GROUND ROUGHNESS CALCULATIONS FOR FALLOUT GAMMA RAYS.
RADIATION RESEARCH ASSOCIATES INC FORT WORTH TEX
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A study was made of four models for calculating the effect of ground roughness on the gamma-ray energy and angular distribution in air above a fallout field. One model, called the buried-source model, assumes that a uniform thin layer of soil covers the fallout with the thickness of the layer corresponding to the degree of ground roughness. Another, called the mixed-source model, assumes that the fallout is mixed with a thin layer of soil. A third model, called the collimated-source model, assumes that the fallout is deposited on a smooth ground surface but that the gamma-ray emission is constrained to certain angular sectors. The last model, called the furrowed-surface model, assumes that the fallout is distributed over a ground surface which has uniform concentric circular furrows. Calculations of the energy and angular distributions of the uncollided and the singly scattered fluxes three feet above sources with one or more energies were performed using each of the models. Comparisons with measured data and consideration of the convenience of application indicate that the buried- and mixed-source models are preferable to the other two. The results indicate that the magnitude and the angular distribution of the uncollided flux is strongly influenced by ground roughness. The singly scattered flux, which can actually be increased by ground roughness, is much less sensitive to ground roughness than is the uncollided flux. Author
- Radioactivity, Radioactive Wastes and Fission Products