Lifetime measurements of excited states in Os-169,Os-171,Os-173: Persistence of anomalous B(E2) ratios in transitional rare earth nuclei in the presence of a decoupled i(13/2) valence neutron

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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) , Hodge, D, Giles, M, Stolze, S, Badran, H, Braunroth, T, Calverley, T, Cox, DM, Fang, YD, Greenlees, PT, Hilton, J, Ideguchi, E, Julin, R, Juutinen, S, Raju, M Kumar, Li, H, Liu, H, Matta, S, Subramaniam, P, Modamio, V, Pakarinen, J, Papadakis, P ORCID: 0000-0001-7509-4257, Partanen, J, Petrache, CM, Rahkila, P, Ruotsalainen, P, Sandzelius, M, Saren, J, Scholey, C, Sorri, J, Taylor, MJ, Uusitalo, J and Valiente-Dobon, JJ (2021) Lifetime measurements of excited states in Os-169,Os-171,Os-173: Persistence of anomalous B(E2) ratios in transitional rare earth nuclei in the presence of a decoupled i(13/2) 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:	18 Jan 2023 21:19
DOI:	10.1016/j.physletb.2021.136527
Open Access URL:	https://www.sciencedirect.com/science/article/pii/...
Related URLs:	Author Publisher
URI:	https://livrepository.liverpool.ac.uk/id/eprint/3145490