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Type II shell evolution in A=70 isobars from the N≥40 island of inversion

Journal Contribution - Journal Article

The level structures of 70Co and 70Ni, populated from the β decay of 70Fe, have been investigated using β-delayed γ-ray spectroscopy following in-flight fission of a 238U beam. The experimental results are compared to Monte-Carlo Shell-Model calculations including the pf+g9/2+d5/2 orbitals. The strong population of a (1+) state at 274 keV in 70Co is at variance with the expected excitation energy of ∼1 MeV from near spherical single-particle estimates. This observation indicates a dominance of prolate-deformed intruder configurations in the low-lying levels, which coexist with the normal near spherical states. It is shown that the β decay of the neutron-rich A=70 isobars from the new island of inversion to the Z=28 closed-shell regime progresses in accordance with a newly reported type of shell evolution, the so-called Type II, which involves many particle-hole excitations across energy gaps.
Journal: Physics Letters B
ISSN: 0370-2693
Volume: 765
Pages: 328 - 333
Publication year:2017
BOF-keylabel:yes
IOF-keylabel:yes
BOF-publication weight:3
CSS-citation score:2
Authors:International
Authors from:Higher Education
Accessibility:Open