title: Probing scattering wave functions close to the nucleus.
abstract: Recently, three-dimensional imaging of the ejected electrons following 100 MeV/amu C6+ single ionization of helium led to the observation of a new structure not predicted by theory [Nature (London) 422, 48 (2003)]]. Instead of the usual "recoil lobe" centered on the momentum-transfer axis, a ring-shaped structure centered on the beam axis was observed. New measurements at 2 MeV/amu exhibit a similar structure, which is now predicted by theory. We argue that the same theory failed at 100 MeV/amu because the faster projectiles probe distances much closer to the nucleus, where our multiple-scattering model is expected to break down.
authors.affiliation: Laboratory for Atomic, Molecular and Optical Research, Physics Department, University of Missouri-Rolla, Rolla, Missouri 65409-0640, USA.
authors.forename: D H
authors.initials: DH
authors.lastname: Madison
authors.forename: D
authors.initials: D
authors.lastname: Fischer
authors.forename: M
authors.initials: M
authors.lastname: Foster
authors.forename: M
authors.initials: M
authors.lastname: Schulz
authors.forename: R
authors.initials: R
authors.lastname: Moshammer
authors.forename: S
authors.initials: S
authors.lastname: Jones
authors.forename: J
authors.initials: J
authors.lastname: Ullrich