HB2023 - List of Authors (Persson, T.H.B.)

Paper	Title	Page
TUC4C2	Mitigating Collimation Impedance and Improving Halo Cleaning with New Optics and Settings Strategy of the HL-LHC Betatron Collimation System	183
	B. Lindström, R. Bruce, X. Buffat, R. De Maria, L. Giacomel, P.D. Hermes, D. Mirarchi, N. Mounet, T.H.B. Persson, S. Redaelli, R. Tomás García, F.F. Van der Veken, A. Wegscheider CERN, Meyrin, Switzerland
	Funding: Work supported by the HL-LHC project With High Luminosity Large Hadron Collider (HL-LHC) beam intensities, there are concerns that the beam losses in the dispersion suppressors around the betatron cleaning insertion might exceed the quench limits. Furthermore, to maximize the beam lifetime it is important to reduce the impedance as much as possible. The collimators constitute one of the main sources of impedance in HL-LHC, given the need to operate with small collimator gaps. To improve this, a new optics was developed which increases the beta function in the collimation area, as well as the single pass dispersion from the primary collimators to the downstream shower absorbers. Other possible improvements from orbit bumps, to further enhance the locally generated dispersion, and from asymmetric collimator settings were also studied. The new solutions were partially tested with 6.8 TeV beams at the LHC in a dedicated machine experiment in 2022. In this paper, the new performance is reviewed and prospects for future operational deployment are discussed.
	Slides TUC4C2 [2.222 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-HB2023-TUC4C2
About •	Received ※ 01 October 2023 — Revised ※ 08 October 2023 — Accepted ※ 11 October 2023 — Issued ※ 28 October 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THBP14	LHC Optics Measurements from Transverse Damper for the High Intensity Frontier	479
	T. Nissinen, F.S. Carlier, M. Le Garrec, E.H. Maclean, T.H.B. Persson, R. Tomás García, A. Wegscheider CERN, Meyrin, Switzerland
	Current and future accelerator projects are pushing the brightness and intensity frontier, creating new challenges for turn-by-turn based optics measurements. Transverse oscillations are limited in amplitude due to particle losses. The LHC Transverse Damper (ADT) is capable of generating low amplitude ac-dipole like transverse coherent beam oscillations. While the amplitude of such excitations is low, it is compensated by the excitation length of the ADT which, in theory, can last for up to 48h. Using the ADT, it is possible to use the maximum BPM acquisition length and improve the spectral resolution. First optics measurements have been performed using the ADT in the LHC in 2023, and the results are presented in this paper. Furthermore, some observed limitations of this method are presented and their impact on ADT studies are discussed.
	Poster THBP14 [2.632 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP14
About •	Received ※ 01 October 2023 — Revised ※ 08 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 25 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)

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)

Paper

Title

Page

Mitigating Collimation Impedance and Improving Halo Cleaning with New Optics and Settings Strategy of the HL-LHC Betatron Collimation System

183

B. Lindström, R. Bruce, X. Buffat, R. De Maria, L. Giacomel, P.D. Hermes, D. Mirarchi, N. Mounet, T.H.B. Persson, S. Redaelli, R. Tomás García, F.F. Van der Veken, A. Wegscheider
CERN, Meyrin, Switzerland

Funding: Work supported by the HL-LHC project
With High Luminosity Large Hadron Collider (HL-LHC) beam intensities, there are concerns that the beam losses in the dispersion suppressors around the betatron cleaning insertion might exceed the quench limits. Furthermore, to maximize the beam lifetime it is important to reduce the impedance as much as possible. The collimators constitute one of the main sources of impedance in HL-LHC, given the need to operate with small collimator gaps. To improve this, a new optics was developed which increases the beta function in the collimation area, as well as the single pass dispersion from the primary collimators to the downstream shower absorbers. Other possible improvements from orbit bumps, to further enhance the locally generated dispersion, and from asymmetric collimator settings were also studied. The new solutions were partially tested with 6.8 TeV beams at the LHC in a dedicated machine experiment in 2022. In this paper, the new performance is reviewed and prospects for future operational deployment are discussed.

Slides TUC4C2 [2.222 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-TUC4C2

About •

Received ※ 01 October 2023 — Revised ※ 08 October 2023 — Accepted ※ 11 October 2023 — Issued ※ 28 October 2023

Cite •

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

THBP14

LHC Optics Measurements from Transverse Damper for the High Intensity Frontier

479

T. Nissinen, F.S. Carlier, M. Le Garrec, E.H. Maclean, T.H.B. Persson, R. Tomás García, A. Wegscheider
CERN, Meyrin, Switzerland

Current and future accelerator projects are pushing the brightness and intensity frontier, creating new challenges for turn-by-turn based optics measurements. Transverse oscillations are limited in amplitude due to particle losses. The LHC Transverse Damper (ADT) is capable of generating low amplitude ac-dipole like transverse coherent beam oscillations. While the amplitude of such excitations is low, it is compensated by the excitation length of the ADT which, in theory, can last for up to 48h. Using the ADT, it is possible to use the maximum BPM acquisition length and improve the spectral resolution. First optics measurements have been performed using the ADT in the LHC in 2023, and the results are presented in this paper. Furthermore, some observed limitations of this method are presented and their impact on ADT studies are discussed.

Poster THBP14 [2.632 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP14

About •

Received ※ 01 October 2023 — Revised ※ 08 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 25 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)

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)