Dresden 2014 – scientific programme

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MI: Fachverband Mikrosonden

MI 8: Poster: Microanalysis and Microscopy

MI 8.1: Poster

Wednesday, April 2, 2014, 17:00–19:30, P4

Development of a µm-positron beam for non-destructive 3D-defect imaging — •Thomas Gigl, Markus Reiner, Christian Piochacz, and Christoph Hugenschmidt — Technische Universität München, Physik-Department E21 and FRM II, 85748 Garching

Doppler broadening spectroscopy with positrons is a well-established non-destructive tool for the investigation of lattice defects in solids. The positron as a nanoprobe is highly sensitive to open volume defects, vacancy-atom complexes and atom clusters of higher positron affinity. The chemical surrounding of the annihilation site can be studied by the coincident detection of the Doppler shifted quanta. For the current project a new high resolution Coincident Doppler Broadening (CDB) spectrometer is under development at the high intensity positron source NEPOMUC (Neutron induced Positron source MUniCh) at the research neutron source FRM II. Therefore, a brightness enhancement system consisting of a Ni(100) re-moderation foil and different magnetic and electrostatic lenses have to be designed and simulated. The aim is to reach a positron beam diameter of below a few µm at the sample position for high resolution experiments. Within this contribution the new design of the spectrometer and simulations to the brightness enhancement system will be presented. Financial support provided for the improvement of the instruments PAES and CDBS (project nos. 05KI0WOB and 05K13WO1) by the BMBF is gratefully acknowledged