RESUMO
Short-time instrumental neutron activation analysis, with high throughput, sensitivity and accuracy without matrix interferences, can be achieved in spite of the initial high count rate from both short and long-lived nuclide activation, if the experimental conditions are optimized by the combination of techniques. Thus the initial usually high counting rate can be faced by a loss-free counting system to avoid blocking or distortion of the system. The rapid radioactive decay and the consequent low counting statistics of short lived nuclides can be compensated by source-detector distance variation during the counting period and by cyclic and cumulative activation. Matrix spectral interferences can be reduced by ion exchange before activation for selective element preseparation and by neutron spectrum optimization such as epithermal neutron activation for selective element peak enhancement.
