HB2023 - List of Authors (Paraschou, K.)

Paper	Title	Page
MOA1I1	Beam Performance with the LHC Injectors Upgrade	1
	G. Rumolo, S.C.P. Albright, R. Alemany-Fernández, M.E. Angoletta, C. Antuono, T. Argyropoulos, F. Asvesta, M.J. Barnes, H. Bartosik, P. Baudrenghien, G. Bellodi, N. Biancacci, C. Bracco, N. Bruchon, E. Carlier, J. Coupard, H. Damerau, G.P. Di Giovanni, A. Findlay, M.A. Fraser, A. Funken, R. Garoby, S.S. Gilardoni, B. Goddard, G. Hagmann, K. Hanke, A. Huschauer, G. Iadarola, V. Kain, I. Karpov, J.-B. Lallement, A. Lasheen, T.E. Levens, K.S.B. Li, A.M. Lombardi, E.H. Maclean, D. Manglunki, I. Mases Solé, M. Meddahi, L. Mether, B. Mikulec, E. Montesinos, Y. Papaphilippou, G. Papotti, K. Paraschou, C. Pasquino, F. Pedrosa, T. Prebibaj, S. Prodon, D. Quartullo, F. Roncarolo, B. Salvant, M. Schenk, R. Scrivens, E.N. Shaposhnikova, L. Sito, P.K. Skowroński, A. Spierer, R. Steerenberg, M. Sullivan, F.M. Velotti, R. Veness, C. Vollinger, R. Wegner, C. Zannini, E. de la Fuente CERN, Meyrin, Switzerland T. Prebibaj IAP, Frankfurt am Main, Germany
	The LHC Injectors Upgrade (LIU) project was put in place between 2010 and 2021 to increase the intensity and brightness in the LHC injectors to match the challenging requirements of the High-Luminosity LHC (HL-LHC) project, while ensuring reliable operation of the injectors complex up to the end of the HL-LHC era (ca. 2040). During the 2019-2020 CERN accelerators shutdown, extensive hardware modifications were implemented in the entire LHC proton and ion injection chains, involving the new Linac4, the Proton Synchrotron Booster (PSB), the Proton Synchrotron (PS), the Super Proton Synchrotron (SPS) and the ion PS injectors, i.e. the Linac3 and the Low Energy Ion Ring (LEIR). Since 2021, beams have been recommissioned throughout the injectors’ chain and the beam parameters are being gradually ramped up to meet the LIU specifications using new beam dynamics solutions adapted to the upgraded accelerators. This paper focuses on the proton beams and describes the current state of the art.
	Slides MOA1I1 [10.002 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-HB2023-MOA1I1
About •	Received ※ 29 September 2023 — Revised ※ 05 October 2023 — Accepted ※ 09 October 2023 — Issued ※ 18 October 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUA2I1	Xsuite: An Integrated Beam Physics Simulation Framework	73
	G. Iadarola, A. Abramov, X. Buffat, R. De Maria, D. Demetriadou, L. Deniau, P.D. Hermes, P. Kicsiny, P.M. Kruyt, A. Latina, S. Łopaciuk, L. Mether, K. Paraschou, T. Pieloni, G. Sterbini, F.F. Van der Veken CERN, Meyrin, Switzerland P. Belanger UBC & TRIUMF, Vancouver, British Columbia, Canada D. Di Croce, M. Seidel, L. van Riesen-Haupt EPFL, Lausanne, Switzerland P.J. Niedermayer GSI, Darmstadt, Germany
	Xsuite is a newly developed modular simulation package combining in a single flexible and modern framework the capabilities of different tools developed at CERN in the past decades, notably Sixtrack, Sixtracklib, COMBI and PyHEADTAIL. The suite is made of a set of python modules (Xobjects, Xparts, Xtrack, Xcoll, Xfields, Xdpes) that can be flexibly combined together and with other accelerator-specific and general-purpose python tools to study complex simulation scenarios. The code allows for symplectic modeling of the particle dynamics, combined with the effect of synchrotron radiation, impedances, feedbacks, space charge, electron cloud, beam-beam, beamstrahlung, electron lenses. For collimation studies, beam-matter interaction is simulated using the K2 scattering model or interfacing Xsuite with the BDSIM/Geant4 library. Tools are available to compute the accelerator optics functions from the tracking model and to generate particle distributions matched to the optics. Different computing platforms are supported, including conventional CPUs, as well as GPUs from different vendors.
	Slides TUA2I1 [4.388 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-HB2023-TUA2I1
About •	Received ※ 30 September 2023 — Revised ※ 07 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 22 October 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEA1C1	Bunch-by-bunch Tune Shift Studies for LHC-type Beams in the CERN SPS	194
	I. Mases Solé, H. Bartosik, K. Paraschou, M. Schenk, C. Zannini CERN, Meyrin, Switzerland
	After the implementation of major upgrades as part of the LHC Injector Upgrade Project (LIU), the Super Proton Synchrotron (SPS) delivers high intensity bunch trains with 25 ns bunch spacing to the Large Hadron Collider (LHC). These beams are exposed to several collective effects in the SPS, such as beam coupling impedance, space charge and electron cloud, leading to relatively large bunch-by-bunch coherent and incoherent tune shifts. Tune correction to the nominal values at injection is crucial to ensure beam stability and good beam transmission. Measurements of the bunch-by-bunch coherent tune shifts have been performed under different beam conditions. In this paper, we present the measurements of the bunch-by-bunch tune shift as function of bunch intensity for trains of 72 bunches. The experimental data are compared to multiparticle tracking simulations (including other beam variants such as 8b4e beam and hybrid beams) using the SPS impedance model.
	Slides WEA1C1 [2.613 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-HB2023-WEA1C1
About •	Received ※ 29 September 2023 — Revised ※ 08 October 2023 — Accepted ※ 09 October 2023 — Issued ※ 09 October 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THA1C1	High Intensity Beam Dynamics Challenges for HL-LHC	344
	N. Mounet, H. Bartosik, P. Baudrenghien, R. Bruce, X. Buffat, R. Calaga, R. De Maria, C.N. Droin, L. Giacomel, M. Giovannozzi, G. Iadarola, S. Kostoglou, B. Lindström, L. Mether, E. Métral, Y. Papaphilippou, K. Paraschou, S. Redaelli, G. Rumolo, B. Salvant, G. Sterbini, R. Tomás García CERN, Meyrin, Switzerland
	The High Luminosity (HL-LHC) project aims to increase the integrated luminosity of CERN’s Large Hadron Collider (LHC) by an order of magnitude compared to its initial design. This requires a large increase in bunch intensity and beam brightness compared to the first LHC runs, and hence poses serious collective-effects challenges, related in particular to electron cloud, instabilities from beam-coupling impedance, and beam-beam effects. Here we present the associated constraints and the proposed mitigation measures to achieve the baseline performance of the upgraded LHC machine. We also discuss the interplay of these mitigation measures with other aspects of the accelerator, such as the physical and dynamic aperture, machine protection, magnet imperfections, optics, and the collimation system.
	Slides THA1C1 [3.385 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-HB2023-THA1C1
About •	Received ※ 01 October 2023 — Revised ※ 10 October 2023 — Accepted ※ 12 October 2023 — Issued ※ 15 October 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THBP15	Optimizing Resonance Driving Terms Using MAD-NG Parametric Maps	483
	L. Deniau, S. Kostoglou, E.H. Maclean, K. Paraschou, T.H.B. Persson, R. Tomás García CERN, Meyrin, Switzerland
	In 2023, a review of the LHC octupolar resonance driving terms at injection was carried out, motivated by two observations: (i) unwanted losses during the injection process with strongly powered octupoles and (ii) an expected reduction in emittance growth from e-cloud effects in simulations with weaker octupolar resonances. The MAD-NG code was used to simultaneously optimise the main octupolar resonances: 4Qx, 4Qy, and 2Qx-2Qy by adjusting 16 quadrupole families and 16 octupole families, for a total of 32 parameters. These knobs were introduced as parameters in the transfer map, allowing the Jacobian required by the optimiser to be calculated in a single pass, saving 32 additional optics evaluations and avoiding finite difference approximations. Constraints on tunes, amplitude detuning and optics around the machine were also considered as part of the optimisation process. This paper reviews the parametric optimisation with MAD-NG and compares the results with MADX-PTC.
	Poster THBP15 [0.938 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP15
About •	Received ※ 02 October 2023 — Revised ※ 06 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 17 October 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THBP16	Emittance Growth From Electron Clouds Forming in the LHC Arc Quadrupoles	487
	K. Paraschou, H. Bartosik, L. Deniau, G. Iadarola, E.H. Maclean, L. Mether, Y. Papaphilippou, G. Rumolo, R. Tomás García CERN, Meyrin, Switzerland T. Pieloni, J.M.B. Potdevin EPFL, Lausanne, Switzerland
	Operation of the Large Hadron Collider with proton bunches spaced 25 ns apart favours the formation of electron clouds. In fact, a slow emittance growth is observed in proton bunches at injection energy (450 GeV), showing a bunch-by-bunch signature that is compatible with electron cloud effects. The study of these effects is particularly relevant in view of the planned HL-LHC upgrade, which relies on significantly increased beam intensity and brightness. Particle tracking simulations that take into account both electron cloud effects and the non-linear magnetic fields of the lattice suggest that the electron clouds forming in the arc quadrupoles are responsible for the observed degradation. In this work, the simulation results are studied to gain insight into the mechanism which drives the slow emittance growth. Finally, it is discussed how optimising the optics of the lattice can allow the mitigation of such effects.
	Poster THBP16 [3.432 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP16
About •	Received ※ 29 September 2023 — Revised ※ 06 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 11 October 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THBP20	Optics for Landau Damping with Minimized Octupolar Resonances in the LHC	503
	R. Tomás García, F.S. Carlier, L. Deniau, J. Dilly, J. Keintzel, S. Kostoglou, M. Le Garrec, E.H. Maclean, K. Paraschou, T.H.B. Persson, F. Soubelet, A. Wegscheider CERN, Meyrin, Switzerland
	Operation of the Large Hadron Collider (LHC) requires strong octupolar magnetic fields to suppress coherent beam instabilities. The amplitude detuning that is generated by these octupolar magnetic fields brings the tune of individual particles close to harmful resonances, which are mostly driven by the octupolar fields themselves. In 2023, new optics were deployed in the LHC at injection with optimized betatronic phase advances to minimize the resonances from the octupolar fields without affecting the amplitude detuning. This paper reports on the optics design, commissioning and the lifetime measurements performed to validate the optics.
DOI •	reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP20
About •	Received ※ 01 October 2023 — Revised ※ 07 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 23 October 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THBP31	Electron Cloud Effects in the CERN Accelerators in Run 3	538
	L. Mether, H. Bartosik, L. Giacomel, G. Iadarola, S. Johannesson, I. Mases Solé, K. Paraschou, G. Rumolo, L. Sabato, C. Zannini, E. de la Fuente CERN, Meyrin, Switzerland S. Johannesson EPFL, Lausanne, Switzerland
	Several of the machines in the CERN accelerator complex, in particular the Large Hadron Collider (LHC) and the Super Proton Synchrotron (SPS), are prone to the build-up of electron clouds. Electron cloud effects are observed especially when the machines are operated with a 25 ns bunch spacing, which has routinely been used in the LHC since the start of its second operational run in 2015. After the completion of the LHC Injectors Upgrade program during the latest long shutdown period, the machines are currently operated with unprecedented bunch intensity and beam brightness. With the increase in bunch intensity, electron cloud effects have become one of the main performance limitations, as predicted by simulation studies. In this contribution we present the experimental observations of electron cloud effects since 2021 and discuss their implications for the future operation of the complex.
DOI •	reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP31
About •	Received ※ 01 October 2023 — Revised ※ 06 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 23 October 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Beam Performance with the LHC Injectors Upgrade

1

G. Rumolo, S.C.P. Albright, R. Alemany-Fernández, M.E. Angoletta, C. Antuono, T. Argyropoulos, F. Asvesta, M.J. Barnes, H. Bartosik, P. Baudrenghien, G. Bellodi, N. Biancacci, C. Bracco, N. Bruchon, E. Carlier, J. Coupard, H. Damerau, G.P. Di Giovanni, A. Findlay, M.A. Fraser, A. Funken, R. Garoby, S.S. Gilardoni, B. Goddard, G. Hagmann, K. Hanke, A. Huschauer, G. Iadarola, V. Kain, I. Karpov, J.-B. Lallement, A. Lasheen, T.E. Levens, K.S.B. Li, A.M. Lombardi, E.H. Maclean, D. Manglunki, I. Mases Solé, M. Meddahi, L. Mether, B. Mikulec, E. Montesinos, Y. Papaphilippou, G. Papotti, K. Paraschou, C. Pasquino, F. Pedrosa, T. Prebibaj, S. Prodon, D. Quartullo, F. Roncarolo, B. Salvant, M. Schenk, R. Scrivens, E.N. Shaposhnikova, L. Sito, P.K. Skowroński, A. Spierer, R. Steerenberg, M. Sullivan, F.M. Velotti, R. Veness, C. Vollinger, R. Wegner, C. Zannini, E. de la Fuente
CERN, Meyrin, Switzerland
T. Prebibaj
IAP, Frankfurt am Main, Germany

The LHC Injectors Upgrade (LIU) project was put in place between 2010 and 2021 to increase the intensity and brightness in the LHC injectors to match the challenging requirements of the High-Luminosity LHC (HL-LHC) project, while ensuring reliable operation of the injectors complex up to the end of the HL-LHC era (ca. 2040). During the 2019-2020 CERN accelerators shutdown, extensive hardware modifications were implemented in the entire LHC proton and ion injection chains, involving the new Linac4, the Proton Synchrotron Booster (PSB), the Proton Synchrotron (PS), the Super Proton Synchrotron (SPS) and the ion PS injectors, i.e. the Linac3 and the Low Energy Ion Ring (LEIR). Since 2021, beams have been recommissioned throughout the injectors’ chain and the beam parameters are being gradually ramped up to meet the LIU specifications using new beam dynamics solutions adapted to the upgraded accelerators. This paper focuses on the proton beams and describes the current state of the art.

Slides MOA1I1 [10.002 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-MOA1I1

About •

Received ※ 29 September 2023 — Revised ※ 05 October 2023 — Accepted ※ 09 October 2023 — Issued ※ 18 October 2023

Cite •

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

TUA2I1

Xsuite: An Integrated Beam Physics Simulation Framework

73

G. Iadarola, A. Abramov, X. Buffat, R. De Maria, D. Demetriadou, L. Deniau, P.D. Hermes, P. Kicsiny, P.M. Kruyt, A. Latina, S. Łopaciuk, L. Mether, K. Paraschou, T. Pieloni, G. Sterbini, F.F. Van der Veken
CERN, Meyrin, Switzerland
P. Belanger
UBC & TRIUMF, Vancouver, British Columbia, Canada
D. Di Croce, M. Seidel, L. van Riesen-Haupt
EPFL, Lausanne, Switzerland
P.J. Niedermayer
GSI, Darmstadt, Germany

Xsuite is a newly developed modular simulation package combining in a single flexible and modern framework the capabilities of different tools developed at CERN in the past decades, notably Sixtrack, Sixtracklib, COMBI and PyHEADTAIL. The suite is made of a set of python modules (Xobjects, Xparts, Xtrack, Xcoll, Xfields, Xdpes) that can be flexibly combined together and with other accelerator-specific and general-purpose python tools to study complex simulation scenarios. The code allows for symplectic modeling of the particle dynamics, combined with the effect of synchrotron radiation, impedances, feedbacks, space charge, electron cloud, beam-beam, beamstrahlung, electron lenses. For collimation studies, beam-matter interaction is simulated using the K2 scattering model or interfacing Xsuite with the BDSIM/Geant4 library. Tools are available to compute the accelerator optics functions from the tracking model and to generate particle distributions matched to the optics. Different computing platforms are supported, including conventional CPUs, as well as GPUs from different vendors.

Slides TUA2I1 [4.388 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-TUA2I1

About •

Received ※ 30 September 2023 — Revised ※ 07 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 22 October 2023

Cite •

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

WEA1C1

Bunch-by-bunch Tune Shift Studies for LHC-type Beams in the CERN SPS

194

I. Mases Solé, H. Bartosik, K. Paraschou, M. Schenk, C. Zannini
CERN, Meyrin, Switzerland

After the implementation of major upgrades as part of the LHC Injector Upgrade Project (LIU), the Super Proton Synchrotron (SPS) delivers high intensity bunch trains with 25 ns bunch spacing to the Large Hadron Collider (LHC). These beams are exposed to several collective effects in the SPS, such as beam coupling impedance, space charge and electron cloud, leading to relatively large bunch-by-bunch coherent and incoherent tune shifts. Tune correction to the nominal values at injection is crucial to ensure beam stability and good beam transmission. Measurements of the bunch-by-bunch coherent tune shifts have been performed under different beam conditions. In this paper, we present the measurements of the bunch-by-bunch tune shift as function of bunch intensity for trains of 72 bunches. The experimental data are compared to multiparticle tracking simulations (including other beam variants such as 8b4e beam and hybrid beams) using the SPS impedance model.

Slides WEA1C1 [2.613 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-WEA1C1

About •

Received ※ 29 September 2023 — Revised ※ 08 October 2023 — Accepted ※ 09 October 2023 — Issued ※ 09 October 2023

Cite •

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

THA1C1

High Intensity Beam Dynamics Challenges for HL-LHC

344

N. Mounet, H. Bartosik, P. Baudrenghien, R. Bruce, X. Buffat, R. Calaga, R. De Maria, C.N. Droin, L. Giacomel, M. Giovannozzi, G. Iadarola, S. Kostoglou, B. Lindström, L. Mether, E. Métral, Y. Papaphilippou, K. Paraschou, S. Redaelli, G. Rumolo, B. Salvant, G. Sterbini, R. Tomás García
CERN, Meyrin, Switzerland

The High Luminosity (HL-LHC) project aims to increase the integrated luminosity of CERN’s Large Hadron Collider (LHC) by an order of magnitude compared to its initial design. This requires a large increase in bunch intensity and beam brightness compared to the first LHC runs, and hence poses serious collective-effects challenges, related in particular to electron cloud, instabilities from beam-coupling impedance, and beam-beam effects. Here we present the associated constraints and the proposed mitigation measures to achieve the baseline performance of the upgraded LHC machine. We also discuss the interplay of these mitigation measures with other aspects of the accelerator, such as the physical and dynamic aperture, machine protection, magnet imperfections, optics, and the collimation system.

Slides THA1C1 [3.385 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-THA1C1

About •

Received ※ 01 October 2023 — Revised ※ 10 October 2023 — Accepted ※ 12 October 2023 — Issued ※ 15 October 2023

Cite •

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

THBP15

Optimizing Resonance Driving Terms Using MAD-NG Parametric Maps

483

L. Deniau, S. Kostoglou, E.H. Maclean, K. Paraschou, T.H.B. Persson, R. Tomás García
CERN, Meyrin, Switzerland

In 2023, a review of the LHC octupolar resonance driving terms at injection was carried out, motivated by two observations: (i) unwanted losses during the injection process with strongly powered octupoles and (ii) an expected reduction in emittance growth from e-cloud effects in simulations with weaker octupolar resonances. The MAD-NG code was used to simultaneously optimise the main octupolar resonances: 4Qx, 4Qy, and 2Qx-2Qy by adjusting 16 quadrupole families and 16 octupole families, for a total of 32 parameters. These knobs were introduced as parameters in the transfer map, allowing the Jacobian required by the optimiser to be calculated in a single pass, saving 32 additional optics evaluations and avoiding finite difference approximations. Constraints on tunes, amplitude detuning and optics around the machine were also considered as part of the optimisation process. This paper reviews the parametric optimisation with MAD-NG and compares the results with MADX-PTC.

Poster THBP15 [0.938 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP15

About •

Received ※ 02 October 2023 — Revised ※ 06 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 17 October 2023

Cite •

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

THBP16

Emittance Growth From Electron Clouds Forming in the LHC Arc Quadrupoles

487

K. Paraschou, H. Bartosik, L. Deniau, G. Iadarola, E.H. Maclean, L. Mether, Y. Papaphilippou, G. Rumolo, R. Tomás García
CERN, Meyrin, Switzerland
T. Pieloni, J.M.B. Potdevin
EPFL, Lausanne, Switzerland

Operation of the Large Hadron Collider with proton bunches spaced 25 ns apart favours the formation of electron clouds. In fact, a slow emittance growth is observed in proton bunches at injection energy (450 GeV), showing a bunch-by-bunch signature that is compatible with electron cloud effects. The study of these effects is particularly relevant in view of the planned HL-LHC upgrade, which relies on significantly increased beam intensity and brightness. Particle tracking simulations that take into account both electron cloud effects and the non-linear magnetic fields of the lattice suggest that the electron clouds forming in the arc quadrupoles are responsible for the observed degradation. In this work, the simulation results are studied to gain insight into the mechanism which drives the slow emittance growth. Finally, it is discussed how optimising the optics of the lattice can allow the mitigation of such effects.

Poster THBP16 [3.432 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP16

About •

Received ※ 29 September 2023 — Revised ※ 06 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 11 October 2023

Cite •

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

THBP20

Optics for Landau Damping with Minimized Octupolar Resonances in the LHC

503

R. Tomás García, F.S. Carlier, L. Deniau, J. Dilly, J. Keintzel, S. Kostoglou, M. Le Garrec, E.H. Maclean, K. Paraschou, T.H.B. Persson, F. Soubelet, A. Wegscheider
CERN, Meyrin, Switzerland

Operation of the Large Hadron Collider (LHC) requires strong octupolar magnetic fields to suppress coherent beam instabilities. The amplitude detuning that is generated by these octupolar magnetic fields brings the tune of individual particles close to harmful resonances, which are mostly driven by the octupolar fields themselves. In 2023, new optics were deployed in the LHC at injection with optimized betatronic phase advances to minimize the resonances from the octupolar fields without affecting the amplitude detuning. This paper reports on the optics design, commissioning and the lifetime measurements performed to validate the optics.

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP20

About •

Received ※ 01 October 2023 — Revised ※ 07 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 23 October 2023

Cite •

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

THBP31

Electron Cloud Effects in the CERN Accelerators in Run 3

538

L. Mether, H. Bartosik, L. Giacomel, G. Iadarola, S. Johannesson, I. Mases Solé, K. Paraschou, G. Rumolo, L. Sabato, C. Zannini, E. de la Fuente
CERN, Meyrin, Switzerland
S. Johannesson
EPFL, Lausanne, Switzerland

Several of the machines in the CERN accelerator complex, in particular the Large Hadron Collider (LHC) and the Super Proton Synchrotron (SPS), are prone to the build-up of electron clouds. Electron cloud effects are observed especially when the machines are operated with a 25 ns bunch spacing, which has routinely been used in the LHC since the start of its second operational run in 2015. After the completion of the LHC Injectors Upgrade program during the latest long shutdown period, the machines are currently operated with unprecedented bunch intensity and beam brightness. With the increase in bunch intensity, electron cloud effects have become one of the main performance limitations, as predicted by simulation studies. In this contribution we present the experimental observations of electron cloud effects since 2021 and discuss their implications for the future operation of the complex.

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP31

About •

Received ※ 01 October 2023 — Revised ※ 06 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 23 October 2023

Cite •

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