Analysis of a Neutron Radiograph and the Atomic Fractions by Fast Neutron Attenuation

Photo-neutrons produced by 2-GeV incident electrons bombarding a Pb or a Bi target have been made to interact with graphite, ammonium nitrate, C-4, and sugar samples. Neutrons with and without blind materials have been detected by using NE-102 plastic scintillator detectors (2.4 cm x 2.4 cm x 5 cm) arrayed in a 17 x 17 square with a total number of 289 detectors in the simulation. Atomic ratios of a sample were obtained by unfolding the transmittances with the elemental effective cross sections at the specific detectors, which apparently show the shape of the testing material.. Atomic fractions were compared with the theoretical values from the molecular formular. The atomic fractions and radiographs obtained by 40-MeV incident electron beam were compared with the results obtained by using photo-neutrons from a 2-GeV incident electron beam through a simulation with the MCNPX code.