Speaker
Description
High-resolution laser spectroscopy is a powerful tool to extract nuclear structure data in a nuclear-model-independent manner. The isotope shift gives direct access to changes in mean-square charge radii, while the extracted hyperfine parameters give access to the nuclear spin, magnetic dipole and electric quadrupole moment. All this provides information on e.g. deformation, shape coexistence and shell structure. Recently, measurements of ground state properties have also proven exceptionally potent in testing state-of-the-art nuclear theory.
The Pd isotopes are located in a transitional area between chains which display smooth trends in the charge radii (Sn region), and a region where the charge radii and electric quadrupole moments show evidence of a shape change at N=60, centred around yttrium. Between both however, i.e. Tc, Ru, Rh and Pd, no optical spectroscopic information has been available for radioactive nuclei so far. This is partly due to the refractory character of these elements, making production challenging for many facilities, but also their complex atomic structure.
At the IGISOL facility, these difficulties were overcome thanks to the chemically insensitive production method, and the installation of a charge-exchange cell. Collinear laser spectroscopy was performed on unstable Pd isotopes, known to be deformed from decay spectroscopy studies, although there is disagreement on the (possible) change in deformation. The measured nuclear charge radii, spins and electromagnetic moments [1,2] will be presented in this contribution, and the implication on the deformation will be discussed. Additionally, the results will be compared to Density Functional Theory (DFT) calculations using Fayans functionals. As most recent benchmarks of nuclear DFT were performed on spherical systems, close to (doubly-)magic systems, this presents a stringent test of the Fayans functionals for well-deformed isotopes.
[1] S. Geldhof et al., Phys. Rev. Lett. 128, 152501 (2022).
[2] A. Ortiz-Cortes, PhD thesis, University of Jyväskylä and Normandy University (2023).
