THE DEVELOPMENT OF A THERMAL-NEUTRON ACTIVATION (TNA) SYSTEM AS A CONFIRMATORY NONMETALLIC LAND MINE DETECTOR

In order to detect and locate buried landmines for peacekeeping, the C anadian Department of National Defence (DND), under the Improved Landm ine Detection Project, is developing a vehicle-mounted. two-phase mine detection system. The first phase constitutes a suite of detectors us ed to indicate the possibility of a mine at a particular location (to +/-30 cm in accuracy). In the second phase a Thermal Neutron Activatio n (TNA) system is used to confirm the presence of explosives via detec tion of the 10.83 MeV gamma-ray associated with nitrogen decay. The TN A system developed for this uses a 100 mu g Cf-252 neutron source surr ounded by four 3 '' x3 '' NaI(Tl) detectors. Combining the use of stat e-of-the art radiation transport codes for design, judicious choice of specialized shielding materials and development of high-rate, fast-pu lse processing electronics, has led to a system which can; (i) confirm the presence of all surface- or lightly-buried anti-tank mines in a f ew seconds to a minute (depending on mass of explosive), (ii) confirm the presence of anti-tank mines down to 20 cm depth in less than 5 min utes, (iii) confirm the presence of large (>100 g nitrogen) anti-perso nnel mines in less than five minutes, (iv) operate in adverse climatic conditions. These results have been verified in field trials and the system is due to be fielded in 1999.