Resonance phenomena in the interaction of fast neutrons with beryllium and aluminium

The total scattering cross-sections of beryllium and aluminium have been measured by a transmission method for neutrons of energies between 0∙35 and 0∙55 MeV and 1∙8 and 4∙0 MeV. Resonances have been found in the scattering by beryllium at a neutron energy of 2∙6 MeV and in the scattering by aluminium at neutron energies of 2∙4 and 2∙9 MeV. It has been shown that the cross-section for the reaction 9Be (n, α) 6He also has a resonance at 2∙6 MeV, and an accurate determination of the cross-section for this reaction has been made. A discussion is given of the properties of the energy level in 10Be responsible for the resonances in the case of beryllium.