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TUPVA130

CLIC Tuning Performance Under Realistic Error Conditions

2403

E. Marín, A. Latina, F. Plassard, D. Schulte, R. Tomás
CERN, Geneva, Switzerland

In this paper we present the latest results regarding the tuning study of the baseline design of the CLIC Final Focus System. In previous studies, 90% of the machines reach 90% of the nominal luminosity, when considering beam position monitor errors and transverse misalignments of magnets for a single beam case. In the present study, roll misalignments and strength errors are also included for both e^- and e⁺ beamlines, making the study a more realistic one. First, second and third order knobs are implemented in the tuning procedure to target the most relevant beam size aberrations. In order to minimise the total number of luminosity measurements a simultaneous scan of various knobs has been developed to cope with the non-fully orthogonality of the knobs. The obtained results for single and double beam studies are presented.

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WEOAB2

Correction of Beta-Beating Due to Beam-Beam for the LHC and Its Impact on Dynamic Aperture

2512

L.E. Medina Medrano, J. Barranco García, X. Buffat, Y. Papaphilippou, T. Pieloni, R. Tomás
CERN, Geneva, Switzerland
J. Barranco García, T. Pieloni
EPFL, Lausanne, Switzerland
L.E. Medina Medrano
UGTO, Leon, Mexico

Funding: This work is supported by the European Circular Energy-Frontier Collider Study, H2020 programme under grant agreement no. 654305, by the Swiss State Secretariat for Education, Research and Innovation SERI, and by the Beam project (CONACYT, Mexico).
Minimization of the beta-beating at the two main interaction points of the LHC arising from the head-on and long-range beam-beam interactions can be performed by adjusting the strength of quadrupole or sextupole correctors. This compensation scheme is applied to the current LHC optics where the results show a significant reduction of the peak and RMS beta-beating; and the impact on the dynamic aperture is computed. A proposal for a similar strategy to be adopted in the High Luminosity LHC is also discussed.

Slides WEOAB2 [6.292 MB]

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WEPIK030

Experimental Validation of the Achromatic Telescopic Squeezing Scheme at the LHC

2992

S.D. Fartoukh, R. Bruce, F.S. Carlier, J.M. Coello de Portugal, A. Garcia-Tabares, E.H. Maclean, L. Malina, A. Mereghetti, D. Mirarchi, T. Persson, M. Pojer, L. Ponce, S. Redaelli, B. Salvachua, P.K. Skowroński, M. Solfaroli, R. Tomás, D. Valuch, A. Wegscheider, J. Wenninger
CERN, Geneva, Switzerland

The Achromatic Telescopic Squeezing (ATS) [1] scheme offers new techniques to deliver unprecedentedly small beam spot size at the interaction points of the ATLAS and CMS experiments of the LHC, while perfectly controlling the chromatic properties of the corresponding optics (linear and non-linear chromaticities, off-momentum beta-beating, spurious dispersion induced by the crossing bumps). The first series of beam tests with ATS optics were achieved during the LHC Run I (2011/2012) for a first validation of the basics of the scheme at small intensity. In 2016, a new generation of more performing ATS optics was developed and more extensively tested in the machine, still with probe beams for optics measurement and correction at β^*=10 cm, but also with a few nominal bunches to establish first collisions at nominal β^* (40 cm) and beyond (33 cm), and to analysis the robustness of these optics in terms of collimation and machine protection. The paper will highlight the most relevant and conclusive results which were obtained during this second series of ATS tests.
[1] S. Fartoukh , Phys. Rev. ST Accel. Beams 16, 111002

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WEPIK074

Twiss Parameter Measurement and Application to Space Charge Dynamics

3101

K. Ohmi, S. Igarashi, T. Toyama
KEK, Tokai, Ibaraki, Japan
H. Harada, S. Hatakeyama
JAEA/J-PARC, Tokai-mura, Japan
N. Kuroo
UTTAC, Tsukuba, Ibaraki, Japan
Y. Sato
J-PARC, KEK & JAEA, Ibaraki-ken, Japan
R. Tomás, A. Wegscheider
CERN, Geneva, Switzerland

We are looking for feasible and quantitative method to evaluate space charge induced beam loss in J-PARC MR. One possible way is space charge simulation and theory based on measured Twiss parameter. Twiss parameter measurement using turn-by-turn monitors is presented. Resonance strengths of lattice magnets and space charge force are estimated by the measured Twiss parameters. Emittance growth and beam loss under the resonance strengths are discussed.

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WEPIK091

Amplitude Dependent Closest Tune Approach Generated by Normal and Skew Octupoles

3147

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

Amplitude dependent closest tune approach, an action dependent analogue of the DQmin generated by linear coupling, was observed in the LHC during Run1. It restricts the accessible resonance free area of the tune diagram and by altering tune spread has the potential to impact upon Landau damping. A theoretical description of such behaviour, generated by normal octupoles and linear coupling has recently been validated in the LHC, however simulation has established that amp-dependent closest approach may also be generated by a combination of normal and skew octupoles. This paper summarizes these simulation based observations.

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WEPIK092

Effect of Linear Coupling on Nonlinear Observables at the LHC

3151

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

Simulation work during LHC Run 1 established that linear coupling had a large impact on nonlinear observables such amplitude detuning and dynamic aperture. It is generally taken to be the largest single source of uncertainty in the modelling of the LHC's nonlinear single particle dynamics. Measurements in 2016 sought to confirm this impact of linear coupling with beam. This paper summarizes the observed influence of linear coupling on various nonlinear observables in the LHC.

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WEPIK093

New Methods for Measurement of Nonlinear Errors in LHC Experimental IRs and Their Application in the HL-LHC

3155

E.H. Maclean, F.S. Carlier, J.M. Coello de Portugal, A. Garcia-Tabares, M. Giovannozzi, L. Malina, T. Persson, P.K. Skowroński, R. Tomás
CERN, Geneva, Switzerland

Studies of nonlinear errors in LHC experimental insertions (IRs) during Run 1 were based upon feed-down to tune and coupling from the crossing angle orbit bumps. Useful for validating the magnetic model, this method alone is of limited use to understand discrepancies between magnetic and beam-based measurement. Feed-down from high-order multipoles is also difficult to observe. During Run 2 several alternative methods were tested in the LHC. This paper summarizes the results of these tests, and comments on their potential application to the High-Luminosity LHC upgrade.

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