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Low-Impedance Collimators for HL-LHC
/ Antipov, Sergey (CERN) ; Amorim, David (U. Grenoble Alpes) ; Bertarelli, A (CERN) ; Biancacci, Nicolo (CERN) ; Bruce, Roderik (CERN) ; Mereghetti, Alessio (CERN) ; Mirarchi, Daniele (CERN) ; Métral, Elias (CERN) ; Redaelli, Stefano (CERN) ; Salvant, Benoit (CERN)
The High-Luminosity upgrade of the Large Hadron Collider (HL-LHC) will double its beam intensity for the needs of High Energy Physics frontier. This increase requires a reduction of the machine's impedance to ensure the coherent stability of the beams until they are put in collision. [...]
CERN-ACC-2018-147.-
2018 - 4 p.
- Published in : 10.18429/JACoW-IPAC2018-WEYGBE4
Fulltext: PDF;
In : 9th International Particle Accelerator Conference, Vancouver, Canada, 29 Apr - 4 May 2018, pp.WEYGBE4
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2.
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Single-Collimator Tune Shift Measurement of the Three-Stripe Collimator at the LHC
/ Antipov, Sergey (CERN) ; Amorim, David (U. Grenoble Alpes) ; Biancacci, Nicolo (CERN) ; Carver, Lee (CERN) ; Mazzacano, Giacomo (U. Rome La Sapienza (main)) ; Mereghetti, Alessio (CERN) ; Métral, Elias (CERN) ; Redaelli, Stefano (CERN) ; Salvant, Benoit (CERN) ; Valuch, Daniel (CERN)
Several options of low resistivity coating have been proposed for the collimator upgrade of the Large Hadron Collider. In order to study their effect on the beam dynamics a special collimator has been built and installed in the machine. [...]
CERN-ACC-2018-148.-
2018 - 4 p.
- Published in : 10.18429/JACoW-IPAC2018-THPAF035
Fulltext: PDF;
In : 9th International Particle Accelerator Conference, Vancouver, Canada, 29 Apr - 4 May 2018, pp.THPAF035
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3.
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Experimental Characterisation of a Fast Instability Linked to Losses in the 16L2 Cryogenic Half-Cell in the CERN LHC
/ Salvant, Benoit (CERN) ; Antipov, Sergey (CERN) ; Arduini, Gianluigi (CERN) ; Biancacci, Nicolo (CERN) ; Buffat, Xavier (CERN) ; Carver, Lee (CERN) ; Collier, Paul (CERN) ; Gorzawski, Arkadiusz (CERN) ; Höfle, Wolfgang (CERN) ; Iadarola, Giovanni (CERN) et al.
The operation during the summer months of the 2017 Run of the CERN LHC was plagued with fast beam losses that repeatedly occurred in the 16th arc half-cell at the left of IP2 as well as in the collimation insertion, leading to unwanted beam dumps. Transverse coherent oscillations were observed during this fast process. [...]
CERN-ACC-2018-175.-
2018 - 4 p.
- Published in : 10.18429/JACoW-IPAC2018-THPAF058
Fulltext: PDF;
In : 9th International Particle Accelerator Conference, Vancouver, Canada, 29 Apr - 4 May 2018, pp.THPAF058
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4.
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Simulation and Measurement of the TMCI Threshold in the LHC
/ Amorim, David (CERN ; U. Grenoble Alpes) ; Antipov, Sergey (CERN) ; Biancacci, Nicolo (CERN) ; Buffat, Xavier (CERN) ; Carver, Lee (CERN) ; Métral, Elias (CERN)
The Transverse Mode Coupling Instability (TMCI) occurs in individual bunches when two transverse oscillation modes couple at high intensity. Simulations predict an instability threshold in the LHC at a single bunch intensity of $3 \cdot 10^{11}$ protons. [...]
2018 - 5 p.
- Published in : 10.18429/JACoW-HB2018-MOP2WA05
Fulltext: PDF;
In : 61st ICFA Advanced Beam Dynamics Workshop on High-Intensity and High-Brightness Hadron Beams, Daejeon, Korea, 17 - 22 Jun 2018, pp.MOP2WA05
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5.
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Instability Observations in the Large Hadron Collider During Run 2
/ Carver, Lee (CERN) ; Amorim, David (CERN) ; Antipov, Sergey (CERN) ; Biancacci, Nicolo (CERN) ; Buffat, Xavier (CERN) ; Iadarola, Giovanni (CERN) ; Li, Kevin (CERN) ; Maclean, Ewen (CERN) ; Mether, Lotta (CERN ; Ecole Polytechnique, Lausanne) ; Métral, Elias (CERN) et al.
Instabilities of many different types and characteristics have been observed in the LHC during Run 2. The origin of these instabilities come from a variety of stabilising and destabilising mechanisms. [...]
CERN-ACC-2018-149.-
2018 - 4 p.
- Published in : 10.18429/JACoW-IPAC2018-THPAF057
Fulltext: PDF;
In : 9th International Particle Accelerator Conference, Vancouver, Canada, 29 Apr - 4 May 2018, pp.THPAF057
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6.
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Building the impedance model of a real machine
/ Salvant, Benoit (CERN) ; Amorim, David (CERN ; Grenoble, INP) ; Antipov, Sergey (CERN) ; Arsenyev, Sergey (CERN) ; Beck, Mario (CERN) ; Biancacci, Nicolo (CERN) ; Brüning, Oliver (CERN) ; Campelo, Jose Enrique (CERN) ; Carideo, Emanuela (CERN) ; Caspers, Fritz (CERN) et al.
A reliable impedance model of a particle accelerator can be built by combining the beam coupling impedances of all the components. This is a necessary step to be able to evaluate the machine performance limitations, identify the main contributors in case an impedance reduction is required, and study the interaction with other mechanisms such as optics nonlinearities, transverse damper, noise, space charge, electron cloud, beam-beam (in a collider). [...]
CERN-ACC-2019-098.-
2019 - 6 p.
- Published in : 10.18429/JACoW-IPAC2019-WEYPLS1
Fulltext from publisher: PDF;
In : 10th International Particle Accelerator Conference, Melbourne, Australia, 19 - 24 May 2019, pp.WEYPLS1
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7.
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Instability latency in the LHC
/ Furuseth, Sondre (CERN ; Ecole Polytechnique, Lausanne) ; Amorim, David (CERN) ; Antipov, Sergey (CERN) ; Buffat, Xavier (CERN) ; Mounet, Nicolas (CERN) ; Métral, Elias (CERN) ; Pieloni, Tatiana (Ecole Polytechnique, Lausanne) ; Salvant, Benoit (CERN) ; Tambasco, Claudia (Ecole Polytechnique, Lausanne)
The Large Hadron Collider (LHC) has experienced multiple instabilities that occur between minutes and hours after the last modification of the machine settings. The existence of instabilities with high latency has been reproduced also in simulations. [...]
CERN-ACC-2019-116.-
2019 - 4 p.
- Published in : 10.18429/JACoW-IPAC2019-WEPTS044
Fulltext from publisher: PDF;
In : 10th International Particle Accelerator Conference, Melbourne, Australia, 19 - 24 May 2019, pp.WEPTS044
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8.
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Destabilising Effect of the LHC Transverse Damper
/ Métral, Elias (CERN) ; Amorim, David (CERN) ; Antipov, Sergey (CERN) ; Biancacci, Nicolo (CERN) ; Buffat, Xavier (CERN) ; Li, Kevin (CERN)
Three questions motivated this study for the CERN Large Hadron Collider in terms of beam stability: (i) why a chromaticity close to zero seemed more critical than predicted during Run 1 (in 2011 and 2012) and during Run 2 (in 2015)?; (ii) why some past simulations with a chromaticity close to zero revealed a more critical situation with the transverse damper than without?; (iii) what should be the minimum operational chromaticity in the future in the LHC and High-Luminosity LHC? A new Vlasov solver (called GALACTIC) was developed to shed light on the destabilising mechanism of the transverse damper, which is a potential contributor to explain the LHC observation. Due to the features, which are discussed in this paper, the name 'ISR (for Imaginary tune Split and Repulsion) instability' is suggested for this new kind of single-bunch instability with zero chromaticity..
CERN-ACC-2018-129.-
2018 - 4 p.
- Published in : 10.18429/JACoW-IPAC2018-THPAF048
Fulltext: PDF;
In : 9th International Particle Accelerator Conference, Vancouver, Canada, 29 Apr - 4 May 2018, pp.THPAF048
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9.
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Observations, Analysis and Mitigation of Recurrent LHC Beam Dumps Caused by Fast Losses in Arc Half-Cell 16L2
/ Jimenez, José (CERN) ; Amorim, David (CERN ; U. Grenoble Alpes) ; Antipov, Sergey (CERN) ; Arduini, Gianluigi (CERN) ; Bertarelli, Alessandro (CERN) ; Biancacci, Nicolo (CERN) ; Bradu, Benjamin (CERN) ; Bravin, Enrico (CERN) ; Bregliozzi, Giuseppe (CERN) ; Brodzinski, Krzysztof (CERN) et al.
Recurrent beam dumps significantly perturbed the operation of the CERN LHC in the summer months of 2017, especially in August. These unexpected beam dumps were triggered by fast beam losses that built up in the cryogenic beam vacuum at the half-cell 16 left of LHC-IP2 and were detected either at that location but mainly in the collimation insertions. [...]
CERN-ACC-2018-164.-
2018 - 4 p.
- Published in : 10.18429/JACoW-IPAC2018-MOPMF053
Fulltext: PDF;
In : 9th International Particle Accelerator Conference, Vancouver, Canada, 29 Apr - 4 May 2018, pp.MOPMF053
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10.
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The High Energy LHC Beam-Beam Effects studies
/ Pieloni, Tatiana (Ecole Polytechnique, Lausanne) ; Amorim, David (CERN) ; Antipov, Sergey (CERN) ; Barranco García, Javier (Ecole Polytechnique, Lausanne) ; Buffat, Xavier (CERN) ; Rivkin, Leonid (Ecole Polytechnique, Lausanne) ; Salvant, Benoit (CERN) ; Tambasco, Claudia (Ecole Polytechnique, Lausanne) ; Zimmermann, Frank (CERN)
We present in this paper the studies of beam-beam effects for the High Energy Large Hadron Collider. We will describe and review the different aspects of beam-beam interactions (i.e. [...]
CERN-ACC-2018-074.-
2018 - 4 p.
- Published in : 10.18429/JACoW-IPAC2018-MOPMF069
Fulltext: PDF;
In : 9th International Particle Accelerator Conference, Vancouver, Canada, 29 Apr - 4 May 2018, pp.MOPMF069
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