The (n,n'gamma) reaction at En = 14.1 MeV has been studied for O16 and Ca40. Differential cross sections were obtained for the scattering by the ground states and several excited states. The excitation of the lowest 3- states was quite strong fpr each nuclide. This is evidence that the collective octupole description is valid for these 3- states. The elastic cross sections were successfully fitted using the optical model. The optical parameters which resulted were employed in DWB calculations to predict scattering cross sections for the lowest 3- states. of O16 and Ca40. For these calculations, the 3- states were represented by collective octupole vibrations. The agreement with experiment was good in the case of Ca40 but poor in the case of O16. The latter result may be due to the inadenquacy of the DWB method for such a light nucleus. Energy, yield and angular distribution measurements were made for the deexcitation gamma rays. For O16 the results were used to deduce excitation cross sections which were in good agreement with the neutron data. It was observed that states higher than the first 3- levels in O16 and Ca40 seldom decay by direct ground state transitions but rather by cascade events which proceed throught the first 3- states. This result is in accord with the assumption of a collective vibrational nature for these states if it is assumed that some of the higher states are formed on top of the 3- level.
| Identifer | oai:union.ndltd.org:uottawa.ca/oai:ruor.uottawa.ca:10393/10582 |
| Date | January 1964 |
| Creators | McDonald, W. John. |
| Publisher | University of Ottawa (Canada) |
| Source Sets | Université d’Ottawa |
| Detected Language | English |
| Type | Thesis |
| Format | 129 p. |
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