Dresden 2014 – wissenschaftliches Programm

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MI: Fachverband Mikrosonden

MI 2: Untersuchung von kondensierter Materie mittels Positronen-Annihilation

MI 2.2: Vortrag

Montag, 31. März 2014, 10:45–11:00, MER 02

Development of a time- and position-resolving detector for 4D-AMOC — •Ulrich Ackermann, Werner Egger, Peter Sperr, Andreas Bergmaier, Christoph Greubel, and Günther Dollinger — Universität der Bundeswehr München, Institut für angewandte Physik und Messtechnik, Werner-Heisenberg-Weg 39, 85577 Neubiberg

The Pulsed Low Energy Positron System (PLEPS) at NEPOMUC at the Munich research reactor FRM2 is a powerful tool for depth resolved investigations of defects in solids via positron annihilation lifetime spectroscopy (PALS). Besides PALS two dimensional Age Momentum Correlation Measurements (2D-AMOC) are also possible where one measures the longitudinal momentum of the electron annihilating with the positron in addition with the positrons lifetime.

To measure the positrons lifetime together with the entire 3D-momentum of the electron annihilating with the positron (4D-AMOC) a pixelated Germanium detector in coincidence with a position sensitive scintillation detector will be used. The constraints for the scintillation detector are about 100 ps time resolution (FWHM) and circa 2 mm spatial resolution (FWHM) over an area of 12 cm² at gamma energies of 511 keV, respectively.

As scintillation detector we intend to use a MCP image intensifier detector coupled to a scintillator in addition with VME and NIM electronic modules and a MARaBOU/ROOT based data acquisition. First results of time resolution and position resolution with the scintillation detector setting will be presented.