Gamma–gamma coincidence in neutron activation analysis

Abstract

Neutron activation analysis is a useful analytical technique for the determination of many nuclides. However, the resulting gamma-ray spectra frequently have overlapping photopeaks, necessitating complicated peak de-convolution techniques to perform an accurate measurement. This work investigates the viability of gamma–gamma coincidence measurements of neutron activation analysis samples for the determination of ⁷⁶As, ¹⁶⁰Tb, and ¹⁶⁹Yb to improve peak de-convolution and significantly lower the background. It is shown that these nuclides can be better determined using gamma–gamma coincidence measurements as opposed to single detector measurements. Comparisons are shown between the single channel and coincidence-gated spectra to demonstrate the de-convolution improvements achieved with coincidence gating. Additionally, a quality assurance protocol has been developed using ²²⁶Ra and ¹⁵²Eu to ascertain that the coincidence electronics are set up properly. This protocol quantitatively demonstrates the capability of this system to discriminate between true coincidence and noncoincident events.