title: Screened radiative corrections from hyperfine-split dielectronic resonances in lithiumlike scandium.
abstract: Term energies for dielectronic-recombination Rydberg resonances below 0.07 eV are determined for Sc18+ with absolute accuracies below 0.0002 eV by electron collision spectroscopy in an ion storage ring, using the twin-electron-beam technique and a cryogenic photocathode. The lithiumlike 2s_{1/2}-2p_{3/2} transition energy for Z=21 is determined to 4.6 ppm, less than 1% of the few-body effects on radiative corrections. Features from the hyperfine structure of the 2s state could be resolved in the dielectronic-recombination spectrum.
authors.affiliation: Max-Planck-Institut für Kernphysik, Heidelberg, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Lestinsky
authors.forename: E
authors.initials: E
authors.lastname: Lindroth
authors.forename: D A
authors.initials: DA
authors.lastname: Orlov
authors.forename: E W
authors.initials: EW
authors.lastname: Schmidt
authors.forename: S
authors.initials: S
authors.lastname: Schippers
authors.forename: S
authors.initials: S
authors.lastname: Böhm
authors.forename: C
authors.initials: C
authors.lastname: Brandau
authors.forename: F
authors.initials: F
authors.lastname: Sprenger
authors.forename: A S
authors.initials: AS
authors.lastname: Terekhov
authors.forename: A
authors.initials: A
authors.lastname: Müller
authors.forename: A
authors.initials: A
authors.lastname: Wolf