Iron Polyethylene Combination for Shielding of 14 MeV Neutrons

The best way to a chive shielding of 14 MeV neutrons was investigated.The idea is to thermalize as many neutrons as with a given shielding thickness.Since hydrogenous material is not efficient for thermalization of MeV neutrons, the neutrons are first slowed down with iron to energy rang where hydrogen is more efficient for thermalization.Layers of iron and polyethylene of various thicknesses that add up to 20 cm were investigated and it was found that a composition of 10 cm of iron before 10 cm of polyethylene gives the highest number of thermal neutrons.The fast neutron flux leading out of the shielding is decreasing continuously with increasing iron thickness