Low-lying levels, γ-ray transitions, and vibrational structure in 198Pt from (n,n'γ) reaction spectroscopy

Low-lying states in 198Pt have been studied by (n, n'γ) reaction spectroscopy at incident neutron energies below 2.5 MeV. Using detailed γ-ray excitation functions and angular distribution measurements, we have established a level scheme which includes 16 excited levels and is believed to include all levels below an excitation energy of 1.5 MeV. The positive-parity structure is similar to that expected for an anharmonic vibrator; however, difficulties in asserting that the first 0+ excited level is a collective excitation are encountered. Only two negative-parity states are observed, and they are adequately described in the semi-decoupled model. (orig.)