Calculation of conversion factors dose for natural radionuclides gamma-emitting soil

The determination of dose conversion deposited in the air because of the emitters of radioactivity gamma distributed in the ground is very significant in the field of radioprotection and in sciences relating to the studies of the ground. It rests on the knowledge of the dose conversion factors (FCDs) relating to the emitters of gamma radiation distributed in the ground. The calculation of the flow of these photons can be done with various methods, analytical, semi - analytical or numerical. We tried in this work to remake the calculation of these factors to improve their precision by optimizing the geometry of the problem and by introducing another factor into our calculation which is the Sky shine effect using the Monte Carlo method by using code of the CERN. These results will consequently be applied to the radionuclide present in the ground to determine their dose deposited in the air. (Author). 10 refs