Published August 2006 | Version v1
Journal article

Magicity and occurrence of a band with enhanced B(E2) in neutron-rich nuclei 68Ni and 90Zr

  • 1. Department of Physics, Kyushu Sangyo University, Fukuoka 813-8503 (Japan)
  • 2. Laboratory of Physics, Fukuoka Dental College, Fukuoka 814-0193 (Japan)
  • 3. Center for Nuclear Study (CNS), University of Tokyo, Wako Campus of RIKEN, Wako 351-0198 (Japan)
  • 4. Institute of Natural Sciences, Senshu University, Kawasaki, Kanagawa, 214-8580 (Japan)
  • 5. Department of Physics, Xuzhou Normal University, Xuzhou, Jiangsu 221009 (China)
  • 6. Department of Physics, Tsinghua University, Beijing 100084 (China)
  • 7. Department of Physics and Joint Institute for Nuclear Astrophysics, University of Notre Dame, Notre Dame, Indiana 46556 (United States)

Description

Experimental energy spectrum and B(E2) values in 68Ni and 90Zr indicate a double-magic character in these neutron-rich nuclei with N or Z=40. The data nevertheless do not show any pronounced irregularity in two-nucleon separation energy. To understand the underlying physics, we carry out both shell-model and mean-field calculations. The shell-model calculation can reproduce all the observations well. It is understood from the mean-field results for 68Ni that the shell gap at N=40 disappears because of dynamical correlations of the isovector J=0 pairing interaction. In 90Zr, however, such a dynamic process with the J=0 pairing appears not important because of the strong contribution of the J>0 interaction. We study also level schemes in the Ni isotopes and N= 50 isotones. We predict a new band built on the 02+ state in both 68Ni and 90Zr. The states of this band are dominated by two-particle-two-hole excitations from the fp shell to the intruder g9/2 orbit

Additional details

Publishing Information

Journal Title
Physical Review. C, Nuclear Physics
Journal Volume
74
Journal Issue
2
Journal Page Range
p. 024321-024321.10
ISSN
0556-2813
CODEN
PRVCAN

Optional Information

Notes
(c) 2006 The American Physical Society