Positron Beam Experiments at NEPOMUC

by Christoph Hugenschmidt

Monday 5 Jul 2021, 14:30 → 15:30 Europe/Berlin

Zoom Webinar

The neutron induced positron source NEPOMUC at FRM II provides the world’s highest intensity of 109 low-energy positrons per second. In solid state physics and materials science the positron is applied as a highly mobile probe for the detection of vacancy-like defects and their chemical surrounding using (coincident) Doppler broadening spectroscopy ((C)DBS) of the positron-electron annihilation line. Our scanning positron µ-beam available at the CDB-spectrometer allows depth dependent defect spectroscopy as well as the investigation of defect distributions (“3D-Defect-Imaging”).

Within this presentation, I will first give a brief overview of the positron beam facility at NEPOMUC and various positron experiments benefitting from the high beam intensity. Then two examples will be elucidated in detail: (i) oxygen vacancies and their effect on the local transition temperature in high-Tc superconductors and (ii) vacancies and precipitates in laser beam welded age-hardened aluminum alloys.