Gamma-gamma coincidence performance of LaBr₃:Ce scintillation detectors vs HPGe detectors in high count-rate scenarios

A radiation detection system consisting of two cerium doped lanthanum bromide (LaBr₃:Ce) scintillation detectors in a gamma-gamma coincidence configuration has been used to demonstrate the advantages that coincident detection provides relative to a single detector, and the advantages that LaBr₃:Ce detectors provide relative to high purity germanium (HPGe) detectors. Signal to noise ratios of select photopeak pairs for these detectors have been compared to high-purity germanium (HPGe) detectors in both single and coincident detector configurations in order to quantify the performance of each detector configuration. The efficiency and energy resolution of LaBr₃:Ce detectors have been determined and compared to HPGe detectors. Coincident gamma-ray pairs from the radionuclides ¹⁵²Eu and ¹³³Ba have been identified in a sample that is dominated by ¹³⁷Cs. Gamma-gamma coincidence successfully reduced the Compton continuum from the large ¹³⁷Cs peak, revealed several coincident gamma energies characteristic of these nuclides, and improved the signal-to-noise ratio relative to single detector measurements. LaBr₃:Ce detectors performed at count rates multiple times higher than can be achieved with HPGe detectors. The standard background spectrum consisting of peaks associated with transitions within the LaBr₃:Ce crystal has also been significantly reduced. It is shown that LaBr₃:Ce detectors have the unique capability to perform gamma-gamma coincidence measurements in very high count rate scenarios, which can potentially benefit nuclear safeguards in situ measurements of spent nuclear fuel.