Author: Zimmermann, R.
Paper Title Page
MOPPR007 Investigation of Techniques for Precise Compton Polarimetry at ELSA 783
  • R. Zimmermann, W. Hillert
    ELSA, Bonn, Germany
  Funding: Work supported by DFG within SFB/TR16
A Compton polarimeter is currently being installed at the Electron Stretcher Facility ELSA to monitor the degree of polarization of the stored electron beam. For this purpose, circularly polarized light that is emitted by a laser and backscattered off the beam has to be detected. When the polarization of the laser light is switched from left-hand to right-hand circular polarization, the spatial distribution of the backscattered photons is shifted. The extent of this modification is a measure of the beam's polarization degree. Two different experimental techniques that are suitable for a measurement of the effect were compared and evaluated closer through numerical simulations that will be presented in this contribution.
WEPPP059 First Measurements with Multibunch Feedback Systems at the Fast Ramping Stretcher Ring ELSA 2840
  • M. Schedler, F. Frommberger, N. Heurich, W. Hillert, A. Roth, R. Zimmermann
    ELSA, Bonn, Germany
  Funding: Supported by German Research Foundation through SFB/TR 16.
At the Electron Stretcher Facility ELSA of Bonn University, an upgrade of the maximum stored beam current from 20 mA to 200 mA is planned. The storage ring operates applying a fast energy ramp of 4 GeV/s from 1.2 GeV to 3.5 GeV. The intended upgrade is mainly limited due to the excitation of multibunch instabilities. As a countermeasure, we succesfully commissioned state-of-the-art bunch by bunch feedback systems in the longitudinal and the two transverse dimensions. First results concerning the commissioning of the systems as well as the operation during the fast energy ramp will be presented. In particular, the performance while controlling the motion of every single bunch, especially in controlled bunch cleaning, will be discussed.