Thermal neutron source location using a 3-D position-sensitive CdZnTe detector array

A method for the location of a far-field thermal neutron source using an array of eighteen 2 × 2 × 1.5 cm³ position-sensitive CdZnTe detectors has been proposed. The relative intensity of 558 keV ₁₁₃Cd capture γ rays emitted from the outward-facing surfaces of each detector in the array was estimated via Compton imaging. The detector response to thermal neutrons was simulated using Geant4 and stored in a response matrix. The estimated location was the least squared difference between simulated and measured detector responses. Eight measurements of a 1 Ci ²³⁹PuBe neutron source moderated by paraffin were used to demonstrate the performance of this method, which was limited by the chosen size of the system matrix and mismatch between measurement and simulation.