Approximations to saturation curves in gas-filled parallel-plate ionization chambers.

Saturation curves were measured for air and nitrogen in the exposure rate range from approximately 1 to approximately 500 R/min. Because of the differences between the ion-ion versus electron-ion recombination processes, the air and nitrogen saturation curves differ considerably even when measured under identical chamber and exposure rate conditions. A comparison between our experimental data and various approximations to saturation curves in air, developed by others, is given. It is then shown that the air saturation curve can be approximated by a sum of three simple exponential functions.