Proton emission induced by polarized photons

The proton emission induced by polarized photons is studied in the energy range above the giant resonance region and below the pion emission threshold. Results for the 12C, 16O and 40Ca nuclei are presented. The sensitivity of various observables to final state interaction, meson exchange currents and short range correlations is analyzed. We found relevant effects due to the virtual excitation of the $\Delta$ resonance.Comment: 12 pages, 11 figures, 1 tabl

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

We have studied the low lying magnetic spectra of 12C, 16O, 40Ca, 48Ca and 208Pb nuclei within the Random Phase Approximation (RPA) theory, finding that the description of low-lying magnetic states of doubly-closed-shell nuclei imposes severe constraints on the spin and tensor terms of the nucleon-nucleon effective interaction. We have first made an investigation by using four phenomenological effective interactions and we have obtained good agreement with the experimental magnetic spectra, and, to a lesser extent, with the electron scattering responses. Then we have made self-consistent RPA calculations to test the validity of the finite-range D1 Gogny interaction. For all the nuclei under study we have found that this interaction inverts the energies of all the magnetic states forming isospin doublets.Comment: 19 pages, 13 figures, 7 tables, accepted for publication in Phys. Rev.

Effective tensor forces and neutron rich nuclei

We study the effects of the tensor term of the effective nucleon-nucleon interaction on nuclear excited states. Our investigation has been conducted by using a self-consistent Random Phase Approximation approach. We investigate various nuclei in different regions of the isotopes chart. Results for a set of calcium isotopes are shown.Comment: 4 pages, 4 figures, 1 table Proc. 10th International Spring Seminar on Nuclear Physics New Quests in Nuclear Structure, Vietri Sul Mare, May 21-25, 201

Two Proton Emission with Electromagnetic Probes

A model to study two-proton emission from nuclei induced by electromagnetic probes is developed. The process is due to one-body electromagnetic operators, acting together with short-range correlations, and two-body $\Delta$ currents. The model includes all the diagrams containing a single correlation function. The sensitivity of the cross section to the details of the correlation function is studied by using realistic and schematic correlations. Results for the $^{16}$O nucleus are presented.Comment: 9 pages, 8 figures, Contribution to the 6th. Workshop on "Electromagnetic Induced Two-Hadron Emission",Pavia, 200