Identification of T=0 and T=1 bands in the N=Z=37 nucleus 74Rb.

The gamma decay of excited states in the N = Z odd-odd nucleus Rb-74 has been observed for the first time. The reaction Ca-40(Ca-40,alpha pn)Rb-74 at 128 MeV beam energy was used. The ground state rotational band can be interpreted as being formed from the T = 1 isobaric analog states of Kr-74 with pairing correlations based on T = 1, M(T) = 0 neutron-proton pairs. At higher rotational frequency, a T = 0 rotational band becomes energetically favored over the T = 1 ground state band, in agreement with the predictions of cranked shell model calculations which explicitly include T = 0 and T = 1 pairs.