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31.
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32.
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LHC Full Energy Exploitation Study: Operation at Ultimate Energy of 7.5 TeV
/ Bruning, Oliver (CERN) ; Antipov, Sergey (CERN) ; Amorim, David (Universite Grenoble-Alpes (FR)) ; Arduini, Gianluigi (CERN) ; Apollonio, Andrea (CERN) ; Ball, Austin (CERN) ; Baglin, Vincent (CERN) ; Bartmann, Wolfgang (CERN) ; Battistin, Michele (CERN) ; Biancacci, Nicolo (CERN) et al.
This report discusses the feasibility and limitations for operating the LHC and HL-LHC at the ultimate beam energy of 7.5 TeV, corresponding to a main dipole magnetic field of 8.93 T and an operating current of 12748 A..
CERN-ACC-2019-0015.
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2019. - 57 p.
Full text
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33.
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Staged implementation of low-impedance collimation in IR7: plans for LS2
/ Redaelli, Stefano (CERN) ; Antipov, Sergey (CERN) ; Biancacci, Nicolo (CERN) ; Bertarelli, Alessandro (CERN) ; Bruce, Roderik (CERN) ; Carra, Federico (CERN) ; Gobbi, Giorgia (CERN) ; Lechner, Anton (CERN) ; Mereghetti, Alessio (CERN) ; Metral, Elias (CERN)
The HL-LHC upgrade baseline foresees to replace all secondary collimators of IR7 until LS3 in order to ensure a sufficient margin for beam stability with the high-brightness upgraded beams. [...]
CERN-ACC-NOTE-2019-0001.
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2019. - 30 p.
Full text
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34.
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HL-LHC impedance and related effects
/ Amorim, David (Universite Grenoble-Alpes (FR)) ; Antipov, Sergey (CERN) ; Biancacci, Nicolo (CERN) ; Salvant, Benoit (CERN) ; Arpaia, Pasquale (Universita e sezione INFN di Napoli (IT)) ; Barnes, Mike (CERN) ; Bonanno, Edoardo (Universita degli studi di Palermo (IT)) ; Calaga, Rama (CERN) ; Carideo, Emanuela (Universita del Sannio (IT)) ; Day, Hugo Alistair et al.
This note aims at gathering the work done by CERN and collaborators on the HL-LHC beam coupling impedance in the recent years and identifying the next steps [...]
CERN-ACC-NOTE-2018-0087.
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2018. - 93 p.
Full text
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35.
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Space charge impedance and electromagnetic fields in elliptical vacuum chambers
/ Migliorati, Mauro (U. Rome La Sapienza (main) ; INFN, Rome) ; Biancacci, Nicolo (CERN) ; Masullo, Maria Rosaria (INFN, Naples) ; Palumbo, Luigi (U. Rome La Sapienza (main) ; INFN, Rome) ; Vaccaro, Vittorio (INFN, Naples ; Naples U.)
Starting from the electric fields produced by a point charge and a dipole travelling inside a circular vacuum chamber, in this paper we derive a formalism for a complete set of equations that describe the electromagnetic fields and the longitudinal and transverse coupling impedance arising by the interactions of a beam with a perfectly conducting pipe in the case of elliptic geometry. The expressions, which are valid for any frequency and beam energy, are written in terms of expansion of Mathieu functions, allow to range from a circular geometry to the parallel plates, and show an interesting parallelism with the well known expressions for a circular pipe. [...]
CERN-ACC-NOTE-2018-0080.-
Geneva : CERN, 2018 - 12 p.
- Published in : Phys. Rev. Accel. Beams 21 (2018) 124201
Fulltext: CERN-ACC-NOTE-2018-0080 - PDF; PhysRevAccelBeams.21.124201 - PDF;
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36.
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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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37.
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Space Charge Studies on LEIR
/ Saá Hernández, Angela (CERN) ; Bartosik, Hannes (CERN) ; Biancacci, Nicolo (CERN) ; Hirlaender, Simon (CERN) ; Huschauer, Alexander (CERN) ; Moreno Garcia, Daniel (CERN)
The performance of the CERN Low Energy Ion Ring with electron cooled ion beams is presently limited by losses occurring once the beam has been captured in the RF buckets. An intense machine study program was started by the end of 2015 to mitigate the losses and improve the performance of the accelerator. [...]
CERN-ACC-2018-134.-
2018 - 6 p.
- Published in : (2018) , pp. THPAF055
- Published in : J. Phys.: Conf. Ser. 1067 (2018) 062020
Fulltext: PDF;
In : 9th International Particle Accelerator Conference, Vancouver, Canada, 29 Apr - 4 May 2018, pp.THPAF055
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38.
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Longitudinal and Quadrupolar Coupling Impedance of an Elliptical Vacuum Chamber With Finite Conductivity in Terms of Mathieu Functions
/ Migliorati, Mauro (Rome U. ; INFN, Rome ; CERN) ; Biancacci, Nicolo (CERN) ; Palumbo, Luigi (Rome U. ; INFN, Rome) ; Vaccaro, Vittorio (INFN, Naples ; Naples U.)
The resistive wall impedance of an elliptical vacuum chamber in the classical regime with infinite thickness is known analytically for ultra-relativistic beams by means of the Yokoya form factors. Starting from the longitudinal electric field of a point charge moving at arbitrary speed in an elliptical vacuum chamber, which we express in terms of Mathieu functions, in this paper we take into account the finite conductivity of the beam pipe walls and evaluate the longitudinal and quadrupolar impedance for any beam velocity. [...]
IPAC-2018-THPAF036; CERN-ACC-2018-135.-
2018 - 4 p.
- Published in : 10.18429/JACoW-IPAC2018-THPAF036
Fulltext: PDF;
In : 9th International Particle Accelerator Conference, Vancouver, Canada, 29 Apr - 4 May 2018, pp.THPAF036
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39.
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LEIR Injection Efficiency Studies as a Function of the Beam Energy Distribution from Linac3
/ Hirlaender, Simon (CERN) ; Alemany-Fernández, Reyes (CERN) ; Bartosik, Hannes (CERN) ; Bellodi, Giulia (CERN) ; Biancacci, Nicolo (CERN) ; Kain, Verena (CERN) ; Scrivens, Richard (CERN)
High intensities in the CERN Low Energy Ion Ring (LEIR) are achieved using multi-turn injections from the pre-accelerator Linac3 combined with simultaneous stacking in momentum and transverse phase spaces. Up to seven consecutive 200 $\mu$s long, 200 ms spaced pulses are injected from Linac3 into LEIR by stacking each of them into the six-dimensional phase-space over 70 turns. [...]
CERN-ACC-2018-142.-
2018 - 3 p.
- Published in : 10.18429/JACoW-IPAC2018-TUPAF034
Fulltext: PDF;
In : 9th International Particle Accelerator Conference, Vancouver, Canada, 29 Apr - 4 May 2018, pp.TUPAF034
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40.
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Impedance and Instability Studies in LEIR with Xenon
/ Biancacci, Nicolo (CERN) ; Bartosik, Hannes (CERN) ; Gąsior, Marek (CERN) ; Hirlaender, Simon (CERN) ; Latina, A (CERN) ; Levens, Thomas (CERN) ; Migliorati, Mauro (U. Rome La Sapienza (main) ; INFN, Rome) ; Métral, Elias (CERN)
In 2017, the LEIR accelerator has been operated with $Xe^{39+}$ beam for fixed target experiments in the SPS North Area. The different ion species, with respect to the standard $Pb^{34+}$, allowed for additional comparative measurements of tune shift versus intensity at injection energy both in coasting and bunched beams. [...]
CERN-ACC-2018-143.-
2018 - 4 p.
- Published in : 10.18429/JACoW-IPAC2018-TUPAF024
Fulltext: PDF;
In : 9th International Particle Accelerator Conference, Vancouver, Canada, 29 Apr - 4 May 2018, pp.TUPAF024
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