Stochastic method for calculating the influence of track structure on the yield of free radicals in aqueous solutions

The beads on a string model proposed by Ganguly and Magee [A.K. Ganguly and J.L. Magee, J. Chem. Phys. 25, 129(1956)] was generalized to allow Monte Carlo techniques to be used in calculating the influence of track structure on the yield of free radicals at early times following energy deposition by ionizing radiation in aqueous solutions. The results of the Monte Carlo calculations can be interpreted in terms of an effective linear energy transfer (LET) that is significantly less than the stopping power of the radiation when the track structure has a diffuse radial distribution due to energy transport by delta-rays. By incorporating this effective LET for deuterons and alpha particles into a one radical approximation, the model can account for the effect of track structure on the yield of hydrated electrons measured by Sauer and co-workers [M.C. Sauer, Jr., K.H. Schmidt, E.J. Hart, C.A. Naleway and C.D. Jonah, Radiat. Res. 70, 91(1977)]. 3 figures