Related papers: Operational considerations on the stability of col…
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…
This paper introduces a list of observations related to the beam-beam interaction that were collected over the first years of LHC proton physics operation (2010-12). Beam-beam related effects not only have been extensively observed and…
This paper describes two distinct effects observed during the operation of the LHC in 2012: first, the impacts on beam parameter evolution of the end-of-squeeze instabilities encountered in the second half of the 2012 run; and, second, the…
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…
One of the key sources of transverse impedance in the LHC has been the secondary graphite collimators that sit close to the beam at all energies. This limits the stable bunch intensity due to transverse coupled-bunch instabilities and…
The Higher-Energy LHC (HE-LHC) should collide two proton beams of 16.5-TeV energy, circulating in the LHC tunnel. We discuss the main parameter choices, as well as some optics and beam dynamics issues, in particular the time evolution of…
In polarized proton operation in the Relativistic Heavy Ion Collider (RHIC) coherent beam-beam modes are routinely observed with beam transfer function measurements. These modes can become unstable under external excitation or in the…
The CERN Large Hadron Collider (LHC) is designed to collide proton beams of unprecedented energy, in order to extend the frontiers of high-energy particle physics. During the first very successful running period in 2010--2013, the LHC was…
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…
The effect of the beam-beam interactions on the stability of impedance mode is discussed. The detuning is evaluated by the means of single particle tracking in arbitrarily complex collision configurations, including lattice non-linearities,…
The Supper Proton-Proton Collider is a next-generation hadron collider that is now being designed. A baseline design aims for a peak luminosity of about 1*10^35 cm^-2 s^-1. The focus of this article is the effect of beam-beam interactions…
The High-Luminosity upgrade of the Large Hadron Collider (HL-LHC) will double its beam intensity for the needs of High Energy Physics frontier. In order to ensure coherent stability until the beams are put in collision, the transverse…
Long-range beam-beam effects are a potential limit to the LHC performance with the nominal design parameters, and certain upgrade scenarios under discussion. To mitigate long-range effects, current carrying wires parallel to the beam were…
As two counter-rotating beams interact they can give rise to coherent dipole modes. Under the influence of impedance these coherent beam-beam modes can couple to higher order head-tail modes and lead to strong instabilities. A fully…
Hosting six different experiments at four different interaction points and widely different requirements for the running conditions, the LHC machine has been faced with a long list of challenges in the first three years of luminosity…
This paper begins with a summary of the status of the Large Hadron Collider at CERN, including the lead-ion injector chain and the plans for the first phases of commissioning and operation with colliding proton beams. In a later phase, the…
The variety of beams, needed to set-up in the injectors as requested in the LHC, are reviewed, in terms of priority but also performance expectations and reach during 2015. This includes the single bunch beams for machine commissioning and…
Coupling of the quark-gluon plasma from the early stage of heavy-ion collisions is argued to be weaker at LHC than at RHIC. For this reason, the role of instabilities - the pre-equilibrium plasma is unstable with respect to chromomagnetic…
Two 6-t beam dumps, made of a graphite core encapsulated in a stainless steel vessel, are used to absorb the energy of the two Large Hadron Collider (LHC) intense proton beams during operation of the accelerator. Operational issues started…
In high intensity and high energy colliders such as the CERN Large Hadron Collider and its future High Luminosity upgrade, interactions between the two beams around the different Interaction Points impose machine performance limitations. In…