Münster 2002 – wissenschaftliches Programm
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HK: Physik der Hadronen und Kerne
HK 10: Poster Session: Nuclear Physics/Spectroscopy
HK 10.25: Poster
Dienstag, 12. März 2002, 10:30–12:45, Foyer Chemie
Investigation of the 208Pb(γ,γ′) Reaction Near and Above the Neutron Emission Threshold* — •A. Shevchenko, T. Hartmann, Y. Kalmykov, P. von Neumann-Cosel, A. Richter, N. Ryezayeva, S. Volz, J. Wambach, and A. Zilges — Institut für Kernphysik, Technische Universität Darmstadt, Germany
A highly-sensitive study of E1, M1 and E2 excitations in 208Pb at energies close to the neutron threshold is presented. The resonant photon scattering experiment with an endpoint energy of 9 MeV has been performed at the S-DALINAC using two HPGe detectors with 100% efficiency. The experiment extends previous studies [1] to higher excitation energies. A detailed picture of the fine structure of the dipole strength near and above the neutron emission threshold in 208Pb is obtained. The deduced E1 strength distribution is compared to microscopic QPM calculations including the coupling to complex degrees of freedom. The main low-lying E1 strength is concentrated in two regions near 5.5 and 7.3 MeV. The latter one complies with RRPA predictions for the pygmy dipole resonance [2].
[1] J. Enders et al., Phys. Lett. B486 (2000) 15.
[2] D. Vretenar et. al., Phys. Rev. C63 (2001) 047301. * Supported by the DFG under contract FOR 272/2-1.