Ultralow-Energy Electrons from Fast Heavy-Ion Helium Collisions: The “Target Cusp“

W. Schmitt
R. Moshammer
F. S.C. O'Rourke
H. Kollmus
L. Sarkadi
R. Mann
S. Hagmann
Ronald E. Olson, Missouri University of Science and Technology
J. Ullrich

Abstract

Doubly differential cross sections d2σ/dν‖dν⊥ have been obtained by mapping the 3-dimensional velocity space of ultralow- and low-energy electrons \(1.5 meV<=Ee<=100 eV\) emitted in singly ionizing 3.6 MeV/u Au53+ on helium collisions. A sharp \(ΔEFWHMe⊥<=22 meV\) asymmetric peak centered at = 0 is observed to emerge at ultralow energies from the strongly forward shifted low-energy electron velocity distribution. The shape of this "target cusp," which is very sensitive on the details of the two-center potential, is in excellent accord with theoretical predictions. © 1998 The American Physical Society.