Atomic fraction analysis of compound materials by attenuation of white pulsed fast neutrons

Attenuation measurements of white pulsed fast neutron for carbon, liquid oxygen, and liquid nitrogen have been carried out and compared with Monte Carlo simulations by using the MCNPX code. The resonance peaks were analyzed and sorted to identify basis elements of C, N, and O in the neutron attenuation spectrum. The transmittances from the measurements and from the simulations, were utilized to deduce the atomic ratios of dry ice, sugar, polyurethane, and nitroglycerin. To obtain the atomic ratios of blind materials with finite thicknesses, we determined the dependences of the effective cross sections of the basis elements on the sample thickness.