Monte Carlo Calculation of Gamma-Ray Flux Density Due to Atmospheric Radon Daughters

The γ-ray flux densities at the ground surface emitted from radon daughters in the overhead air have been calculated by means of the Monte Carlo method to investigate the effect of those on environmental γ-rays and to make a comparison with measured values It has been made clear that radon daughters distributed in an atmospheric hemisphere of the 500 m radius cause a variation in the γ-ray flux density at the detector near ground surface The amount of this variation has been calculated to be more than 10% of the background level Using the results obtained, γ-ray flux densities corresponding to any arbitrary vertical distribution of atmospheric radon daughters can be calculated easily.