We analyze the dependence on the exit angle of the energy loss suffered by the fragment protons resulting from the dissociation of swift ${\mathrm{H}}_2^{+}$ molecules after traversing thin carbon foils. The trajectory of each proton was followed by numerically solving the corresponding equations of motion, using the dielectric formalism to describe the forces due to electronic excitations in the medium, whereas the repulsion between protons from the same molecule was taken into account by using a Coulomb potential. Nuclear collisions with target nuclei were incorporated through a Monte Carlo code. The contribution of each one of the above interactions to the joint angle and energy-loss spectra of the fragment protons is discussed as a function of the molecule incident energy and foil thickness.

• Received 14 July 1999

DOI:https://doi.org/10.1103/PhysRevA.62.012901