The effects of oxygen and ceric ion concentrations and irradiation temperature on <tex-math>$G({\rm Ce}^{3+})$</tex-math> have been determined at various cerous ion concentrations in dosimeter solutions for the 0.01 to 5.0 megarad range. Potentiometric and spectrophotometric methods of analysis were used in studying the effect of initial ceric ion concentration on <tex-math>$G({\rm Ce}^{3+})$</tex-math>. Particular care was taken in determining <tex-math>$G({\rm Ce}^{3+})$</tex-math> values for the various solute parameters used in the above dose range to eliminate the need to calibrate solutions against the Fricke dosimeter. A simple equation gives <tex-math>$G({\rm Ce}^{3+})$</tex-math> with high precision for any initial ceric or cerous ion concentration used in the above dose range and any normal irradiation temperature. Deoxygenation and oxygenation of solutions respectively decrease and increase the <tex-math>$G({\rm Ce}^{3+})$</tex-math> value obtained from aerated solutions at any particular cerous ion concentration. The oxygen effect is attributed to intraspur scavenging of hydrogen atoms. It is shown that <tex-math>$G({\rm Ce}^{3+})$</tex-math> at zero solute concentration can only be estimated with accuracy if the oxygen effect is taken into account.

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