Gamma-Ray Energy and Angular Distributions Near the Air/Ground Interface from Plane Fallout and Point CO60 Sources

摘要

Monte Carlo techniques were applied in a detailed study of the gamma radiation environment three feet above the air/ground interface due to two types of gammaray sources: (1) fallout uniformly distributed on the ground surface, and (2) a Co60 point source also three feet above the ground at separation distances of 100 to 800 feet. In each case, the scattered and direct-beam fluxes were computed in each of ten receiver energy intervals between 0.04 and 3.5 Mev and eighteen equal receiver angle intervals between 0 (nadir) and 180 degrees (Zenith). All results were integrated over azimuthal angle at the receiver to reflect distribution in polar angle only. The source energy was used as a parameter in the fallout calculations and the results thus computed for each of ten different source energies may be weighted and combined to obtain data for fallout of any desired age. Comparisons of the Monte Carlo data with measured data and with other calculated data, both for fallout and for Co60 point sources, show favorable agreement. (Author)