On the stochastic treatment of fast chemical reactions.

A Monte Carlo code was developed to stimulate stochastically the fast reactions of radiolysis products in water. The results of these calculations show that treatments based on deterministic kinetic rate equations do not reproduce correctly the evolution in time of the number of species. Ad hoc initial distributions of species in spurs, of the type used in deterministic approaches, are compared with more realistic distributions obtained from Monte Carlo-generated particle tracks. The effects of using either type of distribution, stochastically or deterministically, are discussed.