Fast x-ray scatter ratio method for security screening applications

Sharon M. McDaid; J. A. Hunt; Malcolm J. Cooper; Geoffrey L. Harding

doi:10.1117/12.219606

15 September 1995 Fast x-ray scatter ratio method for security screening applications

Sharon M. McDaid, J. A. Hunt, Malcolm J. Cooper, Geoffrey L. Harding

Proceedings Volume 2511, Law Enforcement Technologies: Identification Technologies and Traffic Safety; (1995) https://doi.org/10.1117/12.219606
Event: European Symposium on Optics for Environmental and Public Safety, 1995, Munich, Germany

Abstract

Potential security screening applications of a novel fluorescent x-ray source are discussed. The instrument incorporates a secondary tantalum target within the tube head and its output energy spectrum shows only the Ta fluorescence lines superimposed on a smooth, low, background. Output radiance for optimum operation is 5.9 X 10⁹ photons s^-1sr^-1mm^-2. Densitometry measurements were made on the sample volume formed by the overlap of the highly collimated primary and scattered beams and the ratio of the elastically to inelasticity (Compton) scattered signal was found. This ratio varies approximately as the square of the atomic number and its use reduces errors due to attenuation and geometry. The two main limitations of the ratio method are statistical noise and systematic effects such as multiple scattering and self-attenuation of the primary and scattered beams by the sample. These can be minimized by employing a forward scattering geometry and using a K edge filter to separate the small angle elastically and Compton scattered signals. The feasibility of the use of cheap scintillation detectors in conjunction with filters as opposed to more expensive energy dispersive detectors is demonstrated for low density materials and the implications for contraband detection discussed.

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Sharon M. McDaid, J. A. Hunt, Malcolm J. Cooper, and Geoffrey L. Harding "Fast x-ray scatter ratio method for security screening applications", Proc. SPIE 2511, Law Enforcement Technologies: Identification Technologies and Traffic Safety, (15 September 1995); https://doi.org/10.1117/12.219606

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KEYWORDS

Scattering

Compton scattering

Photons

Sensors

Tantalum

Laser scattering

X-rays

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