The dipole strength distribution above the one-neutron separation energy was measured in the unstable 130Sn and the double-magic 132Sn isotopes. The results were deduced from Coulomb dissociation of secondary Sn beams with energies around 500 MeV/nucleon, produced by in-flight fission of a primary 238U beam. In addition to the giant dipole resonance, a resonancelike structure ("pygmy resonance") is observed at a lower excitation energy around 10 MeV exhausting a few percent of the isovector E1 energy-weighted sum rule. The results are discussed in the context of a predicted new dipole mode of excess neutrons oscillating out of phase with the core nucleons.

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The α( 10 Be, α) 10 Be resonant scattering reaction has been measured at nine 10 Be beam energies from 25 to 48 MeV, scanning out resonances in 14 C from excitation energies of 13 to 24 MeV. Angular distribution measurements were used to assign the spin and parity of 5 − to resonances at E x = 18.82(2) and 19.67(2) MeV and 6 + at E x = 20.80(2) MeV. The data also strongly indicate a 3 − resonance at 17.32(2) MeV. The systematic uncertainty on the excitation energies is 175 keV. An R-matrix analysis has been performed for the excitation energy range 16.5 to 22 MeV. The data are discussed in terms of cluster bands in 14 C.

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