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Nuclear spins, magnetic moments and α-decay spectroscopy of long-lived isomeric states in 185Pb

  • A.N. Andreyev
  • K. Van de Vel
  • A. Barzakh
  • A. De Smet
  • H. De Witte
  • D.V. Fedorov
  • V.N. Fedoseyev
  • S. Franchoo
  • M. Górska
  • M. Huyse
  • Z. Janas
  • U. Köster
  • W. Kurcewicz
  • J. Kurpeta
  • V.I. Mishin
  • K. Partes
  • A. Plochocki
  • P. Van Duppen
  • L. Weissman

Abstract:

Alpha-decay properties of the neutron-deficient isotope 185Pb were studied at the PSB-ISOLDE (CERN) on-line mass separator using the resonance ionisation laser ion source (RILIS). The nuclei of interest were produced in a 1.4 GeV proton-induced spallation reaction of a uranium graphite target. In contrast to previous studies, two α-decaying isomeric states were identified in 185Pb. The relative production of the isomers, monitored by their α-counting rates, could be significantly changed when a narrow-bandwidth laser at the RILIS setup was used to scan through the atomic hyperfine structure. Based on the atomic hyperfine structure measurements, along with the systematics for heavier odd-mass lead isotopes, the spin and the parity of these states were interpreted as 3/2- and 13/2+ and their nuclear magnetic moments were deduced. The α-decay energy and half-life value for the Iπ = 13/2+ isomer are Eα = 6408(5) keV, T1/2 = 4.3(2) s, respectively; while for the Iπ = 3/2- isomer ( T1/2 = 6.3(4) s) two α-decays with Eα1 = 6288(5) keV, Iα1 = 56(2)% and Eα2 = 6486(5) keV, Iα2 = 44(2)% were observed. By observing prompt α-γ coincidences new information on the low-lying states in the daughter isotope 181Hg was obtained.

PACS. 27.70.+q 150 ?A? 189 – 23.60.+e Alpha decay – 32.10.Dk Electric and magnetic moments, polarizability – 32.10.Fn Fine and hyperfine structure 

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Copyright information

© Società Italiana di Fisica and Springer-Verlag 2002

Authors and Affiliations

  • A.N. Andreyev
    • 1
  • K. Van de Vel
    • 2
  • A. Barzakh
    • 3
  • A. De Smet
    • 2
  • H. De Witte
    • 2
  • D.V. Fedorov
    • 3
  • V.N. Fedoseyev
    • 4
  • S. Franchoo
    • 5
  • M. Górska
    • 2
  • M. Huyse
    • 2
  • Z. Janas
    • 6
  • U. Köster
    • 5
  • W. Kurcewicz
    • 6
  • J. Kurpeta
    • 6
  • V.I. Mishin
    • 4
  • K. Partes
    • 5
  • A. Plochocki
    • 6
  • P. Van Duppen
    • 2
  • L. Weissman
    • 5
  1. 1.Department of Physics, Oliver Lodge Laboratory, University of Liverpool, PO Box 147, Liverpool, L69 7ZE, United KingdomGB
  2. 2.Instituut voor Kern- en Stralingsfysica, University of Leuven, Celestijnenlaan 200 D, B-3001 Leuven, BelgiumBE
  3. 3.Petersburg Nuclear Physics Institute, 188300, Gatchina, RussiaRU
  4. 4.Institute of Spectroscopy, Russian Academy of Sciences, 142190, Troitsk, RussiaRU
  5. 5.ISOLDE CERN, CH-1211 Genève 23, SwitzerlandCH
  6. 6.Institute of Experimental Physics, University of Warsaw, Hoza 69, PL-00681, Warsaw, Poland IS387 Collaboration and ISOLDE CollaborationPL

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