Binary electron production by 1 MeV/u Au ions

The absolute cross section for the production of binary encounter electrons has been measured at zero degrees for 1 MeV/u Auq+ (q=12-37) colliding with helium. It has been experimentally found that as the charge state of the incident ion is increased (1) the binary peak magnitude increases, (2) the electron energy at which the peak occurs decreases, and (3) the peak broadens. The absolute cross sections are compared with theoretical results. Classical Trajectory Monte Carlo calculations are found to give good account for the magnitude and the shift to lower election energy of the peak. The Continuum Distorted Wave-Eikonal Initial State approximation is shown to yield cross sections which are much smaller in magnitude than the experiments, but reproduce well the relative magnitudes and shapes of the peaks for these ions. It is noted that the increase in the binary peak magnitude with increasing ionic charge state is in distinction to previous measurements which showed enhancement of the binary peak with decreasing charge state for clothed ions