Giant Barkas effect observed for light ions channeling in Si

Abstract

Measurements of the electronic energy loss are presented for ⁴He and ⁷Li ions channeling along the Si main axial directions at intermediate to high projectile energies. The Barkas effect, an energy-loss enhancement proportional to the third power of the projectile charge at high energies, is clearly separated from other processes. It reaches about 50% for Li ions channeling along the Si <110> direction. The observed Barkas contribution from the valence-electron gas is in fair agreement with the Lindhard model.