Dresden 2020 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 52: Poster Session - New Methods: Experiments
O 52.3: Poster
Dienstag, 17. März 2020, 18:15–20:00, P2/1OG
Low Energy Positron Beam for Near-Surface Doppler-Broadening Spectroscopy — •Lucian Anton Joshua Mathes, Sebastian Vohburger, Vassily Vadimovitch Burwitz, and Christoph Pascal Hugenschmidt — Physics Department E21 and Heinz Maier-Leibnitz Zentrum (MLZ), Technische Universität München
A new positron lab beam setup has been constructed for low energy Doppler-broadening experiments aimed at examining near-surface defect structures. Positrons are provided by a 22Na source, then moderated in a thin tungsten foil from which they are guided to the sample chamber by a system of longitudinal and transverse magnetic fields. The positrons are accelerated electrostatically by a potential difference applied between moderator and sample to a kinetic energy from a few electronvolts up to 30 keV. Inside the UHV chamber the positron beam is focused onto the sample by an electrostatic single lens. This setup is intended to complement the positron instrument suite at NEPOMUC and expands capabilities in the field of defect studies close to the surface layer. First experimental results on oxides will be presented.