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