Electron emission induced by fast heavy ions in a thin silicon crystal

CASWe report observations of backward and forward electron emission by a thin silicon crystal target traversed by 29 MeV/u Pb56+ incident ions. For each incident ion we have performed measurements of backward and forward electron emission, of the energy loss and of the charge state of the transmitted ion. The crystal target was traversed by incident ions either in random incidence or in axial alignment conditions. In both cases these correlated measurements bring original information on electron emission. In random conditions, using an incident ion species with a charge quite far from equilibrium, we observe correlations between backward and forward electron emission, that we understand when analyzing the associated charge exchange and energy-loss data. In channeling conditions, we added electron emission measurements to simultaneous energy-loss and charge state measurements (that are known to characterize quite precisely the type of trajectory of a projectile transmitted through a thin crystal). This allowed us to observe the reduced electron emission due to hyperchanneled ions, that interact mainly with target valence electrons, and also the enhanced electron emission due to projectiles entering the crystal very close to atomic strings