Freiburg 2024 – wissenschaftliches Programm

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MS: Fachverband Massenspektrometrie

MS 5: Heavy and Superheavy Nuclei

MS 5.1: Hauptvortrag

Mittwoch, 13. März 2024, 11:00–11:30, HS 3042

Laser spectroscopy studies of heavy actinides — •Dominik Studer for the Fermium collaboration — Helmholtz-Institut Mainz — GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt

Precise measurements of nuclear ground-state properties, e.g., spins, electromagnetic moments, and charge radii provide data on the shell structure and serve as benchmarks for theory, which contribute to obtaining a comprehensive picture of nuclear phenomena in heavy nuclei. However, experiments with exotic artificial transuranics are challenging due to limited sample sizes or production yields, and scarcity of atomic structure information. Here we report on an extended laser spectroscopy campaign, targeting isotopes of Cf, Es and Fm. These nuclides were predominantly produced at ORNL’s High Flux Isotope Reactor. Part of the sample from ORNL was subsequently also re-irradiated at the high-flux reactor at ILL Grenoble, France, to produce ²⁵⁵Es, serving as a ²⁵⁵Fm generator, as well as ^253,254Cf. Laser spectroscopic studies were carried out at the RISIKO mass separator at the University of Mainz using resonance ionization spectroscopy. Broadband laser scans served to explore atomic spectra, and high-resolution spectroscopy - feasible with sample sizes on the femtogram level - allowed the extraction of isotope shifts and nuclear moments from hyperfine spectra. On-line laser spectroscopy of shortlived Fm isotopes, produced by nuclear fusion reactions at the GSI accelerator facility in Darmstadt, complement these studies and allowed the exploration of the N=152 neutron shell gap.

Keywords: Actinides; Laser spectroscopy