Calculation of initial and primary yields in the radiolysis of water

Monte Carlo calculations have been used to model the initial physical and chemical changes, together with the subsequent diffusion-controlled reactions (up to 10-6 s) which take place following the irradiation of water by electrons from 100 eV to 1 MeV. Investigations were carried out to determine the sensitivity of the radical yields to the following: vapour and liquid cross sections, the initial spatial distribution of electrons and radicals, vibrational cross sections, ionization potentials and initial electron energy for both complete tracks and also for short track sections. The roles played by the vibrational cross sections and by the relaxation of excited states through ionization were found to be most important in determining the sub-excitation electron "entry" energy spectrum, which in turn determines the electrons thermalization distribution and therefore the primary yields. © 1994.