Unbound excited states in 19,17C

The neutron-rich carbon isotopes C-19,C-17 have been investigated via proton inelastic scattering on a liquid hydrogen target at 70 MeV/nucleon. The invariant mass method in inverse kinematics was employed to reconstruct the energy spectrum, in which fast neutrons and charged fragments were detected in coincidence using a neutron hodoscope and a dipole magnet system. A peak has been observed with an excitation energy of 1.46(10) MeV in C-19, while three peaks with energies of 2.20(3), 3.05(3), and 6.13(9) MeV have been observed in C-17. Deduced cross sections are compared with microscopic DWBA calculations based on p-sd shell model wave functions and modem nucleon-nucleus optical potentials. J(pi) assignments are made for the four observed states as well as the ground states of both nuclei. (C) 2008 Elsevier B.V. All rights reserved.