Structure of the neutron-deficient nuclei 173Au and 173Pt and their α-decay descendants

Fusion-evaporation reactions have been used to populate excited states in 173Au and 173Pt, and expand the level schemes for these nuclei. Transitions feeding the π −1 (s1/2) state in 173Au have been discovered for the first time. No collective behaviour was observed in 173Au either. Although no evidence of isomeric transitions or fine structure was present for the decay chain of 173Au, an isomeric transition in 173Pt was observed for the first time. It was found to be decaying from 173Pt’s ν(i13/2) band head to the ν(h9/2) band head. The excitation energy of both of these bands have been determined for the first time. The ν(h9/2) feeds the ground state via decay of a 104-keV γ ray. The ground state of 173Pt has been established to be ν(f7/2). These new findings were compared to systematic trends for both the Pt and Au isotopes. α-decay analysis of 173Pt suggests a ν(f7/2) ground state for the daughter nucleus 169Os, with the 35-keV (5/2−), 112-keV (9/2−), 136-keV and 171-keV states being populated via fine structure of 173Pt’s α decay. The α-decay chains originating from the isomeric π −1 (h11/2 ) state and the π −1 (s1/2) ground state have been studied, culminating in the observation of the α decay of 161Ta m and 165Re g, respectively. As well as reporting a new activity in the decay of 165Re g and confirming that the known α decay of 161Ta is associated with the high-spin isomer, this work has allowed the excitation energy of the high-spin state of 161Ta to be determined for the first time. In combining these new measurements with the information already available on 157Lu Qα -value for the decay of the ground state of 161Ta it has also been possible to deduce the 161Ta. This has enabled the Qp -values of to be measured to give -129(24)keV and -37(21)keV for the ground and isomeric state, respectively, indicating that these states are only just bound with respect to proton emission. The nuclear masses were deduced from Qα measurements in this work and were found to be consistent with values obtained from more direct methods, such as Schottky mass spectrometry or Penning trap mass spectrometry