Frozen Solutions of Fricke Dosimeter

Abstract

Commercial product irradiation using ionizing radiation has provided a method to safely treat products in a variety of ways. Temperature is a very important factor when determining the absorbed dose of the product. However, most irradiation complexes apply dosimetric knowledge and calculations in a temperature range above water-freeze temperature to products that Could be at a much lower temperature. This could lead to systematic errors in the irradiation procedures and to health issues. In this paper, we study the response of the Fricke dosimeter as a function of the irradiation temperature. The temperatures studied were: 77 K (liquid nitrogen), 198 K (dry ice as powder), 263 K, 298 K (room temperature), 306 K and 328 K. The results obtained show that the change in valence of iron (11) as a function of the dose was linear for frozen solutions. There is a change of the slope in the doses-response curve that shows the effect of the irradiation temperature. This suggests that a temperature correction should be considered for low-temperature irradiation. This led to the conclusion that the Fricke dosimeter can be used as a dosimeter for low-temperature, and up to 600 Gy. An attempt has been made to theoretically model the chemical response of the Fricke dosimeter and results agreed with the experimental values fairly well.