WEP1WA —  WG-A   (20-Jun-18   14:00—15:30)
Chair: Y.H. Chin, KEK, Ibaraki, Japan
Paper Title Page
Simulations of Electron-Ion Effects and Relevance to LHC Experience in 2017  
  • L. Mether
    EPFL, Lausanne, Switzerland
  • G. Iadarola, G. Rumolo
    CERN, Geneva, Switzerland
  Operation of the LHC in 2017 was severely affected by recurrent beam aborts triggered by beam losses in one of its arc cells. The losses were correlated with quickly developing transverse coherent oscillations, which in most cases caused the beam dumps due to particle losses in the cleaning insertions. The events are thought to have been caused by air that was frozen on the beam screen surface in the concerned location, and which through a complex sequence of events could give rise to a localized high gas density. In this contribution we describe efforts towards modelling the observed coherent effects through the interaction of the beam with the induced pressure bump.  
slides icon Slides WEP1WA01 [10.532 MB]  
Beam-Beam Studies in Present and Future Hadron Colliders  
  • Y. Papaphilippou
    CERN, Geneva, Switzerland
  The impact on beam-beam effects in the non-linear dynamics of colliding hadron beams is reviewed, with emphasis on simulation and measurement examples from the LHC and its High-Luminosity upgrade (HL-LHC). The main limitation encountered is the effect of the beam-beam long range (BBLR) interaction which limits the beam lifetime at collision and is well correlated with the minimum dynamic aperture (DA), as shown by measurements in the LHC. Thereby, multi-parametric DA simulations are used as a guide in order to define the collider settings and beam parameters through the LHC run. The same approach is used for validating the operational HL-LHC scenario and improving the beam performance at collision. Recent studies on the impact of tune modulation to the collider lifetime are briefly described. Finally, the potential of BBLR compensation in the HL-LHC era is evaluated through simulations and LHC machine studies.  
slides icon Slides WEP1WA02 [6.355 MB]  
WEP1WA03 IBS Near Transition Crossing in NICA Collider -1
  • S.A. Kostromin, A.O. Sidorin
    JINR, Dubna, Moscow Region, Russia
  • I.V. Gorelyshev
    JINR/VBLHEP, Dubna, Moscow region, Russia
  • V.A. Lebedev
    Fermilab, Batavia, Illinois, USA
  • A.O. Sidorin
    Saint Petersburg State University, Saint Petersburg, Russia
  Intrabeam scattering (IBS) of charged particles in a particle beam results in an exchange of energy between different degrees of freedom. That results in an increase of average energy of particles in the beam frame and an increase of the 3D-emittance. The paper considers calculations of beam emittance growth rates for different options of NICA collider and IBS effects in close vicinity of the transition.  
slides icon Slides WEP1WA03 [1.774 MB]