Cross section fluctuations in alpha particle scattering by 24Mg, 26Mg and 28Si

The aim of the present investigation is to evaluate average properties of highly excited compound nucleus states from an analysis of fluctuations observed in nuclear reaction cross sections as a function of energy. Studied are the elastic and inelastic scattering of alpha particles by24Mg, 26Mg and 28Si at bombarding energies ranging from about 18 to 28 MeV. From the cross section fluctuations it is possible to determine : ( I ) the average to tal level width F of compound nucleus levels as a function of excitation energy; (2) the relative contribution of direct inter action processes , y D , and compound nucleus formation , l - y D , to the cross section; (3) the effective number of reaction channels, Neff. From the value of I one may derive the level density at high excitation energies. Zie: Summary