Neutron collimator optimization for 14.1 MeV DT neutrons using Monte Carlo and Genetic algorithms.

The fast neutrons generated by Deuterium-Tritium (DT) fusion reaction have been widely applied in prompt gamma ray neutron activation analysis measurements. In this study, a multi-layer neutron collimator for DT neutron generator was developed. Genetic algorithm combined with Monte Carlo simulation was used to design a collimator made of iron, lead, graphite, and borated polyethene. Copper foil activations were conducted to determine the fast neutron flux ratios between the beam port and its nearby area and agreed well with those predicted by the simulations. The results demonstrated that a narrower beam was obtained. The fast neutron beam flux was 568 ± 14 s-1 cm-2. The neutron flux ratio of the collimator was improved by a factor of 2.36, which could provide a better neutron beam.

Optimization of an inelastic neutron scattering facility and its application on bulk metallic materials measurement.

An inelastic neutron scattering facility consisting of a DT neutron generator and a HPGe detector was used for metallic material analysis. The facility model was optimized based on Monte Carlo simulations. Performance of modified facility was tested through various metallic elements measurements. The results showed that the mass detection limits (MDL) of different elements were improved after optimization. Quantitative analyses of Fe and Cr in stainless steel sample were then conducted to evaluate the performance of alloy measurement. Calibration curves were obtained through measuring the reference samples. The contents of Fe and Cr in an unknown sample were determined by the calibration curves and the results were in good agreement with those obtained by X-ray fluorescence method.