CONFIGURATION MIXING OF MAJOR SHELLS IN MASS-1L AND MASS-17 NUCLEI

The odd-parity (T=12) levels of O17 are investigated within the framework of the spherical shell model in order to determine the importance of configuration mixing of the (2s, 1d) and 1p major shells. Particles in the 2s12 and 1d52 subshells and holes in the 1p12 subshell are considered. It is shown that a configuration space which includes both 2-particle-1-hole states and 4-particle-3-hole states is required to achieve good agreement between calculated and experimental energies in the range of excitation from 3.06 to 8.88 MeV. As confirmed by previous work, calculations based on a truncated 2-particle-1-hole space predict excitation energies that are higher by about 2 MeV than the observed values. In addition, the effects of (2s12, 1d52)-1p12 mixing on the odd- and even-parity (T=1) states of N16 above its four lowest levels are evaluated. The consequences of this mixing are a lowering of calculated energies by an average of 2-3 MeV and many changes in the predicted sequence of levels. The significance of these results in relation to the neutron elastic scattering cross section for N15 is discussed, and a need for more experimental data on the spins and parities of N16 levels is indicated. © 1969 The American Physical Society.