Observation of the N = Z=44 88Ru nucleus -: art. no. 031303

Four gamma -ray transitions belonging to the ground state band of the N = Z nucleus Ru-88 reported for the first time. The reaction Ni-58(S-32,2n gamma) at 105 MeV has been used, and the prompt gamma rays were detected with the GASP array. The assignment of gamma rays to Ru-88 was made by combining information from GASP. the ISIS silicon ball, and the n-Ring neutron detector. The Ru-88 nucleus is weakly deformed, with an E(2(+)) energy of 0.616 MeV and E(4(+))/E(2(+)) ratio of 2.30. The evolution of the nuclear structure along the N = Z, N = 44, and Z = 44 lines is discussed. Unlike in other nuclei from the region, no sign of backbending is seen in Ru-88 at a rotational frequency of approximate to0.5 MeV, which might be a signature of the T = 0 neutron-proton pairing in the N = Z nuclei.