IPAC2022 - List of Authors (Hofer, M.)

Paper	Title	Page
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)

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)

WEPOST011	Studies on Top-Up Injection into the FCC-ee Collider Ring	1699
SUSPMF006	use link to see paper's listing under its alternate paper code
	P.J. Hunchak, M.J. Boland CLS, Saskatoon, Saskatchewan, Canada M. Aiba PSI, Villigen PSI, Switzerland W. Bartmann, Y. Dutheil, M. Hofer, R.L. Ramjiawan, F. Zimmermann CERN, Meyrin, Switzerland M.J. Boland University of Saskatchewan, Saskatoon, Canada
	In order to maximize the luminosity production time in the FCC-ee, top-up injection will be employed. The positron and electron beams will be accelerated to the collision energy in the booster ring before being injected with either a small transverse or longitudinal separation to the stored beam. Using this scheme essentially keeps the beam current constant and, apart from a brief period during the injection process, collision data can be continuously acquired. Two top-up injection schemes, each with on- and off-momentum sub-schemes, viable for FCC-ee have been identified in the past and are studied in further detail to find a suitable design for each of the four operation modes of the FCC-ee. In this paper, injection straight optics, initial injection tracking studies and the effect on the stored beam are presented. Additionally, a basic proxy error lattice is introduced as a first step to studying injection into an imperfect machine.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOST011
About •	Received ※ 08 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 19 June 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPOST016	Development of Collimation Simulations for the FCC-ee	1718
	A. Abramov, R. Bruce, M. Hofer, G. Iadarola, S. Redaelli CERN, Meyrin, Switzerland F.S. Carlier, T. Pieloni, M. Rakic EPFL, Lausanne, Switzerland L.J. Nevay JAI, Egham, Surrey, United Kingdom S.M. White ESRF, Grenoble, France
	A collimation system is under study for the FCC-ee to protect the machine from the multi-MJ electron and positron beams and limit the backgrounds to the detectors. One of the key aspects of the collimation system design is the setup of simulation studies combining particle tracking and scattering in the collimators. The tracking must include effects important for electron beam single-particle dynamics in the FCC-ee, such as synchrotron radiation. For collimation, an aperture model and particle-matter interactions for electrons are required. There are currently no established simulation frameworks that include all the required features. The latest developments of an integrated framework for multi-turn collimation studies in the FCC-ee are presented. The framework is based on an interface between tracking codes, pyAT and Xtrack, and a particle-matter interaction code, BDSIM, based on Geant4. Promising alternative simulation codes and frameworks are also discussed. The challenges are outlined, and the first results are presented, including preliminary loss maps for the FCC-ee.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOST016
About •	Received ※ 07 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 29 June 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPOST017	Design of a Collimation Section for the FCC-ee	1722
	M. Hofer, A. Abramov, R. Bruce, K. Oide, F. Zimmermann CERN, Meyrin, Switzerland M. Moudgalya, T. Pieloni EPFL, Lausanne, Switzerland K. Oide KEK, Ibaraki, Japan
	The design parameters of the FCC-ee foresee operation with a total stored beam energy of about 20 MJ, exceeding those of previous lepton colliders by almost two orders of magnitude. Given the inherent damage potential, a halo collimation system is studied to protect the machine hardware, in particular superconducting equipment such as the final focus quadrupoles, from sudden beam loss. The different constraints that led to dedicating one straight section to collimation will be outlined. In addition, a preliminary layout and optics for a collimation insertion are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOST017
About •	Received ※ 07 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 25 June 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

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

WEPOTK025	Concepts and Considerations for FCC-ee Top-Up Injection Strategies	2106
	R.L. Ramjiawan, W. Bartmann, Y. Dutheil, M. Hofer CERN, Meyrin, Switzerland M. Aiba PSI, Villigen PSI, Switzerland P.J. Hunchak University of Saskatchewan, Saskatoon, Canada P.J. Hunchak CLS, Saskatoon, Saskatchewan, Canada
	The Future Circular electron-positron Collider (FCC-ee) is proposed to operate in four modes, with beam energies from 45.6 GeV (Z-pole) to 182.5 GeV (tt-bar production) and luminosities up to 4.6×10³⁶ cm²s^-1. At the highest energies the beam lifetime would be less than one hour, meaning that top-up injection will be crucial to maximise the integrated luminosity. Two top-up injection strategies are considered here: conventional injection, employing a closed orbit bump and septum, and multipole-kicker injection, with a pulsed multipole magnet and septum. On-axis and off-axis injections are considered for both. We present a comparison of these injection strategies taking into account aspects such as spatial constraints, machine protection, disturbance to the stored beam and injection efficiency. We overview potential kicker and septum technologies for each.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOTK025
About •	Received ※ 03 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 14 June 2022 — Issue date ※ 14 June 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

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)

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)

WEPOST011

Studies on Top-Up Injection into the FCC-ee Collider Ring

1699

SUSPMF006

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

P.J. Hunchak, M.J. Boland
CLS, Saskatoon, Saskatchewan, Canada
M. Aiba
PSI, Villigen PSI, Switzerland
W. Bartmann, Y. Dutheil, M. Hofer, R.L. Ramjiawan, F. Zimmermann
CERN, Meyrin, Switzerland
M.J. Boland
University of Saskatchewan, Saskatoon, Canada

In order to maximize the luminosity production time in the FCC-ee, top-up injection will be employed. The positron and electron beams will be accelerated to the collision energy in the booster ring before being injected with either a small transverse or longitudinal separation to the stored beam. Using this scheme essentially keeps the beam current constant and, apart from a brief period during the injection process, collision data can be continuously acquired. Two top-up injection schemes, each with on- and off-momentum sub-schemes, viable for FCC-ee have been identified in the past and are studied in further detail to find a suitable design for each of the four operation modes of the FCC-ee. In this paper, injection straight optics, initial injection tracking studies and the effect on the stored beam are presented. Additionally, a basic proxy error lattice is introduced as a first step to studying injection into an imperfect machine.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOST011

About •

Received ※ 08 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 19 June 2022

Cite •

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

WEPOST016

Development of Collimation Simulations for the FCC-ee

1718

A. Abramov, R. Bruce, M. Hofer, G. Iadarola, S. Redaelli
CERN, Meyrin, Switzerland
F.S. Carlier, T. Pieloni, M. Rakic
EPFL, Lausanne, Switzerland
L.J. Nevay
JAI, Egham, Surrey, United Kingdom
S.M. White
ESRF, Grenoble, France

A collimation system is under study for the FCC-ee to protect the machine from the multi-MJ electron and positron beams and limit the backgrounds to the detectors. One of the key aspects of the collimation system design is the setup of simulation studies combining particle tracking and scattering in the collimators. The tracking must include effects important for electron beam single-particle dynamics in the FCC-ee, such as synchrotron radiation. For collimation, an aperture model and particle-matter interactions for electrons are required. There are currently no established simulation frameworks that include all the required features. The latest developments of an integrated framework for multi-turn collimation studies in the FCC-ee are presented. The framework is based on an interface between tracking codes, pyAT and Xtrack, and a particle-matter interaction code, BDSIM, based on Geant4. Promising alternative simulation codes and frameworks are also discussed. The challenges are outlined, and the first results are presented, including preliminary loss maps for the FCC-ee.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOST016

About •

Received ※ 07 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 29 June 2022

Cite •

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

WEPOST017

Design of a Collimation Section for the FCC-ee

1722

M. Hofer, A. Abramov, R. Bruce, K. Oide, F. Zimmermann
CERN, Meyrin, Switzerland
M. Moudgalya, T. Pieloni
EPFL, Lausanne, Switzerland
K. Oide
KEK, Ibaraki, Japan

The design parameters of the FCC-ee foresee operation with a total stored beam energy of about 20 MJ, exceeding those of previous lepton colliders by almost two orders of magnitude. Given the inherent damage potential, a halo collimation system is studied to protect the machine hardware, in particular superconducting equipment such as the final focus quadrupoles, from sudden beam loss. The different constraints that led to dedicating one straight section to collimation will be outlined. In addition, a preliminary layout and optics for a collimation insertion are presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOST017

About •

Received ※ 07 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 25 June 2022

Cite •

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

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

Cite •

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

WEPOTK025

Concepts and Considerations for FCC-ee Top-Up Injection Strategies

2106

R.L. Ramjiawan, W. Bartmann, Y. Dutheil, M. Hofer
CERN, Meyrin, Switzerland
M. Aiba
PSI, Villigen PSI, Switzerland
P.J. Hunchak
University of Saskatchewan, Saskatoon, Canada
P.J. Hunchak
CLS, Saskatoon, Saskatchewan, Canada

The Future Circular electron-positron Collider (FCC-ee) is proposed to operate in four modes, with beam energies from 45.6 GeV (Z-pole) to 182.5 GeV (tt-bar production) and luminosities up to 4.6×10³⁶ cm²s^-1. At the highest energies the beam lifetime would be less than one hour, meaning that top-up injection will be crucial to maximise the integrated luminosity. Two top-up injection strategies are considered here: conventional injection, employing a closed orbit bump and septum, and multipole-kicker injection, with a pulsed multipole magnet and septum. On-axis and off-axis injections are considered for both. We present a comparison of these injection strategies taking into account aspects such as spatial constraints, machine protection, disturbance to the stored beam and injection efficiency. We overview potential kicker and septum technologies for each.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOTK025

About •

Received ※ 03 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 14 June 2022 — Issue date ※ 14 June 2022

Cite •

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