First Observation of Excited States in ¹⁴⁰Dy

The mass A = 140 products of the ⁵⁴Fe (315 MeV) + ⁹²Mo reaction were selected by a recoil mass spectrometer and studied in a recoil ‐ delayed γ‐γ coincidence experiment. A new 7 μs isomer was identified in the drip line nucleus ¹⁴⁰Dy. Five cascading γ transitions were assigned to the decay of the I^π = 8⁻ {v9/2⁻[514] ⊗ v7/2⁺[404]} K isomer via the ground state band transitions. The established structure of ¹⁴⁰Dy is discussed with reference to the fine structure in proton decay of ¹⁴¹Ho.