CORE POLARIZATION AND PARTICLE-HOLE EXCITATIONS IN 40CA AND 48CA

Using the Hamada-Johnston interaction, the negative parity particle hole excitations of 40Ca and 48Ca are calculated with and without the inclusion of core polarizations. The lowest 3- states are found to be very sensitive to core polarizations. The random-phase approximation with the bare matrix elements over-estimates the collectivity of these 3- states. The inclusion of the exchange self-screening diagram (Aph) largely reduced the collectivity, and thus improves the agreement with experiment. The calculated energies of the low-lying states of 48Ca are in significantly better agreement with experiment than for 40Ca when the core-deformation components are not included in the wave functions for both nuclei. The experimental relative transition strengths of the 3- and 5- states in 40Ca are satisfactorily reproduced by the calculation. © 1969.