Homogeneous and Multilayered Shields for Neutrons and Gamma-Rays

Abstract

Measurements were carried-out to compare the attenuation properties of homogeneous shields and shields of two layers and three layers for fast neutrons and total gamma rays. These were performed by measuring the fast neutron and total gamma-ray spectra behind homogeneous shields of magnetite–limonite, ilmenite–ilmenite and magnetite–magnetite concretes. The two layers assembly consists of iron and one of the above mentioned concretes, while the three layers shield consists of water, iron and one of the previously mentioned concretes. All measurements were carried-out using a neutron-gamma spectrometer with stilbene scintillator coupled to a fast photomultiplier tube. Separation between pulses of recoil protons and recoil electrons was achieved by a pulse shape discrimination technique. The obtained data are presented in the form of neutron and gamma spectra measured behind homogeneous shields and shields of two layers and three layers. The spectra measured behind homogeneous shields were used to derive the total macroscopic cross-sections for neutrons and the total attenuation coefficients for total gamma rays.