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RESEARCH PRODUCT

Nuclear levels of 183W studied with and reactions

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Abstract The level structure of 183 W has been studied using gamma–gamma coincidences from thermal neutron capture in 182 W accompanied with the reaction ( d → , p ) . From these data and those of previous studies a total of 76 levels and about 490 connecting γ -transitions have been established for energies below 2.4 MeV. An analysis based on the standard distorted-wave Born approximation (DWBA) provides the lj -angular momentum transfers and spectroscopic factors for 36 levels up to 2.2 MeV excitation energy. A large number of particle transitions indicate an influence of strong mixing between particle and probably hole states. The extra exchange of phonons across the Fermi surface leads to a fine structure in the fragmentation of most single particle strengths and at the same time has the effect of breakdown of the individual properties of Nilsson states. The extracted l = 1 and 2 (d, p) sum below 2 MeV has about the same magnitude as in 185,187 W. It comprises a rather small fraction of the expected strengths. The observed states below 2 MeV are compared with predictions of the quasiparticle–phonon model. Of particular interest is the identification of “quasi-bands” with inverse spin sequence based on the state 9 / 2 + at 622.8 keV; this indicates some transition aspects from rigid rotors of light W to γ -soft nuclei in the Os-Pt region.