Positive- and negative-parity level structures of Pt194 from n,n′γ reaction spectroscopy

Energy levels of Pt194 populated by the (n,n′γ) reaction have been studied at incident neutron energies up to 4.5 MeV. Detailed γ-ray excitation functions were measured between 1.4 and 2.5 MeV, and γ-ray angular distributions were obtained at 2.5 MeV. Essentially all previously known levels below 2.0 MeV having J≤6 were observed. New level placements and spins for some previously unassigned levels have been deduced. The negative-parity states with spins from 1- to 6- are interpreted in terms of the semi-decoupled model. The positive-parity states are compared to several models, including the boson expansion theory and the interacting boson model. The interacting boson model adequately accounts for the observed branching ratios, with the exception of the previously noted anomalous 1547-keV 0+ state. The boson expansion theory enjoys comparable success for Pt194. NUCLEAR REACTIONS Pt194(n,n′γ), En=1.2-4.5 MeV. Measured Eγ, Iγ, σ(E,Eγ,θγ), Pt194 deduced levels, branching ratios, J, π. Compared levels and branching ratios to theory. Enriched target, Ge(Li) detector, time-of-flight background suppression.