The gamma-ray response of pararosaniline cyanide dosimeter solutions

Abstract

Triphenylmethane dye derivatives, especially the colorless nitriles in organic or aqueous solution, serve as convenient radiation dosimeters. With large absorbed doses (10 3−10 6 rads), permanent ionized dye is produced with sufficient color for routine photometric measurement. If a polar solvent is used and the solution is oxygenated and stabilized by weak acid, the optical density measured at the absorption maximum of dye is a linear function of dose. Dye yield varies with the type of solvent, concentration of the dye precursor, temperature during irradiation, acid and oxygen content and batch of dye precursor used. Additions of small amounts of acid to solutions prevent back reactions. Dissolved oxygen or a wek oxidizing agent helps extend the dose range of response by scavenging free-radical agents formed in the solvent during irradiation. Suitable plastic containers may be used, without the need for ultraclean handling procedures or superdistilled solvents. Since the main sources of systematic error are easily controlled and since the new dosimeter solutions may be used over a wide dose range, they show advantages over other chemical dosimeters for many applications.