(e,3e) on helium at low impact energy: the strongly correlated three-electron continuum.
Double ionization of the helium atom by slow electron impact (E(0)=106 eV) is studied in a kinematically complete experiment. Because of a low excess energy E(exc)=27 eV above the double ionization threshold, a strongly correlated three-electron continuum is realized. This is demonstrated by measuring and calculating the fully differential cross sections for equal energy sharing of the final-state electrons. While the electron emission is dominated by a strong Coulomb repulsion, also signatures of more complex dynamics of the full four-body system are identified.
Max-Planck-Institute for Nuclear Physics, Saupfercheckweg 1, 69117 Heidelberg, Germany.
M
M
Dürr
A
A
Dorn
J
J
Ullrich
S P
SP
Cao
A
A
Czasch
A S
AS
Kheifets
J R
JR
Götz
J S
JS
Briggs