Great progress has been made in recent years in realizing compact, laser-based neutron generators. These tabletop systems are ideal for Fast Neutron Resonance Radiography (FNRR). FNRR takes advantage of the unique neutron absorption spectra of different elements and is used in various research, industry and security applications. In FNRR, neutrons from a pulsed source of a broad energy range are transmitted through the imaged object. Multiple radiographs are taken downstream at several time intervals each corresponding to a different neutron energy bin. The different energy bins can then be correlated to specific absorption energy resonances to yield radiographs of multiple material densities in the sample.

Recording neutron time-of-flight data of each pixel with a typical sampling rate of about a GHz is beyond current technology. 

To address this challenge, we developed a proof-of-principle detector composed of 4X4 scintillating fibers coupled to Silicon photomultipliers. The time-of-flight data is recorded using a 16-channel GHz digitizer. Fielding this detector at the fast neutron beam-line at Los Alamos Neutron Science Center, we demonstrated FNRR of a few-cm thick sample.

Our results indicate that with a modest R&D effort, the detector may be extended to a high-resolution neutron imager, applicable to laser-based neutron generation setups.