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Abstract

A comprehensive study of the isotope ¹⁷⁸Au has been made at the CERN-ISOLDE facility, using resonance laser ionization. Two long-lived states in ¹⁷⁸Au were identified—a low-spin ground state and a high-spin isomer—each of which were produced as pure beams. Using the ISOLTRAP precision Penning trap, the excitation energy of the isomeric state in 178Au was determined to be E∗=189(14)keV. The α-decay fine structure patterns of the two states were studied using the Windmill decay station, providing information on the low-lying states in the daughter nucleus ¹⁷⁴Ir. Nuclear spin assignments of I(¹⁷⁸Au^g)=(2,3) and I(¹⁷⁸Au^m)=(7,8) are made based on the observed β-decay feeding and hyperfine structure intensity patterns. These spin assignments are used for fitting the hyperfine structures of the two states from which values for the magnetic dipole moments are extracted. The extracted moments are compared with calculations using additivity relations to establish the most probable configurations for ¹⁷⁸Au^g,m.