51 research outputs found
The Cyber Security Transparency Centre in Brussels
Original text published in German: Christoph Hugenschmidt, Wie Huawei Cybersecurity praktiziert und wie transparent das wirklich ist - Ein Besuch im Cyber Security Transparency centre in Brüssel, in Marc Furrer (Ed.), Selbstbestimmt. Sind Souveräne Kommunikationsnetze in der Schweiz möglich?, Stämpfli Verlag, Bern, 2022, 89-95. Published in English with permission of the publisher
CDBS: Coincident Doppler-broadening spectrometer
The CDBS, operated by the Technische Universität München, located at NEPOMUC, allows the detection of open volume defects and their chemical surrounding. Defect distributions can be imaged in 3D by lateral scanning with the energy variable positron beam
PAES: Positron annihilation induced Auger electron spectrometer
Positron annihilation induced Auger electron spectroscopy (PAES) is a newly developed application for surface studies with high elemental selectivity and exceptional surface sensitivity. The instrument is operated by the Technische Universität München and is located at NEPOMUC
NEPOMUC: Neutron induced positron source Munich
NEPOMUC, operated by the Technische Universität München and the Universität der Bundeswehr München, provides a high-intensity low-energy positron beam for applications in solid state and surface physics as well as for fundamental research in nuclear and atomic physics. The intensity amounts to > 109 moderated positrons per second at a beam energy of E = 1 keV
Absolute fraction of emitted Ps determined by GEANT4 supported analysis of gamma spectra
The fraction of positronium (Ps) emitted from a surface of a germanium single
crystal at high temperature is usually assumed to approach unity at zero
positron implantation energy. In the experiment, however, the determination of
the absolute Ps fraction is not straight forward since recording a reference
spectrum with Ps formation remains demanding. We use GEANT4-simulated
detector responses to and radiation sources mimicking
positron and Ps annihilation inside the (coincidence) Doppler-broadening
spectrometer at NEPOMUC, FRM II, in order to derive a reliable value for the Ps
fraction reemitted from a Ge(100) target heated close to its melting point.
Analysis of the measured spectra by fitting the simulated spectra shows an
absolute value of maximum Ps formation, contradicting the
assumption
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