The study of nuclear reactions at intermediate energy

Angular distributions were determined for inelastic proton scattering to ten residual states in Si28. Measurements were carried out at 100 KeV steps in the incident energy range of 12 to 15 MeV. Since the purpose of the experiment was to search for intermediate structure in the inelastic reaction excitation functions, all determinations were made with a beam energy resolution of 100 KeV, The Van de Graaff accelerators of the University of Oxford were used for the experiment. The analysis of the 1000 proton spectra recorded in the course of the experiment was performed entirely by computers. It was found that the angular distributions change rapidly with incident proton energy, and that the reaction excitation functions exhibit structure of the intermediate type. Cross-correlation analysis revealed that there is significant correlation between the structures associated with the different reaction excitation functions. The experimental data were compared with the predictions of the doorway state theory of intermediate structure. It was found that both the characteristics of the intermediate structure in the excitation functions and the existence of correlation between the structures of the different excitation functions are in accord with the predictions of this theory. The experimental results were also considered in relation to the statistical theory of nuclear reactions. It was found that the experimental values of the mean squared deviation of the cross-sections associated with particular inelastic reactions were in reasonable agreement with the values calculated on the basis of this theory. In the experimental situation studied it was found that this theory also offers some explanation for the existence of correlation between the structures associated with the different excitation functions. It was concluded that both the doorway state theory and statistical theory provide possible interpretations of the observed intermediate structure.