Seminarium Fizyki Jądra Atomowego

The investigation of superheavy elements (SHE), i.e., elements with Z > 103, attracts interest from atomic and nuclear physics as well as from chemistry. On the one hand, relativistic effects strongly impact theatomic structure and may alter the chemical properties of these elements compared to their lighter homologues. This manifests, for example, in changes of atomic ground-state configurations and may eventually result in a deviation from the Periodic Table’s structure established by Mendeleev more than 150 years ago. On the other hand, the existence of very heavy and superheavy nuclei is governed by the stabilization due to nuclear shell effects that stabilize them against spontaneous fission. Hence, studies of the evolution of their nuclear structure are of paramount importance. In contrast to nuclei close to stability, where sizeable shell gaps are found for spherical nuclei with magic nucleon numbers, in the heaviest nuclei shell gaps, though smaller ones, also appear for deformed nuclei. This has been established around N = 152 and Z = 100 as well as at N = 162 and Z = 108. In the deformed heavy nuclei also K isomers occur, some which have a longer half-life than the ground state, as has been. Studies of the nuclear structure evolution and the existence of isomers is possible through mass measurements and laser spectroscopy [1, 2]. Mass spectrometry yields binding energies for studies of the shell structure and allows us to identify isomers and to obtain their excitation energy. Laser spectroscopy gives access to changes in mean-square charge radii, the nuclear spin, and electromagnetic moments. Pioneering experiments at the GSI in Darmstadt, Germany utilizing the SHP separator in combination with the SHIPTRAP and the RADRIS setups have recently provided such information for several isotopes of the heavy elements californium to rutherfordium [3-7]. In my presentation I will introduce the basic methods, the employed setups, and review selected recent results.

References
1. M. Block, Nucl. Phys. A 944 (2015) 471.
2. M. Block et al., Prog. Nucl. Phys. 116 (2021) 103834.
3. M. Block, F. Giacoppo, F. Hessberger, S. Raeder, Riv. Nuovo Cim. 45, 279 (2022).
4. M. Laatiaoui et al., Nature. 583 (2016) 495.
5. S. Raeder et al., Phys. Rev. Lett. 120 (2018) 232503.
6. P. Chhetri et al., Phys. Rev. Lett. 120 (2018) 263003.
7. O. Kaleja et al., Phys. Rev. C. 106 (2022) 054325.