Energy Spectrum and Angular Distributions of Neutrons from the Reaction Be⁹(p, n)B⁹ at 8 to 14 MeV of Proton Energies

The Be ⁹ ( p , n )B ⁹ reaction has been studied by using a fast neutron spectrometer with a hydrogen gas radiator. The energy spectrum of neutrons from the reaction at 14.1 MeV of proton energy was obtained and three new excited levels (3.07, 4.14 and 4.94 MeV) in B ⁹ were observed. They are consistent with the levels of the mirror nucleus, Be ⁹ , and the level scheme of intermediate coupling model introduced by Kurath. Moreover, the angular distributions of the Be ⁹ ( p , n )B ⁹ neutrons at 8.1 to 14.1 MeV of proton energies were obtained. The results do not agree with the theory of Austern, Butler and McManus. The isotropic parts of the neutron angular distributions become larger as the incident proton energies decrease. It is probably due to the fact that, in the lower energy region, the formation of compound nucleus is more preferable.