Calculation of the Ionization due to Radioactive Substances in the Ground

In earlier calculations it seems not to have been considered that the penetrating radiation from the ground can, independent of the density and composition of the ground, be expressed by the simple formula I = C × S, where S is the proportion of radioactive element in g/g and C is a constant. Formulas for the ionization in the case when the ground is covered with an absorber of greater density than air, or when the radiation travels through air for long distances, are derived. The ionization from various minerals is calculated and is found to agree in magnitude with measured values. Curves, showing the decrease in the ionization as a function of the depth of snow cover, are given for three different values of snow density. The decrease in the dose rate with the altitude above the earth's surface is shown graphically.