corner
corner

Phys. Rev. Lett. 101, 093201 (2008) [4 pages]

Coulomb Four-Body Problem: Electron-Impact Double Ionization of Helium in the Threshold Regime

Download: PDF (256 kB) Buy this article Export: BibTeX or EndNote (RIS)

Xueguang Ren, Alexander Dorn, and Joachim Ullrich
Max-Planck-Institute for Nuclear Physics, 69117 Heidelberg, Germany

Received 8 May 2008; published 29 August 2008

See accompanying Physics Synopsis

Double ionization of helium by electron impact is studied in a kinematical complete experiment in the threshold regime at 5 eV excess energy. As expected the recoil ion carries the full initial projectile momentum and the emitted electrons’ sum momentum in average is zero. The electron emission is revealed to be completely dominated by the symmetric 120° configuration predicted by many threshold theories but never observed experimentally before. Fully differential cross sections show a more complex structure than expected for a pure threshold collision dynamics.

© 2008 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevLett.101.093201
DOI:
10.1103/PhysRevLett.101.093201
PACS:
34.80.Dp