One-proton and one-neutron knockout reactions from N=Z=28Ni56 to the A=55 mirror pair Co55 and Ni55

M. Spieker, A. Gade, D. Weisshaar, B. A. Brown, J. A. Tostevin, B. Longfellow, P. Adrich, D. Bazin, M. A. Bentley, J. R. Brown, C. M. Campbell, C. Aa. Diget (+6 others)
2019 Physical Review C  
We present a high-resolution in-beam γ-ray spectroscopy study of excited states in the mirror nuclei ^55Co and ^55Ni following one-nucleon knockout from a projectile beam of ^56Ni. The newly determined partial cross sections and the γ-decay properties of excited states provide a test of state-of-the-art nuclear structure models and probe mirror symmetry in unique ways. A mirror asymmetry for the partial cross sections leading to the two lowest 3/2^- states in the A = 55 mirror pair was
more » ... d as well as a significant difference in the E1 decays from the 1/2^+_1 state to the same two 3/2^- states. The mirror asymmetry in the partial cross sections cannot be reconciled with the present shell-model picture or small mixing introduced in a two-state model. The observed mirror asymmetry in the E1 decay pattern, however, points at stronger mixing between the two lowest 3/2^- states in ^55Co than in its mirror ^55Ni.
doi:10.1103/physrevc.99.051304 fatcat:yzcwft3bgfar7lube3ojrqihtq