Radiation Field in Air Due to Distributed Gamma-Ray Sources in the Ground.

摘要

A much more complete and detailed picture of the external environmental gamma-ray radiation field has been obtained through gamma-ray transport calculations of exposure rates, differential energy spectra, integral exposure rate spectra, and angular exposure rate distributions due to sources distributed on or in the soil half space. The radiation field is examined not only for the natural emitters K 40, U 238, and Th 232, but also for gamma rays whose energies are typical of weapons test fallout. The energy spectra and exposure rate angular distributions are shown to vary with detector height and source distribution with resulting important implications in regard to detector calibration and prediction of ground level exposure rates from aerial survey data. Exposure rate results as a function of detector height in air above the soil air interface are tabulated for various source energies and source distributions. Although the calculated results are for specific soil and air densities, soil moisture and composition, the data can easily be adapted to other soil and air conditions.