(α, n) reactions and cascade γ-transitions

Cross section ratios of the ground and isomeric states formation in reactions on 107Ag, 109Ag and 113In are calculated on the basis of an assumption that in a low-energy region the (α, n)-reaction proceeds through a) compound nucleus formation, b) neutron evaporation and c) cascade γ-transitions. The number of cascade γ-quanta and excitation energy distribution between γ-quanta and neutron are not postulated beforehand but are calculated on the basis of a statistic theory. By comparison with an experiment the parameter of spinor dependence of nuclear levels density is found. It is shown that the average number of γ-quanta in the cascade grows approximately linearly with increase of α-particles energy. The γ-quantum energy spectrum in the (α, n)-reaction is calculated. The γ-quantum distribution has maximum in the field of low energies (approximately 1 MeV) which with increase of primary particles energy is shifted slowly to the field of higher energies being simultaneously broadened