Optimising a compact dual-particle imager with a novel combination of organic and inorganic scintillators

This work discusses the process of optimising the performance of a compact dual-particle imager with a fast response time of 60 s and a signal processing time of 60 s. The imaging concept relies on a radiation scattering technique with a neutron-scattering sub-system, a Compton-scattering sub-system and a thermal neutron absorption layer. The enhanced design proposed here reduces the signal processing time compared to earlier work. The time lagging occurs mainly during neutron-gamma discrimination within the neutron scattering sub-system. Hence, the optimisation here which mainly targets investigating two promising dual particle detectors EJ-212 and EJ-276D as possible replacement for the EJ-204 in the original device. The results indicated that EJ-212 and EJ-276D offer similar elastic scattering and escape probabilities of neutrons at energies less than 100 keV. At energies higher than 500 keV, the elastic scattering probabilities increase with thickness, reaching a maximum around 24 % in both detectors. As for gamma-ray photons, the results showed that the two detectors have similar total mass attenuation coefficients. Further investigation showed that EJ-212 exhibits a higher Compton scattering cross-section with respect to EJ-276D. Additionally, results show that EJ-276D maintains the imager intrinsic efficiency while offering built-in neutron-gamma discrimination abilities.