Monte Carlo determination of gamma-ray dose rate with the GEANT system

Conversion factors for the dose rate 1 m above the ground level from the measured activities for different gamma-ray emitters in soil are calculated using the Monte Carlo method. The calculations are based on the GEANT system developed at CERN, Geneva. Results for the uniform and surface distribution of the emitters in the soil are given for gamma-ray energies in the interval between 20 keV and 3 MeV. They are similar to those of the recent report of ICRU that indicates that GEANT system is suitable for application in health physics problems. For 137Cs the dose rates for plane sources at different depths are given, which allow for the calculation of the dose rate for any depth distribution of the activity in the soil.