Veranstaltungskalender

NuSTAR Seminar

• Mittwoch, 08. Februar 2012   11.00 Uhr -- Seminarraum Theorie, Südbau, III. Stock
  Peter von Neumann-Cosel, TU Darmstadt
  "Complete Electric Dipole Strength from Relativistic Proton Scattering and the Neutron Skin in 208Pb"
  

  Scattering of polarized protons with energies of a few 100 MeV at angles close to and including 0° is presented as a new spectroscopic tool for the study of the electric dipole response in nuclei. Complete electric dipole strenth distributions can be extracted between about 5 and 20 MeV with two independent methods based on a multipole decomposition analysis of the cross sections and the combined information from spin transfer observables. A case study of 208Pb demonstrates excellent agreement with other probes but reveals the presence of previously unknown E1 strength just above the neutron threshold. Furthermore, the Coulomb-nuclear interference term in the cross sections shows sensitivity to the underlying structure of E1 transitions, allowing for the first time an experimental extraction of the pygmy dipole resonance (PDR). Possible information on the neutron skin in 208Pb and the symmetry energy in neutron matter from the measured dipole polarizability and PDR properties is discussed.
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