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Long Range Beam-beam Effects in the LHC  [PDF]
W. Herr,X. Buffat,R. Calaga,R. Giachino,G. Papotti,T. Pieloni,D. Kaltchev
Physics , 2014, DOI: 10.5170/CERN-2014-004.87
Abstract: We report on the experience with long-range beam--beam effects in the LHC, in dedicated studies as well as the experience from operation. Where possible, we compare the observations with the expectations.
Beam-beam-induced orbit effects at LHC  [PDF]
M. Schaumann,R. Alemany Fernandez
Physics , 2014, DOI: 10.5170/CERN-2014-004.231
Abstract: For high bunch intensities the long-range beam-beam interactions are strong enough to provoke effects on the orbit. As a consequence the closed orbit changes. The closed orbit of an unperturbed machine with respect to a machine where the beam-beam force becomes more and more important has been studied and the results are presented in this paper.
Beam-beam effects in the high-pile-up tests of the LHC  [PDF]
G. Trad
Physics , 2014, DOI: 10.5170/CERN-2014-004.75
Abstract: Investigating the beam-beam limit in the LHC is of great importance, since identifying its source is crucial for the luminosity optimization scenario. Several experiments were carried out to search for this limit and check whether it is dominated by the head-on (HO) or the long-range (LR) interactions. In this paper only the HO collision effects will be considered, tracking the evolution of the maximum tune shift achieved during the dedicated machine developments and the special high pile-up fills.
Proceedings of the ICFA Mini-Workshop on Beam-Beam Effects in Hadron Colliders (BB2013), CERN, Geneva, Switzerland, 18 - 22 Mar 2013  [PDF]
W. Herr,G. Papotti
Physics , 2014, DOI: 10.5170/CERN-2014-004
Abstract: This report contains the Proceedings of the ICFA Mini-Workshop on Beam-Beam Effects in Hadron Colliders held at CERN from 18 to 22 March 2013. It was the first of its kind after the successful start of LHC operation where a vast amount of beam-beam observations emerged. It brought together 58 international experts in the field and the purpose of this workshop was to review the present knowledge in the fields of beam-beam theory, simulations and observations. In the summary session the participants acknowledged the enormous progress made in recent years and the introduction of new concepts and tools. The workshop was concluded by a discussion on future research work with emphasis on the LHC operation and future circular colliders.
Coherent beam-beam mode in the LHC  [PDF]
X. Buffat,R. Calaga,R. Giachino,W. Herr,G. Papotti,T. Pieloni,S. White
Physics , 2014, DOI: 10.5170/CERN-2014-004.227
Abstract: Observations of single bunch beam-beam coherent modes during dedicated experiments in the LHC are presented. Their role in standard operation for physics is discussed and, in particular, candidates of beam-beam coherent mode driven unstable by the machine impedance are presented.
Beam-beam studies for the High-Energy LHC  [PDF]
K. Ohmi,O. Dominguez,F. Zimmermann
Physics , 2011,
Abstract: LHC upgrades are being considered both towards higher luminosity (HL-LHC) and towards higher energy (HE-LHC). In this paper we report initial studies of the beam-beam effects in the HE-LHC [1]. The HE-LHC aims at beam energies of 16.5 TeV, where the transverse emittance decreases due to synchrotron radiation with a 2-hour damping time. As a result of this emittance, shrinkage the beam-beam parameter increases with time, during a physics store. The beam-beam limit in the HE-LHC is explored using computer simulations.
HE-LHC: requirements from beam vacuum  [PDF]
J. M. Jimenez
Physics , 2011,
Abstract: First thoughts on the design of the beam vacuum system for the High Energy LHC (HE-LHC) are given with a particular focus on the impact of the synchrotron radiation. In the HE-LHC, the vacuum dynamic effects induced by the circulating beams are expected to be as compared to the LHC. These effects will be reviewed and first thoughts on how to avoid or mitigate their effects are discussed.
Three-beam instability in the LHC  [PDF]
Alexey Burov
Physics , 2013,
Abstract: In the LHC, a transverse instability is regularly observed at 4TeV right after the beta-squeeze, when the beams are separated by about their ten transverse rms sizes [1-3], and only one of the two beams is seen as oscillating. So far only a single hypothesis is consistent with all the observations and basic concepts, one about a third beam - an electron cloud, generated by the two proton beams in the high-beta areas of the interaction regions.
Electron Beam for LHC  [PDF]
Mieczyslaw Witold Krasny
Physics , 2004,
Abstract: A method of delivering a monochromatic electron beam to the LHC interaction points is proposed. In this method, heavy ions are used as carriers of the projectile electrons. Acceleration, storage and collision-stability aspects of such a hybrid beam is discussed and a new beam-cooling method is presented. This discussion is followed by a proposal of the Parasitic Ion-Electron collider at LHC (PIE@LHC). The PIE@LHC provides an opportunity, for the present LHC detectors, to enlarge the scope of their research program by including the program of electron-proton and electron-nucleuscollisions with minor machine and detector investments.
Simulation of beam-beam induced emittance growth in the HL-LHC with crab cavities  [PDF]
S. Paret,J. Qiang
Physics , 2014, DOI: 10.5170/CERN-2014-004.237
Abstract: The emittance growth in the HL-LHC due to beam-beam effects is examined by virtue of strong-strong computer simulations. A model of the transverse damper and the noise level have been tuned to simulate the emittance growth in the present LHC. Simulations with projected HL-LHC beam parameters and crab cavities are discussed. It is shown that with the nominal working point, the large beam-beam tune shift moves the beam into a resonance that causes substantial emittance growth. Increasing the working point slightly is demonstrated to be very beneficial.
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