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Properties and application areas of photon counting and energy resolving digital detector arrays

  • Since a few years the direct detection of X-ray photons into electrical signals is allowed by usage of highly absorbing photo conducting materials (e.g. CdTe) as detection layer of an underlying CMOS semiconductor X-ray detector. NDT energies up to 400 keV are today also possible. The image sharpness and absorption efficiency is improved by the replacement of the unsharp scintillation layer (as used at indirect detectors) with a photo conducting layer of much higher thickness and a high voltage across it. If the read-out speed is high enough (ca. 50 – 100 ns dead time) single X-ray photons can be counted and their energy measured. Read-out noise and dark image correction can be avoided. By definition of energy thresholds selected energy ranges of the X-ray spectrum can be detected or also suppressed. This allows material discrimination by dual-energy technique or the reduction of image contributions from scattered radiation, which results in an enhanced contrast sensitivity. To useSince a few years the direct detection of X-ray photons into electrical signals is allowed by usage of highly absorbing photo conducting materials (e.g. CdTe) as detection layer of an underlying CMOS semiconductor X-ray detector. NDT energies up to 400 keV are today also possible. The image sharpness and absorption efficiency is improved by the replacement of the unsharp scintillation layer (as used at indirect detectors) with a photo conducting layer of much higher thickness and a high voltage across it. If the read-out speed is high enough (ca. 50 – 100 ns dead time) single X-ray photons can be counted and their energy measured. Read-out noise and dark image correction can be avoided. By definition of energy thresholds selected energy ranges of the X-ray spectrum can be detected or also suppressed. This allows material discrimination by dual-energy technique or the reduction of image contributions from scattered radiation, which results in an enhanced contrast sensitivity. To use these advantages in an effective way, a special calibration procedure has to be developed, which considers also time dependent processes in the detection layer. This contribution presents some of these new properties of direct converting DDAs in comparison to the conventional indirect converting detectors for fiber composites and thick walled steel pipes (up to 35 mm wall thickness). Possible new application areas of NDT will be discussed for material discrimination especially within fiber reinforced composites (e.g. CFRC und GFRC).zeige mehrzeige weniger

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Metadaten
Autor*innen:David Schumacher
Koautor*innen:Uwe Zscherpel, Uwe Ewert, Ch. Ullberg, N. Weber, T. Pantsar, K. Perez-Fuster
Dokumenttyp:Vortrag
Veröffentlichungsform:Präsentation
Sprache:Englisch
Jahr der Erstveröffentlichung:2015
Freie Schlagwörter:Direct detection; Dual-energy; Multi-energy; Photon counting; Radiographic Testing (RT)
Veranstaltung:Digital Industrial Radiology and Computed Tomography
Veranstaltungsort:Ghent, Belgium
Beginndatum der Veranstaltung:22.06.2015
Enddatum der Veranstaltung:25.06.2015
URL:http://www.ndt.net/events/DIR2015/app/content/Slides/92_Zscherpel.pdf
Bemerkung:
Geburtsname von Schumacher, David: Walter, D.
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Birth name of Schumacher, David: Walter, D.
Verfügbarkeit des Dokuments:Datei im Netzwerk der BAM verfügbar ("Closed Access")
Datum der Freischaltung:21.06.2016
Referierte Publikation:Nein
Eingeladener Vortrag:Nein
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