|Author||Barsukov, O. A. ♦ Avzyanov, V. S.|
|Source||United States Department of Energy Office of Scientific and Technical Information|
|Subject Keyword||PHYSICS ♦ ABSORPTION ♦ BERYLLIUM ♦ CONFIGURATION ♦ COPPER ♦ CROSS SECTIONS ♦ ELASTIC SCATTERING ♦ ENERGY ♦ ENERGY RANGE ♦ GAMMA RADIATION ♦ INELASTIC SCATTERING ♦ IRON ♦ LAYERS ♦ LEAD ♦ MEASURED VALUES ♦ METALS ♦ NEUTRON SOURCES ♦ PARAFFIN ♦ PLANNING ♦ POLONIUM ♦ SCATTERING ♦ SHIELDING ♦ SLOWDOWN ♦ SPECTRA ♦ SPHERES ♦ THICKNESS ♦ VARIATIONS ♦ VESSELS ♦ WATER ♦ WEIGHT|
|Abstract||In order to determine the best shield design, a point source was placed in the center of a metal--water medium and an attempt was made to select the arrangement of layers which yielded the best results in slowing down and absorbing the neutrons and the gamma radiation while keeping the dimensions and the weight of the shield to a minimum. The scattering was taken into consideration by using the multigroup diffusion approximation of the Boltzmann equation. A 10/sup 8/ n/sec Po--Be point source placed in the center of a 30-cm radius sphere was used in the experiments. The changes in the energy spectrum of the emitted neutrons in a homogeneous, water or Fe, medium were determined. The Fe medium was found to cause a considerable softening of the spectrum; in the case of water, the 10.8to 1-Mev neutrons became the chief component of the energy spectrum. The water also slowed down effectively the neutrons with lower energies. The results indicated that it is desirable to use a complex system, consisting of hydrogenous materials such as water or paraffin and a metal, e.g., Fe, Cu, or Pb. The shielding properties of the two-layer Fe--water system were found to be superior to those of a homogeneous water system if the total thickness of 1 of the 2 layers is larger than the inversion length 1/sub inv/(25 cm). However, in the 3- to 1-Mev range in which the inelastic scattering cross section of the Fe is small and the elastic scattering cross section is still smaller, the neutrons of that energy range may be accumulated. An improved shielded container was designed on the basis of the data obtained. (TTT)|
|Learning Resource Type||Article|
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