Investigating high-j single-particle energies in Z = 51 nuclei

  • Alan Mitchell

Student thesis: Phd


The work of this thesis consists of a systematic study of low-lying, proton single- particle states in Z = 51 isotopes. States in 113-125Sb were populated via (alpha,t) and (3He,d) single-proton adding reactions, performed on stable even tin isotopes. The Yale tandem accelerator delivered beams of 37.5-MeV alpha particles and 25-MeV 3He nuclei for the reactions. Outgoing tritons and deuterons were momentum analysed using an Enge split-pole spectrometer. To obtain absolute cross sections, the product of target thickness and spectrometer aperture size was calibrated for each target, using sub-Coulomb alpha- particle elastic scattering. States were observed up to ∼4 MeV excitation energy. Angular momentum transfer assignments were made through comparison of angular distributions and ratios of cross sections between different reactions. Relative spectroscopic factors ex- tracted through a DWBA analysis allowed energy centroids of the observed single-particle strength to be reconstructed.These measurements build upon the results of a previous (alpha,t) study, which was per- formed on the same targets. The previous measurements estimated that ∼ 90% of the pieg7/2 and pieh11/2 strength was held in the lowest-lying 7/2+ and 11/2- states, respectively. The difference in energy of these states increased with increasing neutron excess, and al- though they were in agreement with theoretical calculations that included contributions of the tensor interaction, poor statistics limited the information obtained regarding the weak fragments of high-j single-particle strength. Careful examination of these fragments, with the use of greater statistics, has been performed in this work. The (3He,d) measurements aid in making l transfer assignments and provide complementary information regarding the low-j states.Binding energies of the pieg7/2 and pieh11/2 orbitals measured in this work were compared to the energies of the lowest-lying 7/2+ and 11/2- states and theoretical calculations that include the tensor interaction. Though shifted higher in energy due to the fragmentation, trends in the centroids appear to be consistent with the lowest-lying states. The trend of the pieg7/2-pieh11/2 energy difference is in quantitative agreement with the predicted effects of the tensor interaction, with increasing neutron excess.
Date of Award31 Dec 2012
Original languageEnglish
Awarding Institution
  • The University of Manchester
SupervisorSean Freeman (Supervisor)


  • Nuclear physics
  • Single-particle energies

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