STRUCTURE OF SD SHELL NUCLEI .4. 20NE, 21NE, 22NA AND 24MG

The shell model with the phenomenological effective interaction is applied to study level structures of 20Ne, 21Ne, 22Ne, 22Na and 24Mg. The full basis in the sd shell is taken in 20Ne to diagonalize the energy matrices. This example confirms that SU3 symmetry and the super-multiplet provide a very good way of truncation. This truncation is used to calculate level schemes of many nuclei beyond 20Ne. Even though deviations of the effective interaction from the pure Q-Q interaction and the spin-orbit interaction break the SU3 symmetry and the super-multiplet, the main components of calculated wave functions in low-lying energies can be very well labelled by these two symmetries. Generally, good agreement with observations is found. Particularly, the lowest rotational bands are nicely explained. Exceptions are the level structure of 22Na and 1 2+ in 19O and 21Ne, which are too low in the calculation, and the K = 2 bands in 22Ne and 24Mg, which are again too low in the calculation. © 1969.