Stochastic models of short-time kinetics in irradiated liquids

Stochastic models of the short-time kinetics in irradiated liquids are reviewed. Three different approaches are discussed: the first involves a full time-dependent Monte Carlo simulation of the diffusion-reaction processes, at the level of the diffusion approximation, which is computationally expensive; the second is a much faster approach, based on first passage time models and exemplified by the accurate and very efficient Independent Reaction Times model. The final type of model involves the formulation of a master equation, which describes the evolution of discrete spurs. This approach has not been widely used, but a novel general derivation is presented, which may promote its future application. Finally, comments are made on some of the outstanding difficulties and possible area of future development are outlined.