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Stopping power for ion channeling through carbon nanotubes

Abstract:

We investigate the energy losses of MeV protons moving paraxially in single-wall carbon nanotubes (CNTs) due to excitations of carbon valence electrons. To elucidate the significance of the large variation in electron density inside the nanotubes, we compare the energy losses based on a two-dimensional (2-D) hydrodynamic model of the nanotube wall with those based on a three-dimensional dielectric function for a non-homogeneous electron gas, which includes both local and non-local contributions to proton stopping power. While the latter contribution agrees closely with the stopping power from the 2-D model at high proton speeds and in central regions of the nanotube, the local contribution yields a significant increase in stopping power when the proton moves close to the nanotube wall. These results will be useful in future simulations of projectile trajectories and in assessing the electronic damage to CNTs in the course of ion channeling at medium and high energies.