Use of very high output 14-MeV neutron generators for rock and ore sorting

The use of 14-MeV neutrons to determine the major and minor constituents in rock using 14-MeV neutron generator systems with total yields of the order of 1010n/s has been an established technique for 15 years. However, a programme of development is now underway at the Sandia Laboratories which may result in the availability of a very high output steady-state 14-MeV generator producing neutrons at a level of 5x1012 to 5x1013n/s. Clearly higher sensitivity and precision will be possible due to improved count-rates and peak-to-background ratios. In several cases the measurement sensitivity needed for trace analysis will be obtained with reactions of lower cross-section but yielding reaction products of distinctive decay characteristics (half-life, gamma-ray energy) and fewer interferences. For some elements, high sensitivity will be attainable through the use of short-lived nuclides. A series of elements with too low specific activities under present activation conditions will be accessible at trace levels via nondestructive determinations; these include: B, S, As, Nb, Pd, Sn, Lu, Ta, Ir, Pt, Au, Hg and Pb. Applications of the high-flux 14-MeV neutron generator to geological and geochemical analyses are discussed. (author)