Date of Award


Degree Type


Degree Name

Doctor of Philosophy (PhD)




D.G. Burke


Proton states of ¹⁵³Eu, ¹⁵⁵Eu, ¹⁵⁵Tb, ¹⁵⁷Tb, ¹⁵⁹Tb, ¹⁶¹Tb, and ¹⁶³Ho have been studied using the (α,t) and (³He,d) reactions. Beams of 24 MeV ³He and 25 MeV alpha particles were produced by the McMaster University model FN tandem Van de Graaff accelerator. The reaction products were analyzed with an Enge split-pole magnetic spectrograph and detected with photographic emulsions. Ratios of the cross sections between the (α,t) and (³He,d) reactions were used as an indication of the ℓ-values for the proton transfers, and the spectroscopic factors were extracted using DWBA calculations. Interpretation of the results is made in terms of the Unified Model.

The results of the present work confirm the assignments of the 3/2⁺[411] and 5/2⁺[413] Nilsson orbitals in the terbium isotopes. The I = II/2 members of the 5/2⁻[532] and 7/2⁻[523] orbitals are identified in ¹⁶¹Tb and ¹⁵⁹Tb and their assignments confirmed in ¹⁵⁷Tb and ¹⁵⁵Tb. It is necessary to invoke appreciable Coriolis mixing between these two orbitals in order to describe the observed rotational level spacings and the spectroscopic strengths. The assignment of the 7/2+[404] orbital is confirmed in ¹⁵⁵Tb and ¹⁵⁷Tb and this orbital is identified in ¹⁵⁹Tb and ¹⁶¹Tb. Previous assignments of the 1/2⁺[411] particle state with vibrational admixtures are confirmed in ¹⁵⁷Tb and ¹⁵⁹Tb and the state is identified in ¹⁶¹Tb. The present results support the earlier evidence for the existence of a second fragment of the 1/2⁺[411] orbital in ¹⁵⁹Tb and suggest the presence of a similar state in ¹⁵⁷Tb. The assignment of the the 5/2⁺[402] orbital is made and tentative assignment of the 1/2⁺[411] orbital is considered for each of the terbium isotopes. In ¹⁶³Ho, the assignments of the 7/2⁻[523] and 7/2⁺[404] orbitals are confirmed, and strong evidence for the assignment of the 3/2⁺[411], 1/2⁺[411], 5/2⁺[402] and 1/2⁻[541] orbitals is found. In the europium isotopes, the assignments of the 5/2⁺[413], 3/2⁺[411] and 5/2⁻[532] orbitals are confirmed, and evidence for the assignment of the 7/2⁻[523], 1/2⁺[411], 7/2⁺[404] and 1/2⁻[541] orbitals is considered.

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