Simulation of the interaction of high-energy C60 cluster ions with amorphous targets

Detailed simulations of the interaction of energetic C60 beams with amorphous targets are presented here. The spatial evolution of the cluster components is calculated accounting for multiple scattering and Coulomb explosion by means of Monte Carlo and molecular dynamics, respectively. The charge states of the individual cluster components ~atoms, atomic ions, fragment cluster ions! as a function of penetration depth are also calculated in tandem with the above calculations by means of the Monte Carlo method. The relative importance of scattering versus Coulomb repulsion is studied as a function of the C60 cluster energy. The effect of the neighboring cluster constituents on the average charge state of the cluster atoms is calculated as a function of the depth of penetration for a C60 cluster of 40 MeV. The calculation accounts for the increase in ionization energy of the atom due to the other constituents. Relative track radii are calculated as a function of penetration depth and good agreement with the experimental results is obtained for the interaction of a 30 MeV carbon cluster with silicon. Track splitting observed well into the target as measured by Dunlop et al. in yttrium iron garnet is obtained in the simulations described here for the case of amorphous carbon, provided the Coulomb repulsion is screened by the four valence electrons. Collective energy deposition enhancement is calculated for the 720 MeV cluster. Here the cluster constituents are nearly fully ionized, thereby minimizing the ambiguity related to the value of the ionic charge in the calculation.