Measurements of cosmic-ray ionization and an empirical formula for the dependece of ionization on altitude and latitude

Using the combination of a RSS-111 high pressure ionization chamber and a FD-71 Nal(Tl) scintillation radiometer, cosmic-ray ionization was measured on sea levels and lakes with different altitude and latitude. As a result of summing up the measurements made during the last three years, an empirical formula is obtained which might be used to estimate the cosmic-ray dose rate in air. The mean value of the measurements of the cosmic-ray ionization on the sea levels was 2.93 ± 0.07 x 10-8 Gyh-1. The measurements data of the cosmic-ray ionization at the sea levels and lakes are given as well. The results have been compared with the similar works done by foreign authors