Münster 2017 – wissenschaftliches Programm
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HK: Fachverband Physik der Hadronen und Kerne
HK 60: Structure and Dynamics of Nuclei IX
HK 60.5: Vortrag
Freitag, 31. März 2017, 15:15–15:30, F 2
Pygmy Skin and Core Polarization Modes in Pb isotopes — •Nadia Tsoneva and Horst Lenske — Institut fur Theoretische Physik, Universität Gießen, Heinrich-Buff-Ring 16, D-35392 Gieβen, Germany
We have analysed theoretically recent high resolution measurements of the electromagnetic dipole response of 206Pb below the neutron separation energy which was performed at the HIγ→S facility of Duke University. The obtained experimentally spectral distributions and values for the total electric and magnetic dipole strength are compared to EDF+QPM calculations. The detailed theoretical study of the fragmentation pattern of low-energy electric dipole excitations allows for the first time to separate the pygmy dipole resonance from the tail of the giant dipole resonance and multi-phonon excitations showing striking difference of their decay patterns. Furthermore, based on the experiment and the comparison with EDF+QPM and relativistic RPA theories, the dipole polarizability αD=122.18±9.72 mb/MeV and the neutron skin thickness rskin= 0.151 fm in 206Pb are extracted. The newly obtained experimental and theoretical information is used to predict the Maxwellian-averaged cross section of the 205Pb(n,γ′)206Pb reaction at 30 keV. The astrophysical impact of different counterparts of the electric and magnetic dipole spectra related to the s-process of stellar nucleosynthesis is discussed.