The Reactions Li⁷(p, n)Be⁷, B¹¹(p, n)C¹¹ and Al²⁷(p, n)Si²⁷ at 8 to 14 MeV

The ( p , n ) reactions for lithium, boron and aluminium targets were studied by using two kinds of proton-recoil, fast-neutron spectrometers. One is an addition type originated by Calvert, Jaffe and Maslin, the other is a type with hydrogen gas radiator. The angular distributions of Li ⁷ ( p , n )Be ⁷ neutrons corresponding to the ground and the 0.43 MeV excited states doubles at 8.1 to 14.1 MeV of proton energies and corresponding to the 4.65 MeV excited state of Be ⁷ at 14.1 MeV of proton energy were obtained. Using the activation method, the excitation curve of this reaction was observed with 15 MeV proton beam. The angular distributions of neutrons from the reaction B ¹¹ ( p , n )C ¹¹ (the ground state) at 8.1 to 14.1 MeV and from the reactions Al ²⁷ ( p , n )Si ²⁷ (the ground and the excited states) at 14.1 MeV of proton energy were also observed. The theory of Austern, Butler and McManus does not agree with the obtained results in the case of the reaction B ¹¹ ( p , n )C ¹¹ , but agrees with that in the reaction Al ²⁷ ( p , n )Si ²⁷ . It was observed that, for the reaction B ¹¹ ( p , n )C ¹¹ , the isotropic parts of the angular distributions of neutrons became larger as the incident proton energies decreased and, in the cases of the reactions of Li ⁷ ( p , n )Be ⁷ and B ¹¹ ( p , n )C ¹¹ , the angular distributions of neutrons showed large variations for the different proton energies.