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Limited view tomography of wood with fast and thermal neutrons

  • Neutrons are absorbed particularly by hydrogen containing materials so they can be used as a tool for visualising heterogeneous density distributions of organic materials. Penetration limits are set by the layer thicknesses and the neutron energies applied. In case of specimens with a flat shape the situation may be encountered that the object only could be penetrated in selected directions. In addition, the overall size may exceed the beam diameter and thus the viewing window if a certain region of interest should be studied by tomography without destroying the integrity of the specimen. This study shows the capabilities and limits of thermal and fast neutrons to investigate flat wooden specimens such as boards and girders by neutron tomography under such circumstances. Taking projections was impaired either by the limits of penetrability or by the total size of the object. As a consequence, projections were included for reconstruction only from a limited angular range of 90°. ItNeutrons are absorbed particularly by hydrogen containing materials so they can be used as a tool for visualising heterogeneous density distributions of organic materials. Penetration limits are set by the layer thicknesses and the neutron energies applied. In case of specimens with a flat shape the situation may be encountered that the object only could be penetrated in selected directions. In addition, the overall size may exceed the beam diameter and thus the viewing window if a certain region of interest should be studied by tomography without destroying the integrity of the specimen. This study shows the capabilities and limits of thermal and fast neutrons to investigate flat wooden specimens such as boards and girders by neutron tomography under such circumstances. Taking projections was impaired either by the limits of penetrability or by the total size of the object. As a consequence, projections were included for reconstruction only from a limited angular range of 90°. It could be shown that an approach based on the slice theorem was capable to visualise structural features along the beam directions while simply omitting the perpendicular ones without causing additional artefacts. Small samples with a thickness of up to 2 cm but several times broader could be studied with the ANTARES facility of the FRM II neutron source in Garching providing thermal neutrons while larger objects required a beam of higher energy as available in the NECTAR facility of the same institution. The fast (fission) neutrons (1.5 – 2 MeV) of this site allowed investigating an area of interest inside a girder with a cross section of 23.5 x 49 cm². Internal features such as inclusions could be detected as well as a heterogeneous density distribution in glue layers.zeige mehrzeige weniger

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Metadaten
Autoren/innen:Kurt Osterloh, Daniel Fratzscher, Mirko Jechow, T. Bücherl, B. Schillinger, A. Hasenstab, Uwe Zscherpel, Uwe Ewert
Dokumenttyp:Beitrag zu einem Tagungsband
Veröffentlichungsform:Verlagsliteratur
Sprache:Englisch
Titel des übergeordneten Werkes (Englisch):International symposium on digital industrial radiology and computed tomography (Proceedings)
Jahr der Erstveröffentlichung:2011
Veröffentlichende Institution:Bundesanstalt für Materialforschung und -prüfung (BAM)
Verlag:Deutsche Gesellschaft für zerstörungsfreie Prüfung e.V. (DGZfP)
Ausgabe/Heft:DGZfP-BB 128 (Poster 14)
Erste Seite:1
Letzte Seite:5
Freie Schlagwörter:Computed tomography; Limited angle tomography; Slice theoreme
Veranstaltung:International symposium on digital industrial radiology and computed tomography
Veranstaltungsort:Berlin, Germany
Beginndatum der Veranstaltung:20.06.2011
Enddatum der Veranstaltung:22.06.2011
URN:urn:nbn:de:kobv:b43-250663
ISBN:978-3-940283-34-4
Verfügbarkeit des Dokuments:Datei für die Öffentlichkeit verfügbar ("Open Access")
Lizenz (Deutsch):License LogoCreative Commons - Namensnennung-Keine Bearbeitung
Datum der Freischaltung:31.12.2015
Referierte Publikation:Nein
Schriftenreihen ohne Nummerierung:BAM Präsentationen