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Open Access Publications from the University of California

New low-energy 0+ state and shape coexistence in Ni 70

  • Author(s): Prokop, CJ
  • Crider, BP
  • Liddick, SN
  • Ayangeakaa, AD
  • Carpenter, MP
  • Carroll, JJ
  • Chen, J
  • Chiara, CJ
  • David, HM
  • Dombos, AC
  • Go, S
  • Harker, J
  • Janssens, RVF
  • Larson, N
  • Lauritsen, T
  • Lewis, R
  • Quinn, SJ
  • Recchia, F
  • Seweryniak, D
  • Spyrou, A
  • Suchyta, S
  • Walters, WB
  • Zhu, S
  • et al.

© 2015 American Physical Society. In recent models, the neutron-rich Ni isotopes around N=40 are predicted to exhibit multiple low-energy excited 0+ states attributed to neutron and proton excitations across both the N=40 and Z=28 shell gaps. In Ni68, the three observed 0+ states have been interpreted in terms of triple shape coexistence between spherical, oblate, and prolate deformed shapes. In the present work a new (02+) state at an energy of 1567 keV has been discovered in Ni70 by using β-delayed, γ-ray spectroscopy following the decay of Co70. The precipitous drop in the energy of the prolate-deformed 0+ level between Ni68 and Ni70 with the addition of two neutrons compares favorably with results of Monte Carlo shell-model calculations carried out in the large fpg9/2d5/2 model space, which predict a 02+ state at 1525 keV in Ni70. The result extends the shape-coexistence picture in the region to Ni70 and confirms the importance of the role of the tensor component of the monopole interaction in describing the structure of neutron-rich nuclei.

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