Photodisintegration Processes in Light Even-Even Nuclei yielding Alpha-Particles

The photodisintegration processes splitting the nuclei 12 6 C and 16 8 O completely into alpha-particles have been studied in some detail by the photographic plate method. It is found that, for energies below about 25 MeV resonances occur in the excitation functions, indicating that a compound nucleus interpretation may be valid. These results, and also certain data of Green and Gibson concerning the inelastic scattering of neutrons in carbon, are related to excited states of the nuclei 12 6 C and 8 4 Be as intermediate stages in the various processes. Levels in 12 6 C at 9.6 MeV and 11.3 ± 0.3 MeV occur and these yield first an alpha-particle and 8 4 Be in the ground state, while a third level in 12 6 C near 12 MeV is found to yield 8 4 Be in the broad 3 MeV excited state. Other levels in 8 4 Be at 4.1 MeV and 17 MeV, disintegrating into two alpha-particles, are found as intermediate stages in these reactions.