Time- and space-resolved Monte Carlo study of water radiolysis for photon, electron and ion irradiation.

Time-dependent yields of the most important products of water radiolysis E(aq)(-), (*)OH, H(*), H(3)O(+), H(2), OH(-) and H(2)O(2) have been calculated for (60)Co-photons, electrons, protons, helium- and carbon-ions incident onto water. G values have been evaluated for the interval from 1 ps to 1 mus after initial energy deposition as a function of time, as well as after 1 ns and at the end of the chemical stage as a function of linear energy transfer (LET), covering an interval from approximately 0.2 up to 750 keV/microm by means of different particle types. In this work, the modules of the biophysical Monte Carlo track structure code PARTRAC dealing with the simulation of prechemical and chemical stages have been improved to extend interaction data sets for heavier ions. Among other newly selected parameter values, the thermalisation distance between the point of generation and hydration of subexcitation electrons has been adopted from recent data in the literature. As far as data from the literature are available, good agreement has been found with the calculated time- and LET-dependent yields in this work, supporting the selection of the revised parameter values.