Hannover 2016 – wissenschaftliches Programm
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A: Fachverband Atomphysik
A 27: Precision spectroscopy of atoms and ions I (with Q)
A 27.2: Vortrag
Mittwoch, 2. März 2016, 15:00–15:15, f428
MCDF Isotope-Shift Calculations for Medium and Heavy Elements — •Randolf Beerwerth1,2 and Stephan Fritzsche1,2 — 1Helmholtz-Institut Jena, 07743 Jena, Germany — 2Theoretisch-Physikalisches Institut, Universit{\"a}t Jena, 07743 Jena, Germany
The isotope shift is described in terms of the mass and field-shift parameters. The former arises due to the nuclear recoil, while the latter links the electronic response to changes in the nuclear radius. This allows to use optical spectroscopy to obtain information about the nucleus, when the isotope-shift parameters are known. When it is infeasible to determine the isotope-shift parameters purely experimentally, atomic calculations can instead be utilized to provide estimates.
We apply the Multi-Configuration Dirac-Fock (MCDF) method to calculate the isotope-shift parameters for medium to heavy elements. After computation of the wave function, we utilize the configuration-interaction method to calculate the isotope-shift parameters for a chain of isotopes.
Since the isotope shift of heavy elements is dominated by the field shift, we put special emphasis on its computation. Very often it is estimated from the electronic charge density inside the nucleus, however this estimate is only precise for light elements. For light to medium elements, our method agrees very well with this estimate. However, for heavy elements we obtain significantly lower values.
We present results for Actinium and Nobelium, where several experiments were recently performed. The extracted nuclear parameters compare well with results for other elements.