FEATURE ARTICLE
Explosives Detection with Nuclear Quadrupole Resonance
An emerging technology will help to uncover land mines and terrorist bombs
Joel Miller, Geoffrey Barrall
Hidden bombs pose an enormous menace. Some are responsible for such
well-publicized atrocities as the downing of two Russian jetliners
on the same day last August. Those in the many millions of land
mines that now litter the globe garner fewer headlines on any
particular day but do far more damage overall, killing or injuring
more than 10,000 people each year. How can civilized society rid
itself of such threats? Clearly, the answer is complicated, but one
component of the solution is to devise equipment that can reliably
uncover concealed explosives before they do harm.
We have been focused on that task for many years now. Specifically,
we and our many government, academic and industry colleagues are
trying to develop the means for detecting explosive chemicals based
on a phenomenon called nuclear quadrupole resonance (NQR). This
approach offers some distinct advantages over the other options
available. For example, the ability of bomb-sniffing dogs and vapor
detectors to sense explosives is influenced by environmental factors
such as wind and ground moisture; also, these approaches can fail
with an explosive that is hermetically sealed, as is the case for
some types of land mines and could readily be arranged in a
terrorist bomb. And one of the most high-tech tactics tried so
far—sensing the nitrogen in explosives using thermal-neutron
analysis—has proved to have inadequate sensitivity and
specificity. Detection through NQR does not face these difficulties.
To understand why not, it is helpful to review the basic physics
behind this promising technique.
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