A militarily fielded thermal neutron activation sensor for landmine detection

The Canadian Department of National Defence has developed a teleoperated, vehicle-mounted, multi-sensor system to detect antitank landmines on roads and tracks in peacekeeping operations. A key part of the system is a thermal neutron activation (TNA) sensor which is placed above a suspect location to within a 30 cm radius and confirms the presence of explosives via detection of the 10.835 MeV gamma ray associated with thermal neutron capture on N-14. The TNA uses a 100 mu g Cf-252 neutron source surrounded by four 7.62 cm x 7.62 cm NaI(TI) detectors. The system, consisting of the TNA sensor head, including source, detectors and shielding, the highrate, fast pulse processing electronics and the data processing methodology are described. Results of experiments to characterize detection performance are also described. The experiments have shown that anti-tank mines buried 10cm or less can be detected in roughly a minute or less, but deeper mines and mines significantly displaced horizontally take considerably longer time. Mines as deep as 30 cm can be detected for long count times (1000 s). Four TNA detectors are now in service with the Canadian Forces as part of the four multi-sensor systems, making it the first militarily fielded TNA sensor and the first militarily fielded confirmation sensor for landmines. The ability to function well in adverse climatic conditions has been demonstrated, both in trials and operations. Crown Copyright (c) 2007 Published by Elsevier B.V. All rights reserved.