Neutron Technologies ( Paper Ii )

Neutrons pass relatively easily through matter and have been used successfully to interrogate the earth for bulk presence of elements, most notably those indicating petroleum. Applying these technologies to explosive detection is challenging because the “bulk” one is looking for can be as small as 100 g or less. The signals from 100 g of material are dwarfed by the background from the rest of the nearby earth and even by cosmic rays. To date, performance at confirming the presence of small amounts of ordnance is poor, even with dwells as long as 10 minutes over areas smaller than a half square meter. This is in part because of variations in the background signal over short distances on the earth’s surface, which can either mask or mimic the ordnance signal.