The Fricke dosimeter: A 1-hit detector

A new analytic expression for the radial dose distribution, from a Monte Carlo calculation in liquid water, has led to a recalculation of the relative response of the Fricke dosimeter irradiated with heavy ions, as a 1-hit detector using track theory. For particles above 1 MeV/μ agreement with data approximates experimental error. The model parameter a/sub o/ is consistent with the observed approach to saturation with Fe++ concentration at about 1 mM. Together with the fitted value of the parameter E/sub o/ the authors find an energy deposition of about 60 eV per sensitive volume. The 1-hit model implies a decline in yield with increasing dose, as observed. The authors need only 2 parameters and the radial dose distribution, but have no need for track core, reaction rates, diffusion constants, differential equations, and an array of reactions. An appropriate fusion of track theory and diffusion kinetics could be made if the parameters of track theory could be derived from diffusion kinetics for gamma-ray or electron irradiation