13-17 June 2022
Berkeley, CA
US/Pacific timezone

Laser Spectroscopy of the Heaviest Actinides

13 Jun 2022, 12:10
Berkeley, CA

Berkeley, CA

Lawrence Berkeley National Laboratory
Oral Oral Presentations NS2022 Plenary


Jeremy Lantis (Johannes Gutenberg University Mainz)


The interaction between electrons and the atomic nucleus introduces an avenue for laser spectroscopy measurements to probe changes in the nuclear structure across an isotopic chain, providing a nuclear model-independent method to determine fundamental properties such as the spin, the mean-squared charge radius, and nuclear moments. Laser spectroscopic techniques have been historically successful for wide swaths of the chart of the nuclides, but only recently has the heavy actinide region become accessible through the RAdioactive decay Detected Resonance Ionization Spectroscopy (RADRIS) technique [1,2] used at the Separator for Heavy Ion Products (SHIP) at GSI, Darmstadt, Germany. Experimental access to actinides has opened a window to unusual features in the nuclear structure. Stretching from the $N$ = 126 to the $N = 152$ shell closures, the actinides feature both oblate and prolate nuclei, the presence of $K$-isomers, and rotational bands that are all hallmarks of deformation. Additionally, the large Coulomb repulsion in the heavier actinides results in a central depression in the nuclear density and has been theorized to potentially result in bubble nuclei [3]. The RADRIS technique was used to identify the first atomic transition [4] as well as to determine the nuclear charge radii and nuclear moments of $^{252-254}$No [5]. New technological developments have extended the range of lifetimes accessible by the RADRIS technique and permitted measurement of $^{248,249,250,254}$Fm, crossing the shell closure at $N$ = 152, with additional measurements of $^{255,257}$Fm performed offline with reactor bred samples from Oak Ridge National Laboratory, Oak Ridge, USA, and extended the isotopic chain of nobelium to $^{255}$No. The results of these measurements, which have posed a challenge for existing theoretical models, will be discussed. The development of a new laser spectroscopic technique for use at GSI will be discussed, where nuclear reaction products are measured in a hypersonic gas jet [6,7], retaining the high sensitivity of the RADRIS technique but improving the achievable spectral resolution by an order of magnitude in addition to providing access to short-lived species such as the 275 ms $K$ = 8$^-$ isomer in $^{254}$No.

[1] H. Backe et al., Eur. Phys. J. D 45 (2007) 99-106
[2] F. Lautenschläger et al., Nucl. Instrum. Meth. B 383 (2016) 115-122
[3] J. Dechargé et al., Nucl. Phys. A 716 (2003) 55-86
[4] M. Laatiaoui et al., Nature 538 (2016) 495-498
[5] S. Raeder et al., Phys. Rev. Lett 120 (2018) 232503
[6] R. Ferrer et al., Nat. Commun. 8 (2017) 14520
[7] S. Raeder et al., Nucl. Instrum. Methods. Phys. Res. B 463 (2020) 272-276

Primary authors

Jeremy Lantis (Johannes Gutenberg University Mainz) Prof. Thomas Albrecht-Schönzart (Florida State University) Mr Julian Auler (Johannes Gutenberg University Mainz) Dr Benjamin Bally (CEA ENST) Dr Michael Bender (Institut de Physique des deux Infinis de Lyon) Prof. Michael Block (GSI / Helmholtz Institute Mainz / Johannes Gutenberg University Mainz) Dr Pierre Chauveau (GANIL) Prof. Bradley Cheal (University of Liverpool) Dr Premaditya Chhetri (KU Leuven) Mr Arno Claessens (KU Leuven) Dr Charlie Devlin (University of Liverpool) Mr Holger Dorrer (Johannes Gutenberg University Mainz) Prof. Christoph Düllmann (GSI / Helmholtz Institute Mainz / Johannes Gutenberg University Mainz) Ms Julie Ezold (Oak Ridge National Laboratory) Dr Rafael Ferrer (KU Leuven) Mr Vadim Gadelshin (Johannes Gutenberg University Mainz) Dr Alyssa Gaiser (Florida State University) Dr Francesca Giacoppo (GSI) Dr Stephane Goriely (Université Libre de Bruxelles) Ms Ashley Harvey (Oak Ridge National Laboratory) Dr Reinhard Heinke (Johannes Gutenberg University Mainz) Dr Heßberger Fritz-Peter (GSI) Dr Stephane Hilaire (CEA DAM) Ms Magdalena Kaja (Johannes Gutenberg University Mainz) Dr Oliver Kaleja (GSI) Dr Tom Kieck (GSI) Mr EunKang Kim (Johannes Gutenberg University Mainz) Ms Nina Kniep (Johannes Gutenberg University Mainz) Prof. Ulli Köster (Institut Laue-Langevin) Dr Sandro Kraemer (KU Leuven) Dr Peter Kunz (TRIUMF) Dr Mustapha Laatiaoui (Johannes Gutenberg University Mainz) Dr Werner Lauth (Johannes Gutenberg University Mainz) Dr Nathalie Lecesne (GANIL) Dr Vladimir Manea (GANIL / ICJ Lab Orsay) Dr Andrew Mistry (GSI) Dr Christoph Mokry (Johannes Gutenberg University) Mr Danny Münzberg (GSI / Johannes Gutenberg University Mainz / Helmholtz Institute Mainz) Dr Mürbock Tobias (TRIUMF) Mr Steven Nothhelfer (GSI / Helmholtz Institute Mainz / Johannes Gutenberg University Mainz) Dr Sophie Peru-Desenfants (CEA DAM) Dr Sebastian Raeder (GSI / Helmholtz Institute Mainz) Mr Emmanuel Rey-Herme (CEA) Ms Elisabeth Rickert (GSI / Helmholtz Institute Mainz / Johannes Gutenberg University Mainz) Mr Jekabs Romans (KU Leuven) Dr Elisa Romero Romero (Johannes Gutenberg University Mainz) Dr Jörg Runke (Johannes Gutenberg University Mainz) Prof. Hervé Savajols (GANIL) Dr Fabian Schneider (Helmholtz Institute Mainz) Dr Simon Sels (KU Leuven) Dr Joseph Sperlin (Florida State University) Mr Matou Stemmler (Johannes Gutenberg University Mainz) Dr Dominik Studer (Johannes Gutenberg University Mainz) Dr Barbara Sulignano (CEA) Ms Petra Thörle-Pospiech (Johannes Gutenberg University Mainz) Prof. Norbert Trautmann (Johannes Gutenberg University Mainz) Ms Shelley Van Cleve (Oak Ridge National Laboratory) Prof. Piet Van Duppen (KU Leuven) Dr Marine Vandebrouck (CEA) Dr Elise Verstraelen (KU Leuven) Prof. Thomas Walther (TU Darmstadt) Ms Jessica Warbinek (GSI / Johannes Gutenberg University Mainz) Mr Felix Weber (Johannes Gutenberg University Mainz) Prof. Klaus Wendt (Johannes Gutenberg University Mainz) Dr Alexander Yakushev (GSI)

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