Journal Article

IMPULSE-2026-00023

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Coincidence Doppler Broadening Spectroscopy of the Bulk of Single Samples

Hugenschmidt, C. (Corresponding author)MLZ* ; Chryssos, L.MLZ* ; Prossinger, R.MLZ*

2025
IOP Publ. Bristol

Please use a persistent id in citations: doi:10.1088/1742-6596/3149/1/012009

Abstract: We introduce a novel isotope-based sample-source setup designed to enable bulk defect studies on single samples. By using the positron emitter 22Na (with an activity of 7 MBq), we have adapted the Coincidence Doppler Broadening Spectroscopy (CDBS) instrument at NEutron induced POsitron source MUniCh (NEPOMUC) accordingly. Unlike the conventional sandwich geometry—where the positron source is placed between two nominally identical samples—the new setup offers the great advantage that it requires only a single sample and it eliminates detection of annihilation radiation from the source or its encapsulation, thereby removing the source contribution entirely. We demonstrate the enhanced quality of CDBS spectra obtained with the new setup on single-crystalline copper, silicon, and polycrystalline aluminum, and compare these to spectra acquired using the traditional sandwich method. By eliminating the Kapton-related source contribution—commonly present in standard Positron Annihilation Spectroscopy (PAS) measurements—we obtain a clean and uncontaminated spectrum from the bulk of the samples. The comparison of these spectra with those recorded with the sandwich method enables the determination of the positron back-reflection probability.

Keyword(s): Instrument and Method Development (1st) ; Instrument and Method Development (2nd)

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Contributing Institute(s):

1. NEPOMUC (NEPOMUC)

Experiment(s):

1. NEPOMUC: Neutron induced positron source munich (SR11)

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Database coverage:
; Nationallizenz ; SCOPUS

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