IPAC2021 - List of Authors (Maclean, E.H.)

Paper	Title	Page
MOPAB028	Using Machine Learning to Improve Dynamic Aperture Estimates	134
	F.F. Van der Veken, M. Giovannozzi, E.H. Maclean CERN, Geneva, Switzerland C.E. Montanari Bologna University, Bologna, Italy G. Valentino University of Malta, Information and Communication Technology, Msida, Malta
	The dynamic aperture (DA) is an important concept in the study of nonlinear beam dynamics. Several analytical models used to describe the evolution of DA as a function of time, and to extrapolate to realistic time scales that would not be reachable otherwise due to computational limitations, have been successfully developed. Even though these models have been quite successful in the past, the fitting procedure is rather sensitive to several details. Machine Learning (ML) techniques, which have been around for decades and have matured into powerful tools ever since, carry the potential to address some of these challenges. In this paper, two applications of ML approaches are presented and discussed in detail. Firstly, ML has been used to efficiently detect outliers in the DA computations. Secondly, ML techniques have been applied to improve the fitting procedures of the DA models, thus improving their predictive power.
	Poster MOPAB028 [1.764 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB028
About •	paper received ※ 18 May 2021 paper accepted ※ 25 May 2021 issue date ※ 12 August 2021
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MOPAB258	Corrections of Non-Linear Field Errors with Asymmetric Optics in LHC and HL-LHC Insertion Regions	817
	J. Dilly, E.H. Maclean, R. Tomás García CERN, Geneva, Switzerland
	Funding: Research supported by the HL-LHC project, CERN and the german Federal Ministry of Education and Research. Existing correction schemes to locally suppress resonance driving terms in the error-sensitive high-beta regions of the LHC and HL-LHC have operated on the assumption of symmetric beta-functions of the optics in the two rings. As this assumption can fail for a multitude of reasons, such as inherently asymmetric optics and unevenly distributed errors, an extension of this correction scheme has been developed removing the need for symmetry by operating on the two separate optics of the beams at the same time. Presented here is the impact of this novel approach on dynamic aperture as an important measure of particle stability.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB258
About •	paper received ※ 10 May 2021 paper accepted ※ 23 July 2021 issue date ※ 16 August 2021
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPAB259	Corrections of Feed-Down of Non-Linear Field Errors in LHC and HL-LHC Insertion Regions	821
	J. Dilly, E.H. Maclean, R. Tomás García CERN, Geneva, Switzerland
	Funding: Research supported by the HL-LHC project, CERN and the german Federal Ministry of Education and Research. The optics in the insertion regions of the LHC and its upgrade project the High Luminosity LHC (HL-LHC) are very sensitive to local magnetic errors, due to the extremely high beta-functions present. 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 proven 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. The impact of these corrections on measures of particle stability, namely dynamic aperture and amplitude detuning are presented in this contribution.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB259
About •	paper received ※ 10 May 2021 paper accepted ※ 23 July 2021 issue date ※ 15 August 2021
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPAB026	Optics Measurements and Correction Plans for the HL-LHC	2656
	T.H.B. Persson, X. Buffat, F.S. Carlier, R. De Maria, J. Dilly, E. Fol, D. Gamba, H. Garcia Morales, A. García-Tabarés Valdivieso, M. Giovannozzi, M. Hofer, E.J. Høydalsvik, J. Keintzel, M. Le Garrec, E.H. Maclean, L. Malina, P.K. Skowroński, F. Soubelet, R. Tomás García, F.F. Van der Veken, A. Wegscheider, D.W. Wolf, L. van Riesen-Haupt CERN, Meyrin, Switzerland J.M. Coello de Portugal PSI, Villigen PSI, Switzerland
	The High Luminosity LHC (HL-LHC) will require stringent optics correction to operate safely and deliver the design luminosity to the experiments. In order to achieve this, several new methods for optics correction have been developed. In this article, we outline some of these methods and we describe the envisioned strategy of how to use them in order to reach the challenging requirements of the HL-LHC physics program.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB026
About •	paper received ※ 17 May 2021 paper accepted ※ 27 July 2021 issue date ※ 30 August 2021
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPAB027	Optics Correction Strategy for Run 3 of the LHC	2660
	T.H.B. Persson, R. De Maria, J. Dilly, E. Fol, H. Garcia Morales, M. Hofer, E.J. Høydalsvik, J. Keintzel, M. Le Garrec, E.H. Maclean, L. Malina, F. Soubelet, R. Tomás García, A. Wegscheider, D.W. Wolf, L. van Riesen-Haupt CERN, Meyrin, Switzerland J.F. Cardona UNAL, Bogota D.C, Colombia
	The Run 3 of the LHC will continue to provide new challenges for optics corrections. In order to succeed and go beyond what was achieved previously, several new methods to measure and correct the optics have been developed. In this article we describe these methods and outline the plans for the optics commissioning in 2022.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB027
About •	paper received ※ 17 May 2021 paper accepted ※ 12 July 2021 issue date ※ 11 August 2021
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPAB210	Beam Commissioning of the New 160 MeV H⁻ Injection System of the CERN PS Booster	3116
	E. Renner, S.C.P. Albright, F. Antoniou, F. Asvesta, H. Bartosik, C. Bracco, G.P. Di Giovanni, L.O. Jorat, E.H. Maclean, M. Meddahi, B. Mikulec, T. Prebibaj, G. Rumolo, P.K. Skowroński, W.J.M. Weterings CERN, Geneva, Switzerland
	A key component to meeting the brightness targets of the LHC Injectors Upgrade (LIU) project at CERN is the new 160 MeV H⁻ charge exchange injection system into the Proton Synchrotron Booster. This system has been in beam commissioning since December 2020, optimizing the beam production schemes for tailoring different beams to the respective user-defined brightness targets. In this paper, selected measurements from the beam commissioning period are presented, characterizing the system’s flexibility to produce the required wide range of transverse emittances. The discussion focuses on the essential optimization of the injection set-up to minimize space charge driven emittance blow-up and injection errors. The results are completed by selected comparisons with multi-particle simulation models of the injection process.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB210
About •	paper received ※ 19 May 2021 paper accepted ※ 19 July 2021 issue date ※ 29 August 2021
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAB168	Optics Measurement by Excitation of Betatron Oscillations in the CERN PSB	4078
	E.H. Maclean, F. Antoniou, F. Asvesta, H. Bartosik, C. Bracco, J. Dilly, E. Fol, H. Garcia Morales, M. Hofer, J. Keintzel, M. Le Garrec, T.E. Levens, L. Malina, T.H.B. Persson, T. Prebibaj, E. Renner, P.K. Skowroński, F. Soubelet, R. Tomás García, A. Wegscheider, L. van Riesen-Haupt CERN, Meyrin, Switzerland
	Optics measurement from analysis of turn-by-turn BPM data of betatron oscillations excited with a kicker magnet has been employed very successfully in many machines but faces particular challenges in the CERN PSB where BPM to BPM phase advances are sub-optimal for optics reconstruction. Experience using turn-by-turn oscillation data for linear optics measurements during PSB commissioning in2021 is presented, with implications for the prospect of such techniques in the PSB more generally.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB168
About •	paper received ※ 19 May 2021 paper accepted ※ 14 July 2021 issue date ※ 27 August 2021
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAB169	A Mechanism for Emittance Growth Based on Non-Linear Islands in LHC	4082
	E.H. Maclean, M. Giovannozzi, T.H.B. Persson, R. Tomás García CERN, Geneva, Switzerland
	Landau octupoles are used in the LHC to prevent coherent instabilities of the circulating beam. The reduction of their strength occurring during the energy ramp can transport particles in nonlinear islands to larger amplitude. This has the potential to lead to emittance growth and to beam-losses. Beam-based studies and simulations of emittance growth during Landau octupole ramps performed in the LHC are presented to explore this mechanism in more detail.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB169
About •	paper received ※ 18 May 2021 paper accepted ※ 14 July 2021 issue date ※ 14 August 2021
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Using Machine Learning to Improve Dynamic Aperture Estimates

134

F.F. Van der Veken, M. Giovannozzi, E.H. Maclean
CERN, Geneva, Switzerland
C.E. Montanari
Bologna University, Bologna, Italy
G. Valentino
University of Malta, Information and Communication Technology, Msida, Malta

The dynamic aperture (DA) is an important concept in the study of nonlinear beam dynamics. Several analytical models used to describe the evolution of DA as a function of time, and to extrapolate to realistic time scales that would not be reachable otherwise due to computational limitations, have been successfully developed. Even though these models have been quite successful in the past, the fitting procedure is rather sensitive to several details. Machine Learning (ML) techniques, which have been around for decades and have matured into powerful tools ever since, carry the potential to address some of these challenges. In this paper, two applications of ML approaches are presented and discussed in detail. Firstly, ML has been used to efficiently detect outliers in the DA computations. Secondly, ML techniques have been applied to improve the fitting procedures of the DA models, thus improving their predictive power.

Poster MOPAB028 [1.764 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB028

About •

paper received ※ 18 May 2021 paper accepted ※ 25 May 2021 issue date ※ 12 August 2021

Export •

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

MOPAB258

Corrections of Non-Linear Field Errors with Asymmetric Optics in LHC and HL-LHC Insertion Regions

817

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

Funding: Research supported by the HL-LHC project, CERN and the german Federal Ministry of Education and Research.
Existing correction schemes to locally suppress resonance driving terms in the error-sensitive high-beta regions of the LHC and HL-LHC have operated on the assumption of symmetric beta-functions of the optics in the two rings. As this assumption can fail for a multitude of reasons, such as inherently asymmetric optics and unevenly distributed errors, an extension of this correction scheme has been developed removing the need for symmetry by operating on the two separate optics of the beams at the same time. Presented here is the impact of this novel approach on dynamic aperture as an important measure of particle stability.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB258

About •

paper received ※ 10 May 2021 paper accepted ※ 23 July 2021 issue date ※ 16 August 2021

Export •

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

MOPAB259

Corrections of Feed-Down of Non-Linear Field Errors in LHC and HL-LHC Insertion Regions

821

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

Funding: Research supported by the HL-LHC project, CERN and the german Federal Ministry of Education and Research.
The optics in the insertion regions of the LHC and its upgrade project the High Luminosity LHC (HL-LHC) are very sensitive to local magnetic errors, due to the extremely high beta-functions present. 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 proven 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. The impact of these corrections on measures of particle stability, namely dynamic aperture and amplitude detuning are presented in this contribution.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB259

About •

paper received ※ 10 May 2021 paper accepted ※ 23 July 2021 issue date ※ 15 August 2021

Export •

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

WEPAB026

Optics Measurements and Correction Plans for the HL-LHC

2656

T.H.B. Persson, X. Buffat, F.S. Carlier, R. De Maria, J. Dilly, E. Fol, D. Gamba, H. Garcia Morales, A. García-Tabarés Valdivieso, M. Giovannozzi, M. Hofer, E.J. Høydalsvik, J. Keintzel, M. Le Garrec, E.H. Maclean, L. Malina, P.K. Skowroński, F. Soubelet, R. Tomás García, F.F. Van der Veken, A. Wegscheider, D.W. Wolf, L. van Riesen-Haupt
CERN, Meyrin, Switzerland
J.M. Coello de Portugal
PSI, Villigen PSI, Switzerland

The High Luminosity LHC (HL-LHC) will require stringent optics correction to operate safely and deliver the design luminosity to the experiments. In order to achieve this, several new methods for optics correction have been developed. In this article, we outline some of these methods and we describe the envisioned strategy of how to use them in order to reach the challenging requirements of the HL-LHC physics program.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB026

About •

paper received ※ 17 May 2021 paper accepted ※ 27 July 2021 issue date ※ 30 August 2021

Export •

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

WEPAB027

Optics Correction Strategy for Run 3 of the LHC

2660

T.H.B. Persson, R. De Maria, J. Dilly, E. Fol, H. Garcia Morales, M. Hofer, E.J. Høydalsvik, J. Keintzel, M. Le Garrec, E.H. Maclean, L. Malina, F. Soubelet, R. Tomás García, A. Wegscheider, D.W. Wolf, L. van Riesen-Haupt
CERN, Meyrin, Switzerland
J.F. Cardona
UNAL, Bogota D.C, Colombia

The Run 3 of the LHC will continue to provide new challenges for optics corrections. In order to succeed and go beyond what was achieved previously, several new methods to measure and correct the optics have been developed. In this article we describe these methods and outline the plans for the optics commissioning in 2022.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB027

About •

paper received ※ 17 May 2021 paper accepted ※ 12 July 2021 issue date ※ 11 August 2021

Export •

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

WEPAB210

Beam Commissioning of the New 160 MeV H⁻ Injection System of the CERN PS Booster

3116

E. Renner, S.C.P. Albright, F. Antoniou, F. Asvesta, H. Bartosik, C. Bracco, G.P. Di Giovanni, L.O. Jorat, E.H. Maclean, M. Meddahi, B. Mikulec, T. Prebibaj, G. Rumolo, P.K. Skowroński, W.J.M. Weterings
CERN, Geneva, Switzerland

A key component to meeting the brightness targets of the LHC Injectors Upgrade (LIU) project at CERN is the new 160 MeV H⁻ charge exchange injection system into the Proton Synchrotron Booster. This system has been in beam commissioning since December 2020, optimizing the beam production schemes for tailoring different beams to the respective user-defined brightness targets. In this paper, selected measurements from the beam commissioning period are presented, characterizing the system’s flexibility to produce the required wide range of transverse emittances. The discussion focuses on the essential optimization of the injection set-up to minimize space charge driven emittance blow-up and injection errors. The results are completed by selected comparisons with multi-particle simulation models of the injection process.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB210

About •

paper received ※ 19 May 2021 paper accepted ※ 19 July 2021 issue date ※ 29 August 2021

Export •

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

THPAB168

Optics Measurement by Excitation of Betatron Oscillations in the CERN PSB

4078

E.H. Maclean, F. Antoniou, F. Asvesta, H. Bartosik, C. Bracco, J. Dilly, E. Fol, H. Garcia Morales, M. Hofer, J. Keintzel, M. Le Garrec, T.E. Levens, L. Malina, T.H.B. Persson, T. Prebibaj, E. Renner, P.K. Skowroński, F. Soubelet, R. Tomás García, A. Wegscheider, L. van Riesen-Haupt
CERN, Meyrin, Switzerland

Optics measurement from analysis of turn-by-turn BPM data of betatron oscillations excited with a kicker magnet has been employed very successfully in many machines but faces particular challenges in the CERN PSB where BPM to BPM phase advances are sub-optimal for optics reconstruction. Experience using turn-by-turn oscillation data for linear optics measurements during PSB commissioning in2021 is presented, with implications for the prospect of such techniques in the PSB more generally.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB168

About •

paper received ※ 19 May 2021 paper accepted ※ 14 July 2021 issue date ※ 27 August 2021

Export •

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

THPAB169

A Mechanism for Emittance Growth Based on Non-Linear Islands in LHC

4082

E.H. Maclean, M. Giovannozzi, T.H.B. Persson, R. Tomás García
CERN, Geneva, Switzerland

Landau octupoles are used in the LHC to prevent coherent instabilities of the circulating beam. The reduction of their strength occurring during the energy ramp can transport particles in nonlinear islands to larger amplitude. This has the potential to lead to emittance growth and to beam-losses. Beam-based studies and simulations of emittance growth during Landau octupole ramps performed in the LHC are presented to explore this mechanism in more detail.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB169

About •

paper received ※ 18 May 2021 paper accepted ※ 14 July 2021 issue date ※ 14 August 2021

Export •

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