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Proceedings Paper

Combining spatially and energy-resolved CdZnTe detectors with multiplexed collimations to improve performance of x-ray diffraction systems for baggage scanning
Author(s): J. Tabary; M.-C. Gentet; O. Monnet; C. Paulus; G. Montémont
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Paper Abstract

X-ray diffraction (XRD) is proven to be an effective technique for baggage screening, as it can reveal inter- and intramolecular structural information of any solid substances (mostly polycrystalline), but also of liquids, aerosols and gels. The introduction of 2D pixelated energy resolved detectors, such as CdZnTe detectors, makes now possible the development of Energy Dispersive XRD (EDXRD) systems able to perform rapid in situ 3D baggage scanning. However, the EDXRD technique requires to fix the scattering angle to few degrees with very thick collimations, which induces lack of sensitivity and spatial resolution. It is then a question of proposing technological, architectural and algorithmic solutions to improve and find the best compromise between spatial resolution, power of discrimination and inspection speed. The CEA-LETI has designed CdZnTe based energy resolved detectors in which some specific detector-level signal processing are implemented to optimize both energy and spatial resolution thanks to subpixel positioning. Subpixel positioning enables to significantly improve both angular and spatial resolution in an EDXRD system. We implemented an EDXRD system using such a detection module coupled to a multiplexed secondary collimation, in which each physical pixel inspects the object at 4 or 5 different points. The sensitivity is more than four times better compared to a parallel collimation. Some specific iterative inversion algorithms reconstruct the diffraction signatures of the materials, even when they are close together as inside a baggage. Material discrimination performance limits were explored for several objects scenarios and various levels of photon statistics.

Paper Details

Date Published: 14 May 2019
PDF: 10 pages
Proc. SPIE 10999, Anomaly Detection and Imaging with X-Rays (ADIX) IV, 109990U (14 May 2019); doi: 10.1117/12.2518871
Show Author Affiliations
J. Tabary, Univ. Grenoble Alpes (France)
CEA-LETI (France)
M.-C. Gentet, Univ. Grenoble Alpes (France)
CEA-LETI (France)
O. Monnet, Univ. Grenoble Alpes (France)
CEA-LETI (France)
C. Paulus, Univ. Grenoble Alpes (France)
CEA-LETI (France)
G. Montémont, Univ. Grenoble Alpes (France)
CEA-LETI (France)

Published in SPIE Proceedings Vol. 10999:
Anomaly Detection and Imaging with X-Rays (ADIX) IV
Amit Ashok; Joel A. Greenberg; Michael E. Gehm, Editor(s)

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