• L. Haenichen, W.F.O. Müller, T. Weiland
  TEMF, TU Darmstadt, Darmstadt
• O. Boine-Frankenheim
  GSI, Darmstadt

Beam coupling impedances have been identified as an appropriate quantity to describe collective instabilities caused through beam-induced fields in heavy ion synchrotron accelerators such as the SIS-18 and the SIS-100 at the GSI facility. The impedance contributions caused by the multiple types of beamline components need to be determined to serve as input condition for later stability studies. This paper will discuss different approaches to calculate the Coupling Impedance contribution of ferrite devices, exploiting the abilities of both commercial codes such as CST STUDIO SUITE® and specific extensions of this code to address kicker related problems in particular. Before addressing actual beamline devices, benchmark problems with cylindrical and rectangular geometry will be simulated and the results will be compared with the corresponding analytical formulations.

• C. Eckardt, T. Bahlo, P. Bangert, R. Barday, U. Bonnes, M. Brunken, R. Eichhorn, J. Enders, M. Platz, Y. Poltoratska, M. Roth, F. Schneider, M. Wagner, A. Weber, B. Zwicker
  TU Darmstadt, Darmstadt
• W. Ackermann, W.F.O. Müller, T. Weiland
  TEMF, TU Darmstadt, Darmstadt

At the superconducting 130 MeV Darmstadt electron linac S-DALINAC* a source of polarized electrons** is being installed, extending the experimental capabilities with polarized electron and polarized photon probes for nuclear structure studies. This involves disassembling the existing low energy test stand and rebuilding the beam line in the accelerator hall. The beam itself is produced from a GaAs cathode by irradiation with a pulsed laser. The low-energy electron beam line includes diagnostic elements, a Wien filter for spin manipulation, a 100 keV Mott polarimeter for polarization measurement and a chopper-prebuncher section to modulate the time structure of the beam. At higher energies a 5-10 MeV Mott polarimeter and a 50-130 MeV Moeller polarimeter as well as a Compton transmission polarimeter will be installed to measure the beam polarization after acceleration. The Mott polarimeter is working with backscattered electrons under 165° scattering angle while for the Moeller polarimeter a wide-angle (3°-15°) spectrometer magnet was designed. We report on the performance of the test stand, the ongoing implementation, and the polarimeter research and development.

* A. Richter, Proc. EPAC 96, Sitges, p.110.
** Y. Poltoratska et al., AIP Conference Proc. 1149 (2009), p.983.