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Assessment of the real part of the impedance of the LHC collimators with instability growth rate measurements
/ Giacomel, Lorenzo (CERN) ; Lindstrom, Bjorn (CERN ; Royal Holloway, U. of London) ; Iadarola, Giovanni (CERN) ; Rumolo, Giovanni (CERN) ; Mounet, Nicolas (CERN) ; Bruce, Roderik (CERN) ; Buffat, Xavier (CERN)
The impedance of the Large Hadron Collider (LHC) is a source of instabilities and has to be monitored closely. It is usually assessed by measuring the tune-shift vs intensity, in particular at top energy where it is the most critical, as the collimators are the closest to the beam. [...]
2024 - 4 p.
- Published in : JACoW IPAC 2024 (2024) THPC57
Fulltext: PDF;
In : 15th International Particle Accelerator Conference (IPAC 2024), Nashville, TN, United States, 19 - 24 May 2024, pp.THPC57
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Refining the LHC Longitudinal Impedance Model
/ Zampetakis, Michail (CERN) ; Argyropoulos, Theodoros (CERN) ; Brischetto, Ylenia (CERN) ; Calaga, Rama (CERN) ; Giacomel, Lorenzo (CERN) ; Karlsen-Bæck, Birk Emil (INFN, Rome ; Rome U. ; CERN) ; Karpov, Ivan (CERN) ; Mounet, Nicolas (CERN) ; Salvant, Benoit (CERN) ; Timko, Helga (CERN)
Modelling the longitudinal impedance for the Large Hadron Collider (LHC) has been a long-standing effort, especially in view of its High-Luminosity (HL) upgrade. The resulting impedance model is an essential input for beam dynamics studies. [...]
2024 - 4 p.
- Published in : JACoW HB 2023 (2024) 559-562
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.559-562
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Mitigation Strategies for the Instabilities Induced by the Fundamental Mode of the HL-LHC Crab Cavities
/ Giacomel, Lorenzo (CERN) ; Baudrenghien, Philippe (CERN) ; Buffat, Xavier (CERN) ; Calaga, Rama (CERN) ; Mounet, Nicolas (CERN)
The transverse impedance is one of the potentially limiting effects for the performance of the High-Luminosity Large Hadron Collider (HL-LHC). In the current LHC, the impedance is dominated by the resistive-wall contribution of the collimators at typical bunch-spectrum frequencies, and is of broad-band nature. [...]
2024 - 4 p.
- Published in : JACoW HB 2023 (2024) 571-574
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.571-574
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High intensity beam dynamics assessment and challenges for HL-LHC
/ Rumolo, G (CERN) ; Salvant, B (CERN) ; Mounet, N (CERN) ; Tomás, R (CERN) ; Bartosik, H (CERN) ; Baudrenghien, P (CERN) ; Bruce, R (CERN) ; Buffat, X (CERN) ; Calaga, R (CERN) ; De Maria, R (CERN) et al.
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. [...]
2024 - 7 p.
- Published in : JINST
- Published in : JACoW HB: 2023 (2024) , pp. 344-350
Fulltext: PublicationJACoW - PDF; PublicationIOP - 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.T05016
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Head-tail mode zero instability growth rate studies in the CERN SPS
/ de la Fuente, E (CERN) ; Mases, I (CERN) ; Bartosik, H (CERN) ; Zannini, C (CERN)
The Head-Tail mode 0 instability growth rate is related to the real part of the transverse beam coupling impedance. The SPS transverse impedance model, which includes the major impedance contributions in the machine, can be benchmarked through measurements of growth rate as function of chromaticity [...]
2023 - 4 p.
- Published in : JACoW IPAC 2023 (2023) WEPL155
Fulltext: PDF;
In : 14th International Particle Accelerator Conference (IPAC 2023), Venice, Italy, 7 - 12 May 2023, pp.WEPL155
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Mitigation strategies for the instabilities induced by the fundamental mode of the HL-LHC Crab Cavities
/ Giacomel, L (CERN) ; Baudrenghien, P (CERN) ; Calaga, R (CERN) ; Buffat, X (CERN) ; Mounet, N (CERN)
The transverse impedance is one of the potentially limitingeffects for the performance of the High-Luminosity Large HadronCollider (HL-LHC). In the current LHC, the impedance is dominatedby the resistive-wall contribution of the collimators at typicalbunch-spectrum frequencies, and is of broad-bandnature. [...]
2024 - 14 p.
- Published in : JINST 19 (2024) P05046
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.P05046
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Impedance-induced beam observables in the CERN Proton Synchrotron
/ Joly, S (Rome U.) ; Migliorati, M (Rome U. ; CERN) ; Delrieux, M (CERN) ; Imesch, G (CERN) ; Mounet, N (CERN) ; Salvant, B (CERN)
Impedance-induced tune shifts and instability growth rates in the CERN Proton Synchrotron are studied thanks to the recently updated impedance model of the machine. Calculation of these beam observables are obtained using both Vlasov solvers and macroparticle tracking simulations, and are compared with those observed during dedicated measurement campaigns. [...]
2023 - 4 p.
- Published in : JACoW IPAC 2023 (2023) WEPL149
Fulltext: PDF;
In : 14th International Particle Accelerator Conference (IPAC 2023), Venice, Italy, 7 - 12 May 2023, pp.WEPL149
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Mitigating Collimation Impedance and Improving Halo Cleaning with New Optics and Settings Strategy of the HL-LHC Betatron Collimation System
/ Lindström, Bjorn (CERN) ; Bruce, Roderik (CERN) ; Buffat, Xavier (CERN) ; De Maria, Riccardo (CERN) ; Giacomel, Lorenzo (CERN) ; Hermes, Pascal (CERN) ; Mirarchi, Daniele (CERN) ; Mounet, Nicolas (CERN) ; Persson, Tobias (CERN) ; Redaelli, Stefano (CERN) et al.
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. [...]
2024 - 5 p.
- Published in : JACoW HB 2023 (2024) 183-187
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.183-187
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Understanding of the LHC warm vacuum module heating
/ Krkotic, Patrick (CERN) ; Baglin, Vincent (CERN) ; Chiggiato, Paolo (CERN) ; Papaphilippou, Yannis (CERN) ; Rumolo, Giovanni (CERN) ; Antuono, Chiara (CERN ; Rome U.) ; Bregliozzi, Giuseppe (CERN) ; Calatroni, Sergio (CERN) ; de la Fuente, Elena (CERN ; Madrid, Polytechnic U.) ; Galloro, Alessio (Calabria U. ; CERN) et al.
During the third run of the Large Hadron Collider in 2023, which had the highest intensity bunch population compared to previous runs, increased losses attributed to pressure spikes within a warm vacuum sector triggered a beam dump. Subsequent inspections revealed localised annealing and plasticisation of the tension spring in the sliding contact radio-frequency finger module, alongside traces of vapour deposition on the various module components with the stainless-steel spring material. [...]
2024 - 4 p.
- Published in : JACoW IPAC 2024 (2024) TUAN3
Fulltext: PDF;
In : 15th International Particle Accelerator Conference (IPAC 2024), Nashville, TN, United States, 19 - 24 May 2024, pp.TUAN3
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