Interpretation of Some of the Excited States of4nSelf-Conjugate Nuclei

An attempt is made to give a general account for some of the excited levels of $4n$-type self-conjugate light nuclei, especially for characteristic low-lying $0^{+}$ levels and also for the $2^{+}$ levels which appear not too far above the $0^{+}$ levels in every case except the ${\mathrm{O}}^{16}$ ground state. It is pointed out that these $2^{+}$ levels may arise from the same configuration as the lower lying $0^{+}$ states which are considered to be deformed. The degree of deformation is estimated from the $0^{+}$—$2^{+}$ energy separation and found to correspond to quite high deformations in some cases. The 6.06-Mev, $0^{+}$, pair emitting state in ${\mathrm{O}}^{16}$, which is considered to be a "hole configuration" by Christy and Fowler, may be deformed and is suspected to have a shape like a line of four alpha particles. Also, a rotation-like series of levels with spins and parities, $0^{+}$, $1^{-}$, $2^{+}$, $3^{-}$, and $4^{+}$ among the highly excited states of ${\mathrm{Mg}}^{24}$ which appears to correspond to a series expected for a linear rotator with six alpha particles in a line is discussed. With ${\mathrm{Ne}}^{20}$, indications of medium-deformed states are found. Analogous discussions on the levels in ${\mathrm{Be}}^8$ and ${\mathrm{C}}^{12}$ are tried although the experimental evidence is less conclusive.