Long-lived isomers in ¹⁹⁰Ir

Abstract

Long-lived isomeric states in ¹⁹⁰Ir have been investigated with the ¹⁹²Os(p,3n) ¹⁹⁰Ir and ¹⁹²Os(d,4n) ¹⁹⁰Ir reactions using beams of 18–31 MeV protons and 27.8 MeV deuterons, respectively. A series of measurements, including excitation functions, half lives, e⁻γ coincidences and e⁻e⁻ coincidences, was performed. Five new transitions were observed, and the results of e⁻γ and e⁻e⁻ coincidences indicate that these transitions are fed by the 148.7 keV M4 transition that depopulates the 11⁻ isomer. The previous decay scheme is shown to be incorrect, and the results allow the ground state parity and mass excess to be determined.