Expansion of the nuclear charge radius increases with the number of neutrons added to the nucleus
Joint press release of the GSI Helmholtzzentrum für Schwerionenforschung, the Helmholtz Institute Mainz, and Johannes Gutenberg University Mainz
Where does the periodic table of chemical elements end and which processes lead to the existence of heavy elements? An international research team reports on experiments performed at the GSI/FAIR accelerator facility and at Johannes Gutenberg University Mainz (JGU) to come closer to an answer to this question. They gained insight into the structure of atomic nuclei of fermium (element 100) with different numbers of neutrons. Using forefront laser spectroscopy techniques, they traced the evolution of the nuclear charge radius and found a steady increase as neutrons were added to the nuclei. This indicates that localized nuclear shell effects have a reduced influence on the nuclear charge radius in these heavy nuclei. The results were published in Nature.
Our group contributed by making the samples available for sudying the two most neutron-rich fermium isotopes: fermium-257 was produced at the HFIR reactor at ORNL and used directly thanks to its long half-life of 100 days; fermium-255 was obtained from a sample of 275-day einsteinium-254 (element 99) from ORNL, which was neutron-irradiated in the high-flux reactor at ILL Grenoble to breed 49-d einsteinium-255. This beta-decays into 20-h fermium-255, which was milked off the einsteinium-255 mother in regular intervals every several days, by using a chemical separation procedure optimized to separate the two chemically very similar actinide elements einsteinium and fermium. In this way, samples suitable for the laser spectroscopy studies carried out by the groups of Professors Michael Block and Klaus Wendt were produced.
More Info:
- Press release at GSI, Darmstadt (german/english)
- Press release at the Johannes Gutenberg University Mainz (JGU) (german/english)
- Publication in Nature:
Warbinek, J., Rickert, E., Raeder, S., Albrecht-Schönzart, T., Andelic, B., Auler, J., Bally, B., Bender,
M., Berndt, S., Block, M., Brizard, A., Chauveau, P., Cheal, B., Chhetri, P., Claessens, A., de Roubin,
A., Devlin, C., Dorrer, H., Düllmann, C.E., Ezold, J., Ferrer, R., Gadelshin, V., Gaiser, A., Giacoppo,
F., Goriely, S., Gutiérrez, M.J., Harvey, A., Hasse, R., Heinke, R., Heßberger, F.-P., Hilaire, S., Kaja,
M., Kaleja, O., Kieck, T., Kim, E., Kneip, N., Köster, U., Kraemer, S., Laatiaoui, M., Lantis, J.,
Lecesne, N., Loria Basto, A.T., Mistry, A.K., Mokry, C., Moore, I., Murböck, T., Münzberg, D.,
Nazarewicz, W., Niemeyer, T., Nothhelfer, S., Péru, S., Raggio, A., Reinhard, P.-G., Renisch, D.,
Rey-Herme, E., Romans, J., Romero Romero, E., Runke, J., Ryssens, W., Savajols, H., Schneider,
F., Sperling, J., Stemmler, M., Studer, D., Thörle-Pospiech, P., Trautmann, N., Urquiza-González, M.,
van Beek, K., Van Cleve, S., Van Duppen, P., Vandebrouck, M., Verstraelen, E., Walther, T., Weber,
F., Wendt, K.
Smooth trends in fermium charge radii and the impact of shell effects
Nature 634, 1075–1079 (2024)
DOI: https://doi.org/10.1038/s41586-024-08062-z