The back-scattering and attenuation of neutrons in a few types of polymers

Polymers contain mainly H and C atoms, they are therefore good moderators and attenuators for fast neutrons. Some polymers such as PVC contain other atoms like Cl which has intermediate absorption cross section value for slow and medium energy neutrons. The back-diffusion and attenuation properties in a few polymers were studied for quality control purposes. Fast neutrons from 241AM-9Be neutron source are allowed to be incident on polymer samples. None of these neutrons will get moderated and diffuse backward to the source position. The intensity of these back-diffused neutrons, measured by slow neutron detector such as BF3 counter is related to the atomic concentration. A change in density, existence of voids, impurity or change in thickness would change this intensity. The attenuation of fast neutrons by polymers was also studied. Fast neutrons were measured by neutron dosimeter which has almost a flat response to fast neutron