Speaker
Description
The heaviest elements are of interest to nuclear and atomic physicists due to their peculiar properties. While nuclear shell structure effects are responsible for their very existence stabilizing them against spontaneous disintegration, the structure of their electronic shells is affected by strong relativistic effects leading to different atomic and chemical properties compared to their lighter homologs. The atomic structure can be probed by laser spectroscopy. This is a powerful tool to unveil fundamental atomic and, by detecting subtle changes in atomic transitions, nuclear properties. The scarcity in atomic information on the heavy element of interest, the limited availability, and the rather short half-lives make experimental investigations challenging and demand very sensitive experimental techniques.
Here, laser spectroscopic studies of accelerator produced heavy nuclei were performed using the RADRIS (RAdiation Detected Resonance Ionization Spectroscopy) setup for laser spectroscopy inside a buffer gas cell. This sensitive technique enabled laser spectroscopy measurements on isotopes of nobelium (No, $Z=102$), fermium (Fm, $Z=100$) and californium (Cf, $Z=98$), which were produced with atom-at-a-time quantities in fusion-evaporation reactions at the velocity filter SHIP at GSI, Darmstadt.
Complementary hot-cavity laser spectroscopy on radio-chemically purified samples allowed for off-line investigation of long-lived, reactor-bred isotopes of the heavy actinides curium (Cm, $Z=96$), californium, einsteinium (Es, $Z=99$), and fermium. This experimental work is accompanied by improvements of theoretical atomic calculations enabling the determination of nuclear ground state properties from the extracted atomic observables of isotope shifts and hyperfine structure parameters. This provides insight to the peculiar nuclear nature and, in particular, the deformation of the heaviest elements. The obtained results will be discussed in view of nuclear theory predictions together with perspectives for laser spectroscopic investigations in even heavier elements.