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Defence R&D Canada - Suffield and Bubble Technology Industries have been developing thermal neutron activation (TNA) sensors for detection of buried bulk explosives since 1994. First generation sensors, employing an
isotopic source and NaI(Tl) gamma ray detectors, were deployed by Canadian Forces in 2002 as confirmation
sensors on the ILDS teleoperated, vehicle-mounted, multi-sensor anti-tank landmine detection systems. The first
generation TNA could detect anti-tank mines buried 10 cm or less in no more than a minute, but deeper mines
and those significantly displaced horizontally required considerably longer times. Mines as deep as 30 cm could
be detected with long counting times (1000 s). The second generation TNA detector is being developed with a
number of improvements aimed at increasing sensitivity and facilitating ease of operation. Among these are an
electronic neutron generator to increase sensitivity for deeper and horizontally displaced explosives; LaBr3(Ce)
scintillators, to improve time response and energy resolution; improved thermal and electronic stability; improved
sensor head geometry to minimize spatial response nonuniformity; and more robust data processing. This improved sensitivity can translate to either decreased counting times, decreased minimum detectable explosive
quantities, increased maximum sensor-to-target displacement, or a trade off among all three. Experiments to
characterize the performance of the latest generation TNA in detecting buried landmines and IEDs hidden in
culverts were conducted during 2011. This paper describes the second generation system. The experimental
setup and methodology are detailed and preliminary comparisons between the performance of first and second
generation systems are presented.
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