Buying a Better Landmine Detector

by Dr. Jim Jury

The world's problem with antipersonnel landmines persists. It has been estimated by a variety of sources (including agencies of the United Nations) that the number of deployed antipersonnel landmines is between 50 and 110 million worldwide. The wide range of these estimates is, by itself, a matter of concern as the data are unreliable and sketchy.

The mines are located mainly in a few dozen countries (Cambodia, Kosovo, Sudan) but they can be found in 68 countries. Some 26000 persons are killed or maimed yearly, many of whom are children. Animals, wild and domesticated, are also injured.

The problem of landmines is being addressed by many governments and humanitarian agencies. However, present mine-clearing techniques result in about one casualty per 400 mines cleared. Approximately 400 000 mines are cleared per year (at an average cost of over $1000 per mine) but in some years in some trouble spots, many more are deployed. Some mines which have been placed in mapped fields, are moved by natural forces such as Hurricane Mitch in Central America last autumn, when many mines were washed down flooding rivers.

A solution to this global humanitarian problem was proposed by Foreign Affairs Minister Lloyd Axworthy acting for the Government of Canada. Several years of effort resulted in the Ottawa Treaty on the banning and clearing of landmines. This treaty came into effect in February 1999 and has been now ratified by more than 120 nations [with a few notable exceptions]. This treaty commits the signatories to the removal and destruction of the deployed landmines within a period of 10 years. The costs are expected to be more than several hundred billion dollars.

The problem is that this 10 year goal might not be even partially realized. Present techniques for the detection of mines, although very thorough and efficient [96% is the minimum detection efficiency now in place at the UN], they are VERY SLOW. The current technology consists of man-portable metal detectors swept over the suspect areas of ground. Also used are sniffer dogs, some infrared imaging and [the most dangerous] hand probing with a metal rod. Some massive ground-flailing and earth-disruption technologies have been tried but they have had little success because many mines do not detonate on the first several applications of pressure. Often a dozen or more activations are required before the mine detonates.

At Trent, our research group in applied nuclear physics, working in the Departments of Physics and Computer Studies, has been studying a new way to detect landmines which appears to be highly efficient and reasonably fast.

We have been collaborating with scientists at the University of Toronto and the University of Melbourne in Australia to develop a vehicle-borne landmine detector using beams of ground-penetrating neutrons. This can speed up the process of detection by at least a factor of ten while resulting is a greatly reduced false-positive rate (where a rock or piece of metal is incorrectly identified as a buried mine which will then require removal).

The idea is based on the fact that the explosive material in landmines is made up of nitrogen (from 20 to 40% by mass). A nitrogen nucleus can capture a thermal neutron and immediately emit a high energy gamma ray. We have learned how to detect these gamma rays above the natural radiation background from the earth. We have applied ideas from diagnostic medical imaging to form pictures of the nitrogen in the buried mines.

Our experience with computer pattern recognition (gained in many years of research collaboration with engineers at Peterborough Paper Converters, an innovative local company in the paper-coating and conversion business) has allowed for the enhancement and identification of these images as the detector vehicle crosses the ground.

Finally, as a source of neutrons, we have gone to the oil and gas industry which uses small portable neutron generators for some types of drill-hole explorations. We have adapted such an accelerator as the source of the neutron beam used to scan the earth for buried mines. When this system is combined with modern ground-penetrating radar imaging systems (commercially available), the final product will represent a technology capable of achieving the Ottawa Treaty's goal of eradication of landmines by 2009.

A provisional patent for this system has been applied for here in Canada. We are presently in discussions with a number of international companies who would join with us in a partnership to develop this "proof-of-principle" detector system into a field-ready engineered product.


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Last updated April 30, 2001