Pulsed-Neutron Die-Away Experiments for Plastics and Neutron Thermal Scattering Laws

Pulsed-neutron die-away (PNDA) experiments can be useful benchmarks to validate neutron thermal scattering laws (TSLs). The experiment uses a generator impinge short (∼10 −4 s), mono-energetic pulse on target sample. After the pulse, population within sample moderates and reaches equilibrium with fundamental spatial mode characteristic decay-time eigenvalue. eigenvalue extracted from experimental measurements of flux used as an integral parameter in validation. For certain materials geometric configurations, is heavily influenced by only material. that reason, PNDA have higher sensitivity TSLs than commonly available critical experiments. Herein, we present results for series new conducted at Lawrence Livermore National Laboratory plastic materials, e.g. high-density polyethylene Lucite. We compare parameters simulated report trends biases. evaluate bias different Monte Carlo transport codes (MCNP6.2 Mercury) show no significant differences between two codes.