This invention relates to the location of nitrogen-rich materials, such as explosives, by detection of gamma rays emitted in response to capture of neutrons by such materials.
Apparatus for generating fast neutrons that are moderated and captured by nitrogen-rich materials to be analyzed from detection of resulting emission of gamma rays therefrom, is already well known as disclosed for example in U.S. Pat. Nos. 4,171,485, 4,278,885 and 4,882,121, to Marshall, von Alfthan et al. and Gremier, respectively. Use of such apparatus is however limited to the analysis of materials located in the immediate vicinity of the apparatus because of operational parameters associated therewith.
Accordingly, it is an important object of the present invention to provide a system for mapping the location of nitrogen-rich materials, buried in soil and water as embedding media, by measurement of gamma radiation emitted in response to capture of neutrons from a moving source.