10-11 December 2019
Europe/Berlin timezone

The Coincident Doppler-Broadening Spectrometer at NEPOMUC

10 Dec 2019, 15:00
Marriott Conference room - Munich (Marriott)

Marriott Conference room - Munich


Berliner Str. 93 80805 München Germany
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Talk Positrons Positrons


Vassily Vadimovitch Burwitz Leon Chryssos Lucian Mathes


The capabilities of the Coincident Doppler-Broadening Spectrometer at the Neutron-induced Positron Source Munich (NEPOMUC) will be presented. In addition an overwiew of planned expansions will be given.
Two beam modes are available: standard operations provide a beam spot of $> 300\ \mu\textrm{m}$ (FWHM) and micro beam for scanning with a reduced diameter of $33\ \mu$m (FWHM). Mearsurements may either be conducted as standard Doppler-broadening spectroscopy (DBS) where the signal at each detector is treated separately or in coincident Doppler-broadening mode (CDBS) where the detectors are run as coincidence pairs. CDBS provides a greatly improved signal to noise ratio ($10^{8}$) allowing the analysis of the chemical surrundings of defect. Currently four different sample holders are available: i) a piezo x-y stage for precision 2D scanning and hence 3D defect imaging, ii) a heatable sample holder with T$_{max}=1100\ \textrm{K}$ for T dependent defect spectroscopy, iii) a cryostat with T$_{min}=40\ \textrm{K}$, iv) a device for in situ tensile tests. Ongoing improvement works include: an automated beam optimization system from which especially the micro beam mode will greatly profit. A planned increase in the number of detectors combined with an upgrade of the readout electronics, which should considerably reduce measurement times.

Primary authors

Vassily Vadimovitch Burwitz Leon Chryssos Lucian Mathes


Christoph Hugenschmidt Thomas Schmidt

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