Intra-atomic Double Scattering of Binary Encounter Electrons in Collisions of Fast Heavy Ions with Atoms and Molecules

Abstract

We present first experimental evidence for intra-atomic double scattering of binary encounter electrons produced in collisions of 5.9 MeV/u ${\mathrm{U}}^{29+}$ with neon, xenon, and molecular gases. A broad distribution of electrons is observed at a velocity twice the velocity of the moving ion ( ${v}_{P}$) at angles ${\ensuremath{\vartheta}}_{e}$ up to 135\ifmmode^\circ\else\textdegree\fi{}. We attribute this emission pattern to well-known target binary encounter electrons around ${2v}_{P}$ at extreme forward laboratory angles that are subsequently elastically scattered in the target nuclear potential to the large angles observed.