High-resolution scintillation spectrometers for neutron-activation analysis

The non-destructive assay of materials through neutron-activation analysis requires the use of gamma-ray detectors which are both sensitive up to ∼11MeV and able to provide an adequate spectral-resolution to identify the range of materials of interest to the user. However, in many such applications, it is not practical to use a cooled HPGe spectrometer and in a number of currently available systems, the manufacturers offer a variety of detector types appropriate to their particular type of neutron source and the range of elements that they wish to identify in the material to be analysed. In this paper, we examine the impact that our recently-developed spectrum-processing technology can have when applied to a range of NaI(Tl) and BGO spectrometer sizes. This information is useful in assessing which detector option is the most appropriate for a particular NAA application. The improved energy-resolution and lower cost of a NaI detector must be traded-off against the better stopping power of BGO and its poorer light-yield. In this paper we present results from NaI(TI) and BGO detectors with sensitivities at high energies up to 5 times that of a standard 5×6" NaI detector.