https://doi.org/10.1140/epja/s10050-025-01778-0
Regular Article - Experimental Physics
Lifetimes and electromagnetic transition strengths in 
Er
1
Faculty of Physics, St. Kliment Ohridski University of Sofia, 1164, Sofia, Bulgaria
2
Institut für Kernphysik, Universität zu Köln, 50937, Köln, Germany
3
Institut für Kernphysik, Technische Universität Darmstadt, 64289, Darmstadt, Germany
4
School of Computing, Engineering, and Physical Sciences, University of the West of Scotland, PA1 2BE, Paisley, UK
5
SUPA, Scottish Universities Physics Alliance, Glasgow, UK
6
Université Paris-Saclay, CNRS/IN2P3, IJCLab, 91405, Orsay, France
a
This email address is being protected from spambots. You need JavaScript enabled to view it.
Received:
22
August
2025
Accepted:
20
December
2025
Published online:
25
January
2026
We report on new lifetime measurements of the yrast states (6
to 12) of Er, performed using the Recoil Distance Doppler-Shift (RDDS) method at the Cologne FN Tandem accelerator. From the extracted lifetimes, B(E2) values were determined to trace the evolution of nuclear collectivity at high spin. At low-to-moderate spins (
), the trend of the B(E2) values is described qualitatively by the Confined Beta-Soft (CBS) model, confirming the nucleus’s position in the transitional region between X(5) symmetry and the SU(3) rigid rotor limit. At higher spins (
), a sharp drop in the B(E2) strengths indicates the beginning of backbending, marking a clear breakdown of the purely collective description.
Copyright comment Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
© The Author(s), under exclusive licence to Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature 2026
Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
