One-proton and one-neutron knockout reactions from $N=Z=28$ ${}^{56}$Ni to the $A=55$ mirror pair ${}^{55}$Co and ${}^{55}$Ni

Abstract

We present a high-resolution in-beam $\gamma$-ray spectroscopy study of excited states in the mirror nuclei ${}^{55}$Co and ${}^{55}$Ni following one-nucleon knockout from a projectile beam of ${}^{56}$Ni. The newly determined partial cross sections and the $\gamma$-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 identified 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 ${}^{55}$Co than in its mirror ${}^{55}$Ni.

References in corpus (18)

• New effective interaction for $pf$-shell nuclei and its implications for the stability of the $N$=$Z$=28 closed core
• Effective interaction for pf-shell nuclei
• Systematics of intermediate-energy single-nucleon removal cross sections
• Isobaric multiplet yrast energies and isospin non-conserving forces
• Dynamics of nuclear single-particle structure in covariant theory of particle-vibration coupling: from light to superheavy nuclei
• Role of Long-Range Correlations on the Quenching of Spectroscopic Factors
• In-Medium Similarity Renormalization Group for Closed and Open-Shell Nuclei
• Magnetic dipole moment of 57,59Cu measured by in-gas-cell laser spectroscopy
• Emergent properties of nuclei from ab initio coupled-cluster calculations
• Quasiparticle and quasihole states of nuclei around 56Ni
• Neutron spectroscopic factors of Ni isotopes from transfer reactions
• Mirror Energy Differences at Large Isospin Studied through Direct Two-Nucleon Knockout
• One-neutron knockout from ${}^{57}$Ni
• Shape coexistence and isospin symmetry in $A=70$ nuclei: Spectroscopy of the $T_z=-1$ nucleus ${}^{70}$Kr
• Spectroscopy of ${}^{35}$P using the one-proton knockout reaction
• Doubly-magic nature of 56Ni: measurement of the ground state nuclear magnetic dipole moment of 55Ni
• Neutron spectroscopic factors of ${}^{55}$Ni hole-states from (p,d) transfer reactions
• Isospin Symmetry violation in mirror E1 transitions: Coherent contributions from the Giant Isovector Monopole Resonance in 67As - 67Se

Cited by in corpus (6)

• Quenching of single-particle strength from direct reactions with stable and rare-isotope beams
• On the inversion of isobaric-analogue states in nuclei
• The Structure of ${}^{33}$Si and the magicity of the N=20 gap at Z=14
• Exploiting dissipative reactions to perform in-beam $\gamma$-ray spectroscopy of the neutron-deficient isotopes \nuc{38,39}{Ca}
• Experimental identification of the $T=1$, $J^{\pi }=6^{+}$ state of ${}^{54}$Co and isospin symmetry in $A=54$ studied via one-nucleon knockout reactions
• Proton removal from ${}^{73,75}$Br to ${}^{72,74}$Se at intermediate energies