Results on electron irradiated Fricke solutions at low temperatures

This work presents results concerning the possibility of extending Fricke d osimetry at -196 degrees C and -5 degrees C irradiation temperatures. Froze n samples of Fricke solution at -196 degrees C and, respectively -5 degrees C, and samples of Fricke solution at room temperature were simultaneously irradiated with the 5 MeV electron beam of a linear accelerator. Our result s showed for the frozen irradiated Fricke solutions apparent dose values wi th approximately one order of magnitude smaller than the real values, as ob tained with liquid Fricke solution, in the case of -196 degrees C irradiati on temperature, and dose values approximately reduced by a factor of two, i n the case of -5 degrees 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+. Th e apparent dose Values obtained for the -5 degrees C and -196 degrees C fro zen Fricke solutions showed a linear dependence with the real dose values, indicating that the data obtained might be used to create a calibrating cur ve. More data will be collected in order to test the accuracy and the repro ducibility of the system. (C) 2000 Elsevier Science B.V. All rights reserve d.