The structure of neutron-rich nuclei beyond 78Ni was studied using postaccelerated radioactive beams of 83,84,85Ga utilizing β γ and β-n γ spectroscopy. Our data, when combined with energy level systematics, suggests a possible new spherical subshell closure at N=58 is created by the nearly degenerated ν3s1/2 and ν2d5/2 orbitals being well separated from other orbitals above N=50. The near degeneracy of these states could be evidenced by isomerism in this region. The energies of the 21+ and proposed 41+ states observed in N=52 84Ge are interpreted as an indication of a possible weakening of the doubly magic 78Ni core for nuclei beyond N=50. The experimental evidence is supported by spherical HFB calculations using the SkOT functional involving the tensor term in the nucleon-nucleon interaction.
New shell closure at N=58 emerging in neutron-rich nuclei beyond 78Ni / J. A. Winger, K. P. Rykaczewski, C. J. Gross, R. Grzywacz, J. C. Batchelder, C. Goodin, J. H. Hamilton, S. V. Ilyushkin, A. Korgul, W. Kŕolas, S. N. Liddick, C. Mazzocchi, S. Padgett, A. Piechaczek, M. M. Rajabali, D. Shapira, E. F. Zganjar, J. Dobaczewski. - In: PHYSICAL REVIEW. C, NUCLEAR PHYSICS. - ISSN 0556-2813. - 81:4(2010). [10.1103/PhysRevC.81.044303]
New shell closure at N=58 emerging in neutron-rich nuclei beyond 78Ni
C. Mazzocchi;
2010
Abstract
The structure of neutron-rich nuclei beyond 78Ni was studied using postaccelerated radioactive beams of 83,84,85Ga utilizing β γ and β-n γ spectroscopy. Our data, when combined with energy level systematics, suggests a possible new spherical subshell closure at N=58 is created by the nearly degenerated ν3s1/2 and ν2d5/2 orbitals being well separated from other orbitals above N=50. The near degeneracy of these states could be evidenced by isomerism in this region. The energies of the 21+ and proposed 41+ states observed in N=52 84Ge are interpreted as an indication of a possible weakening of the doubly magic 78Ni core for nuclei beyond N=50. The experimental evidence is supported by spherical HFB calculations using the SkOT functional involving the tensor term in the nucleon-nucleon interaction.Pubblicazioni consigliate
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