Isospin mixing and in-beam study of non-yrast states in Co-56

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In the present work we have studied the fusion-evaporation 56Fe(p,n gamma)56Co reaction with an incident 10 MeV proton-beam at the Maier-Leibnitz-Laboratory (MLL) of the Technische Universität München (TUM, Germany). The gamma-rays emitted in the de-excitation of the odd-odd 56Co nucleus were measured in-beam with four high-resolution MINIBALL-triple germanium (Ge) detectors. The experiment provided excellent data in gamma-gamma coincidences. A total of 223 gamma-transitions have been observed and placed in the level scheme, 169 of which were previously unobserved. A total of 77 excited states have been observed: 37 of them were previously known states for which no gamma-de-excitation had been observed and 14 of them have been observed in this work for the first time. In 42 cases the precision of the excitation energy has been improved. The spin and parity assignments to the excited states were made based on their gamma-decay pattern and the angular distributions of the gamma-ray de-excitations measured. The angular distributions of 53 gamma-transitions were measured, obtaining the corresponding angular coefficients A2. A total of 36 new J-pi assignments have been made, 10 improvements of previous J-pi assignments have been suggested and in 4 cases J-pi assignments ambiguities have been resolved. For the remainder of states, previously assigned J-pi values have been confirmed. Large-scale shell-model calculations in a truncated fp-shell valence space were performed, using the NuShellX@MSU and ANTOINE codes with the KB3G, GXPF1a and KB3GR effective interactions, to compare with the experimental results.
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