Abstract
Levels in ¹⁵³Tb populated by the decay of 6.3-h ¹⁵³Dy and in the ¹⁵³Eu (α,4ny)¹⁵³Tb reaction have been studied using Ge(Li), Si(Li), and plastic scintillator detectors for y-ray singles, conversion-electron singles, y-y coincidence and β⁺-y coincidence measurements. Negativ-parity states to spin 35/2 and positive-parity states to spin 27/2 were observed. The level structure was found to be inconsistent with a weak coupling interpretation, but consistent with prediction of the rotational model for a weakly deformed system. A similar investigation of high spin states in ¹⁵⁵Ho populated by the ¹⁵⁰Sm(¹⁰B, 5ny) ¹⁵⁵Ho reaction indicate a level structure very similar to the negative-parity states observed in ¹⁵³Tb. Systematic trends in level structure for off-A nuclei with N<90 show a smooth change in deformation with neutron number. Both coupled and decoupled rotational hands of opposite parities occur in many nuclei in this region and may be accounted for with similar values of the deformation and moment of inertia within the same nucleus. The particle-plus-rotor model with Coriolis mixing was used to calculate energies and transition probabilities for states in ¹⁵³Tb. Reasonable agreement with experimental data could be obtained for a deformation β of 0.15. The negative parity states were considered in the context of the rotation-alignment model. Better agreement for the energies of high-spin negative-parity states was achieved by the addition of a term linear in spin to the parameterization of the energies of the unmixed states.
Devous, Michael David (1976). Investigation of the energy levels of 88-neutron, odd-proton nuclei. Texas A&M University. Texas A&M University. Libraries. Available electronically from
https : / /hdl .handle .net /1969 .1 /DISSERTATIONS -508264.