Results on electron irradiated Fricke solutions at low temperatures

This work presents results concerning the possibility of extending Fricke dosimetry at -196 deg. C and -5 deg. C irradiation temperatures. Frozen samples of Fricke solution at -196 deg. C and, respectively -5 deg. C, and samples of Fricke solution at room temperature were simultaneously irradiated with the 5 MeV electron beam of a linear accelerator. Our results showed for the frozen irradiated Fricke solutions apparent dose values with approximately one order of magnitude smaller than the real values, as obtained with liquid Fricke solution, in the case of -196 deg. C irradiation temperature, and dose values approximately reduced by a factor of two, in the case of -5 deg. C. The explanation of these results is based upon the low rate of migration and the local recombination of the water radicals induced by radiation, which are involved in the reaction Fe2+→Fe3+. The apparent dose values obtained for the -5 deg. C and -196 deg. C frozen Fricke solutions showed a linear dependence with the real dose values, indicating that the data obtained might be used to create a calibrating curve. More data will be collected in order to test the accuracy and the reproducibility of the system