title: Statistical properties of inter-series mixing in helium: from integrability to chaos.
abstract: The photoionization spectrum of helium shows considerable complexity close to the double-ionization threshold. By analyzing the results from both our recent experiments and ab initio three- and one-dimensional calculations, we show that the statistical properties of the spacings between neighboring energy levels clearly display a transition towards quantum chaos.
authors.affiliation: Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin-Dahlem, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Püttner
authors.forename: B
authors.initials: B
authors.lastname: Grémaud
authors.forename: D
authors.initials: D
authors.lastname: Delande
authors.forename: M
authors.initials: M
authors.lastname: Domke
authors.forename: M
authors.initials: M
authors.lastname: Martins
authors.forename: A S
authors.initials: AS
authors.lastname: Schlachter
authors.forename: G
authors.initials: G
authors.lastname: Kaindl