The spectroscopic quadrupole moment of the 21+ state of 12C: A benchmark of theoretical models

J. Saiz-Lomas, M. Petri*, I. Y. Lee, I. Syndikus, S. Heil, J. M. Allmond, L. P. Gaffney, J. Pakarinen, H. Badran, T. Calverley, D. M. Cox, U. Forsberg, T. Grahn, P. Greenlees, K. Hadyńska-Klȩk, J. Hilton, M. Jenkinson, R. Julin, J. Konki, A. O. MacchiavelliM. Mathy, J. Ojala, P. Papadakis, J. Partanen, P. Rahkila, P. Ruotsalainen, M. Sandzelius, J. Sarén, S. Stolze, J. Uusitalo, R. Wadsworth

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


The spectroscopic quadrupole moment of the first 2+ state of 12C has been measured employing the Coulomb-excitation re-orientation technique. Our result of Qs(21+)=+9.3−3.8+3.5efm2 suggests a larger oblate deformation than previously reported. Combining this with the consistently re-analyzed adopted value, we present the most precise value to date of Qs(21+)=+9.5(18)efm2, which is consistent with a geometrical rotor description. This simple outcome is compared to state-of-the-art shell-model, mean-field, ab initio calculations, cluster-based and geometrical-like theories, which show varying degrees of emergent quadrupole collectivity.

Original languageEnglish
Article number138114
Number of pages6
JournalPhysics Letters B
Early online date8 Aug 2023
Publication statusPublished - 10 Oct 2023

Bibliographical note

© 2023 The Author(s). Published by Elsevier B.V.

Funding Information:
The authors acknowledge C. Bertulani, A. Vitturi, A. Moro, M. Gomez, J. M. Quesada, M. Zielinska, and C. Barton for enlightening discussions, and I. Moore for proposing and supporting the production of the 66 Ga source. This work was supported by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – Projektnummer 279384907 – SFB 1245 , the Royal Society under contract number UF150476 , the UK STFC under grant numbers ST/L005727/1 , ST/P003885/1 , the UK STFC ERF fellowship ST/R004056/1 , and by the Director, Office of Science, Office of Nuclear Physics, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231 (LBNL). This project has received funding from the EU HORIZON2020 programme “Infrastructures”, project number 654002 (ENSAR2). U. Forsberg would like to thank Birgit and Hellmuth Hertz' Foundation for financial support.

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