IPAC2022 - List of Authors (Tomas, R.)

Paper	Title	Page
MOPOST003	BBQ and Doughnut Beams: A Tasty Recipe for Measuring Amplitude Dependence of the Closest Tune Approach	42
	E.H. Maclean, F.S. Carlier, T.H.B. Persson, R. Tomás García CERN, Meyrin, Switzerland
	Beam-based observations and theoretical studies have demonstrated the existence of a significant amplitude dependence of the closest tune approach (ADECTA) in the LHC. This effect has the potential to generate significant distortion of the tune footprint and thus is of interest in regard to Landau damping. Conventionally ADECTA has been studied through saturation of tune separation with action during amplitude-detuning type measurements. In this paper, an alternative measurement technique is proposed and results of initial tests with beam are presented. The novel technique attempts to measure ADECTA by performing a classical closest approach tune scan, using proton beams in the LHC, which have been kicked and allowed to decohere, effectively giving a large action doughnut beam. It is shown that the tune and closest approach of the doughnut beams can be measured using the existing LHC Base-Band tune (BBQ) measurement system, and an amplitude dependence can be observed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOST003
About •	Received ※ 08 June 2022 — Revised ※ 20 June 2022 — Accepted ※ 12 July 2022 — Issue date ※ 22 June 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPOPT047	Experimental Demonstration of Machine Learning Application in LHC Optics Commissioning	359
	E. Fol, F.S. Carlier, J. Dilly, M. Hofer, J. Keintzel, M. Le Garrec, E.H. Maclean, T.H.B. Persson, F. Soubelet, R. Tomás García, A. Wegscheider CERN, Meyrin, Switzerland J.F. Cardona UNAL, Bogota D.C, Colombia
	Recently, we conducted successful studies on the suitability of machine learning (ML) methods for optics measurements and corrections, incorporating novel ML-based methods for local optics corrections and reconstruction of optics functions. After performing extensive verifications on simulations and past measurement data, the newly developed techniques became operational in the LHC commissioning 2022. We present the experimental results obtained with the ML-based methods and discuss future improvements. Besides, we also report on improving the Beam Position Monitor (BPM) diagnostics with the help of the anomaly detection technique capable to identify malfunctioning BPMs along with their possible fault causes.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOPT047
About •	Received ※ 07 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 06 July 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPOTK032	An N-BPM Momentum Reconstruction for Linear Transverse Coupling Measurements in LHC and HL-LHC	519
	A. Wegscheider, R. Tomás García CERN, Meyrin, Switzerland
	The measurement and control of linear transverse coupling is important for the operation of an accelerator. The calculation of the linear transverse coupling resonance driving terms (RDTs) ’1001 and ’1010 relies on the complex spectrum of the turn-by-turn motion. To obtain the complex signal, a reconstruction of the particle motion is needed. For this purpose, the signal of a second BPM with a suitable phase shift is usually used. In this work, we explore the possibility of including more BPMs in the reconstruction of the transverse momentum, which could reduce the effects of statistical errors and systematic uncertainties. This, in turn, could improve the precision and accuracy of the RDTs, which could be of great benefit for locations where an exact knowledge of the transverse coupling or other RDTs is important. We present the development of a new method to reconstruct the particle’s momentum that uses a statistical analysis of several nearby BPMs. The improved precision is demonstrated via simulations of LHC and HL-LHC lattices.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOTK032
About •	Received ※ 08 June 2022 — Revised ※ 23 June 2022 — Accepted ※ 23 June 2022 — Issue date ※ 27 June 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUOZSP1	Prospects for Optics Measuements in FCC-ee	827
	J. Keintzel, R. Tomás García, F. Zimmermann CERN, Meyrin, Switzerland
	Within the framework of the Future Circular Collider Feasibility Study, the design of the electron-positron collider FCC-ee is optimised, as a possible future double collider ring, currently foreseen to start operation during the 2040s. With close to 100 km of circumference and strong synchrotron radiation damping at highest beam energy, adequate beam measurements are needed to control the optics at the desired level. Various possible techniques to measure the optics in FCC-ee are explored, including the option of turn-by-turn measurements in combination with an AC-dipole.
	Slides TUOZSP1 [2.738 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUOZSP1
About •	Received ※ 08 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 28 June 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPOST007	Centre-of-Mass Energy in FCC-ee	1683
	J. Keintzel, R. Tomás García, F. Zimmermann CERN, Meyrin, Switzerland A.P. Blondel DPNC, Genève, Switzerland D.N. Shatilov BINP SB RAS, Novosibirsk, Russia
	The Future Circular electron-positron Collider (FCC-ee) is designed for high precision particle physics experiments. This demands a precise knowledge of the beam energies, obtained by resonant depolarization, and from which the center-of-mass energy and possible boosts at all interaction points are then determined. At the highest beam energy mode of 182.5 GeV, the energy loss due to synchrotron radiation is about 10 GeV per revolution. Hence, not only the location of the RF cavities, but also a precise control of the optics and understanding of beam dynamics, are crucial. In the studies presented here, different possible locations of the RF-cavities are considered, when calculating the beam energies over the machine circumference, including energy losses from crossing angles, a non-homogeneous dipole distribution, and an estimate of the beamstrahlung effect at the collision point.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOST007
About •	Received ※ 08 June 2022 — Revised ※ 17 June 2022 — Accepted ※ 24 June 2022 — Issue date ※ 27 June 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPOST008	Optics Correction Strategy for Run 3 of the LHC	1687
	T.H.B. Persson, F.S. Carlier, A. Costa Ojeda, J. Dilly, V. Ferrentino, E. Fol, H. García Morales, M. Hofer, E.J. Høydalsvik, J. Keintzel, M. Le Garrec, E.H. Maclean, L. Malina, F. Soubelet, R. Tomás García, A. Wegscheider, L. van Riesen-Haupt CERN, Meyrin, Switzerland J.F. Cardona UNAL, Bogota D.C, Colombia
	After almost 4 years of shutdown the LHC is again operational in 2022. Experience from the previous Long Shutdown (LS) has shown that the local errors around the triplet magnets changed significantly and it is likely we will again see different errors in 2022. In the LHC there is an interplay between the linear and the nonlinear correction which can make the corrections difficult and time-consuming to find. In this article, we describe the measurements and corrections performed during the commissioning in 2022 in order to control both the linear and the nonlinear optics to high precision.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOST008
About •	Received ※ 08 June 2022 — Revised ※ 25 June 2022 — Accepted ※ 04 July 2022 — Issue date ※ 10 July 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPOPT007	First Interaction Region Local Coupling Corrections in the LHC Run 3	1838
	F. Soubelet, T.H.B. Persson, R. Tomás García CERN, Meyrin, Switzerland Ö. Apsimon, C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom
	Funding: This research is supported by the LIV. DAT Center for Doctoral Training, STFC and the European Organization for Nuclear Research The successful operation of large scale particle accelerators depends on the precise correction of unavoidable magnetic field or magnet alignment errors present in the machine. During the LHC Run 2, local linear coupling in the interaction regions (IR) was shown to have a significant impact on the beam size, making its proper handling a necessity for Run 3 and the High Luminosity LHC (HL-LHC). A new approach to accurately minimise the local IR linear coupling based on correlated external variables such as the \|C-\| had been proposed, which relies on the application of a rigid waist shift in order to create an asymmetry in the IR optics. In this contribution, preliminary corrections from the 2021 beam test and the early 2022 commissioning are presented, as well as first results of the new method’s experimental configuration tests in the LHC Run 3 commissioning.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOPT007
About •	Received ※ 03 June 2022 — Revised ※ 15 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 19 June 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPOPT008	Supervised Machine Learning for Local Coupling Sources Detection in the LHC	1842
SUSPMF001	use link to see paper's listing under its alternate paper code
	F. Soubelet, T.H.B. Persson, R. Tomás García CERN, Meyrin, Switzerland Ö. Apsimon, C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom
	Funding: This research is supported by the LIV. DAT Center for Doctoral Training, STFC and the European Organization for Nuclear Research Local interaction region (IR) linear coupling in the LHC has been shown to have a negative impact on beam size and luminosity, making its accurate correction for Run 3 and beyond a necessity. In view of determining corrections, supervised machine learning has been applied to the detection of linear coupling sources, showing promising results in simulations. An evaluation of different applied models is given, followed by the presentation of further possible application concepts for linear coupling corrections using machine learning.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOPT008
About •	Received ※ 03 June 2022 — Revised ※ 15 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 29 June 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPOPT009	Operational Scenario of First High Luminosity LHC Run	1846
	R. Tomás García, G. Arduini, P. Baudrenghien, R. Bruce, O.S. Brüning, X. Buffat, R. Calaga, F. Cerutti, R. De Maria, J. Dilly, I. Efthymiopoulos, M. Giovannozzi, P.D. Hermes, G. Iadarola, O.R. Jones, S. Kostoglou, E.H. Maclean, N. Mounet, E. Métral, Y. Papaphilippou, S. Redaelli, G. Sterbini, H. Timko, F.F. Van der Veken, J. Wenninger, M. Zerlauth CERN, Meyrin, Switzerland
	A new scenario for the first operational run of the HL-LHC era (Run 4) has been recently developed to accommodate a period of performance ramp-up to achieve an annual integrated luminosity close to the nominal HL-LHC design. The operational scenario in terms of beam parameters and machine settings, as well as the different phases, are described here along with the impact of potential delays on key hardware components.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOPT009
About •	Received ※ 19 May 2022 — Revised ※ 15 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 09 July 2022
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WEPOPT010	Progress on Action Phase Jump for LHC Local Optics Correction	1850
	J.F. Cardona, Y. Rodriguez Garcia UNAL, Bogota D.C, Colombia H. García Morales, M. Hofer, E.H. Maclean, T.H.B. Persson, R. Tomás García CERN, Meyrin, Switzerland Y. Rodriguez Garcia UAN, Bogotá D.C., Colombia
	The correction of the local optics at the Interaction Regions of the LHC is crucial to ensure a good performance of the machine. This is even more important for the future LHC upgrade, HL-LHC, where the optics is more sensitive to magnetic errors. For that reason, it is important to explore alternative techniques for local optics corrections. In this paper, we evaluate the performance of the Action Phase Jump method for optics correction in the LHC and the HL-LHC and explore ways to integrate this technique in regular operations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOPT010
About •	Received ※ 08 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 18 June 2022
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WEPOPT011	Modelling FCC-ee Using MADX	1854
	L. van Riesen-Haupt, H. Burkhardt, T.H.B. Persson, R. Tomás García CERN, Meyrin, Switzerland
	We present the latest developments for simulating FCC-ee using CERN’s MADX software. Along with updated benchmark studies, we describe how the latest MADX updates can facilitate the simulation of FCC-ee design features, including improvements in tapering and different options for implementing a tilted solenoid.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOPT011
About •	Received ※ 08 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 08 July 2022
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WEPOPT012	MAD-X for Future Accelerators	1858
	T.H.B. Persson, H. Burkhardt, R. De Maria, L. Deniau, E.J. Høydalsvik, A. Latina, P.K. Skowroński, R. Tomás García, L. van Riesen-Haupt CERN, Meyrin, Switzerland
	The development of MAD-X was started more than 20 years ago and it still remains the main tool for single particle dynamics for both optics design, error studies as well as for operational model-based software at CERN. In this article, we outline some of the recent development of MAD-X and plans for the future. In particular, we focus on the development of the twiss module used to calculate optics functions in MAD-X which is based on first and second order matrices. These have traditionally been calculated as an expansion around the ideal orbit. In this paper, we describe explicitly how an expansion around the closed orbit can be employed instead, in order to get more precise results. We also describe the latest development of the beam-beam long range wire compensator in MAD-X, an element that has been implemented using the aforementioned approach.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOPT012
About •	Received ※ 08 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 23 June 2022 — Issue date ※ 01 July 2022
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WEPOPT059	Corrections of Systematic Normal Decapole Field Errors in the HL-LHC Separation/Recombination Dipoles	1991
	J. Dilly, M. Giovannozzi, R. Tomás García, F.F. Van der Veken CERN, Meyrin, Switzerland
	Funding: This work has been supported by the HiLumi Project and been sponsored by the Wolfgang Gentner Programme of the German Federal Ministry of Education and Re-search. Magnetic measurements revealed that the normal decapole (b5) errors of the recombination dipoles (D2) could have a systematic component of up to 11 units. Based on previous studies, it was predicted that the current corrections would not be able to compensate this, thereby leading to a degradation of the dynamic aperture by about 0.5 - 1 ’. On the other hand, the separation dipole D1 is expected to have a systematic b5 component of 6-7 units and its contribution to the resonance driving terms will partly compensate the effect of D2, due to the opposite field strength of the main component. Simulations were performed with the HL-LHC V1.4 lattice to test these concerns and to verify the compensation assumption. In addition, various normal decapole resonance driving terms were examined for correction, the results of which are presented in this contribution.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOPT059
About •	Received ※ 07 June 2022 — Revised ※ 15 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 03 July 2022
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WEPOPT060	Controlling Landau Damping via Feed-Down From High-Order Correctors in the LHC and HL-LHC	1995
SUSPMF005	use link to see paper's listing under its alternate paper code
	J. Dilly, E.H. Maclean, R. Tomás García CERN, Meyrin, Switzerland
	Funding: This work has been supported by the HiLumi Project and been sponsored by the Wolfgang Gentner Programme of the German Federal Ministry of Education and Re-search. Amplitude detuning measurements in the LHC have shown that a significant amount of detuning is generated in Beam 1 via feed-down from decapole and dodecapole field errors in the triplets of the experiment insertion regions, while in Beam 2 this detuning is negligible. In this study, we investigate the cause of this behavior and we attempt to find corrections that use the feed-down from the nonlinear correctors in the insertion region for amplitude detuning.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOPT060
About •	Received ※ 07 June 2022 — Revised ※ 15 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 06 July 2022
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WEPOPT061	A Flexible Nonlinear Resonance Driving Term Based Correction Algorithm with Feed-Down	1999
	J. Dilly, R. Tomás García CERN, Meyrin, Switzerland
	Funding: This work has been supported by the HiLumi Project and been sponsored by the Wolfgang Gentner Programme of the German Federal Ministry of Education and Re-search. The optics in the insertion regions of the LHC and its upgrade project the High Luminosity LHC are very sensitive to local magnetic errors, due to the extremely high beta-functions. In collision optics, the non-zero closed orbit in the same region leads to a "feed-down" of high-order errors to lower orders, causing additional effects detrimental to beam lifetime. An extension to the well-established method for correcting these errors by locally suppressing resonance driving terms has been undertaken, not only taking this feed-down into account, but also adding the possibility of utilizing it such that the powering of higher-order correctors will compensate for lower order errors. Existing correction schemes have also operated on the assumption of (anti-)symmetric beta-functions of the optics in the two rings. This assumption can fail for a multitude of reasons, such as inherently asymmetric optics and unevenly distributed errors. In this respect, an extension of this correction scheme has been developed, removing the need for symmetry by operating on the two separate optics of the beams simultaneously.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOPT061
About •	Received ※ 07 June 2022 — Accepted ※ 14 June 2022 — Issue date ※ 15 June 2022
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Paper

Title

Page

BBQ and Doughnut Beams: A Tasty Recipe for Measuring Amplitude Dependence of the Closest Tune Approach

42

E.H. Maclean, F.S. Carlier, T.H.B. Persson, R. Tomás García
CERN, Meyrin, Switzerland

Beam-based observations and theoretical studies have demonstrated the existence of a significant amplitude dependence of the closest tune approach (ADECTA) in the LHC. This effect has the potential to generate significant distortion of the tune footprint and thus is of interest in regard to Landau damping. Conventionally ADECTA has been studied through saturation of tune separation with action during amplitude-detuning type measurements. In this paper, an alternative measurement technique is proposed and results of initial tests with beam are presented. The novel technique attempts to measure ADECTA by performing a classical closest approach tune scan, using proton beams in the LHC, which have been kicked and allowed to decohere, effectively giving a large action doughnut beam. It is shown that the tune and closest approach of the doughnut beams can be measured using the existing LHC Base-Band tune (BBQ) measurement system, and an amplitude dependence can be observed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOST003

About •

Received ※ 08 June 2022 — Revised ※ 20 June 2022 — Accepted ※ 12 July 2022 — Issue date ※ 22 June 2022

Cite •

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

MOPOPT047

Experimental Demonstration of Machine Learning Application in LHC Optics Commissioning

359

E. Fol, F.S. Carlier, J. Dilly, M. Hofer, J. Keintzel, M. Le Garrec, E.H. Maclean, T.H.B. Persson, F. Soubelet, R. Tomás García, A. Wegscheider
CERN, Meyrin, Switzerland
J.F. Cardona
UNAL, Bogota D.C, Colombia

Recently, we conducted successful studies on the suitability of machine learning (ML) methods for optics measurements and corrections, incorporating novel ML-based methods for local optics corrections and reconstruction of optics functions. After performing extensive verifications on simulations and past measurement data, the newly developed techniques became operational in the LHC commissioning 2022. We present the experimental results obtained with the ML-based methods and discuss future improvements. Besides, we also report on improving the Beam Position Monitor (BPM) diagnostics with the help of the anomaly detection technique capable to identify malfunctioning BPMs along with their possible fault causes.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOPT047

About •

Received ※ 07 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 06 July 2022

Cite •

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

MOPOTK032

An N-BPM Momentum Reconstruction for Linear Transverse Coupling Measurements in LHC and HL-LHC

519

A. Wegscheider, R. Tomás García
CERN, Meyrin, Switzerland

The measurement and control of linear transverse coupling is important for the operation of an accelerator. The calculation of the linear transverse coupling resonance driving terms (RDTs) ’1001 and ’1010 relies on the complex spectrum of the turn-by-turn motion. To obtain the complex signal, a reconstruction of the particle motion is needed. For this purpose, the signal of a second BPM with a suitable phase shift is usually used. In this work, we explore the possibility of including more BPMs in the reconstruction of the transverse momentum, which could reduce the effects of statistical errors and systematic uncertainties. This, in turn, could improve the precision and accuracy of the RDTs, which could be of great benefit for locations where an exact knowledge of the transverse coupling or other RDTs is important. We present the development of a new method to reconstruct the particle’s momentum that uses a statistical analysis of several nearby BPMs. The improved precision is demonstrated via simulations of LHC and HL-LHC lattices.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOTK032

About •

Received ※ 08 June 2022 — Revised ※ 23 June 2022 — Accepted ※ 23 June 2022 — Issue date ※ 27 June 2022

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

TUOZSP1

Prospects for Optics Measuements in FCC-ee

827

J. Keintzel, R. Tomás García, F. Zimmermann
CERN, Meyrin, Switzerland

Within the framework of the Future Circular Collider Feasibility Study, the design of the electron-positron collider FCC-ee is optimised, as a possible future double collider ring, currently foreseen to start operation during the 2040s. With close to 100 km of circumference and strong synchrotron radiation damping at highest beam energy, adequate beam measurements are needed to control the optics at the desired level. Various possible techniques to measure the optics in FCC-ee are explored, including the option of turn-by-turn measurements in combination with an AC-dipole.

Slides TUOZSP1 [2.738 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUOZSP1

About •

Received ※ 08 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 28 June 2022

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

WEPOST007

Centre-of-Mass Energy in FCC-ee

1683

J. Keintzel, R. Tomás García, F. Zimmermann
CERN, Meyrin, Switzerland
A.P. Blondel
DPNC, Genève, Switzerland
D.N. Shatilov
BINP SB RAS, Novosibirsk, Russia

The Future Circular electron-positron Collider (FCC-ee) is designed for high precision particle physics experiments. This demands a precise knowledge of the beam energies, obtained by resonant depolarization, and from which the center-of-mass energy and possible boosts at all interaction points are then determined. At the highest beam energy mode of 182.5 GeV, the energy loss due to synchrotron radiation is about 10 GeV per revolution. Hence, not only the location of the RF cavities, but also a precise control of the optics and understanding of beam dynamics, are crucial. In the studies presented here, different possible locations of the RF-cavities are considered, when calculating the beam energies over the machine circumference, including energy losses from crossing angles, a non-homogeneous dipole distribution, and an estimate of the beamstrahlung effect at the collision point.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOST007

About •

Received ※ 08 June 2022 — Revised ※ 17 June 2022 — Accepted ※ 24 June 2022 — Issue date ※ 27 June 2022

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

WEPOST008

Optics Correction Strategy for Run 3 of the LHC

1687

T.H.B. Persson, F.S. Carlier, A. Costa Ojeda, J. Dilly, V. Ferrentino, E. Fol, H. García Morales, M. Hofer, E.J. Høydalsvik, J. Keintzel, M. Le Garrec, E.H. Maclean, L. Malina, F. Soubelet, R. Tomás García, A. Wegscheider, L. van Riesen-Haupt
CERN, Meyrin, Switzerland
J.F. Cardona
UNAL, Bogota D.C, Colombia

After almost 4 years of shutdown the LHC is again operational in 2022. Experience from the previous Long Shutdown (LS) has shown that the local errors around the triplet magnets changed significantly and it is likely we will again see different errors in 2022. In the LHC there is an interplay between the linear and the nonlinear correction which can make the corrections difficult and time-consuming to find. In this article, we describe the measurements and corrections performed during the commissioning in 2022 in order to control both the linear and the nonlinear optics to high precision.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOST008

About •

Received ※ 08 June 2022 — Revised ※ 25 June 2022 — Accepted ※ 04 July 2022 — Issue date ※ 10 July 2022

Cite •

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

WEPOPT007

First Interaction Region Local Coupling Corrections in the LHC Run 3

1838

F. Soubelet, T.H.B. Persson, R. Tomás García
CERN, Meyrin, Switzerland
Ö. Apsimon, C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Funding: This research is supported by the LIV. DAT Center for Doctoral Training, STFC and the European Organization for Nuclear Research
The successful operation of large scale particle accelerators depends on the precise correction of unavoidable magnetic field or magnet alignment errors present in the machine. During the LHC Run 2, local linear coupling in the interaction regions (IR) was shown to have a significant impact on the beam size, making its proper handling a necessity for Run 3 and the High Luminosity LHC (HL-LHC). A new approach to accurately minimise the local IR linear coupling based on correlated external variables such as the |C-| had been proposed, which relies on the application of a rigid waist shift in order to create an asymmetry in the IR optics. In this contribution, preliminary corrections from the 2021 beam test and the early 2022 commissioning are presented, as well as first results of the new method’s experimental configuration tests in the LHC Run 3 commissioning.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOPT007

About •

Received ※ 03 June 2022 — Revised ※ 15 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 19 June 2022

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

WEPOPT008

Supervised Machine Learning for Local Coupling Sources Detection in the LHC

1842

SUSPMF001

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

F. Soubelet, T.H.B. Persson, R. Tomás García
CERN, Meyrin, Switzerland
Ö. Apsimon, C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Funding: This research is supported by the LIV. DAT Center for Doctoral Training, STFC and the European Organization for Nuclear Research
Local interaction region (IR) linear coupling in the LHC has been shown to have a negative impact on beam size and luminosity, making its accurate correction for Run 3 and beyond a necessity. In view of determining corrections, supervised machine learning has been applied to the detection of linear coupling sources, showing promising results in simulations. An evaluation of different applied models is given, followed by the presentation of further possible application concepts for linear coupling corrections using machine learning.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOPT008

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Received ※ 03 June 2022 — Revised ※ 15 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 29 June 2022

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WEPOPT009

Operational Scenario of First High Luminosity LHC Run

1846

R. Tomás García, G. Arduini, P. Baudrenghien, R. Bruce, O.S. Brüning, X. Buffat, R. Calaga, F. Cerutti, R. De Maria, J. Dilly, I. Efthymiopoulos, M. Giovannozzi, P.D. Hermes, G. Iadarola, O.R. Jones, S. Kostoglou, E.H. Maclean, N. Mounet, E. Métral, Y. Papaphilippou, S. Redaelli, G. Sterbini, H. Timko, F.F. Van der Veken, J. Wenninger, M. Zerlauth
CERN, Meyrin, Switzerland

A new scenario for the first operational run of the HL-LHC era (Run 4) has been recently developed to accommodate a period of performance ramp-up to achieve an annual integrated luminosity close to the nominal HL-LHC design. The operational scenario in terms of beam parameters and machine settings, as well as the different phases, are described here along with the impact of potential delays on key hardware components.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOPT009

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Received ※ 19 May 2022 — Revised ※ 15 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 09 July 2022

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WEPOPT010

Progress on Action Phase Jump for LHC Local Optics Correction

1850

J.F. Cardona, Y. Rodriguez Garcia
UNAL, Bogota D.C, Colombia
H. García Morales, M. Hofer, E.H. Maclean, T.H.B. Persson, R. Tomás García
CERN, Meyrin, Switzerland
Y. Rodriguez Garcia
UAN, Bogotá D.C., Colombia

The correction of the local optics at the Interaction Regions of the LHC is crucial to ensure a good performance of the machine. This is even more important for the future LHC upgrade, HL-LHC, where the optics is more sensitive to magnetic errors. For that reason, it is important to explore alternative techniques for local optics corrections. In this paper, we evaluate the performance of the Action Phase Jump method for optics correction in the LHC and the HL-LHC and explore ways to integrate this technique in regular operations.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOPT010

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Received ※ 08 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 18 June 2022

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WEPOPT011

Modelling FCC-ee Using MADX

1854

L. van Riesen-Haupt, H. Burkhardt, T.H.B. Persson, R. Tomás García
CERN, Meyrin, Switzerland

We present the latest developments for simulating FCC-ee using CERN’s MADX software. Along with updated benchmark studies, we describe how the latest MADX updates can facilitate the simulation of FCC-ee design features, including improvements in tapering and different options for implementing a tilted solenoid.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOPT011

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Received ※ 08 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 08 July 2022

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WEPOPT012

MAD-X for Future Accelerators

1858

T.H.B. Persson, H. Burkhardt, R. De Maria, L. Deniau, E.J. Høydalsvik, A. Latina, P.K. Skowroński, R. Tomás García, L. van Riesen-Haupt
CERN, Meyrin, Switzerland

The development of MAD-X was started more than 20 years ago and it still remains the main tool for single particle dynamics for both optics design, error studies as well as for operational model-based software at CERN. In this article, we outline some of the recent development of MAD-X and plans for the future. In particular, we focus on the development of the twiss module used to calculate optics functions in MAD-X which is based on first and second order matrices. These have traditionally been calculated as an expansion around the ideal orbit. In this paper, we describe explicitly how an expansion around the closed orbit can be employed instead, in order to get more precise results. We also describe the latest development of the beam-beam long range wire compensator in MAD-X, an element that has been implemented using the aforementioned approach.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOPT012

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Received ※ 08 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 23 June 2022 — Issue date ※ 01 July 2022

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WEPOPT059

Corrections of Systematic Normal Decapole Field Errors in the HL-LHC Separation/Recombination Dipoles

1991

J. Dilly, M. Giovannozzi, R. Tomás García, F.F. Van der Veken
CERN, Meyrin, Switzerland

Funding: This work has been supported by the HiLumi Project and been sponsored by the Wolfgang Gentner Programme of the German Federal Ministry of Education and Re-search.
Magnetic measurements revealed that the normal decapole (b5) errors of the recombination dipoles (D2) could have a systematic component of up to 11 units. Based on previous studies, it was predicted that the current corrections would not be able to compensate this, thereby leading to a degradation of the dynamic aperture by about 0.5 - 1 ’. On the other hand, the separation dipole D1 is expected to have a systematic b5 component of 6-7 units and its contribution to the resonance driving terms will partly compensate the effect of D2, due to the opposite field strength of the main component. Simulations were performed with the HL-LHC V1.4 lattice to test these concerns and to verify the compensation assumption. In addition, various normal decapole resonance driving terms were examined for correction, the results of which are presented in this contribution.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOPT059

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Received ※ 07 June 2022 — Revised ※ 15 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 03 July 2022

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WEPOPT060

Controlling Landau Damping via Feed-Down From High-Order Correctors in the LHC and HL-LHC

1995

SUSPMF005

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

J. Dilly, E.H. Maclean, R. Tomás García
CERN, Meyrin, Switzerland

Funding: This work has been supported by the HiLumi Project and been sponsored by the Wolfgang Gentner Programme of the German Federal Ministry of Education and Re-search.
Amplitude detuning measurements in the LHC have shown that a significant amount of detuning is generated in Beam 1 via feed-down from decapole and dodecapole field errors in the triplets of the experiment insertion regions, while in Beam 2 this detuning is negligible. In this study, we investigate the cause of this behavior and we attempt to find corrections that use the feed-down from the nonlinear correctors in the insertion region for amplitude detuning.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOPT060

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Received ※ 07 June 2022 — Revised ※ 15 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 06 July 2022

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WEPOPT061

A Flexible Nonlinear Resonance Driving Term Based Correction Algorithm with Feed-Down

1999

J. Dilly, R. Tomás García
CERN, Meyrin, Switzerland

Funding: This work has been supported by the HiLumi Project and been sponsored by the Wolfgang Gentner Programme of the German Federal Ministry of Education and Re-search.
The optics in the insertion regions of the LHC and its upgrade project the High Luminosity LHC are very sensitive to local magnetic errors, due to the extremely high beta-functions. In collision optics, the non-zero closed orbit in the same region leads to a "feed-down" of high-order errors to lower orders, causing additional effects detrimental to beam lifetime. An extension to the well-established method for correcting these errors by locally suppressing resonance driving terms has been undertaken, not only taking this feed-down into account, but also adding the possibility of utilizing it such that the powering of higher-order correctors will compensate for lower order errors. Existing correction schemes have also operated on the assumption of (anti-)symmetric beta-functions of the optics in the two rings. This assumption can fail for a multitude of reasons, such as inherently asymmetric optics and unevenly distributed errors. In this respect, an extension of this correction scheme has been developed, removing the need for symmetry by operating on the two separate optics of the beams simultaneously.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOPT061

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Received ※ 07 June 2022 — Accepted ※ 14 June 2022 — Issue date ※ 15 June 2022

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