In the article on the evolving battlefield by John S. Foster and Larry D. Welch (Physics Today, December 2000, page 31)I was pleased to see mention of landmine detection using nuclear quadrupole resonance (QR) spectroscopy, 1 a technology that shows great promise. In four DARPA-sponsored blind field tests conducted last year, including one in Bosnia, QR-based systems detected and located all of the mines with no false alarms.
Those demonstrations represent a significant increase in performance over systems in current use. The main difficulty in landmine detection has been the high rate of false alarms, not detection sensitivity per se. Current systems yield a great many false alarms for every mine detected, which leads to wasted time digging up metal debris or even rocks. Time thus spent increases stress fatigue, mistakes, and potential exposure to hostile forces. The compound specificity of QR, mentioned in passing by Foster and Welch, means QR detects only bulk explosives and, thus, only true hazards.
QR technology is also being used to scan luggage, mail, and parcels for the presence of explosives; combined with other drug scanning methods, it is also capable of detecting cocaine and heroin in their various forms.
While I agree with Foster and Welch that “efficient, reliable, and affordable approaches” are required to meet the challenges, I must point out that QR detection systems are not inherently expensive. All the basic elements of such systems are contained in amateur radio transceivers, which sell in quantity for considerably less than $5000.
