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HK: Fachverband Physik der Hadronen und Kerne
HK 39: Instrumentierung - Poster
HK 39.48: Poster
Mittwoch, 23. März 2011, 14:00–16:00, Foyer Chemie
Beam test of a specialized detection system for laser spectroscopy measurements at the ESR at GSI — Volker Hannen1, Raphael Jöhren1, Matthias Lochmann2,3, Rubén Lopéz Coto1, •Jonas Mader1, Wilfried Nörtershäuser2,3, Rodolfo Sánchez3, and Christian Weinheimer1 — 1Institut für Kernphysik, Universität Münster — 2Institut für Kernchemie, Universität Mainz — 3GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt
An experimental comparison between hyperfine transitions in H- and Li-like heavy ions of the same isotope permits precise tests of QED in extremely strong electromagnetic fields. While the transition energy of 209Bi82+ has been determined in previous laser spectroscopy experiments, the transition in 209Bi80+ is challenging and still under investigation, because of the long transition wavelength (λ ≈ 1555 nm) and the very low signal rate due to a long lifetime of the HFS state of 82 ms.
At the ESR the wavelength of forward emitted photons is shifted to 640 nm. At this wavelength the photons can be detected by a very sensitive low noise PMT. To collect the forward emitted photons a movable parabolic mirror is placed around the ion beam. First beam tests with the mirror which has a 3 cm wide slit for passage of the ions, have proven that, except for interactions with the beam halo, the setup does not decrease the life time of the stored ions.
The poster presents the actual setup of the mirror system, as well as first beam tests serving as a prove of principle.
This work is supported by BMBF under contract number 06MS9152I.