Interaction of hydrogen H_n⁺ clusters with thin carbon foils

A Monte Carlo computer program was developed to calculate the angular distribution of fragments resulting from the breakup of fast hydrogen clusters H_n⁺ when traversing thin amorphous carbon foils. The three-dimensional relative coordinates of each proton in the cluster are given as input. The code begins with a generation of a random orientation of clusters. Next, the foil is divided into slabs and the effects of Coulomb explosion, multiple scattering, and energy loss on each fragment are calculated for successive slabs. The distributions of separations and relative velocities at the exit surface as well as the angular distributions of fragments are then obtained. Therefore, the cluster-stopping-power ratio is given. The use of the code is illustrated in the case of 30-, 40-, 60-, and 80-keV/p clusters, with n=2,3 to 21 odd, impinging on a 2-μg/cm² carbon foil, where experimental results are available.