Abstract.
Reliable and precise lifetimes of excited states in 154 Gd and 156 Dy were measured using the recoil distance Doppler shift (RDDS) technique. Excited states of 154 Gd were populated via Coulomb excitation with a 32 S beam at 110 MeV delivered by the FN tandem accelerator at the University of Cologne. For 156 Dy a coincidence plunger experiment was performed at the Laboratori Nazionali di Legnaro with the GASP spectrometer and the Cologne coincidence plunger apparatus using the reaction 124 Sn(36 S,4n)156 Dy at a beam energy of 155 MeV. Shape changes previously suggested to appear in the ground-state band (gsb) of 156 Dy and in the s-band above the first band crossing were not supported by the transition probabilities determined in this work. The measured transition probabilities of 156 Dy and 154 Gd as well as the corresponding energy spectra are compared with the predictions of the recently proposed X(5) model and in the case of 156 Dy also with an IBA fit.
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Received: 30 October 2002, Published online: 2 March 2004
PACS:
21.10.Tg Lifetimes - 27.70. + q \(150 \leq A \leq 189\) - 21.60.Ev Collective models - 23.20.-g Electromagnetic transitions
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Dewald, A., Möller, O., Tonev, D. et al. Shape changes and test of the critical-point symmetry X(5) in N = 90 nuclei. Eur. Phys. J. A 20, 173–178 (2003). https://doi.org/10.1140/epja/i2002-10347-6
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DOI: https://doi.org/10.1140/epja/i2002-10347-6