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Proceedings Paper

Forming images with thermal neutrons
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Paper Abstract

Thermal neutrons passing through air have scattering lengths of about 20 meters. At further distances, the majority of neutrons emanating from a moderated source will scatter multiple times in the air before being detected, and will not retain information about the location of the source, except that their density will fall off somewhat faster than 1/r2. However, there remains a significant fraction of the neutrons that will travel 20 meters or more without scattering and can be used to create an image of the source. A few years ago, a proof-of-principle "camera" was demonstrated that could produce images of a scene containing sources of thermalized neutrons and could locate a source comparable in strength with an improvised nuclear device at ranges over 60 meters. The instrument makes use of a coded aperture with a uniformly redundant array of openings, analogous to those used in x-ray and gamma cameras. The detector is a position-sensitive He-3 proportional chamber, originally used for neutron diffraction. A neutron camera has many features in common with those designed for non-focusable photons, as well as some important differences. Potential applications include detecting nuclear smuggling, locating non-metallic land mines, assaying nuclear waste, and surveying for health physics purposes.

Paper Details

Date Published: 10 January 2003
PDF: 11 pages
Proc. SPIE 4784, X-Ray and Gamma-Ray Detectors and Applications IV, (10 January 2003); doi: 10.1117/12.455693
Show Author Affiliations
Peter E. Vanier, Brookhaven National Lab. (United States)
Leon Forman, Ion Focus Technology (United States)

Published in SPIE Proceedings Vol. 4784:
X-Ray and Gamma-Ray Detectors and Applications IV
Ralph B. James; Edwin M. Westbrook; Roger D. Durst; Larry A. Franks; Arnold Burger; Edwin M. Westbrook; Roger D. Durst, Editor(s)

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