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Chapter 28: Non-linear Optics Measurements and Corrections
/ Maclean, E H (CERN) ; Carlier, F (CERN) ; Dilly, J W (CERN) ; Giovannozzi, M (CERN) ; Karastathis, N ; Persson, T H B (CERN) ; Tomás, R (CERN)
Nonlinear optics errors in low-β* insertions pose a serious challenge to successful operation of the HL-LHC. LHC experience however has demonstrated that the previously assumed correction strategy, based upon ideal compensation of selected nonlinear resonances, as determined from magnetic measurements, suffers from several limitations. [...]
2024 - 14 p.
- Published in : Adv. Ser. Direct. High Energy Phys. 31 (2024) 579-592
Fulltext: PDF;
In : The High Luminosity Large Hadron Collider, pp.579-592
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Optics for Landau damping with minimized octupolar resonances in the LHC
/ Tomás, R (CERN) ; Carlier, F (CERN) ; Chudoba, F (CERN) ; Deniau, L (CERN) ; Dilly, J (CERN) ; Ferrentino, V (CERN ; Naples U.) ; Horney, S (CERN) ; Hostettler, M (CERN) ; Keintzel, J (CERN) ; Kostoglou, S (CERN) et al.
Operation of the Large Hadron Collider (LHC) requires strongoctupolar magnetic fields to suppress coherent beam instabilities.The amplitude detuning that is generated by these octupolar magneticfields brings the tune of individual particles close to harmfulresonances, which are mostly driven by the octupolar fieldsthemselves. In 2023, new optics were deployed in the LHC atinjection with optimized betatronic phase advances to minimize theresonances from the octupolar fields without affecting the amplitudedetuning. [...]
2024 - 14 p.
- Published in : JINST 19 (2024) T05010
Fulltext: PDF;
In : 68th ICFA Advanced Beam Dynamics workshop on high-Intensity and High-Brightness Hadron Beams (HB 2023), CERN, Geneva, Switzerland, 9 - 13 Oct 2023, pp.T05010
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Mitigation of losses at injection protection devices in the CERN LHC
/ Tomás, R (CERN) ; Calia, A (CERN) ; D'Andrea, M (CERN) ; Deniau, L (CERN) ; Jacquet, D (CERN) ; Kostoglou, S (CERN) ; Maclean, E H (CERN) ; Mirarchi, D (CERN) ; Paraschou, K (CERN) ; Persson, T (CERN) et al.
During loss maps performed with beam at injection energy in the LHC with the high octupole and chromaticity settings used for multi-train operation, large beam losses were observed at an injection protection device (TDIS). Although these losses did not present a threat to machine operation or protection, reducing them is of high importance to improve machine performance. [...]
2023 - 4 p.
- Published in : JACoW IPAC 2023 (2023) MOPL019
Fulltext: PDF;
In : 14th International Particle Accelerator Conference (IPAC 2023), Venice, Italy, 7 - 12 May 2023, pp.MOPL019
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LHC Run 3 optics corrections
/ Carlier, F (CERN) ; Ojeda, A Costa (CERN) ; De Maria, R (CERN) ; Dilly, J (CERN) ; Ferrentino, V (CERN) ; Fol, E (CERN) ; Hofer, M (CERN) ; Keintzel, J (CERN) ; Le Garrec, M (CERN) ; Maclean, E H (CERN) et al.
The first year of Run 3 of the Large Hadron Collider (LHC) revealed significant changes in both linear and nonlinear optics errors with respect to Run 2. Several iterations of optics corrections were required to successfully bring the linear optics within operational tolerances. [...]
2023 - 4 p.
- Published in : JACoW IPAC 2023 (2023) MOPL015
Fulltext: PDF;
In : 14th International Particle Accelerator Conference (IPAC 2023), Venice, Italy, 7 - 12 May 2023, pp.MOPL015
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Challenges of K-modulation measurements in the LHC Run 3
/ Carlier, F (CERN) ; Ojeda, A Costa (CERN) ; Dilly, J (CERN) ; Ferrentino, V (CERN) ; Fol, E (CERN) ; Hofer, M (CERN) ; Keintzel, J (CERN) ; Le Garrec, M (CERN) ; Levens, T (CERN) ; Maclean, E H (CERN) et al.
The future upgrade to the High-Luminosity Large Hadron Collider (HL-LHC) will impose tight tolerances on IP optics measurements. k-modulation is currently the preferred method in the LHC for IP optics measurements and will play a critical role in the HL-LHC. [...]
2023 - 4 p.
- Published in : JACoW IPAC 2023 (2023) MOPL014
Fulltext: PDF;
In : 14th International Particle Accelerator Conference (IPAC 2023), Venice, Italy, 7 - 12 May 2023, pp.MOPL014
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Measurement and modelling of decapole errors in the LHC from beam-based studies
/ Le Garrec, M (Goethe U., Frankfurt (main) ; CERN) ; Carlier, F S (CERN) ; Dilly, J (CERN) ; Ferrentino, V (CERN) ; Maclean, E H (CERN) ; Paraschou, K (CERN) ; Tomás, R (CERN)
Studies of third-order chromaticity in the LHC during its initial two runs have consistently demonstrated a substantial discrepancy between the expected Q''' at injection and that observed in beam-based measurements. In 2022 during Run 3, for the first time, studies of Q''' have been complemented by measurements of chromatic detuning, being the momentum-dependence of amplitude detuning, and the decapole resonance driving term 𝑓1004. [...]
2023 - 4 p.
- Published in : JACoW IPAC 2023 (2023) MOPL024
Fulltext: PDF;
In : 14th International Particle Accelerator Conference (IPAC 2023), Venice, Italy, 7 - 12 May 2023, pp.MOPL024
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First measurement of fourth and fifth order chromaticity in the LHC
/ Le Garrec, M (Goethe U., Frankfurt (main) ; CERN) ; Carlier, F S (CERN) ; Dilly, J (CERN) ; Maclean, E H (CERN) ; Persson, T H B (CERN) ; Tomás, R (CERN) ; Wegscheider, A (CERN)
Chromaticity up to the third order in the LHC has been well observed in the LHC’s first and second operational runs, with regular beam-based measurements performed during commissioning and machine development. In previous runs however, no higher-order chromaticity could be observed. [...]
2023 - 4 p.
- Published in : JACoW IPAC 2023 (2023) MOPL027
Fulltext: PDF;
In : 14th International Particle Accelerator Conference (IPAC 2023), Venice, Italy, 7 - 12 May 2023, pp.MOPL027
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First operational dodecapole correction in the LHC
/ Dilly, J (CERN ; Humboldt U., Berlin (main)) ; Ferrentino, V (CERN ; Naples U.) ; Le Garrec, M (CERN ; Goethe U., Frankfurt (main)) ; Maclean, E H (CERN) ; Malina, L (DESY) ; Persson, T (CERN) ; Pugnat, T (CERN) ; van Riesen-Haupt, L (LPHE, Lausanne) ; Soubelet, F (CERN ; U. Liverpool (main)) ; Tomás, R (CERN)
Amplitude detuning measurements in the LHC have shown that a significant amount of detuning is generated via feed-down from high-order field errors in the magnets of the experiment insertion regions. This undesired effect can be detrimental to the luminosity production of the machine and is expected to be enhanced in the upcoming high-luminosity upgrade of the collider, the HL-LHC. [...]
2023 - 22 p.
- Published in : Phys. Rev. Accel. Beams 26 (2023) 121001
Fulltext: PDF;
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