Low-lying magnetic excitations of doubly-closed-shell nuclei and the nucleon-nucleon effective interaction

The description of low-lying magnetic states of doubly-closed-shell nuclei puts severe constraints on the spin and tensor channels of the effective nucleon-nucleon interaction. A study of the low lying magnetic spectra of 12C, 16O, 40Ca, 48Ca and 208Pb nuclei within the Random Phase Approximation (RPA) theory is presented. An investigation by using four phenomenological effective interactions comparing results for spectra and electron scattering form factors with experimental data is shown. Then self-consistent RPA calculations are presented to test the validity of the finite range D1 Gogny interaction. Particular attention has been paid to observe the sensitivity of the quantities studied to different interactions.