Elsevier

Nuclear Physics A

Volume 484, Issue 2, 18 July 1988, Pages 337-375
Nuclear Physics A

Alternating parity bands and octupole effects in 221Th and 223Th★

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Abstract

Level structures of the two neutron deficient odd-A nuclei 221Th and 223Th have been investigated by means of the reactions 208Pb(16O, 3n)221Th and 208Pb(18O, 3n)223Th. In-beam conversion electron and γ-ray spectroscopy in coincidence with the recoiling evaporation residues (R) has been carried out, including γγR-, eγR- and eeR-coincidence measurements, as well as the determination of γ-ray angular distributions and γ-ray multiplicities using the Nal crystal ball. Level schemes could be established up to 13ħ above the ground state in 221Th and up to 33+2 in 223Th. In 221Th one band of alternating parity states is observed, whereas in 223Th two such bands with equal intensity are seen. The level schemes are interpreted in terms of an octupole deformed core with an unpaired nucleon. From the E1E2 branching ratio the electric dipole moments can be deduced; for 221Th one finds ¦D̄0¦ = 0.33 ± 0.06 e.fm and for 223Th ¦D̄0¦ = 0.44 ± 0.09 e.fm, the largest value observed so far in this mass region. The alignments of the different bands in 223Th with simplex quantum number s = ± i are approximately equal and amount to 〈i$̆= 3.7 ± 0.3 for the positive-parity bands, a value which is in accord with cranking calculations which assume octupole deformation.

References (48)

  • S.A. Ahmad et al.

    Phys. Lett.

    (1983)
  • R. Bengtsson et al.

    Nucl. Phys.

    (1979)
  • A. Bohr et al.

    Nucl. Phys.

    (1957)

    Nucl. Phys.

    (1959)
  • D.M. Brink et al.

    J. Phys.

    (1987)
  • P.D. Cottle et al.

    Phys. Rev.

    (1986)
  • M. Dahlinger et al.

    Z. Phys.

    (1985)
  • H.J. Daley et al.

    Phys. Lett.

    (1984)
  • R.M. Diamond et al.

    Phys. Rev. Lett.

    (1966)
  • M.W. Drigert et al.

    Phys. Rev.

    (1986)
  • H. Gröger et al.
  • G.A. Leander et al.

    Nucl. Phys.

    (1982)
  • G.A. Leander et al.

    Nucl. Phys.

    (1984)
  • G.A. Leander, private communication...
  • W. Nazarewicz et al.

    Phys. Rev. Lett.

    (1984)
  • W. Nazarewicz et al.

    Nucl. Phys.

    (1987)
  • G. Palameta et al.

    Nucl. Instr. Meth.

    (1985)
  • L.M. Robledo et al.

    Phys. Lett.

    (1987)
  • F. Rösel et al.

    At. Data Nucl. Data Tables

    (1978)
  • R.K. Sheline

    Phys. Lett.

    (1986)
  • J.F. Shriner et al.

    Phys. Rev.

    (1985)
  • V. Strutinski

    Atomnaya Energiya

    (1956)

    Journ. Nucl. Energy

    (1957)
  • H. Backe et al.

    Z. Phys.

    (1978)
  • W. Bonin et al.
  • Cited by (0)

    Darmstädter Dissertation D17.

    1

    Now at Universität Mainz, Institut für Physik, Postfach 3980, D-6500 Mainz, Germany.

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