| Popis: |
High spin states in 80Sr have been studied using the techniques of in-beam γ-ray spectroscopy. The reaction used was 54Fe(29Si, 2pn)80Sr at beam energies between 85 and 110 MeV. γ-γ coincidence measurements were performed with a thin target to investigate the level structure. Both neutron gated and singles angular distribution measurements were carried out to aid in the assignment of level spins. The directional correlation ratios extracted from the γ-γ coincidence data provided a consistency check for the spin assignments. Level lifetimes were measured by the Doppler shift attenuation method in a thick target γ-γ coincidence measurement. The ground state band has been identified up to (26+) and three previously unobserved sidebands have been discovered. The deduced level scheme is compared with cranking model calculations; the predicted transformation to mostly non-collective excitations of an oblate shape is not observed experimentally. The behaviour of the J(1) and J(2) moments of inertia is discussed and presented as evidence for either static or dynamic γ-deformation in the light Sr isotopes. In addition, the level structure is compared with IBM-2 calculations. These calculations indicate the importance of proton excitations across the Z=40 subshell gap, into the g9/2 orbital, and suggest that the lowest lying 80Sr sideband can be identified with the collective IBM-2 quasi-γ band. NUCLEAR REACTIONS 54Fe(29Si, 2pn), ,em>E = 85 - 110 MeV; measured Eγ, Iγ(θ), γ-γ, n-γ coincidences, DCO ratios, Doppler shifted γ-ray lineshapes. 80Sr deduced levels, J, π, τ. Enriched target, Ge(Li), Ge, NE213 detectors. |
