Two-Neutron Excitations in light nuclei via the ((18)O,(16)O) reaction at 84 MeV

A study of light neutron rich nuclei was pursued at the Catania INFN-LNS laboratory by the ((18)O,(16)O) reaction at 84 MeV incident energy on (9)Be, (11)B and (13)C targets. The (16)O ejectiles were detected at forward angles by the MAGNEX magnetic spectrometer. The energy spectra of (15)C show several known low lying states up to about 7 MeV excitation energy as well unknown resonant structures at higher excitation energy. The strong excitation of these latter together with the measured width of about 2 MeV FWHM could indicate the presence of collective modes of excitation connected to the transfer of a correlated neutron pair. Similar features characterize the energy spectra of the (11)Be and (13)B nuclei.