Demonstration of a new CLLBC-based gamma- and neutron-sensitive free-moving omnidirectional imaging detector

Abstract: We have developed a CLLBC-based gamma- and neutron-sensitive multi-channel omnidirectional imaging detector, suitable for handheld or vehicle-borne operation and capable of quantitative radiation mapping in 3D. The system comprises 62 CLLBC modules in an active-masked configuration, and is coupled to a Localization and Mapping Platform (LAMP) suite of contextual sensors that provides a 3D map of the environment. The contextual and radiation data is combined using Scene Data Fusion (SDF) methods to better inform the reconstruction of the source radiation distribution from variations in the measured counts as the detector moves throughout the 3D environment. Here, we first present benchtop-scale characterization studies for both the neutron and gamma ray channels. In tandem, we present Geant4 simulations of both the single-crystal and full-system detection efficiencies over the omnidirectional field of view, and compare against validation measurements. We then demonstrate the imager's capabilities in a variety of different scenarios, ranging from free-moving handheld simultaneous measurements of Cs-137 and Cf-252 to more challenging motion-constrained or static measurement scenarios. In several of these scenarios we also demonstrate how the full omnidirectional multi-crystal responses markedly improve the reconstruction quality. The imager is therefore a promising system for conducting simultaneous gamma and neutron radiation measurements in applications such as homeland security, contamination mapping, and nuclear decommissioning.