Oxidation of Ferrous Sulfate by High-Energy Electrons and the Influence of the Polarization Effect

Aqueous solutions of ferrous ammonium sulfate in 0.8 N sulfuric acid have been irradiated with high-energy electrons and the resultant oxidation of the ferrous ion measured. This reaction can be used as a dosimeter to measure the energy absorbed by a given volume of water from the incident electrons. The ratio of the energy loss by electrons in water and in a gas such as air is not constant but is a function of the electron velocity. This variation of relative energy loss in gaseous and condensed media as a function of electron velocity is a consequence of the polarization effect which is discussed below. The ionization produced in an air cavity has been measured under identical conditions as used in the electron irradiation of the aqueous solutions of ferrous sulfate. These measurements support both the existence of the polarization effect and the calculation of its magnitude. The technique of the application of ferrous sulfate oxidation, originally described by Fricke and Morse (1), to dosimetry problems has been described extensively in the literature (2) and will not be reviewed in detail here. The source of electrons was a 22.5-Mev betatron from which the electron beam