Shape Isomerism at N = 40: Discovery of a Proton Intruder in 67Co

Abstract

The nuclear structure of 67Co has been investigated through 67Fe beta-decay. The 67Fe isotopes were produced at the LISOL facility in proton-induced fission of 238U and selected using resonant laser ionization combined with mass separation. The application of a new correlation technique unambiguously revealed a 496(33) ms isomeric state in 67Co at an unexpected low energy of 492 keV. A 67Co level scheme has been deduced. Proposed spin and parities suggest a spherical (7/2-) 67Co ground state and a deformed first excited (1/2-) state at 492 keV, interpreted as a proton 1p-2h prolate intruder state.

4 pages, 5 figures, preprint submitted to Physical Review Letters

Cited by in corpus (4)

• Discovery of a new isomeric state in ${}^{68}$Ni: Evidence for a highly-deformed proton intruder state
• Precision Mass Measurements of Neutron-Rich Co Isotopes Beyond N=40
• Shell-model results in $fp$ and $fp{g}_{9/2}$ spaces for ${}^{61,63,65}$Co isotopes
• Probing the role of proton cross-shell excitations in 70Ni using nucleon knockout reactions