Rotational bands in the doubly magic nucleus Ni-56

Structures of the medium- to high-spin states in the doubly magic nucleus N i-56 have been investigated using the reaction Si-28(Ar-36, 2 alpha) and th e gamma-ray spectrometer Gammasphere in conjunction with the 4 pi charged-p article detector array Microball. Two well-deformed rotational bands have b een identified. There is evidence that one of the bands, which is identical to a sequence in the odd-odd neighbor Cu-58, partially decays via proton e mission into the ground state of Co-55. Predictions of extensive large-scal e shell-model and cranked Hartree-Fock and Hartree-Fock-Bogolyubov calculat ions are compared with the experimental data.