Testing interacting boson model cores through particle-core coupling: Negative parity states in the odd-mass Tl and Au isotopes

Particle-core coupling calculations have been made for the h9/2 bands in the odd-Tl isotopes (A=191197) and the h11/2 bands in the odd-Au isotopes (A=189195). The even-mass Hg core descriptions were taken from previous proton-neutron interacting boson model calculations, and thus a comparison between the experimental and calculated level schemes for the Tl and Au isotopes can be interpreted as a test of the core description. A predicted transition from positive Q(2+) near A=195 to negative Q(2+) near A=191 is not borne out by the odd-A data. These results, combined with new proton-neutron interacting boson model calculations, indicate that the Hg isotopes are more U(5) than O(6) in character.