Search for Resonance Phenomena in SILICON-28 + SILICON-28 Reactions.
('28)Si + ('28)Si reactions have been studied in a search for resonance phenomena similar to those observed in reactions involving lighter nuclei, especially lighter alpha-particle nuclei. Charged particle detection of the evaporation residues at a fixed laboratory angle provides weak evidence for the existence of small (2%) structures in the fusion excitation function. Measurements of the characteristic gamma rays of the evaporation residues reveal 4% structures in the ('50)Cr production cross section, consistent with structures of approximately 2% in the total cross section for fusion. The spacing and the magnitude of these structures are shown to be consistent with their arising from successive increments in the value of the maximum angular momentum which leads to fusion. The differential cross section for elastic scattering and for inelastic scattering for Q-values greater than -7 MeV have been measured, at 80(DEGREES) and 90(DEGREES) in the center-of-mass system, for bombarding energies between 70 and 150 MeV. For energies greater than 95 MeV these excitation functions show both broad and narrow structures, similar to the data for lighter identical Boson systems. These data are shown to be consistent with surface transparency in the ('28)Si + ('28)Si interaction, similar to the situation for the lighter systems. The probable origin of these phenomena in molecule formation, or in orbiting and multiple -step processes, is discussed. The work presented in this thesis constitutes the first study of resonance phenomena in the ('28)Si + ('28)Si system, and the first in any system consisting exclusively of nuclei heavier than ('16)O.
- Pub Date:
- December 1980
- Physics: Nuclear