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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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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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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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Numerical methods for emittance computation from luminosity
/ Rufolo, Matteo (Dalle Molle Inst. AI Studies, Lugano) ; Fornara, Andrea (Manchester U. ; CERN) ; Lamb, Elleanor (Ecole Polytechnique, Lausanne ; CERN) ; Sterbini, Guido (CERN) ; Giacomel, Lorenzo (CERN)
The beam transverse emittances play a critical role in high-energy colliders. Various measurement techniques are employed to measure them. [...]
2024 - 4 p.
- Published in : JACoW IPAC 2024 (2024) MOPC19
Fulltext: PDF;
In : 15th International Particle Accelerator Conference (IPAC 2024), Nashville, TN, United States, 19 - 24 May 2024, pp.MOPC19
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Electron Cloud Effects in the CERN Accelerators in Run 3
/ Mether, Lotta (CERN) ; Bartosik, Hannes (CERN) ; Giacomel, Lorenzo (CERN) ; Iadarola, Giovanni (CERN) ; Johannesson, Sofia (CERN) ; Mases Solé, Ingrid (CERN) ; Paraschou, Konstantinos (CERN) ; Rumolo, Giovanni (CERN) ; Sabato, Luca (CERN) ; Zannini, Carlo (CERN) et al.
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. [...]
2024 - 5 p.
- Published in : JACoW HB 2023 (2024) 538-542
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.538-542
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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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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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Collimation of 400 MJ Beams at the LHC: The First Step Towards the HL-LHC Era
/ Redaelli, Stefano (CERN) ; Abramov, Andrey (CERN) ; Baillard, Dylan (CERN) ; Bruce, Roderik (CERN) ; Cai, Rongrong (CERN ; Ecole Polytechnique, Lausanne) ; Carra, Federico (CERN) ; D'Andrea, Marco (CERN) ; Di Castro, Mario (CERN) ; Giacomel, Lorenzo (CERN) ; Hermes, Pascal (CERN) et al.
An important upgrade programme is planned for the collimation system of the CERN Large Hadron Collider (LHC) in order to meet the challenges of the upcoming High-Luminosity LHC (HL-LHC) project. A first stage of the HL-LHC upgrade was already deployed during the last LHC Long Shutdown, offering important improvements of the collimation cleaning, a significant reduction of the impedance contribution and better cleaning of collisional debris, in particular for ion-ion collisions. [...]
2024 - 4 p.
- Published in : JACoW HB 2023 (2024) 603-606
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.603-606
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