Fast-neutron detector developments for the TREAT hodoscope

This work describes the theoretical and experimental performances of four alternatives to the original Hornyak Button-type device that was used in the construction of the Transient Reactor Test (TREAT) Facility hodoscope. The alternatives considered differ in geometry, construction and detection materials to improve performance while decreasing some of the negative aspects of the original device. A Geant4 model of the original Hornyak Button was developed as a benchmark to validate the physics modeled, which agreed well with the reported values. The four alternatives considered were (1) a homogenized ZnS:Ag/PMMA rectangular bar outfitted with silicon photomultipliers (SiPMs), (2) a layered ZnS:Ag/PMMA rectangular bar detector also outfitted with SiPMs, (3) a microstructured neutron detector (MSND) backfilled with hydrogenous material and (4) a pressurized, organic gaseous scintillator. In two scintillation devices, SiPMs were considered as a replacement for photomultiplier tubes for greater light collection. These alternatives were considered as they each had the potential to provide better signal-to-noise ratios, reduce Čerenkov light production, increase detection efficiency, and/or improve neutron-to-gamma discrimination. At comparable lengths, the layered design has been experimentally determined to yield an efficiency of 1.3% (the Hornyak button exhibits 0.4%), while studies on the performances of the other detectors are still underway. •Novel fast-neutron detectors were developed for hodoscope applications.•Advanced ZnS:Ag devices have low Cherenkov noise and high efficiency.•Hydrogenous MSND has very high predicted efficiency.•Layered ZnS:Ag/PMMA device exhibited best overall performance.