Fast neutron scattering analysis

The scattering of a beam of fast monoenergetic neutrons is used to determine elemental compositions of small (0.2-1 kg) samples of materials. Particular emphasis is placed on the measurement of concentrations of the elements H, C, N and O, which are the principal constituents of contraband materials, such as explosives and narcotics. Scattered neutrons are detected by liquid scintillators located at forward and at backward angles, and different elements are identified by their characteristic scattering signatures derived either from a combination of time-of-flight and pulse height measurements or from pulse height measurements alone. Atom fractions for H, C, N, O and other elements are derived from unfolding analyses based on these scattering signatures and used to identify materials. Effects of neutron interactions in surrounding materials, either in the neutron beam or between the scatterer and the detectors, can be detected and allowed for in such a way as not to interfere significantly in the identification of the scatterer. The Fast Neutron Scattering Analysis technique provides a non- intrusive method for detecting and identifying sub-kilogram quantities of contraband materials. Methods for locating the positions of small contraband items in packages of volume up to about 0.5m³ are described and a two-stage screening system for detecting contraband hidden in small packages is proposed.

Grantor dc:publisher.institution

Department of Physics

Year dc:date.issued

1998

Author dc:creator

• Buffler, Andy

Advisors dc:contributor.advisor

• Brooks, F D
• Aschman, David G

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/11427/17137

OAI identifier oai:identifier

oai:open.uct.ac.za:11427/17137