Lifetimes and shape-coexisting states of Zr 99

P. Spagnoletti, G. Simpson, S. Kisyov, D. Bucurescu, J. M. Régis, N. Saed-Samii, A. Blanc, M. Jentschel, U. Köster, P. Mutti, T. Soldner, G. De France, C. A. Ur, W. Urban, A. M. Bruce, C. Bernards, F. Drouet, L. M. Fraile, L. P. Gaffney, D. G. GhitǎS. Ilieva, J. Jolie, W. Korten, T. Kröll, S. Lalkovski, C. Larijarni, R. Licǎ, H. Mach, N. Mǎrginean, V. Paziy, Zs Podolyák, P. H. Regan, M. Scheck, J. F. Smith, G. Thiamova, C. Townsley, A. Vancraeyenest, V. Vedia, N. Warr, V. Werner, M. Zielińska

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Abstract

Lifetimes of intermediate-spin states in two rotational bands of Zr99 have been measured. These states were populated following the neutron-induced fission of U235 at the PF1B beamline of the Institut Laue-Langevin, Grenoble, during the EXILL-FATIMA campaign. The nucleus Zr9959 exhibits shape coexistence and lies precisely on the border of an abrupt change in ground-state deformation when going from N=58 to N=60, making its study interesting for understanding the mechanisms involved in the rapid onset of deformation here. The B(E2) values extracted for decays in the ν3/2[541] band allow quadrupole deformations of β2=0.34(1) and 0.26(3) to be determined for the 821.6- and 1236.6-keV members, whereas β2=0.32(3) was found for the 850.5-keV member of the ν3/2[411] band. Some of the excited states known in Zr99 have been reasonably described with interacting boson-fermion model (IBFM) calculations. Type-II shell evolution is proposed to play a major role in modifying single-particle energies in Zr99.

Original languageEnglish
Article number014311
JournalPhysical Review C
Volume100
Issue number1
DOIs
Publication statusPublished - 16 Jul 2019

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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

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Spagnoletti, P., Simpson, G., Kisyov, S., Bucurescu, D., Régis, J. M., Saed-Samii, N., ... Zielińska, M. (2019). Lifetimes and shape-coexisting states of Zr 99. Physical Review C, 100(1), [014311]. https://doi.org/10.1103/PhysRevC.100.014311