Neutron detectors play an essential role in Non-Destructive Assay systems for plutonium measurement, such as those that will be required to be installed at J-MOX. 3He is widely used in neutron detectors due to its outstanding γ-ray rejection properties. Recently, a world-shortage of 3He has led to renewed interest in systems based upon 10B and even 6Li. However, what all these systems lack is an ability to detect fast neutrons: the neutrons emitted by plutonium must be slowed down to energies in thermal equilibrium with their surroundings.
The Mixed Field Analyser (MFA) produced by Hybrid Instruments is a small, portable instrument that performs real-time neutron/gamma discrimination of scintillator pulses for direct input into a data acquisition and analysis system. This instrument has been evaluated by the IAEA, at its Headquarters in Vienna and then at the PPFF facility in Japan, and has been found to offer superior performance to any other development in fieldable neutron detector pulse shape discrimination (PSD). The UK Support Programme was requested to enable its further development. This report provides details of the developments subsequently undertaken.
The outcome of the task was the successful testing of the only multichannel digital processing system for fast scintillators which interfaces directly to the IAEA shift register system for neutron coincidence counting. As such, the Agency has requested further development, leading to a prototype measurement instrument, during 2012/2013.