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Proceedings Paper

Finding concealed high atomic numbered materials hidden in cargo containers using dual-energy high-energy x-rays from a linear accelerator with the unique signature from photofission
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Paper Abstract

The Dual Energy X-ray technique employs two X-ray projection images of an object with X-ray energy spectra at a low X-ray energy and a high X-ray energy. The two energies are both high enough to penetrate all cargoes. The endpoint energies for low and high will be approximately 5-6 MeV and 8-9.5 MeV respectively. These energies are chosen such that pair production is the dominant energy loss mechanism for the high energy mode. By defining the ratio of the transmitted X-ray photon R = Thigh/Tlow it can be shown that there is a difference in the ratio that will permit the detection of materials that are significantly higher in atomic number than the low to mid atomic numbered elements that normally appear in the stream of commerce. This difference can be used to assist in the automatic detection of high atomic numbered materials. These materials might be a WMD or dirty bomb. When coupled with detectors that can observe the delayed signature of photon induced fission a confirmation of a WMD may be made. The use of the delayed photons and neutrons from Photofission can confirm the presence of Special Nuclear Materials (SNM). The energy required to induce fission in SNM by a photon is approximately 6 MeV with the maximum fission production rate from X-ray photons in the energy range of 12-15 MeV.

Paper Details

Date Published: 10 May 2006
PDF: 12 pages
Proc. SPIE 6201, Sensors, and Command, Control, Communications, and Intelligence (C3I) Technologies for Homeland Security and Homeland Defense V, 62010E (10 May 2006); doi: 10.1117/12.666078
Show Author Affiliations
James E. Clayton, Varian Medical Systems (United States)
Paul Bjorkholm, Varian Medical Systems (United States)


Published in SPIE Proceedings Vol. 6201:
Sensors, and Command, Control, Communications, and Intelligence (C3I) Technologies for Homeland Security and Homeland Defense V
Edward M. Carapezza, Editor(s)

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