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Coincident Doppler-broadening spectrometer
The Coincident Doppler-broadening spectrometer (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.
The Doppler broadening of the 511 keV annihilation line contains information of the electron momentum distribution at the positron annihilation site in the sample. Since the probability of core electron annihilation decreases in open volume defects a narrowing of the annihilation line is observed. For this reason, Doppler broadening spectroscopy (DBS) is particularly suited to detect lattice defects in a sample. DBS with the monoenergetic positron beam allows the analysis of defect profiles, energy dependent 2D imaging of defects, and defect annealing as a function of temperature. In addition, CDBS is applied in order to gain elemental information about the positron annihilation site and hence about the chemical surrounding of defects.
High-purity Ge detectors
Typical measurement times
Prof. Dr. Christoph Hugenschmidt
Phone: +49 (0)89 289-14609
Phone: +49 (0)89 289-14774
Heinz Maier-Leibnitz Zentrum. (2015). CDBS: Coincident Doppler-broadening spectrometer. Journal of large-scale research facilities, 1, A23. http://dx.doi.org/10.17815/jlsrf-1-50
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