High-Precision Mass Measurements of 52Ni and 51Co Reveal Breakdown of the Isobaric Multiplet Mass Equation in the f p Shell

We performed high-precision mass measurements of the proton-rich nuclei $^{52}$Ni and $^{51}$Co with the LEBIT Penning trap at the Facility for Rare Isotope Beams (FRIB). For $^{52}$Ni, a mass excess of $-22474.8(2.2)$~keV was determined, which is consistent with a recent storage-ring measurement at