A Monte Carlo study of cascade fluctuations

The local fluctuations of atomic collision cascade in metals are studied by using a Monte Carlo computer code, TCIS. A parameter thetasub(v) is used to describe the density of damage energy of an individual cascade, which is induced by an ion of primary energy, E0. The mean value, anti thetasub(v), and the energy density straggling, Δthetasub(v), are evaluated from computer simulation tests. A simple relation, Δthetasub(v)=0.45anti thetasub(v), is found from the eight systems studied, with E0 from 4 to 30 KeV. A method is presented to calculate the probabilities of formation of subcascades or surface subcascade. The maximum value of the probability of the surface spike (thetasub(v)>Esub(b)) appears at about 300 keV for the case of Au+->Au system. (orig.)