180 research outputs found
BTF measurements with beam-beam interactions
We present considerations about the transverse beam transfer function (BTF)
of beams under the influence of two effects: The strong-strong beam-beam effect
and the influence of a Gaussian electron lens. The BTF are investigated using
two methods: BTF excitation is simulated in a particle-in-cell (PIC) code. The
BTF model is verified using a known analytic expectation. Analytic expectations
for BTF of beams under a stationary electron lens are derived by extending BTF
from the formalism of Berg and Ruggiero. Finally we compare the analytic BTF
results for a stationary Gaussian lens to both the PIC simulation for split
tune conditions and to PIC simulations for a beam influenced by an electron
lens. We conclude that the formalism represents the electron lens well and can
be applied to a limited extend to the beam-beam effect under split tune
conditions. The analytic formalism allows us to recover the strength of an
electron lens by means of fitting and can give clues regarding the strength of
the beam-beam effect under split tune conditions.Comment: 5 pages, contribution to the ICFA Mini-Workshop on Beam-Beam Effects
in Hadron Colliders, CERN, Geneva, Switzerland, 18-22 Mar 201
Analysis of resonancesinduced by the SIS-18 electron cooler
Besides beam cooling, an electron cooler also acts as a non-linear optical element. This may lead to the excitation of resonances possibly resulting in an increase of the beam emittance. The aim of this work is the calculation of resonances driven by the electron space charge field in the cooler installed in the SIS heavy ion synchrotron at GSI Darmstadt. For our calculations, we used a numerical model consisting of a rotation matrix representing the ideal lattice together with a non-linear transverse kick element representing the electron cooler. Within this model, we studied the dominant resonance lines resulting from the interaction with the cooler
Beam halo collimation in heavy ion synchrotrons
This paper presents a systematic study of the halo collimation of ion beams from proton up to uranium in synchrotrons. The projected Facility for Antiproton and Ion Research synchrotron SIS100 is used as a reference case. The concepts are separated into fully stripped (e.g., ^{238}U^{92+}) and partially stripped (e.g., ^{238}U^{28+}) ion collimation. An application of the two-stage betatron collimation system, well established for proton accelerators, is intended also for fully stripped ions. The two-stage system consists of a primary collimator (a scattering foil) and secondary collimators (bulky absorbers). Interaction of the particles with the primary collimator (scattering, momentum losses, and nuclear interactions) was simulated by using fluka. Particle-tracking simulations were performed by using mad-x. Finally, the dependence of the collimation efficiency on the primary ion species was determined. The influence of the collimation system adjustment, lattice imperfections, and beam parameters was estimated. The concept for the collimation of partially stripped ions employs a thin stripping foil in order to change their charge state. These ions are subsequently deflected towards a dump location using a beam optical element. The charge state distribution after the stripping foil was obtained from global. The ions were tracked by using mad–x
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