Fast neutron resonance radiography with full time-series digitization

Fast neutron resonance radiography (FNRR) is an emerging technology for resolving the in-depth elemental composition of samples. It relies on the modification of a broad neutron energy spectrum transmitted through the sample due to resonant features in its neutron interaction cross-sections. FNRR has yet to reach widespread use because of its high cost and the large size of high-flux neutron generators, and of the radiography setup. The realization of compact neutron generators based on high-intensity lasers motivate reducing the size of FNRR setups from 10- to few-meter scale. The challenge is posed by the fact that for a fixed temporal resolution, a shorter neutron flight path corresponds to reduced resolution in energy. Here we address this challenge by recording the full neutron-time-of-flight time-series for each and every pixel. The rich spectral information reveals unique neutron interaction features, even with low energy resolution. We present the characterization of a proof-of-principle detector, using a spallation neutron source. The results are used to assess the requirements for a fully applicable neutron imager for FNRR applications.