Evolution of nuclear structure in the neutron-rich 96,97,99Nb isotopes: Evidence for shape coexistence in N=58 99Nb

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dc.authoridO'Donnell, David/0000-0002-4710-3803
dc.contributor.authorKumar, V.
dc.contributor.authorChapman, R.
dc.contributor.authorO'Donnell, D.
dc.contributor.authorOllier, J.
dc.contributor.authorOrlandi, R.
dc.contributor.authorSmith, J. F.
dc.contributor.authorSpohr, K. -m.
dc.date.accessioned2025-03-17T12:25:43Z
dc.date.available2025-03-17T12:25:43Z
dc.date.issued2023
dc.departmentTarsus Üniversitesi
dc.description.abstractExcited states of the neutron-rich niobium isotopes 96,97,98,99 41Nb have been populated in two experiments which used fusion-fission and multinucleon binary grazing reactions to populate high-spin yrast states. In the multinucleon-transfer experiment, a 530-MeV beam of 96Zr ions was incident on a thin 124Sn target; projectile-like ejectiles were detected and identified using the PRISMA magnetic spectrometer and the associated gamma rays were detected using the CLARA array of Ge detectors. In the second experiment, the GASP array of escape-suppressed Ge detectors was used to detect gamma rays from fusion-fission products formed following the interaction of a 230-MeV beam of 36S ions with a thick target of 176Yb. Level schemes of 96,97,99Nb were established up to excitation energies of 4545, 5409, and 3814 keV, respectively; states with proposed spin values up to about 15 h over bar were populated. Gamma-ray photopeaks corresponding to transitions in 98Nb were also observed in the PRISMA-CLARA experiment; however, it was not possible, in this case, to produce a level scheme based on gamma-ray coincidence data from the GASP experiment. For 96Nb and 97Nb, the level schemes are in agreement with the results of earlier publications. Two new decay sequences have been populated in 99Nb; tentative J pi values of the hitherto unobserved states have been assigned through comparisons with J pi values of neighboring nuclei. In contrast with earlier published studies of the high-spin spectroscopy of 96Nb and 97Nb, the present work provides an unambiguous association of the observed gamma rays with the A and Z of the excited nucleus. The structure of the yrast states of 96,97,99Nb is discussed within the context of shell-model calculations. The experimental results, supported by model calculations, indicate the first observation of shape coexistence at low spin and low excitation energy in the N = 58 nucleus 99Nb. The results of TRS calculations indicate that the 9/2+ ground state is triaxial, tending to oblate shapes with a transition to a more deformed prolate shape beyond the 17/2+ member of the decay sequence; here the sequence has been observed to (29/2+). On the other hand, the previously unobserved decay sequence based on the 5/2- state at 631 keV exhibits the characteristics of a rotational sequence and has been assigned Nilsson quantum numbers 5/2-[303]. TRS calculations indicate that the 5/2-[303] band is gamma soft and this is consistent with the inability of the particle-rotor model to reproduce the observed behavior of the signature-splitting function.
dc.description.sponsorshipUK Science and Technology Facilities Council (STFC) [ST/V001124/1, ST/P005101/1]; Romanian Ministry of Research, Innovation, and Digitalisation [PN23210105]; STFC [ST/V001124/1, ST/P005101/1] Funding Source: UKRI
dc.description.sponsorshipThe authors thank I. Ragnarsson for very helpful discussions in relation to the particle rotor calculations performed here. This work was supported by the UK Science and Technology Facilities Council (STFC) under Grants No. ST/V001124/1 (UWS) and No. ST/P005101/1 (UWS) . In addition, the work was supported by the PN23210105 contract sponsored by the Romanian Ministry of Research, Innovation, and Digitalisation and by the IOSIN funds for research infrastructures of Romanian national interest. Finally, the contribution of the accelerator and target-fabrication staff at the INFN Legnaro National Laboratory is gratefully acknowledged.
dc.identifier.doi10.1103/PhysRevC.108.044313
dc.identifier.issn2469-9985
dc.identifier.issn2469-9993
dc.identifier.issue4
dc.identifier.scopus2-s2.0-85175440675
dc.identifier.scopusqualityQ1
dc.identifier.urihttps://doi.org/10.1103/PhysRevC.108.044313
dc.identifier.urihttps://hdl.handle.net/20.500.13099/1822
dc.identifier.volume108
dc.identifier.wosWOS:001106462600001
dc.identifier.wosqualityQ2
dc.indekslendigikaynakWeb of Science
dc.indekslendigikaynakScopus
dc.language.isoen
dc.publisherAmer Physical Soc
dc.relation.ispartofPhysical Review C
dc.relation.publicationcategoryMakale - Uluslararası Hakemli Dergi - Kurum Öğretim Elemanı
dc.rightsinfo:eu-repo/semantics/openAccess
dc.snmzKA_WOS_20250316
dc.subjectProton Hole States
dc.subjectHigh-Spin States
dc.subjectLow-Lying States
dc.subjectData Sheets
dc.subjectRotational Bands
dc.subjectShell-Model
dc.subjectDeformation
dc.subjectNb-96
dc.subjectDetector
dc.subjectGamma
dc.titleEvolution of nuclear structure in the neutron-rich 96,97,99Nb isotopes: Evidence for shape coexistence in N=58 99Nb
dc.typeArticle

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