A Highly Sensitive Chemical Dosimeter for Ionizing Radiation

Abstract

AN aqueous dosimeter capable of measuring radiation doses of less than 100 rads would be an extremely useful tool in the field of radiobiology. Although doses of a few rads can be accurately measured using the resorcinol-stabilized tetrachlorethylene-dye systems¹, such systems where the radiation-induced reaction proceeds by a chain mechanism exhibit certain undesirable characteristics. An alternative to the radiation-induced chain reaction involves the measurement of extremely small amounts of an irradiation product by means of a sensitive analytical technique. Some idea of the extreme sensitivity required is obtained from the fact that a dose of 100 rads will produce approximately 10⁻⁷ moles of product per litre of solution, assuming a reasonable production-rate of unity for G _prod. (that is to say, 1 molecule of product formed per 100 eV. absorbed). An analytical method capable of accurate measurement at such high dilution is spectrophotofluorometry. The production of salicylic acid (which fluoresces in aqueous solution) in irradiated aqueous solutions of benzoic acid seemed to merit investigation, especially because this reaction had been proposed² as suitable for chemical dosimetry.