Angular Distributions of (α, n) Reaction son Be and C

The angular distributions of neutrons from the Be 9 (α, n )C 12 reaction which leaves C 12 in its ground-, 4.43- and 9.6-MeV excited states have been measured for alpha-particle energies between 17.5 and 22.1 MeV. These angular distributions show patterns which may be interpreted in terms of direct interaction theory. The essential feature of the distributions for each neutron group seems not to change with incident energy. The angular distributions of the ground-state neutron group from the C 12 (α, n )O 15 reaction were taken at alpha particle energies from 20.0 to 21.8 MeV. Marked change of distributions with bombarding energies. is not found, while it was seen in the C 12 (α, p )N 15 reaction at the same energy range.