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

M. Spieker; D. Weisshaar; A. Gade; B. A. Brown; P. Adrich; D. Bazin; M. A. Bentley; J. R. Brown; C. M. Campbell; C. Aa. Diget; B. Elman; T. Glasmacher; M. Hill; B. Longfellow; B. Pritychenko; A. Ratkiewicz; D. Rhodes; J. A. Tostevin

doi:10.1103/physrevc.100.061303

arXiv · 2003.10363

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

M. Spieker·D. Weisshaar·A. Gade·B. A. Brown·P. Adrich·D. Bazin·M. A. Bentley·J. R. Brown·C. M. Campbell·C. Aa. Diget·B. Elman·T. Glasmacher·M. Hill·B. Longfellow·B. Pritychenko·A. Ratkiewicz·D. Rhodes·J. A. Tostevin

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Abstract

New experimental data obtained from $\gamma$-ray tagged one-neutron and one-proton knockout from $^{55}$Co is presented. A candidate for the sought-after $T=1, T_z = 0, J^{\pi} = 6^+$ state in $^{54}$Co is proposed based on a comparison to the new data on $^{54}$Fe, the corresponding observables predicted by large-scale-shell-model (LSSM) calculations in the full $fp$-model space employing charge-dependent contributions, and isospin-symmetry arguments. Furthermore, possible isospin-symmetry breaking in the $A=54$, $T=1$ triplet is studied by calculating the experimental $c$ coefficients of the isobaric mass multiplet equation (IMME) up to the maximum possible spin $J=6$ expected for the $(1f_{7/2})^{-2}$ two-hole configuration relative to the doubly-magic nucleus $^{56}$Ni. The experimental quantities are compared to the theoretically predicted $c$ coefficients from LSSM calculations using two-body matrix elements obtained from a realistic chiral effective field theory potential at next-to-next-to-next-to-leading order (N$^3$LO).

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M. Spieker, D. Weisshaar, A. Gade, B. A. Brown, P. Adrich, D. Bazin, M. A. Bentley, J. R. Brown, C. M. Campbell, C. Aa. Diget, B. Elman, T. Glasmacher, M. Hill, B. Longfellow, B. Pritychenko, A. Ratkiewicz, D. Rhodes, J. A. Tostevin. 2020-03-23. 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. https://doi.org/10.1103/physrevc.100.061303

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