Real-time source localisation by passive, fast-neutron time-of-flight with organic scintillators for facility-installed applications.

Fast neutron time-of-flight (ToF) has been used to characterise the location of a source of a mixed radiation field. Two EJ-309 organic scintillators and a fast, digital, data acquisition system have been used in a variety of positions to identify the location of a 252Cf neutron source inside a steel, water-filled tank. A methodology for extracting the distance between the neutron source and the neutron detector has been developed and verified with MCNP simulations. A reconstruction algorithm using the ToF data has been developed. The location of the neutron source has been estimated on this basis to be within 20 cm of its known location with a spatial resolution of ± 7.8 cm. p-values extracted from the null test hypothesis have been estimated to be 0.975 and 0.996 for experimental and simulation data, respectively. By correctly identifying the location of the source, the potential for the system to discern between scattered and unscattered neutrons is demonstrated. • Fast neutron time-of-flight data, derived from the separation of γ rays and neutrons emitted in spontaneous fission in 252Cf, have been used to identify the position of a 252Cf source. • Experimental data, derived with two organic scintillation detectors, have been compared with data from a parallel simulation-based study and are observed to converge with one another. • The technique appears to be resistant to perturbations by neutrons scattered by the surroundings. • The position of the source determined by time-of-flight agrees within uncertainties with the known source location. [ABSTRACT FROM AUTHOR]