Among the multielement methods of industrial analyses the neutron activation analyses takes a special position. The method is able to penetrate even thick layer samples and covers whole mass flows online, like on conveyor belts. The handling of this process is simplified by the use of the so called neutron-generators to the previously used radioisotope neutron sources. Neutrons are produced only on demand; the neutron production can be switched of electrically. The output of neutrons is kept constant over the life of the tubes. A new technique of pulsed excitation allows the reduction of undesired components of analytical gamma-rays. In practice a neutron source is installed beyond the belt and if there are some corresponding gamma-detectors above, the whole amount of the mass flow can be determined and controlled.With increasing particle sizes the tunnel height can be a problem because the distance from main sample to detector influences the performance of the spectrometer.
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