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Hasse, R.W.

Paper Title Page
WEPCH119 Beam Performance with Internal Targets in the High-energy Storage Ring (HESR) 2197
 
  • A. Lehrach, R. Maier, D. Prasuhn
    FZJ, Jülich
  • O. Boine-Frankenheim, R.W. Hasse
    GSI, Darmstadt
  • F. Hinterberger
    Universität Bonn, Helmholtz-Institut für Strahlen- und Kernphysik, Bonn
 
  The High-energy Storage Ring of the future International Facility for Antiproton and Ion Research (FAIR) at GSI in Darmstadt is planned as an antiproton synchrotron storage ring in the momentum range of 1.5 to 15 GeV/c. An important feature of HESR is the combination of phase space cooled beams and dense internal targets (e.g., pellet targets), which results in demanding beam parameter requirements for two operation modes: high luminosity mode with peak luminosities of up to 2·1032 cm-2 s-1, and high resolution mode with a momentum spread down to 10-5, respectively. The beam cooling equilibrium and beam loss with internal target interaction is analyzed. Rate equations are used to predict the rms equilibrium beam parameters. The cooling and intra-beam scattering rate coefficients are obtained from simplified models. Energy loss straggling in the target and the associated beam loss are analyzed analytically assuming a thin target. A longitudinal kinetic simulation code is used to study the evolution of the momentum distribution in coasting and bunched beam. The analytic expressions for the target induced momentum tail are found in good agreement with the simulation results.

*A. Lehrach et al. Beam Performance and Luminosity Limitations in the High-Energy Storage Ring (HESR), Nuclear Inst. and Methods in Physics Research, A44704 (2006).

 
THPCH034 Transverse Coupling Impedances From Field Matching in a Smooth Resistive Cylindrical Pipe for Arbitrary Beam Energies 2853
 
  • A.M. Al-Khateeb, A.M. Al-Khateeb, W.M. Daqa
    Yarmouk, Irbid
  • O. Boine-Frankenheim, R.W. Hasse, I. Hofmann
    GSI, Darmstadt
 
  The transverse coupling impedance is investigated analytically. For an off-axis motion of the beam, the perturbed charge distribution of the beam becomes a function of the azimuthal angle, resulting to first order in the beam displacement in a dipole term which is the source of the transverse impedance. All six components of the electromagnetic field are different from zero and, therefore, both TM and TE modes will be excited in the beam-pipe and coupled to the beam at the inner surface of the resistive wall. Using the dipole source term, a linear combination of TM and TE modes is used to get closed form expressions for the transverse electromagnetic field components excited in the beam-pipe, and a generalized analytic expression for the corresponding transverse coupling impedance. It has been found that the contributions of the TM and the TE modes to the real part of the transverse resistive-wall impedance have similar dependence on the relativistic parameter but with opposite signs, the sum of both always being positive. Some approximate simple formulas for three important regions corresponding to small, intermediate and large frequencies in the ultrarelativistic limit were also obtained analytically.