A multiple time-gated system for pulsed digital gamma-ray spectroscopy

Neutron activation analysis (NAA) systems that use pulsed neutron generators (NGs) employ spectrum gating procedures to segregate nuclear processes by acquiring gamma-ray spectra separately when the generator is on (HIGH gate) and off (LOW gate). Often, the actual neutron burst lags the leading edge of the HIGH gate signal by a few μs. Thus, count rates vary not only between the on and off states of the NG, but within them as well. Recent advances in digital gamma-ray spectrometers that allowed the concurrent acquisition of data by sorting events into two separate spectra based on gate status suggested that a time-resolved analysis that further subdivided the neutron pulse cycle could obtain further information to separate gamma-rays produced by different nuclear reactions. In this paper we introduce a gating system for time-resolved NAA that is capable of concurrently acquiring as many as 16 spectra from up to 8 user-defined time intervals during each of the HIGH gate and LOW gate periods, each with all required timing and count rate information. We present the new gating system’s implementation, operation and some first experimental test results.