An IBM description of coexistence in the platinum isotopes

The available data on the light platinum isotopes have, until now, lacked calculations which reproduce them. A configuration-mixing calculation is presented which describes these nuclei in terms of a normal (near-spherical) and a deformed configuration, the latter becoming the ground configuration near neutron mid-shell. The deformed configuration is modelled as a proton pair excitation across the Z = 82 shell gap within the Interacting Boson Model, and allowed to mix with the normal configuration. The systematics of level energies, electromagnetic transition rates and moments, isotope and isomer shifts are studied. The latter are shown to be sensitive probes of the configuration-mixing strength.