Lifetime measurements of excited states in <SUP>169,171,173</SUP>Os: Persistence of anomalous <i>B</i>(<i>E</i>2) ratios in transitional rare earth nuclei in the presence of a decoupled <i>i</i><sub>13/2</sub> valence neutron



Zhang, W, Cederwall, B, Doncel, M, Aktas, O, Ertoprak, A, Liotta, R, Qi, C, Grahn, T, Singh, BS Nara, Cullen, DM
et al (show 32 more authors) (2021) Lifetime measurements of excited states in <SUP>169,171,173</SUP>Os: Persistence of anomalous <i>B</i>(<i>E</i>2) ratios in transitional rare earth nuclei in the presence of a decoupled <i>i</i><sub>13/2</sub> valence neutron. PHYSICS LETTERS B, 820. p. 136527.

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Abstract

Lifetimes of low-lying excited states in the νi13/2+ bands of the neutron-deficient osmium isotopes 169,171,173Os have been measured for the first time using the recoil-distance Doppler shift and recoil-isomer tagging techniques. An unusually low value is observed for the ratio B(E2;21/2+→17/2+)/B(E2;17/2+→13/2+) in 169Os, similar to the “anomalously” low values of the ratio B(E2;41+→21+)/B(E2;21+→0gs+) previously observed in several transitional rare-earth nuclides with even numbers of neutrons and protons, including the neighbouring 168,170Os. Furthermore, the evolution of B(E2;21/2+→17/2+)/B(E2;17/2+→13/2+) with increasing neutron number in the odd-mass isotopic chain 169,171,173Os is observed to follow the same trend as observed previously in the even-even Os isotopes. These findings indicate that the possible quantum phase transition from a seniority conserving structure to a collective regime as a function of neutron number suggested for the even-even systems is maintained in these odd-mass osmium nuclei, with the odd valence neutron merely acting as a “spectator”. As for the even-even nuclei, the phenomenon is highly unexpected for nuclei that are not situated near closed shells.

Item Type: Article
Divisions: Faculty of Science and Engineering > School of Physical Sciences
Depositing User: Symplectic Admin
Date Deposited: 16 Dec 2021 13:13
Last Modified: 16 Oct 2023 18:01
DOI: 10.1016/j.physletb.2021.136527
Open Access URL: https://www.sciencedirect.com/science/article/pii/...
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URI: https://livrepository.liverpool.ac.uk/id/eprint/3145490