b'Proton Recoil EffectResearch to understand the physics of fast neutron scintillator screens lays the on Light Output in Fastfoundation for improved fast neutron imaging to help advance nuclear fuel Neutron Scintillators development.F ast neutron imaging has important implications for nuclear fuel development. Fast neutron imaging has thus far been limited to a poorer spatial resolution to ensure the scintillator screen outputs enough photons to render an image.This project performed a parametric study to inform production of fast neutron TOTAL APPROVED AMOUNT:scintillator screens that provide improved spatial resolution. The study consisted $120,000 over 1 year of custom fast neutron scintillators that isolate the effects of the converter and PROJECT NUMBER:phosphor by using high-density polyethylene as a neutron converter and various 20A1047-029 phosphors to produce scintillation photons. The fast neutrons interact with the high-density polyethylene to create recoil protons, which then interact with the phosphor PRINCIPAL INVESTIGATOR:material to produce visible light.William ChuirazziAdditionally, this project studied the underlying physical mechanisms that generate CO-INVESTIGATORS: fast neutron scintillation to solve an apparent disagreement between common Aaron Craft, INL theory and widespread experimental measurements. Literature describes the range Burkhard Schillinger,of a recoil proton in fast neutron scintillators to be ~50-300 m. Recoil protons Technical University of Munich created from the interaction of the materials with INLs Neutron Radiography Reactors beamline have an energy around 1-4 MeV. Therefore, the number of recoil protons should increase for high-density polyethylene thicknesses up to the range of the recoil protons (e.g., 50-300 m) but level off after for thicker high-density polyethylene. In initial testing, however, a fast neutron scintillator with high-density polyethylene thickness varying from 0.25-3.0 mm demonstrated an increase in light output for thicknesses up to the maximum thickness of 3 mm, well beyond the 50-300 m range of the proton recoil.This research: (1) advances the study of the hypothesis that the current understanding of proton recoils light output in fast neutron scintillators is incomplete and that proton build-up in high-density polyethylene causes it to act as an amplifier that produces a higher light output in fast neutron scintillators; (2) provides for experiments and analysis toward the early determination of the utility of optimized fast neutron scintillator composition; and (3) supports the conception and preliminary technical analysis of the experimental high-resolution fast neutron scintillator screens.38'