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The odd-odd 88 37Rb51 and 86 35Br51 nuclei have been produced as fission fragments in the fusion reaction 18O$ + $208Pb at 85MeV bombarding energy and studied with the Euroball IV array. Their high-spin level schemes have been built from the triple $ \gamma$ -ray coincidence data and $ \gamma$ - $ \gamma$ angular correlations have been analyzed in order to assign spin and parity values to many observed states. The proposed configurations involve proton excitations from three sub-shells located close to the Fermi levels, $ \pi$ p3/2 , $ \pi$ f5/2 , and $ \pi$ g9/2 , the $ \nu$ d5/2 neutron acting as a spectator. The residual $ \pi$ $ \nu$ interactions are extracted from the multiplets of states resulting from the $ \pi$ p3/2 $ \nu$ d5/2 and $ \pi$ f5/2 $ \nu$ d5/2 configurations. The empirical values of the latter are discussed and compared to those known in two similar configurations having jp = jn with lp = ln + 1 , where the role of the tensor force had been highlighted. [ABSTRACT FROM AUTHOR]

The 81, 82, 83, 85Se nuclei have been produced as fission fragments in the fusion reaction 18O + 208Pb at 85MeV bombarding energy and studied with the Euroball IV array. Their high-spin level schemes have been built from the triple $ \gamma$ -ray coincidence data and $ \gamma$ - $ \gamma$ angular correlations have been analyzed in order to assign spin and parity values to many observed states. The lowest-spin states of the two-neutron and three-neutron configurations are strongly mixed with two-proton excitations among the fp orbits. On the other hand, the highest-spin states of these neutron configurations are found to remain almost pure. Neutron excitation across the N = 50 gap is observed both in 83Se49 and in 85Se51 . [ABSTRACT FROM AUTHOR]

The84Se nucleus has been produced as fission fragment in the fusion reaction18O +208Pb at 85MeV bombarding energy and studied with the Euroball IV array. Medium-spin states of this neutron-rich isotope have been identified for the first time. Its level scheme has been obtained up to 4.9MeV excitation energy and spinI~ 7?. Its structure is interpreted by analogy with those of the stable heavier isotones. The evolution of the energy of theN= 50 neutron-core excitation is discussed as a function of the proton number. [ABSTRACT FROM AUTHOR]

High-spin states in 108,110Pd isotopes are studied by γ-ray spectroscopy of heavy-ion-induced fission. The Pd isotopes are produced in the fission channel of the 31P + 176Yb reaction at beam energy 152 MeV. The prompt γ-rays are detected with the EUROBALL4 multidetector array. The yrast states of 108,110Pd have been observed above the region of the first backbend. The level scheme of 108Pd was extended with a new negative-parity band. The yrast sequence in 110Pd is observed up to spin I = 14+ and negative-parity bands have also been identified. The back bending in these even-mass Pd isotopes is associated with the alignment of the neutron (h11/2)² pair. The negative-parity states arise from two neutron configurations vh11/2 ⊗ vg7/2 and vh11/2 ⊗ vd5/2 and they are interpreted in the frame of two-quasiparticle + rotor model as semidecoupled bands. The observed experimental staggering in the γ-bands of 108,110Pd supports the theoretical predictions for γ-instability of their shapes. [ABSTRACT FROM AUTHOR]