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HK: Fachverband Hadronen und Kerne

HK 67: Poster Session

HK 67.102: Poster

Thursday, March 19, 2009, 14:00–16:00, Audi-Max

Design and setup of a trigger system for Moeller polarimetry to determine the electron beam polarisation at MAMI-C — •Peter-Bernd Otte — Institut für Kernphysik, Mainz, Germany

The "Crystal Ball (CB) Collaboration" at the "Institut fuer Kernphysik" in Mainz carries out experiments with real photons, which are produced via the Bremsstrahlung process from accelerated electrons coming from the accelerator MAMI (Mainz Microtron). In 2007 the new accelerator stage MAMI-C became operational and delivers up to 1.558 GeV in cw-mode. The energy-tagged photons induce reactions in nucleons and nuclei which are studied using the CB/TAPS 4π-calorimeter.

The helicity dependence of Moeller scattering can be used to measure the beam polarisation. To select these events in the tagging spectrometer, a specially adapted trigger system was developed. In the poster, the setup, experimental method and details of the FPGA-based trigger electronics will be presented.